PLEA2011 Proceedings Vol1

27th International Conference on Passive and Low Energy Architecture

nniversar a h y t 0 3

ARCHITECTURE & SUSTAINABLE DEVELOPMENT Magali Bodart Arnaud Evrard Editors

> Proceedings vol. 1  UCL PRESSES UNIVERSITAIRES DE LOUVAIN

ORGANISED BY ARCHITECTURE & CLIMAT

PLEA 2011 ARCHITECTURE & SUSTAINABLE DEVELOPMENT Magali Bodart Arnaud Evrard Editors

Volume 1 Conference Proceedings of the 27th International Conference on Passive and Low Energy Architecture Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 ARCHITECTURE & SUSTAINABLE DEVELOPMENT Volume 1 of (2) Conference Proceedings of the 27th International Conference on Passive and Low Energy Architecture Louvain-la-Neuve, Belgium, 13-15 July 2011

© Presses universitaires de Louvain, 2011 Registration of copyright : D/2011/9964/18 ISBN : 978-2-87463-276-1 ISBN download version (pdf) : 978-2-87463-278-5 Printed in Belgium All rights reserved. No part of this publication may be reproduced, adapted or translated, in any form or by any means, in any country, without the prior permission of Presses universitaires de Louvain. Graphic design and layout : Sylvie Rouche. Distribution : www.i6doc.com, on-line university publishers available on order from bookshops or at Diffusion universitaire CIACO (University Distributors) Grand-Rue, 2/14 1348 Louvain-la-Neuve, Belgium Tel: +32 10 47 33 78 Fax: +32 10 45 73 50 [email protected] Distributor in France : Librairie Wallonie-Bruxelles 46 rue Quincampoix 75004 Paris, France Tel: +33 1 42 71 58 03 Fax: +33 1 42 71 58 09 [email protected]

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

TABLE OF CONTENTS (VOLUME 1) FOREWORD..................................................................................................................................................................10 Magali Bodart, Arnaud Evrard PLEA YESTERDAY, TODAY AND TOMORROW...........................................................................................................13 Jeffrey Cook, Simos Yannas

PRACTICE INTERACTION BETWEEN ACTORS Toward Sustainable Architecture....................................................................................................................................21 Kristel De Myttenaere Towards More Sustainable Neighbourhoods: Are Good Practices Reproducible And Extensible? A Review of a Few Existing “Sustainable Neighbourhoods”..........................................................................................27 Anne-Françoise Marique, Sigrid Reiter Tracking Design and Actual Energy Use: CarbonBuzz, an RIBA CIBSE Platform.........................................................33 Judit Kimpian, Sophie Chisholm Identity of Sustainability: from Technique to the Sensory and Experiential....................................................................39 Neveen Hamza Designing For Only Energy: Suboptimisation.................................................................................................................45 Ronald Rovers, Katleen De Flander, Leo Gommans, Wendy Broers.

EDUCATION OF SUSTAINABLE DESIGN Multidisciplinary Master Zero Energy Building - Design Project based on Workshops for Professionals......................53 Wim Zeiler Sustainable Environmental Design Consultancy: Practices Informed And Practical Outcomes....................................59 Michael Smith-Masis, Jorge Rodriguez, Maria Mena-Deferme What Do Young People Tell Us About Sustainable Lifestyles When They Design Sustainable Schools?.....................65 Andrea Wheeler, Dino Boughlagem, Masoud Malekzadeh Academic Advocacy: Teaching Outside The Academy...................................................................................................71 Alison Kwok, Walter Grondzik, Bruce Haglund Is Solar Design a Straitjacket for Architecture?..............................................................................................................77 Tiffany Otis Designing for Sustainability: Pedagogical Challenges and Opportunities .....................................................................83 Andrew Gibson, Sergio Altomonte, Peter Rutherford Teaching Vernacular Architecture and Rehabilitation in Relation to Bioclimatic Design Elements.................................89 Maria Philokyprou Cooperative Design in a Postgraduate Distance Learning Scheme in Brazil : A Case Study on a more Sustainable Low-cost Housing Proposal................................................................................95 M. A. Sattler, L. M. S. Andrade, R. R. M. P. Barros, G. S. Tenorio New Opportunities in Teaching Sustainability in Spain by Competences.....................................................................101 Maria Lopez De Asiain, Pilar Perez Del Real, Jaime Lopez De Asiain A Prototype from the Solar Decathlon Competition Becomes an Educational Building in Sustainable Architecture....107 M. Carolina Hernández-Martinez, César Bedoya, Alfonso Garcia-Santos, Javier Neila, Estefania Caamaño Passive and Low Energy Architecture in Education of Contemporary Architecture.....................................................113 Barbara Widera Dissemination of the Brazilian Code for Building Energy Efficiency Labeling Through a Distance Course in a Virtual Learning Environment................................................................................................................................119 Fernando O. R. Pereira, Alice C. Pereira, Raphaela W. Fonseca, Fernando C. Pires , Luíza C. Castro, Mary A. Yamakawa Actively Teaching Passive Heating & Cooling..............................................................................................................125 Thomas A. Gentry

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. ASSESMENTS OF SUSTAINABILITY Sustainability Indicators in Buildings - Identifying Key Performance Indicators...........................................................133 Lone Feifer Do Current Environmental Assessment Methods Provide a Good Measure of Sustainability? Or what should be a Good Measure for Green Building Standard?.............................................................................139 Edna Shaviv Urban Sustainability Assessment Systems - How Appropriate are Global Sustainability Assesment System?...........145 Dimitra Kyrkou, Melissa Taylor, Sofie Pelsmakers, Roland Karthaus Assessment of Sustainable Buildings - A case for Enabling Post Occupancy Verification...........................................151 Julie Gwilliam What is the Relationship between Design Excellence and Building Performance? With Particular Reference to Education Buildings........................................................................................................157 Yanti Chen, Daniela Besser Jelves, Brian Ford Sustainable Architecture And Sustainable Design Assessment Tools..........................................................................163 Wim Zeiler Analyzing the Application of Energy Efficiency Labelling to Hotel Buildings................................................................169 Myrthes Marcele Farias Dos Santos, Luciana Hamada, Ricardo Wargas De Faria

CLIMATIC, WATER AND BIODIVERSITY CONTEXT A Pattern Langage Design Tool for Water Efficient Gardens - A Knowledge Based Computer-Aided Design (KBCAD) tool for Water Efficient Landscape Design....................................................................................................177 Daphna Drori, Edna Shaviv Urban River Microclimates...........................................................................................................................................183 Abigail Athway, Steve Sharples Design Alterations in Urban Self-built Houses in Campinas, Brazil: Analysis of their Effects on Ventilation Through CFD...................................................................................................189 Mariela Oliveira, Lucila Labaki, Paulo Vatavuk Microclimate in Urban Forest Fragments.....................................................................................................................195 Christiane Dacanal, Lucila Chebel Labaki Local Adaptation Processes to Climate Variability, Towards Living with Floods in the Padma River Bank Areas: The Case of Bangladesh..............................................................................................................................................201 Amreen Shajahan, Yousuf Reja Towards Resilient Urban Ecosystems..........................................................................................................................207 Hugo Soriano Sustainable Urban Planning of High Density Cities by Urban Climatic Mapping An Experience from Kaohsiung, Taiwan.......................................................................................................................213 Chao Ren, Ka Lun Lau, Kam Po Yiu, Edward Ng Urban Climatic Map and STEVE Tool for Sustainable Urban Planning in Singapore...................................................219 Steve Kardinal Jusuf, Nyuk Hien Wong, Chun Liang Tan City Planning With Urban Wind in Complex Coastal Cities – An Experience of Hong Kong .......................................227 Edward Ng, Xipo An Suburban Neighbourhood Adaptation for a Changing Climate Developing Climate Change Scenarios for Suburbs....................................................................................................233 Rajat Gupta, Matthew Gregg Urban Morphology And Temperature Mapping Comparative Study - Case Study: Singapore’s Commercial Aera......239 Nyuk Hien Wong, Steve Kardinal Jusuf, Rosita Samsudin, Marcel Ignatius Trees And Heat Fluxes: How Much do they Contribute to the Energy Balance at Urban Spaces?.............................245 Loyde Vieira de Abreu, Lucila Chebel Labaki Forecasting Carbon Emissions of the UAE Residential SectorA Case Study of Abu Dhabi........................................251 Hassan Radhi, Steve Sharples Environmental Design of a Building - Climatic Context................................................................................................257 Charline Weissenstein, Jean-Claude Bignon

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. Interdisciplinary Methodological Approach for Urban Water Management in Densely Urbanized Areas Within Brussels - Geology, History and Architectural Engineering...............................................................................263 Valérie Mahaut, Kevin De Bondt, Chloé Deligne Field Survey on Water-saving Efficiency of Roof Rainwater Harvesting System in Taiwan ........................................269 Ruey-Lung Hwang, Han-Hsi Liang, Ruei-Ling Chen, Shiu-Ya Shue Analysis of Seasonal Differences in Microclimate Formed in a Local Small City of Paddy Field Areas A New Approach using Airborne Remote Sensing and CFD Simulation......................................................................273 Takashi Asawa, Akira Hoyano, Tamon Yoshida, Masahito Takata Rethinking the Green Roof - A proposal of Grey Water Phytodepuration System.......................................................279 Alberto Gómez González, Inmaculada Morgado Baca, Mariana Chanampa, César Bedoya Frutos, Consuelo Acha Román, Javier Neila González. Measuring the Effects of Urban Form on Urban Microclimate......................................................................................285 Matthias Irger

PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES) Improving Areas Around Railway Stations to Promote Changes in the Mode of Transportation..................................293 Yves Hanin, Véronique Clette, Amélie Daems, Thomas Dawance, Martin Grandjean, Véronique Rousseaux Creating a Sustainable Transport System - a Study of the Comprehensive Mobility Plan, Issues thereof and Policies Adopted in Pune Urban Region in India...................................................................................................297 Jayashree Deshpande Urban Mobility at the City of Joinville, Brazil, Focusing on Bicycle Integration with Public Transportation..................301 Ana Mirthes Hackenberg, Marcio Lisboa, George Henrique Rangel Costa, Edson Murakami, Fernando Humel Lafratta The Significance of Gauging Stakeholder Interests in Energy Saving and Environmental Management n Green Hospitals.........................................................................................................................................................307 Phanchalath Suriyothin, Wannee Wattanapailin The Code of Sustainable Homes As a Viable Driver Towards a Zero Carbon Future in UK........................................313 Heba Elsharkawy, Peter Rutherford, Robin Wilson A Model for Transdisciplinary Design in Passive Illumination.......................................................................................319 Sascha Bohnenberger, Leanne Zilka, Jordi Beneyto-Ferre, David E. Mainwaring

MATERIAL (ENVIRONMENTAL AND HEALTH ASPECTS) / WASTE MANAGEMENT Straw Bale Construction; a Solution for Low Cost Energy Efficient Rural Housing in the Earthquake Affected Regions of Central Southern Chile?...............................................................................................................327 Christopher J. Whitman, Daniela Fernández Holloway An Environmental Assessment of Insulation Materials and Techniques for Exterior Period Timber-frame Walls........333 Hans Valkhoff The Thermal Behaviour of Cross-Laminated Timber Construction and its Resilience to Summertime Overheating...339 Owen Jowett PCM Analysis as a Strategy in Passive Thermal Conditioning in Floors......................................................................345 Isabel Cerón, M. Carolina Hernández-Martinez, Carmen Montejo, Javier Neila New high-performance insulation materials:Aerogels. Case study: new Munch Museum in Oslo...............................351 Maria Meizoso, Jose Carlos Gonzales Application of Cool Materials on Solar Protection Devices to Reduce Energy Consumption and Improve Thermal Comfort Conditions in Residential Buildings....................................................................................357 Michele Zinzi, Emiliano Carnielo, Stefano Agnoli The Future Life Cycle of Intelligent Facades................................................................................................................363 Craig Lee Martin, Craig Stott Hemp Lime Bio-composite in Construction - A study into the Performance and Application of Hemp Lime Bio-composite as a Construction Material in Ireland.............................................................................369 Patrick Daly Impact of Building’s Wall Lifespan on Greenhouse Gas Index According to the Technical Solutions Chosen.............375 Marc Méquignon, Luc Adolphe, Frederic Bonneaud

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. Waste Management - Various aspects in city of Pune, India.......................................................................................381 Arti Patil The Application of “Techno-mud” In Residential Buildings In Chile - A Critical Review................................................387 Mirentxu Ulloa, Benson Lau

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE) The Representative Day Technique in the Analysis of Thermal Comfort in Outdoor Urban Spaces............................397 Roberta Cocci Grifoni, Giovanni Latini, Simone Tascini An optimized model for a thermally comfortable Dutch urban square..........................................................................403 Sanda Lenzholzer Exploring Outdoor Climates and Urban Design in a Historic Square in Dublin............................................................409 Ágota Szücs, Gerald Mills Thermal Comfort in Urban Public Spaces: Case Studies in Pedestrian Streets in Cities of Sao Paulo State, Brazil...............................................................................................................................415 Maria Solange Gurgel de Castro Fontes, Cristiane Dacanal, Carolina Lotuffo Bueno-Bartholomei, Marialena Nikolopoulou, Lucila Chebel Labaki Elaboration of a Methodological Guide of Sound Ambiences to Evaluate Urban Soundscapes: the ASTUCE Research Project....................................................................................................................................421 Catherine Semidor, Henry Torgue, Jacques Beaumont, Aline Barlet, Julien Delas, Cécile Regnault, Flora Gbedji Adaptive Outdoor Comfort Model Calibrations for a Semitropical Region...................................................................427 Mate Thitisawat, Kasama Polakit, Jean-Martin Caldieron, Giancarlo Mangone Proposal of an Outdoor Thermal Comfort Index: Empirical Verification in the Subtropical Climate.............................433 Leonardo Marques Monteiro, Marcia Peinado Alucci Evaluation of Comfort Conditions and Sustainable Design of Urban Open Spaces in Crete.......................................439 Marianna Tsitoura, Michailidou Marina, Theocharis Tsoutsos Urban Heat Island Study on Building Morphology related with Micro-climate Condition and Energy Consumption within Singapore Commercial Area.....................................................................................445 Nyuk Hien Wong, Steve Kardinal Jusuf, Marcel Ignatius The Influence of Occupation Modes on Building Heating Loads: the Case of a Detached House Located in a Suburban Area.......................................................................................................................................................451 Tatiana De Meester, Anne-Françoise Marique, Sigrid Reiter A Review of Thermal Comfort Criteria for Naturally Ventilated Buildings in Hot-Humid Climate with Reference to the Adaptive Model..........................................................................................................................457 Doris Hooi Chyee Toe, Tetsu Kubota Comfort Temperatures And Comfort Range In Low Cost Dwellings In Arid Climate....................................................463 Luis Carlos Herrera, Gabriel Gómez-Azpeitia, Pavel Ruiz, Adolfo Gomez Occupant Behaviour and Energy Performance in Dwellings: A Case Study in the Netherlands..................................469 Merve Bedir, Evert Hasselaar, Laure Itard Occupant Interaction with the Interior Environment in Greek Dwellings During Summer............................................475 Aikaterini Drakou, Aris Tsangrassoulis, Astrid Roetzel Exploiting Adaptation and Transitions - Learning from Environments beyond the Boundaries of Confort...................481 Natalia Kafassis Financial Motivation to Improve Thermal Comfort and Reduce Carbon in Office Buildings.........................................487 Joshua Kates The Summer Performance of the BASF House...........................................................................................................493 Lucelia Rodrigues, Mark Gillot Green School: Environmental Performance and Perception - A Post Occupancy Evaluation of Two Singapore Schools............................................................................................................................................499 Nurul Ain Saadon, Beng-Kiang Tan Importance of Occupant’s Adaptive Behaviour for Sustainable Thermal Comfort in Apartments in India....................505 Madhavi Indraganti The Climate/Comfort Comparison And The Basis Of Sustainable Design Impact of Climate Change and Technological Development........................................................................................511 Luca Finocchiaro, Mark Murphy, Tore Wigenstad, Anne Grete Hestnes

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. Delivering Quality Indoor Environment in Houses - The Potentials and Impact of Building Materials for Facade Design in Cairo...........................................................................................................................................517 Wael Sheta, Steve Sharples Developing Sustainable School Design in Iran - A thermal comfort survey of a secondary school in Tehran..............523 Sahar Zahiri, Steve Sharples, Hasim Altan A Case Study into the Relation Between Temperature and Work Productivity in Offices in the UK.............................529 Laura Jones, Pieter De Wilde Fading Shades of Green Perceptions and Responses to Working in a Sustainable Office.........................................535 Ida G. Monfared, Steve Sharples Definition of Occupant Behaviour Patterns with Respect to Ventilation: An Approach to the Summer Thermal Comfort of Apartments from the Real Estate Market in Santiago de Chile....................................................541 Felipe Encinas Pino Thermal Comfort Temperature in Outdoors for Extreme Warm Dry Climate................................................................547 Gonzalo Bojórquez-Morales, Gabriel Gómez-Azpeitia, Rafael García-Cueto, Pavel Ruiz-Torres, Aníbal Luna-León Thermal Comfort in Hospital Environments..................................................................................................................553 Léa Y. Dobbert, Demóstenes F. Silva Filho, Cristiane Dacanal, Cleide A.M. Silva Performance of Outdoor Thermal Comfort and Indoor Heat Flux of Rooftop Lawn Greening in the Subtropical Climate............................................................................................................................................559 Kuo-Tsang Huang, Chuang-Hung Lin, Han-Hsi Liang Redefining Pavilions: Improving Upon Outdoor Comfort Conditions A Performance Study of London Pavilions...........................................565 Ellen Cameron, Milena Stojkovic, Konstantina Saranti, Olga Conto Thermal Strategies for Economical Dwellings in Warm Dry Climates in Mexico..........................................................571 Irene Marincic, José Manuel Ochoa, Maria Guadalupe Alpuche Subjective Thermal Comfort in Urban Spaces in the Warm-humid City of Guayaquil, Ecuador..................................577 Erik Johansson, Moohammed Wasim Yahia Comparison of the EN 15251 and Ashrae Standard 55 Adaptive Thermal Comfort Models in the Context of a Mediterranean Climate.................................................................................................................................................583 Astrid Roetzel, Aris Tsangrassoulis, Aikaterini Drakou, Gustavo De Siqueira The Influence of Environment on People’s Thermal Comfort in Outdoor Urban Spaces in Hot Dry Climates The example of Damascus, Syria................................................................................................................................589 Moohammed WasimYahia, Erik Johansson Statistical Model Evaluation and Calibrations for Outdoor Comfort Assessment in South Florida...............................595 Jean-Martin Caldieron, Mate Thitisawat Kasama Polakit, Giancarlo Mangone Adaptive Principles for Thermal Comfort in Dwellings From Comfort Temperatures to Avoiding Discomfort...............601 Noortje Alders, Stanley Kurvers, Eric Van Den Ham

HVAC, EQUIPMENT AND REGULATION (COMPLEMENTARY TO DESIGN) Investigation of Space-heating Strategies in Very Low-energy Houses Using Dynamic Simulations Case of Decentralized Wood Stoves Approaches.................................................................................................................609 Laurent Georges, Catherine Massart Hybrid Ventilation as an Energy Efficient Solution for Low Energy Residential Buildings............................................615 Peter Foldbjerg, Thorbjørn Færing Asmussen, Karsten Duer Design Strategies for Community-Scale Renewable Energy Solutions.......................................................................621 Lisa D. Iulo, Rohan R. Haksar, Seth Blumsack Technologies and Sustainable Policies for Decreasing Energy Consumption in Buildings in Greece.........................627 N. Papamanolis, M. Mandalaki Building Regional Intelligence......................................................................................................................................631 Christopher Domin, Larry Medlin, Brent D. Vander Werf Development of the Solar Cooling in the Mediterranean Area.....................................................................................639 Francesco Patania, Antonio Gagliano, Francesco Nocera, Aldo Galesi Methodological development of seasonal cooling energy needs by introducing ground-cooling systems...................645 Marta Oliveira Panão, Helder Gonçalves

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. Building Integrated Micro- generation Systems for Cooling, Heating, and Dehumidification in hot and Humid Climate Zones..............................................................................................................................................................651 Thomas Spiegelhalter Approach to Classification and Evaluation of Naturally Cooled Buildings....................................................................659 Gianluca Cadoni Passive & Hybrid Cooling for Production Single-Family Housing................................................................................665 Thomas A. Gentry

BUILDING PHYSICS (HYGROTHERMIC AND ACOUSTIC) The Influence of Thermal Properties of The Envelope Components on the Thermal Performance of Naturally-ventilated Houses.....................................................................................................................................673 Enedir Ghisi, Ana Gabriela S.A. Cardoso Effect of two Exterior Louver Systems on Solar Transmittance and Indoor Thermal Conditions: Experiment and Simulations...................................................................................................................................................................679 Abel Tablada De La Torre, Dirk Saelens, Staf Roels Hygrothermal Performance of Vegetation on Cladding and Translucent Façade Systems..........................................685 Javier Alonso, Francesca Olivieri, Javier Neila, César Bedoya Housing Beyond The Technical, a Social Realisation - a Comparative Examination of Energy Efficient Housing.......691 Phillipa Marsh Turn the Gas off Zero-energy Achievement Based on Free Floating Internal Conditions Between Health-related Limits......................697 Geoffrey van Moeseke Thermal Performance Evaluation of Four Low Cost Houses in Santa Maria - Brazil...................................................703 Giane Grigoletti, Renata Rotta, Sâmila Muller Performance of Shading Device in Classrooms of Zero Energy Building in Singapore...............................................709 Nyuk Hien Wong, Erna Tan Solar Chimney System of Zero Energy Building in Singapore - Ventilation Performances in Classroom....................715 Nyuk Hien Wong, Alex Yong Kwang Tan Delayed Gratification: Interseasonal Heat Storage, as a Carbon-Neutral Refurbishment Strategy for 19th Century Dwellings...........................................................................................................................................721 Greg Keeffe Residential Buildings with Green Walls - Advantages, Disadvantages and Symbols Evoked by the Use of Ficus pumila and Parthenocissus tricuspidata Species...........................................................................................727 Mariene Valesan, Beatriz Fedrizzi, Miguel Aloysio Sattler Energy Efficiency of a Pre-vegetated Modular Facade Prototype................................................................................733 Maria Isabel Touceda, Francesca Olivieri, Javier Neila Passive Strategies for Roofing Design in Costa Rica - Shading, Form and Materiality...............................................739 Michael Smith-Masis The Application of Passive Downdraught Evaporative Cooling in Hot and Dry Climate of China................................745 Huang Xuan, Brian Ford Evaluation of Passive Cooling in Low Energy Police Office.........................................................................................751 Hilde Breesch, Bram De Meester, Ralf Klein, Alexis Versele Sustainability And Heritage Conservation Assessment of Environmental Performance and Thermal Comfort Conditions Of Historic Churches.........................757 Magdalini Makrodimitri, James W. P. Campbell

BUILDING PHYSICS (DAYLIGHTING) Daylight Performance Assessment and Design Strategies in the Adjoining Spaces of Atrium Buildings.....................765 Jiangtao Du, Steve Sharples Daylight and Solar Control in Building: A New Angle Selective See-thorough PV-façade for Solar Control................771 Francesco Frontini A Method for Integrating Visual Comfort Criteria in Daylighting Design of School.......................................................777 Beatriz Piderit, Magali Bodart, Tomas Norambuena

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. A Novel Louver System for Increasing Daylight Usage in Buildings............................................................................783 Kevin Thuot, Marilyne Andersen The Evaluation of Solar Energy Potential and Energy needs for Heating and Lighting Using LIDAR Data Applications on two Real Built Up-Areas......................................................................................................................789 Virginia Gori, Carla Balocco, Claudio Carneiro, Gilles Desthieux, Eugenio Morello An Interactive Performance-Based Expert System for Daylighting Design..................................................................795 Jaime M. L. Gagne, Marilyne Andersen, Leslie K. Norford A Comprehensive Method to Determine Performance Metrics for Complex Fenestration Systems............................801 Shreya Dave, Marilyne Andersen Balancing the Energy Savings and Daylighting Performance of External Perforated Solar Screens Evaluation of Screen Opening Proportions..................................................................................................................807 Ahmed Sherif, Hanan Sabry, Abbas El-Zafarany, Rasha Arafa, Tarek Rakha, Mohamed Anees The Performance Evaluation of an Advanced Daylighting System in Multi-story Office Buildings: Measurement and Simulation.......................................................................................................................................813 Jianxin Hu, Jiangtao Du, Wayne Place Investigation of 3D Projection for Qualitative Evaluation of Daylit Spaces...................................................................819 Coralie Cauwerts, Magali Bodart The Potential Daylight Penetration in Deep Plan Offices.............................................................................................825 Viktoria Lytra Decision Making in Selecting the best Matching Hybrid Lighting System....................................................................831 Mohammed Mayhoub, David Carter Comparative Analysis of Admitted Luminous Flux and Daylight Spatial Distribution in Openings with Solar Control Devices.........................................................................................................................................................................837 Amilcar J. Bogo, Fernando O. R. Pereira, Anderson Claro The Light Comfort Zone of Micro-landscape Plant community– from the Viewpoint of Occupancy Environment........843 Chuang-Hung Lin, Chien-Yuan Han, Ruey Lung Hwang The Visual Environment in t he Vernacular Dwellings at Mount Pelion, Greece..........................................................849 Natalia Sakarellou-Tousi, Benson Lau The Poetics of Contemplative Light in the Church of Notre-Dame-du-Haut designed by Le Corbusier.......................855 Dimitris Kaimakliotis, Benson Lau The Poetics of Civic Light in Le Corbusier’s Assembly Building at Chandigarh...........................................................861 Saurabh Barde, Benson Lau Architectural Light in Contemporary Religious Buildings..............................................................................................867 Isha Anand The User Intervention on the Environmental Delight of the BASF Research House at University of Nottingham.......873 Dineshkumar Sekar, Benson Lau, Jyothsna Durga Giridhar Design Tools for Architects: The Meaning of Solar and Daylight Access Information in Design..................................879 Isaac Guedi Capeluto Daylight Evaluation of Retrofitting Methods: Conversion of the ‘Spierer’ Tobacco Warehouse in Volos, Greece........885 Polytimi Ilia Effectiveness of Dynamic Daylighting - Post Occupancy Evaluation of a Higher Ed Building.....................................891 Judy Theodorson, Julia Day Solar Control Mechanisms: Effects on Daylight & Thermal Performance An Experimental Study on a Public Library..................................................................................................................897 Karl Borg, Vincent Buhagiar Strategies for Improving Thermal Performance and Visual Comfort in Office Buildings of Central Chile....................903 Waldo Bustamante G., Felipe Encinas, Alan Pino, Roberto Otarola AUTHOR INDEX..........................................................................................................................................................909

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

FOREWORD The 27th PLEA conference PLEA2011 - Architecture and Sustainable Development marks the 30th anniversary of PLEA. The topics of the conference tackle a broad range well beyond the subject of energy : • • • • • • • • • • • •

Examples of sustainable architecture and urban design Briefing and programmatic requirements of mixed-use multi-purpose buildings Urban Renewal and Refurbishment Education in sustainable design Comfort (indoors / outdoors) Design tools and methods Building Science (hygrothermal, daylighting, acoustics) Materials (environmental impact and health aspects) Complementary HVAC equipment and controls Waste management Rainwater collection and biodiversity Mobility (within and between cities)

Following from the last PLEA conference that was held in Quebec in 2009, we want this celebratory PLEA 2011 in Louvain-la-Neuve to provide a special meeting ground for architects, engineers and researchers to debate the theme of sustainable architecture and the different aspects of sustainable development that range from the scale of the city to those of materials and components. To animate these discourses our PLEA members were invited to nominate what they felt to be the most important issues for discussion and debate. Three main themes were selected by the PLEA 2011 Organizing Committee out of those put forward and a number of experts were invited to address each of these themes. The invited experts will present their views in the course of three forums that will be held over the three days of the conference to launch debates we would like to see as open and rich. The three themes to be addressed are  : • • •

the collaboration between architects, engineers and researchers- the fusion of art and technique, from theory to practice; education for sustainable architecture; do current environmental assessments methods provide a good measure of sustainability ?

Each of these topics will be also addressed by papers presented in the conference technical sessions to be held prior to those forums. This book of Proceedings presents the latest thinking and research in the rapidly evolving world of architecture and sustainable development through 255 papers which were selected out of more than 750 abstracts that were proposed by authors coming from over 60 countries. All papers were read and commented on by the members of the technical committee whose critical comments and recommendations enabled the selection of 125 oral presentations and some 130 poster presentations (supported by short oral presentations) that will be held at the conference. In each technical session the order of oral presentations has been chosen so as to begin with a relatively general exposition, finishing the session either with a conclusion or with a provocative paper addressing the session topics in an original way. Both oral and poster papers are included in this book of proceedings. The PLEA 2011 Proceedings are also available on a USB key provided to all participants of the conference and on the PLEA website www.arct.cam.ac.uk/PLEA/home.aspx

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. Acknowledgements We wish to thank the members of the International Technical Committee of PLEA2011 listed below for their participation in the selection and critical review of the 750 abstracts and 340 papers submitted for this conference. Their contribution has ensured the quality of the final papers. We would like to thank them especially for complying with the very tight schedules imposed by the Organizing Committee. Dr. Rajendra Adhikari Politecnico di Milano, Italy Dr. Sergio Altomonte University of Nottingham, UK Prof. Servando Alvarez University of Sevilla, Spain Prof. Marilyne Andersen Swiss Federal Institute of Technology (EPFL), Switzerland Arch. Shady Attia Université catholique de Louvain, Belgium Dr. Magali Bodart Université catholique de Louvain, Belgium Dr. Frédéric Bonneaud University of Toulouse, France Dr. Vincent Buhagiar University of Malta, Malta Prof. Waldo Bustamante Catholic University of Chile, Santiago, Chile Prof. Paula Cadima Architectural Association Graduate School, London, UK Prof. André De Herde Université catholique de Louvain, Belgium Prof. Kristel de Myttenaere Université Libre de Bruxelles, Brussels, Belgium Arch. Arnaud Deneyer Belgium Building Research Institut, Belgium Prof. Denise Duarte University of São Paulo, Brasil Dr. Emmanuel Dufrasnes School of Architecture of Strasbourg, Strasbourg, France Arch. Felipe Encinas Université catholique de Louvain, Belgium Dr. Arnaud Evrard Université catholique de Louvain, Belgium Prof. E. de Oliveira Fernandes University of Porto, Portugal Prof. Brian Ford University of Nottingham, United Kingdom Prof. Joana Goncalves Universidade de Sao Paulo, Brazil Architectural Association Graduate School, London, UK Dr. Elisabeth Gratia Université catholique de Louvain, Belgium Prof. Dean Hawkes University of Cambridge, UK Prof. Arnold Janssens Ghent University, Belgium Prof. Ken-ichi Kimura International Research Institute on Human Environment, Japan Dr. Louis Laret SECO, Brussels, Belgium Dr. Maria Lopez de Asiain Seminario de Arquitectura y Medio Ambiente, Sevilla, Spain Dr. Jaime Lopez de Asiain Seminario de Arquitectura y Medio Ambiente, Spain Dr. Valérie Mahaut Université de Montréal, Canada Prof. Isaac A. Meir University of the Negev, Israël Dr. Nicolas Morel Swiss Federal Institute of Technology (EPFL), Switzerland Prof. Edward Ng The Chinese University of Hong Kong, Shatin, NT, Hong Kong Prof. Fernando O. R. University of Santa Catarina, Bresil Arch. Dana K. Raydan RMJM Ltd Prof. Juan Reiser Pontificia Universidad Católica del Perú, Perú Prof. Sigrid Reiter University of Liege (ULg), Liège, Belgium Prof. Emmanuel Rey Ecole polytechnique fédérale de Lausanne, Switzerland Arch. Hans Rosenlund CEC Design, Olofström, Sweden Prof. Miguel Sattler Federal University of Rio Grande do Sul, Bresil Dr. Rosa Schiano-Phan Architectural Association Graduate School, London, UK Prof. Gianni Scudo Politecnico di Milano, Milano, Italy Prof. Catherine Semidor ENSAP Bordeaux, France Prof. Roels Staf Katholieke Universiteit Leuven, Belgium Arch. Sophie Trachte Université catholique de Louvain, Belgium Ir. Geoffrey Van Moeseke Université catholique de Louvain, Belgium Mr. Willi Weber Energétique du bâtiment, Chêne-Bougeries, Switzerland Prof. Simos Yannas Architectural Association Graduate School, London, UK 11

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. We would also like to thank the authors of all the submitted and accepted papers who have shared with us their experience and research results and who are the most important contributors to this conference. Last but not least, we wish to thank all those who have helped with the organization of this event. Although we have made, under the supervision of the International Technical Committee, every effort to ensure that the work presented here is correct and absent of factual errors, the contents and opinions expressed in the papers are the sole responsibility of the authors. Magali Bodart, Arnaud Evrard Co-chairs of PLEA2011

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

PLEA

Yesterday, Today and Tomorrow The Origins of PLEA : 1980 - 1987 PLEA, Passive and Low Energy Architecture—a unique network organisation—was conceived, nurtured, and propelled almost single-handedly by Arthur Bowen (1926-1987), when he was Professor of Architecture at the University of Miami, Coral Gables, Florida, USA. At the beginning of the 1980’s he understood a particular and timely need for sharing professional and technical knowledge on a global basis, especially in the face of an emerging stylistic irresponsibility in American architecture called « post-modernism ».   As a practising architect, Bowen was appalled by both the performance and aesthetic direction of recent building design, whether in the United States or the United Arab Republics. He regarded the potential of bioclimatic architecture as an untapped root that could renew and redirect the field. Well established building science knowledge, as well as the collaborative interests of consulting engineers and research scientists were being ignored, together with the lessons of nature and of indigenous architecture. To him, this was a mission of social responsibility that had a revolutionary sense of urgency. Since no existing organisation was prepared to deal with the administrative, political, and financial intricacies of such a bold program, to say nothing of the philosophical commitment, he responded by single-handedly leading the charge. The emergence of PLEA and the sequence of successful international PLEA conferences grew out of the synergetic series of two Expert Group Meetings commissioned by the US Department of Energy and organized by Bowen to initiate the federal passive cooling program in the USA in 1980. The first Group Meeting of fifteen invited foreign experts and three Americans had heavy double assignments of regional monographs plus specialist topic papers. A similar assignment for the second meeting of fifteen American experts also held in Miami, Florida added to this substantial body of existing knowledge to be shared. Unfortunately, the proceedings of these impressive interchanges were never published. In contrast, the subsequent International Passive Cooling Conference of 1981 in Miami Beach, chaired by Arthur Bowen and sponsored by the American Solar Energy Society and the US Department of Energy, resulted in a definitive Proceedings : Passive Cooling. This first and only International Passive Cooling Conference proved the desirability of global exchanges on such fundamental concepts. But especially because of the international aspect, the idea was not attractive to its U.S. sponsors. Thus, the inception of a new international amalgam, first called Passive and Low Energy Alternatives, met off American soil at Bermuda in September 1982. Thereafter, the PLEA monogram referred to Architecture, not alternatives. PLEA was no longer an alternative choice! Succeeding conferences capitalized on the Miami information bases and synthesized international networking by continuing the pattern of commissioned technical position papers and regional monographs. Within this backbone, refereed papers provided the meat of PLEA meetings. PLEA Proceedings were regularly published through Pergamon or the national host organisation. Although sponsorship and financial support came through complex networking, delicate diplomacy, contributions from friends and from unexpected sources, these early PLEA conferences were partly financed out of Arthur’s own pocket, as they were driven by his heart. PLEA welded together fresh alliances, professional as well as personal, across many nations. Each conference was held in a fresh location and season that would inspire and inform bioclimatic researchers. Local culture, cuisine, and building traditions would be featured. International input and participation was encouraged in many ways, starting with paid travel for key researchers. In addition, each PLEA conference would recognize some figure of international leadership by a conference award to

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. identify the critical contributions to the emerging new field of Passive and Low Energy Architecture. A list of PLEA locations and awards illustrates the richness of this evolutionary program : 1982, Bermuda – E. Maxwell Fry and Jane B. Drew; 1983, Crete – John I. Yellott; 1984, Mexico City – Harold Hay; 1985, Venice – James Marstan Fitch; 1986, Pécs, Hungary – Aladar and Victor Olgyay. There was no international PLEA Conference in 1987 because of Arthur’s death in July. In retrospect, the first PLEA conference held on an idyllic island in the middle of the Atlantic was like a surprise party - well known international names were associated with faces and personalities. There was the mutual discovery of global kindred spirits. At Crete in 1983, PLEA became introspective with enthusiastic discussions, not just about eco-techniques but also about self-organization and prospects for continuity. At Mexico City in 1984 these prospects were confirmed with over 1 000 participants. Support by SEDUE and INFONAVIT assured a substantial attendance and venue. With both English and Spanish in simultaneous translation and several volumes of Proceedings published in both languages, the theme of « Eco-techniques Applied to Housing » was discussed long into the nights, and the impact lasted many years. Venice in December 1985 was dark and moody. But the PLEA meetings with a small group of specialists on « Regionalism » were held in a brilliant palace, Ca’ Loredan. Because of the proximity to Hungary, a delegation of their political and technical leaders drove to Venice to confirm the arrangements that the next PLEA meeting would be held behind the Iron Curtain. PLEA ’86 with the theme of « Passive and Low Energy Architecture in Housing » was held at Pécs. It attracted a diverse participation from many countries, as well as leading architects of Hungary.

Reshaping PLEA 1987-1995 The master plan for meetings established at PLEA Pécs proposed that beginning in 1988 there would be two PLEA conferences held each year, one in each hemisphere, and each with a more regional focus. Thus, PLEA 88 held in July in Porto, Portugal with its focus on Mediterranean climates, had already been initiated before Bowen’s death. The Porto theme was « Energy and Buildings for Temperate Climates » and PLEA founder Arthur Bowen (1926-1987) was honored posthumously. At Porto, the challenging issue of the continuity of PLEA without Bowen was first addressed. The PLEA idea was slowly reshaped by a self-initiated Working Group of participant leaders and synthesized into a broad-based organization to continue its already well established record and idealism. By accident, the Working Group also represented a broad geographic and professional spectrum. In addition to Eduardo de Oliveira Fernandes, the chairman of the Portugal 1988 conference, the Working Group included Sergio Los and Natacha Pulitzer of Italy, Janos Szasz of Hungary, Simos Yannas of the UK, Ken-ichi Kimura of Japan, and Jeffrey Cook of the USA. Thus educators and scientists, architects and engineers were brought together globally. At the PLEA 1989 conference at Nara, Japan, Steve Szokolay of Australia was honored, thus embracing two other continents. The theme « Global Environment and Architecture of the Post-Industrial Age » anticipated the global issues of the 1990’s that emerged at Rio and at Kyoto. Already an agreed PLEA charter was published. At PLEA 90 Halifax, Canada, the theme was « Bioclimatic Design in Architecture and Planning ». As at Nara, it was also held adjacent to a national or international solar energy conference. Donald Watson of the USA was honored and the tradition of a private Experts Roundtable was continued. Thereafter, PLEA would have annual meetings of substantial size and independent of the meetings of other organizations. In 1990 the book Regionalismo dell’ Architettura was published in Italy under the editorship of Sergio Los. Guest chapters were based on major papers presented at the PLEA conference focusing on 14

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. regionalism held at Venice in December 1985 since those Proceedings were not published. In 1991, the book Passive and Low Energy Architecture was published in Tokyo as Process Architecture 98. With editors Yuichiro Kodama, Simos Yannas, and Jeffrey Cook, its 160 colored pages in both Japanese and English illustrated works built globally in all climates. PLEA 91, held at Seville, Spain, anticipated the 1992 Seville World Expo in its theme of «Architecture and Urban Space», where appropriately Baruch Givoni was honored. Finally, here the Working Group agreed an arrangement of rotating Directors who would serve for staggered six-year terms, including three officers. Thus, a self-continuing, non-membership organisation was established based on participation in events and subscription to the PLEA Charter, open to all. A PLEA conference held in Auckland, New Zealand in September 1992 has slipped from some memories because the Proceedings were not published. The theme « Architectural Responses to Climate Change » was already a response to the United Nations Rio conference and the emergence of Agenda 21. Under contract from the Commission of the European Communities for Energy, PLEA, in association with the Academy of Athens, produced the Symposium on « Solar Energy and Buildings », 8-10 December 1993 in Athens. Invited papers were presented to a live audience in front of video cameras. The Proceedings as a series of professional videotapes were distributed throughout the European Community. The 1994 PLEA « Architecture of the Extremes » held at the Dead Sea, Israel in July, lived up to its promise of extremes. Harry Tabor, the solar physicist, was honored with the PLEA award. The Dead Sea also was the seedbed for TIA, Teaching in Architecture, a sister organization related to PLEA ideals. The first international TIA conference was held in September 1995, and the second in October 1997, both at Universita’ Degli Studi di Firenze, Italy. The move to a venue in an under-industrialized region was a three-day event in New Delhi, India, in April 1995. Supported by the British Council and hosted by the Centre for Advanced Studies in Architecture of the School of Planning and Architecture, the design workshop was in « Climatically Responsive Energy Efficient Architecture  ». Immediate publications included a Database of the Indian Context Volume, as well as the invited papers in a Design Handbook. These materials were synthesized and reissued as an impressive reference text, Climatic Responsible Architecture, a Design Handbook, 410 pages plus a disc of Temperature Radiation Data was published by Tata McGraw Hill in 2001.

PLEA and Sustainability 1996-2002 In the latter part of the 1990’s, PLEA activities surged in industrialized countries based in part on the growing understanding of how buildings and human environments are critical to global climate and resources. The growing politically acknowledgment of integrated design as a key to sustainability reinforced the PLEA Charter. At Louvain-La-Neuve in Belgium in July 1996, national and European Community sponsorship was reflected in the theme of « Building and Urban Renewal ». Honored by the PLEA Award were the Italian team of Sergio Los and Natacha Pulitzer. In January of 1997 at Kushiro, Hokaido, the northern-most city of Japan, the PLEA theme was « Sustainable Communities and Architecture--Bioclimatic Design in Cold Climates ». A two-day ocean voyage from Tokyo through winter seas intended especially for students included a full day workshop with lectures and bioclimatic exercises. The substantial support of OM Solar (www.omsolar.com), a well commercialized heating system born out of the diverse climates of Japan, included participation by several hundred of their national organization. A model OM Solar house at Kushiro, and handsome publications, including a three volume Proceedings, extended the PLEA agenda. Architect and researcher Ken-ichi Kimura was honored for his extensive contributions internationally. 15

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. The PLEA goal of « Environmentally Friendly Cities » was the theme in June 1998 at Lisbon, Portugal. Benefiting from co-sponsorship with Lisboa Expo ’98, PLEA participants had special access to new energy efficient apartment models, as well as the Expo itself. The World Fair was a first-hand demonstration of the efficient refurbishment and redevelopment of a 350 hectare heavily polluted and degraded industrial site. Continuing the tradition of the PLEA award to a distinguished scientist or practicing architect for their contributions, both were honored : Architect Alexandros Tombazis of Athens, and Dr. J. Douglas Balcomb of the Los Alamos Scientific Laboratory and the National Renewable Energy Center of the USA. PLEA 99 was conceived as a continuing Australian event starting at Melbourne, with a stop at Sydney to look at the new green Olympic facilities and then to Brisbane and to Cairnes, locations separated by 10 degrees of latitude. But the main feature was the technical conference at Brisbane where « Sustaining the Future » was the theme for a truly international meeting. Brenda and Robert Vale of New Zealand were honored. The capstone conference for the old century was PLEA 2000 at Cambridge, UK, in July where Dean Hawkes was honored. It was followed in a week by the third TIA, Teaching in Architecture, conference at Oxford where Baruch Givoni was recognized. The TIA theme of « Sustainable Buildings for the 21st Century: teaching issues, tools and methodologies for sustainability » was again supported by the European Commission. At Cambridge, in illustrious King’s College, the 17th PLEA meeting addressed « Sustainable Design in Architecture, City, and the Environment at the Turn of the Millennium » in one of the most progressive historic towns of Europe. With the 18th PLEA Conference in November 2001 in Florianópolis, Brazil, the new century began on the fifth continent for PLEA. Convened at a nature friendly resort overlooking the Atlantic, the focus appropriately was on Renewable Energy for a Sustainable Development of the Built Environment. Honored was Roberto Oscar Albistar Rivero of Montevideo, Uruguay, whose book «Architecture and Climate» is used by most of the schools of architecture in South America. Toulouse, France is host for the 19th PLEA Conference in July 2002 when « Design with the Environment » is again examined «as a mandatory condition for urban and architectural quality ». Through its global network, the PLEA idea has been spread through conferences, workshops, expert group meetings, competitions, and consultancies, as well as Proceedings and other publications. Especially noteworthy is the series of PLEA Notes: six monograph texts on technical subjects developed through the University of Queensland, Australia (PLEA Notes). The most complete PLEA Archive is in the Special Collections of the College of Architecture and Environmental Design, Arizona State University in Tempe, Arizona, USA. In the preface to the two-volume proceedings of PLEA ’99, the conference chairman, retired PLEA President Steve S Szokolay, wrote, « It has no formal structure or membership. It lives by the dedication of individuals. Its main activity is the organization of annual conferences. Con-ference, in the literal sense; bringing together (con-ferre) of the knowledge, the thoughts and findings of those in the area ». Jeffrey Cook, Regents’ Professor Arizona State University, School of Architecture Tempe, Arizona, 85287-1605 USA

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Update by Simos Yannas PLEA 2003, the 20th PLEA Conference, was devoted to the memory of Jeffrey Cook. Held in Santiago, Chile in November 2003, it took on the topic of Rethinking Development - Are we producing a people oriented habitat ? and recognised the work of architect Glenda Kapstein Lomboy. Returning to Europe, PLEA 2004, the 21st PLEA Conference on Built Environments and Environmental Buildings was hosted at the academic surroundings of the Technical University of Eindhoven, The Netherlands, in September 2004. The work of architects Jon & Riet Kristinsson-Reitsema was recognised with the PLEA Award. PLEA 2005, the 22nd PLEA Conference held in Beirut, Lebanon, in November 2005 took on the theme of Environmental Sustainability - the challenges of awareness in developing societies. Jacques Liger-Belair was honoured with the PLEA Award. The feeling of optimism conveyed by brief glimpses of the city’s reconstruction will stay in memory despite the unimaginable destruction that was to follow. PLEA 2006, the 23rd PLEA Conference, called for Clever Design, Affordable Comfort - a challenge for low energy architecture and urban planning. Held in September 2006 in Geneva, Switzerland, its two volumes of Proceedings comprise some 350 papers totalling over 2000 pages. The architectural office of Metron AG received the PLEA Award. In a first of a new series of PLEA Round Tables, the conference panel and audience linked successfully by video conference with representatives of the American Institute of Architects in the US for a debate on converting theory into practice. PLEA 2007 Sun, Wind and Architecture, the 24th PLEA Conference was hosted by the National University of Singapore 22-24 November 2007. It offered an exhibition on zero energy buildings and coincided with the Singapore 1:1 Island exhibition, a unique opportunity to view the evolution of architecture and urban design trends on the island over the last forty years. There was discussion of the environmental cost of international conferences. PLEA would make the proceedings of conferences available online and delegates would be able to present by video conferencing. Prof. Tay Kheng Soon was the recipient of the PLEA Award in recognition of his pioneering efforts in promoting good design and sustainable architecture in Singapore. PLEA 2008, the 25th PLEA Conference Towards Zero Energy Buildings was organised by the University College Dublin’s Energy Research Group and was held at UCD’s O’Reilly Hall, 22-24 October 2008. It was attended by some 400 participants from 47 countries providing lively discussion and debate in the course of the conference proceedings which encompassed some 150 oral presentations and 110 posters. PLEA 2009, the 26th PLEA Conference Architecture, Energy and the Occupant’s Perspective was held in Quebec City, Canada 22-24 June 2009 and organised by the Groupe de Recherche en Ambiances Physiques (GRAP) at the Universitė Laval. A Manifesto was drafted during the conference and signed by all the participants at the closing session. It is a call for the rehumanisation of architecture through the provision of adaptive opportunities for its inhabitants. G.Z. Brown was the recipient of the PLEA Award for his longstanding contribution to teaching and research. PLEA Kids a special workshop for youngsters was a welcome and memorable initiative. PLEA celebrates its 30th anniversary in Louvain-la-Neuve Belgium, 12-15 July 2011. Simos Yannas

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Toward Sustainable Architecture. Kristel De Myttenaere. BATir, Université Libre de Bruxelles, Bruxelles, Belgium. ABSTRACT: Before being a question of the right choice of material or system, sustainable architecture is a question of attitude in the design process. The philosophy behind the concept of Sustainable Development can help us to define this question of attitude. This paper proposes to go back to the core principles of a Sustainable Development and to analyze them in order to confront them with contemporary architectural practice. This methodology leads to the 3 questions a design process should address in order to qualify the resulting architecture by the adjective sustainable. 

How architecture can conciliate the human being with its natural environment (Sun – Water – Soil – Air) on a quantitative level as well as on qualitative and symbolic one?



How architecture can articulate the different scales of the human being, respecting its individual scale as well as its collective one?

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How architecture participates to transmit to the future generation the structures it has inherited from the past while living in its present time?

Keywords: Architecture, Sustainable Architecture, Sustainable Development, Design Principles, Inhabitant.

1. INTRODUCTION

2. THE TOOLS

Assessing sustainability pushes ourselves to question contemporary architectural practice and can help us to refocus our design abilities behind ethical principles. But in order to achieve that goal, it is about assessing a design that makes sense at the local scale as well as suits criteria’s dictated by the global one. And more than that, if we want to qualify architecture by the adjective sustainable, it is important that we assess also the architectural qualities of the design.

If certain tools help us architects to contextualise our projects by analysing its interactions with its 1 environment and sometimes simulate it, they are generally to focus on one dimension and only to guaranty the optimal result at the large picture. Another generation of tools, more recently developed by our national scientific and technical construction centres, propose to focus on the large scale and list a number of criteria’s a project has to fulfil in order to be qualified by the organisation. These tools tend to fail to integrate specific dimensions related to the context or to architectural qualities. Being developed in a specific context, it is important to understand what they can and what they fail to assess in order to understand their limits. Being general by definition, these tools have to be used in parallel to more specific ones in order to guaranty that global and local stakes are integrated in the design process.

The whole concept of sustainable development can guide us to understand what our practice is putting at stakes and to establish design principles to comprehend the global and the local scale without forgetting to integrate the architectural dimension. This paper proposes to go back to the core principles of a sustainable development in order to understand how its ethical principles can enlighten our contemporary practice. More than a “to do” list, we owe our designers some inspiration. This paper aim at proposing design principles that could help us architect to qualify our architecture by the adjective sustainable. These principles do not pretend to be the only ones possible to define this approach. They just state certain issues that are relevant in terms sustainable architecture but that could be rephrased in another way. We hope this paper could help other architects to deepen their understanding of this approach to propose their own vision of it, as relevant and exhaustive as possible.

But even when a project fulfil all these criteria and has been developed using all the tools available to propose the most appropriate solution to the specific context of the project, there is no guaranty that it could be named and qualified as sustainable architecture. Analyzing what has been developed until now, we can conclude that tools do not address direct questions of architectural design and tend to limit the field of expertise to techniques and materials when they could extend it to the different scales of the spatial dimension as well as of the urban one. This paper proposes to explore the concept of Sustainable Development in order to extract principles that could enlighten a design process. What is at stakes with the concept of sustainable

PRACTICE - INTERACTION BETWEEN ACTORS

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

development is more than just a question of engineers; it is also a question of architects and architectural engineers. As the past thought us that the best architecture has been designed when real questions on society, on the economy, on art, on materials or systems, etc. were addressed to architects, we believe that the concept of sustainable development offers a lot of important and serious stakes that can inspire our design practice. The following graph (figure 1) proposes to analyse these different tools and to place them consider what they aim for. We can see that the core of the triangle is the definition of principles as proposed in this paper. We would like to remind the reader that this is our vision of the problematic. We only propose an analyse of the different tools available to help us qualify and name our design by sustainable architecture hoping this could help other architects to define their own approach. We see the different tools and lists of criteria as methods to help us bring in our design considerations related to global stakes of a sustainable development as well as local stakes of the context in which our design is interacting. The cognitive, analytical and empirical tools belong to this second category when the different lists of criteria’s, whether quantitative, qualitative or contextual, belong to the first one. On top of these, different architect have proposed to interpretate the notion of sustainable architecture through more esthetical, technical or functional dimensions. This can be analysed through the Vitruvius principles to define architecture: beauty, technique and function. If so, the different dimensions as approached by architects are complementary although sometimes paradoxical. Sustainable architecture has to be defined at the crossing of these dimensions in order to be named architecture. But in order to be qualified as well by the adjective sustainable, it has to integrate in its design the different tools available to contextualise its design and the different lists of criteria’s in order to the global stakes of a sustainable approach. We can then set a first conclusion. Sustainable architecture is not just a question if using the right set of tools or list of criteria’s. These can help the designer to deepen his approach and precise his design, but if the project is not sustained by certain design principles, there will be no guaranty that the right direction and the right development will follow. What is proposed in this paper is to define a methodology that could help us to understand how the concept of sustainable development can influence architectural practice and how to define principles that could help us to sustain our design by integrating local and global stakes at the same time.

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Figure 1: The Tools. 3. THE METHODOLOGY In order to see how this concept of sustainable development can influence architectural practice, we 2 have studied it through the different official texts , 3 researches on the topic and at the light of different authors such as Augustin Berque or Edgar Morin to put it into perspective. We have come to the conclusion that the five principles as proposed by the Plan Federal Office of 4 Belgium can summarize the all concept in its generality, its complexity and its specificities. We then have proposed to put this analyse into the perspective of architectural design to see if, and if so, how the concept of sustainable design can influence it. The five principles as proposed by the PFO are the following:  The principle of integration: integrating the economical, social, political and environmental dimension;  The principle of inter and intra generational equity;  The principle of precaution;  The principle of responsibility;  The principle of participation. The first principle is telling us that by integrating the economical, social, political and environmental dimension together, we can optimise the solution proposed. This implies a drastic change of mind. Instead of separating these disciplines and consider that they do not interact with the other dimensions, we analyse the solution considering their interactions with their context. Instead of looking to maximise only one dimension, we are looking for an optimum for all the dimensions together, considering the local and global scale at the same time. The theory of complexity, as studied and developed by the French philosopher 5 Edgar Morin , can help us to fully comprehend this principle, its implications and the difference between looking for the maximal or the optimal. His field of expertise reflects grandly on us architects as we have to work on a daily base with knowledge and specialists from a large field of disciplines, from more technical aspects to psychological and sociological perspectives. His theory of complexity can help us to

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

deal with the collateral contradictions of such an approach. He is proposing that every stake should be analysed in order to identify its level of interactions with the other parameters of the project. Through a scaling system, his method proposes to solve the contradictions by optimizing the benefit of an action at the global scale without neglecting the local one. If we take a simple example to illustrate the method: We all know that speed bumps help to slow down the speed and thus the number of people run over by cars. But at the same time, the slowing down and increasing the speed right after increases the fuel consumption responsible for the increase of CO2 emissions in the atmosphere. When the concentration of CO2 in the atmosphere reaches a certain level, people suffering breathing problem for all sort of reason might experience severe problems leading in certain cases to death. If we can evaluate how much this cause of death would increase by increasing the fuel consumption for a security measure, and how many people it could save in comparison, then and then only, we can take the right decision. The second principle of inter and intra generational equity is putting into perspective the 6 notion of individuality. Augustin Berque proposes to understand the scales of our humanity as being inseparable. This leads us to be an individual with its own needs at the same time as we are part of a family, part of a neighbourhood, part a society and part of a civilisation, and each scale with its own needs. This question reflects a lot for us architects as through architecture we propose a certain hierarchy of organisation and relations between these different scales. If we work for a client, we are at the same time responsible for “other” people. Certain orientations in the design will lead to different modes of relations between the inhabitants, inside and outside the borders of the project. The concept of sustainable development proposes us to design buildings that will naturally lead to behaviours in favour of better equity, within and throughout the different generations. The third principle is the principle of precaution. This principle sets goals way higher than the one of prevention. We can prevent that something bad happen but more than that we can make sure to take all precautions needed in order to protect as well from the non predictable. This could seem impossible without the lightening of Morin’s theories. Again, the scaling system can shed some clarity into this impossibility. Morin states that in every analysis there is a certain amount of more or less unpredictable mistakes. He proposes that these mistakes are the collateral damages of the way the project has interacted over the time with its context. But he also suggests that there is a certain degree of correlation between the amount and consequences of the mistakes and their timeframe of influence. This principle is certainly one of the most important one when we apply it to our practice. It helps us to understand how our milieu is constantly influencing our human being as much, if not more, than we 7 human try to influence our milieu . But more than that,

it proposes that the bigger the scale of influence is, whether we talking about time or space, the more we should use the principle of precaution and only act on what we can guaranty as beneficial in the specific context. Let’s hope this will teach certain individuals we have in our profession who justify their actions on their only intuitions or personal if not egocentric desires. But before all, it helps to understand that everything in a building has different life time expectancy before having to be restored, replaced or destroyed. Steward brand proposes to analyse buildings and their evolution throughout time. What 8 we can conclude from the lecture of his book is that if certain aspects in a building could, so thus, should last long, other should be chosen and integrated in the construction considering its shorter time spent. The fourth principle is the one of responsibility. Through the first and the second principle, we accept our responsibility towards the earth as well as towards humanity. This principle makes us responsible as professional, respons-able. In other words, as architect, we are respons-able to address issues within the local scale in regards to the global 9 stakes . The fifth principle is the one of participation. If we go back to the first and second principles, we understood that nature and culture should not be dissociated, that the natural environment has an influence on the human being at least as important as the human can influence its natural environment. The principle of participation should then not been seen as only the participation of people inside the project but also the one outside the project and the participation of the milieu in which it takes places. This is where the architect can have an influential role by designing solutions that will integrate the vision of the local population as well of his understanding of the milieu in which he is interacting. This methodology helped us to deepen our understanding of the concept of sustainable development and to understand what it puts at stakes in contemporary architecture. We can already conclude that sustainable architecture is not just a question of using the right set of tools or list of criteria in the design process. The ethic behind the concept of sustainable development implies a change in our practice that can be summarized under these five topics:  Architecture should be a media to help reducing the gap between what we consider natural environment as we see the suburb and artificial or cultural environment as we see our towns10. If we manage to propose a connection to our natural environment in an urban context, we can hope to decrease to influence of the population exodus to the suburbs. But more than that, we can hope that this connection will participate to people’s awareness to the ecological cause. Combined with techniques improving the performance of the buildings, at the technical scale as well as the spatial and urban one, we can hope for a

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better architecture in the future with a lower ecological footprint for the people living in them.  Architecture should be a media to improve the relations between the different inhabitants of the project. By inhabitants, we consider the people living in the building as well as neighbours, citizens, visitors or simply people.  Architecture should integrate in its process the fact that all its components will not have the same life time spent. Sustainable architecture can thus not be defined by the utopia of lasting neither by the one of versatility. Sustainable architecture should propose solutions that can be easily adapted in the more or less near future considering the foreseen life expectancy of either the technique or the function.  Architects should face their respons-abilities towards the earth as well as towards the human being.  Architects should consider the milieu in which their design will take place. The milieu should be seen in regards of the theories of Augustin Berque and should be understood as the interactions the environment, both natural and cultural, have with the human being. A sustainable architecture makes the milieu participate to the contextualisation of the project while integrating the stakes at the global scale.

4. THE RESULTS Analysing the concept of sustainable development in order to underline what is at stakes in our contemporary architectural practice helped us to propose our vision on what could be one definition of sustainable architecture. Sustainable architecture can then be defined at the crossing of three main questions every design should address in one way or another. These questions are the following:  How architecture proposes to conciliate the human being with its natural environment?  How architecture proposes to articulate the different scales of our humanity?  How architecture proposes to transmit to the future generations what they have inherited from the past ones? These questions will not guaranty that the design proposed can be qualified as sustainable at the same time as named as architecture. But if these questions are not addressed, we can suspect that some dimensions will not be considered at their proper degree of importance and relevance and that the resulting design will have difficulties to be named and qualified as sustainable architecture. What is proposed in this paper, as the result of the research, is one way to look at the complex question

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of sustainable architecture. We do not have the pretention to believe it is the only way to look at it. We just hope that this methodology proposed can help other architects to define their own approach to it. What we can ensure is that this approach has helped us in our profession as architect as well as of professor and researcher to integrate the sustainable dimension. The first question is addressed to limit the global ecological footprint of our buildings. It states that our environment has as much influence on us human being as we human can influence our environment. In order to reduce the environmental footprint, we should consider all consumptions related to the building performance as well as the collateral consumption related to the usage of the building. It is then the global context of the project that is evaluated in regards of its ecological footprint. It implies all questions related to the right choice of materials or systems as to the right choice of spatial design solutions. The objective is to reduce as much as possible the ecological footprint of our buildings, taking into consideration the consumptions and pollutions related to the performances of the building as well as the collateral consumption related to the location of the building, its integration into a mix urban context, and finally, the consumptions related to the behaviour of its inhabitants. The design should apprehend quantitative dimensions as well as qualitative and symbolic ones. If the energy performances of our buildings have increased over the past years, the energy consumptions figures have not exactly shown to follow that trend. There is a strong need today to invent solutions to reduce the consumptions and pollutions associated to living in a building at the same time as participate to the awareness of its inhabitants to the ecological cause thus influencing the global consumption of that building. If we do not start to integrate the qualitative and symbolic approach, we might never fight what is so called the rebound effect. The second question is addressing the social dimension. This second question is related to the first one. It is stated that if we want to reduce our global ecological footprint, we should stop building our suburbs but start renovating our towns. And if we want to develop our towns, we should consider how we want people to live together and what kind of relations will they be able to maintain in that context. The objective is to reconsider the conditions that are necessary in order to provide comfortable dwellings for people to feel free to develop themselves. In order to do so, we should respect people’s multi 11 dimensionality . We all are individuals at the same as part of a family, of a neighbourhood, of a city, etc. We should provide some spaces where one can feel his own individuality and other where one can feel part of a group, of something bigger. This way, if people feel comfortable to live in more dense areas, we can hope to reduce our general ecological footprint and have a real effect on all sectors of consumption. But more than that, we should strike for that the renovationreconstruction process integrates the principle of

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

conciliation. It means that it should improve the interactions between the inhabitant and its environment. At the same time, the renovationreconstruction process should prioritize areas that can provide all services of centres’ in terms of public transports and commerce accessibility but also a possible connection to the environment, both natural and cultural. The third question is addressing the inheritance dimension. It states that if we start taking into consideration the ecological footprint of our buildings sites, there is a lot of waste and energy consumed that could be saved if we dispose more wisely of what we have at our disposal. It does not mean we should not strike for adapting our structures to our actual needs nor for improving the performance of our buildings. This question states that we should be able to design spaces based to a certain extend on what 12 we already have . We should adapt our program and considerations in order to find a compromising solution that will include both aspects. But we should do this work at the same as considering what is going to happen next when the future generations will inherit our spaces. We should thus work so to make it is possible for the future generations to understand the spaces we have ourselves inherited and so that is possible for them to also appropriate the spaces we are passing and this should be done at the smallest environmental and economical costs. The objective is here to analyse every action we intend on our buildings and spaces in order not only to minimize their negative aspects but to optimize their positive ones. We should thus integrate the principle of precaution to analyse the different components of the buildings and adapt their choices and their combinations considering their lifetime spent and the impact of their exchangeability.

territory to an optimum level in regards to the ecological footprint, we have to consider what will provide a comfortable place for people to live. It is then important to look not just at the performance of the building but before all the comfort it will provide. We have to change focus from building to people since they are the one responsible for the final consumption of the building within its level of performance. It is also important to look at all the transition scales between the private sphere and the public one. We have to look at how we can improve the relation between the inhabitants and their environment, both natural and cultural. And if we want to improve the density of our territories, we should start with the already denser areas to see how we can improve their density in order to optimize their ecological footprint. It is then crucial to limit the renovation-development process to the minimum so to limit the waste and the consumption of materials. But in order to answer to this third question in a sustainable way, we should also integrate the first question and see how the renovation-development process can improve the inter-actions between the inhabitants and their environment. The second question should also be addressed and it should help improving the relations between the different inhabitants of the project, inside its borders as well as outside.

5. CONCLUSIONS We can conclude that the question of sustainable architecture is not just of a question of using the right set of tools or list of criteria. This paper shows that if using these tools and lists can help developing a design in a more sustainable direction, they will not be enough to guaranty that the solution proposed will be named and qualified as sustainable architecture. We cannot pretend to propose a methodology that will guaranty the sustainability of architecture, but we can propose to identify questions that every design should address appropriately if it claims to sustainability of architecture. As acknowledged earlier in the paper, we do not pretend the methodology here proposed will talk to everyone but we hope it will at least help some architecture to identify their own questions, related to their own practice and its own context, when it comes to sustainable architecture. The questions are the following:

Figure 2: Axes of Sustainable Architecture. As shown on the graph (figure 2), these three questions are interrelated. If we want to reduce our general ecological footprint, we should not only look at the performances of the building, we have to consider as well in which context it is located and how much impact the renovation-construction process will generate. If we want to improve the density of our

 How architecture proposes to conciliate the human being with his natural environment? After having analysed the principle of sustainable development, we came to the conclusion than architecture is a good media to help improving the interactions between the human environment and the natural one. In order to do so, the interactions have to work on a quantitative level as well as a qualitative and symbolic one. Augustin Berque helped us to understand that the human being has as much influence on his environment, both natural and cultural, as our environment has influence on us. And although the performances of our buildings have increase over the past years, it does not show in the statistics. If we

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want to fight this rebound effect, we architects have to design buildings that will improve the interactions between the inhabitants and their environment. If we want to reduce our ecological footprint and propose measures that will have an impact on all sectors of consumption, architectural design should integrate quantitative measures as well as qualitative and symbolic ones. Sustainable architecture is then an architecture that proposes to improve the interactions between the inhabitants and their environment, both natural and cultural.

density of our towns in order to reach an optimal level, environmentally, economically and socially, we have to work on improving the relations between the different people living in and outside the project in itself as we have to work on improving the interactions between the inhabitants and their environment, both natural and cultural. Considering the different structures and infrastructures we already have as a stock of materials and energy, working with our patrimony, whether older or newer, should be on of our priority.

 How architecture proposes to articulate the different scales of our humanity? After having analysed the concept of sustainable development, we came to the conclusion that architecture is a good media to improve the connections between people and their good relations. In order to do so, we should as architects work at every scale of our design to question the transition scales between the different spaces of the project, from the public one to the private one. Edgar Morin helped us to understand that we, as human being, belong also to different scales of humanity: we belong to a family, a neighbourhood, a city, a civilisation. Every scale of this humanity has its own needs that we as architects have to integrate and deal with its paradox. If the architect is responsible towards his clients, his before all responsible towards his indirect clients, society. But if we want to reduce the ecological footprint of our dwellings and fight the des-urbanisation that is costing us on an environmental level as well as on a social and economical one, we have to improve the interactions the inhabitants can have with their environment as well as the neighbourhood relations that our spaces will influence. Sustainable architecture is then an architecture that is respons-able towards his clients inside and outside the borders of the project and proposes interesting modes of connections between these different inhabitants.

We can thus conclude on the proposition that sustainable architecture can be defined by core ethic principles. These principles can guide our design by helping us to question in our project the kind of interactions between the inhabitants and their environment is proposed, the kind of connections between the people inside and outside the project is involved and the kind of relation to the patrimony we have inherited and we are transmitting to the future generations is implied.

 How architecture proposes to transmit to the future generations what they have inherited from the past ones? After having analysed the principle of sustainable development, we came to the conclusion that architecture is a good media to integrate different temporalities together. In order to do so, we should as architects analyse the needs of our present time and confront them to the structures and spaces of the past in order to integrate their constraints as well as their benefits in the design proposed. This should be done considering the ecological footprint every action is having. But this should not be done without considering how the future generations will inherit what we are transmitting them and how they will be able at their turn to adapt them to their own needs at minimal environmental and economical costs. This implies a certain ethic in the design process. Sustainable architecture is then an architecture that integrates the needs of the present in the structures and the spaces of the past without compromising the future generations to adapt them to their own needs. These tree questions are inter-related. If we want to reduce our global ecological footprint and improve the

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6. ACKNOWLEDGEMENTS This paper proposes the main conclusion of a research that has been conducted for the Wallonia Region within the international research framework of the task 28 of the International Energy Agency on Sustainable Solar Housing.

7. REFERENCES [1] Architect's Council of Europe, Green Vitruvius: Principles and Practice of Sustainable Architectural Design, James & James, 1999. [2] Brundtland Gro Harlem, Our Common Future: the World Commission on Environment and Development, Oxford University Press, 1987. [3] Zaccaï Edwin, Le développement durable: Dynamique et constitution d'un projet,P.I.E. Peter Lang, 2002. [4] http://www.plan.be/ [5] Edgar Morin, Seven Complex Lessons in education for the future, UNESCO PUBLISHING, 1999. [6] Augustin Berque, Etre humain sur Terre, Gallimard, 1996. [7] Augustin Berque, Ecoumène, introduction à l’étude des milieux humains, Belin, 1999. [8] Stewart Brand, How buildings learn, what happens after they’re built, Penguin, October 1995. [9] Conseil Européen des Architectes, L’architecture, médiatrice des tensions urbaines, Extraits du colloque européen, Unesco, Paris, 1999. [10] Younès Chris et al., Ville contre-nature, La découverte, 1999. [11] Benasayag Miguel, Le mythe de l'individu, La Découverte, 1998. [12] Choay Françoise, L’allégorie du Patrimoine, Le seuil, 1992.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Towards more sustainable neighbourhoods: are good practices reproducible and extensible? A review of a few existing “sustainable neighbourhoods” Anne-Françoise MARIQUE1, Sigrid REITER1 1

Local Environment: Management & Analysis (LEMA), University of Liège, Liège, Belgium

ABSTRACT: Several urban neighbourhoods built or retrofitted from the 1990s have become renowned for their sustainability and are often presented as good practices, as far as sustainable development and low energy architecture are concerned. Although these “sustainable neighbourhoods” receive a great deal of media coverage, they seem to stay “single” experiments and are rarely repeated in other territories or at larger scales. This paper first discusses the European context, which fostered the development of these pilot experiments. It then proposes a rereading of eight famous sustainable neighbourhoods in an analytic way that is more than descriptive to highlight good practices to repeat and weaknesses to avoid and question the reproducibility of these experiments. The settings grid, which describes the achievement conditions and some common characteristics of these urban projects, highlighted through this analysis, is compared with a Belgian dwelling project, and this comparison allows us to explain why it can be difficult to extend these concepts more widely. Finally, the paper proposes several guidelines to promote energy efficiency and sustainability at the urban scale in order to support the planning of more sustainable urban projects. Keywords: sustainable neighbourhoods, urban sustainability, best practices

1. INTRODUCTION The world is undergoing the largest wave of urban growth in history. In 2008, for the first time, more than half of the world’s population (that is to say 3.3 billion people) lived in urban areas. By 2030, this number will swell to nearly 5 billion [1]. As cities and towns are now known to be responsible for the majority of greenhouse gas emissions [2] and energy consumption, it becomes urgent to reduce their environmental impact and to identify how to improve existing and new urban neighbourhoods and how to make them more sustainable. These causes for concern were expressed for the first time in 1987 in the famous Bruntland report [3], which introduced the concept of sustainable development. From then on, the need for more sustainable urban forms has been treated in several successive European texts and charters that recognise the role of European cities and towns in pursuing sustainability [4] and the importance of cooperation and local actions in achieving a more sustainable future [5, 6]. In this European framework, budgets were granted to demonstrate, in real conditions, how to improve the sustainability of new and existing urban districts and how to foster the transfer of knowledge and best practices in the field of urban planning, for example, through the European Urban Knowledge (EUKN) and Energy Cities Networks. Several pilot urban neighbourhoods, often set themselves up as “sustainable”, were developed or retrofitted in this context. They received significant media coverage, and they were widely praised as best practices in terms of sustainable urban planning and low energy architecture. However, these case

studies are often presented in a descriptive way, and they are not analytic enough to allow one to compare these neighbourhoods, learn from them, disseminate knowledge and turn to good account these experiments. In this context, the paper proposes a rereading of 8 well-known examples of sustainable urban design in an analytic way that is more then descriptive. The approach adopted is intended to identify invariants in the diversity of practices to facilitate the comparison between case studies and to highlight achievement conditions and common characteristics that could be reproduced to improve current and future urban projects. Every urban project is, in fact, strictly linked to its context, and systematisation or simply the copy-pasting of a project from one context to another is not the aim [7].

2. SUSTAINABLE NEIGHBOURHOODS 2.1. The district scale The sustainable neighbourhood can be considered the meeting point between the individual sustainable building and the management of a sustainable city, which are two fields in which actors have evolved independently for a long time [8]. Thus far, this intermediate scale has been mostly neglected in building energy analyses, whereas decisions made at the neighbourhood scale have huge consequences on the performances of individual buildings and the transportation habits of the inhabitants [9]. Moreover, collective infrastructure (e.g., heating networks) is often more efficient and less expensive than equipment intended for individuals [10]. The neighbourhood is more homogeneous than the city and constitutes the ideal scale at which to experiment with new technologies and methods to improve urban sustainability [11].

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Finally, the urban fragment is large enough to guarantee the transversality that constitutes the core of the sustainable development and is small enough to more easily mobilise inhabitants and gain their participation in the project. 2.2. The case studies The paper focuses on six new and two retrofitted sustainable districts to allow a range of development situations to be explored. These case studies are chosen for one main reason: the literature available (mostly through websites and information centres) and the publicity surrounding them, which tends to highlight their exemplary nature as far as urban sustainability is concerned. These case studies were built 10 or 15 years ago, which gives us enough time to assess the mid-term effects. Due to the restricted length of the paper, only the main characteristics of the projects (context, number of dwellings and area) are summarised below. More detailed information will be included in the presentation / poster: - [BO] BO01 in Malmo (S) is a new urban district built in the framework of the European Building Exhibition (City of Tomorrow). It comprises, in the first stage, around 600 dwellings on 9 hectares. New technologies are used to demonstrate expertise and change the reputation of the city. - [HS] Hammarby Sjöstad in Stockholm (S) is a 200-hectare former harbour transformed into a sustainable neighbourhood (10,000 dwellings) in the outskirts of Stockholm that lacked new highquality dwellings. - [BZ] BedZed in Sutton (UK) is a new very low energy-consuming mixed-use community (2 ha, 82 dwellings and offices) built in the outskirts of London by a private developer and an architect involved in environmental topics. - [KR] Kronsberg in Hanover (D) is a new district built for the 2000 World Exposition to promote high environmental quality and demonstrate new technologies. It comprises about 6,000 dwellings as well as shops and offices on 150 hectares. - [FR] Vauban in Fribourg (D) is one of the most famous sustainable districts. It comprises, in the first stage, around 5,000 inhabitants and 600 jobs (38 hectares). The project aims to build a city district in a co-operative, participatory way and in line with ecological, social, economical and cultural requirements. - [EL] Eva-Lanxmeer in Culemborg (NL) is a new green neighbourhood initiated by a foundation active in environment. It comprises around 250 houses (14 ha). Its main originality is to promote the constant involvement of the inhabitants. - [VS] Vesterbo is a retrofitted neighbourhood in Copenhagen (DK). Environmental techniques are particularly advanced in the Hedebygade urban fragment (280 dwellings) that was very dense and socially disadvantaged. - [AU] Augustenborg in Malmo (S) is a retrofitted social district (1,800 dwellings) built in the 1950s and mainly inhabited by disadvantaged sections of the population. The main aim is to promote a better quality of life to the inhabitants without increasing the rent.

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In the rest of the paper, these neighbourhoods will be identified by the two capital letters in square brackets to facilitate readability.

3. ANALYSIS AND MAIN RESULTS The analysis focuses on production processes more than on detailed facts and figures to identify the main barriers to expansion and to highlight characteristics and conditions that could foster and generalise the development of more sustainable projects. This analysis is organised around five main topics: the urban context and favourable conditions, the objectives in terms of sustainability, the achievement conditions, the financial arrangement and commercialisation and, finally, the environmental performance, its evaluation and its monitoring. 3.1. The context and the favourable conditions Cities that developed “sustainable districts” were not necessarily very active in pursuing environmental policies before the beginning of the project, even if some of them were already involved in European networks or were implementing Local Agenda 21, as Fribourg, Copenhagen and Malmo did. The sustainable neighbourhood is thus not the operational implementation of former and ancient policies; instead, it is often used as a starting point to initiate, develop and communicate new sustainable local policies. Several districts were initiated and developed in the scope of a worldwide event ([BO], [HS], [KR], [VS]). This showcase is mobilised to foster the adherence of private developers, future inhabitants and especially financiers and to widely demonstrate national or regional expertise. The sustainable neighbourhood is mobilised to promote a region but also to change the image of a city, or at least a part of it. That is the reason why several projects were developed on former Brownfield (former army barracks in [FR], harbour Brownfield in [BO] and [HS], colliery in [BZ], [VS] and [AU] suffered from a bad reputation). The neighbourhood is thus expected to become a driving force in the city’s overall development as a sustainable city and in thwarting urban sprawl. The high quality of the dwellings and public spaces is presented as a breaking point with the past. However, the sites on which these sustainable neighbourhoods are developed, even Brownfield, present strong potentialities: the level of accessibility is good or has been improved before the building of the district, particularly due to tramway routes ([FR], [HS], [AU]). Neighbouring districts are used to supply services, jobs or shops. Even if the mix of functions is often emphasised, activities located in the new or retrofitted districts are only dedicated to their inhabitants (local meeting centres, laundry, etc.). The most important point is that land property is public (except in [EL], which is a private initiative), which enables public authorities to more easily force private developers to respect their conditions as far as density, energy and environmental performances and public space are concerned. Finally, this land property policy enables a sum of money to be

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

available quickly when the fields are sold and to use this money to partly finance infrastructure works, including transportation and urban networks. 3.2. The objectives in terms of sustainability The objectives in terms of sustainability are ambitious, especially as far as energy consumption is concerned; the sustainable neighbourhood aims to vastly reduce consumption and greenhouse gas emissions in comparison with neighbouring districts (60% in [KR] or 50% in [BZ] and [FR]), to supply the energy needs of the community using local renewable resources (up to 100% in [BO]), or to become self-sufficient in [EL], even in terms of the production of food. There is a huge will to demonstrate new competences and to break with traditional practices. Consequently, the environmental approach is pluralistic and mainly concerns energy but also water waste (up to 12 different kinds of waste collected in [BO] or [VS]), mobility and transportation, biodiversity and materials, among others. “Low technologies” and “high technologies” are mobilised to fulfil the objectives as well as to demonstrate and test new technologies in real conditions. To systematise technical solutions for the whole project is not an aim in these sustainable neighbourhoods. The economic and social points of view are often neglected in new developments, most likely because European and national grants were mainly oriented towards environment in the nineties [12]. Although the social dimension of a sustainable project cannot be reduced to the question of the affordability of the dwellings, a minimum percentage of social dwellings is imposed in the specifications. Renovation projects seem to pay more attention to disadvantaged population even if “gentrification” cannot be avoided. The will to break with traditional practices is also obvious in the urban forms promoted: collective dwellings, urban linear blocks oriented toward the south or open housing blocks, high density mixed together with large green spaces, the repartition of private and public spaces, green flat roofs, the use of colour or the visibility of the water cycle, among other elements. This very specific urban form is developed to create a new offer, it is easily identifiable, and it is used as a marketing argument to facilitate its promotion and to differentiate it from more traditional urban projects. The sustainable district is thus mobilised as a marketing argument, and the environmental aspects help to produce economic value and social valorisation. 3.3. The achievement conditions The break between traditional practices and the sustainable district is also carried out as far as achievement conditions are concerned. Three specific kinds of processes can be highlighted. On one hand, in a “top-down” approach, public authorities have the leadership and manage the project ([BO], [KR], [HS], [VS], [AU]). On the other hand, Fribourg and Eva-Lanxmeer have adopted a “bottom-up” approach initiated by citizens involved in the development of their own districts ([FR], [EL]). In those two cases, a group of future inhabitants

develops the main lines of the project and then tries to interest public authorities and private developers to gain financial help, subsidies and building authorisations. More rarely, the sustainable neighbourhood is initiated and managed by a private developer [BZ]. The operation arrangements are more complex, and the number of actors rises in comparison with traditional urban projects. Experts and future inhabitants are often mobilised as active actors in the arrangements to gain their adherence and legitimise the project. Network developers are also involved in the early stages of the project, because numerous new technologies are used. This is also a new challenge for construction professionals, who are confronted with new constructive techniques or materials. To generate professionals and to control quality is thus crucial in guaranteeing good execution and desired performance. Existing regulations are not adapted to these new types of developments. Several dispensations were needed to build these districts, particularly as far as the urban form is concerned. Again, the environmental exemplarity of the districts is used by the developers to gain dispensations. New tools are developed and used to accompany the developments. For example, a quality charter was developed in [BO], and developers who intervened had to respect at least 10 of the 35 environmental points proposed to guarantee urban density, architectural diversity together with high environmental quality and biodiversity. In Hanover [KR], a general plan defined the main goals chosen for the neighbourhood’s future development. On this basis, a precise tool was used to gather specific objectives and requirements applicable to private developers, land buyers and future inhabitants. The turnaround time to complete a sustainable neighbourhood is comparable to standard urban projects (from 7 to 10 years between the first contacts and the completion of the project). However, due to the complexity of the operation arrangements, the high number of actors involved in the process and the innovation carried out by the project, time is used differently. Preliminary talks, dialogue and elaboration phases that intervene before the construction take more time and are crucial to guarantee the quality of the development, define new norms and standards and to perpetuate agreements in the long term. Beginning negotiations early in the process is also common in the Netherlands and the United Kingdom, whereas in France and Belgium, especially in the Walloon Region, negotiations and redirecting tend to occur later, even as late as the building stage [13]. If this specificity allows the gaining of a large consensus and guarantees the project’s higher quality before the building of the district, it can also lead to defects, especially if, as in [BO], the building phase is shortened to adhere to an overall time limit. To avoid long turnaround times, several stages (operational and financial arrangements, incidences evaluation, etc.) were conducted simultaneously in [KR] Finally, communication is a key element in the production process of a sustainable neighbourhood.

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Forums [FR], foundations [EL] or communication centres ([VS], [KR]) are opened to create a link between the different categories of actors and to build a picture or common representation of the project, which is useful in gaining the adherence of private developers and future inhabitants. Four types of communication can be highlighted: information for the public, which is legally mandatory; the consultation (citizens are consulted but public authorities have no obligation to take the results into account); the dialogue (public authorities gather the public opinion in a more participative process, improve the project and re-submit it to the public) and, finally, the co-decision or co-production in which public authorities invite the public to participate in the design of the project. After the completion of the project, forum and information centres are created to inform citizens and future buyers, to heighten public awareness and to form the inhabitants to their future dwelling. Indeed, new technologies are used in those neighbourhoods and must be clearly explained to the inhabitants to be used correctly. 3.4. The financial commercialisation

arrangement

and

The cost of the sustainable districts is high. The question of how to finance the overinvestment is therefore crucial and must be settled in the first stages of the procedure. The return on investment is longer than usual, which is not compatible with the short-term logic of private developers. The studied projects are thus dependent upon public subsidies, which reduce the reproducibility of these experiments (up to 95% of public money in [VS], 16 millions € from the city and 32 from the state in [BO]) and question the social equity of these strategies (is it fair to concentrate so much money on limited projects?). The strategy adopted consists of first obtaining subsidies labelled as having high environmental quality. They provide an environmental identity to the project and facilitate additional financing. European funds, even if limited, are also important to legitimise the project. The final arrangements are thus extremely complex because they are based on multiple sources. This complexity has repercussions on the technologies used in the project because subsidies are often thematic and directed to solar energy, urban networks or energy savings. Another solution to finance the overinvestment and reduce the non-commercialisation risk in the sustainable districts is to propose high-standing types of dwellings or to develop a new offer dedicated to a few privileged people (very large dwelling, numerous high-quality external spaces, high-tech equipment, etc.) that can be sold at higher prices but reduces the social balance in the district. This overinvestment also has repercussions for the environmental quality of the project. Indeed, private developers considered these new products to be risky as far as non-commercialisation is concerned. and even if the partnership and the financial intervention of public authorities reduced this risk, they insisted on reducing expected environmental performances. The maximum heat consumption

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proposed in [KR] was increased by 10% (55 kWh/m².year instead of 50). Several environmental targets proposed in the [BO] charter were abandoned at private developers’ request. Finally, we have identified a last type of additional cost in the sustainable district: the management costs. The numerous public spaces must be maintained, and the new technologies need more attention than traditional ones; this constitutes an additional cost. This cost may be monetised, or it may not be; for example, inhabitants may be asked to spend a few hours each month to maintain public spaces ([EL], [FR]). 3.5. The performances and their evaluation Several types of quality controls were used during the building stages. In Hanover [KR], quality controls were decided, planned and formalised early in the process and set with very precise and detailed specifications. On the contrary, the quality charter used in [BO] only imposed 10 of the 35 environmental specifications but did not provide any sanctions in the case of non-adherence. In [EV], inhabitants, helped by experts, were in charge of quality control during the building phase. Monitoring the performance of the neighbourhood during its use is also important in checking the adequacy between initial requirements and measured results. Sensors and personal meters are thus used in several neighbourhoods, which allow the household to follow, in real time, the evolution of energy and water consumption. Indicator systems are developed and used. Unfortunately, these procedures need time and money and, in many cases, the monitoring of these systems is abandoned several months or years later because of the lack of money dedicated to this task. Moreover, even if the measured performance following the completion of the studied projects is better than standard requirements, it is not always as positive as expected because the behaviour of the occupants was not accounted for in the previous forecasts [14]. In [BZ], for example, measured consumption varies from 1 to 6 according to the household [15]. In Hammarby, the high level of the equipment (especially in the kitchen) that is furnished to the inhabitants to improve the quality of the dwellings leads to huge energy consumption, even if heating loads are reduced. Finally, new technologies are sometimes difficult to understand and difficult for inhabitants to assimilate, which can reduce the expected performance. This is especially true in retrofitted projects because inhabitants are not always looking for changes in their habits or in neighbourhoods aiming at very high quality; these projects also attract wealthier people more interested in the neighbourhood’s proposed quality of life than in its sustainable aspects. On this subject, neighbourhoods promoting a “bottom-up” approach ([FR] and [EV]) present better performance because inhabitants have been involved since the beginning and have chosen this kind of neighbourhood specifically for its environmental quality. Another trend highlighted by the experiments is that performance is difficult to maintain in the long

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

term. Solar panels in [AU] were removed after a few years because they were out of service. The cogeneration and water treatment devices in [BZ] were over-dimensioned and are no longer functional. Finally, we can highlight that, even if innovation and high quality are promoted, simulation tools were not used to improve the conception of buildings or to anticipate energy requirements. 3.6. What is reproducible and how? The analysis presented in the previous section allows us to highlight three kinds of reproducibility in the production process of a sustainable district. The first type is a “step-by-step” reproducibility within a specific neighbourhood; innovations are tested in one phase and then improved and reproduced in the following phase by trial and error (e.g., the four-phase building process in [EL] or the resolution of the thermal bridges in [KR]). This learning is important in building knowledge, especially in a field experiencing much innovation. The second type of reproducibility is the “adjustment”; the management is adapted and adjusted during the evolution of the project according to the experience gained and the external conditions. The last type of reproducibility is “learning”, and it can take three different forms: the duplication of a practice from one neighbourhood to another (the experience gained in [FR] has been used to develop a second sustainable neighbourhood in the city), the sectional diffusion of an innovation (the ENVAC sustainable waste collection system tested in [BO] and [HS] is now used in other European cities) or the duplication of a model (the BedZed model developed and tested in the United Kingdom should be implemented in emerging countries). This analysis confirms the iterative and adaptive nature of the production processes of sustainable neighbourhoods [16] and can also be applied, at a larger scale, to every innovative process in the field of urban planning. We can finally highlight a more particular form of diffusion of the sustainable neighbourhood. The pilot experiments are sometimes mobilised by citizens as a means of applying pressure on public authorities to better account for environmental quality and sustainable development in a particular local urban project (e.g., Rungis ZAC in Paris).

4. APPLICATION OF THE SETTINGS GRID This section aims to collate the production processes of the studied neighbourhoods with the reality of a Belgian dwelling project through the settings grid highlighted from the previous analysis. 4.1. The case study The case study is the Baviere housing project. It comprises about 600 new dwellings built on an urban site (4 hectares) located close to the centre of Liège (Belgium), in the Outremeuse neighbourhood. The site was former occupied by a hospital and has been a Brownfield for several decades, because even if several urban projects mainly oriented towards services were studied, opposition or financial

arrangements led to the abandonment of the projects. In 2005, the public authorities, with the agreement of the land owner (private society), decided to organise a competition to find a team able to develop a new project on the site. At the end of the process, Himmos’ project was selected. This case study has been chosen because it presents several common characteristics with the studied neighbourhoods: a programme mainly oriented towards housing, high-quality public spaces and a few services, a clear dedication to sustainable development (as written in the specifications edited by the public authorities), a desire to create a new reputation, achievement in several stages, a call for investors and planners, an urban form promoted in the winning project and a pluri-disciplinary team, among others. Finally, even if the project has been delayed indefinitely since the last economic crisis in 2009, large urban projects are fairly rare in the Walloon region. Information about this project was gathered through interviews with the main actors of the project (public local and regional authorities, neighbours, architects, etc.) and the analysis of legal texts (specifications, legal notices, etc.). 4.2. The comparison The comparison between the sustainable districts and the Baviere project allows us to highlight points of convergence and divergence. Convergence mainly deals with two themes: the characteristics of the site on which the district is planned (good accessibility, Brownfield to redevelop, etc.) and the urban form promoted (in rupture with traditional urban forms met in Liège). The private developer, who was already active in the Netherlands and in Flanders, used this new urban form to construct a new high quality picture to facilitate the project’s commercialisation. Together with the public authorities’ attention to sustainable development and the project proposed by the architects (energy consumptions in the project are, for example, lower than the legal requirements), conditions were gathered to produce a new district more aware of environmental quality than traditional urban projects, even if developing a sustainable neighbourhood was not an aim. Unfortunately, points of divergence explain why it was not the case. The project is currently stopped because of the last economic crisis. However, if financial sources had been more diversified or if subsidies had been gained, the financial arrangements would have been more robust and would perhaps have weathered the crisis. Moreover, information and communication about the project, even if it were somewhat more pronounced than the legal requirements in the Walloon region of Belgium, did not lead to a large public consensus around the project, nor did it stabilise the process. Finally, existing regulations are not adapted to new technologies; for example, using rain water in the toilets requires a dispensatory, the resale of the energy produced in the district is not already a common practice, and a fixed number of parking

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places must be planned when a new development is built, which is not necessarily compatible with mobility aims.

5. MAIN RECOMMANDATIONS The following main recommendations are highlighted from the previous analyses and could help to build more sustainable urban projects: - Information, formation and public awareness are crucial to mobilise citizens to promote sustainable development and to gain their adherence to this aim. - Social quality and economical viability are also part of sustainability and must not be neglected. - The overinvestment linked to more sustainable project is a reality but must not be reported to the final buyer thought the high quality of the dwellings. - Thinking in terms of global costs is useful because the reduction in charges quickly compensates for the overinvestment. Public-private partnerships can also help to better split the risk. Green loan, third investors, etc., exist and should be investigated - The legal framework and requirements need to be adapted to new technologies and goals. A more proactive attitude must be adopted by the public as far as sustainable development is concerned. Public authorities must take leadership in urban projects (namely, through land ownership) and impose more strict requirements on private developers by putting them on concurrence to improve the quality and environmental performance of a project. - Environmental requirements should be added to the specifications, which must specify clear objectives and expected consumptions. - Controls are necessary to ensure that initial requirements are respected. It is better to initiate quality upstream and to control it downstream.

6. CONCLUSIONS In conclusion, our study of the main characteristics and conditions that allowed the achievement of several sustainable neighbourhoods in Europe and the confrontation with a Belgian housing project has highlighted the demonstration nature of these projects. It has emphasised fundamental qualities to promote more sustainable urban districts and faults to avoid (social aspects, high prices, etc.). Reproducing exiting “pilot” experiments is difficult because of the exceptional conditions that were gathered (especially as far as the financial arrangements are concerned). However, these experiments are useful because they have proved that it is technically possible to retrofit and build more sustainable urban projects. The challenge is now go out the exception logic carried out by these experiments and to put the knowledge gained to good use for our current and future urban projects. Urban sustainability must become the rule and not the exception and must be reached at more affordable prices because technical solutions exist and have proven their appeal. However, the most crucial goal seems to simultaneously heighten public

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awareness of the importance of our lifestyles and behaviours. It is only by combining innovation, technology, good governance and citizens’ sensible behaviour that it will be possible to draw a more sustainable future and to provide an appropriate response to the global challenge of climate change.

7. ACKNOWLEDGEMENT This paper is based on a master’s thesis carried out in the Advanced Master in Urban and Regional Planning (University of Liège, Belgium). We thank the professors who monitored and evaluated it.

8. REFERENCES [1] UNFPA – United Nations Population Fund –, New York, The State of World Population, 2007. [2] D. Robinson and C. Quiroga, Sustainable masterplanning in practice. Proc. CISBAT Conference, Lausanne -Switzerland (2009), 397. [3] WCED – United Nations World Commission on Environment and Development – Annex to General Assembly document A/42/427, 1987. [4] European Conference on Sustainable Cities & Towns, Aalborg, Denmark, May 1994. [5] Commission of the European Communities, Green paper on the urban Environment, Commission to the Council and Parliament, Brussels, June 1990. [6] UNFCCC – United Nations Framework Convention on Climate Change – Rio, 1992. [7] M. Roseland, Sustainable community development, Progress in Planning 54 (2000), 73. [8] P. Lefèvre and M. Sabard, Les écoquartiers, Editions Apogée, Mayenne, 261p. [9] E. Popovici and B. Peuportier, Using life cycle assessment as decision support in the design of settlements. Proc. of the 21th PLEA Conference, Eindhoven, (2004). [10] C. Hanson, The cohousing handbook. Building a place for a community, Hartley & Marks Publishers, USA, 1996, 255p. [11] C. Charlot-Valdieu and C. Emélianoff, Les apports de la démarche Agenda 21 local à travers deux thèmes d’analyse, Rapport pour l’ADEME et le CSTB, 2000. [12] M. Lemonier, Eco-quartiers; Les pionniers font école, Diagonal 178 (2008), 41. [13] B.Glasson, P. Booth, Negotiation and delay in the development control process: case studies in Yorkshire and Humberside, Town Planning Review 63-1 (1992), 63. [14] C. Bech-Danielsen, Ecological Reflections in Architecture. Architectural design of the place, the space and the interface. The Danish Architectural press, Copenhagen. [15] F. Faucheux, Proc. Mise en oeuvre et évaluation des écoquartiers, Fondaterra, Paris (2009). [16] CEAT – Communauté d’études pour l’aménagement du territoire – Lausanne (2008).

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011)

th xxx-x-xxxx-xxx-x - ISBN (USB @ Presses universitaires de Louvain 201113-15 July 2011. PLEA 2011 - 27ISBN Conference on Passive andstick) Low xxx-x-xxxx-xxxx-x Energy Architecture, Louvain-la-Neuve, Belgium,

Tracking Design and Actual Energy Use: CarbonBuzz, an RIBA CIBSE platform Judit KIMPIAN1, Sophie CHISHOLM2 1&2

Aedas, London, UK

ABSTRACT: CarbonBuzz is a collaborative research project between the Chartered Institution of Building Services Engineers (CIBSE) and the Royal Institute of British Architects (RIBA) to engage industry and government with closing the gap between forecast and actual building CO2 emissions. It is the result of joined-up thinking between architects, engineers, professional bodies, policy makers and academics. Its aim is to improve the awareness of building performance indicators amongst those who play a major role in the design and construction of buildings. Keywords: Design tools and methods, sustainability benchmarks, energy use, carbon reduction, unregulated

1. INTRODUCTION As one of the largest UK architectural practices, we have introduced annual carbon audits of our projects and operations with the aim of setting practice-wide carbon emissions targets. The process of tracking the energy consumption of our projects from design to operation has highlighted a prevalent industry gap between expectations and outcomes. In response we have set in motion a host of research initiatives including CarbonBuzz. In partnership with University College London (UCL), the Building Research Establishment (BRE), Aecom, Feilden Clegg Bradley Studios (FCBS) and XCO2Energy, we set up a joint research programme between the Royal Institute of British Architects (RIBA) and the Chartered Institution of Building Services Engineers (CIBSE) in 2007. Now an RIBA|CIBSE platform, this project seeks to make meaningful energy consumption data available in the public domain to support ‘live’ benchmarking and analysis of the effectiveness of carbon-reduction measures. The platform also allows users to visualise the energy consumption of buildings in such a way that it draws attention to the end uses that are responsible for the gap; the worst offenders being the end uses that are not included in the compliance calculations and are therfore often overlooked in design. The Partner Group was awarded a three-year match funding grant in 2009 and is currently working to broaden the reach of the platform to professional bodies representing the interests of landlords, tenants, surveyors, facilities managers as well as local and central government bodies. CarbonBuzz’ Steering Group, formed over 2010, comprises over 15 member organisations spread across these interest groups (see Fig.1). The role of this group is to review the platform development to ensure that the data management and analysis is seamless across sectors and disciplines. Currently, energy use information is collated across a confusing range of reporting standards – throughout a building’s life-

cycle. The current discrepancy between different types of energy certification (Energy Performance Certificates & Display Energy Certificates), planning criteria, building regulations and carbon taxation has been identified as a fundamental barrier to achieving low-carbon performance in use. [1] As an easy-touse dissemination channel for low-carbon case studies, CarbonBuzz is becoming an authoritative database for detailed energy use information to support an evidence-based approach to investment in low-carbon solutions. CarbonBuzz is publishing data gathered through the Carbon Trust’s Low Carbon Buildings Programme [2] and Low Carbon Buildings Accelerator [3] as well as the Technology Strategy Board’s Building Performance Evaluation programme. The platform will help inform investment in management and design measures tailored to address actual consumption by providing feedback to users as to the effectiveness of a broad range of lowcarbon measures in use. In doing so it will open up a vast range of opportunities for designers to address occupant behaviour and user satisfaction. The website will also offer tools to manage portfolios and demonstrate year-on-year carbon savings. By inviting platform users to go beyond compliance estimates, CarbonBuzz helps organisations address ‘unregulated energy use’ – occupancy-related consumption that can account for well over 50% of a building’s energy use. The platform, www.carbonbuzz.org currently enables users from all construction sectors to benchmark and track project energy use from design to operation, through a visually engaging online interface. It also encourages users to share emissions data in the public domain. Forecast and actual energy use estimates can be compared against industry benchmarks as well as live data from other users’ projects anonymously.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 1: CarbonBuzz diagram including Steering Group members.

2. BACKGROUND UK buildings represent some 45% of the UK’s total delivered energy consumption. [4] There has been some progress in achieving carbon reduction however it is difficult to pinpoint what measures to attribute this to; economic decline, changes in policy, something else or a combination of drivers. It is also necessary to analyse which measures in a low carbon case study have been the most effective. A more thorough understanding of all of these will allow for better forecasting. Lack of real world data is the major barrier. By hosting such data and communicating trends in the database, CarbonBuzz can provide much needed evidence to support policy as well as design and portfolio decisions. A major influence on the project has been the work carried out by the Usable Buildings Trust (UBT) on the mapping of energy consumption of buildings in use (PROBE) [5] as well as the methodology behind CIBSE’s Energy Use Benchmarks (TM46). The former provides robust evidence of the gap between design estimates and operational energy data which has been recorded to be 2 or 3 times greater. [6] The latter forms the backbone of the UK’s Display Energy Certification (DEC) which is the only currently mandated metric in the UK that relates to a buildings’ actual CO2 emissions. Applicable to all 2 non-domestic public buildings above 1000m since 2008, there is a gathering momentum to extend these to the full non-domestic, commercial building

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stock in the coming years. Linking other reporting mechanisms to the DEC system and referencing the DEC methodology into design has been a key challenge for CarbonBuzz. DECs are the postcompletion relative of the Energy Performance Certificate(EPC). Based of the Part L calculation, the EPCs are a record of a building’s asset rating NOT its estimated energy consumption, often resulting in confusion. The huge discrepancy between these two documents provides yet more evidence of the problem the CarbonBuzz seeks to address. The source of the confusion is that mandatory design calculations required for compliance with Building Regulations and EPCs currently measure a percentage improvement against a notional target, but these calculations do not fully address factors relating to building occupation and operation. With these calculations providing the bulk of design stage ‘forecasts’ the result is that design calculations appear optimistic when compared to actual consumption. Display Energy Certificates measure actual consumption – i.e. all the energy used in a building. This mismatch between reporting design and actual performance is not only unhelpful to track performance; it also means that mandatory design calculations do not highlight operational risks to energy consumption at the design stage, increasing the risks of higher than expected consumption. Figure 2 is a summary of design vs. actual energy consumption data by sector from the platform.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

With many new buildings and refurbishments falling short of low carbon expectations there is a need to develop more robust methods of understanding actual performance at the design stage, which take into account operational factors. To develop this, the industry needs up-to-date data and feedback from new buildings as well as refurbishments. The CarbonBuzz CIBSE|RIBA Platform invites users to estimate some of the operational risks at design stages and collects and hosts detailed CO2 emissions data. Funded jointly by industry and the Technology Strategy Board it is developing an online interface to provide better feedback on the impact of occupants on building performance. CarbonBuzz provides a framework for the compilation of energy use and CO2 emissions data reporting standards spanning acquisition to operation and facilitates their broad brush comparison. The disparity between these standards – Planning, Part L, EPC, DEC, Carbon Reduction Commitment, BREEAM - presents a major challenge to the construction industry due to the countless metrics they employ to describe energy consumption and carbon emissions. As regulatory mechanisms and broadly recognised design standards they must be traversed in order to realise a project. Carbonbuzz provides the interface for their easy alignment.

3. DESIGN VS. ACTUAL CONSUMPTION

emissions based on fixed occupancy and operating hours and do not take into account a broad range of factors affecting actual consumption. This issue has been highlighted in other reporting standards across the Globe. Global sustainability standards, such as LEED and BREEAM have been criticised for rewarding building designs that do not have to demonstrate how they address the operational risks of low-carbon performance. The diagram below (Fig.3) is the first cross-disciplinary description of what is missed at design stage when using only compliance calculations; coined ‘unregulated energy consumption’ because they are beyond the reach of current UK Building Regulations. First and foremost is increased energy consumption due to differences in as-designed and as-built which could be caused by a number of things, not least the installed envelope performance, product replacements or other cost engineering measures. The remainder of the energy consumption ‘gap’ consists of four sections that are dictated by the way a building is inhabited; appliances and IT, extra occupancy and operating hours, the quality of the facilities management and any special functions integrated into the building such as trading floors, server rooms or special equipment such as kilns and furnaces. The consequences of these unregulated energy loads vary. IT and appliance loads present a high risk if coupled with poor building management which often means that equipment is left on 24 hours. Extra occupancy in itself represents a

Figure 2: Design vs. Actual data by sector from the CarbonBuzz database

Figure 3: CarbonBuzz energy bar highlighting the gap between regulated and unregulated energy consumption.

The biggest and arguably most onerous misnomer is the term ‘design forecast calculation’. According to feedback received from CarbonBuzz users and via the Stakeholder Engagement interviews, Part L (Building Regulations) calculations are widely regarded as forecasts. As the only mandatory calculation carried out by a design team this leads to obvious misrepresentations. Part L calculations only describe likely annual CO2

relatively low risk but when related higher equipment loads are not managed well they can result in high consumption. A building’s operating hours and the facilities management act as multipliers across the building’s energy consumption as a whole including fixed building services such as heating, cooling and ventilation. Based on data gathered in the CarbonBuzz platform, school/education projects are particularly

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 4: Energy bar diagram showing end use breakdown.

optimistic about likely consumption – with the median for actual consumption being approximately five times of what is stated during design. There are a myriad of safety nets that are employed from building acquisition through to occupancy that can decrease this gap, beginning with a detailed brief that takes into account true habitation of the building. This is a difficult task in the commercial sector where developers often have to cater for a number of unknown occupiers. If this exercise is performed properly, it will minimise the risk of unexpected consumption from the ‘appliances and IT’ and the ‘special functions’ sections of the energy bar. Predicted energy consumption calculations must be constantly adjusted throughout

Following handover Soft Landings monitors building performance and engages occupants to gain a greater understanding of their new environment. This encourages ownership and results in a greater likelihood of the building being used according to design intent. CarbonBuzz draws attention to these factors by gathering information on energy use and building performance based on how energy is actually spent in a building – i.e. according to end uses. (Fig.4) By representing this as a simple bar diagram during design and following completion means that a very quick assessment of unexpected energy consumption areas can be made and measures can be taken to address this.

Figure 5: CarbonBuzz energy dashboard for Stockley Academy

For example, in the case of Stockley Academy in West London, the building’s forecast heating consumption was actually higher than the achieved outcome (figures 5 & 6). This indicated that the Thermodeck system in place was working better than expected. This was supported by interviews with facilities managers and building occupants who felt comfortable during the winter months and who confirmed that the systems were easy to manage. However, all the carbon savings were used up by the excessive electrical energy use, as reported by the electricity bills. Nevertheless, without the end use breakdown we at Aedas could not verify whether the excessive consumption arose from unexpected use of lighting or appliances. Whilst this is a very common occurrence, only the prompt monitoring of Building Management Systems (BMS), good sub-

any minor amendments to the design and throughout the construction stage. This will account for the design versus as-built extra energy consumption. Building management needs attention at all stages of the process. Correct sizing of building services and systems based on full energy and energetics calculations and thorough consideration and implementation of user controls are imperative. The exercise that is often overlooked under tight programmes is the Soft Landings process. [7] During a dedicated commissioning period building managers are trained to use the installed equipment and guided through the initial period of use to fine tune the systems and eliminate inevitable teething problems.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

risk of unexpected energy consumption is going to be. The importance of this feedback is three-fold and is summarised best by Leaman, Stevenson and Bordass 2010 as contributing to the improvement of: the studied building, the services of those who provided it and the wider knowledge base. [6]

Figure 6: Stockley Academy, Aedas

metering or a detailed building energy survey can identify this. This diagram illustrates the earlier point; if the appliance schedule changes from design to operation, the unregulated section of the energy bar will grow. However, when the operating hours are extended beyond their standard benchmark, the heating, hot water, lighting, cooling & plant and unregulated sections of the energy bar will be affected. Part L2 of the Building Regulations for England and Wales sets out a requirement for 90% of a building’s end-use energy consumption to be submetered. In practice this is not implemented or enforced. In the rare cases it is carried out, the setup is installed with only compliance in mind as opposed to being designed for useful data-harvesting. As users become involved in the CarbonBuzz platform, there is a growing realisation about the drivers for this piece of legislation. The inconsistent implementation of submetering has led to a situation where gathering and monitoring consumption requires specialist expertise and regular site visits, is therefore perceived as costly and is rarely carried out. The connection between design quality, occupant comfort, metering and bills is therefore often overlooked by designers who traditionally do not receive feedback on how a building performs in use, unless there is a serious problem. In providing a visual feedback of potential consequences of these factors CarbonBuzz not only helps designers reduce risk but gathers data on the scale of this risk over time. Current methods of actual energy consumption monitoring do not crossreference the data with other measures. This results in missed opportunities to expand our energy reduction arsenal and our understanding of the efficacy of investment in renewable energy generation. Over the next two years, CarbonBuzz will develop increased capability to track these changes from design to occupancy and compare the relative energy bars. This functionality will be developed hand-in-hand with the ability to perform a sensitivity analysis on a project, where users will enter building information and identify risk factors to energy consumption outcomes. The higher the level of confidence that appropriate steps have been taken to address occupant-related consumption, the lower the

Figure 7: Example sensitivity analysis. Top bar: Appliance and equipment loads defined. Uncertainty over occupancy, facilities management and design execution. Middle bar: Appliance schedules and more detailed occupancy information. Level of facilities management still uncertain. Bottom bar: Level of facilities management confirmed. Possibility of extra occupancy.

4. CONCLUSIONS By providing fast visual feedback of the consequences of briefing and design decisions on likely outcomes, CarbonBuzz is drawing designers’ attention to the need to improve design integration with a building’s mechanical systems. It also highlights the importance of considering how occupants will interact with the building from the very start of a project. In this way the platform draws occupant behaviour, an often overlooked driver, into the realm of design. Whilst energy consumption is only one aspect of a successful building, the experience of the Aedas team has been that using the CarbonBuzz workflow tends to improve design integration – it allows clients and architects to ask the right questions from engineers while engineers can rapidly demonstrate the consequences of design decisions. With over 340 member organisations and over 240 projects entered, the CarbonBuzz platform has become a notable resource for the construction and property sector in the UK.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

5. ACKNOWLEDGEMENTS Craig Robertson, UCL / Aedas.

6. REFERENCES 6.1. References [1] Kimpian, J., Response to ‘Energy performance of buildings evidence and feedback’ by Lord Marland of Odstock and Andrew Stunell MP, Aedas, London, 21 December 2010 [2] www.lowcarbonbuildings.org.uk [3] www.carbontrust.co.uk/emergingtechnologies/current-focusareas/buildings/pages/buildings.aspx [4] The Chartered Institute of Building Services Engineers (CIBSE), CIBSE Guide F Energy Efficiency in Buildings, London, (2004), 260pp [5] www.usablebuildings.co.uk [6] Bordass, B. Leaman, A., and Stevenson, F. Building evaluation: practice and principles, Building Research and Information, (2010) (38) 5, pp. 564-577 [7] www.bsria.co.uk/services/design/soft-landings 6.2. Bibliography [8] Bordass W., Setting the Scene: Energy and carbon reporting, communication and benchmarking. Discussion notes for the CIBSE steering group meeting, The Usable Buildings Trust, London, 25 November 2009, 10pp [9] Bordass W., Why Display Energy Certificates make sense in commercial buildings, The Usable Buildings Trust, London, No date, 1pp [10] Bordass W., Onto The Radar: How energy performance certification and benchmarking might work for non domestic buildings in operation, using actual energy consumption, Discussion Paper, The Usable Buildings Trust, London, (2005), 14 pp [11] Bordass W., Standeven M. and Brown P., Improving the Energy Performance of Rented Buildings: Bridging the Landlord Tenant Split, Presentation, The Usable Buildings Trust and British Property Federation, London [12] CIBSE (2008). Energy and Carbon Dioxide Benchmarks – CIBSE Draft Version 3y, CIBSE, 2008 [13] Bordass, B., Bunn, R., Field, J., Jones, P. (1998). Improving Effectiveness of Energy Assessment and Benchmarking

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ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Identity of Sustainability: from technique to the sensory and experiential. Neveen HAMZA School of Architecture, Planning and Landscape, Newcastle University,UK ABSTRACT: This research argues that sustainable architecture is part of a nuance of evolution in buildings that aspires to provide a narrative of a local responce to people and climate. An architecture that combines ethical aspirations, building performative aspects of integration of renewables and passive design fusing to create an experiential building. Work Places have been at the centre of this evolution, with arsing concern that the alignment of climate and energy concerns, the knowhow of using sophisticated renewables and solar shading systems are only a technical issue that will lead to an extension of a globalized industrial and technical image of the corporate. The corporate image is often linked to an image of environmental seclusion spread by the ideologies wrongly linked to the American and European export of the „Modern‟ to the world. Here, it is argued th that the rules of thumb underlying the 20 century earlier building designs have now moved on to use more sophisticated tools in which building performance and human comfort can be predicted at design inception stage. The case studies chosen share an agenda of sustainability based on a „BREEAM‟ excellent rating but also highlight an attempt for „experiential sustainable architecture‟. The research analyzes how these corporate aspirations moved on from buildings with „no location‟ into an architectural specific to its „genius loci‟ reflecting sustainability as a sensory and experiential experience for its occupants. Keywords: sustainability, building facades, the corporate image, sensory, experiential

1. INTRODUCTION Canizaro [1] warns that theorists constructing the discourse of sustainability in architecture have rarely built a connection between the past historical practices of building and sustainability. „Like many developments in the modern era, sustainability has been seen and promoted primarily as something new, progressive, and future oriented...the result is a discourse and practice dominated by technical solutions to mostly technically framed problems‟. He advocates ‘regionalists’ as architects and theorists concerned with the manifestation of realness of places and people who live in them leading to an historical thread of concern that calls for a more environmentally responsive practice giving attention and awareness of the local place experientially, ecologically and to the local social and cultural constructs. This paper argues that designing for sustainability goes beyond regionalism and bio-regionalism, critical regionalism to a more site specific response, capturing the ‘genius loci’ in an attempt to provide a sensory and experiential environment to its occupants, while responding to local climate, site, using renewables and complying with building regulations. Case studies represented, layers the building envelope to reflect discourse that contextualizes connectedness to place, reflect sustainability by the use of art as a built cultural message, and technology as a vehicle for environmental performance and responsiveness. This notion moves away from the mere concept of technique of the ‘modern’, or the sacred fictitious geographic boundary that determines the history and characteristic of its inhabitants, and from picturesque

follies promoted by ‘‘regionalism’. The case studies present a global aspiration for sustainability but a local interpretation relevant to its site and comfort of its occupants, and hence a ‘glocal’ expression that highlights the experiential facet of sustainable architecture. TH

2. THE 20 CENTURY, THE CORPORATE IMAGE AND SUSTAINABILITY The rise of office buildings as multi-storey icons th in the late 19 century is attributed to the changing corporate and business needs and a plethora of technological advancements, the introduction of new construction methods such as steel frames, the lift, air-conditioning systems and artificial lighting. The seminal buildings that follow all offer a continuous trajectory and evolution in principles underpinning human productivity and well being, and the corporate image. It is argued in the following case studies that realizing the corporate image is underpinned by sustainability aspirations led to a developed strong visual message that aspires to achieve a sensory experience for its occupants as well as its outside viewers. However, it is the corporate image as reflected in the ‘modern’ style that brought with it a misinterpretation of many of the movement’s architectural values. The Seagram building, and Sears towers among others were used as an icon of detachment from their environments. The Seagram building in 1958 was seen as representative of the Seagram Corporation, its role in markets and contemporary life. However these facade treatments were meant to create the changing reflections from these glazed surfaces and a preoccupation with

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

expressing their construction technology while moving around the buildings [2] The emphasis being on an external experience of the monumentality of the building rather than a preoccupation with what happen behind the skin. By exposing steel members that reflect the modular construction of the curtain wall that has no function for structural or indoor environmental moderation. By current standards a practice that under a sustainability lens can today be argued against, as decorative and a wastrel use of resource. With the need to export this building function to other localities came the need to transfer the image. However, case studies here will demonstrate how corporate agendas are pushing sustainability with its three pillars to the fore while emphasizing the sensory and changing experiences indoors for its occupants. The practices attached to the ‘modern’ movement had consciously disregarded its protagonist’s philosophies to respect the local environment, the ‘genius loci’ and cultural values. The role of the building envelope as an environmental moderator or a cultural message or both has been contested during the Modern movement. The flexibility of construction behind curtain walls, the ‘technique’, flexibility of large open spaces and the economic rental values superseded the original intentions and philosophies. Hitchcock and Johnson [3] in promoting ‘modern’ views that in „the 1920‟s it was maintained that modern architecture should follow the same principles regardless of „location‟ or „region‟ a notion that Walter Gropius and Siegfried Gideon were eager to dispel. Gropius stated that ‘architecture should not be conceived as a mere practical product but has to deliver „aesthetic satisfaction to the human soul‟ [4]. Gideon [5] goes further to call on the building envelope to deliver a ‘new monumentality’ in which it ‘springs from the eternal need of people to create symbols for their activities and for their fate or destiny, for their religious belief and for their social convictions. [demanded] respect for the ‘way of life’ to be studied with ‘reverence’’. However, ‘the ‘international style’ is seen as lacking stimuli, over dependence on a technological expression of construction technology and that it became a commodity reflecting an imported corporate image as in the blind transportation of image of glass curtain walls in hot regions such as the Arabian Gulf. The works of TeamX in the post-war era reflects a preoccupation with the expression of the curtain wall to the outside environment, its modularity and offsite construction. The Battlebridge, London by Alison and Peter Smithson (1972-74) follows a statement that „the building‟s position on the basin‟s edge procures a smooth continuum of wall screen into mirror image in the water, the building responds to this calmness of untroubled repose by presenting a single skin of stainless steel and glass; the layered dimension of the sky and the buildings opposite are ever changing, responding to season, weather and time‟ [6]. It is argued that the occupants’ experience and how the building skin moderates rather than separates the external environment is still unrealized

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although there is an attempt to look into the ‘genius loci’ of the site. In the early seventies, Dutch structuralists hoped to overcome reductive aspects of ‘functionalism’. Herzberger’s well cited ‘Centraal Beheer’ in Holland 1974, presented an exploration that focused on human interaction and workflow indoors to create a built form while ignoring the local outdoor context. Still daylight being introduced from the top level of an atrium like space, created in the architects’ own words a’ bunker-like labyrinth’ the building was introverted and the company had to put up sings so people can find it’s entrance. Norberg-Schulz [7] goes from there accusing „those who got stuck with the early images of a green city and standardized form, were the epigones and vulgarizeres of modern architecture‟. He alluded to the function of the building envelope as a visual message and a layer where dealing with the external environment takes a distinctive character. He laments the loss of „The character of the present day environments is usually distinguished by monotony...the „presence‟ of new buildings is very weak, very often „curtain walls‟ are used which have an unsubstantial and abstract character. Most modern buildings exist in a „nowhere‟; but live their life in an abstract life in a kind of mathematicaltechnological space‟. He goes on to warn of an ‘environmental crisis’ in which buildings don’t offer any meaningful or indeed intentional variation in engagement with its environment. The quest for an architecture that addresses all senses still carries on in Pallasmaa’s writings [8] in his pursuit for an architecture that engages all human senses, that seems to warn against the ‘globalization of bland environments to address ‟Qualities of space matter and scale which are measured equally by the eye, ear, nose, skin, tongue, skeleton and muscle‟. However, the question still remains unanswered; will architects’ responses to a sustainability agenda follow suit of the ‘functionalist’ and ‘globalized’ architecture? Will architecture present renewables as an alternative to the aesthetic of the ‘module and prefabrication’ reflecting a commitment to technique? The building envelope is where a visual statement of commitment to place and people is exhibited. Therefore it is critical to move forward from the process of renewables as an add-on afterthought to an integral visual engagement and a design language that is naturally very specific to the ‘genius loci’. It is dangerous for public acceptance of these technologies to be projected as techno-centric and ‘sustainability bling’. Sustainable buildings have to reflect a deeper expression of an engaging and memorable building experience that manifests the climatic specific context of the building, clients’ sustainability aspiration and a sensory message that enhances the well-being of occupants. It is acknowledged that delivering a sustainable building is a holistic concept that integrates the building and its services. The building’s envelope has a longer life cycle than its supporting mechanical systems and based on the plan depth can contribute to about 3040% of building energy demand [9]. The paper presents case studies with an underlying

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

commonality; they all achieved an environmental performance on a ‘Core and shell’ principle achieving a BREEAM rating of ‘very good’ or ‘Excellent’. This means that it is generally expected that once these buildings are occupied by different users with different technology demands that the energy performance of the building will vary and exceed the predicted performance. These buildings seem to share a rational anticipation of circumstantial contingencies changing internal use and layout, but still aspiring to convey a message of responsiveness and responsibility towards the environment Figure 2; the DEFRA’s Lion House 2009, Anwick, UK by Gibberd architects could be seen as a common expected aesthetic for a building with many renewable add-ons. The design architect, Raymond Gill says: “We have designed a modest building, whose aesthetic is derived from our aspirations to make it environmentally sound. We have maximised its passive sustainable potential and integrated active measures, like the PVs, to make the very best use of them in multiple ways.”

Figure 2; the DEFRA‟s Lion House 2009, Anwick, UK, A BREEAM „excellent‟ building. The aesthetic appearance gives an expected message of many inclinations to present sustainable buildings as an energy saving machine with as many renewables added to its building envelope. True that photovoltaic cells are also a visual message of a building’s orientation to the South but danger here is falling into the traps of reflecting sustainability as a set of PV cells and a wind turbine on functional core and shell buildings that could presumably be constructed anywhere! The same messages that even the pioneers of the ‘modernist’ movement warned against.

compliance. This led to a tangible collaboration between the architects and their consultants in very early stages of the project inception [10]. However, Leatherbarrow [10] rejected the notion that the development of new instruments and methods of predicting a building’s structural or environmental behaviour will radically redefine architectural practices or theories. But that attention to performance will contribute to new understanding of the ways buildings are imagined, made and experienced. Thus calling for a holistic human and technical interpretation of performance to avoid an inadequate reductive and an uncritical reaffirmation of pure functionalist ideology. 3.1. Experiencing renewables in building skins A positive relationship was established the integration of the PV array by Studio-E in their design for the Doxford Solar Park, Sunderland, UK (2000), Figure 3.

Figure 3: The PV array as an integrated feature of the South elevation.

The intention to present the renewable aspect of the facade was influenced by the environmental simulation of indoor environments leading to extending the facade higher than the building to deal with the heat stratification behind the facade from the glazed areas and from heat generated from the transparent 532 sq.m PV arrays (Figure 4). The PV array produces 75kWp with surplus feeding into the grid. The building is estimated to generate quarter to one third of its electricity demand [12].

3. SUSTAINABLE ARCHITECTURE, AN EXPERIENTIAL SENSORY APPROACH Sustainable architecture, Performative architecture, low-carbon design are all terms used to describe an intention to use current construction and environmental technologies in designing the building. The increasing computational power to predict the performance of a building not only in terms of energy reduction but also its impact on occupants and its site. Aided by a thrust in the development of building performance regulations, ‘Building Performance Simulation Tools’ found an increasing role in the design phase of buildings to demonstrate regulatory

Figure 4: Computational Fluid Dynamics CFD simulation of heat stratification behind the PV array and in atrium space

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

It is noticeable how the choice of the PV system and using the atrium as a buffer created a distinctive architectural language and internal indoor environments (Figure 5). To reduce infiltration into the atrium there are no windows on the PV integrated facade, all ventilation is supplied from windows from the office space facing other orientations. The costs of the PV array were obtained from a European Union funding as this alone would have exceeded the building’s budget. Here the building reflected a commitment to the performance aspect responding to the client’s brief and the architect’s vision of translating ‘sustainability’ in the building brief. As an early example the exterior is inclined towards the ‘technical’ although the interior is an accidental ‘experiential’.

sun’s azimuth so as to eliminate the direct solar glare. High quality internal environment, with all internal spaces designed as mixed mode systems to take advantage of natural ventilation with additional mechanical cooling and heating during summer and winter. The PV array with its 184sq.m and estimated output of 25KW creates a visual message of commitment to sustainability. No real data of its contribution to building consumption could be released and unfortunately the manufacturers had to change the whole array in 2010 as the PV cells were de-laminated. The attempt to create an experiential visually engaging environment by the automated louvers, which close completely on a sunny day to prevent glare which prevents a view out on the few sunny days in the North East of England. Automatically controlled natural ventilation was disengaged to allow for more occupants control by floor level. The curved facade was created to improve pedestrian air movement and a visual vista to avoid a claustrophobic visual experience from the imposing buildings surrounding the site.

Figure 5: interior of Building with its varied shadaows and light from PV arrays and transparent areas

3.2. The responsive skin and corporate image During the 1980s, the greenhouse effect was linked to the increase in CO2 emissions from the built environment. In office buildings the heavy utilization of energy to provide comfortable indoor environments was found to be at a profligate level of five to six times higher in a conventionally sealed envelope office environment than a naturally ventilated and lit one [13]. The following case studies are a broader translation to clients requiring buildings to reflect their sustainability policies, to providing a sensory and experiential experience through responsive and dynamic building skins integrated in a holistic performance The Devonshire building was established as flexible lab and research accommodation in the University of Newcastle Upon Tyne by Dewjoc architects in 2004 (currently Devereaux architects) Figure 6. Newcastle University (as the client) was aiming for BREEAM excellent to reflect the university’s commitment to sustainability in its research and societal responsibility. This was achieved by designing for the inclusion of many renewable systems including a PV array on the roof, an atrium with roof lights to introduce natural daylight, rainwater harvesting systems for toilet flushing and an automatic motorised Brise Soleil to the south elevation incorporates horizontal aerofoil blades. The control of the blades operates from an integral sensor automated control system. This intelligent programme allows the blades to track the

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Figure 6: the Devonshire Building completely closed in response to a sunny day.

However, it is important that these buildings are seen as successful experiments that underpin the development in current knowledge and future thinking underpinning improvements in building performance. The building facade provides a strong message of commitment to building sustainability and responds to the corporate image of a university that is positioned as a leader in research on sustainability in technology and social research Another example, The client ThyssenKrupp AG wanted their new headquarter (Q1) building (figure 7) to reflects their commitment as a company to: ‘innovations, sustainability, openness and Knowledge sharing’[13] to be constructed on an 200 year old steel manufacturing site in Essen-Germany, JSWD Architecten and Chain & Morel et Assoils won the competition in 2008. The building was occupied in June 2010. The primary energy consumption of the new buildings in the complex is estimated to be 20 to 30 % lower than the statutory requirements. There are currently only very few buildings in Germany. 1,000 square meter geothermal field on the site the loops extend to a depth of 100 meters below the earth’s surface. The geothermal ground loops utilize the heat and cold stored in the earth are used to reduce the buildings’ energy demand for heating, while passive measures of natural ventilation and solar shading

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

systems are used to further reduce demand on airconditioning systems. A 10 storey high atrium introduces natural ventilation and has neither heating nor cooling. Throughout the Quarter rainwater will be collected on the roofs of the buildings – an area of 25,000 square meters. After removal of impurities the water will be fed into the lake of the Krupp Park.

Figure 7: changing daylight levels in Q1 (top), Facades of Q1 (bottom)

The facade design is not only about providing a stainless steel mesh that traces the sun movement but also serves to give the building a distinctive skin that changes its performance in response to natural daylight levels. The electrical lighting systems are connected to sensors that dim the lights according to availability of daylight from the facade. In both cases, the interactive building skin has shading systems that are considered part of the intelligent facade systems and treatment. Their performance is measured by their ability to respond to unforeseen and changeable external climatic conditions to ameliorate their adverse effects on the indoor environments and occupants. The richness of expression is mostly created by the variable movement of light on these systems that creates indoor variability of opacity, reflectivity, transparency and colour. These variations create engagement and appreciation of these systems but, in most cases, are an accidental delightful surprise after the building is constructed. Reservations on extensive automation of the various automated skin parts have to be considered. The inherent vulnerability of these systems respond to conflicting needs of changing climate conditions on the various parts of the facade and has to respond to varying occupants needs indoors. The various parts will experience varying stresses, use and maintenance requirements. But apart from the technical reservations the experiential quality of the buildings and their reflections of their ‘genius loci’ is a promising precedent.

3.3. Increasing facade layers, Double Skin Facades as a passive measure and a cultural message Double skin facades are increasingly deployed in architectural applications, offering a passive climatic buffer zone to the building that can be utilized effectively to introduce natural ventilation indoors for higher floors while reducing noise propagation indoors and has potential of reducing mechanical ventilation loads even in hot arid climates [14]. Natural buoyancy drives out heat stratified in the gap between the two facade layers. Deployed in Willis, Faber and Dumas building (Foster and Partners, 1975), Occidental Chemical Centre in New York (Canon Design 1980) Commerz bank (Fosters and Partners, 1991-1997, Strador in Dusseldorf (Petzinka, Pink and Partners), Swiss Re Building in London (2002-Fosters and Partners) and the Leicester John Lewis Store (Foreign Office Architects, 2008). It is the later that points out to a new emerging trend of romanticism in reflecting the sustainability agenda of the corporate image and its intention to respect local history. John Lewis Partnership’s ‘sustainable construction policy’ aims at reducing its carbon footprint stated that „Our current target is to reduce CO2 emissions as a percentage of our sales by 10 per cent by 2010 (against a 2001/02 baseline) and to improve energy efficiency by 10 per cent by 2013 (against a 2003/04 baseline). An expanding business can't avoid rising energy consumption. Our sales have risen by 28% over the last five years, but we've managed to contain the Partnership's absolute CO2 emissions to 19% over the same period‟ (sustainable construction framework) [15]

Figure 8: The Leicester John Lewis facade morning (left) and night (right) facade expressions.

The Highcross complex in Leicester includes a multi-screen cinema and a 4 storey John Lewis Store. The store’s facade uses a fabric analogy expressed as a series of pleats and the patterns swirls found from an archived piece of fabric in John Lewis pays tribute to Leicester’s textile manufacturing history. However, the use of a double skin facade here might provide a bonus environmental performance rather than an integrated intentional performance. The two layers have the printed pattern directly aligned and are lit by night producing an engaging changing facade. But as the depth of the shop floor reduces the effect of both daylight and thermal transmittance from the double skin facade, this facade is performing as a decorative drape rather than an environmental moderator. It

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

allows considerable daylight levels while reducing the direct solar penetration discolouring fabrics) as the external pattern is covered with a reflecting layer. The exact alliance of the two patterns on the glass reflects direct solar radiation and direct vision to the interior as it is viewed tangentially. The facade does not provide any natural ventilation indoors which is completely air-conditioned. The facade is structurally suspended from the top of the building to reduce the supporting structural members and a distracting appearance behind the double skin. To cover the structural system the increase in its height above the building’s roof allowed the stratified hot air to be kept away from the top floor of the building. However, all this appears to be an accidental bonus rather than a planned for integration. This building was awarded a BREEAM ‘very good’ and can be seen as a new landmark to lead the way into thinking of layering a cultural message within a performative framework

4. CONCLUSIONS: This paper argues that reflecting sustainability of the building as an experiential and sensory experience found its roots in ancient civilizations and its delivery still is an ongoing aspiration. Although the first generation of the ‘modern’ movement advocated a site specific architecture, the misinterpretations of the early thinking underpins a global wide spread corporate image of buildings that are misconceived environmentally. The building fully glazed and sometimes bland facades treatment as a curtain wall that acts as a climatic separator reflects a pre-occupation with technique rather than the experiential quality of the occupants inside the building . The simulation tools available for architects today (illustrated here by the Doxford solar building) is becoming common practice and creates an opportunity to predict with a level of accuracy the indoor environments at design stage As new corporate sustainability agendas develop realizing that a sensory and experiential sustainable building improves employee’s well being and increase productivity. This will move sustainability aspirations from a reductive performative notion; treating buildings as a mere optimized machine to look deeper into human experiences of housing experiences rather than housing functions. The corporate image seeks to find a surface treatments that reflect its commitment to its location and climate but also to offer an engaging urban and indoor sensory and experiential statement about its commitment to sustainability All case studies presented whether with an integrated renewable energy, moveable responsive facades or double skin are uneconomical solutions compared to traditional single skin configurations. These investments reflect a willingness to achieve a higher perception of sustainability and use it as means of engaging with the site and its environment. This paper doesn’t attempt to discuss how these facade technologies lead to real reductions in building carbon footprint as the original assessments using BREEAM were based on a shell and core principle which means that the building with its

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changing technologies and occupancies will naturally lead to variations in the targeted reductions from both passive and active measures. 5.

ACKNOWLEDGMENT

Personal thanks to Prof. Adam Sharr for valuable insights and comments on the arguments presented in this paper. 6.

REFERENCES

[1]

V.B. Canizaro, Regionalism, Place, Specificity, and Sustainable Design, in Pragmatic Sustainability: Theoretical and Practical Tools, S.S. Moore (Ed), Routledge (2010)150-167

[2]

D. Leatherbarrow and M.Mostafavi, Architecture, MIT (2002), 200-203

[3]

H.R. Hitchcock, P. Johnson, The international Style, New York (1932).

[4]

W. Gropius, The New Architecture and the Bauhaus, London (1935)p.18

[5]

Geidion, Architecture You and Me, Cambrige Mass (1958)

[6]

A. Simthson and P.Smithson, The Charged Void: Architecture, The Monacelli Press (2001)

[7]

C. Norberg-Schulz, Genius Loci, Towards a Phenomenology of Architecture, Rizzoli, New York (1980), 194-195

[8]

J. Pallasmaa, The eyes of the skin, John Wiley&sons (2005)

[9]

N.Hamza, Dudek S, Elkadi H, Impacts of changing face configurations on office building energy consumption, in proceedings of CLIMA 2000, Naples Italy (2001)

Surface

[10] N. Hamza and D. Greenwood, Hamza N, Greenwood D. Energy conservation regulations: Impacts on design and procurement of low energy buildings. Building and Environment 2009, 44(5), 929-936 [11] D. Leatherbarrow,Architecture’s unscripted performance, B.Kolarevic and A.Malkawi (Ed) in Performative Architecture, Spon Press (2005) [12] B. Evans, Solar Power Gets Serious, Architects’ journal, (1997) 205(24)pp44-45 [13] D.Jones, Architecture and the Environment, Bioclimatic Building Design, The Overlook Press (1998) [14] N. Hamza, Double versus single skin facades in hot arid areas. Energy and Buildings 2008, 40(3), 240248. [15] John Lewis Partnership, Sustainable construction Framework, (2007) available online-www. Johnlewispartnership.co.uk accessed 10/11/2010

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBN xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011 th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Designing for only energy: suboptimisation RONALD ROVERS 1

1

, KATLEEN DE FLANDER 1 LEO GOMMANS 1

WENDY BROERS

1

RiBuilT, Research Institute Built environment of Tomorrow, RiBuilT/Zuyd University, Heerlen, The Netherlands

ABSTRACT: Renewable energy is based on using a direct route from solar radiation to consumption, as an efficiency improvement from a long term route via fossil fuels. Both routes put a claim on space ie land and the time of use of that land/space to intercept and convert it to useful forms. With of course renewable energy routes far more effective as fossil routes. However, the same solar radiation is needed, to produce materials in a similar change from fossil materials to renewable materials, and the materials needed as well to produce the conversion devices for renewable energy. Similar processes take place in the realising sustainable buildings, especially 0-energy buildings: there is space time involved to generate the renewable energy, but also to generate for instance the renewable material based insulation materials, or the wooden construction. From research into exergy strategies, the starting points for such a building evaluation have been developed, and translated in a tool to evaluate buildings for their energy and mass performance together. A few first pilot buildings have been evaluated with this method, and show that in some cases its not energy reduction or efficiency that has the first preference, but materials input becomes the decisive parameter. Among other we find that insulation material from renewable sources like hemp or flax, face a maximum: there is a point where renewable energy input to heat the house is more environmentally effective then to add extra insulation. On a larger scale, for instance districts or neighbourhoods, the land involved to produce renewable energy , will compete with land needed for food and renewable materials production, which leads to other choices in design lay outs of buildings. In fact , to reach 0-energy (existing) districts in future, it could imply that life styles have to be changed, in the form of heating only part of the house in stead of the whole house to be able to provide a balanced resource use for materials and energy together, within the evaluated system. Several houses have been assessed this way, and the implications of the land needed are visualised to show the effects of energy and mass together. In fact this relates to the design and architecture of future buildings, but also to future landscapes: These will change adopting renewable energy devices, but at the same time become productive material landscapes. Partly this is already happening, with rapeseed, windturbines, PV solar fields, and production forests developing in countries in Western Europe, like Germany and Austria. The paper will address the evaluation of buildings for (renewable) energy and mass together, as well as the expected changes in architecture and landscaping. Keywords: 0-impact, exergy, embodied land, sustainable design, land use

1. INTRODUCTION A main focus today is on the CO2 emissions from our activities, and especially buildings. In some ways this is a strange approach, from different point of views. Firstly it’s a end of pipe approach,. We don’t solve the problem, we just continue and try to hide the negative impact, by storing CO2 emissions for instance. But especially for buildings this is a nonsense making approach, since we are already creating 0-energy buildings, and will only do so with the new EPBD regulation (EU) coming up. A (near) 0-energy building, which generates the total need of energy by renewable sources on site, [1] has no CO2 emissions anymore from operational energy. So why still bother about CO2 calculations? Of course there are other issues at stake. What about the embodied energy/ CO2 in construction for instance, and producing the energy conversion devices? In fact the to address the impacts from materials will become far more important then the

effects of operational energy.[2] Although there is hardly substantial attention for this. In this paper we will explore the consequences of this development, and explore the relation of energy and materials use in buildings , and the consequences if we try to establish a system of closing cycles for both. .

2. SOLAR RADIATION The use of Renewable energy is in fact based on using a more direct route from solar radiation to consumption, as an efficiency improvement from a long term route via fossil fuels ( which are renewable as well via biomass sedimentation routes) . In depth analyses shows that both routes put a claim on space/land and the time of use of that land/space to intercept and convert it to useful forms of energy. With of course so called “renewable energy” routes far more effective as “fossil routes”. : A exploring calculation shows that to produce oil all land on earth has been involved , over million of years, to produce

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

the current oil ( and gas and coal) stocks. A rough calculation learns that this is in the order of output of 14000 litre of oil per day globally ( which would be the balanced use of it) This implies a averaged production (of coal oil and gas) of 0,00173 kWe / hayear. (That is the resulting output from 1 ha via biomass-sediment-fossil fuel-electricity route) Compare this with Solar radiation via PV to electricity route: 1 million kWhe/ha-year This illustrates the relation with space and time for energy generation. ( So far the storage issue has not been addressed in this research. Further research will have to clarify how much land is involved with this) .

3. MATERIALS With a 0-energy building, the non renewable energy input is limited to the production of materials for the energy conversion devises, and the production of materials for construction: In both cases its materials that become the decisive parameters for environmental performance. And since materials itself become scarce as well in many fields [3], and require large amounts of ( so far) fossil energy to produce, a next step is to change for renewable materials, similar as for energy: This avoids huge energy consumption in the production of current materials ( and shift to mainly solar energy in the agro based production) and is, when balanced used, a way to avoid depletion of resources as well.. Of course in attempt to operate in a closed cycle the only option is to use renewable materials, non renewables by definition deplete. In a first exploration it has been investigated in how far reduction of materials, and change to renewable materials in buildings is possible. [4]. One of the calculated buildings was a 5-level new style canal house in Amsterdam, made of prefab

timberframe with straw bale filling/insulation, and other features.(ill 1) The house was from the start designed to perform for renewable materials, and ended up even 20 % cheaper as neighbouring houses of the same size. In this case the weight per m2 living area dropped to 550 kg, and the fraction of renewable materials was 43%. The next step is to try to bringing the renewable materials fraction to a 100 % percent, in that case a material neutral building would have been established.: a building that only uses renewable sources, imported from outside the building site This is similar to a energy neutral Building. However with 0-energy building the renewable resources are produced on site. Therefore, a 0-materials building should do so as well: (re-)generate the materials on site. This will require to identify a crop specific production rate , and calculate the amount of m2 to be incorporated in the building site to grow the resources. ( in fact, also in the neutral case and when imported, they still require land and time to develop and should be appointed for that) This leads to the notion that’s its no longer embodied energy as the interesting figure, but embodied land. Literally the ha-year calculation for generating energy and materials. This provides a new systematic approach to evaluate what’s the most interesting option to develop, or the option with the least embodied land , and make an integrated energy/mass evaluation possible. Since both develop from the same source: Solar radiation, and the space- time involved to generate. This however is not the same as a Footprint method: The Footprint methods calculates all impacts of human action into land needed to compensate this. Here is a more direct route chosen: If one works with closing cycles, side effects are hardly important anymore, and the direct land need to generate resources is calculated. done automatically when using the proper styles.

4. EMBODIED LAND

figure 1: Ijburg 3, a mainly renewable materials based house in Amsterdam, one of the calculated buildings

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The above described approach has been combined with studies into the exergy of buildings [5] , and leading to similar conclusions, that primary exergy is a principle based on fossil fuelled society, but that in the end Solar ( radiation) energy is the real originating reference, and as a result, the m2 land over a certain time as the parameter to measure. In a project at RiBuilt, the research institute for the Built environment of Tomorrow,. From research into exergy strategies, the starting points for such a building evaluation have been developed, including a draft database of yields per hectare, for most general crops ( according to local climate) and translated in a tool to evaluate buildings for their energy and mass. performance together. (ill 2) A few first pilot buildings have been evaluated with this method, and show that in some cases its not energy reduction or efficiency that has the first

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

preference, but materials input becomes the decisive parameter.

5. CASE IJBURG In the pilot we have calculated two cases, a Dutch average house, the formal defined governmental reference building , and the Ijburg-3 case, the canal house described before. For the purpose of this paper we will concentrate on Ijburg3 . The general approach is to calculate the embodied land for generating the materials, as well

5.1. Materials embodied land In the case of Ijburg , the production of (43% renewable) materials require 916 m2-year to produce , per m2 of living area. This can be produced in 1 year on 916 m2, or , if we take the lifecycle of a house as 50 years, on 18.3 m2 for the continuous period of 50 years. The space time occupation of embodied land significantly drops when lifetime of the house increases. There is still a fraction of non renewable materials involved. So far we have not defined embodied land for this fraction,. A follow up study has to explore this further, however only important as long as we still use some non-renewable sources, in the end, like renewable energy its not relevant anymore. 5.2. Energy embodied land

Figure 2 the methodology: schematic model of the calculations; the conversion to m2 land for crops, energy harvests, and water ( later to be added)

as the land required to generate the “embodied energy” in materials as well as the land for operational energy. We explored two cases: the use of fossil energy, and the 100 % change for renewable energy, also for production of materials. Ill model

To calculate the land involved in generating energy for production and transport the ICE database on Embodied energy was used [6] This has been recalculated for both fossil based energy and renewable based energy.(ill 4) To produce the energy for materials production by fossils, a land use of 43 million m2 per m2 of living area is involved ( on a 50 year regeneration basis…!) . A huge amount, of course. To do so with modern biomass energy generation 2,16 m2 is needed, and via PV panels 0,06 m2.( both in 50 years) ( only direct energy, not including yet indirect energy, for storage for instance) But it shows already the immense difference in effectivity whether fossils or renewables are used. For operational energy similar calculations are made: for Ijburg-3 0,08 m2 per m2 living area is needed. (solar generated, or 57 million m2 when fossils are used) From this point on its already clear that in the case of a change to renewable materials , with still using fossil fuels as energy source, the last one is by far the most devastating to our land use : A 100 million m2 for EE and OE per m2 living area, compared to 18.33 m2 for materials ( the 43%, maybe twice as much for a 100 pct renewable materials house) However, if we include the fact that we have to change for 100% renewable energy, the picture is completely turned upside down: 0,14 m2 for EE and OE compared to 18,33 m2 for the materials fraction ( on a 50 year calculation, but the relation remains the same) . This already shows that design decisions

Figure 3 Yields for different construction materials: the average yearly useful output per ha land. It shows that for instance wool and cork are a highly land consuming crop. Yields vary greatly in literature, and due to differences in location, climate, quality selection etc. . More research is needed.

Figure 4: the m2 calculation for different routes and functions

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

regarding materials have far more impact then those related to energy, in a renewable resources based world. As we will see later more in detail. A next step is to calculate for instance how many houses would fit in a new to develop district, including embodied land. Suppose we have one hectare of new housing area, if we develop this as a 0- energy neighbourhood, and as well as a 0materials neighbourhood, therefore including generation of all resources, we see that the ijburg 3 building ( 267 m2 total) requires nearly 5000 m2 of land, of which only two fit in a ha. For a more average house of a 100 m2 , its only a density of 5/heactare that should be allowed ( ( and still only 43% of materials are calculated as renewable) ( And both with a50 year lifetime. Of course density for other reasons could be increased, with enough land dedicated to the area to re-produce the resources.

5.3. Urban Harvest+ We used these findings in a second project, where we analysed if a existing district could produce its own resources, for the energy consumption as well as for new construction and maintenance. [7] Apart from the details, at a certain point it was obvious that we lacked land to install all energy devices as well as to produce additional renewable materials. This raise conflicts of interest as for instance with the energy calculation which started from the assumption that all house should be renovated up to passive house standards, reducing operational energy significantly. However, in this area of 6000 house s that would require a additional 135 hectares of materials production continuously, to produce the materials for renovation and maintenance. Another calculation was made in how far extra land was needed in case we did not insulate the existing hoses : to heat the houses that would require only 17 hectares of solar collector heat. Its obvious that that is far more effective, ie: the strategy should be not to insulate houses anymore. It would be sub optimising, and ineffective....

Of course, in a detailed analyses, it will show that somewhere there is an optimum between on insulating, a little insulation and passive standard, in terms of land use involved, for energy and materials together. [8] This has still to be more researched. But the general conclusion remains, only looking at energy in the classic way will bring us into problems. On a larger scale, for instance districts or regions, the land involved to produce renewable resources , will compete with land needed for food which will force even other optimisation decisions. All these needs transferred into time related land use, will change the current way of decision-making, and as a result landscaping, building design and city management.

6. DESIGN The broader approach of these findings are the notion that in the end its m2 available land that will decide what’s possible and what’s not: all resources, are related to solar radiation ( food, mass and energy) and our ability to convert the radiation into useful resources. Design on a small scale as well as on a large scale, will take into account the optimal use of m2, to make these productive. That counts for roofs, but also for land, gardens, roads etc, in order to maintain a high level of resource availability, once fossil fuels run out and some resources deplete or are to energy intensive to produce. In fact , to reach 0-energy (existing) districts in future, it could imply that reduction is not established by insulation but that life styles have to be changed, in the form of heating only part of the house in stead of the whole house to be able to provide a balanced resource use for materials and energy together, within the evaluated system.

6.1. Changes In fact these changes are already happening , though mostly unnoticed. What was free available

Figure 6 changes already visible in the landscaping

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

once, is becoming managed, planned and land(space) based. Take for instance fish farming: due to lack of fish, fish farming is fastly taking over “wild fish”. Including the ( managed and controlled ) land use( water surface) involved with this. Similar with FSC wood, or sugarcane crops for ethanol fuels in Brazilian cars. Not to speak about energy, rape seed fields, large wind turbine fields, solar panel fields arising around us. On roofs, but also taking virgin land ( which is not wise of course) . And this will continue to grow. In architecture we see similar changes . The shift for renewable materials has already had its take off. Since the fire risks were under control early this decade, the Scandinavian countries on a large scale construct multifamily houses in timber frame construction. Up to 9 levels has been realised, in Sweden and lastly London. Now a Austrian firm has launched the plans to construct a 20 floor apartment building to set the record. Plans for a 12 storey have already been licensed in Berlin. [9]

The first house had a ambition to be 0-energy and 25 % from renewable materials(ill 6) , the second design energy plus and 50% of renewable materials,(Ill 7) the third design, just selected this year, 75% renewable materials and the design for 2011 requires 100% renewable materials. Which will most probably fail, think of glass and hinges for instance, but students are challenged to go as far as possible. At the same time these resources have to be generated, which will be included in the demonstration area.

7. CONCLUSIONS In a world opting for 0-energy buildings, materials become by far the part of construction with the highest impact, whether fossil fuels or renewable energy is involved. In a complete change to renewable resources, both in energy as in materials, it’s the growing of materials itself which will be the main design parameter regarding environmental performance. The explorations made in the research underlying this paper, contain however still many issues to investigate, and to confirm findings with indepth and focussed research. But this does not conflict with the main conclusion that building design and landscapes will face a major change, with every m2 becoming productive, and the development of material landscapes around buildings as part of a 0-material building approach probably developing the coming years. The trend to develop 0energy buildings will show to be a suboptimal and ineffective way of approach, unless we re-interpreted this as 0-exergy buildings, in which energy and mass calculations are combined in a Embodied land approach .

Figures 7 and 8 First house under construction: a passive house, and design for the second building, with productive roof

In the District of Tomorrow, a demonstration project , these changes are a leading ambition: Students are mandatory to design a highly ambitious plan for their graduation, with performance criteria in energy water and materials for instance. The best design is selected by a jury and constructed a year later in the demonstration site in Heerlen, Construction by the way is by students of construction schools, as a training environment.

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8. REFERENCES [1] Rovers, R., Rovers V., 2008 0-energy or Carbon neutral? Systems and Definitions, Discussion paper, not publishes, see www.sustainablebuilding.info [2] Sartori I. , et all , 2006, Energy use in the life cycle of conventional and low-energy buildings:Department of Architectural Design, History and Technology, Norwegian University of Science and Technology (NTNU), Trondheim, Norway [3] EU natural resources 2005 [4] Rovers,R. 2009, Material-neutral building: Closed Cycle Accounting for building Construction, paper SASBE conference, Delft, The Netherlands 2009 [5] SREX : Long term research program financed by Dutch Government, exploring the exergyprinciple for Spatial planning. Universities of Groningen, Delft , Wageningen and Heerlen, reports.http://www.exergieplanning.nl/ [6] ICE database, Inventory of Carbon and Energy, version 1.6a, prof G.Hammond and Craig Jones, Bath University, Availanle from: www.bath.ac.uk/mech-eng/sert/embodied/ [7] Urban Harvest +, case Kerkrade West, a exploration into 0-impact district re-development, 2010, RiBuilT Research institute Built Environment of Tomorrow, Heerlem NL, download at: www.ribuilt.eu [8] Gommans, L. J. J. H. M. (2009). "The use of material, space and energy from an exergetic perspective." Proceedings Sasbe 2009 Conference on Smart and Sustainable Built Environments. [9] Rhomberg H. 2010, A life cycle tower for a better future. In book: Towards 0-impact buildings and built environments, Technepress NL, edited by R.Rovers.isbn 978-90-8594-028-9

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Multidisciplinary Master Zero Energy Building Design Project based on Workshops for Professionals Wim ZEILER Technische Universiteit Eindhoven, Eindhoven, Netherlands ABSTRACT: Building industrial practice a design approach is increasingly being asked besides specialist engineering skills. This leads to new demands for the educational programmes to prepare the engineering student for these new demands. One initiative in our University is the so called multidisciplinary master project ‘Integral Design’. In this project architectural students and engineering students participated. As basis for this project served a learning-by-doing workshop approach, developed and tested with/on experienced professionals in series of two days learning-by-practice workshops which was developed and tested in practice with collaboration of Institute of Dutch Architects (BNA) and the Dutch Association of Consulting Engineers (NL Ingenieurs). This is one of the few educational projects in which the experience from practice is transferred directly into the educational academic program; normally this is done the other way around. Quite remarkable is that these workshops by themselves became part of the permanent professional educational program of the BNA. The results of a comparison between the multidisciplinary master project and the experiences of the professional are discussed. Keywords: workshop, professionals, students

1. INTRODUCTION The product which has the biggest impact on sustainability of humans are their buildings. The built environment uses 40% of all our energy for conditioning the buildings and 8 % of all our energy to be built. Building designs need to provide solutions for sustainability issues ranging from flexible use of renewable energy, energy reduction measures while maintaining and even increasing comfort level of the users. Sustainability is a crucial issue for our future and architecture has an important role to direct sustainable development [1].However there is a mixed performance in the realization of sustainability objectives, there are a number of key barriers hindering progress and as a result the process became more complex [2]. As complexity of design processes of buildings increase, traditional approaches may no longer suffice [3]. New approaches are needed to bridge the gap between ‘Art (Design)’ and ‘Science (Engineering)’ worlds, in case of the building design specifically between architects and consulting engineers (structural, building physics and building services). Education has a vital role to play in developing sustainable development: Development which meets the needs of the present without compromising the ability of future generations to meet their own needs [4] This led to the development of Zero Emission Buildings: a building which emits virtually ‘0 (zero)’ carbon dioxide [5]. However this new target in building design, ZEB, requires totally different approach from conventional building in terms of design, construction and operation [5, 6]. That goal is very ambitious for the moment [7] and can only be realized by applying renewable energy source and

an extreme low energy use of the building. Such complex design tasks requires early collaboration of all design disciplines involved in the conceptual building design. Architects and engineers need to be able to handle the challenges imposed by the new design goals. Models are needed to bridge the gap between the worlds of Design Methodology and Reflective Practice, and to look at designing as a process in which the concepts of function, behaviour and shape of artefacts play a central role [8]. This can eventually lead to an integral process, team and method [9]. Design education needs to help engineering students and architectural students to develop the necessary skills to successfully handle design tasks [10] and so give them the knowledge and ability to realise this aim is the main intention of the multidisciplinary masters’ project ‘Integral design’. To test our ideas for a new educational approach experiments were done in a situation as close to design practice as possible: in workshops for professionals [11]. Education should prepare students to become professionals therefore it is of importance to look into the appreciation of the proposed design tool within building design practice. The professional workshop formula was used to start the students’ master project integral design team work. The methodology, the used design method and its main tool, the morphological overview, are described in section 2. Section 3, describes the workshops for architects and engineers. Our Master project Integral design uses the same concept as a start-up for the project. In section 4 the results are given of the different questionnaires that were held to gain insight in the appreciation of different aspects of the design tool used in the workshops. Especially a comparison is made between the results of

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professionals and those of the students. After a short discussion in section 5 conclusions are given about whether or not both students and professionals think the integral design method is useful for them.

2. METHODOLOGY Integral Design [12] was chosen as a starting point of development. Based on methodical design a well known design method in the Netherlands [13], Integral Design is a design process model; the cycle (define/analyze, generate/synthesize, evaluate/select, implement/shape) forms the sequence of design activities that take place [14].

Figure 1: Four-step pattern of Integral Design A distinguishing feature of Integral Design is the intensive use of morphological charts for design steps in the design process [15,16]. In the first step the designer list his interpretation of the most important aspects and functions that have to be fulfilled based on the design brief in the first column in the chart. In the second step of the process the designers adds possible part solutions to each aspect or function in the rows after the specific function or aspect, see Fig. 2.

Figure 2: Morphological charts as part of the Integral Design method, step 1 and step 2. Each participant of a design team develops a morphological chart from their own specialist point of view. These individual discipline based morphological charts can be combined to one overall so called morphological overview. The morphological overview of an integral design team process is generated, by combining in two steps the different morphological charts made by each discipline. Putting the morphological charts together enables to ‘put on the table’ the individual perspectives from each discipline about the interpretation of the design brief and its implications for each discipline. This enables, supports and stimulates the discussion on and the selection of functions and aspects of importance for the specific design. In step one the functions and aspects are discussed and decides with are placed by the team in the morphological overview. After this in step 2 all participants of the design team can come up with their solutions for these functions and aspects, see Fig. 1 & 2.

Figure 3: Two steps to come from the morphological charts to the morphological overview: step 1

Figure 4: Step 2 to come from the morphological charts to the morphological overview. It is important to divide the process leading to the morphological overview into two steps to structure the discussion between the different disciplines about the most important functions and aspect in relation to the design brief. After the important first step the solutions by all the different disciplines can be added. The result is a transparent and clear overview of the interpretation of the design brief by

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the design team as well as an overview of the known possible sub solution by the members of the design team.

3. EXPERIMENTS Since 2005 we organized 5 series of workshops with professionals, architects and engineers, voluntarily applying to participate [15,16]. The integral design method with its use of morphological charts and morphological overviews was tested in these series of workshops organized in cooperation with BNA (Dutch Royal Society of Architects) and NL Ingenieurs (Dutch Association of Consulting Engineers). The only selection criterion used for selecting the participants is the requirement to be a member of either BNA or NLIngenieurs. The participants are randomly assigned to design teams, which ideally would consist out of an architect, a building physics consultant, a building services consultant and a structural engineer. The experiences of workshops series led to step by step adjustments resulting in a final setup workshop which was used in series 4 and 5 [15], see Fig. 4.

Figure 5: Session of workshops series 4 & 5, four design sessions with different set ups of participants and use of Morphological Charts (MC) or Morphologic Overviews (MO) in two days During two days there are four different design sessions during which the team has to perform a specific design task. The design tasks during these two days are on the same level of complexity and have been used in all workshops. After each design session the participants present the results to each other and get feedback from the organizers. The participants are rearranged after each design session so that no one works together with someone else more than once, this to avoid a learning effect in the teams during the different design session. The workshops start with a lecture introducing Integral Design and are followed with other supportive lectures about sustainable energy systems, the use of morphological overviews and overall feedback of the results to all participants. The workshops typically include around twenty participants. In this final configuration of the workshop series (Fig. 5) stepwise changes to the traditional building

design process, in which the architects starts the process and the other designer join in later in the process, are introduced in the design sessions. Starting with the traditional sequential approach during the first design session on day 1, this provides the participants a kind of reference experience so in session 2 they can get the understanding how the process changes by letting all disciplines start working simultaneously from the very beginning of the conceptual design phase. After the first day the application of the integral design model / morphological overview is introduced during the third design session to demonstrate to the participants the effect of using morphological overview: transparent structuring of design functions/aspects on the amount of generated (sub) solution proposals. At the end of the third session the participants receive feedback about their applying the morphological charts and morphological overview. The third session provides one full learning cycle regarding the use of morphological overviews. After this third learning session the participants can apply the morphological in the intended way. So in design session 4 the design teams really can experience the effect of the integral design method and its tools, morphological charts and morphological overview. During the second day of the design workshops the sessions allows simultaneous involvement of all design disciplines on a design task, aiming to influence the amount of considered design functions/aspects by giving the teams tools of Integral Design; morphological chart and morphological overview.

1st design session, parasite pavilion as an example for sustainable building as design task In design session 1 each architect was given the task to design a ‘parasite’ structure to be placed on the building the workshop was taking place in. For full description of the design task see [13]. Initially, in the first design session, which lasted approximately 30 minutes, the architect worked alone on the design. After the initial part of design session I, the other team members met in the second part of the design session, to discuss the design and work together further on it. 2nd design session, energy neutral office as design task The task was to design an energy neutral office. All participants started together at the same moment with the design process but in mono disciplinary groups. After this first part of the design session 2 the participants were divided into new multi nd disciplinary teams. In this 2 part of design session 2 all participants started together with the same nd information about the project in contrast with the 2 part of design session 2. First, representatives of the individual disciplines explained the results of their

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st

work from the mono-disciplinary team in the 1 part of design session 2. After these individual explanations, team discussion ensued. The focus of this discussion was on fitting sub solutions into a final design.

th

3 design session, renovation zero energy roof apartments as design task The task was to design a zero energy apartments on the top floor of the building (roof). The participants were given an introduction on Integral Design and an explanation on how to use the tools of Integral Design, the morphological chart and the morphological overview. The design teams started as multidisciplinary teams working with the morphological charts and morphological overview. Design session 3 represented a learning-by-doing opportunity for the individual disciplines and the design teams. The ideal outcome would be that each team could clearly demonstrate successful use of the design tools during the design process. However, as a key part of learning is feedback, after the teams completed tasks set in session 3, time was given to compare and appraise the teams’ work and to answer any questions that arose [13]. th 4 design session, energy neutral school as design task The task was to design a school with healthy and sustainable environment for children. The same location and overall demands as for ‘zero energy office’ design task was used. Design session 4 represents the very last stage in the cycle of research in this research project. All of the individual interventions that were used in the earlier research stages are combined so that in session 4 the IDmethod can be tested. To be explicit, the elements that have been combined are: design team, design model, design tool and design session.

have all disciplines represented in each team. This makes it possible to compare the student workshops with the results from the workshops for professionals. 1st design session, parasite pavilion sustainable building as design task In order to demonstrate what occurred in design session 1, the work and analysis of one team is presented below, while the work of the other teams can be found in [15]. After the initial part of design session I, in which the architect worked alone, all team members met in part 2 of the design session, to discuss the design. Here, the architect led the discussion. The analysis of each team’s work started with the translation of the architect’s explanation of the initial proposal at the beginning of second design session is into a table of aspects and sub solutions, see table 1. This resulting sequential list is then structured in the architect’s morphological chart. Then, on the basis of a review of the videotaped session, a table of aspects and sub solutions considered by the design team is structured in the design team’s morphological overview. The analytically derived morphological overview of team 1 from the explanation of the architect to the other team members, is presented in Fig. 6. The aspects/functions and sub solutions originally brought to the table by the architect can be found as {A} in Fig. 7. After the discussion with the designer of other disciplines the team decided to work on those aspects and functions were they all agreed on leading to the morphological overview of Fig. 7, which represents the final result of the first design session. Through the discussion and selection of aspects and functions as well as the related subsolutions, the team members manage the consistency of the solutions. Inconsistent subsolutions are either improved to become consistent or left out. Table 1. Transcript of functions/aspects and subsolutions mentioned by the architect.

4. RESULTS Interaction between practice, research and education forms the core of our integral design approach. Therefore we implemented the integral design workshop for professional’s set up within the start-up workshop of our multidisciplinary master project integral design. Students from architecture, building physics, building services, building technology and structural engineering were offered the opportunity to participate. Because of the intensive coaching not more than six teams were formed. The procedure for the start-up workshop for the student’s project was the same as for the professional workshops; the only criterion for participation was the ‘membership’ of the ‘master students group’. The students of each discipline were randomly assigned to design teams, with the aim to

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Figure 6: Architect’s morphological chart, design session 1, part 1.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 7: Design team’s morphological overview, design session 1, part 2 nd

2 design session, energy neutral office as design task The analysis of the second design sessions of the second workshop design session is based on videotaped design team activities. The resulting table of aspects and sub solutions considered by design teams during session II is structured into the design team’s morphological overview. 3th design session, renovation roof apartments as design task Design session 3 represented a learning-bydoing opportunity to work with the specific design tools for the individual disciplines and the design teams. The ideal outcome would be that each team could clearly demonstrate successful use of the design tools during the design process. However, as a key part of learning is feedback, after the teams completed tasks set in session 3, time was given to compare and appraise the teams’ work and to answer any questions that arose. 4th design session, energy neutral school as design task Design session 4 represents the very last stage in the cycle. All of the individual interventions that were used in the earlier research stages are combined so that in session 4 the ID-method could be tested. To be explicit, the elements that have been combined are: design team, design model, design tool and design session. In this session, all of the design teams’ proposed sub solutions were recorded directly on morphological overviews. The results of the workshops in their final form held for professionals and students are compared. In the compared final two workshops series 38 professionals participated, average age 42 and on average 12 years of design practice experience. In the two parallel workshops for students 42 participated, average age 23 and no design experience from practice. Direct at the end of the workshops the participants were asked to fill in a questionnaire about the use of morphological overviews during the design sessions and about the concept of the workshops themselves. The results of the comparison are given in Fig. 8 and 9 on a scale from 1 to 10. The results of the questionnaires indicate that the participants thought the use of morphological overviews increases the insight in other disciplines,

helps the communication and increases the number of relevant alternatives within the design process. Surprisingly there is a rather small relative difference between the appreciations of professionals as compared to that of students see Fig.9.

Figure 8: Comparison results questionnaires the later series workshop of two days for professionals and students, rating on a scale from 1-10. Based on the workshop a more compact for of the workshops was developed and introduced in the Master project Integral design for students from architecture, building technology, structural design, building physics and building services. Instead of 4 design session within two day the workshops were reduced to one afternoon session on day 1 and one morning session on day 2. On day 1 the students had to perform the design task 1 of the former workshops in teams of two and design task 2 of the former workshops series in team of 4 students. In the teams were always different disciplines combined. After this during the morning of the second day they had to perform design task 3 together with one professional expert in each group. This made it possible to connect professional experience with the approaches by the students. After session 3 the participants were asked to fill in a questionnaire which made it possible to compare the outcome of students and professionals, see Fig. 9.

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Figure 9: Results comparison professionals – students 2011

5. DISCUSSION AND CONCLUSION In this paper we discussed the connection between building industry and university by multidisciplinary workshops for professional (architects and engineers). Traditionally a design method is developed at a university where it is tested on students and then implemented in practice. In our case we choose to change this; the testing was done as near to practice as possible with professionals and then implemented at the university. The result was that, were normally the evaluation of the design method and its tools by practitioners lead to a lower appreciation than that by students; in this case the situation was reverse. The practitioners thought the design method and its tool of more value than the students. So we presume that by using our integral design workshops with the use of morphological overviews, we prepare our students well for the practice with its multi-disciplinary design problems they have to face when designing zero energy buildings.

6. ACKNOWLEDGEMENTS This research was done with the help of the Royal Institute of Dutch Architects (BNA) and the Dutch Association of Consulting Engineers (NL Engineers). The Foundation for promoting Building Services (PIT), supported the research financial.

7. REFERENCES [1] Taleghani , M., Ansari, H.R., Jennings, P. 2010, Renewable energy education for architects: lessons from developed and developing countries, International Journal of Sustainable Energy, vol.29, No.2, June 2010:105-115

[2] Williams, K., Dair, C. 2007, What is stopping sustainable Building in England? Barriers experienced by stakeholders in delivering sustainable developments, Sustainable Development, Vol.15, Issue 3, May/June 2007:135-147 [3] Aken J.E. van, 2005, Valid knowledge for professional design of large and complex design processes, Design Studies, 26(4), pp 379-404. [4] WCED, 1987, Our Common Future, World Commission on Environment and Development, Oxford University Press, Oxford. [5] Kang H.J., Lee S., Rhee E.K., 2010, A Study on the Design Process of Zero Emission Building, Proceedings Clima 2010-10th REHVA World Congress, 9-12 May, Antalya, Turkey [6] Ritter V., Assessment of the guidelines for zeroemission architectural design, Proceedings Clima 2010-10th REHVA World Congress, 9-12 May, Antalya, Turkey [7] Opstelten I.J., Bakker E.J., Sinke W.C., de Bruijn F.A., Borsboom W.A., Krosse L., 2007, Potentials for energy efficiency and renewable energy sources in the Netherlands, WSED2007 – Energy Future 2030, Wels. [8] Vermaas P.E., Dorst K., 2007, On the conceptual framework of John Gero’s FBSmodel and the prescriptive aims of design methodology, Design studies, 8(2), 133-157 [9] Seppänen O., Steenberghe T. van & Suur-Uski T., 2007, (editors), Energy Efficiency in Focus – REHVA workshops at Clima 2007, REHVA Report No.2. [10] Adems R.S, Turns J. & Atman C., 2003, Educating effective engineering designers: the role of reflective practice, Design Studies 24 (2003) 275-294. [11] Savanovic P., Zeiler W., 2007, Integral Building Design Workshops: A concept to structure communication, 4th DEC symposium, Las Vegas, DETC2007-34377 [12] Zeiler W., Savanovic P., Quanjel E., 2008, Integral Conceptual Building Design Workshops, Proceedings TMCE2008, April 21-25, Izmir [13] Blessing L.T.M., 1994, A process-based approach to computer supported engineering design, PhD thesis Universiteit Twente. [14] Zeiler W., Savanovi P., 2009, General Systems Theory based Integral Design Method, Proceedings ICED’09, 24-27 August, Stanford, USA [15] Savanovi P., 2009, Integral design method in the context of sustainable building design, PhD thesis, Technische Universiteit Eindhoven [16] Zeiler W., Savanovi P., 2009, Reflection in building design action: morphology, Proceedings ICED’09, 24-27 August, Stanford, USA

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Sustainable Environmental Design Consultancy: Practices informed and Practical outcomes. Michael SMITH-MASIS, Jorge RODRIGUEZ, Maria MENA-DEFERME 1

SAA International

ABSTRACT: SAAI is an international sustainable environmental consultancy firm with offices in U.K., Greece, Mexico, Costa Rica, Thailand, China, Spain and Australia, focused on sustainable architectural design research. This paper aims to present a series of practical outcomes obtained from experience of working with local practices in four continents as a guide to inform design decisions. Keywords: sustainable design, consultancy, design strategies.

1. INTRODUCTION The past economic crisis revealed clear opportunities in the direction of a revitalized global sustainable design agenda. The construction industry was deeply affected, and clearly projects were on hold or even stopped, and only a few stayed on course, but with solid economic arguments that in many cases, sustainability was an important part of its consistency. In fact energy consumption, carbon emissions and comfort assessments were targeted into a profitable way. Conversely in the past decades we exceed our planet bio-capacity in 35% and buildings deeply affected this figures, e.g. 50% of UK’s energy consumption is accounted to artificially conditioned buildings. Even in countries where energy comes from renewable resources (e.g. hydro plants), buildings are designed to operate artificially; leading to poor energy consumption routines and weak interpretations upon life quality and comfortable conditions. Thus the industry and real state markets started to look upon sustainability as a perfect complement to develop just the “appropriate product”. According to the U.S. Green Building Council new studies and reports point to green building as one of the growing bright spots for the U.S. economy. Economic experts call for a recovery plan focused on green jobs and infrastructure, as consumers developed a sense of economical awareness to live in sustainable environments, as businesses strive to cut operating costs. The US so called “Green buildings” aimed to strongly incorporate renewable energy resources against pressing challenges to change the way we view the building industry [5]. The sustainable design paradigm changed from being a misconception of an added value, towards being an intrinsic part of every design act and living. As “green buildings” help companies cut costs and buildings solved financial situations, the Center for American Progress’ [September 2008] study, shows how such green investments on a wide scale can ignite the economy a nation as a whole [5]. Among other aspects, SAAi merges from this particular scenario as a Global outsourcing

consultancy firm, seeking to complement and enhance architectural qualities of design practices. However sustainability is by far, a complex and ample concept aiming for equilibrium from which architecture can contribute into very specific manners. Depending on the project’s complexity, an specific multi disciplinary team is assembled in order to face each task according to its individual need, complementing in this way the architectural area with energy specialist, acoustics engineers, environmental engineers and any other professional necessary to full fill the project objectives from the conceptual and design stage, up to the construction phase. This paper aims to present a set of design recommendations and outcomes resulting from worked examples developed with local practices in four continents. First the work methodology and design brief will be introduced, followed with common analytical tasks and practical outcomes achieved during the various processes to inform early design decisions. Ultimately the outcomes will illustrate recommendations in terms of design ratios, base case to parametric studies, diagramming to visualize performance, the implementation of analytical tools to virtual models, empirical data to environmental measurements, not to simulate reality but to encourage pre-design studies informed with fundamental design criteria. Finally the most relevant part comes along from the process of applying theoretical concepts into practical skills for any given multidisciplinary team.

2. LINKING SUSTAINABILITY MULTIDISCIPLINARY

AND

Sustainable design has taken over. In the last years, a great deal of architectural practices has strived to improve the environmental response of their designs. Whether market driven or truly committed, it certainly aroused an interest in the establishment of new collaboration frameworks with other disciplines. On the other hand, the overregulated context has undermined the role of the architect to some extent. The romantic idea of inspiration and talent as driving agents of the design

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process often collide with statutory complexity and technical limitations. This led to a paradoxical situation where technical consultants are seen as the needed evils. However, new targets bring new opportunities. Architects aiming to deliver sustainable designs are open to the inputs from experienced advisors. Sustainability is a new communication channel and a common ground from which better collaboration could be built up. It is therefore necessary to establish this new collaboration framework in order to maximize the potential of a multidisciplinary approach towards the achievement of better and more sustainable environments.

3. EMPHASIS AND DESIGN LAYERS

Figure 1: Layers of appropriate design

Identifying particular issues for each project is critical to inform early design decisions, however a common working frame is necessary to ultimately personalize each project. The premise is to minimize energy demand and if there is any high demand, it has to be confronted by using alternative and renewable energies. Finally if energetic needs are outstanding, the most efficient systems must be incorporated. However, the later usually leads to a poor notion of “green design” or even “green wash”, when latest “technological trends” are defined as the main driven forces; more like an image rather than truly environmental sustainable design. Therefore the “green” project merges from the latest renewable energy trends (e.g. PV, wind turbines), “intelligent” buildings, high technological louvers, green roofs, among others; which from the first place could be highly questionable or even avoided if a clear understanding of the project’s context, typology, form and materiality is considered. A scheme for any project needs to strive a series of chronological considerations or design layers; starting from simple principles up to assessing complexity gradually; informed upon particular design requirements. The first consideration is climate and site understanding. Then form, typology and orientation to articulate fundamental bioclimatic design criteria within onsite observations. In most projects both initial layers can clearly indentify and resolve environmental problems. Then facades and materials should be considered to complement solutions in

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terms of form and materiality. Ultimately if there are any outstanding problems left, technologies and systems maybe a feasible option as for any specific control strategy. It is important to say that after covering each layer, the process become iterative. Figure 1 illustrates such working scheme.

4. WORK

METHODOLOGY DESIGN BRIEF

TOWARDS

A

Embarking on any sustainable environmental consultancy process requires a cumulative methodology, building up information along the process. Obtained experience from several projects points out the necessity to identify at least 4 chronological working stages; Must, Basic, Broad, and Specialized. Each one evolves to acquire greater depth and complexity. Every phase is a requirement to the one that follows. Each analytical phase aims to establish and inform design decisions in terms of the overall building performance; hence simulations, diagnosis, design principles and recommendations are assessed. “Must” Phase is related to site and climate analysis, microclimate patterns, field studies, empirical data and environmental measurements. All the studies are comprised with diagnosis diagrams based on hourly climatic data, building typology studies, and the definition of relevant design parameters to evaluate comfort and performance. This stage is prerequisite to all others, and perhaps is the most important because defines the practice basis. “Basic” pursues to inform early design decisions with diagrammatic recommendations and practical opportunities upon fundamental bioclimatic design criteria. A diagnose is given within floor plans, sections and facades of the predetermined idea. “Broad” works as an extended performance evaluation and “Specialized” amplifies details and develops parametric studies, hence assessing building performance, visual and thermal comfort, and solar geometry among others. A wide variety of digital tools are used to simulate environmental conditions. Finally Post design services are offered to support technical execution, onsite inspections, post occupancy evaluations and certification processes requirements. Identifying particular issues for each project is critical to inform early design decisions, however a common working frame is necessary.  

5. PRE-DESIGN:

ANALYTICAL TASKS INFORM EARLY DESIGN DECISIONS.

TO

Pre-design refers to determine environmental features and parameters that can be studied to achieve a desirable performance. The first approach is to establish comfort targets and building requirements for the design brief. Then a morphological synthesis of the project starts taking shape from cero or even if the design has already been started. The model synthesis is informed from environmental parameters to be studied with physical, analytical or numerical tools. Base case to parametric studies. The main idea is to work upon spatial graphs, which can illustrate the dimension of the problem and

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

requirements. Thus a simplified version of the project comes along, usually related to generic forms or primitive solids to evaluate performance and verify fundamental design criteria. Starting from there, a base case is determined and grows in detail and complexity by adding information and parameters to give an approximation to the final outcome.

compared with ISO comfort standards such as PPD or PMV. Additionally visual angles, build and natural elements are documented and ultimately comprised in diagrams that illustrate findings (figure 5).

Figure 3: Isla Verde Hotel; base case definition

Figure 2: Isla Verde Hotel; performance targets and requirements. For Rodrigo Carazo Arquitectos San Jose, Costa Rica.

Figures 2,3,4 illustrates this process for a hotel project in San Jose, Costa Rica, which intended a naturally ventilated atrium within an urban context. First performance targets and building type requirements were integrated with architecturalgraphical interpretations of the space. The base case looked upon design principles to capture prevailing winds and optimize ventilation during occupational patters. Several scenarios were studied and gradually ventilation performance was enhanced without active means. Conversely the process started from revising AC requirements that over dimensioned the problem. At the end a mixed mode was designed and AC cost reduced up to 50% with a clear definition of comfort, responsiveness and adaptive behaviours contained by a healthy environment. Empirical environmental measurements Every project needs to starts from a clearly understanding of the context, climate and microclimatic particularities. Even though hourly data gathered from meteorological stations is reliable, a deeper interpretation of the site has to be taken into account with onsite observations and empirical measurements. Despite the fact of just having a few samples as contrast to year-hour information, such measurements amplify a deeper ‘sense of place’, hence to understand microclimatic phenomena or distinctive behavioural patterns of the environment. At this juncture the main objective is to collect and observe environmental data for further analysis. For every site, representative points are selected to measure wind speed & direction, DBT, relative humidity and surface temperatures among others. For diagnosis purposes, each sample is

Figure 4: Isla Verde Hotel; Atrium CFD parametric studies. For Rodrigo Carazo Arquitectos San Jose, Costa Rica.

Visualization: Environmental diagrams and performance Diagrams play a key role to communicate findings in multidisciplinary work. They become vehicles to comprise criteria into architectural notion of space for any given qualitative and quantitative research. Recent software developments has proven this fact, thus powerful platforms aim to link performance parameters with outstanding 3D visualization outputs; rather than relying just on numerical tables.

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Figure 7: Isla Verde Hotel; Atrium Daylight Rules of thumb. For Rodrigo Carazo Arquitectos San Jose, Costa Rica. Figure 5: Capris Warehouse; Field measurements and comfort assessments. For FCB architects San Jose, Costa Rica.

Architectural environmental diagrams are powerful tools, which generate visualization triggers; hence a clearly understanding of the spatial notion phenomenon. In practice it is recommended to consider diagrams which: -Identify distinctive architectural characteristic of the space and are kept as consistent references for every analysis. -Correlate environmental data with a sense of space, temporality and occupational patters. -Useful diagrams are always synchronized with basic design guidelines such as ‘rules of thumb’. -It is recommended to define the same graphical code for all documents. Line types and chromatic scales are important to present information and emphasize particular situations.

 

Figure 8: Isla Verde Hotel; Atrium Aperture: Façade recommended ratios. For Rodrigo Carazo Arquitectos San Jose, Costa Rica.

 

-3D visualisations have proven a clearer understanding of the project rather than typical 2D sections. In fact, identifying the appropriate 3D section of the space has to be a consistent argument for any profound environmental analysis. Once selected overlapping output layers may enhance this Approach. Assessments & fundamental design criteria At the end, recent experience has proven that the best way to translate final results for an easy understanding of the multidisciplinary team has to be given as a set of rules of thumb. A sense of proportion needs to be graphically explained to inform design decisions. Thus ratios are worked again as diagrammatic examples; giving recommendations and design parameters to manipulate the building’s envelope, plan, form and materiality. Into some extend all recommendations are based on relevant literature, personal experience and the revision of best possible practice.

6. COMMON

RESEARCH BIOCLIMATIC APPROACH

 

Figure 6: Capris Warehouse; Project environmental synthesis. For FCB architects San Jose, Costa Rica.

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TOPICS

A

Each project has its own research agenda but some topics are consistently present throughout. A systematic methodology can help to accumulate precedents and extrapolate findings from a project to the next one. Merging empirical experience and

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

theoretical knowledge is the vehicle to predict environmental performance of each design with rigour and precision. -Ventilation. The first thing to determine when addressing ventilation is to define its role in the project. To avoid confusion, ventilation studies are initially divided in three sections: air quality, ventilative cooling and comfort cooling. Depending on the climate and building function, the demand for each type of ventilation will differ and the design response will be a compromise among these three approaches and energy efficiency. After initial studies, the research can go deeper on specific agendas. In recent projects, the existing dichotomy between open and closed spaces was explored. Strategies for hermetic and permeable schemes were foreseen under an interiorexterior function. In these cases, the building’s skin played a fundamental role to obtaining comfortable conditions. -­‐Solar geometry and shading. It has been noticed that this is a field were designers feel more comfortable and the interaction with the environmental advisor is more fruitful. The close cause-effect relation and the opportunity to undertake empirical observations facilitate communication. Solar geometry studies starts already with the climate analysis, but it is not just confined to latitude and orientation. The study of the context is the second step to get finally to the specific building layout. According to our transnational experience, architects who work in the tropics are normally conscious about the importance of solar control whereas in temperate regions this awareness is very little. When solar geometry is analyzed from the outset of the project, it becomes a useful an inspiring force. A recent project consisted on a consultancy for a competition for an office building in Spain. A different opening configuration was devised for each façade in order avoid overheating in warm periods while maximizing solar gains and minimizing heat losses during the rest of the year. This simple statement was followed throughout the design process. The final result was building with a character on its own which was awarded with the second prize on that competition.

 

-Daylight. It is understood that daylight is one of the most valuable assets on architectural design. In this multidisciplinary collaboration framework, daylight is addressed from two different perspectives; quantity and quality. Daylight quantity refers to the minimum levels to carry out the typical tasks within the space (as diverse as reading, painting, or walking) comfortably. The aim is to provide enough natural light for as long as possible without disturbance from glare or other undesired effects. The preliminary information for the design team comes in the form of graphic material showing effective window to floor ratios, potential window distribution and window height to depth proportions. Further analysis will evaluate daylight performance in proposed spaces and if necessary improvement proposals are put on the table. Daylight quality is not about statutory requirements but space and perception. Studies start with the setting out of the architectural intentions; sketching the intended effect with the architects could do this. In principle, daylight quality is subjective and unquantifiable. However there are lessons about materials, proportions and sources of light that can extract from built precedents. Findings from built precedents are translated to the current project by means of computer tools and physical models which are then exposed to the heliodon. Hands on methods and the use of tools, which are closer to the architect, facilitate cooperation.

7. ENVIRONMENTAL

DESIGN TOOLS: ANALYTICAL TO VIRTUAL MODELS

Analytic tools have a double function. On the one hand, they allow systematization of the calculation and evaluation processes. Complex analysis can be performed instantaneously and results are reliable when the inputs are correct. On the other hand they serve as communication catalyst between architects and environmental consultants. Paradoxically, although it seems obvious that an analytic tool is primarily intended to perform analysis, the second function outweighs the former in many cases, mainly in simple projects where past experience can be extrapolated and simulations and virtual models are only needed to confirm and illustrate expected tendencies and patterns. Only in the most innovative projects there is some margin for unpredictability. In all the others, the analysis is orientated towards a clear target, and the answers to the found are to confirm an initial hypothesis. Good calibrations as well as a good understanding of the processes and mathematics and behind the software are essential to get reliable and accurate results. Rigour and experience are then fundamental to interpret and process those results.

Figure 9: Campo DaFeira; Solar Geometry & Shading studies. For Carmen Mazaira Architetcs Partovia, Spain.

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a cumulative working frame, which builds up the project in ‘knowledge’. It is critical to clarify this with clients so the appropriate process starts and builds upon solid basis.

9. ACKNOWLEDGEMENTS We will like to acknowledge all Saai Associates and collaborators from around the globe. Especially to Costa Rica: MA. Juan Carlos Sanabria, Arch. Esteban Zamora and Arch.Laura Morelli, Thailand: Ekachai Sophornudornporn. Greece: Mania Abatzi and Leonidas Beis. China & Australia: Raymond Li. We will also like to acknowledge ITESM Campus Leon (Mexico) and Universidad VERITAS (Costa Rica) for their support along the process.

10. REFERENCES

Figure 10: Isla Verde Hotel; Atrium daylight studies per space. For Rodrigo Carazo Arquitectos San Jose, Costa Rica.

8. CONCLUSIONS FROM THE PROCESS AND PRACTICAL OUTCOMES

Specific threats and opportunities have been identified from the accumulated experience in different projects and working with different design teams around the world: -Technical support in environmental design is needed from the very early stage of the process. The most efficient contribution to design development is given during the design concept stage. In this way, the project can be fashioned by informed decisions from the outset. Late additions are costly and difficult to integrate with the architectural concept. -Multidisciplinary design is not a linear but an iterative process. Feedback loops and sequential stages are needed so as to contrast contributions from the different areas of expertise. The quality and robustness of the final design depends on how well the different inputs have been integrated. -Communication is the key factor. Lack of understanding has been clearly identified as the main barrier between the architect and the environmental consultant. Complex and prescriptive pronouncements result opaque and of limited use for the design team. Rationalization and graphic processing of parametric analysis facilitates communication and opens new paths for the architect to find the optimum solution for each design decision. The build environment is an interpretive task highly influenced by our ability to read spaces. Environmental data is not by definition the ultimate performance indicator. Recent experience has proven that such values are just triggers to develop communicative skills that can be translated into representative parts of the project, hence to generate performative “maps” ready to evolve according to the project’s necessities. Finally it is highly recommended for sustainable environmental consultancies to establish

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[1] Baker, N. and Steemers, K. (2000). Energy and Environment in Architecture. E & FN Spon Publishers, London. [2] Yannas, S. (2007) Environmental Design Support Tools . Lecture at the Environment & Energy Studies Programme. Architectural Association Graduate School [3] Yannas, S. (2007) Myths & Theories of Sustainable Architecture. Dispelling myths, assessing theories and practice. Lecture at the Environment & Energy Studies Programme. Architectural Association Graduate School. [4] Boude, K. (2007) Environmental Design working Models, Case studies 1. Lecture at the Environment & Energy Studies Programme. Architectural Association Graduate School [5] USGBC (2009) Sustainability Facility – press article. [6] Szokolay, S.(2004) Introduction to Architectural Science: the basis of sustainable design. Architectural Press, London [7] McMullan, R. (2002). Environmental Science in Building. Palgrave, London.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

What do young people tell us about sustainable lifestyles when they design sustainable schools? Post-Occupancy Evaluation of New Schools with the Participation of Children Andrea W HEELER1, Dino BOUGHLAGEM1, Masoud MALEKZADEH1 1

Department of Civil and Building Engineering, Loughborough University, Leicestershire, United Kingdom

ABSTRACT: The UK government created a unique educational opportunity with the recent school building programme. Its aims were described as transforming learning and embedding sustainability into the life experience of every child. However, how do young people understand these aims, and the concepts of sustainable lifestyles and sustainable communities, now they have begun to be translated into school design? This paper reports on the recently suspended programme and discusses the value of Post Occupancy Evaluation (POE) as a way of capturing successes and failures of what has been implemented so far. POE provides an opportunity for young people to critically engage with why our energy use and our relationship with the natural environment has to change. POE can also examine the gap between predicted and actual energy performance of a building and human behaviour is key in such investigations. The focus on innovative technologies is in danger of ignoring the human factors involved in reducing our impact on the environment. Current approaches used in Education for Sustainability can also ignore the complex social aspects of encouraging sustainable lifestyles. This paper describes an emergent POE approach developed and used to carried out research with young people in the UK using this method. It examines reoccurring themes across case studies and describes young peoples’ experience with contradictory adults’ behaviours. If we are to meet the needs of future generations, we will all have to be able to design for ourselves – albeit in negotiation with others – environments in which we can live in different ways. Participatory post-occupancy assessments hence have multiple benefits, whilst for architects, they provide feedback on the performance of buildings; for young people they are also creative opportunities to begin to explore sustainable development, with all the philosophical and political complexities this entails, and to begin to rethink and redesign their lifestyles. Keywords: energy, participation, post-occupancy assessment, children, schools

1. INTRODUCTION Developing initiatives that allow children to engage with architects and designers to design their own schools and to think critically about sustainable lifestyles, is an educational opportunity that can drive change in schools: innovative, collaborative and artbased research activities are ways to explore more authentic relationships with the environment. Ways that not only develop an understanding of energy efficient and sustainable architecture, or how architects design, but also to develop a critical relationship with some of the complex global and ethical issues of sustainability. The potential benefits for schools are both educational and environmental: children can discover their own sense of a relationship to the world and others and at the same time rethink and rewrite their own lifestyles. The approach developed within a workshop environment, which this paper examines, demonstrates the ease with which children can be inspired to both critical engagement with the problems of sustainability and to creative alternative designs of their environments. This contradicts common knowledge that children and young people lack motivation or interest in the problems of sustainable development; and suggests

an approach which may have significant impact in determining the difference between the predicted and actual energy performance of buildings 1.1. Building Schools for the Future Building Schools for the Future (BSF) was launched in 2004 to rebuild or refurbish every secondary school in England over a 15-20 years period. Local authorities would enter into publicprivate partnerships, known as Local Education Partnerships (LEPs), with private sector companies. Funding for BSF came from PFI and government funds, and was targeted at local authorities, with the most deprived schools first, through a standard formula using GCSE results and free school meal uptake. The environmental ambitions of the programme and its holistic intentions were evident from the outset [1]. However, in July 2010 it was announced that the £55 billion 20 year BSF programme was to be cancelled as part of a series of cuts by the new coalition government. Only schools that had already signed contracts would go ahead with their construction phases. At the point when the programme was cancelled, 185 schools had received BSF funding.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

George Osborne, the Chancellor of the Exchequer, argued that the scrapping of the BSF programme will help to reduce the cuts that would have otherwise been necessary to teaching budgets, Michael Gove, the Education Secretary, commented that the impact of the Spending Review on schools, would ensure money was spent more efficiently [2]. Nevertheless, the UK Government still require buildings to meet carbon emission reduction targets. Policy imperatives are still driving the need for accurate and holistic means of evaluating building performance and there is significant difference between the predicted and actual performance of the newly built schools. This paper argues that it is the school culture, demonstrated in the relationship between the ethos of the school and community values that plays the most pivotal role in determining the factors contributing to this difference. Working with children is a way not only to explore this school culture, but also to transform it. If architects are genuinely to build sustainable schools (putting aside for a moment the problem of what this actually means or indeed how we might measure it), we need integrated approaches to school design which include attention to the role school culture plays in determining behaviours and influencing the actual energy performance of schools.

2. THE SUSTAINABLE SCHOOL Today school buildings contribute around 2% of UK greenhouse gas emissions, roughly the same as all the energy and transport emissions of Birmingham and Manchester combined. This is equivalent to 15% of the country's public sector emissions [6]. The Sustainable Development Commission's carbon footprint for the schools estate has estimated that in England, the sector emits 9.4 million tonnes of carbon dioxide each year. Energy use in school buildings represents 37% of this. The recent UK Zero Carbon Schools Taskforce, set up to identify how to create low carbon and energy efficient schools, has identified many problems with the design of new ―sustainable‖ schools. Equally, within the educational context, the government's aim that every school would be a ―sustainable school‖ by 2010 has been described as over ambitious [3]. It has been argued that whilst the framework for sustainable schools extends the school's commitment to include care for people at a distance, to future generations and to the rest of the living world, the current drive towards greater individualism, illustrated through testing and competition contradicts and erodes this ambition [4]. An integrated approach to Education for Sustainability in the Sustainable Schools programme on the other hand, suggests that: thought needs to be directed to what and how students are taught (exploring sustainability through the curriculum); how the school campus is managed and led (through exemplar buildings and grounds); and how the school can act as catalyst for change in the wider community (through engagement with the community). These educational goals are constantly

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being undermined: by new buildings that are often far from exemplary in terms of their environmental performance; by parents travelling long distances by car; and by the schools themselves eroding an integrated approach by the privatisation of school catering and avoidance of locally sourced food [4]. There is a real lack of clear thinking about creating sustainable schools both in terms of architecture and education. There is also a worrying decline in attention to educational purpose within the educational policy context which shows a rise in the use of spatial language (and an interest in the effect of environment on learning), and a shift in emphasis from the activities of the teacher to the activities of the student. The concepts of ―environments for learning‖ or ―learning spaces‖ are examples [5]. What is evident is lack of clarity in the meaning of zero-carbon and even sustainability. What does behavioural change, and a consequent change in school culture, entail? However, the benefit of using the adapted POE method we developed is that it allows us to explore these questions with children and in so doing examine the performance of the environment in which this happens. This, we argue, addresses a significant need in understanding how to involve children and as a result demonstrates a demand children were enthusiastic to take on. 2.1. The Value of Post-Occupancy Evaluation Methods It is commonly known that discrepancies exist between predicted/optimised and actual performance of buildings, resulting in additional redesign and refurbishment costs. Whilst some of the causes of the performance shortfalls can be attributed to the inherent limitations associated with the use of simulation tools, other causes are related to less easily determined factors that come into effect during the construction, operation and influence by users (including children) of the building. It is evident that delivering and operating highly efficient buildings is a process that requires a holistic view of the building process [7]. Bill Bordass [8] argues that good building performance in practice requires: a good client; a good brief; a good team; specialist support; a good robust design; enough time and money; an appropriate specification; a good contractor; a wellbuilt well-controlled building with post-handover support; and. management vigilance to achieve a truly energy efficient environment. Within each of these requirements we could add ―sustainable‖. However, new ―sustainable‖ schools are uniquely problematic because, as Bordass states, the fabric performance is not as good in practice, the building systems and controls are too complicated; the response to patterns of use is poor - leading to avoidable waste; and, importantly policy factors driven by educational objectives are mandating more intensive use of energy [8]. The need for a holistic perspective towards the design of sustainable schools does seem obvious and engaging people in the problem could significantly reduce this demand.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

2.2. The Zero Carbon Schools Taskforce The Zero Carbon Schools Task Force was established in early 2008 by the Secretary of State for Children, Schools and Families, with the remit to advise on what needs to be done to reach the goal that all new school buildings will be carbon neutral by 2016. (The work of the group came to an end in December 2009). For the Zero Carbon Schools Task Force, the five steps necessary to achieving a zero or low carbon school also include behavioural change. Described as the Carbon Hierarchy, these are: engagement with school communities; reducing demand (assisted by engagement leading to behaviour change); driving out waste by better design (which will need more knowledge and skills in the design and construction industries); decarbonising school energy supplies; and neutralising any residual emissions [6]. The final report from the group argues that low and zero carbon will only be achieved if action is taken across a range of fronts including technical, financial and social. Whilst the Task Force was reporting during a period of intensive new building, it did also comment on the importance of reviewing use and demand in schools. In a climate governed by cuts in public funding this becomes even more significant: retrofit have a far greater impact than new build. Further recommendations include: that the Partnership (the delivery body for the Building Schools for the Future programme) develops a postoccupancy evaluation (POE) process for all schools within BSF and a methodology for an in-depth energy study which is applied annually to a sample of schools [Recommendation 25]. Other recommendations include: the gathering and publication of performance data to monitor progress [Recommendation 26]; a targeted programme of energy reducing refurbishment work (linked to behaviour change) to cut emissions in existing schools [Recommendation 27]; and education and engagement initiatives for staff, students and communities [Recommendations 3, 4, 5] [6]. The group suggest the active engagement of students and staff, a programme of behavioural change and a POE process for all new schools. But the limitation in time and scope of the work of the taskforce, means that there is no realistic suggestion on how this can be achieved in practice, or any mention of the barriers that the context and school culture can present. The apparently contradictory directions of behavioural change and technological innovation influencing policy and individual behaviour only demonstrates where the complexity lies. 2.3. Predicted Buildings

and

Actual

Energy

Use

in

A focus on the technological features in sustainable schools will not provide the answer to realising sustainable schools. Energy efficient building technology and ICT in new schools often does the opposite of what it should Presence detection in corridors can force lighting to come on during the day (children are first to demonstrate these contradictions to us). Bunn [9] argues for a sustainable design which is ergonomic and

democratic, design solutions that truly meets users' needs - not designers‘ beliefs or what teachers ought to have (whether or not they really want it or need it). For example, he writes: "Hand-held remotes have been given to school-appointed eco-warriors to control lights. Pupil power can be as powerful as BEMS when it comes to truly intelligent lighting control" [9]. There is increasing acknowledgment of the need to provide integrated approaches that address both technical performance and occupant behaviour [10]. And like many advocating behaviour change, Vale and Vale suggest a focus on facilitating change in occupants‘ lifestyles driven by ―ethical principles‖ rather than just changing building design [11]. For Leaman, Stevenson and Bordass, however, the future also lies in evidence-based qualitative and quantitative feedback as a routine part of their services and responsibilities [12]. Post-occupancy assessment methods are significant in that they provide such means to explore both qualitative and quantitative dimensions, and examine the human factors including the values of users contributing to the energy performance of buildings. However, using POE methods to work with the culture of organisations and investigate people's values and beliefs does also raise not just opportunities, but also methodological issues. POE methodologies can allow an examination of the physical, technical and management factors influencing the actual performance and they can also allow, in principle, an assessment of attitudes and perceptions determining the energy performance of buildings, providing the potential for an integrated approach. Whilst they are by definition methods that involve users of the school buildings being assessed, POE is yet to explore the problems and potential of methods focused on children within the context of sustainable school buildings. It is after all, one thing to advocate for the inclusion of children‘s perceptions in POE, but quite another to develop an approach which is both suitable and appropriate for their age and experience, and which allows them to engage critically with the problems of sustainable design and lifestyle change.

3. RESEARCHING WITH CHILDREN Those experienced in working with children suggest the importance of involving them in design and the legal imperative [15]. However, working with children can be a challenging experience for many and the entry of child actors into what is often generally understood as adult responsibilities and influence can be somewhat threatening. Adrian Leaman even argues that their role in postoccupancy evaluations can be limited [13]. Moreover, there is a wealth of literature to suggest that children, and even teachers, have limited knowledge of sustainability. Nevertheless, Chernley and Flemming advocate that involving children in consultations with architects – when the opportunity arises – has significant educational value. Central to their own research, was the observation that children and young people can engage with architects and other building professionals to explore the role of natural

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

daylight, natural ventilation, insulation, reducing energy demand and renewable energy technology in sustainable design [14]. Hence, whilst researchers in Children‘s Studies have developed ways of working with children in the context of designing a sustainable school [16]. Others have questioned some of these approaches and researchers‘ potential complicity in a simply political agenda: young people, are eager to absorb other people‘s preoccupations and prejudices; and (in a criticism of activities to use children as motivators of change) ‗…are not there to cure parents bad habits‖ [17]. Involving children as researchers in projects towards school change does, nevertheless, appear already to have a proven transformative potential [18, 19]. Frost argues that in pursuing an educational assessment, through what she calls an ―emergent collaborative action research methodology‖, knowledge generated was less partial, more contextualised and hence more valuable [20]. 3.1. The Method Based on a review of existing methods for POE research, and from those suggesting researching with children or co-research (and other broadly action research based methods) the authors devised an adapted POE method for schools. POE methods are fundamentally ―multi-modal‖ and approaches may include a single or a number of different ways to collect data, such as: pre-visit questionnaires; gathering technical data to establish construction, systems, etc.; semi-structured interviews with key stakeholders (client, designer, contractor, occupant, manager); field observations during walk-through visits; predicted and actual resource cost information; physical monitoring where necessary, including thermal imaging. One of these methods is free open questioning bringing out hidden factors and tacit knowledge not revealed by structured questionnaires, important we felt for our own research [10]. However, this raises some difficulties when working with children. Children‘s studies researchers have, for example, challenged the use of ―focus groups‖ as inappropriate [21]. Those working with children tend to use more art-based methods [22]. Nevertheless, Watson and Thomson describe a participatory ―walk-through‖ method which we felt could be appropriately adapted (with the addition of a video camera) to allow for open discussion and creatively engage children [23]. The use of open discussions, walk-throughs and art based methods adopted, formed the basis of our emergent participatory post-occupancy assessment methodology. The walk-through interview provided a spatial agenda and a performance opportunity to respond to – a chance to make a documentary with the video. This strongly contextualised the research results. Open discussion was also opportunity for storytelling and for critical engagement with some of the design problems in building sustainable schools. A final design task was added to give children a chance to reflect on the research exercise and ―to do being an architect‖. Conversations during activities, whether walk-throughs or during the drawing/design task were recorded, and selected dialogues transcribed. Analysis took the form of a fairly simple

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content analysis but the use of broadly action based research methods meant that the transformative aspect of the research project also played an important role in motivating engagement. Hence, our method consisted of the use of video making to facilitate the deeply context based discussion, the capture of these conversations which formed the basis of our analysis, and final drawings which produced by children, supported the findings. We discovered that children‘s story-telling was also often used as a way of explaining others energy behaviours or to convince others‘ about a new knowledge or a new concept. Narratives attempted to describe complex issues and often persuade others. Hence, we also attached particular importance to stories told by the children about their new school environment and energy behaviours. This was seen as a first crucial step in providing ways to productively engage with the issues and concerns of sustainability. Our nascent approach to post-occupancy assessment research is being developed to provide an integrated understanding of energy use in buildings. The dialogue of children and other users of the building provide essential clues to the factors contributing to the difference between the actual and predicted performance of new buildings. However, the methods we are developing also offer the potential for much more than this, they are opportunities: to explore children‘s relationship with their environment and to transform this relationship; and to provide the foundation for an integrated approach to building a sustainable school. Feedback methods are by their very nature ways to continuously learn about the performance of buildings and to understand people‘s behaviours within to those buildings. Adapted feedback methods also provide ways to begin to change those behaviours. 3.2. Results In all the case study schools children expressed some criticism of circulation routes and crowding. They had significant problems with the lunchtime experience, (many of the schools had been designed for different sittings to reduce the space needed in dining halls and yet the school programme had changed post-occupancy to allow for only one). Problems of littering also forced students to stay in crowded eating areas inside and not take lunch to the playing field or any other areas of the building. Children did not use the showers provided in the changing room (this was communicated as problems with privacy and time). Some of the toilets in all case studies were locked to prevent vandalism (some of the children reported that they never used the toilets in school time). Lights were left switched on at night time when the school was unoccupied and those in classrooms were used when deemed unnecessary by the children. Corridors and stairs were also observed to have artificial lights unnecessarily switched on during daylight hours. Computers and whiteboards were left on stand-by as a school rule. Many of the windows were being locked shut making opening them for natural ventilation difficult for

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

teachers and often prohibited for students. Automatic controls were commonly either not working or used incorrectly. Questioned on comfort one year 8 pupilparticipant stated: ‗In my Maths class Mr Smith [name changed] normally leaves the windows wide open and its really cold all the time [but] I'm quite warm on the left. That's because of the radiators... He puts the radiators on then has the window open’. The PFI arrangement was also observed to have a significant impact on the culture of the schools depending, to a greater or lesser extent, on the nature of the school leadership and relationship with the management company. In a discussion about the prohibition over drawings being stuck to the walls, which was described by pupils as a rule of the building management company, one Year 9 (13 year old) said: ‗It’s like living in a council house where you can’t do anything to it‖. Other stories that emerged from children focused on a convoluted system in place to maintain the building, the ―office to telephone‖ was perceived as a great distance away – Liverpool, Manchester, Cornwall and Scotland: ‗The changing rooms smell a lot because the drains get blocked and if something happens it means you have to ring up Liverpool to put it on the caretakers list that the drains need fixing because that’s where Headquarters are’ (Year 11 participant). Even the control of the temperature of the building in one instance was understood as dependent on the weather in Manchester, the reason why it was particularly unresponsive to the actual temperature outside. Hence, rules and regulations about the school environment were determined not only by teachers but by the higher authority of the building owners and ―care‖ eroded to an enforced responsibility for the others property. The school rules and regulations were a constant source of stories, but there was a tendency in the case study schools visited for schools to impose what was seen by the children as irrational rules and regulations and which were in fact adopted to restrict charges imposed for additional cleaning or repair, by closing the toilets, for example. Restricting the playground and other spaces during lunch and break times, was seen as ―stupid‖ by children. Nevertheless, children‘s own initiatives were also often frustrated by others: ‗...there are these recycling bins that after a year and a half we finally got in the school but there isn’t really enough of them round the school for people to know that they are there and use them’ (Year 11 participant). 3.3. Discussion With the new wave of school building and with an ongoing need to retrofit old buildings, children will grow up within architectural environments which pay significant attention to the idea of reducing energy consumption. Whilst many of the more hidden energy efficient design strategies architects use often go unnoticed in schools by children and adults alike, children are, nevertheless, quick to point out many of the more obviously wasteful energy behaviours happening in otherwise energy efficient schools: ‗They are telling us to be energy efficient but... They stand there in science and say you need to save

energy and then I say well turn your lights off... they are always banging on about it. They are always telling us to save energy but why not them (Year 9 participant). Asking children why adults are like this, is often met with idea of habit or ‗set ways‘. When asked if we should care more about the energy the school uses and be less wasteful, one participant states: ‗I think we should but we have gotten used to everything and don't want to go back to basics’ (Year 7 pupil). However, just by the nature of their new environments, different ideas towards energy efficiency will emerge and it is important that schools act to reinforce emerging lifestyles, and be more critical of adults ‗old ways‘. Whilst an increased motivation to care for a building and its environment could be seen as a positive contribution to a sustainable school and an element of a more sustainable lifestyle, it is important to note that where this is driven by rules and by penalties imposed on school budgets; and perceived as prohibiting the proper use of the building by children; it prevents children establishing their own ―authentic‖ relationship to the environment and thereby a deep or lasting critical perspective on the problems of sustainable development. Involving children in POE provides architects with: highly contextualised information about how a school is used; information about how to improve the quality of children‘s experience in school, both social and educational; information about how the school community is contributing to the energy performance of the school; and detailed and highly context dependent information about the factors contributing to the difference between predicted and actual energy performance. Adapted POE methods can also provide opportunities (and for some schools and some children these many be the only opportunities) to explore and reformulate the values and norms impacting on energy behaviours. The future potential this offers is significant. As the Zero Carbon Taskforce for Schools have recognised, it is only with a combined effort of design and behaviour that low carbon schools can be achieved.

4. CONCLUSION This paper argued that integrative approaches to the design of the built environment, whether new build, retrofit or maintenance, is essential if we are to genuinely approach the problem of building low carbon schools. Effective education for sustainability has to be participatory, inclusive and grounded in non-prescriptive, culturally sensitive and context dependent understandings of sustainability. Innovative POE methods are one such way to include children and school communities in shaping their environments and changing lifestyles. This research is part of an ongoing project and further case study workshops are planned. We will be returning to case study schools to explore and monitor potential changes in attitudes and behaviours as improvement take effect.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

5. REFERENCES [1] Blair, T. (2004), PM Speech on Climate Change 14th September 2004. [2] Vaughan, R. (2010), Osborne blueprint sees schools sigh with relief. TES, 22 October. [3] Scott, W. (2009), Critiquing the Idea of a Sustainable School as a model and catalyst for change. Transforming Our Schools [Lecture series]. The University of Nottingham. [4] Huckle, J. (2010), Sustainable schools: Teaching beyond sustainable consumption. [Online] School Design Futures: Seminar 2, 27th - 28th April 2010 2010, UKERC The Meeting Place, Available at: < http://www.ukerc.ac.uk/support/tikiindex.php?page=1004_MP_SchoolDesignFuture s > [Accessed 14 November 2010]. [5] Biesta, G. (2009), Creating spaces for learning or making room for education? Transforming Our Schools [Lecture series]. The University of Nottingham. [6] DCSF, (2009), The Road to Zero Carbon. The Final Report of the Zero Carbon Schools Taskforce. Available online at: http://publications.education.gov.uk [7] Bordass, W. (2009), Passivhaus schools: The route to low-energy schools in the UK? [Lecture] RIBA, London, 11 December. Presentation slides available online at: < http://www.usablebuildings.co.uk/Pages/UBEven ts.html> [Accessed 14 November ] [8] Bordass, W., Leaman, A. & Ruyssevelt, P., (2001), Assessing building performance in use 5. Building Research & Information, 29 (2), 144157. [9] Bunn, R. (2009), Sustainable Schools: Defining the Issues, [Lecture] RIBA, London, 11 December. Available online at: < http://www.usablebuildings.co.uk/Pages/UBEven ts.html > [Accessed 14 November 2010]. [10] Stevenson, F. (2008), Post-occupancy evaluation of housing. Power Point presentation available online at: www.usablebuildings.co.uk/Pages/UBEvents.ht ml < > [14 November 2010]. [11] Vale, B and Vale, R. (2010), Domestic energy use, lifestyles and POE: past lessons for current problems, Building Research & Information, 38: 5, 578 — 588 [12] Leaman, A , Stevenson, F. and Bordass, B. (2010), Building evaluation: practice and principles, Building Research & Information, 38: 5, 564 — 57 [13] Leaman, A. (2008), Unpublished interview by author. [14] Chernley, F., & Flemming, P., (2010), Engaging Pupils in the Design of Low Energy Building. CIBSE, 15 [15] United Nations, (1989), Convention on the Rights of the Child. Geneva, UN

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[16] Barratt-Hacking, E. (2009), Listening to Children: developing the sustainable school., Transforming Our Schools. [Lecture series]. The University of Nottingham. Available online at: [Accessed 14 November 2010]. [17] Scott, W. (2010), The Sustainable School: examining assumptions about young people's motivations, interests and knowledge. School Design Futures. Seminar 2, 27 - 28th April 2010 Available online at: [Video]. [Accessed November 14 2010] [18] Fielding, M, & Bragg, S. (2003), Students as Researchers: Making a Difference. Cambridge, Pearson Publishing. [19] Somekh, B. (2004), Inhabiting each other‘s castles: towards knowledge and mutual growth through collaboration. Educational Action Research, 2 (3), 357 - 381. [20] Frost, R. (2009), The HCD Student Partnership: Learning from Young Leaders of Research. In Fielder, J. & Posch, C. (eds.), Yes they can! Children Researching their Lives. Germany, Verlag. [21] Vogel, S. (2009), ―Focus groups with Children‖ In Fielder, J. & Posch, C. (eds.), Yes they can! Children Researching their Lives. Germany, Verlag. [22] Hall, C. Jones, K, & Thomson, P. (2011), ―Snapshots, illustrations and portraits: representing research findings‖. In: Thomson, P. & Sefton-Green, J. (eds.) Researching Creative Learning: Methods and issues. London, Routledge. [23] Watson, C. & Thomson, K. (2005), Bringing Post-Occupancy Evaluation to Schools in Scotland. Evaluating Quality in Educational Facilities. OECD Available online at: http://www.oecd.org

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Academic Advocacy: teaching outside the academy Alison KWOK1, Walter GRONDZIK 2, Bruce HAGLUND3 1

2

University of Oregon, Eugene, OR, USA Ball State University, Muncie, IN, USA, 3University of Idaho, Moscow, ID, USA

ABSTRACT: The transformation of our built environment to a low-energy, low-carbon-emissions future will rely on skilled teachers and professionals steeped in the knowledge of passive systems, building performance, and renewable technologies that can shape a beautiful and sustainable architecture of the future. For more than a decade the authors have collaborated to develop and conduct building performance workshops for a variety of audiences beyond the boundaries of their individual academic institutions. The motivation for conducting these workshops has been to transform the practice of architecture from the bottom up by training professors, practitioners, and graduate students (future professors and practitioners) to teach and design with building performance in mind. This paper describes the several types of workshops offered and provides a retrospective analysis of their effectiveness through anecdote, attendee evaluations, and workshop outcomes. The primary teaching workshops presented include the Agents of Change project workshops, which aimed to instruct teachers and their graduate assistants in hands-on methods of building performance evaluation and curriculum enhancement with a focus on performance issues; Tool Days, which engage various building sector professionals in hands-on building performance evaluation methodologies facilitated by graduate assistants who are refining their professional and teaching skills; and Zero Net Energy design charettes conducted with mainly professional audiences in architecture and engineering to enhance their understanding of the role of design in reducing building energy use, thus making zero net energy buildings possible. These workshops have been given to a wide variety of audiences in domestic and international venues. All of the workshops have produced tangible results and have been evaluated by the participants, but until now no comparative or holistic evaluation has been done. This paper offers analysis of the workshops and speculates on the way forward. Keywords: energy, carbon, comfort, building performance, pedagogy

1. INTRODUCTION Today’s students are the decision makers of the future. Beginning with the Vital Signs Curriculum Materials project [1] in 1992, the authors have adopted a charge to arm teachers and future practitioners of architecture with skills, tools, and experiences to document successful (and less than successful) stories of the built environment [2]. These early efforts spawned three trajectories that are reported in this paper. One effort, the Agents of Change project, expanded upon the Vital Signs Project by training faculty, and their teaching assistants (future architectural educators and critical practitioners), to assess building performance through on-site investigations. The Tool Day concept was formulated in a brainstorming session following an early Agents of Change workshop. While Agents of Change workshops focused on post-secondary architectural education, Tool Days were offered to a wide audience of design professionals (architects, engineers, building owners, consultants) and capitalized on the fun and intensity of learning from hands-on evaluations of exceptional buildings. Since 2001, Tool Days have been held annually in conjunction with the ASES solar conference and in other diverse locations, including Japan, Korea,

Hong Kong, and the U.K. In addition to the practitioners being targeted by Tool Days, educators were encouraged to participate and experienced teaching assistants were recruited to serve as facilitators for the investigating teams. The third area of education in the community includes a series of Zero Net Energy Design charettes launched in 2008 and presented by the authors with various colleagues to an audience of practitioners who deal with the built environment. These were developed and offered with the goals of addressing the targets of the Architecture 2030 Challenge [3] and the imminent need to design and build zero-energy, zero-carbon buildings.

 

2. AGENTS OF CHANGE 2.1.

Workshop intent

The Agents of Change (AoC) project expanded the approach of the Vital Signs efforts by training teams of faculty and their teaching assistants from various schools to assess building performance through on-site investigations. The Agents of Change project was funded from 2000-2005 by the U.S. Department of Education Fund for the Improvement of Postsecondary Education (FIPSE) to better prepare students as future teachers, architects, and

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stewards of the built environment. Over five years and two consecutive grants, the project conducted seven training sessions, and directly impacted more than 170 faculty and teaching assistants from more than 50 architecture programs. Participants were introduced to the skills and equipment needed to conduct investigations of actual buildings, carry out post-occupancy surveys, and develop curricular materials to implement in coursework at their home institutions. AoC generated a library of exemplar case studies [8] still shared on the Internet. The project also surveyed over 1,000 architecture students to ascertain changes in their attitudes, perceptions, and knowledge resulting from the AoC curricular infusion. Agents of Change has increased the pool of qualified architectural technologists and motivated graduate students to enter the teaching ranks; helping further the goal of training future generations of designers to create buildings that provide for human health and well-being while using energy responsibly [4, 5, 6, 7]. 2.2. Berkeley, California The initial AoC workshop, held at the University of California Art Museum in Berkeley, was a two-day event that set the format for the six workshops that followed (as summarized in Table 1). An overwhelming success, it involved graduate students and their professors, invited from nearby universities, using the Art Museum as inspiration and training ground for teaching and learning the nuances of a building’s environmental performance. This workshop was conducted as a proof-of-concept exercise to the funders (U.S. Department of Education), which fortunately did prove the case. 2.3 Ensuing AoC workshops In response to the trial run at Berkeley, the workshop format was expanded to three days to ensure adequate time for training, exploration, and reflection on workshop methodologies. The AoC imperative was to introduce methods of investigation that could be integrated into curricula in many universities in a range of formats. Curricular building studies could be as short as the AoC workshops themselves or as long as a full university quarter or semester. Table 1: Agents of Change Workshops

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Month

Year

Location

Nov

2000

Berkeley, CA

Jan

2001

Milwaukee, WI

Jan

2003

Portland, OR

Aug

2003

Oberlin, OH

Jan

2004

Phoenix, AZ

Oct

2004

Falmouth, MA

Aug

2005

New Smyrna Beach, FL

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Extensive information on the Agents of Change workshops, artefacts, and case studies can be found on the Agents of Change web site [8].

 

2.4 Agents of Change reflections Do we know more about buildings than we did ten years ago? Yes and no. In the last ten years, the US Green Building Council launched the LEED rating systems and put in place requirements for commissioning. We are moving closer and closer to long term commissioning as a way of ensuring high performing systems. Agents of Change continues to provide a path for students (and faculty) to go into actual buildings, carry out an in-depth investigation on a topic of interest, and embed results into their long-term memory. The authors have found that students have better comprehension of the concepts and principles explored during their case studies than they did on quizzes and exams. In fact, this long-term memory boost has proven applicable to studio situations, where certain concepts and strategies are actively referred to in studio projects. A number of graduate students trained at one or more of the training workshops have entered academia as faculty—a direct indicator of success. One participating junior faculty expressly benefitted from the curricular experience—via an expanded network of contacts and by sharing teaching stories. There continues to be a need for training outside of the academy, not simply because of an infusion of new low-cost equipment (e.g. micro-dataloggers, infrared cameras, light meters) but in terms of setting up the investigation, stating a hypothesis, and developing an appropriate methodology for problem solving. Whether finding the amount of moisture in a wall, infiltration rates, lighting levels, or occupant comfort, methodologies need to be carefully structured and tailored to each specific situation. 

3. TOOL DAYS Tool Days offer the experiences of the Agents of Change (AoC) workshops, condensed to a singleday event tailored for practitioners to allow them to learn selected building performance investigation methods quickly and efficiently. We found this intense experience, conducted in an interesting building, to be very effective in inspiring learning and accomplishment because of the real-time, onsite learning [9, 10, 11]. See presentations from various Tool Day teams that are archived on the Tool Day web site [12]. 3.1. Washington, DC The long-running series of annual SBSE/ASES Tool Days began at the National Building Museum on April 22, 2001. The event was organized by the authors under the auspices of the AoC project, National Building Museum (NBM), and Society of Building Science Educators (SBSE) and held in conjunction with the American Solar Energy Society’s (ASES) Annual Solar Conference. Five investigating teams of five to six participants were led

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

by faculty/student duos. The teams were largely composed of students and faculty with one or two practitioners. The day’s activities began with a tour of the museum led by Martin Moeller, NBM Executive Vice President, and an introduction to the hand-held instruments and methods of investigation to be used later in the day. During a working lunch each team formed a hypothesis and methodology to guide their afternoon’s investigation of the building. Late in the afternoon each team had the opportunity to present its results to the whole group. The workshop was enthusiastically received. The teams conducted their investigations while the museum was open to the public, adding a bit of theatre to the day, exemplified by the team that used a dozen helium balloons to raise a string of HOBO data loggers to the ceiling of the museum’s great atrium (to the great delight of children). This success inspired us to continue to offer annual Tool Days in buildings of interest to integrated professional and academic audiences in cities across the country over the following decade as summarized in Table 2 and detailed at reference 12. Table 2: SBSE/ASES Tool Days

Year

Subject Building

Attendance

2001

National Building Museum, Washington, DC

29

2002

Patagonia Service Center, Reno, Nevada

22

2003

UT Solar Decathlon House, Austin, Texas

40

2004

The Brewery Blocks, Portland, Oregon

35

2005

Florida Solar Energy Center, Cocoa, Florida

19

2006

REI Store, Denver, Colorado

32

2007

Cleveland Environmental Center, Cleveland, Ohio

18

2008

UCSD SAS Facility, San Diego, California

19

2009

Market Arcade, Buffalo, New York Cronkite School of Journalism, Phoenix, Arizona

14

2010

19

In 2005 after four successful SBSE-sponsored events, we offered Tool Day as an official ASES workshop in an attempt to attract more nonacademic participants. The overall number of attendees decreased, but a more diverse audience participated. We continued to thrust graduate teaching assistants from schools of architecture into the role of workshop facilitator to help them gain teaching experience and accelerate their learning through greater responsibility for the hands-on teaching/learning situation.

3.2. Tool Day reflections We have conducted participant evaluations of the Tool Days in order to determine their effectiveness. A sample of 41 attendees at the San Diego, Cleveland, Buffalo, and Denver Tool Days revealed that all rated the hands-on experience as either very or moderately effective. A vast majority (78%) reported that they felt capable of passing on their knowledge of tools and methods to others—49% in their practice, 37% to train others, 29% to their students, 24% to effect change in architectural or engineering education, and 20% for their personal use. Such evaluation feedback imparts confidence that our goal of improving both teaching and practice is being effectively addressed by Tool Day workshops.

4. ZERO NET ENERGY CHARETTES 4.1. Portland, Oregon The first zero net energy charette conducted by this group was held in Portland, Oregon on March 21, 2009 [13]. The charette was underwritten by the Northwest Energy Efficiency Alliance’s BetterBricks program, Northwest Natural Gas, and the Van Evera Bailey-Oregon Community Foundation Faculty Award via the University of Oregon Department of Architecture. Twenty-five architects and twenty-five engineers from professional firms in Portland were invited to participate, allowing the formation of interdisciplinary teams (much as would occur in an integrated design project setting). Several collaborating facilitators were actively involved along with the authors: Nicholas Rajkovich (Pacific Gas and Electric) and Michael Utzinger (University of Wisconsin-Milwaukee) provided workshop content and charette structure and Bruce Dobbs (Northwest Natural) assisted with attendee and site coordination. This first zero net energy charette began with a series of short presentations intended to provide an introduction to zero net energy buildings and their design. This introduction was followed by a 2 2 description of the project—an 1860 m (20,000 ft ) urban office building for a design firm. Attendees were assigned to teams (around five per team) and each team was assigned a climate (Atlanta, Georgia; Los Angeles, California; Minneapolis, Minnesota; New York, New York; and Portland, Oregon). Individual team members were asked to assume the roles of owner and facility manger; architect and structural engineer; mechanical, electrical, and energy engineer; civil engineer and landscape architect; and contractor and subcontractor. Following the workshop introductions, the program transitioned into a working charette session that culminated in the presentation of a design proposal by each team. The facilitators served as resource personnel for the teams as they developed their respective design solutions. Discussion of the design implications of a zero net energy performance target was an integral part of the presentation process. The fundamental difference between this design situation and a conventional (moderate energy

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performance) design situation was the expected outcome—a zero net energy building. To accomplish this objective the design teams had to balance annual energy consumption (as a result of heating, cooling, lighting, and plug loads) with annual on-site energy production (almost universally from a PV array). Load reductions translated to smaller PV arrays. Increased PV size allowed less aggressive load reduction. The design teams were responsible for both building energy consumption and production. Numerous solutions were presented, but none were “conventional.” Getting to zero net energy in this size/type project proved to be possible, but not easy.

Anna Maria Orru (practitioner from the UK/Sweden) and Margot McDonald (Cal Poly San Luis Obispo) joined as facilitators. Alison Kwok and Nicholas Rajkovich were unable to participate. As with the previous two charettes, this workshop was sold out (although attendance in each charette was limited to fifty due to the hands-on nature of the effort).

 

4.2. San Francisco, California The second zero net energy design charette was held in San Francisco, California, on April 29, 2009 in conjunction with the national AIA Convention. Offering this charette as a continuing education workshop via the American Institute of Architects changed the attendee dynamics. The workshop was attended almost exclusively by architects, reducing the interdisciplinary character experienced in the Portland workshop. In addition to the authors, facilitators for the San Francisco program included Nicholas Rajkovich, Muscoe Martin (practitioner from Philadelphia, Pennsylvania), and Bill Burke and Anna LaRue (both with the Pacific Energy Center). The charette was held at the Pacific Energy Center, which eased logistics and provided access to useful resources (including the Internet). The structure of this workshop was very similar to that of the Portland workshop. Teams were formed and climates assigned. Discussion was an integral part of the team presentations that concluded the chartette. The results of the Portland and San Francisco charettes are published in reference 5. Subsequent to these workshops, University of Oregon architecture students analysed the results with Design Builder software [14]. The students found that the designs didn’t meet the zero net energy goal, but were all between EPA Target Finder’s 50% and 90% energy reduction goals [15]. As an example, the target and modelled energy utilization indices (EUI) for the four Portland, Oregon designs are shown in Figure 1. Remember that the designs were accomplished in a few hours without the aid of modelling tools to test assumptions and tweak enclosure and environmental systems. These are good preliminary outcomes. 4.3. Miami Beach, Florida The group’s third zero net energy charette was held in Miami Beach, Florida on June 9, 2010. This charette was a follow-up to the workshop held in San Francisco and was also conducted as a continuing education offering under the auspices of the AIA Convention. Attendee demographics were similar to those of the previous AIA workshop and the structure was similar—although a discussion of plug loads was added to the introductory presentations.

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Figure 1: EUIs for schematic designs for Portland, Oregon, compared to EPA Target Finder Goals for energy reduction [13, 15].

4.4. Charette reflections The zero net energy charettes are intense. They focus on performance outcome paradigms that are new to most participants. Because of the limited time available, the performance of team solutions is not “verified” by computer simulations. Design decisions must be made by informed intuition and the proposed solutions are “evaluated” by the collective experience of the facilitators. Although somewhat disconcerting to some participants, this mode of decision making and reflection is not unreasonable and mirrors what might be done in many firms not yet engaged in an integrated design practice. Passive solutions are of particular value in a zero net energy project—as they displace purchased (non-renewable) or expensive site-produced energy, which is essentially the name of the game. Daylighting plays a particularly important role in the passive systems line-up. Success or failure in rationally reaching zero net energy status lies in the first 30-minutes or so of this design charette as the building massing and orientation are established. This is not the norm for a design process that depends upon technological solutions appended during design development.

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In general, participant evaluations for the three charettes have been quite good. A fair degree of frustration with the scope and novelty of the problem, however, can be read between the lines of the feedback. Upon reflection these concerns are likely inevitable with a time-constrained, complex, novel design problem. Although a two-day workshop format would ease time concerns and provide more opportunities for reflection, such a time commitment is not very palatable to professionals or compatible with the venues used to date. Use of computer simulations would likely assuage doubt about the accuracy of energy performance results, but there is no software program that could be taught and run in the time frame available. We believe that the intent of the charettes has been accomplished—namely providing designers with a window to an emerging new world of design expectations and the confidence to not shy away from the view. All of the authors have offered zero net energy courses in their home university settings. Results from these semester-long offerings (both studio and elective seminar formats) mirror those seen in the professional workshops. Additionally, the workshop was given to a group of 20 students and professionals in Quito, Ecuador (using Quito and Portland climates) with equal acclaim and similar results. The topic and presentation format are quite robust, appealing to a diverse worldwide audience.

5. CONCLUSIONS Agents of Change demonstrated that a lot can be learned from focused investigations of occupied buildings. Simple instrumentation can yield valuable insights into building performance. Development of a hypothesis to guide investigations is important. A hypothesis limits random wanderings and musings— which is in fact good as an investigation develops. Probably half of the hypotheses developed by case study teams have been incorrect—proven false by the team’s own investigation. This is both great (learning is occurring) and important to note (the hypotheses are often an extension of intuition about how things work, and intuition is quite often proven wrong). Tool Days, as an ongoing series of Agents of Change studies, present essentially the same findings. Using real occupied buildings as laboratories for understanding building performance is a brilliant idea—thank you Vital Signs. As the newcomer to our array of advocacy offerings, the lessons from the Zero Net Energy workshops are still being digested. What we have seen so far is that without need of radically different tools or skills designers can develop high performance buildings; a fair amount of encouragement is necessary to convince many designers of their capability to engage zero net energy; we need better schematic design phase energy modelling tools; aspects of building performance (such as plug loads) that have historically been beyond the scope of design cannot be ignored by the design team.  

The arc of our advocacy has responded to the realization that the climate change scenario demands an ever more immediate response. Initially, Vital Signs (our roots) focused on training those who were already teaching to understand the nuances of building performance and to pass this understanding on to their students who would influence practice years down the road. Agents of Change expanded the breadth of the Vital Signs effort to include both current and future teachers (and future practitioners) so that more future educators and practitioners would be advocating a greener future. Tool Days allowed us to reach out to those already practicing, while also engaging future teachers and practitioners in the learning process. Finally, the Zero Net Energy design charettes were aimed directly at those empowered to make changes happen in practice.

6. ACKNOWLEDGEMENTS We acknowledge the enthusiasm and support of the many organizations, a legion of colleagues, and thousands of people who have funded, facilitated, and participated in the delivery of these extracurricular academic services from Agents of Change to Tool Days to Zero Net Energy. You know who you are and we thank you profoundly!

7. REFERENCES [1] The Vital Signs project www site: http://arch.ced.berkeley.edu/vitalsigns/. [2] Grondzik, W., B. Haglund, and A. Kwok, “From Vital Signs to Practice: A Technology Transfer Case Study,” Proceedings Building Envelopes IX Conference, Clearwater Beach, FL 2004. [3] The Architecture 2030 www site: http://www.architecture2030.org/. [4] Kwok, A., W. Grondzik, B. Haglund, and T. Peters, “The Agents of Change Project: Changing Perceptions of Building Performance,” Proceedings of 28th National Passive Solar Conference, 2003. [5] Kwok, A., W. Grondzik, and B. Haglund, “Infusing POE into Architectural Education,” Proceedings Closing the Loop Conference, Great Windsor Park, UK, 2004. [6] Kwok, A., et al, “The Agents of Change Project: The Power of Peer-to-Peer Teaching,” Proceedings ASES National Solar Conference, Portland, OR, 2004. [7] Kwok, A. and N. Rajkovich, “Agents of Change: Training Future Teachers, Architects, and Stewards of the Built Environment,” in Case Studies Starter Kit, AIA/ACSA Teachers Institute at Cranbrook, July 10, 2004. [8] The Agents of Change project www site: http://aoc.uoregon.edu/. [9] Haglund, B. and D. Wilson, “Workplace Performance Monitoring: Analysing the Combination of Physiological and Environmental Sensory Inputs,” Proceedings IEE Wearable Computing Conference, 2003.

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[10] Haglund, B., “The Workplace Performance Projects—A Case Study in Research Collaboration,” Proceedings ARCC/EAAE Research Conference, Dublin, IE, 2004. [11] Haglund, B., W. Grondzik, and A. Kwok, “Tool Days: Translating Architectural Education Research into Practice,” Proceedings ARCC/EAAE Research Conference, Dublin, IE. 2004. [12] The Tool Day www site: http://www.sbse.org/toolday/. [13] Kwok, A., Zero Net Energy Workshop and Design Charrette, Lulu Enterprises, Inc. http://www.lulu.com/product/file-download/zeronet-energy-workshop-and-designcharrette/5093775. [14] DesignBuilder www site: http://www.designbuilder.co.uk/. [15] U.S. EPA Energy Star Target Finder www site: http://www.energystar.gov/index.cfm?c=new_bld g_design.bus_target_finder.

 

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Is Solar Design a Straitjacket for Architecture? Tiffany OTIS1 1

Graduate School of Design, Harvard University, Cambridge, USA

ABSTRACT: This paper seeks to investigate whether the precision of design tools used to meet solar requirements, in particular those related to the heating potential of sunlight, act as a straitjacket on architectural form. In order to determine this, two groups of students were asked to design massing models satisfying a set of physical and solar criteria, for one particular site. The first, Group A, had no recourse to solar design tools, while the second, Group B, were trained to use the site specific solar design tools that were developed in this paper. These comprise of a diagram showing the intensity of solar radiation incident on vertical surfaces facing all 360 degrees on a site and interactive images showing the amount of time different parts of a model are in shade. The models from both groups were evaluated based on their adherence to solar criteria and geometrical diversity. Group B models showed a lower proportion of solar design deficiencies compared to Group A models, while also demonstrating more geometrical creativity. The fact that the Group B models did not converge onto an optimal solution, they were more diverse than the Group A models, shows that the use of more precise solar design tools actually helps to broaden the range of architectural form. Keywords: solar, constraints, massing, design, tools.

1. INTRODUCTION This paper explores the question of whether the precision of the solar design tools used by architects at the building massing stage significantly constrains the range of forms available to the designer, or if they in fact may broaden architectural expression through the relative ease with which they allow for experimentation and rapid validation of uncommon geometries. When considering sunlight and architecture, the implications are vast, however, this investigation limits its scope to the heating potential of sunlight as it relates to architecture. In order to evaluate how solar design tools may affect form, an experiment is conducted wherein architecture students are each asked to create a massing model for a particular site. The model has a set of geometric and solar requirements and the students are divided into two groups: the first, Group A, which must design using their personal knowledge of solar strategies, and the second, Group B, who are provided with two solar design tools and taught how to use them in order to create a massing model. The models were then evaluated for adherence to solar criteria and geometric diversity. The presence (or absence) of formal variation in the Group B design models compared to Group A models will show whether or not additional precision in solar design can act as a straitjacket on basic architectural massing.

2. TOOLS PROVIDED FOR GROUP B 2.1. Polar Radiation Diagram The polar radiation diagram (Fig.1) provides information regarding the particular solar conditions found on a site. It takes into account the effects of local cloud cover, surrounding buildings and landscape features on the intensity of solar radiation and attempts to illustrate, in one image, the variation of this contextual radiation over the course of the year. The form of the diagram is inspired by Olgyay's

axial charts [1] which plot radiation in a circular manner, while the data synthesizes ideas of regionalism, as propounded by Frampton [2] and time as explored by Kleindienst, Bodart and Andersen in their temporal maps [3]. The values shown on a polar radiation diagram are the sum of the direct, diffuse and reflected components of the sun at a particular site. The diagram shows the intensity of solar radiation incident on vertical surfaces facing all 360 degrees (like a wind rose), which is more relevant for early building massing and orientation than a single horizontal value.

Figure 1: Polar radiation diagram recorded at 3m, overlaid on its corresponding site. Inner ring=winter, centre ring=spring/fall, outer ring=summer, dotted line= 3000Wh/m2/day reference value

The average seasonal daily radiation values (winter, summer and shoulder) calculated at fifteen degree intervals are obtained through a Daysim [4] simulation, and plotted on a circular diagram overlaid on a plan of the building site. The points are joined through a curve, and each season is thus represented by a ‘circular’ shape. The magnitude of

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the daily radiation falling on a surface facing a particular direction is represented by the distance from the point on the curve that intersects the normal of this direction to the centre point of the diagram. Effects of surrounding buildings on a building site and ideas about optimal orientations for different seasons can be gleaned quickly from this diagram. 2.2. Ecotect Shadow Range Images The built in shadow range module in Ecotect [5] produces hourly shadow images (Fig.2) which are rich in information for designers. On these images, each hour that a surface is in shade is represented by one tone of grey. Thus, the depth of the shade of grey on a given area represents the fraction of time that this area is in shade. From a solar perspective, if the goal is to avoid solar radiation on a building’s facade, then any white or light grey surfaces signal problem areas. (Note that amount of shade is not to be confused with amount of solar radiation; although two equally coloured surfaces receive the same amount of hours of direct light, they do not necessarily receive the same amount of solar radiation.) With these images, the general massing of a building as well as the sizing of architectural elements can be tested rapidly to determine if they are too large, too small, oriented in the wrong way, and so forth, and then adjusted by eye until the desired effect is reached.

3.2. Methodology Students having completed or who are currently in the process of completing a masters of architecture degree were each asked to build a massing model on a particular site according to the guidelines outlined above. Group A, the control group, were asked to complete the massing model using only a stereographic diagram and their own knowledge of best solar design practice. This group represents the ‘typical solar designer’. Group B, the experimental group, received brief training in order to be able to complete their massing models using the polar radiation diagram and Ecotect shadow range analysis images. (In brief, this involves sketching initial ideas on the polar radiation diagram, building a rough 3D model based on these ideas and evaluating performance vis-à-vis the design goals using Ecotect shadow range images, and modifying the model as much as necessary until results are judged satisfactory.) In order to keep designs on an equal footing, all participants were asked to complete their models within half an hour. 3.3. Hypothesis It is expected that the models produced by the Group A will be similar in their formal strategies whereas Group B will exhibit a broad array of arrangements and approaches. The reasoning is that the design tools will provide Group B participants with feedback rendering them more confident in the performance of their models and thus comfortable with straying from the 'tried and true' south facing courtyard form. 3.4. Evaluation Method Before being evaluated, each submitted model is checked for meeting volume and other basic criteria. Then, evaluation proceeds on two faces: the evaluation of solar performance with respect to the guidelines (maximize solar radiation in winter and minimize solar radiation in the summer on both facades and the designated outdoor space) and the evaluation of geometric diversity (facade orientation, orthogonality and courtyard orientation) between Groups A and B.

Figure 2: An Ecotect shadow range image for June 21st

3. THE DESIGN EXPERIMENT 3.1. Massing Model Guidelines Guidelines for the massing models to be created by the two groups are: a volume of approximately 75 3 000m , within a maximum buildable envelope of 30m x 77m x 64m, meaning that the building volume will end up filling approximately 50% of the buildable envelope. Additionally, an exterior space or courtyard 2 of at least 200m is required. The building's shape must contribute to fulfil the following solar requirements: maximize the amount of sunlight incident on facades and the designated exterior space during the winter, while minimizing the amount of sunlight incident on facades and the designated exterior space during the summer.

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4. RESULTS 4.1. Solar Performance Evaluation Ecotect shadow range images spanning from 7:00 to 19:00 with one shadow cast every hour are taken of the primary solar facades (east, south, west) and of the designated outdoor space on December 21st and June 21st. They are used to visually evaluate the solar performance of the massing model submissions based on the four performance criteria listed in the guidelines: maximization of sun on facades in winter, maximization of sun on an exterior space in winter, minimization of sun on facades in summer, and minimization of sun on an exterior space in summer. Each model is given a score of -1, 0 or +1 to describe their performance in each category. In the two winter categories, where the length of day is just under 9 hours, a score of -1

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(unsatisfactory) is given for a predominance of 6-9 hours of shade, 0 (successful) for 3-5 hours of shade and +1 (superior) 0-2 hours of shade. While in the summer categories, with a day length of just under 16 hours, a score of -1 is given for a predominance of 0-3 hours of shade, 0 for 4-7 hours of shade and +1 for 8 or more hours of shade. The scores from the model performance analysis were tallied and are reported for Group A models (Fig.3) and for Group B models (Fig.4). Compared to Group A models, Group B models have both a lower proportion of unsatisfactory designs (3.6% vs. 20%) and a higher proportion of superior performance (32% vs. 20%).

4.2. Geometry Analysis The orientation of model facades in terms of two ‘default’ categories was quantified: facades parallel to site boundaries and facades facing south/north. (Note that on this site, street orientation does not correspond to north/south orientation). In these measurements, one unit of facade corresponds to one length of the site. Thus, a model whose four sides are parallel to the site boundaries receives a count of four. Facade orientation in Group A models (Fig.5) is spread, but there is a strong preference for building parallel to the site boundaries. The opposite is true for Group B, where there are no models with a 4.0 designation (Fig.6).

Figure 5: Group A facade orientation

Figure 3: Group A performance graph

Figure 6: Group B facade orientation

Next, models were analyzed visually and their relative ‘orthogonality’ graphed. Models which, in plan view, possessed no right angles received the designation ‘none’. Those which were formed exclusively of right angles received the designation ‘all’. The models which fell in between these two groups were categorized as having either ‘few’ (under 50%) or ‘many’ (over 50%) orthogonal faces. Group A models (Fig.7) show a strong tendency towards orthogonality, while Group B models (Fig.8) are less conventional. Figure 4: Group B performance graph

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Figure 7: Group A orthogonality

Figure 10: Group B angular facade orientation

The range of orientations from which each exterior space or courtyard could receive sunlight was measured. This information was tabulated along with courtyard performance and whether the space was open to the elements or sheltered by an overhang. Both Group A and Group B results show the same preference for openings ranging from south-east to south-west.

5. CONCLUSION

Figure 8: Group B orthogonality

Model facades are further analyzed in terms of their specific orientation. The area of facade area facing in any given direction is tallied and presented as a percentage of the total facade area of the models in the group. By expressing results as a percentage, differences in total surface area between groups A and B do not affect the results. Group A (Fig.9) and Group B models (Fig.10) both favour orientations which are parallel to the street. The orientation of Mode B models is, however, more spread out over the range.

Figure 9: Group A angular facade orientation

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Do solar design tools, in their ability to allow architects to be rather ‘sophisticated’ in regard to massing buildings for sunlight, in fact significantly limit the geometric diversity of the architecture that can be produced on any one site? The results show Group B models outperforming Group A models on all counts. The solar performance of Group B models is superior to Group A models on all points in an evaluation of four solar design criteria, showing that the tools are in fact effective. Group B models are also more creative from a geometrical perspective. They orient themselves in a variety of ways in order to optimize solar control and rarely accept the default ‘parallel to road’ condition that was most often adopted by Group A models. The more unconventional geometries of Group B models (not parallel to road / not facing north or south) are also due to the fact that the design sequence, especially the Ecotect shadow range images, allows one to confirm with great speed whether or not an unconventional move works. With such large discrepancies between Group A and B models, in both geometry and performance, it can be concluded that a ‘blind eye’ approach to sunlight design, using general rules of thumb without any recourse to visualizations, is limiting in terms of the array of forms that the architect feels comfortable using, while the instantaneous and highly visual approach of Group B, which provides site and model specific feedback, results in not only better overall performance, but in the tendency to experiment with form. Most important is the fact that the facade orientations of Group B models are actually more diverse than Group A models. If there were an ‘optimal’ solution for this exercise, one would expect the exact opposite result: with the Group B

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orientations converging onto one or several key orientations with the Group A orientations being more disperse throughout the range. Since this is not the case, it is clear that there are a variety of ways to design for the sun on a specific site. Hence, given the proper design tools, solar design is not a straitjacket for architecture.

6. ACKNOWLEDGEMENTS Thank you to all of the students who participated in the model building exercise and to Christoph Reinhart for his support and guidance throughout.

7. REFERENCES [1] Olgyay, V. (1973). Design with Climate: Bioclimatic Approach to Architectural Regionalism. Princeton: Princeton University Press. [2] Frampton, K. (1987). Ten Points on an Architecture of Regionalism: A Provisional Polemic. In: Architectural Regionalism: Collected Writings on Place, Identity, Modernity and Tradition. New York: Princeton Architectural Press. [3] Kleindienst, S. Bodart, M. & Andersen, M. (2008). Graphical representation of climatebased daylight performance to support architectural design. Leukos. 5 (1) p.39-61. [4] Graduate School of Design, Institute for Research in Construction and Fraunhofer Institute for Solar Energy Systems (2010). Daysim 3.0 (beta). [WEB] [5] Autodesk (2009). Ecotect Analysis 2010. [WEB] Autodesk Inc.

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Designing for Sustainability: Pedagogical Challenges and Opportunities ANDREW GIBSON1, SERGIO ALTOMONTE1, PETER RUTHERFORD 1 1

Department of Architecture and Built Environment, University of Nottingham, United Kingdom

ABSTRACT: Sustainability has belatedly become a seemingly ubiquitous presence within formal educational institutions. The scale of the threat to life systems of the Earth, international directives concerning the pursuit of sustainable development, and growing professional imperatives, have all contributed to this state of affairs. Furthermore, it is widely recognised that educators, practitioners and students within the built environment play a key role in engaging with the sustainability agenda. However, the concept is inherently imprecise and largely defies consensus beyond a relatively shallow one. It seems clear that any ambition to promote a really deep engagement with questions of designing for sustainability is confronted by appreciable and multi-layered pedagogical challenges. Educators need to understand the complexities of student motivation and negotiate with its multiple dimensions. Logistical factors and attitudinal approaches equally impact upon effective teaching and learning of sustainability. At the broader curriculum level, it is frequently argued that educating, and indeed designing, for sustainability, is best tackled and understood within a more fully integrated, multi/inter/transdisciplinary framework. This paper will consider developments in this area looking at the challenges and potentially rich opportunities for pedagogical development in order to better face the challenge of designing for sustainability. This serves as a framework for the research carried out during the initial stages of a PhD project. Keywords: sustainability, pedagogy, interdisciplinarity, design, built environment

1. INTRODUCTION Education in architecture can be ascribed a vanguard role in promoting sustainable development; for example, in helping to develop the skills and attitudes necessary to engage with its environmental, economic and social dimensions [1]. Moreover, architecture professionals, educators and students are surely compelled to confront how best to respond to the challenge brought by climate change and resource depletion. Recent drivers for change at national level in the United Kingdom include the Government Sustainable Development strategy (2005), with its stated aim of producing sustainability literate professional graduates, and the earlier ARB/RIBA Criteria for Validation (2002) which laid particular stress upon the goal of an integrated, studio-led understanding of environmental sustainability [2]. However, such necessary attempts to promote deep, critical engagement with environmentally responsible architecture and, indeed, to integrate sustainability issues within architectural curricula, meet with a raft of pedagogical challenges. For example, there is a long recognised split in architectural education between the technical and theoretical domain and the creative practice of the design studio [3]. Educationalists and architects are increasingly considering if the size and nature of this physical and cultural gap requires a pedagogical overhaul, not just in terms of tools and strategies but in methodology and models of curricular structure [4, 5]. It is also being increasingly recognised that engaging with the complexities and multiple dimensions of sustainability invites, and arguably demands, that teaching and learning take place beyond, and overtly transcends traditional,

disciplinary “silos”. However, any serious attempt to embed sustainable principles and practices into an architectural education must also address the impact of ethos and motivation; this involves questions of how and why students learn. Designing a curriculum for sustainability therefore faces stiff challenges; but simultaneously it can be argued there are rich pedagogical opportunities that are informing practice and stimulating further research and collaboration between educators involved in schools of architecture. In positing the title „designing for sustainability‟ there are many possible conceptions and interpretations of the terms, which at times may lead to misunderstanding. This paper will suggest that „designing for sustainability‟ can legitimately focus upon pedagogies that seek to more effectively engage with sustainability issues and principles and integrate these into architecture curricula.

2. DESIGNING FOR SUSTAINABILITY The act of designing can be ascribed a broad remit, in part justified by the complex and multifaceted nature of the central concept and driver: “the sustainability context expands the boundary of what design is, what it does and who is involved” [6]. The design project is here considered as being located within Higher Education Institutions and all parties involved in critically examining and reflecting upon educating for sustainability: indeed, “all occupations engaged in converting actual to preferred situations [may be said to be] concerned with design” [7]. The substance of such conversion in this regard is inevitably a matter of profound controversy and beyond the ambitions of this paper. However, it will be concerned with pedagogies and curriculum

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initiatives which aim to better integrate sustainability, facilitate critical thinking and foster creativity in integrated environmental design teaching [8]. It is also clear that designing for sustainability will need to make connections, understand processes and pool skills and expertise which cut across what have sometimes been considered rather sacred disciplinary boundaries. In this sense, design is an act of synthesis to be informed and shaped by multi/inter/trans-disciplinary research.

3. SUSTAINABILITY AS A PROBLEMATIC CONCEPT Before discussing multi/inter/trans-disciplinary possibilities, it is worth unpicking the central, „problematic concept‟. It is generally agreed that sustainability within architectural curricula must confront social and economic, as well as environmental dimensions. However, sustainability remains a slippery, imprecise concept and should, indeed, be immediately recognised as a social construct [9]. The inherent lack of conceptual clarity raises concerns and can lend itself to a shallow consensus regarding the potentially prescriptive aims of educating for sustainability [10]. It may also be felt that there is a level of contradiction between the wide scope for interpretation and the project to develop a sustainability literacy which is strongly promoted by educationalists and echoed by increasing numbers of employers and practitioners [11, 12]; after all, we generally think of literacy as developing a facility with a common language which, whilst fluid, is nevertheless grounded in particular rules and codes. Equally concerning is the very word “sustainability”, which conveys an impression of „continuously carrying on‟; this, in itself, obscures the qualitative dimension of that which is to be sustained, or the extent to which it is to be gauged by such equally subjective measures as justice, and equity. Nevertheless, the various associated ambiguities and inconsistencies need not be solely considered as a source of weakness, and several educators have identified in sustainability a singular opportunity to analyse and negotiate competing knowledge claims, from different academic disciplines, and thereby stimulate critical thinking and effective learning [13, 14]. Approaching sustainability in a non-prescriptive manner is not just a pedagogical imperative but should be considered integral to architectural design and education. The challenge lies not so much in an illusory pursuit of agreement upon precise goals but in the ability to appreciate „situationally specific‟ contexts and embrace multiple interpretations of a sustainable architecture informed by place and a sense of history [15]. Nevertheless, both teachers and students are faced with the task of negotiating a clear path that embraces robust, yet pluralist, conceptions of sustainability. In this context, critical thinking is the desired learning process and outcome, whilst avoiding the self-defeating trap that sustainability becomes whatever one considers it to be. [16]

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4. THE PROBLEM OF INTEGRATING SUSTAINABILITY ISSUES The ambition of fully integrating environmentally responsible design, and sustainability issues, in the pedagogical progression towards professional practice, is gradually becoming widely recognised within schools of architecture worldwide; but as yet this aspiration remains largely elusive. The heart of the challenge was pinpointed in amongst other literature CEBE‟s 2002 commissioned report of the Sustainability Special Interest Group: “how can we ensure that sustainability knowledge and skills become a natural component of the architect‟s mindset and underpins their value system”? [17]. Of course, this statement begs further questions for tutors concerning how they might effectively explore and negotiate with those values that already inform each student‟s particular understanding of sustainability. The scale of the integration challenge should not be underestimated and research already undertaken gives a salutary warning that official recognition of a university‟s „sustainability teaching credentials‟ is no guarantee that architectural design students will consistently and critically engage with sustainability [18]. One fundamental and well documented impediment concerns the degree of separation that exists between the acquisition of theoretical and technical knowledge, and its creative application in the design studio. Indeed, this may be said to constitute the traditional pedagogical model but it is clearly in tension with a holistic view of architecture and sustainability. Gelernter (1988), drawing upon earlier research into cognitive development, argues that the challenge of “reconciling lectures and studios” has first to confront a curriculum constructed around a misconceived idea of how knowledge is acquired, constructed and applied. In effect, a pedagogical assumption is made whereby students enter a course of learning with a series of „empty folders‟ and that the role of the lecturer is to fill these folders - for example labelled ‟environmental design‟, „tectonics‟, „structures‟, etc - with the requisite information and principles. Having done this, the lecturer carefully places the „filled file‟ in the student‟s virtual filing cabinet for him or her to retrieve later, for example, when grappling with a design problem in the studio. This model of learning makes the highly questionable assumption that knowledge is acquired and applied sequentially; consequently, “knowledge [is being] offered in advance of any attempt to apply it [and so] cannot find a conceptual schema [or model of relationships] in the student‟s mind in which to reside” [19]. Students are consequently left floundering when a design problem is not matched by their first attempt to retrieve a solution from the „filing cabinet‟. Furthermore, this model of teaching and learning misses a vital opportunity to open a dialogue with student preconceptions which inform, or perhaps misinform, their initial approaches to design problems [20]. In contrast, Levy‟s ideas for „Total Studio‟ (1980) [21] – where the design studio is conceived as an

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ideal model for fusing technical and creative design knowledge and practice - have strongly influenced curricula structure paradigms in schools of architecture [22]. Clearly this model meets with substantive limitations beyond the obvious tutorstudent ratio and it should not be assumed that studio tutors are willing or equipped to facilitate the integration of sustainability in architectural design. On the other hand, it is recognised that design studio tutors have indeed the capacity to assume the role of „hegemonic overlord‟ and thus could inhibit – or, at least, strongly influence - the independent and creative faculties of the student according to their own pedagogical agenda [23]. Looking briefly beyond pedagogical models, an engagement with sustainability is also bound to fail if user well-being and quality of design is in any way compromised or diluted in pursuit of essential, environmental aims. Hence, students, teachers and professionals have the responsibility of striving to balance technical skills and environmental responsibility and integrate these within a creative design discourse [24].

5. EDUCATING BEYOND DISCIPLINES Recent years have witnessed a growing body of advocates for a multi/inter/trans-disciplinary approach which, it is argued, is most appropriate and conducive to meeting the challenge of educating for sustainability. It is equally evident that despite the many persuasive arguments put forward, various institutional, cultural and attitudinal impediments remain. Consequently, there is a palpable mismatch between the level of interest in the relationship between multi/inter/trans-interdisciplinarity and sustainability in research and the degree to which this truly informs pedagogy. The case for designing an integrative framework which transcends disciplinary boundaries is sometimes articulated within a discourse characterised by ambiguities and a lack of precision. This is worthy of note, not least because the assumption that overcoming disciplinary domains confers a sense of innovation and the undertaking of cutting-edge teaching and research has induced a tendency to make exaggerated or over-ambitious claims for the extent to which disciplines have actually been crossed or conjoined [25]. It seems helpful, therefore, briefly to offer clarification of some of the terminology, with reference to three of the typologies - deployed by those developing curriculum initiatives – that aim better to integrate approaches to sustainability issues in schools of architecture. The most common form of teaching and learning beyond disciplines may be considered as multidisciplinary, where participants work in parallel to, or sequentially from, disciplinary-specific bases to engage with common problems [26]. However, some commentators regard such endeavours with caution, viewing multi-disciplinary approaches as “additive” rather than genuinely “integrative” as participants remain ensconced within their traditional domains of knowledge [27].

More ambitious in scope but certainly less typical, despite rhetoric suggesting the contrary, are interdisciplinary approaches whereby participants work from a shared perspective that transcends discipline boundaries. In one particularly creative interpretation of distinctions, inter-disciplinarity is made analogous to a kaleidoscope in which components of a picture, or perhaps, even, approaches to specific educational domain such as environmental design, are shaken and stirred beyond individual recognition [28]. Finally, it is worth considering trans-disciplinarity, in which knowledge is generated by participants working together from a shared conceptual framework; ultimately, their interactions hold out the possibilities of producing a new paradigm [29]. More research is needed in order to consider fully how viable such pedagogical approaches are in the context of schools of architecture. Educating for sustainability has undoubtedly raised profound questions concerning how knowledge is acquired and applied and the limits to discipline-based pedagogies. Indeed, this central concept, with its underlying social economic and ecological dimensions, has been considered too complex to be accommodated by „disciplinary reduction‟ [30]. By contrast, it is argued that multi/inter/trans-disciplinary studies have the capacity to bring much needed intellectual synergies, so vital in addressing „future-oriented‟ but profoundly contested goals, and thus confound traditional knowledge hoarding by experts which stifles innovation [31]. However, it would be wrong and counter-productive to underestimate the challenge of restructuring curricula and pedagogy around multi/inter/trans-disciplinarity. Tutors may feel protective of what they consider to be the integrity of traditional disciplines and not easily be convinced that the contestable and imprecise goals of sustainability are compatible with maintaining requisite technical rigour [32]. More often than not, tutors lack experience of work beyond disciplinary boundaries and so not surprisingly anticipate the journey across disciplinary divides with apprehension and possibly mistrust. It may be argued, therefore, that tutors - but also administrators, particularly course directors - have a vital, ethical role to play in championing pedagogical initiatives within their universities, so as to communicate sustainability issues to students within multi/inter/trans-disciplinary structures [33, 34].

6. PEDAGOGICAL OPPORTUNITIES AND CHALLENGES It has been frequently argued that educating for sustainability affords rich opportunities, in theory at least, for profoundly re-designing curriculum structures and introducing initiatives that orientate teaching and learning towards collaborative, experiential and problem-solving activities, whilst simultaneously stimulating critical thinking and deep reflection. Also, designing for sustainability holds out the intriguing possibility of challenging the traditional privileging of „product‟ by elevating the importance of

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„process‟, which should be attributed equal importance within the design studio. Such an approach has the potential to give students greater control over design decisions and thus rejuvenate their critical faculties [35]. Further scope is offered by other initiatives calling into question the traditional architectural pedagogy, with its technical-creative fissure. In this sense, the sustainability agenda demands that educational approaches, which transcend disciplinary mindsets, be actively and innovatively pursued. This, in turn, opens the door to „deep learning‟ as a core pedagogical strategy for approaching an education for sustainability. This particular context, with its attendant complexities, is felt to be in alignment with key characteristics of deep learning, such as the elevation of principles and concepts over known facts. In the process, students are encouraged to take active control over the cognitive processes of planning, monitoring problem-solving tasks and evaluating progress. A sustainability education therefore places high-level demands upon the ability to offer holistic insights and strive for coherence from the management and assimilation of disparate information sources [36]. Deep learning strategies therefore hold many possibilities for advancing a rich and meaningful dialogue with sustainability issues, but educators first need to consider carefully how best to gauge and exploit their students‟ prior knowledge and level of commitment in addressing these issues. Ensuring that learning is made personally meaningful and that a variety of teaching and learning styles are addressed, will help address motivation and promote student “agency”, without which “young people are unlikely to pose [the] significant questions”, which effective educating for sustainability demands [37]. As well as considering the design and implementation of particular teaching and learning strategies, effective integration of sustainability requires that attention to be given to ethos and motivation, both of which form potentially challenging barriers to be overcome. 6.1. Ethos Broadly defined, ethos refers to the distinctive set of values and character of an institution (such as a university), group (potentially a school of architecture) or individual [38]. In the context of sustainability, an ethos might draw inspiration from David Orr‟s advocacy of the need to develop “a wellinformed, democratically engaged citizenry” [39]. The holistic, linked-systems nature of sustainability, calling for collaboration and the pooling of skills and knowledge beyond disciplinary boundaries, means that a total overhaul of the curriculum deserves to be given serious consideration; progress in this direction, it is recognised, would require the participation of the entire department or faculty [40]. However, the active collaboration of all needs to be bolstered by careful promotion of sustainability issues researched and undertaken in the form of design projects within schools of architecture.

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Furthermore, it needs to be appreciated that sustainability ought to be embedded within the whole curriculum so that all subjects contribute towards providing a holistic approach to core and urgent questions and solutions. Research has exposed a number of „misconceptions‟ relating to the teaching and learning of sustainability in Higher Education; for example, that it is too broad and abstract to be effectively taught. Such misunderstandings, and perhaps underlying scepticism on the part of some staff, still pose a significant challenge. To this end, universities might need to consider more robust systems of training in sustainability issues - not only for tutors but also administrators - in order to try and enhance the management of positive change [41]. Nevertheless, it is rightly acknowledged that such an endeavour places a great onus, and perhaps over-reliance, upon individual staff dedication; no insignificant matter when the faced with the pressures of increasing student numbers, volume of assessment and government targets for examination success. It is therefore evident that ethical commitment and clear, determined leadership needs to be supported within a robust system of institutional support for the effective integration of sustainability within architectural curricula and pedagogy. 6.2. Motivation As well as considering ethos, researchers and educators interested in basic questions about how and why students learn must consider the role of motivation. Seeking to understand and address motivation is integral to an education for sustainability which places great demands upon critical engagement but also the willingness to reflect upon and challenge values and behaviour. At the most general level of distinction, motivation is usually considered as being either intrinsic or extrinsic and both realms reveal particular pedagogical opportunities and challenges in the context of educating for sustainability. Intrinsic motivation is internally generated and can be related to the need to fulfil an interest [42]. It can originate from a challenge, a determination to succeed in a task or, conversely, a fear of failing it [43]. In relation to teaching and learning styles, intrinsic motivation aligns with a desire for autonomy, involvement in and a degree of control over the learning task and curiosity [44]. Therefore, curriculum initiatives that are designed to promote such strategies as process-oriented design, collaborative, applied, or problem-based learning, are consciously tapping into a student‟s need for fulfilment and facilitating the development of vital, critical skills underpinning lifelong learning. However, it can be argued that these approaches make certain assumptions upon the level of maturity and time-management abilities necessary for successful student-centred-learning [45]. It is further argued that intrinsically motivated students are more likely to engage in deep learning as they seek to understand the reasoning and principles underlying their study. Whilst this bodes well for critical engagement with sustainability issues,

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it needs to be questioned to what extent summative assessment within university curricula actually reward deep learning and a student‟s selfdetermination [46]. In contrast, extrinsically motivated students are motivated by a need for recognition, praise, or reward; for example that which accompanies grade attainment. Such motivation, usually linked with „surface learning‟ an „performance goals‟, is inevitably a powerful driver in a competitive environment and society, but understanding this could perhaps inspire a reassessment in how best to reward robust participation in learning tasks and projects; for example those engaging with sustainable design, not just in terms of „products‟ but equally underlying processes. Providing constructive, individually targeted and timely feedback may also be considered an aspect of extrinsic motivation [47]. In view of the high student-tutor ratio and everincreasing diversity of assessment, this observation makes a clear link to the commitment of individual educators and the need for solid support systems from the institution concerned. Finally, external factors for motivation can be related to culture and context. There is strong research support demonstrating that individuals are powerfully influenced by their immediate peers, as well as their tutors, and seek to adapt behaviour in order to fit in [48]. In theory, peer groups can be harnessed to articulate debate, review learning and even to reinforce attitudes conducive to sustainable values and lifestyles. Conversely, research can be found to suggest that the culture of the design studio, with its emphasis upon crits, can have a disproportionately negative impact upon the motivation of some students, increasing their sense of vulnerability and alienation [49]. Effective education for sustainability must strive to be as participatory and inclusive as possible. It is therefore imperative that the curriculum, institution and individual educators actively contribute towards a positive ethos that seeks to maximise motivation.

7. CONCLUSION This paper has argued that further research is needed into designing pedagogies which can more consciously and effectively integrate sustainability issues within architectural curricula. Indeed, this paper should be considered as part of an on-going work in the early stages of a 3 year PhD project. Many valuable curricula interventions and multi/inter/trans-disciplinary sustainable design projects have been undertaken to attain this goal but it is clear that they meet with significant challenges along a number of fronts. The complex, conceptually slippery, nature of sustainability is simultaneously a challenge and an opportunity. It demands critical engagement but pedagogical approaches and curriculum developments must be grounded in non-prescriptive, pluralist understandings of sustainability issues that are culture and context sensitive.

The integration of sustainability into architecture curricula must continue to explore and critique ways of narrowing the gap between the technical and creative domains. Solutions seem bound to challenge the traditional lecture structure in order to allow knowledge acquisition and application to become more closely synchronised. New pedagogical approaches also need to navigate tensions arising between the reality of studio tutor power and the goals of enhancing autonomy and decision-making which ought to accompany any orientation toward process-focused, student-centred learning. It is also clear that current research into educating for sustainability forces educators to confront the traditional compartmentalisation of knowledge within disciplines and calls out for multi/inter- and potentially trans-disciplinary teaching and learning. This has the potential to stimulate greater creativity and offer a holistic pedagogy more conducive to tackling not just the environmental but also the social and economic dimensions of a sustainability education. Finally, the task of embedding sustainability within architecture curricula needs to be supported by a determined institutional ethos and continuously review how the commitment and motivation of all involved in the educational process can be enhanced and positively channelled.

8. REFERENCES [1] UNESCO (2010) Education for Sustainable Development, [Online], Available: http://www.unesco.org/en/esd/ [2] Fowles, B., Cocoran, M., Erdel-Jan, L., Iball, H., Roaf, S.,Stevenson, F.(2003), CEBE SIG Report - Sustainable Design in Architecture. Centre for Education in the Built Environment, Cardiff University, pp.1-55, [Online], Available: http://www.cebe.ltsn.ac.uk. [3] Schön, D. (1991), The reflective practitioner: how professionals think in action, 2nd ed. Aldershot: Ashgate. [4] Altomonte, S. (2009), Environmental Education for Sustainable Architecture, Review of European Studies, 1 (2). [5] EDUCATE (2010), Environmental Design in University Curricula and Architectural Training in Europe, IEE Programme, [Online] Available: http://www.educate-sustainability.eu [6] Fletcher, K. & Dewberry, E. (2002), Demi: a case study in design for sustainability, Int. Journal of Sustainability in Higher Education, 3 (1), 38-47. [7] Schön, D. (1991), op. cit. [8] Rutherford, P. and Wilson, R. (2006), Educating environmental awareness: creativity in integrated environmental design teaching, Proceedings of the 40th annual conference of the Architectural Science Association ANZAScA, Adelaide School of Architecture.

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[9] Guy, S. and Farmer, G. (2001), Reinterpreting sustainable architecture: the place of technology, Journal of Architectural Education, 54 (3), 140-148. [10] Wals, A. and Jickling, B. (2002), “Sustainability” in higher education: from doublethink and newspeak to critical thinking and meaningful learning, Int. Journal of Sustainability in Higher Education, 3 (3), 221-232. [11] Dale, A. and Newman, L. (2005), Sustainability development, education and literacy, Int. Journal of Sustainability in Higher Education, 6 (4), 351362. [12] de Eyto, A., McMahon, M., Hadfield, M. and Hutchings, M. (2008), Strategies for developing sustainable design practice for students and SME professionals, Special EJEE Issue on SD in Engineering Education. [13] Wals, A. and Jickling, B. (2002), op. cit. [14] Warburton, K. (2003), Deep learning and education for sustainability, Int. Journal of Sustainability in Higher Education, 4 (1), 44-56. [15] Guy, S. and Moore, S. (2007), Sustainable architecture and the pluralist imagination, Journal of Architectural Education, 60 (4), 15-23. [16] Corcoran, P. and Wals, A. (2004), Higher Education and the Challenge of Sustainability: Problematics, Problems and Practice, Hingham, Kluwer Academic Publishers. [17] Fowles, B. et al (2003), op. cit. [18] Mackie, M. and Kagawa, F. (2007), Opportunities and challenges for students and tutors integrating sustainability into design studio teaching, Proc. Built Environment Education Conference. [19] Gelernter, M. (1988), Reconciling Lectures and Studios, Journal of Architectural Education, 41 (2), 46-52. [20] Rutherford, P. and Wilson, R. (2006), op. cit. [21] Levy A. (1980), Total Studio, Journal of Architectural Education, 34 (2), 29-32. [22] EDUCATE (2010), op. cit. [23] Roberts, A. and Yoell, H. (2009), Reflectors, converts and the disengaged: a study of undergraduate architecture students‟ perceptions of undertaking learning journals, Education in the Built Environment, 4 (2), 74-93. [24] Graham, P. (2003), Building Ecology: First Principles for a Sustainable Built Environment, Oxford, Blackwell. [25] Klein, J. (1990), Interdisciplinarity: History, Theory and Practice, Detroit: University Press. [26] Mitchell, P. (2005), What's in a name? Multidisciplinary, interdisciplinary, and transdisciplinary, Journal of Professional Nursing, 21 (6), 332-334. [27] Klein, J. (1990), op. cit. [28] Wood, G. (2010), Problems Don‟t Come in Disciplines [lecture], Innovation in Built Environment Education conference, Sheffield. 6

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[29] Mitchell, P. (2005), op. cit. [30] Shmidt, J. (2008), Towards a philosophy of interdisciplinarity – an attempt to provide a classification and clarification, Poiesis Praxis, Springer, 5, 53-69. [31] Chapman, D. (2009), Knowing our places? Contexts and edges in integrating disciplines in built environment education, Education in the Built Environment, 4 (2), 9-28. [32] Fenner, A., Ainger, C., Cruickshank, H, and Guthrie, P. (2005), Embedding sustainable development at Cambridge University Engineering Dep., Int. Journal of Sustainability in Higher Education, 6 (3), 229-241. [33] Smith, R. (2009), Guidelines for the Design of a „Sustainable‟ Curriculum in Architecture and Architectural Engineering, MEng Disseration, University of Nottingham. [34] EDUCATE (2010), op. cit. [35] Salama, A., (2005), A Process Oriented Design Pedagogy: KFUPM Sophomore Studio, CEBE Transactions, 2 (2), Sept 2005, pp 16-31. [36] Warburton (2003), op. cit. [37] Greene, M. in Darder, A., Baltodano, M., and Torres, R. (eds.) (2003), The Critical Pedagogy, London: Routledge. [38] Smith, R. (2009), op. cit. [39] Orr, D. (2003), Four Challenges of Sustainability, [Online]. Available: http://www.uwstout.edu/profed/sustainability/upl oad/4CofS.pdf [40] Wright, J. (2003), Introducing sustainability into the architectural curriculum in the United States, Int. Journal of Sustainability in Higher Education, 4, (4), 100-105. [41] Leal Filho, W. (2000), Dealing with misconceptions on the concept of sustainability, Int. Journal of Sustainability in Higher Education, 1 (1), 9-19. [42] Savage, N. and Birch, R. (2008), An evaluation of motivation in engineering students, employing self-determination theory, Innovation, Good Practice and Research in Engineering Education, EE2008. [43] Smith, R. (2009), op. cit. [44] EDUCATE (2010), op. cit. [45] Douvlou, E. (2006), Effective teaching and learning: integrating problem-based learning in the teaching and learning of sustainable design, CEBE Transactions 3 (2), 22-37. [46] Savage, N. and Birch, R. (2008), op. cit. [47] Skinner, B.F. (1953), Science and Human Behaviour, New York: Macmillon. [48] Harris, J. (1998), The Nurture Assumption, London: Bloomsbury Publishing Plc. [49] Datta, A. (2007), Gender and Learning in the Design Studio, Journal of Education in the Built Environment, 2 (2), 21-35.

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Teaching Vernacular Architecture and Rehabilitation in Relation to Bioclimatic Design Elements Maria PHILOKYPROU Department of Architecture, University of Cyprus, Nicosia, Cyprus ABSTRACT: Traditional settlements are by definition sustainable in relation to their environmental context and available resources. The study and detailed investigation of the vernacular architecture of Cyprus and its rehabilitation with special reference to its individual bioclimatic elements, constitute the main subject of an undergraduate course in the Department of Architecture at the University of Cyprus. Students are trained to realize the consciousness of the environmental behaviour of vernacular architecture and to identify the different factors and parameters that contribute to a pleasant environment and thermal comfort within the buildings and their surroundings, through the exploration of different parameters (traditional strategies for heating, shading and ventilation). Theoretical teaching approaches as well as practical ones including in situ observations and investigation of selected traditional settlements are incorporated. Theory and design practice are combined and critical thinking and research skills are developed. Taking into consideration the sustainability of vernacular architecture, the students acquire the skills for environmentally-friendly approaches to the built environment, which will benefit society as a whole. Keywords: sustainability, energy, thermal comfort, environment, vernacular

1. INTRODUCTION The traditional settlements have always constituted an important part of the cultural heritage of every country and are by definition sustainable in relation to their environmental context and available resources (local materials, minimum waste of resources). They are harmonized with their surroundings, respond to the actual needs of people and incorporate many features friendly to the environment (structure, forms, layout). In addition to the historical, aesthetic and social value, the environmental value and particularly the sustainability of these settlements are of utmost importance. Vernacular architecture is a fundamental expression of the culture of a community, of its relationship with its territory and the world’s cultural diversity. Traditional settlements are examples of unique urban setting and architectural creation, incorporating many bioclimatic elements. Their essence depends not only on the fabric of buildings, structures and spaces, but also on the ways in which they were used and appreciated, as they create pleasant environmental and comfortable living conditions (Icomos Charter on the built Vernacular heritage -1999). The previous romanticised attitude towards the study of vernacular architecture that considered only its aesthetic and morphological values have recently changed dramatically. Vernacular architecture is now being appreciated in regard to its environmental principles, structural and bioclimatic values. In this way, its study is useful for new designs and applications [1]. Vernacular architecture is not studied any more as an historic document, but as a model for sustainable design [2] and as a

contribution to new methods, solutions and achievements for the future built environments [3]. In addition, the rehabilitation of vernacular buildings constitutes by itself an important sustainable attitude towards the existing built environment as this incorporates the conservation of non-renewable sources. It is thus obvious that the study and the conservation of such traditional settlements are essential in architectural education. The study and detailed investigation of vernacular settlements of Cyprus with special reference to their individual bioclimatic elements and the identification of the factors that contribute to a pleasant environment and thermal comfort within the buildings and their surroundings, are included in an undergraduate course in the Department of Architecture at the University of Cyprus. Cyprus offers an excellent case for the study and analysis of vernacular architecture as it is a small island which incorporates many different types of dwellings and numerous features. It has mountainous as well as plains and coastal areas with a variety in forms of dwellings in relation to date, layout, materials and construction methods. The typology often changes within a short distance in relation to the immediate environment depending also on the materials availability [4,5].

2. THE AIMS OF THE PAPER In this paper there will be an effort to demonstrate how teaching vernacular architecture and its conservation helps the students create a bioclimatic attitude towards the built environment, as through its study, they learn how man and environment interact, and also how the previous builders had incorporated bioclimatic elements into their designs very successfully. Additionally, in this paper, the creation

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of a critical attitude in the students with regard to the evaluation and the methods of rehabilitation of vernacular architecture will be demonstrated. All of the above will be presented through the description of an undergraduate course on analysis and rehabilitation of vernacular architecture.

3. THE COURSE 3.1. Objectives of the course One of the main objectives of teaching vernacular architecture is to provide the undergraduate students of architecture with basic knowledge and efficient tools to understand, analyse and appreciate any vernacular building or settlement and recognize all the bioclimatic elements and the sustainable behaviour of these buildings. The students are assisted in acquiring skills for the study of the various parameters of vernacular buildings (existing fabric and layout) which improve their energy efficiency. They are helped to understand how man and environment interact, and the consciousness of the environmental behaviour of the vernacular architecture. The students are guided in learning to respect vernacular architecture and the sustainable development of the settlements, identifying the factors that contribute to a pleasant environment and thermal comfort within the buildings and their surroundings. Teaching vernacular architecture aims at acquiring a scientific methodology strongly linked to the study and critical analysis of traditional buildings. Teaching of this subject also aims to stimulate consciousness of the potential conservation and reuse of the existing buildings as a component of incorporating sustainability in architectural education. Another motivation concerns the assignment of general knowledge on certain technical aspects of the intervention so as to maintain and enhance the existing bioclimatic elements - appropriate materials, construction methods, techniques and design principles (architectural and typological data). This investigation helps students to find new sustainable solutions which would also be applicable to contemporary structures – a new field of investigation, under the umbrella of the recently established attitude for environmentally friendly buildings. Therefore, students create new architectural approaches for the rehabilitation of traditional buildings, respecting the bioclimatic elements of existing structures which would also be applicable to new structures. The overall objective of this course is to teach the students new approaches and knowledge skills which will contribute to the sustainable development of the urban environment, "encouraging the sustainable use of resources and strengthening synergies between environmental protection and development” (National Reform Program for Lisbon). 3.2. The interdisciplinary approach and the necessity of the course The study of the bioclimatic elements of vernacular architecture and their preservation

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requires an interdisciplinary approach to problem solving, including knowledge of technology, materials and construction methods. Theory, analysis and creative design practice are combined and critical thinking and research skills are developed. Teaching a methodology of evaluation and rehabilitation of vernacular architecture is important today as many countries like Cyprus are characterized by the presence of an incredible number of vernacular settlements, landscapes and sites that constitute an important part of the cultural heritage. These potential assets for the future sustainable development of the built environment have made the study of these settlements a necessity. It is worth mentioning that in a society which aspires to be sustainable, the efficient use and reuse of built resources becomes a stronger reality as time goes on. Sustainable development is very important in the field of architecture in general. Sustainability and heritage conservation are closely linked together as conservation incorporates the preservation of non-renewable resources. In addition, studies and interventions in the field of restoration of traditional buildings until very recently have taken into consideration parameters referring mainly to the enhancement of the aesthetic values of traditional architecture and the maintenance of the morphological unity. Bioclimatic design principles and elements, although generally appreciated as basic characteristics of the island’s traditional architecture, have not as yet been exploited enough, with negative results to the energy efficiency of the restored vernacular buildings. This attitude leads to direct dependence of buildings on standard industrial air conditioning and heating systems, with disastrous environmental consequences. Through this course the students’ knowledge of sustainability and environmental friendly approaches will be reinforced and society as a whole will benefit. 3.3. Description of the course In this course, an in depth study on the typological and construction elements of the vernacular buildings and settlements is carried out through theoretical teaching approaches as well as practical ones with emphasis on the bioclimatic elements including in situ observations and investigation (surveying, historic and in situ investigation, recording, documentation, research). In addition to the analytical approaches, the course also covers synthetic and creative matters, methodologies of evaluation and rehabilitation of the vernacular settlements, principles of conservation and design intervention with special emphasis on matters of sustainability. Teaching Vernacular Architecture and Rehabilitation includes many different subjects that can be divided into two thematic areas (fig. 1):  Basic knowledge concerning the existing vernacular buildings as well as urban traditional areas of Cyprus (historic, social, urban development, morphology, construction,

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

typological analysis with special reference to their bioclimatic elements). Elements of theory of conservation and rehabilitation as well as technical and methodological aspects concerning structural problems aiming to preserve and reinforce the bioclimatic elements.

ventilation of the house. The central courtyard has its roots in prehistoric and historic periods of antiquity in Cyprus and other Mediterranean countries due to their hot dry climate.

Figure 1. Diagram of the structure of the course

3.3.1. Analysis of vernacular architecture The close investigation of vernacular architecture covers the exploration of different parameters such as:  Arrangement and combination of closed and semi-open spaces around a central yard, their orientation and their inter-relations and communications.  Relationship of buildings to their immediate built or natural environment (moisture, temperature, location in the urban core -nucleus, proximity to other buildings).  Type, material and quality of the shell (wall and roof construction, natural insulation, use of color, mass, impermeability) as well as possible storage elements of energy (mass, etc.).  Traditional strategies for heating and shading (sun penetration, adjustable elements, planting deciduous trees, shading devices, pergolas, etc.).  Traditional strategies for ventilation and cooling (sizes/dimensions, orientation, arrangement and location of openings, air movement, ventilation, multiple openings, cooling by upper evaporation). More specifically, the arrangement and orientation of the rooms around a central yard is very carefully studied in this course as this constitutes a very important bioclimatic element of the vernacular layout. This outside space (yard) creates a perfect microclimate for the house, serving the inter-relations and communications between separate rooms (fig. 2). It is the central and dominant feature of the dwelling and at the same time an intermediate buffer space between public streets and private rooms. Volumes are arranged around the yard in such a way as to create shadow, which improves the cooling and

Figure 2. The central yard (students’ work).

Special reference is given to the semi-open spaces (illiakoi, porches, galleries) very often arranged in front of the south side of the building in close relation with the yard [6,7] . They serve as a connection passage of the house giving at the same time shadow and protection of the facade and the openings from the direct rays of the sun. They offer a comfortable intermediate living space for mild and hot days.

Figure 3. Relationship between buildings and street (students’ work)

The way the traditional buildings are successfully integrated into their immediate environment is also studied in this course. They are closely built with common walls, thus protecting the external wall surfaces from direct sun rays. In mountainous areas

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a vertical layout is created where very often the top of a house serves as a veranda for the level above. Thus, nature, climate and topography are important parameters that play a significant role in the design. Streets are very narrow surrounded by one or two storey dwellings that offer shading to the passage way (fig. 3).

acting as shading devices in the hot summer, keeping rain water from walls and windows during winter (fig. 4). Shading and ventilation constitute two very important parameters that are investigated in detail in many different stages of the course. Shading of the houses and especially of the south walls is achieved through plantation of deciduous trees and scafoldings supporting deciduous vines. Thus plantation is used as a sunshine moderating factor preventing direct sunshine rays during summer and admitting sunlight in winter (fig. 5). The main facade of the dwellings is oriented towards the south, whereas the north facade is usually opaque and completely closed. Ventilation is mainly achieved through the various openings of the houses and especially through their cross arrangement. They are sized and placed proportionally in order to allow the required amount of light and air circulation and to provide comfort. Windows are often minimized to be consistent with interior requirements. Smaller openings (arseres) located above these windows (just below the roof) serve for ventilation purposes, allowing the warm air to escape and at the same time providing daylight to the maximum depth possible and serving ventilation needs when the house is not occupied.

Figure 5. Shading with deciduous trees (students’s work)

3.3.2. Rehabilitation principles Figure 4. Building materials (students’s work)

A special issue of the course is the study of the thermal insulation of the buildings which is achieved by using materials with a high thermal transfer coefficient and with good thermal inertia (fig. 4). The walls are built of stone or mud bricks or a combination of the two, depending on the region. For ceilings and roofs, thermal insulation is provided by successive layers of clay, twigs and straw laid at the top of the main beams. Small roof overhangs are

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Another very important part of the theoretical teaching is the analysis of the different charters and declarations concerning conservation involving the great diversity of values of vernacular architecture. Through the study of these charters, issues concerning integration of missing parts, elimination of additions, compatibility, retreatibility and reversibility of materials and structures are covered. These principles include the idea of sustainability as they enable future treatments to be carried out based on

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

new scientific knowledge. It is well known that any treatment to an existing structure is not likely to be the last. This course does not try to impose a particular view on the students, but rather to develop habits of critical thinking. 3.3.3. Practical project In parallel with the theoretical teaching, a practical project divided into an analytical and a synthetic part is carried out. In the first part of the project students are dealing with a selected traditional settlement, followed by an analytical study of a chosen building or group of buildings. This project includes urban as well as typological, morphological and structural analysis of the traditional settlements and the dwellings (types of houses and rural layouts - detached system, arrangement around the central yard, orientations, inter-relations, communications, materials etc.) with emphasis on the bioclimatic elements. Additionally, the daily habits of the residents are recorded in order to investigate how these habits contribute to the creation of appropriate living conditions (opening windows during the night, closing of them during noon etc.). Survey methods and architectural analysis are applied to a real case-study. The in situ visits and observations of real buildings help the students to acquire a personal experience of the vernacular settlements and the internal climatic conditions of old buildings and feel with their own senses the living conditions and comfort resulting from the use of appropriate building materials and forms.

in a resourceful and responsible way respecting the environment and climate of each region. Through the surveying of vernacular buildings, students will acquire the practical architectural skills for site analysis (measuring, observing, sketching etc.) that are essential for their studies and their future professional practice (fig. 6). The survey and detailed analysis is followed by the second part of the project that includes graphic proposals for the reuse of vernacular buildings using contemporary and traditional methods. The students are invited to recover and refurbish the traditional buildings and to explore small architectural design proposals inside and outside the existing fabric and to choose materials and techniques autonomously in order to preserve and reinforce their bioclimatic elements. This part of the project includes detailed architectural drawings as well as 3D graphic models (fig. 7). Students develop the first part of the project (analysis) on an individual basis and their design projects on a team basis and have weekly microstudio criticisms.

Figure 7. Students’ design intervention proposals

Figure 6. Students’ sketches of traditional buildings

Thus, the students can realize how comfortable the traditional space is. They are encouraged to feel the interaction between people and buildings and how the buildings serve people’s needs using simple methods and tools. This deep understanding helps students initiate rehabilitation and design decisions

Working on a specific traditional building, the students are invited to develop their personal choices of intervention, using mainly new materials with proper structural behaviour which are compatible with the authentic ones. The design interventions incorporated are developed through a holistic approach, taking into serious consideration all the values of the buildings and especially the bioclimatic elements of vernacular architecture (fig. 4). Therefore, students create new architectural approaches for the rehabilitation of traditional buildings which would also be applicable to new contemporary structures, converging with the solutions reached by traditional architecture through centuries of trials and errors far away from picturesque or historic conservative approaches. As vernacular architecture does not rely on high-tech energy consuming systems for heating, cooling and ventilation, the students are encouraged to think about passive sustainable systems in design projects. The combination of theoretical teaching, assignments and projects is a pedagogical approach and an implemented educational strategy which leads to an overall knowledge of the subject and to the acquisition of essential practical tools. The theoretical and practical parts of the course are

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developed simultaneously. Thus, in situ building surveys, analytical studies and design interventions run parallel to the theoretical lessons. Through this course, the students will develop skills regarding bioclimatic and other important elements of vernacular architecture, acquiring a holistic understanding of the existing built environment.

skills and competencies for participation and action [9]. A systematic knowledge of traditional architecture and building technologies is the basis for supporting stable, balanced and sustainable socioeconomic development and promoting conservation and rehabilitation of vernacular architecture. A deep and meaningful engagement with vernacular architecture and the rehabilitation process can inspire creative designs that sustain the productive life of the existing environment. If all the undergraduate students in architecture schools become familiar with vernacular architecture and its bioclimatic elements, they will be ready to develop an attitude of sustainability towards the environment.

5. REFERENCES

Figure 8. Sketches of students’ surveying

The results of the analytical and synthetic parts of the projects show that the students acquire the essential skills for documentation, recording (fig. 8 and fig. 9) and analysis of vernacular architecture, recognising and preserving its bioclimatic elements and incorporating them during their design interventions.

Figure 9. Construction details (students’ work)

4. CONCLUSION Many architects have today turned to traditional architecture for answers even to modern problems, observing its forms, and use, analysing its rules and patterns and studying its physical and social structure. Good architecture understands the past, rescues still-standing values and combines these values with contemporary techniques that allow the development of an energy efficient up-to-date architecture [8]. Thus, the importance of vernacular architecture does not lie on its study as a past tradition, but as a contribution to new methods, solutions and achievements for the future built environment. Architectural education today focuses not only on the buildings themselves, but also on more complex social issues, such as links between environmental quality and human equality, requiring a new pedagogy which sees students developing

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[1] A. Rapport, Vernacular Design as a Model System in Vernacular Architecture in the Twenty-First Century: Theory Education and Practice, ed. by L. Asquith and M. Vellinga (2006). [2] A. Heal, C. Paradise and W. Forster, The Vernacular as a Model for Sustainable Design, Proc. 23th Conference on Passive and Low Energy Architecture, Geneva – Switzerland (2006). [3] L. Asquith and M. Vellinga, Introduction, Vernacular Architecture in the Twenty-First Century: Theory Education and Practice (2006) [4] Sinos, S., A Review of the Vernacular Architecture of Cyprus. Athens (1976). [5] Ionas, J., La Maisone Rurale de Chypre. (XVIIXXe siècle). Aspects et Techniques de Consturction, Νicosie Publications of the Science Research Centre. Nicosia. Cyprus (1988) [6] Papacharalambous, G., The Cypriot Dwelling. Publications of the Cyprus Research Center II. Nicosia (1968). [7] Sinos, S. Types of Rural Dwellings in Cyprus”, in Acts of the International Archaeological Symposium “Cyprus Between the Orient and the Occident”, Nicosia, 8-14 September 1985, pp. 520-533. [8] C. Ganem, A. Esteves and H. Coch, Traditional climate-adapted typologies as a base for a new contemporary architectural approach, Proc. 23th Conference on Passive and Low Energy Architecture, Geneva – Switzerland (2006). [9] C. S. Hayles and S. E. Holdsworth, Curriculum Change for Sustainability, Journal for Education in the Built Environment, Vol.3, Issue 1, July 2008, 25-48.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Cooperative Design in a Postgraduate Distance Learning Scheme in Brazil: A case study on a more sustainable low-cost housing proposal M. A. SATTLER 1

1

, L. M. S. ANDRADE2, R. R. M. P. BARROS3, G. S. TENORIO2

Federal University of Rio Grande do Sul-UFRGS, Porto Alegre, Brasil, e-mail: [email protected] 2 University of Brasilia-UnB, Brasilia, Brasil, e-mail: [email protected]; [email protected] 3 State University of Campinas-UNICAMP, Campinas, Brasil, e-mail: [email protected]

ABSTRACT: This paper describes a successful experience on distance learning in a postgraduate course in architectural and urban environment rehabilitation, as required by the urgent need to work on education in sustainability, in a larger scale and counting on contemporary non-conventional approaches. Students from five geographical regions all over Brazil, with a range of cultural and climatic characteristics, were organized into groups and asked to consider the specificities of their local realities, when presenting solutions for a low-cost more sustainable housing project. The design was to be based on eco-construction techniques, permaculture principles, sustainability strategies and humanizing concepts. The interaction between students was mainly through discussion forums and chats on the web, and the final product was formatted on a Wiki. The “South group” was one among those that reached a fairly high level of quality, when regarding at the incorporation of sustainability issues. Its work showed a thorough understanding of socioeconomic and environmental constraints, especially in terms of bioclimatic issues. Thus, it was selected to be described in more depth. This paper aims at illustrating how the group applied the design method, showing that distance learning is enabling interesting results also in the area of sustainable architecture and urban planning. Keywords: distance learning, sustainability education, ecological architecture design, eco-construction

1. INTRODUCTION The expressive degeneration of the built environment in recent decades, aligned with the current economic system, has been concerning a growing number of people. It is unquestionable the urgent need for rethinking the human habitat, especially of low-income communities, with models of sustainability consistent with a civilization that has reached its apogee in science and technology, but has given so little attention to systems for preserving life. The awakening of environmental awareness and its implications for the practice of architecture, engineering and related fields has been increasingly valued by Brazilian academic programs. However, due to the country’s continental dimensions and developmental disparities among its geographical regions, opportunities for accessing information and for construction of knowledge are not the same for everyone. Distance education initiatives aim at overcoming this difficulty by bringing students and teachers closer, making possible the exchange of expertise and the building of advances together, both in practical applications and research. Distance learning network tools allow for previously unimaginable levels of interaction, which add not only to those involved in the areas of knowledge construction but, above all, to the field of education in general. The present paper describes the experience of a challenge presented to students of the Diploma Course on Sustainable Architecture and Urban Environment Rehabilitation – shortened as Reabilita

(in Portuguese) - connected to the discipline of Ecoconstructions, one of the Diploma Course modules. This course was created and is hosted by the Laboratory of Sustainability from the School of Architecture and Urban Planning of the University of Brasilia (UnB), with support from the University of São Paulo (USP) and Federal University of Rio Grande do Sul (UFRGS). Its goal is to train professionals, mostly architects, to rehabilitate the architecture and urban structures as well as to convey concepts and values which may be employed even in situations that require the development of new projects. The modules of Reabilita make an attempt to enable students to deal with the various scales of sustainability (from the regional scale down to that of the building), under different approaches (from passive environmental control techniques to recycling and management of derelict sites). The course is structured on the Moodle virtual learning environment (moodle.org) and centers the learning process on the student, stimulating his/her autonomy. Students share experiences, provide contents, discuss, and participate in the growth of the whole group. This interaction is neither mandatory nor scored on evaluations. It is intended to be spontaneous and is stimulated by all who come to realize that this type of construction of knowledge is also an important component of true sustainability. Hence it is a system where a great variety of information is managed, where each one realizes the importance of the parts in the making of a meaningful whole, in which the pleasure of communicating and cooperation is encouraged and where there is no hierarchy in the interaction. Every student manifestation, either positive or negative, about the

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course is recorded. Every manifestation tends to be spontaneous, collaborative and not hierarchical. The challenge proposed to students during the 2009 Eco-construction module was to design a More Sustainable Low-Cost Housing Development that would incorporate a set of more sustainable techniques in the production of the desired built environment. More sustainable is here referred as a little step in the direction of sustainability as we do not believe in achieving something really sustainable in the next generations’ foreseeable future. The aim was of encouraging the development of alternatives for more sustainable human settlements which could, in turn, inspire students and professionals, as well as the public sector, in committing themselves to offering better standards of living for those economically less favoured. The principles for the development of the projects, their elaboration dynamics and the commented results shall be presented here. A final analysis of the process and product close the report. In order to carry out the activity, the students were divided into 9 groups of 8 to 11 people, representing a variety of regions of Brazil: North (2 groups), Northeast, Southeast, South and Midwest (4 groups). For each group an open forum and a chat room were created, which remained available throughout the whole activity. These would be the proper place for exchange and interaction. Furthermore, the students were informed that all discussions would be recorded and could be retrieved later. The groups had the autonomy to choose their chat schedule, to decide about the design location, to prepare all the guidelines and to divide the design tasks among each one of their group components. This division, in most cases, happened almost naturally, and resulted from the emergence of multiple leaderships, arising from the affinity with the subject or from a manual skill or a technical expertise. At the end, all groups got deeply involved in the development of their specific product, understanding the meaning - the group participation in a project of major importance, and the possibility to work with a real life case study (even considering all the limitations involved) where to apply the principles of sustainable design learnt in the module. Making an appraisal of the process, the teachers found the results both revealing and surprising: networks were formed that enabled the groups to achieve their goals. Regarding the products, some proposals reached a high level of design, as far as the incorporation of issues of sustainability are concerned. One of the groups henceforth named “South Group”, as they were from a southern region of Brazil - showed a thorough understanding of socioeconomic and environmental constraints, especially in terms of bioclimatic issues. This is one of the reasons why it was chosen to be presented here in more detail.

2. DESIGN AND EVALUATION CRITERIA The strategies for more sustainable human settlements were previously presented to the students of the discipline Eco-constructions -

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presenting concepts and methods of design and construction. These focused on aspects ranging from the urban to the building scales, such as low environmental impact building materials, bioclimatic design, use of sustainable energy sources, management of household and construction wastes, local food production, sustainable mobility, water management, among others. The innovative proposal of the Eco-construction module was to promote and encourage the students to work cooperatively through a Wiki, on a distance education scheme. The students were then asked to identify an area of about one hectare (10,000 sq.m.) in their own cities. This area should be attractive and appropriate to carry out the activity: providing easy access and availability of information about their social, economic and environmental context, both on digital and graphical form. The area should be designed to accommodate a proposal (at a preliminary study level), for a more sustainable low-cost housing scheme. The potential degenerative impacts which could occur should have to be anticipated and mitigated, and the students should envisage qualifying both the built and the natural environment. 2.1. Guiding principles for the design of more sustainable settlements There is interdependence among environmental challenges, which must be overcome when aiming at a more sustainable world. The major ones lie on the social and environmental spheres and include: the loss of biodiversity; deforestation of areas for growing grains and cattle (many times by fire, which severely increase gas emissions); growing scarcity of fossil fuels, deterioration of hydric resources (in many cases leading to shortage), both in quantity and quality; and the increase of social inequalities. However, when analyzed in the light of the General Systems Theory, it is possible to notice that they are all related to the “form” in which settlements are configured, both in urban and rural areas. Although cities occupy only 2,5% of the Earth´s surface, they consume 75% of all its resources. The way we build places to live shape the way we live [1]. According to the author, "the construction builds", and if the physical structure of the city and his organization are not taken into account, we will not be able to solve all the problems of disintegration of the planet and ecosystems. What is built creates possibilities and limitations to the way we live, at the same time as it educates those who live in the city on true values and real concerns. In order to better understand how to design human settlements in balance with nature, in such a way that is also economically viable and creating pleasant places to live, a study [2] was conducted on how ecological principles can turned into guidelines for building more sustainable communities. The author proposed the use of the principles of environmental sustainability for the design of urban settlements. These principles are based on some authors [3, 4, 5, 6, 7] who suggested the use of the ecosystemic approach to human settlements and cities.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The direct application of ecological sciences in reshaping the foundations of our communities through green projects is a way to overcome the barrier that separates the human ecosystems from the ecologically sustainable systems of nature [3]. The principles of ecological design reflect the principles of organization of nature, such as networks, cycles, solar power, alliances, diversity and dynamic balance. These principles offer a set of guidelines for building more sustainable communities. Sustainable education can be achieved through a planning system aiming at creating more sustainable human environments [8]. This is the goal of permaculture, according to Bill Mollison and David Holmgren, that in the 70s created its foundations, as a methodology for creating productive, sustainable and ecological environments, which enable man to inhabit the Earth without destroying it. Permaculture works with three basic principles: Earthcare, peoplecare and fairshare. This theory is based in the ideal model of sustainable culture: food security, water, energy and technology, communication and culture, ecosystems and local species and economy. Guiding principles for the construction of more sustainable places [9] are proposed in alignment with the following themes: economic and educational issues, urban settlements, energy, construction, materials, food production, water and waste. The design of more sustainable places must also be concerned with the education of people on how to can live more sustainably: how to be more efficient in terms of energy and water consumption and how to use materials with less embodied energy or near zero carbon emissions, such as sustainably managed wood. In addition, the users of such settlements should also learn how to deal with the waste produced, avoiding the reckless dumping of toxic material and composting organic wastes; how to preserve of the natural surrounding environment along with its biodiversity, and on the possibility of producing food on site, in harmony with communal spaces. Deriving from these guidelines, a methodological strategy was proposed for the design of more sustainable places that included: principles of permaculture [4] and eco-construction techniques [9]; environmental sustainability strategies applied to urban design [2]; humanizing concepts within the categories of urbanity and dwelling [10], in line with Christopher Alexander´s patterns [11]. The principles of permaculture [4] and of ecotechniques [9] were organised as follows: -Materials: use of local and non-toxic materials that are culturally accepted and have a small footprint. -Buildings (in and around): use of adequate openings, for ventilation and lighting; fruit trees and deciduous trees, for shading; herbs in and around; areas improving habitability and respect for regional architecture characteristics. -Energy: use of renewable and alternative energy sources, including biodigestion, to produce biogas and fertilizers. -Water: use of rainwater for domestic use, irrigation and toilet flushing; complementary water collection

and retention basins, for irrigation and food production. -Waste: recycling of organic and inorganic wastes; composting; wastewater treatment with the aid of aquaculture ponds; biodigestors; dry toilets; water reuse. -Food: local production; productive landscaping; diversity of cultures; infiltration channels; crop rotation systems; chicken tractors (Permaculture); mulch and trailing plants for soil protection; organic farming; gardening with organic standards. -Site-planning: fitting to the topography; re-use of tires, debris, and stones for the buildings; winding routes (roads and paths) giving priority to pedestrians; permeable paving; intensive use of vegetation, to improve the local climate; organic architecture; adaptation to local climate; zoning of cultures, according to intensity of use. -Socioeconomic issues: nurseries run by communities; community center to suit different activities; open areas, for recreation and social interaction; commercialization of food surpluses and inorganic waste; income generation through in housing work spaces. Principles of environmental sustainability [7] were translated into strategies and techniques for the design process [2]. These are attributes or principles associated with urban morphology that can directly guide the deployment and recovery of urban communities, bringing significant and long-range impacts in the economic development and social and environmental health. The suggested techniques and strategies are as follows: -Environmental protection (biodiversity): environmental assessment and surveying of environmental legislation in the area and law enforcement and recovery plans for watersheds or forests. -Urban Infill: avoiding urban sprawl, to restrain the urban occupation of agricultural land; increasing the sense of community and reducing emissions of carbon dioxide by minimizing commuting. -Urban Regeneration: restoring urban areas in order to increment the use of existing infrastructure; aiming at living cities, attracting new residents, commerce and activities into neighbourhoods in revitalized derelict areas. -Establishment of neighbourhood centers: commerce within walking distances -Local economic development: establishment of l strategies for the development of local economy, -Implementation of sustainable transport: provision of bicycle lanes, made agreeable and confortable by vegetation, interconnected with streets or public transport networks; creation of attractive pedestrian connections and speed bumps;; encouragement to walking or riding bicycles, which promotes the reduction of CO2. Narrowing streets; reduction of impermeable surfaces; -Affordable houses: along with urban design, such as inclusive zoning, density bonuses and money for land, encouraging economic housing; diversity and mixed social standards, with a variety of housing of different costs.

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2.2. Evaluation criteria for the design activity The work was supposed to be accomplished in teams and the team itself should define (and justify!) the chosen design guidelines (or guiding concepts): density, number of dwellings and maximum population, characteristics of the occupation, land use, additional equipment, integration with the environment etc. All the principles above described were to be implemented and would serve as guiding parameters to the assessment of the students’ works. In addition, the evaluation would consider: characterization of the area in various fields: consistent design guidelines; adequacy of the solutions to the context of sustainability and established guidelines; creativity and uniqueness of solutions; and graphic and textual quality of the proposal. The proposals were evaluated with basis on the criteria shown in Table 1.

PROCESS

Table 1: Evaluation criteria for Eco-Construction activities. EVALUATION CRITERIA Participation Analysis

Sustainability principles applied to urban design

PRODUCT

-Communities with a sense of neighbourhood (habitable): providing opportunities for sociability and community facilities -Alternative wastewater treatment and natural drainage: treatment of wastewater with plants (root zones) or wetlands. -Integrated water management: compacting developments; use of roof gardens and permeable parking lots and roads; cisterns, for reuse of rainwater or local treatment of wastewater; -Alternative energy: using energy from renewable sources, such as solar, wind and biomass energy; -Policies based on the 5R's (Reflect, Reduce, Reuse, Recycle, Refuse): including reuse and recycling of buildings and construction wastes. Humanizing concepts [10] incorporate about 65 design parameters and aim at structuring a humanizing knowledge base to support a better fulfilment of an ample spectrum of human needs in multifamily housing. The patterns of Christopher Alexander [11] were translated and interpreted as design parameters in order to emphasize its content and propositional character, especially considering the prescriptive character commonly associated to the term pattern in Portuguese. The concepts require an effective compatibility among the different possibilities individually suggested by the design parameters. The two main categories – Sense of Urbanity and Sense of Dwelling – respectively focused more directly on the territorial arrangement and on the building scale and dwelling units themselves - are considered equally fundamental to design quality as a whole and are here briefly described. The conceptual category Sense of Urbanity aims to provide urban vivacity to settlements that requires avoiding rigid zoning, social segregation and difficulty of locomotion. Other aspect to be considered is the enabling of the perception of a sense of place in tune with the surrounding environment, from the arrangement and articulation of outdoor spaces, which enhances psychological functions of orientation and identification. A sensibility to the existing built and natural environment allied to specific spatial attributes and social sustainability parameters – valuing household mix, diversity of income, mixed use, pedestrian circulation – all contributing to spatial connectivity, legibility and identity. The conceptual category Sense of Dwelling attempts to provide, beyond basic needs of environmental comfort and use, a sense of inhabiting that fulfils the necessities of refuge, isolation, conviviality, order and variety. They focus on the following issues: (1) impact of site planning and units’ joining possibilities to aspects of environmental comfort and privacy; (2) relation between physical structure and social spaces so that form and dimensional proportions of spaces prioritize the fulfilment of varied human needs and not a simplistic constructional rationality; (3) indoor arrangements and transition zones aiming at an efficient, legible and permeable intimacy gradient; (4) character and attributes of natural and artificial lighting, finishing materials and roof; (5) offer of housing options to diverse household types and its implications to construction system, maintenance, adaptability and expansion.

Eco-techniques and permaculture

Humanizing concepts and design parameters (patterns)

ECO-CONSTRUCTION ACTIVITIES 1.Foruns; 2.Chats; 3.Wikis 1.Environmental restraints; 2.Social economical situation; 3.Urban context; 4.Repertoire 1.Environmental protection; 2.Density; 3.Sense of neighbourhood; 4.Urban rehabilitation; 5.Economic development and commercial centers; 6.Natural drainage; 7.Low impact sewage treatment; 8.5Rs Policy; 9.Renewable energy; 10.Integrated water management; 11.Mobility and accessibility; 12.Affordable housing 1.Materials; 2.Housing; 3.Energy; 4.Wastes; 5.Food production; 6.Site-planning; 7.Water; 8.Socio economic and educational issues Sense of Urbanity: 1.Sensibility to the built and natural environments; 2.Connectivity, legibility and social sustainability; 3.Identity Sense of Dwelling: 1.Spatial harmony: relation between environmental comfort and privacy; 2.Sense of home; 3.Options and flexibility

The final submission was expected to be a text collectively built, using the Wiki software (similar to the one used by Wikipedia), where anyone would be able and entitled to edit a regular text. This text should contain the presentation of the target area and its characterization (product analysis and evaluations); illustrations of the target area, descriptive text, illustrated with technical drawings and schematic volumetric perspectives in such a way to allow the proposal to be understood (settlement and housing units). Within a five-week period for the whole module, the students were given three weeks for accomplishing the design assignment. Teachers

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

and project coordinators were aware of time constraints, but believed possible the satisfactory completion of the activity at the end of this period.

3. THE CASE STUDY The Design Proposals for a More Sustainable Low-Cost Housing Development developed by the students were considered as achieving a fairly high standard, with regard to the incorporation of sustainability issues into design. From the nine students groups involved in the challenge, three achieved the expected standard, two were considered as achieving an intermediate level, and the remaining works fell below the expectations. Preceded by a short description of the South Group chosen area, a design analysis summing up the teachers’ evaluations of the design product is presented and followed by their proposal in Figure 1. Located not far from a large rural zone of rice cultivation, the area chosen by the South Group was in the midst of an urbanized neighbourhood named Bairro do Meio, in the city of Joinville, up North in the State of Santa Catarina, South of Brazil, close to a mountain range and not far from the sea. The land has a 10% slope and almost no vegetation. The local climate is characterized by four well-defined seasons, with short dry periods. Temperature ranges from monthly averages of about 26ºC to 19ºC with prevailing winds come from East and Northeast (in summer) and from the South in winter. The teachers’ appraisal of the Groups work was as follows: a) Sustainability principles applied to urban design: Excellent understanding of the socioeconomic and environmental constraints, especially in terms of bioclimatic issues. The only missing topic was the detailing of the environmental impacts of the settlement on the Morro do Meio basin. The area could hold a higher density and the connections with the city could be better established by paths, commercial and service areas (such as the proposed community center), along pedestrian and bicycle paths that surround the area and cross the central axis leading to the housing units. b) Ecotechniques: The chosen materials fit well within the specified region, as well as the strategies for comfort, wastes treatment, recovery and reuse of water and permaculture techniques. The large “convivial central axis” is the community meeting point, the space for enjoyment, meeting, stay. It was provided with green areas with sitting spaces, pergolas supporting shading plants, creepers, flowers and bushes. Sitting areas with playing tables, as well as playgrounds, green areas, kiosks for barbecue making and provided with hammocks, tables for eating in groups, turn this space into the central artery of the settlement, with it vitality derived from meetings, access to dwellings and access to playing areas. Next to the dwellings a vegetable garden was proposed, for every two houses, besides the collective gardening area in the higher plot in the housing settlement. c) Humanizing concepts: Sense of Urbanity: Building improving land with careful consideration of environmental constraints. Good intertwining of building and place and views.

The proposal could be improved with the inclusion of positive external spaces and connected buildings, as well as with increased users’ diversity. Design of the community center is underdeveloped and seems disconnected from the housing units. Sense of Dwelling: Units elevated from the ground enjoy privacy and natural ventilation. Design prioritizes natural light for different rooms and positions; bedrooms to the east. Good intimacy gradient. There is an entrance transition, entrance room and openings’ gradient. The units allow expansion.

Figure 1: South Group design proposal. Design team: E.O. Beck, A.R. Beine, B.M. Guimarães, R.B. Martins, F.K.R. Mingotti, C.C. Rothen, M.C. Scharnik and E.O. Soares.

4. FINAL CONSIDERATIONS This paper describes a successful experience in distance teaching and learning, as far as interpreted by the authors. First, due to the students’ involvement in a rewarding – in their own words – and “sustainable” process of cooperation in the development of their final work. This process enabled them to put into practice what they learned, not only during the module of the Eco-construction discipline, but also during the whole Reabilita Course. The Internet discussion forums, chats and

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even mutual consulting among themselves brought into close contact students, from several different Brazilian regions, some several thousand miles apart ,almost as they where collaborating in the same office. Although some students, mostly those deeply involved in their day-to-day activities and having little time to interact, referred that it was hard to work this way, others felt very motivated and even demonstrated their enthusiasm with the learning and the achieved results. Something similar was also felt on the teachers’ side. The whole team of teachers (authors of this paper), tutors and course coordinators was not sure of what could result from this experience and what would be the students’ response. As far as we know it was the first experience of the kind in Brazil. The whole evolution of the design process was documented, step by step, in a way that enabled assessing each student individually, and not, as is the usual in traditional teaching, where just the final work is presented and assessed. The overall assessment made by the teachers directly involved in the process was that the EcoConstruction module demanded them intensely in the first issue of this experience. It can be said that three stages were clearly distinct: the first, that was the creative step – leading to the conception of the activity and the process itself; the second, by far the most demanding, as it required an almost continuous presence of, at least, one member from the teaching team on the Moodle platform; and the last, requiring the final formatting of the texts associated to the Wikis and those connected to the students tasks assessment. It must be recognized that not all achieved products, the design ideas proposed by the students, for a More Sustainable Low Cost Housing Development, were considered achieving a high standard, mainly with regard to what was the main aim: sustainability issues being incorporated into design. The authors’ evaluation was that, from the nine groups involved in the challenge, three achieved the expected standard, two were considered as achieving an intermediate level, and the remaining works fell below the expectations. The experience, new both to students as to the teachers, should constitute a new reference, at least inside Reabilita Course, towards teaching/learning processes. First, due to its highly inclusive outcome: counting with students from 24 different Brazilian States (out of a total of 26 Brazilian Federative States) and the Federal District, with students as far apart as 5.000 km and that ordinarily would be unable to attend a post-graduate course. Secondly, due to the diversity of sustainability dimensions challenging the participating students: environmental, economical, social, cultural, spatial, among others. The most noticeable advance in teaching and learning was its participatory characteristics in the emerging network. It is understood that the process showed such richness that new studies will be stimulated trying to formulate what, maybe, could lead to a new path to educating in a more sustainable way: An Education in Sustainability in the Areas of Architecture and Urban Planning in the Wikis’ Era.

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5. REFERENCES [1] Register, R. Ecocities, building cities in balance with nature. Berkeley: Berkeley Hills Book, 2002. [2] Andrade, L.M.S. Agenda verde x Agenda marrom: Inexistência de princípios ecológicos para o desenho de assentamentos urbanos. Dissertação (Mestrado) - Faculdade de Arquitetura e Urbanismo da Universidade de Brasília. Brasília, 2005. Available at: [accessed 10 January 2008] [3] Capra, F. As conexões ocultas, ciência para um vida sustentável. São Paulo: Pensamento/Cultrix, 2002. [4] Mollison, B. Introdução à permacultura. Brasília: Fundação Daniel Efraim Dazcal, 1998. [5] Rueda, S. Modelos e indicadores para ciudades más sostenibles. Barcelona: Departament de Medi Ambient de la Generalitat de la Catalunya/Fundació Forum Ambiental, 1999. [6] Rogers, R. and Gumuchdjiam, P. Cidades para um pequeno planeta. Barcelona: Editorial Gustavo Gilli, 2001. [7] Dauncey, G. and Peck, S. 12 features of sustainable community development: social, economic and environmental benefits and two case studies in sustainable community development in Canada. Available at: [accessed 15 October 2009] [8] Legan, L. A Escola Sustentável, ecoalfabetizando pelo ambiente. 2a edição atualizada e revisada - São Paulo, Imprensa Oficial do Estado de São Paulo, Pirenópolis, GO: Ecocentro IPEC, 2007. [9] Sattler, M.A.. Habitações de Baixo Custo mais Sustentáveis: a Casa Alvorada e o Centro Experimental de Tecnologias Habitacionais Sustentáveis. Coleção Habitare/ FINEP. Porto Alegre, 2007. Available at: [accessed 10 January 2008] [10] Barros, R.R.M.P. Habitação coletiva: a inclusão de conceitos humanizadores no processo de projeto. Tese (Doutorado) - Faculdade de Engenharia Civil, Arquitetura e Urbanismo, Universidade Estadual de Campinas, Campinas, 2008. Available at: [accessed 10 March 2009] [11] Alexander, C., Ishikawa, S., Silverstein, M., Jacobson, M.; Fiksdahl-king, I.; Angel, S. A pattern language: towns, buildings, construction. New York: Oxford Univ., 1977.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

NEW OPPORTUNITIES IN TEACHING SUSTAINABILITY IN SPAIN BY COMPETENCES María LÓPEZ DE ASIAIN1, Pilar PÉREZ DEL REAL1, Jaime LÓPEZ DE ASIAIN1, 1

SAMA, S.C. SEMINARIO DE ARQUITECTURA Y MEDIOAMBIENTE C/ Placentines, 29 - 41004 Sevilla Tel / Fax +34 954 56 00 66 - Email: [email protected]

ABSTRACT: This article presents a reflection regarding the new opportunities that have arisen for the new Spanish architecture curricula adapted to Bologna. Beginning with the study of the new curricula structures and modules in the different schools of architecture and following with the environmental and sustainability related competences[1] and skills an architect should acquire, it presents a proposal of integration of those skills in the curricula in a transversal way. The curricula of two different schools of architecture have been studied in depth, the curriculum of Seville and A Coruña, due to their particular structures based on a workshop module where technical knowledge and design skills are developed in an integrated way. The specific competences that could be integrated in these special workshop modules are developed and the possible methodologies that could be used are proposed. The possible further diffusion and useful integration of these strategies in some other Spanish and European architecture curriculum are studied and proposed as well. These research belongs to the EDUCATE European Project [4] that aims to integrate the environmental sustainability issues and methodologies into the European architecture curriculums. Keywords: education, sustainability, sustainable architecture, competences, learning skills

1. STATE OF THE ART OF ENVIRONMENTAL TEACHING IN SPAIN Spain is currently delved in the process of discussing the powers granted to architects as practitioners. The Ministry of Education, the universities and the National Chamber of Architects of Spain are trying to reach an agreement that does not imply a change of the powers that architects have nowadays in Spain, and also that make sure these functions are not transmitted to other professionals. Within this frame, the Schools of Architecture throughout Spain are working on the adaptation of their syllabuses to the Bologna process. Very few Architecture schools have actually adapted to this protocol and many syllabuses are being developed and therefore are still not accredited nor validated by the Ministry. Due to this situation, in Spain it is difficult to find examples where environmental contents in teaching have been developed and tested, both at undergraduate and graduate level. However, the organizational and methodological structures proposed by some syllabuses show the potential opportunities that they can develop. This is the case of La Coruña and Seville, as we will comment later on. On the other hand, we find some examples – consolidated to certain extent- at the

postgraduate level which specifically work on environmental issues, although only at the theoretical level. As environmental contents are virtually inexistent in the syllabuses at the graduate level, in postgraduate studies it is impossible to introduce practical issues, for the focus is set on the change of mentality and raising of awareness as well as in developing theoretical aspects unknown to the students. These postgraduate studies are the following: Masters in Environmental City and Architecture, University of Seville; Masters in Renewable Energies: Architecture and Urban Planning. The sustainable City 2009, International University of Andalusia (UNIA); Architecture and Environment: Integration of Renewable Energies in Architecture, Polytechnic University of Catalonia (UPC); Urban Environment and Sustainability, Polytechnic University of Catalonia (UPC); Masters in Bioclimatic Architecture, Polytechnic University of Madrid (UPM).In Spain, some environmental contents are found in the graduate syllabuses of the Schools of Architecture of Barcelona and Vallés (Polytechnic University of Catalonia), La Coruña, Granada, Madrid, San Sebastián, Seville and Valencia. The case of the new syllabus of La Coruña –yet to be implemented– is particularly interesting. The degree consists

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of 300 credits and it ends with the presentation and advocacy of a Final Project. The credits of the syllabus are distributed in four-month subjects, each of which corresponds to a module. Teaching is approached through the WORKSHOP as a learning tool. The Workshop is a working space to exchange knowledge and has been conceived to facilitate the confluence of contents of the different subjects around the architectural design project. The aim for this is to ensure optimization of teaching resources and rationalization of student work. This workshop may be the most appropriate space to work on environmental issues to be introduced. The School of Architecture of Seville is introducing a similar workshop in its new syllabus –supported by six teachers who teach simultaneously different architectural disciplines, promoting interchange and an integral approach very suitable to deal with transversal aspects to architectural knowledge such as environmental issues.   2. ENVIRONMENTAL DESIGN IN THE ACADEMIC CURRICULUM OF THE SCHOOL OF ARCHITECTURE OF SEVILLE Since the 1980s, this school has hosted a research group initially called Seminar of Bioclimatic Architecture and later Seminar of Architecture and Environment which has been developing environmental issues and applying them in the teaching methods of the module on Architectural Composition. With the gradual introduction of the 1998 curriculum, the modules "Architecture and Environment" and "Planning and Environment" are created, being elective 1 semester modules of the 4th and 5th year respectively. The theoretical content and methodology of the practical classes of these modules is as follows: Architectural Composition: Knowledge and understanding of the architectural fact in all its complexity from a scientific, environmental, hermeneutic or formal approach. The environment is considered one of the main variables to be taken into account in the architectural and urban project, thereby occupying a prominent place in the program. Conceptual issues are addressed, and examples of environmental architecture and urban design are studied. Students are asked to include these issues in their practical work. Architecture and Environment: Ecological and scientific fundamentals of dwelling. The program proposes a structure and treatment of key issues to be considered when undertaking an architectural project and also

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approaches a design methodology that includes energy-environmental criteria in the development of the architectural project. The student is asked to do an in-depth practical work on a research topic of their choice among the contents of the module. Environmental Planning: Planning and Sustainability. This module considers the relationship between the city and the territory from a sustainability perspective. Urban planning in used and developed as a basic tool for the protection of natural areas and proper management and planning of land in general. It addresses the design of the urban space from a planning methodology that uses sustainability indicators. The students share a common practical work in which, without losing the overall perspective, different groups of students cover a specific topic or a particular field in both the gathering and analysis of information and in the design process. The groups show their work to one another periodically. We should also point out that many modules clearly address environmental issues without actually considering them specifically environmental. Some examples are Physics II, Theory of Architecture, Solar Geometry, Construction III, Construction V, Other Technologies, Organization and Management of Works, Installations, Architectural Design III, IV and V and Solar Energy Installation in Architecture. Moreover, it has to be pointed out that many teachers of this school have shown interest in the gradual introduction of environmental issues, many of whom have been gradually introducing them in different modules of the academic curriculum. Considering that environmental issues are intrinsic to architecture, it is necessary to include, increase and emphasize environmental contents currently present (and those to be included) in core and obligatory modules, so that they are part of the basic training that any architect with a Bachelor degree should acquire. The new syllabus that is now beginning to be developed and taught in it’s first year, is a great opportunity to work on, specially into the new courses developed as workshops supported by six teachers who teach simultaneously different architectural disciplines. 3. ENVIRONMENTAL DESIGN IN THE ACADEMIC CURRICULUM OF THE SCHOOL OF ARCHITECTURE OF A CORUÑA The syllabus the School of Architecture of La Coruña has generated -within its marked structure of annual and semester modules- a

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

workshop space in which students study the relationships between the different disciplines around architectural design. This transversal approach to architectural learning - in which different modules show common aspects- helps students understand architectural design as an exercise of consistency between the different architectural aspects at stake. This facilitates the integration of sustainability issues from every possible angle: technological, social or from a design point of view. During the first year, workshops 1 and 2 will integrate environmental competences regarding the program of needs in architectural design through the architectural design modules. This way, when they establish a program of needs, students will start considering both the needs of the client and the new social environmental requirements. In the second year, architectural design modules deepen into the environmental and sustainability criteria introduced in the previous year. While in the first semester the student begins to develop of urbanization and gardening projects, in the second semester they are provided with the necessary knowledge for the accomplishment of environmental and landscaping studies that can produce measures of protection against environmental impact. In the third year, both workshops of the first and second semester integrate design modules with construction modules, allowing the confluence of contents of both subjects around the architectural project, thus rationalizing the student’s work. The workshop coordinator, before the beginning of the semester, will define the topics and projects that students will do. This way, students will have access to the description of the topics, locations, educational aims and workshop requirements from the beginning, as well as to the plans that will be used in the different modules. In the fourth year the workshop is extended and the module of architectural design -which has always been demanding on environmental adequacy - is interrelated with Urban Planning IV, which incorporates ecology and sustainability criteria, environmental solutions of conditioning, structures, and installations. The last school year students find in both semesters three obligatory modules and some elective ones to choose from. Among the elective modules we find Landscape and Sustainable Habitat, a very important one because of its special relevance in the environmental curriculum of the architect. This module deals with environmental adequacy issues, conditioning projects, ecology and

sustainability. It will introduce the student to environmental land and landscape planning. This way, students will be able to relate the theory behind design issues –oriented towards the scale and rural problematic- with environmental values, concepts, land and urban planning techniques. The module deals with aspects related to habitat and landscape from a sustainability point of view in its three facets: economic, social and environmental. This is carried out through a practical workshop exercise supported on theory lessons, so that the student goes deep into environmental planning. In order to do this, students will have to become familiar with some aspects and documents of their professional competence such as the study of strategic environmental evaluation, environmental impact projects, or intervention projects in areas of great environmental and landscape value with social and economic complexity. Final Degree Project. The fundamental requirement for the presentation and defence of the Final Project is that the student should have already completed the 300 ECT credits. Then, after they have successfully completed the final project workshop and have a favourable report from the Evaluation Committee, they can submit the Final Degree Project to be assessed by an examining board. This analyzed syllabus has been recently approved and this is one of the reasons why one of its main educational aims is developing abilities related to the architect’s responsibility towards society and care of environmental problems. On the other hand Students are not encouraged to study environmental matters in depth as they are always approached in a tangential way in the core modules, and there is little choice of elective subjects to specialize. For the correct teaching of the environmental contents it is necessary to ensure that the teachers have the capacity to integrate the theoretical and technical knowledge in the architectural project proposals, that is, with specific knowledge in fields like scientific, technological, and instrumental development. We find very important in this case to work with teachers in deep about their responsabilities regarding to competences and learning skills to adquire by students in order to be sure that they improve their approach to sustainability by working on their courses programs. In this sense the knowledge base propose by EDUCATE research and the environmental competences to be developed by SAMA in next stages of our investigation would be core opportunities to

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confirm this environmental approach of the syllabus. This proposal can surely take advantage of the different opportunities this syllabuse offer us, such as: • The workshop as the work space for several modules is the perfect environment for students to become aware of the intimate relationships between the factors that affect sustainability in a design project: design, urban planning, materials, constructive typologies, installations, etc. The workshops structure established is perfect to improve relations between departments and to harness the criteria and general aims in an organized way. • The proposed structure allows students to see from the first year how architectural design consists of multiple factors, sustainability being present in almost all of them. • As environmental issues are approached in workshops from the first year, sustainability becomes a regular factor when it comes to designing, and the student assumes it as one of the key points that they should take into account from the very beginning of any design or urbanplanning project. • The insistence upon sustainability issues in architectural design throughout the five teaching years makes the future professional more conscious of their responsibility towards environmental questions, both economic and social. 4. DISCUSSION INSTITUTIONS

WITH

RELEVANT

In order to have a more precise knowledge of major professional initiatives about sustainability in Spain, the CHAMBER OF ARCHITECTS OF SPAIN, CSCAE and SAMA (Seminario de Arquitectura y Medioambiente) openned a nationwide discussion forum. As a result, two meetings were convened attended by representatives of various associations. Some of the final conclusions of these meetings encorage the proposal developed further down. The most important final conclusions in relation to our aproach are: • It seems very important the empowerment of social perception, spreading the need to apply the concept of sustainability in architecture and urbanism and facilitate customer access to these issues not intended as an extra cost to the budget. • The importance and urgent need for the Council and the Architect Institutes to conduct a massive social diffusion of the values of sustainable architecture and urbanism and its tremendous influence and impact on energy

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consumption and climate change is emphasized. • The Green Visa is a service that COAM[2] is developing to offer to society to demonstrate a degree of commitment of certain works with the environment. That means in practice that those projects or buildings with the Green Visa have demonstrated a higher level of sustainable design quality . It is not a compulsory command, but the possibility of having a useful service that will increase the objective value of our productions in the building market. • Furthermore, it is desirable to align the numerous courses and masters programs with a common basic framework, in line with Bologna guidelines for integration into Europe. This is a great opportunity to unify the groups, institutions, people interested in these topics to research and development level and keep them informed and interrelated. • The Continuing Professional Development is particularly urgent when we consider that there are

currently 50,000 practitioners in Spain, plus another 50,000 who will graduate in the next 5 years. These professionals have no specific knowledge to deal with sustainable matters from these parameters. Therefore we need to address a continental system based on University-based training. 5. NEW OPPORTUNITIES IN TERMS OF COMPETENCES AND LEARNING SKILLS The current European regulations support all kinds of educational improvements related to the introduction of energy and environmental issues in architecture, although it is not actually demanded by these regulations. The current Spanish regulations permit the proposed necessary change and even promote it by demanding teaching methods which are more appropriate for the needs of today’s architectural practice, which undoubtedly include environmental and sustainability issues. The interest shown at the Escuela Técnica Superior de Arquitectura of Seville –by students and teachers alike– regarding issues related to the natural environment and architecture allows and fosters de creation of an environmental curriculum that includes this kind of knowledge in the teaching of architecture. The Escuela Técnica Superior de Arquitectura of Seville is currently immersed in the process of creating a new syllabus adapted to Europe, which means this is a great opportunity to introduce environmental contents in the structure of the curriculum.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

In this sense, the headship of the school is working on the introduction of some methodological changes of the curriculum in order to get closer to the proposals developed by the Bologna Process. One of the most important initiatives of the headship is to promote the translation of the syllabus of each module into competences and learning skills that students should acquire, instead of contents to be learned. This way, several projects are being carried out with the purpose of encouraging teachers’ participation in this task in an in-depth and personalized way. The aim of these projects is to involve the biggest number of teachers possible in the development of the competences and learning skills of the modules they teach, which would ensure in the medium and long term a real and clear development of such competences in terms of professional knowledge acquired. We believe that, from the perspective of the EDUCATE project, we can take advantage of these initiatives to work on the introduction of environmental and sustainability issues starting from the development of competences and learning skills. This can be the base for the transversal transference of such competences and learning skills to the complete syllabus of the Architecture School. This way, the process to be followed would be the following: • Development of specifically environmental and sustainability competences that an architect should acquire throughout the different university teaching levels –undergraduate, graduate and postgraduate. For this purpose, a study parallel to the EDUCATE project will be carried out by means of the knowledge base, which provides and ensures all competences and learning skills linked to environmental and sustainability aspects. This project is also supported by the National Chamber of Architects of Spain, which considers possible that such competences can be evaluated in a later stage as a requisite for attaining the necessary qualifications of an architect. • Once the competences are developed, we will work on the syllabus of the Architecture School and the teachers will be encouraged to incorporate in their syllabuses those competences which are specifically environmental. • A group of interested teachers will be selected to work on an in-depth introduction and development of sub-competences for their modules. • Once all competences and sub-competences are developed (sub-competence is understood

as a competence or learning skill which develops in great detail a specific skill linked to a specific module), we will work with the teachers in the shaping of their syllabuses for the following year. We will then test the usefulness of the knowledge base to provide teachers with the relevant tools to carry out this task. • This process of incorporating the environmental and sustainability aspects in the syllabus of the School of Architecture of Seville can be potentially applied to all architecture schools in Spain. Particularly, the schools of A Coruña and Madrid are interested in getting involved in the project. The Seminar of Architecture and Environment (SAMA) intends to work on the proposal for the University of Seville and, depending on the results obtained, to work in a later stage with the other two mentioned universities. 6. REFERENCES [1] Com·pe·tence (k m p -t ns) n. a. The state or quality of being adequately or well qualified; ability. b. A specific range of skill, knowledge, or ability. [2] Colegio Oficial de Arquitectos de Madrid, Chamber of Architects of Madrid, depending on the Chamber of Architects of Spain, CSCAE [3] Lopez de Asiain Alberich, M. La formación medioambiental del arquitecto: hacia un programa de docencia basado en la arquitectura y el medio ambiente. (Environmental Training of Architects: towards a teaching syllabus based on Architecture and the Environment). Doctoral thesis at the Polytechnic University of Catalonia (UPC) within the programme “Energy and Environment Research Fields within Architecture”. 2006. [4] AV. La Enseñanza de la Arquitectura y el Medio Ambiente. Programa Life. Comisión Europea. Dirección General XI. Medio Ambiente. [5] López de Asiain Alberich, María. La energía en la educación medioambiental arquitectónica. Tesis de Maestría del programa: “VI Maestría en Energías Renovables : Aplicaciones en la Edificación” . Universidad Internacional de Andalucía. [6] López de Asiain Alberich, María. Extrapolation of European Experiences in Environmental Architecture Teaching Programmes. International Conference on Engineering Education in Sustainable Development, EESD2004. D. FerrerBalas, K. F. Mulder, J. Bruno and R. Sans (Eds.). Ó CIMNE and UPC Barcelona, 2004 [7] López de Asiain Alberich, María y Cruz López, Yazmin. Curriculum Greenin; For or against the obsolete faculty? 11th Annual International Sustainable Development Research Conference Helsinki, Finland, 6-8, June.

 

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[8] López de Asiain, María, Cuchí Burgos, Albert. ‘Implications of the Term ‘Sustainability’ in Architecture. Teaching Tools for Lecturers.’ A: Environmental sustainability. The Challenge of Awareness in Developing Societies. Notre Dame University Press, 2005, p. 821-824. [9] López de Asiain, María; Echave, Cynthia; Fentanes, Karla. ‘A Methodological Approach to the Transference of Knowledge.’ A: Environmental sustainability. The Challenge of

   

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Awareness in Developing Societies. Notre Dame University Press, 2005, p. 979-983. [10] López de Asiain Alberich, María. ‘Reflections on the Meaning of Environmental Architecture in Teaching’. A: Plea proceedings: Built environtments and environmental buildings. M de Witt / Technische Universiteit Eindhoven, 2004, p. 163-168. [11] EDUCATE Project financed by the European Project INTELLIGENT ENERGY EUROPE (IEE) - CALL CIP- IEE – 2008. http://www.educatesustainability.eu

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

A Prototype from the Solar Decathlon Competition becomes an Educational Building in Sustainable Architecture M. Carolina HERNÁNDEZ-MARTÍNEZ1, César BEDOYA2, Alfonso GARCÍA-SANTOS1, Javier NEILA1, Estefanía CAAMAÑO2 1

Department of Construction and Technology in Architecture, School of Architecture, Universidad Politécnica de Madrid, Madrid, Spain 2 Instituto de Energía Solar, Universidad Politécnica de Madrid, Madrid, Spain

ABSTRACT: In 2008, the City Council of Rivas-Vaciamadrid (Spain) decided to promote the construction of “Rivasecopolis”, a complex of sustainable buildings in which a new prototype of a zero-energy house would become the office of the Energy Agency. According to the initiative of the City Council, it was decided to recreate the dwelling prototype “Magic-box” which entered the 2005 Solar Decathlon Competition. The original project has been adapted to a new necessities programme, by adding the necessary spaces that allows it to work as an office. A team from university has designed and carried out the direction of the construction site. The new Solar House is conceived as a “testing building”. It is going to become the space for attending citizens in all questions about saving energy, energy efficiency and sustainable construction, having a permanent small exhibition space additional to the working places for the information purpose. At the same time, the building includes the use of experimental passive architecture systems and a monitoring and control system. Collected data will be sent to University to allow developing research work about the experimental strategies included in the building. This paper will describe and analyze the experience of transforming a prototype into a real durable building and the benefits for both university and citizens in learning about sustainability with the building. Keywords: sustainable architecture, solar energy, education, professional training

1. INTRODUCTION The Solar House-Energy Office building is based and inspired in the Project “Magic –Box”, developed by the Universidad Politécnica de Madrid (UPM) to enter the international competition Solar Decathlon 2005 in Washington, D.C. [1] This competition was promoted by the Department of Energy of the United States of America, with the main aim of promoting possibilities of combining good practice with a reasonable use of energy by means of passive and active use of solar energy and efficient technologies. The proposal of the UPM team consisted of the design, construction and operation of a single house of around 70m2. The participation of the UPM was an extraordinary multidisciplinarian experience on research and education. Teachers and students from different disciplines collaborated together in order to achieve sustainability by means of combining bioclimatic architecture, use of solar technologies and domotics. The principal objective of the proposal was developing a small electrical self-sufficient dwelling. It was immediately evident that it represented a very broad and ambitious goal; even so the UPM Solar Decathlon team understood the proposal as a global challenge in terms of habitability, pollution, energy, natural resources, materials and sustainability. The project, called Magic-Box, desired not only being electrically self-sufficient but also bioclimatic, and full of European, Mediterranean and pure Spanish spirit. The team understood the local regionalism as a different way of aesthetically experiencing the

architectural space, physical construction and life inside the house. The dwelling was open to surprise, movement, continuous exploration and enjoyment. A great many layouts were possible, since a number of movable walls allowed the occupants to unify or compartmentalize its interior space. Façades followed a modular scheme yet each was designed according to direction and time of solar radiation. The roof was independent of the livable volume yet preserved a compositional role, extending its appealing wavy shape to the remainder of the lot and the external pieces of furniture.

Figure 1: Original Magic-box prototype

The main features of the MAGIC BOX were: passive design; the application of traditional strategies for winter and summertime, day and night, commonly used in Spanish vernacular architecture, although they were implemented by means of new

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technologies, materials and systems; and the rational use of architectonical elements, such as porches, greenhouses, green roofs, vegetation, eaves, louvers, sliding panels, and even a “folding” patio. All of these were employed to manage comfort conditions, light and air quality, to control solar penetration, ventilation and thermal storage, as well as to define formal composition and to treat light and color. Electricity came from photovoltaics and heat storage was made possible through passive or active solar heating from evacuated tube solar collectors and free cooling at night in the summer. All indoor devices were operated through an integrated domotic system. The building was set out to be bioclimatic to the highest degree. In this instance, the term “bioclimatic” refers to the relation of climate and life, both in the natural and man-made environment. Consequently, great importance was given to air quality and ventilation, to necessary levels of thermal comfort and humidity and to an adequate distribution of temperature in the rooms. The house was characterized by simplicity, versatility, layout consistency, easy use in both the inside and the outside. Such relation with the environment not only highlights its visual and spatial aspects, but also fosters efficient consumption of materials, resources and energy, together with the minimizing of the production of waste. One of the aims of the Solar Decathlon competition is to raise societies´ awareness of the need to use energy responsibly which is coincident with the City Council of Rivas-Vaciamadrid general aim in sustainability. The idea of reproducing the Magic-Box house as a new building is an initiative of the City Council of Rivas-Vaciamadrid, adapting to a new necessities program to house the Energy Agency office. It is intended to be a space for attending citizens for everything related to saving energy, energy efficiency and sustainable construction. The house will be visited by people, fully accessible to fulfill a didactic objective, holding also a permanent exhibition space and workstations for the information office. The Solar House-Energy Agency building is integrated in the Plaza Ecópolis project. It is a new space for the city which houses a park and playground surrounded by a kindergarten, an exhibition hall focused on energy and the Solar House-Energy Agency office.

 

2. DEVELOPMENT OF THE PROJECT 2.1. The educational and training experience In 2005, the Solar Decathlon UPM Team was a real example of multidisciplinary content, with institutions having proven experience in Education, R&D within the fields of Photovoltaics, Architecture and Domotics. A total of 40 students and 8 faculty members was coordinated by the Institute of Solar Energy of the UPM.[2] The common aim was to involve the university community as much as possible. Three different

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groups were created specializing in the main areas: architecture, energy systems and domotics. Besides these, other small sub-groups were created for specific purposes such as communications, logistics and sponsor funding. Project planning was structured according to five subsequent phases running for 25 months: 1) Conceptual design, market & regulations analysis and, web-site setup. 2) Architectural design & schematic energy analysis. 3) House construction & equipment. 4) Final house preparation & tests. 5) Solar Decathlon event & evaluation. After the competition, the “Magic Box” was shipped back to Spain, where it was rebuilt and fully equipped in its final site at the UPM premises. The 2005 prototype was installed in the University Campus and became a laboratory for the University. For information, there is a further copy of the house reproduced in Beijing, representing Spain in the Future House exhibition. The UPM team maintained R&D activities on the concepts addressed by “Magic Box” until 2007, within a project co-financed by the Spanish National R&D Plan. The aim of this project was to analyze, in detail, the house energy behaviour, as well as to propose modifications to adapt its design and systems to different Spanish climate conditions, house typologies and environments (grid-connection with backup). Since then, the house has been periodically shown to students, scientists and the general public with great success: overall, more than500 people see the house every year. The authors can also say with pride that this experience inspired later participations of UPM in the Solar Decathlon competition in 2007 and 2009 [3], as well as profiting from the previous practice and achieving a deep experience that allowed the University to be part of the organization of the first edition of the Solar Decathlon Europe, held in Madrid in June 2010. In 2009 a new team was created to face the new challenge of rebuilding the Magic Box. It was formed by people from ABIO Research Group (Bioclimatic Architecture in a Sustainable Environment), researchers from the IES (Institute of Solar Energy) and members of the TISE Research Group (Innovative and Sustainable Technologies in Building), and all three of them from the UPM. The group was made up of architects, urban planners, engineers and industrial designers – a very broad range of practitioners.[4] In essence people from different backgrounds were obliged to work together cooperatively, and in this respect the project mirrors real life. The ABIO office became a professional architecture office without disrupting the normal research and teaching activities. The Project Planning had at this time a single phase: to start and to finish in only two intensive months. There has been again a multidisciplinary group of architects and engineers collaborating in a small but very special project. The team integrated undergraduate, master and PhD students as well as

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

faculty members. Only approximately 10% of the team was part of the 2005 original team. Difficulties presented when adapting the prototype to comply with building regulations without compromising the original style and appearance. Hence, some of the materials used in 2005 were not manufactured or sold any more. The biggest difficulty was that the budget available was insufficient for affording some parts of the original design as expensive pieces of furniture had been funded or donated for the original Solar Decathlon competition. At this point, workers from the Energy Agency and Technology Department of the City Council of RivasVaciamadrid were involved as part of the design team, working together to convince companies to donate material and appliances to the project. The Telecommunications Department of the City Council was also involved in decision making and design for the way citizens were going to be informed about the building performance when it would be finished.

Figure 2: Floor plan of the Magic-Box original prototype

2.2. Taking up again the original prototype When the opportunity to rebuild the house occurred, it was necessary for a full revision of the 2005 project, mainly designed and built according to the American Building Code. It was also necessary to adapt it to the Spanish Building Technical Code, published in 2007, after the initial design. First decisions taken that essentially changed the original project: In terms of construction: ƒ Deep foundation by pilots according to new characteristic of the ground that do not allow supporting big loads. ƒ Steel structure instead of light-weight steel and timber structure. ƒ Concrete cellular insulating blocks instead of steel and timber enclosures. Building services: ƒ Ground source heat pump and fan coil system. The house must be fully efficient all the year round and in extreme winter and summer conditions of continental climate passive strategies may not cover all necessities. ƒ To improve the design and performance of the passive energy storage system PCM based. Solar energy: ƒ The new building is not a stand-alone PC system but a grid connected system. Architectural design: ƒ The new office spaces would be connected to the house on the north side, with 3 work stations. ƒ The “hinge” piece would be a wide corridor holding a building services room for solar inverters and office storage use, and a handicapped accessible bathroom. The new façade rain screen of this module would be a green wall. ƒ The disappearance of the living-movable room to avoid safety problems in a public building

Figure 3: Floor plan of the Solar House-Energy Agency office building in Rivas-Vaciamadrid

Since agreement was established, the architecture office tasks have been completed in record time to allow the City Council to arrive, before the deadline, to participate in the benefits granted in the Plan E for the Incentive of Economy and Employment. This Spanish Government plan established the possibility of funding a large quantity of local projects in order to promote employment in the construction sector hardly damaged during the present day’s global economical crisis. The construction site has been developed during 2009 and 2010. The Solar House-Energy Office building, together with the other two buildings of the th Plaza Ecopolis was inaugurated in September 24 .

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

3. THE BUILDING AND ITS BIOCLIMATIC DESIGN The building seeks to illustrate an example of sustainable construction according to the objectives promoted by the City Council and the Energy Office. It is a building that demonstrates that sustainability and self-sufficiency are possible, showing with clarity and simplicity how to achieve it. The renewable energy produced by the building is more than its energy consumption. It is not only a zero energy building but a building that introduces renewable energy to the electrical grid. In the same way, it can be considered a non carbon emission building because the surplus of produced energy allows compensating the emissions produced during the manufacturing process of materials used in the building construction. Besides, most of those materials have been selected according to the Life Cycle Assessment methodology, choosing materials with a low electrical energy consumption during manufacturing process or recycled materials, as the outside external spaces and windows framing. Renewable materials have been also considered as wood fiber insulation. In addition, the use of green roof as a drain of CO2 and two green walls panes allows us to reduce the global balance of the building, already converted in a zero emissions building. The building produces electrical energy by means of photovoltaic generators, hot water by evacuated tube solar collectors and energy for conditioning mainly by means of a passive system. The passive system incorporated in the building should cover most of comfort necessities during summer, and a major percentage during many hours in winter time. When it is not covered by the passive system, the thermal source pump with high energy efficiency will contribute to supplement the shortfall in energy. The passive system is mainly a collecting and storing energy system to allow using it for 24 hours a day and to be a mechanism of distribution to the different parts of the building. A storage system is essential in any building that collects energy during very short hours during the day time and that should distribute it during the remaining parts of the day. The system installed is a collection of devices that contain phase changing material (PCM) settled at 23ºC. The PCMs store or release energy during the phase changing, when solidify by storing cold, and storage heat while becomes liquid. The PCM used is paraffin based [5]. These substances are located in the raised technical floor and this is the place where energy is going to be stored. A part of the PCMs are inside cylindrical recipients settled in EPS moulds located under every piece of the raised floor. Every metallic cylinder facilitates the exchange of energy with the air forced to circulate between them. The flooring tile is on a metallic mould also filled with PCM. [6] Winter conditioning system is based on solar radiation and internal loads (the heat generated by occupants, lighting and any electric equipment working inside the house.) In order to collect solar radiation two big window panes forming small

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greenhouses occupy 2/3 of the south façade. Every single green house has a double skin: the first single glass pane to facilitate solar radiation collection and the second one to isolate and avoid heat loss. A great quantity of radiation passes through the greenhouses and directly heats the floor. A part of this heat is retained in the green house that, in case of necessity, may pass into the house by the tilt bottom hung motorized opening of a single window pane.

Figure 4: Winter time: bioclimatic performance.

Summer time conditioning system is based on taking advantage of the night cool that in Madrid’s climate is under the comfort temperature established as 25ºC in this period of the year. Cool air is collected in the north façade passing through a garden zone to allow an evaporative cooling and conducted under the external flooring. It is forced to circulate through the raised technical floor as far as the south façade. Once it has given its energy to the PCMs located there, goes out through the grates located in the greenhouse floor whose external glass skin should be folded and acting only as vertical shading. There is a conventional supporting system that allows re-circulating air inside the building. It is made up of the ground source heat pump mentioned before, that works when the passive system does not cover all conditioning necessities and a fan coil that transfers the energy produced by the pump to the rest of the building. Once the air is pumped to the office area, it goes through the grates located on the floor and some fans facilitate it to circulate through the technical floor passing between the recipients with the PCM. During this journey, the air is charged with the energy accumulated in the paraffins, i.e. heat in winter and cool in summer. This air goes out through the south facade grates, on the internal side of the glass enclosure in winter and on its external side in summer.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The Energy Agency will also manage the project Rivas Solar that works to extend the generation of thermal and photovoltaic solar energy throughout the city. The Energy Agency coordinates and promotes the project RIVAS ECÓPOLIS [7] whose target is to transform all the city of Rivas Vaciamadrid to become more sustainable. Rivasecopolis has been conceived as a “city project”, absolutely integrated in the City Council structure All citizens who go to the Energy Office will be able to visit the house according to an educational and didactic aim. Posters and explicative panels will allow then to obtain detailed information about every single system working in the building as well as explanations from the people working in the Agency.

Fi

Figure 6: The Energy Agency office building. External and internal views

Not any single one of these conditioning systems would be efficient enough if the building would not perfectly conserve its energy by means of reducing its necessities. Insulation levels of façades, floor and roof have been raised beyond those minimums established in building regulations. All possible thermal bridging has been carefully studied and solved. All the design has been refined to create a quasi adiabatic envelope, reducing to the minimum the exchange of energy between the building and the environment. The air recirculating in the house has been taken from the outside in the south green houses in winter and at night directly to the raised floor plenum in summer. Thus, before entering the house, the air has been favorably modified between 5 and 10ºC. The expenses on ventilation have been also minimized.

The house is completely furnished and working (fully equipped kitchen, appliances, bathroom, etc) as an ordinary house. Two screen displays located in the living room will illustrate and explain the performance of the building. Simultaneously, there is the possibility of observing the energy produced by other public buildings also controlled by the City Council. In the same way, the values from the Solar House-Energy office can be remotely checked by visitors to those other public city buildings.

gure 5: Summer time: bioclimatic performance.

4. SOLAR HOUSE + ENERGY AGENCY OFFICE BUILDING 4.1. Visiting the Energy Agency office The Energy Agency is a city public service depending on the Urban Planning, Sustainable Development and Maintenance Department of the City Council. It was created in July 2008 with the aim of converting the city to an example of efficiency, saving energy and citizens’ commitment to the present crisis of the energy model. The Energy Agency promotes a new way of looking at energy, of using natural resources and responsible consumption. The main objective is assessing citizens and companies based on Rivas-Vaciamadrid in all issues related to saving energy and energy efficiency, clean and renewable energies, sustainable transport, ecological footprint, etc.

4.2. Collected data for research In order to obtain data to develop research, all the Energy Office building is being monitored. The control system is registering data available for 3 different targets: 1. The property (the City Council) is obtaining data on consumption and energy saving, 2. The citizens can observe and learn about the building performance. There is a net established between some public buildings in the city and it is possible to check the energy production of all them from every single building. 3. The University is receiving the data lists to compare with the results considered in hypothesis and with the data obtained in the laboratory tests with the results while the real system is working. A weather station and a PV calibrated cell have been installed in the roof. Thermostat and different temperature and humidity sensors and located in every single space of the building as well as under the raised technical floor. All the instant values obtained are shown in the displays located in the living room area of the house.

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Table 1: Parameters being controlled and monitored in the building

BUILDING SYSTEM PV System

PARAMETER Instantaneous production Cumulated production per day Cumulated production per month Cumulated production per year Electrical consumption per day Electrical consumption per month Electrical consumption per year

Conditioning

Outside temperature Inside temperature in every space of the building Fan-coil. In-take air temperature Fan-coil. Egress air temperature

Ground source heat pump

Instant energy production

6. ACKNOWLEDGEMENTS

Energy production per year

We are grateful to the “Solar Decathlon UPM 2005 Team” for their generous effort and dedication. The first prototype would never have seen the light of day without their support. The Energy Agency building has been constructed with the financial support of the city council of Rivas-Vaciamadrid and the Government of Spain, in the framework of the Plan E for the Incentive of Economy and Employment. Many thanks are given to the City Council of Rivas-Vaciamadrid for being interested in our prototype and for the aim to promote sustainable architecture and encourage their citizens to live in a sustainable attitude.

Instant energy consumption Energy consumption per year Energy storing raised floor

Temperature of entering air Air temperature inside the technical floor Temperature of egress air PCM material temperature Hatch´s position open / close Air fans on / off

Green walls

Water consumption

Green roof

Water consumption

Data will be regularly sent to University to allow to quantify and to characterize the results. For instance, simultaneously a sample of the prototype of the passive energy storing system integrated in the technical floor is already being monitored in University laboratories.

5. CONCLUSION The Solar House- Energy Agency building is an example of sustainable construction because in global quantification it does not consume energy, neither the building itself nor taken from the electrical net. Renewable energy generated by the building itself is greater than the energy consumed. Hence, it is not only a zero-energy building but a building that incorporates energy into the electrical grid. As a shared objective with the Solar Decathlon Competition, the building intends clearly showing that solar houses can be built without sacrificing energy efficiency or comfort, and that they can be both attractive and affordable. The benefits of the experience of entering the Solar Decathlon Competition are unquestionable for a University. From an educational perspective, the experience initiated with "Magic-Box" has been

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unique. Students could learn what a real project is and the need to integrate several disciplines in building-related projects. Professors also found the project very stimulating and rewarding The experience has been reinforced when having the opportunity of reconsider about the proposal, redesign and convert the prototype into an absolute real building. For some of the students involved in the experience, it has been the first approach to professional practice while being undergraduate students. They have had the opportunity of working on design, budget planning, specifications as well as construction management. The holistic view of the experience reveals a double immediate benefit in education in sustainability: the building itself is a real clear and tangible demonstrator for citizens visiting the office and house and at the same time it allows access to a real scale testing sample for university students.

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7. REFERENCES [1] Caamaño, E. et al. Viviendas solares autosuficientes: participación de la Universidad Politécnica de Madrid en el concurso “Solar Decathlon”. Informes de la Construcción, 2004, Vol. 56, p. 35-46. [2] Caamaño, E. et al. Spanish participation in the “Solar Decathlon 2005” competition: new th proposals for zero-energy houses. Proc. 20 European Photovoltaic Solar Energy Conference, Barcelona – Spain (2005), 2587 [3] www.solardecathlon.upm.es [4] Derome, D. Pearl, D. and Athienitis, A. Engaging Engineering and Architectural Students in the Integrated Design Process (IDP) for a competition Entry Demonstration House – the st Solar Decathlon. Proc. 21 PLEA conference, Eindhoven - The Netherlands (2004) [5] Hernández-Martínez, M.C. et al. Phase change material capsules for thermal storage purposes in housing. Proc. SEEP 2009, 3rd International conference in Sustainable Energy and Environmental Protection, Dublin – Ireland (2009), 350. [6] Cerón, I. et al., this conference. [7] http://www.rivasecopolis.org

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Passive and Low Energy Architecture in Education of Contemporary Architecture Barbara W IDERA Faculty of Architecture, Wroclaw University of Technology, Wroclaw, Poland ABSTRACT: At the beginning of XXI century climatic and sustainable design has been the most actual topic of contemporary architecture. Education of young architects in this area of knowledge should become as advanced as possible. Showing clearly that passive and low energy architecture is not a temporary fashion but the new way of thinking and does not have to be connected with any particular current should become one of the most important goals for the educators. The rich and original exemplification is very important in the teaching process. It helps student understand how sustainable design works in practice. In consequence they are more open for new challenges and creative solutions. Theory and practical experience should be connected in the whole education process. International cooperation, conferences, workshops and practices as well as students contests are highly recommended so that the good examples can be followed and the young generation of architects will promote the worldwide campaign for passive and low energy architecture of the future. Keywords: education, architecture, energy, bioclimatic, sustainable 1.

INTRODUCTION

At the beginning of XXI century climatic and sustainable design has been the most actual topic of contemporary architecture. Education of young architects in this area of knowledge should become as advanced as possible. Nevertheless teaching practice seems to stay behind the science and technology. Certain efforts to change this fact have been undertaken. It is vital to diversify the educational process and to follow the theoretical knowledge with practical works. It is also essential to raise students’ consciousness that the architecture safe for the environment has been an unavoidable need of our times on one hand, but on the other hand does not result with any limitation of individual style nor creativeness of the author. 2.

THE NEW APPROACH TO ARCHITECTURAL DESIGN

2.1. Common Welcome

Philosophy,

Any

Style

designed by Najjar & Najjar Architects (2010), represents the example of low energy building. On the southern and western side of the house the roof cantilevers beyond the terraces to provide en efficient sun protection in the summer while in the winter the low sun angle allows controlled entry of the natural light into the interior space.

Fig. 1: Villa A, Linz, Austria, designed by Najjar & Najjar Architects (2010) represents an example of low energy building. © Manfred Seidl.

is

XXI century should start with the radical change of typical but old fashioned approach presented in the polemic between Peter Eisenman and Leon Krier “My ideology is better than yours” (Eisenman, Krier 1989) [1]. Many designers believe that climatic architecture has been a part of Eco-Tech movement which they regard to be nothing but the evolution of High-Tech logic. For the opponents that kind of design does not leave enough space for the creativeness, imagination and personal style of the designer. Showing clearly that passive and low energy architecture does not have to be connected with any particular current should become one of the most important goals for the educators. Villa A (Fig. 1), located on the slope of the Poestling Berg, a mountain in Linz, Austria,

Fig. 2: Villa A, Linz, Austria, Najjar & Najjar Architects (2010). Daylight can enter through the openwork roof and terrace glazing. © Manfred Seidl.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. The large scale glazing have been supported with reflections from the pool near the house as well as from white walls, pavements and other interior surfaces, in purpose to reduce using the electric light during the whole year (Fig. 2). Daylight can also enter through the roof glazing between the lower floor and the upper terrace (Fig. 3). It has been combined with the shape of the openwork roof. This implementation of passive energy concept has been followed by the recuperator in the ground and photovoltaic panels on the roof (Najjar, Najjar 2010) [2]. Natural ventilation has been also provided. Indoors and outdoors space blurs smoothly and the idea of green architecture has been connected with individual style which resulted with contemporary, elegant forms. This is very important to take care about esthetic and cultural side of the sustainable projects because, as it has been pointed out by James Wines, sometimes the enthusiasts of advanced technology try to present it as a very complicated challenge and the reproachable character of their comments may discourage persons who do not accept the technological forms. As Wines notes people are often attracted by apocalyptical visions and fantastic project of salvation but they do not really see anything particularly interesting in photovoltaic panels or low-emissivity coatings (Wines 2000) [3].

understand ecological tasks and to meet them in the most positive way is an important goal, emphasized by the architect (Despang 2007) [6].

2.2. Not another fashion

Fig. 3: Villa A, Linz, Austria Najjar & Najjar Architects (2010). Daylight enters through the roof glazing between the lower floor and the upper terrace. © Manfred Seidl.

Though environment protection must be understood by this generation as the crucial condition of surviving for our planet and the whole humankind, still many people think that sustainable design is just a new fashion. They emphasize high costs of climatic buildings, believing that with the time architects will simply change they mind and step into another style, leaving the investors with expensive edifices. It is vital to convince students during the education process, that the low energy architecture is based on logical solutions, does not always have to be so expensive and the idea will not change next season. The good example of passive energy but also low cost building can be observed in Hanover, Germany. Postfossil Ecowoodbox Kindergarten, designed by Despang Architekten (2007), replaced an old, prefabricated structure and, as Van Uffelen points out, covered almost the same area so that the existing soil sealing and elements of the building could be reused (Van Uffelen 2010) [4]. As shown in Phaidon Atlas of 21.st Century World Architecture (2008) [5] light wooden structure and highly insulated timber cladding create natural look of the building, making it a promising exception from a nearby architecture of a 1950s suburban area of the city. Solar energy gained through the curved triple-glazed south facade has been used to heat the rooms (Fig. 4). Providing natural light and contact with the nature is a necessity in this kind of facility (Fig. 5). Nevertheless in this particular case Despang Architekten paid special attention to educational aspect of the project. The young generation not only should enjoy the building to grow happily and have fun, but also should learn here. Helping children to

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Fig. 4: Postfossil Ecowoodbox Kindergarten in Hanover, Germany, designed by Despang Architekten (2007). South facade. Photography courtesy of Martin Despang.

Fig. 5: Postfossil Ecowoodbox Kindergarten, Hanover, Germany, Despang Architekten (2007).Curvilinear facade maximizes solar exposure. Photography courtesy of Martin Despang.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 2.3. Underwater Architecture When we think about sustainable design we often stress its self-sufficiency. Some attempts to create underwater habitual space for human had been undertaken both in 20-th and 21-st century. In this case the aspect of self-sufficiency became natural. On the other hand when people try to inhabit the new, underwater environment, they seem to have a little bit more respect for the nature. Presentation of these ideas could be an interesting diversification in educational process, especially because it has not been connected with particular architectural style or current. In many cases it helps students to open for new challenges and in consequence to look for completely new, creative solutions in the field of architectural design. From many projects and research undertaken in 20-th century the most famous ones were those carried out by Jacques Cousteau. The series of experiments known as “Conshelf” (Continental Shelf Station) proved that it is possible for the man to live and work in specially designed underwater houses without coming out to the surface. Today some visions for aquatic cities have been proposed by architects like Jacques Rougerie or Vincent Callebaut. In most of cases contemporary ideas concern rather floating than underwater objects. In Lilypad project (2008) Callebaut emphasizes the fact that this amphibian city could grant the housing for future climatic refugees from places like Polynesian atolls. The sustainability and self-sufficiency became one of the main objective of the author (Callabaut 2008) [7]. The multifunctional program of Lilypad has been organized around the artificial fresh water lagoon, collecting and purifying rain water but also ballasting the whole city. Creating the harmonious coexistence between man and nature has been the main goal in this territory, dedicated to nomadism and urban ecology in the sea. The idea of the floating city has been inspired by the aquatic plant, the great Amazonian lilypad. The double skin is made of polyester fibers and covered with titanium dioxide which by the photocatalytic effect helps absorbing the atmospheric pollution. The structure is entirely self-sufficient and recyclable, with zero CO2 emission. Usage of all renewable energies (solar, thermal and photovoltaic, wind, hydraulic and osmotic energy) has been proposed in the project. The whole system is supported by tidal power station as well as phytopurification and biomass, so that the city can effectively produce oxygen and electricity without causing any pollution or other harm to the ocean or its inhabitants. Although this kind of project may be perceived as an utopian vision, still it opens new way of thinking and stimulates students imagination. 3.

constantly. Nowadays ability to create passive and low energy should commence to be an absolute standard for the young architects. It is necessary to start their professional education with simple projects where students use basic knowledge about sustainable technology. After having faced these problems for the first time, students should continue with the seminary to have an opportunity to discuss, together with the moderator, some interesting contemporary solutions, developed for the climatic architecture. Parallelly they should join the group, working on another project, in purpose to meet more advanced requirements of sustainable design and to deal with some real, not only theoretical questions. This way theory and practical experience should be connected in the whole education process, so the students really understand the environmental issue and start to believe enough in themselves. In consequence they will not try to escape from these problems in their future architectural practice.

Fig.6: Lilypad project of sustainable self-sufficient floating city, Vincent Callebaut (2008). Drawing, based on Callabaut’s model, by Barbara Widera.

EDUCATION BASED ON SHOW-EXPLAINENCOURAGE SCHEDULE

3.1. Teaching process It has been repeated for ages that the teaching process should start with the basics. Nevertheless the understanding of “basics” tends to change

Fig. 7: Ecohouse, Hill End, Australia, Riddel Architecture (2010) is located on the narrow riverfront side and has been opened to the landscape wherever it was possible. Photography by Christopher Frederick Jones.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 3.2. Exemplification Teaching how to create sustainable and climatic architecture becomes more and more common in designing practice. At the same time very little effort to implement the idea into history and theory of contemporary architecture education has been undertaken. For many students sustainable design looks attractive but too complicated. To deal with this point of view academic teachers should spend some time showing examples of well designed buildings and whole complexes, explaining how they work and encouraging students to develop their own ideas based upon presented objects. It is also very important to make clear the fact that some of the solutions may be used and pay off not only in huge, governmental or corporate buildings, but also in really small and totally various projects, like village shops, nursery schools, dance studios or private houses. Examples from different regions should be chosen to illustrate how ecological architecture may work and deal with various climatic, social and cultural conditions. Riddel Architecture, the authors of Hill End Ecohouse in Hill End, inner Brisbane, Australia (2010) demonstrate how the private residence could replace an old house, be constructed in 80% from materials recycled from the previous building and occupy the same footprint. To the top of that all additional materials were locally sourced and have undergone rigorous assessment of their environmental, social and economic sustainability credentials. Ecohouse is located on the narrow riverfront side and has been opened to the landscape wherever it was possible (Fig. 7). Robert Riddel and his team: David Gole, Emma Scragg and Simon Boundy explaine that large openings help to capture cool breezes and daylight to reduce need for artificial lighting and to provide natural ventilation (Riddel 2010) [8]. Open plan allows an easy access of fresh air and natural light into the rooms and simultaneously creates informal, relaxed atmosphere (Fig. 8). Light-colored finishes maximize reflection of daylight. For optimum efficiency LED and compact fluorescent lamps have been used. The house is fully self sufficient in both water and power and has a monitoring system to measure the use of energy, gas and water as well as temperature and humidity. The north-facing roof has 3kW photovoltaic panels. The sun’s energy is captured to provide hot water and grid-connected electricity to supply the whole house's needs. An efficient gas fire provides winter heating to the southern living space, where, in Australian conditions, solar heating is not possible. The house has recycled polyester bulk insulation and timber frames to reduce heat transfer. Eaves and awnings give sun and rain protection. A drop down louver to the River Terrace provides shading from the morning sun while the north balcony has been sheltered by a trellis with deciduous vines. 60,000L of rainwater storage supplies the whole house and garden. House rainwater is pre-filtered, heated by solar panels and stored in a wellinsulated tank. To reduce water waste, a hot water

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recirculation unit reheats cold water and greywater is treated and recycled on site.

Fig. 8: Ecohouse, Hill End, Australia, Riddel Architecture (2010). Open plan allows an easy access of fresh air and natural light into the rooms and creates informal atmosphere. Photography by Christopher Frederick Jones

Fig. 9: Ecohouse, Hill End, Australia, Riddel Architecture (2010). Terrace has been open both to south and east. Photography by Christopher Frederick Jones

The swimming pool is minimal in size and uses an efficient pump/filter system. It is filled and topped up with rainwater and lit with locally-made LED lights. The house has been a good example of an interesting and original architecture where the authors take maximum advantage of specific location with the benefit both for the residence owners and the environment. 3.3. How to use the examples The teaching experience has proved that well chosen examples can be remembered for a long time with very positive effects. In the preceding

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. paragraph the specific example had been used to put attention on the building’s orientation. In Europe, that is in the northern hemisphere, south-facing windows require some external protection to prevent overheating during the summer and to control glare. North-facing windows do not require shading, but they are not suitable for solar heating. Naturally in the southern hemisphere it has been opposite. European students of architecture, accustomed to northern conditions, were for the first moment surprised with the fact that in Ecohouse southern part of the building needed supporting heating system, while the trellis had been located from the north. Very soon they realized that we were talking about the southern hemisphere, which they missed for the first moment. Once having focused on the orientation topic they have also discussed the article in which the experts from Labs for the 21st Century (2003) claim that “East- and west-facing windows are not recommended for daylighting because it is difficult to control glare and heat gain, especially on the west side (Laboratories for the 21st Century: Best Practices 2003) [9].”

They used a CorTen corrugated steel cladding and exposed steel beams on the interior (Fig. 12).

Fig. 10: Silo House by Cornell University Team (2009). Three “living” cylinders are organized around central courtyard. The photovoltaic panels are floating above the structure. Photography by Chris Goodney

3.4. Helpful Inferences Exemplification is an important part of teaching process since it helps to remember how sustainable ideas work in practice. Nevertheless it is very profitable to spend a little bit more time and ask students to form inferences and to sum up some best features of the buildings they have been shown during the classes. In consequence they will understand given examples and remember their own conclusions much better. 4.

INTERNATIONAL COOPERATION

It has been a common truth that what people really do speaks much louder than what they say. Though it is very important that students and young architects can meet they older colleagues from other countries and find out that the sustainable and climatic design became a regular practice in architectural offices. Competitive approach also has been a good idea. During contests students motivate each other and the result is usually much better. The Solar Decathlon Competition is one of such contests. In this international competition various college and university teams compete to design, build and operate the most attractive, effective and energyefficient solar-powered house (U.S. Department of Energy Solar Decathlon 2010) [10]. Silo House, designed by students from Cornell University, New York, has been one of the most interesting project presented during the competition in 2009. The original idea is based upon the three “living” cylinders, organized around central courtyard with the rectilinear array of photovoltaics, floating above the entire structure (Fig. 10). Bedroom, kitchen and the living room, situated in separate cylinders, can be totally opened to the central part with the usage of operable glass wall system (Fig. 11). The authors’ inspiration for the cylinders came from industrial agricultural materials (Cornell University Solar Decathlon, Silo House 2009) [11].

Fig. 11: Silo House by Cornell University Team (2009). Living spaces can be totally opened to the central part with the usage of operable glass wall system. Photography by Chris Goodney.

Fig. 12: Silo House by Cornell University Team (2009). Steel construction has been exposed but sustainably forested hardwood provide light and natural look. Photography by Chris Goodney.

The electric system of the house is composed of photovoltaic panels, grid-tied inverters and a smart load panel. Silo House has fully-functioning kitchen, home theater PC with eco-friendly LCD, 1 GB network and even electric toilets. Excess power generated in the house is sold back to the grid. Solar gain from the steel envelope through an innovative skin-integrated solar thermal system has been used to pre-heat hot water. Additional light diffusion and stack ventilation have been allowed

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. through the operable Velux® skylights, two in each cylinder. Materials were chosen locally with strong environmental conscience and much care to utilize sustainable, regenerative and environmentally benign materials. Black locust, ash and beech hardwoods, also locally sourced and sustainably forested provide natural and light look inside the house. Only zero off-gassing finishes have been used. It is worth noting that the team did not just finished the house and forget the project but the organization has been constantly active. Team members run the website, update the information and even arrange trips, so that the other people may see their works and understand how the sustainable buildings can operate in practice (Cornell University Sustainable Design 2010) [12]. 5.

CONCLUSION

Even after a perfect presentation and the most logical argumentation some students tend to ask who cares. It is finally time to say “We care” in as many languages as possible. That is why constant education, international conferences, workshops and practices are so important. Hopefully the good examples will be followed and the young generation of architects will promote the worldwide campaign for passive and low energy architecture of the future. 6.

ACKNOWLEDGEMENTS

The author wishes to thank the architects and photographers of presented buildings who not only allowed their permission to publish but also offered amazing support and many helpful comments.

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7.

REFERENCES

[1] Eisenman P versus Krier L (1989), “My Ideology is Better than Yours”, Architectural Design, no. 9-10. [2] Najjar K, Najjar R 2010, viewed 15 October, 2010, ˂http://www.najjar-najjar.com˃ [3] Wines J 2000, Green Architecture, Taschen, Köln, p. 64. [4] Van Uffelen C 2009, Ecological Architecture, Braun Publishing, Berlin, p. 152. [5] “Postfossil Ecowoodbox Kindergarten”, in Phaidon Atlas of 21.st Century World Architecture, Phaidon, London 2008, p. 424. [6] Despang M 2007, viewed 10 October, 2010, ˂http://www.despandarchitekten.de˃ [7] Callebaut V 2008, viewed 17 October, 2010, ˂http://www.vincent.callebaut.org˃ [8] Riddel R 2010, viewed 12 October, 2010, ˂http://www.rara.net.au˃ [9] Laboratories for the 21st Century: Best Practices 2003, viewed 17 July, 2010, ˂http://www.labs21century.gov/pdf/bp_daylight _508.pdf˃ [10] U.S. Department of Energy Solar Decathlon 2010, viewed 15 October, 2010, ˂http://www.solardecathlon.gov˃ [11] Cornell University Solar Decathlon, Silo House, 2009, viewed 15 October, 2010, ˂http://cusd.cornell.edu/silo˃ [12] Cornell University Sustainable Design 2010, viewed 15 October, 2010, ˂http://cusd.cornell.edu˃

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DISSEMINATION OF THE BRAZILIAN CODE FOR BUILDING ENERGY EFFICIENCY LABELING THROUGH A DISTANCE COURSE IN A VIRTUAL LEARNING ENVIRONMENT Fernando O. R. PEREIRA1, Alice C. PEREIRA2, Raphaela W. FONSECA1, Fernando C. PÍRES1 , Luíza C. CASTRO1, Mary A. YAMAKAWA1 1 Labcon – Laboratory of Environment Comfort, Federal University of Santa Catarina, Florianópolis, Brazil* 2 HiperLab– Hypermedia Laboratory, Federal University of Santa Catarina, Florianópolis, Brazil* ABSTRACT: The Energy Efficiency Quality Level Technical Regulation of Commercial and Public Services Buildings - RTQ-C is an evaluation mechanism to classify the level of energy efficiency of buildings, developed in response to the Brazilian Policy for Conservation and Rational Use of Energy. It is recognized that the effects of such a regulation on improving the sustainability of the built environment in Brazil can only happen through building design decisions. Accordingly, this article describes the development of a distance learning course, mediated by virtual learning environment, aiming to disseminate the process of Building Labeling, based on RTQ prescriptive method. The course was created in an environment called Virtual Learning Environment in Architecture and Design (VLE-A). Contents are available through hyperbook, and are divided into seven teaching units and the course is expected to last for eight weeks. The virtual learning environment represents an important opportunity for additional training to students and professionals, reaching a large number of people and effectively promoting the knowledge dissemination about the guidelines for applying the energy efficiency regulation. Several classes are in progress and it is expected to contribute for the professionals updating and to ease the development of voluntary labeling of the energy efficiency level in commercial and public services buildings. Keywords: distance learning, virtual learning environment, energy efficiency, building labeling

1. INTRODUCTION The Energy Efficiency Quality Level Technical Regulation, also called as the Code for Building Energy Efficiency Labeling is the evaluation mechanism for classifying the energy efficiency level of buildings. It was created in 2001 through the Law No 10.295, which introduces the National Policy for Conservation and Rational Use of Energy [1]. Initially, it was created the Energy Efficiency Quality Level Technical Regulation for Commercial, Services and Public Buildings (RTQ-C) and its complementary documents, such as: Regulation for evaluating the Conformity of the Energy Efficiency Level and the Manual for applying the regulation [5]. The RTQ-C aims to qualify and quantify the electric energy consumption of buildings in Brazil and was launched in 2008 by Eletrobrás, the major company in the electric energy sector in LatinAmerica and controlled by the Brazilian government. The proposal is to specify the technical requirements and the methods for classifying commercial, services and publics buildings according to its energy efficiency. It is expected that the regulation helps reducing the energy consumption by demanding a minimum energy efficiency level, which is evaluated through prescriptive or simulation methods. The creation of an energy efficiency label to be used in new buildings is an initiative that can help

consumers to demand more energy-efficient buildings than the minimum required by regulation and more savings in operational costs. The regulation covers three aspects of the buildings: the envelope, the artificial lighting and air conditioning systems [5]. Considering the relevance of such regulation, the Laboratory of Environmental Comfort/ARQ/UFSC in association with the Hypermedia for Learning Environment Lab/EGR/UFSC, have developed a distance learning course as a contribution for disseminating the knowledge for the application of regulation guidelines. The distance course was the chosen medium for the task due to the new challenges presented by technological, organizational and management transformations, in particular in educational institutions. The Distance Education (DE) is a teaching method that uses a particular way to generate, promote and provide conditions for learning. The differential aspect is the media coverage of relations among teachers and students. Essentially, this means replacing the conventional relationship for one in which teachers guide students through information and non-conventional situations, spaces and times that they do not share [4]. Although it is not a recent theme, it has gained new impetus from the current technological advances, provided mainly by information and communication technology.

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Given the continental dimensions of Brazil, DE helps promote social integration and disseminating knowledge [3]. The teaching-learning process has the potential to become more active, dynamic and personalized through Virtual Learning Environments (VLEs). These media, in evolution, use cyberspace to promote distance interaction and collaboration among the actors of the educative process and the interactivity with the content to be learned [6]. Besides are increasingly being used in the academic and corporate fields as a technological option to meet the educational demand. One of these environments is the Virtual Learning Environment in Architecture and Design (VLE_AD), being developed by the Laboratory of Hypermedia for Learning Environments for (Hiperlab/EGR/UFSC), since 2002 [7]. So, the process of labeling buildings takes the advantage of the ability to disseminate information of distance education as an instrument to bring this knowledge to the most distant populations.

2. OBJECTIVE This paper aims to describe the development of a distance learning course based on a virtual learning environment in order to disseminate the process of labeling energy efficiency of buildings. The course is based on the Prescriptive Method of the Energy Efficiency Quality Level Technical Regulation for Commercial, Services and Public Buildings (RTQ-C).

3. METHODOLOGY 3.1. Processing course development The course was developed through the Virtual Learning Environment in Architecture and Design (VLE_AD). Its content was prepared following recommendations from Contextualized Instructional Design field. It is organized in modules and explores the virtual tools to create learning situations where students have the opportunity to build their own evolutionary process. The main structure of the course consists of a set of hyperbooks1, which contains theoretical material, definitions and concepts, practical examples and exercises. The process of preparing the material in the VLEAD involved a multidisciplinary team effort, formed by professionals from different fields of knowledge. The team worked closely integrated so that was guaranteed consistency between strategies and the final product. Among the professionals involved in the elaboration of didactic material stands out: 1

Hyperbook is a mean to produce and broadcast content. Like a book, is organized by pages, chapters and subchapters, but brings from its digital nature the opportunity to follow nonlinear paths and has many natural web resources, such as, links and animations. Through it, content and activities can be organized and made available in a practical and functional way to users (PIRES & PEREIRA, 2009).

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architects and undergraduate students, graphic designer, programmer and educator. The methodology was divided in six steps: I. Understanding the regulation RTQ-C: this was done through readings, workshops and training with the several procedures included in the building labeling regulation. An overall understanding of the material was fundamental for every people in the team. II. Dominating the VLE-AD: several short courses were offered and regular meetings have been realized by the Hiperlab in order to support the team to getting acquainted and to dominate the virtual learning environment (http://www.avaad.ufsc.br). III. Producing and organizing the course material: initially, the regulation content was split in three parts: building envelope, lighting system and HVAC system, and each part was assigned to a small group of members team. Each group was in charge to develop didactic material, which consists of the theory and the several exercises for content fixing and for student evaluation. All the material was revised by two team members, who were trained in the regulation during special facing courses offered by Eletrobrás, the Brazilian company in the electric energy sector responsible by the application of the regulation. IV. Inserting the course material in the VLEAD: to enter all the material developed in VLE-AD was essential the assistance of Hiperlab for the hyperbook programming and creation. Given the large volume of material, the members from LabCon were trained to assist in this procedure. The theoretical material has been inserted into hyperbooks and interactive exercises on the course main page; as well as forums for questions, access links to additional information and the videos. Pedagogical orientation was important at this stage; V. Visual and graphic development: animations and graphic design, including icons, exercises and the hyperbooks were done by a graphic designer. VI. Pilot course application: a pilot course proved to be an important step in order to test the whole system, check bugs and train the tutorial activity.

4. RESULTS ANALYSIS 4.1. EtiqEEE Course Structure The course has a loose structure in order to allow the participant to follow their own path and rhythm of work (see Figure 1).

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 2: Hyperbook EtiqEEE – First words.

Figure 1: EtiqEEE Course front page.

The course program has been divided into 7 units, detailed as follows: Unit I – Getting familiar with the Virtual Environment, Energy Efficiency and Sustainability: In this unit the student will have a time to focus and to master the virtual environment and to have access to general information on the topic of Energy Efficiency and Sustainability. The content is mainly arranged in the form of texts and videos; Unit II – Definitions, Symbols and Units: basic concepts and terms used by the regulation are addressed in this unit. It can be accessed by the student in every hypertext chapter by using a link at the right side of the screen; Unit III – Introduction: this unit addresses the basic information available in the RTQ-C document; Unit IV – Envelope: addresses basic information related to the building envelope evaluation in RTQ-C; Unit V – Lighting System: addresses basic information related to the artificial lighting system evaluation in RTQ-C; Unit VI – Air-conditioning System: addresses basic information related to the air-conditioning system evaluation in RTQ-C; Unit VII – Applying the Regulation: this unit shows information on how to produce the final determination of energy efficiency, and the procedure for obtaining the label. Ends with an exercise and a questionnaire to evaluate the course and the accompanying tutors The content has been divided into two hyperbooks, both being developed in the Moodle platform, organized as e-books, with pages, chapters and sub-chapters. The first hyperbook, "EtiqEEE - First words," is available in the initial topic and contains basic information about the course, such as: the origin of the course, objectives, participants, methodology, evaluation and timetable (see Figure 2).

The second hyperbook, "Regulation EtiqEEE" has its information divided into 6 parts, according to the distinct study stages: initial definitions, introduction, building envelope, artificial lighting system, air conditioning system, and energy efficiency and its determination. Its access will only be released to students enrolled on the course (see Figure 3).

Figure 3: Hyperbook EtiqEEE – Regulation.

All units have specific links to access the second hyperbook, as well as the videos, background materials, forum questions and exercises related to each theme. The icon with the example building is also available in all hyperbooks in order to ease users' access. The exercises and activities were planned in different ways to keep the student motivation. Were used both playful exercises, e.g.: crosswords (see Figure 4) and single choice questions (see Figure 5), True or False or numerical calculations

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Figure 6: Building example.

Figure 4: Crosswords exercise.

Figure 5: Objective question.

For a better understanding of the concepts and calculations presented in the examples throughout the course, a model of a building example was developed. It is a building of shops and office activities, with a total area of 1000 square meters distributed in four floors. It has a rectangular shape and facade in red and white, with reflectances of 50% and 80% respectively. Its front facade is oriented to the south and the building is located in the city of southern Brazil. The building is available in the second hyperbook and can be viewed through a video and drawings (plants, elevations and views). The example building is also used to solve some exercises for the topics of the envelope, lighting system, air conditioning system and final application (see Figure 6)

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4.2. EtiqEEE course methodology The course is designed accordingly to the following methodology: The first unit of the course is to familiarize the student with the Virtual Learning Environment in Architecture and Design; The introduction to the subject of study is conducted through videos and texts related to the subject; The course content follows with six units, which can be accessed randomly or progressively driven by course schedule; In each unit, the contents are exposed through hyperbooks that contains theoretical material and practical examples, besides definitions and concepts; Additional material, such as texts, videos, links and forums are available at any time; At the end of each unit the student should apply the content covered in exercises in order to steady the concepts studied and have their performance assessed; The assessment is based on exercises that can be redone as many times as it is convenient; During the course, the users are encouraged to make brief reports of their learning and point out the aspects considered relevant; Students who have doubts about the content displayed can send their questions to the forums opened for each topic; tutors will be answering them within 48 hours. Learner assessment is continuous and interactive through the proposed activities on each topic. Students who complete the course within the prescribed period and achieve a minimum score of 70% will receive a certificate of approval of the course. The course is developed to be followed in distance mode. The expected duration is approximately 8 weeks, with a dedication average of 6 hours per week, resulting in the total of 48 hours. However, interested participants can do in less time, either by a greater dedication, or by an improved performance (see Figure 7).

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 7: Schedule for course duration.

4.3. Pilot Course The pilot course was scheduled to test the developed material. It was initially designed to last for five weeks, but due to some problems in the AVAAD platform was necessary to extend the deadline for 8 more weeks. The first group, consisting of 15 persons, was selected among graduate students, postgraduate students and also teachers, so that they could contribute and evaluate the course. Upon course completion an evaluation was conducted for necessary improvements and adjustments. The tutoring was developed by the whole course development team, having to relay the tutors in order to ensure that all questions were answered within 48 hours. It should be noted that the tutoring of regular courses should be made by persons with appropriate knowledge of the RTQ-C and specially trained in the context of the EtiqEEE course. The results have shown that the initially proposed deadline for completion of the course (6 hours / week) is appropriate, providing conditions for students with different levels of knowledge on the subject are able to develop it. The proposed exercises have been solved satisfactorily by the students when looking at the aspect of understanding the content. However, there were small problems of programming in the assembly of some exercises, which were solved by the team as they were identified.

5. CONCLUSIONS This work points to the use of virtual learning environments as a complement to training students and professionals, regarding building energy efficiency. More specifically, the distance learning course EtiqEEE – mediated by VLE-AD, can effectively reach large numbers of people and promote the knowledge dissemination about the guidelines for applying the energy efficiency regulation. The training and upgrading of professionals should create conditions for the development of voluntary labeling of the level of energy efficiency of commercial and public services buildings

It is worth mentioning that each time the course is offered, it is performed a complete evaluation in order to give a feedback for a continuous improvement process. Finally, the development of a distance learning course in an online virtual learning environment, requires a significant financial and team effort, especially generating teaching materials and developing high quality virtual environments. However, in a medium and long term, the cost is significantly reduced when one considers the reduced need for physical infrastructure and displacement of either teachers or students, and the possibility to offer the course to a large number of people and / or getting sponsor institutions.

6. ACKNOWLEDGEMENTS To CNPq and Eletrobrás for financial support. And for those who took part in the course development.

7. REFERENCES o

[1] BRAZIL. Law N 10295, 17th of October of 2001. Provides for The National Policy for Conservation and Rational Use of Energy (in Portuguese). The Government Gazette, Brasília, 2001a. Available in: . Accessed in: 20/03/2008. o [2] BRAZIL. Act N 4.059, 19th of December of 2001. Regulates the Law no 10.295 (in Portuguese). The Government Gazette, Brasília, 2001b. Available in: . Accessed in: 20/03/2008. [3] LIBRELOTTO, L. I. & FERROLI, P. C. M., Distance learning and sustainability: a proposal for ENSUS (in Portuguese). ENSUS: II Conference on Sustainability in Design. Vale do Itajaí, 2008. [4] LITWIN, E., Distance Education (in Portuguese), Ed. Artmed, Porto Alegre, 2001, 100p. [5] MINING AND ENERGY MINISTRY. The Energy Efficiency Quality Level Technical Regulation of Commercial and Public Services Buildings RTQ-C (in Portuguese), 2009. Available in: . Accessed in: 03/09/2009. [6] PEREIRA, A. T. C., SCHMITT, V., DIAS, M. R. A. C. Virtual Learning Environments (in Portuguese) Ed. Ciência Moderna. Rio de Janeiro, 2007. [7] PIRES, F. C., PEREIRA, A, T. C. The multiple functions and possibilities of a VLE: an experience with the VLE-Architecture and Design (in Portuguese). CONAHPA – National Congress of Learning Hypermedia Environment, Florianópolis, 2009.

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Actively Teaching Passive Heating & Cooling Thomas A. Gentry1 1

University of North Carolina at Charlotte

ABSTRACT: Thirty years ago, interest in passive heating and cooling briefly moved into the mainstream of American culture and the curricula of architectural education because of two separate energy crises; however, this interest all but disappeared by the end of Ronald Reagan’s first term as president. Recently, interest in the subject reappeared with increasing concerns about the environmental impact of buildings. What is significant for architectural education is what happened in the years between the mid 1980s and the recent past. During this period most architectural programs in the United States provided limited, if any, instruction on passive heating and cooling; and, the majority of architecture faculty members teaching today received their education and developed their specialties. This has resulted in architecture programs across the United States facing the problem of how to include passive heating and cooling into their curricula. Getting faculty members who lack a working knowledge of the subject to integrate it into a core curriculum is difficult. Relegating the subject to a few faculty members to teach in a collection of courses outside of the core curriculum diminishes the influence of the subject in the curriculum. This paper outlines a solution to this dilemma. Keywords: passive solar, passive cooling, teaching

1. INTRODUCTION In the 1970s, the United States experienced two energy crises when the supply of oil from the Persian Gulf region was disrupted. In response to these events, President Jimmy Carter (1977 - 1981) promoted the development and utilization of solar energy as one means for reducing the country’s dependence on foreign oil. As interest in passive solar heating developed in American culture so did the availability of books on solar architecture. Titles like, Designing & Building a Solar House: Your Place in the Sun by Donald Watson (1977), and The Passive Solar Energy Book by Edward Mazria (1979) were readily available in neighborhood bookstores. In the world of academia, the design of solar buildings was being incorporated into architecture curricula. Simply stated, the country was on the verge of having solar energy become a primary energy source. But, early in his first term in office (1981 - 1985), President Ronald Reagan redirected public attention away from solar energy and the transition never occurred. Today, interest in solar energy is on the increase once again; however, this time it is just one facet in a multi-faceted environmental agendum.

Architecture, and Progressive Architecture. In 1978 Progressive Architecture published 20 articles on the subject, which equals the number of articles all three journals published from 1981 to 1985, and surpasses by six the number of articles published from 1986 to present. It is worth noting that interest in passive solar in the late 1970s was spurred by federal tax credits and rebates; whereas, increasing natural gas prices due to deregulation sustained the interest through the early 1980s. Today, most of the articles published focus on solar electric (photovoltaic), rather than solar thermal.

2. SKILL SET SCARCE IN ACADEMIA In the 30 years between the presidency of Jimmy Carter and today, two events have occurred in academia that have made the skill set for designing solar architecture scarce. 2.1. Interest in Passive Solar Spiked In the United States, interest in passive solar peaked in the late 1970s, waned by the mid 1980s, and is to this day limited. This is reflected in the number of articles about solar thermal that have appeared in the leading architectural trade journals of the past three decades – Architectural Record,

Figure 1 - Thermal Solar Articles

2.2. Faculty Turnover & Specialization Given that young graduates from masters and doctoral programs reach retirement in roughly 40 years, three-quarters of college faculty teaching today began their careers after interest in passive solar peaked, assuming the age distribution among the faculty is uniform. Couple this with the fact faculty specialize in a wide range of subjects, of which passive solar is just one, and the reality is that

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significantly more than three-quarters of the faculty teaching today have had no, or only limited exposure to passive solar design. This is a critical problem in architectural education because faculty charged with teaching environmentally sustainable design routinely neglect passive solar design in favor of systems they perceive as easier to access. Case in point, under the pretence of environmentally sustainable design students are routinely allowed to pursue solutions that make extensive use of photovoltaic arrays but contain no passive solar heating. The question that seldom gets asked is, “When you have a heating load, why are you using a system that utilizes less than 20 percent of the solar energy falling on a given area when passive solar heating can utilizes 80 percent of the solar energy falling on the same area?”

3. CIRICULAR DILEMMA As architecture programs across the United States increase their efforts to teach the design of environmentally sustainable architecture the question of how it is manifested in the curriculum becomes more difficult. It is particularly true for subjects that offer a rich set of interlacing strategies, like passive heating and cooling. Getting faculty members who lack a working knowledge of the subject to integrate the information into the core curriculum is difficult. Relegating the subject to a few faculty members to teach in a collection of courses outside of the core curriculum diminishes the influence of the subject in the curriculum. What is needed is a rudimentary method for designing passively heated and cooled building that can be easily mastered by faculty and students.

4. RUDIMENTARY METHOD The balance of this paper outlines one rudimentary method that can be easily mastered by faculty members with a limited working knowledge of designing with passive heating and cooling. The method first inventories all the strategies, by mapping them within Earth’s energy budget. Next, it prioritizes the viable strategies. Finally, it identifies the various systems available for executing each of the chosen strategies. With this information in hand the design process proceeds much as it normally would to produce designs that are richer and more environmentally sustainable. 4.1. Inventory the Strategies While there are many good resources available for learning about the details of passive solar heating and passive cooling, what is missing is a graphic resource that provides an overview. Imagine being unfamiliar with the overall shape of Europe and the arrangements of the countries. Now imagine what it would be like to construct in your mind the shape of Europe and the physical relationships between each country having only individual country maps, or worse yet, text only descriptions. Lastly, imagine what it would be like to plan a trip with several destinations scattered throughout Europe. Designers who do not have a good understanding of passive solar heating and passive cooling face a similar situation. Without a clear overview of the various routes for reaching their destinations the paths they chose are often suboptimal. For this reason the author developed a map – a chart.

Figure 2 - Passive Heating & Cooling Chart (Actual chart is 48” x 30” and in full color)

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Predicated on Earth’s energy budget, the chart is subdivided into three horizontal bands, with the top band representing the space of the universe, the middle band representing Earth’s atmosphere, and the bottom band representing all the terrestrial substances of Earth, including plants, animals and people. The Sun is the primary energy source, space is the primary energy sink, and the atmosphere and Earth are secondary sources and sinks. Using arrows that are proportional, the chart inventories all the paths for energy to flow from the sources to the sinks; and, it explains the physics that drives the flow and how the flow can be manipulated. The chart also graphically represents the how solar and terrestrial radiation, air temperature and movement, and moisture effect thermal comfort. With this information, a designer can understand the energy relationships of passive heating and cooling much in the same way a map of Europe allows a traveler to understand the spatial relationships between countries and cities. But, just as the map is not a travel plan, the chart is not a design program. The traveler must first select the destinations, and the designer must prioritize the strategies. 4.2. Prioritize the Strategies One of the easier ways to prioritize passive heating and cooling strategies is to plot on a psychrometric chart with expanded comfort zones the daily temperature and relative humidity for multiple days throughout the year. Two well established tools for doing this are:  The psychrometric chart in, Design with Climate: Bioclimatic Approach to Architectural Regionalism by Victor Olgyay, (Reprints of the chart are available in, Mechanical and Electrical th Equipment for Buildings, 11 Edition by Walter Grondzik and others, The Architect’s Portable Handbook, 2nd Edition by Pat Guthrie, and several other texts.) [3, 4]  The interactive computer psychrometric chart in Climate Consultant 5.0 developed by the Department of Architecture and Urban Design at the University of California, Los Angeles. (Figure 3 shows a screen shot of the chart produced in Climate Consultant 5.0 for Chicago, Illinois.)

Figure 3 - Climate Consultant 5.0 Psychrometric Chart

One of the advantages of the plots produced in Climate Consultant 5.0 is they list the percentage of the time and the number of hours for the period being modeled that each design strategy is feasible. For example, in Chicago, Illinois natural ventilation is an effective cooling strategy for 11.1 percent (970 hours) of the year. Prioritizing the various strategies is just a matter of ranking them from most to least effective. Once the strategies have been ranked is possible to determine which are appropriate for the specific project. Getting back to the travel analogy, it is like ranking destinations for a tour based on information obtained from a guide book. Once the destinations have been selected it is possible to determine how many are viable within the schedule and budget. 4.3. Identify the Systems There are multiple systems for implementing each passive heating and cooling strategy. For example, natural ventilation can be implemented using wind induced ventilation or stack effect ventilation; but, wind induced may be more appropriate for one project while stack effect is more appropriate for another project. This is where the skill of the designer is tested. A good designer has an extensive catalog of systems to draw from and tools for analysis. Resources for cataloging systems include precedence studies and books such as, Climatic Building Design: Energy-Efficient Building Principles and Practice by Donald Watson and Kenneth Labs. Fortunately, these types of resources are easily shared, so faculty and students who are just learning to design with passive heating and cooling are only limited by the number of systems they become familiar with. With programs like Ecotect and DesignBuilder being relatively easy to learn, the most commonly used tool for analysis is computer simulation; however, physical modeling and onsite data collection are still invaluable tools that should not be overlooked. One of the more reliable and easier physical modeling tools to use is a sun chart/protractor, like the one shown in figure 4. Used in conjunction with a physical model, a designer can accurately and quickly assess solar gain throughout the year.

Figure 4 - Climate Consultant 5.0 Sun Chart

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Continuing with the travel analogy, being able to identify as many systems that can fulfill each strategy is analogous to knowing several methods for reaching each destination. Relying solely on automobile transportation to reach every destination may limit the richness of the tour, given that travel by air reduces the time between destinations, travel by rail accommodates sightseeing and socializing, and travel by bicycle enriches the experience of place. With multiple modes of transportations, a guide book to identify destinations, and a map to relate the destinations to one another, it is possible to plan a truly enjoyable tour. With multiple systems for implementing passive heating and cooling strategies, analysis tools to prioritize of strategies, and a chart to relate the strategies to one another it is possible to produce a richly developed design.

energy. Strategies for enhancing the transfer of thermal energy from the house to the atmosphere include direct evaporative cooling, high thermal mass with night flushing, and natural ventilation. There is also the opportunity to transfer thermal energy directly from to house to space by increasing the emissivity of the surfaces oriented towards space. Looking at the psychrometric chart to prioritize design strategies the order is: 1. Sun shading, 2. Evaporative cooling, 3. High thermal mass w/ and w/o night flush, and 4. Natural ventilation. Using these strategies will provide thermal comfort for more than a third of the year.

5. EXAMPLE The task is to design a passively cooled house for Tucson, Arizona. Looking at the chart there are numerous strategies for cooling. Shading and the use of high albedo (solar reflectance) materials are two defensive strategies for reducing solar radiation. Mass effect cooling is a strategy that uses terrestrial substances as secondary sinks to draw off thermal

Figure 6 - Tucson Design Strategies [5]

Figure 5 – Cooling portion of chart

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Possible systems for sun shading include ramadas (shade structures) and vegetation. Two methods for enhancing the performance of the ramadas is to use high albedo materials to reflect solar radiation away from the house, and to provide an open configuration to prevent heat from accumulating underneath. While two stage evaporative cooling can provide more hours of cooling than direct evaporative cooling, the number of direct evaporative cooling systems is greater. Two stage evaporative cooling is limited to mechanical systems, but direct evaporative cooling includes misting, fountains, plant transpiration, as well as mechanical systems. The use of high thermal mass dates back to earliest human settlements in the region, with earth and stone being the dominant building materials. These materials are still viable today, as well as brick, concrete, containerized water, and phase change materials (PCMs). Natural ventilation comes in fourth on this list of four, but still it provides thermal comfort for more than a tenth of the year. When it is coupled with high thermal mass in the form of night flushing it provides additional hours of thermal comfort. There are several systems available for natural ventilation –

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

wind induced cross ventilation of interior spaces using windows with and without wing walls, wind enhanced ventilation of outdoor living spaces with building openings, thermal chimneys, and wind towers. Many of these systems can be coupled with direct evaporative cooling systems to provide greater thermal comfort. Knowing what systems are available to implement the appropriate strategies, and knowing how the strategies relate to one another, it is now possible to move forward in the design process to address all other issues while producing a more environmentally sustainable solution.

6. CONCLUSION The majority of architectural faculty members teaching design studios today lack the insight to teach passive heating and cooling, but choosing to relegate the teaching of passive heating and cooling to non-studio courses that are taught by a handful of knowledgeable faculty members does not give the students the opportunity to fully explore the subject. The only satisfactory solution is to give all faculty members the resources they need to adequately teach the subject in the studios; and, to have the more knowledgeable faculty members advance the students’ understanding of the subject with nonstudio courses. The required resources for the full faculty are: 1. The chart, “Passive Heating & Cooling: Managing Energy in Microclimates & Buildings” to develop a good overview and to provide an inventory of all of the possible design strategies. 2. A psychrometric chart showing the expanded comfort zones associated with each passive and heating and cooling strategy to help prioritize the design strategies, and 3. An extensive catalog of systems to draw from and tools for analysis. With these three resources and a limited amount of instruction every faculty member can take an active role in teaching passive heating and cooling.

7. REFERENCES [1] Watson, D. Designing & Building a Solar House: Your Place in the Sun. Garden Way Publishing: Charlotte VT, 1977. [2] Mazria, E. The Passive Solar Energy Book. Rodale Press: Emmaus, PA, 1979. [3] Olgyay, V. Design with Climate: Bioclimatic Approach to Architectural Regionalism. Princeton University Press: Princeton, NJ, 1969. [4] Grondzik, W. Mechanical and Electrical Equipment for Buildings, 11th Edition. John Wiley and Son: New York, NY, 2009. [5] Climate Consultant 5.0, Department of Architecture and Urban Design University of California, Los Angeles.

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Sustainability Indicators in Buildings Identifying Key Performance Indicators Lone FEIFER1 2 1

Aarhus School of Architecture, Aarhus, Denmark 2 VELUX Group, Hoersholm, Denmark

ABSTRACT: What makes a building sustainable, or green – and how is the one better than the other? This paper aims to investigate a method on how to identify a sustainable building in an overview, looking into possible measures and targets by method of performance indicators as a benchmark system. Is it viable to obtain a result which can be communicated on several levels, also to decision makers being laymen? A common understanding of indicators system and terminology within sustainable construction could form a platform for navigation and communication of degrees of sustainability. An investigation of the categories and indicators of the upcoming international standard CEN TC 350 is performed. A methodology is elaborated into a system and with an output usable for levelled communication, thus sourcing a common awareness of sustainability in the particular building. As illustration, indicators are set up in an overview, and a case study is performed. . Keywords: Key performance indicators, communication, stakeholders, triple bottom line

1. INTRODUCTION Buildings represent a major troubleshooter in regards to solving the imminent task of decreasing carbon emissions. Consuming more than 40% of the energy spent in industrialized countries, the building sector is an obvious place to look for leverage on the threepart challenge to minimize energy consumption and carbon emissions, secure political independency of energy availability and create economical growth through incentives and innovations in the building sector. Buildings are not consumers of energy - the users of buildings are. Who are these consumers, and thus the stakeholders? The stakeholder landscape when discussing buildings is very broad, with multiple interests, some private interests, some professional, some short-term, some long-term, all depending on the individual approach. There is one overshadowing common interest for all, namely the public interest of leveraging the huge potential of buildings into a tool solving some of the global challenges. This paper seeks to investigate which indicators are available to count and account for sustainable buildings, for the public stakeholder in this matter. The approach taken is deliberately banal, inspired by the Albert Einstein citation “you do not really understand something unless you can explain it to your grandmother”. If we are going to be able to address and handle the challenge, we need common denominators that can be understood and handled by peers, professionals, policy makers, politicians and the public in general. Today all designs are sustainable and with environmental focus – at least allegedly. Ever since green became the new black, the building sector is as struck by the desire to go green - and the claim to be sustainable has become as well a claim to fame. The term “green” is in substantial risk to become a

mainstream hygiene factor, addressing the subject only on a superficial level, and not necessarily reflecting the long-term effects or actual impacts. Is there today such a thing as a public common denominator within indicators of sustainability? This paper wishes to investigate and discuss appropriate tools, knowledge and awareness for ordering, expecting and using sustainable buildings, as well as discuss the motive of sustainability as such.

2. INDICATORS OF TODAY 2.1. Terminology – green and/or sustainable A green building covers measures like limiting consumption of non-renewable fuels, water, land, materials, emissions of greenhouse gas and other emissions; minimizing impacts on site ecology, solid waste or liquid effluents, improving indoor air quality, natural lighting and acoustics and securing maintenance of performance. A sustainable building features all of the same measures, and in addition addresses longevity, adaptability and flexibility of the object, accounts for the efficiency of resources spent, addresses safety and security, includes social and economic considerations and regards urban and planning issues [1]. Sustainability is the capacity to endure, to sustain. In regards to ecology, the term describes how biological systems remain diverse and productive over time, examples of sustainable biological systems are long-lived and healthy wetlands and forests. In regards to humans, sustainability is the potential for long-term maintenance of well being, which has environmental, economic, and social dimensions. So when discussing buildings, the core issues are long-term maintenance and well being of the users, seen under the aspects of environmental, economic, and social dimensions.

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2.2. Dimensions, standards and schemes Environmental, economic and social dimensions are used as protection components of sustainable development introduced at the first Conference of the Parties (COP) in Rio 1992 [2]. These three dimensions are subsequently used as interdependent and mutually reinforcing pillars of sustainability. An approach agreed by the ICLEI – Local Governments for Sustainability in 2007 uses the “Triple Bottom Line” - also known under the abbreviation of TBL or 3BL. The dimensions of environmental, economic and social are popularised into "people, planet, and profit". The TBL uses the very same pillars in the attempt to capture an expanded spectrum of values and criteria for measuring organizational (and societal) success: economic, ecological and social. The Technical Committee CEN/TC 350, under the EU Commission, is preparing a suite of standards for a system to assess buildings using a lifecycle approach, known as “Sustainability of construction works”. The standards provide principles, requirements, methodologies and calculation rules for the environmental, economic and social performance of buildings taking technical characteristics and functionality of a building into account. The series of standards aims for the assessment of environmental, social and economic performance of a building, to be made on an equal footing, on the basis of the same technical characteristics and functionality of the object of assessment. The standards are not yet released. Performance Indicators are quantifiable performance measurements used to define success factors and measure progress toward the achievement of business goals. The measures are typically referred to as KPIs (Key Performance Indicators and used within a balanced scorecard as a method of consolidations. A comparison between the two main European assessment schemes, DGNB and BREEAM within the three dimensions, outlines that the priority and weighting from one scheme to another can be substantially different [3]. One calculation tool for assessments, the iisBEE calculation tool [4], overcomes national barriers by refraining from the use of absolute values, leaving this up to the final users to discuss and implement. The tool is opensource and global, with an approach to meet different ambition levels within sustainability – from 0 as acceptable practice to 5 as best practice. Each project using this tool can discuss and assess which level is to be met, and in the final output see this reflected in 7 performance categories. Some of the categories are close to the TBL dimensions also used in the CEN/TC 350, however split further into categories, and the aspect of culture and heritage has been added.

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2.3. Illustrative field study Two British researchers - H. Alwaer and D.J. Clements-Croome [5] performed a field study on key performance indicators in assessing sustainable intelligent buildings. The research made first a study on identifying the key issues related to sustainable intelligent buildings (environmental, social, economic and technological factors) and to develop a conceptual model for the selection of the appropriate KPIs; secondly the research performed a critical test to stakeholder’s perceptions and values of selected KPIs intelligent buildings. 20 stakeholders of the construction industry were invited to review and score the 115 individual indicators. The indicators were derived from the most frequent UK systems (BREEAM, DQI, SPeAR), supplemented with major international schemes (LEED, CASBEE, AIIB, SBC and HK-BEAM), and additional indicators related to health and well being and their effects on productivity and well being of users, as well as automation, intelligence and user control of the indoor environmental quality, air quality, temperature, daylighting and sound in the buildings were included. In order to test an objectively optimal model, the researchers developed a conceptual Sustainable Built Environment Tool, which was then tested in practice on the very same stakeholders.

3. INDICATORS OF TOMORROW 3.1. A levelled approach Is it possible to outline a set of common denominators which can serve as a future basic KPI tool? The assumption is tested on the general principles of sustainability in building construction described in ISO 15392:2008. The objectives of an assessment being: to determine the impacts and aspects of the building and its site, and to enable the client, user and designer to make decisions and choices that will help to address the need for sustainability of buildings [6]. The basis of the study is formed by the CEN TC 350 standards, using the structure of TBL in combination with the LCA principle [6d]. The - not yet released - standards outline content and a set of suggested framework indicators for environmental performance [6b], social performance [6c] and economic performance [6d]. The framework of the three dimensions in a brief outline: Economical dimension contains four general indicators, covering the cost of a building up front and seen over years, maintenance and costs for operations, suitability for conversions and number of refurbishment cycles. The social dimension covers five indicators, mainly the impacts of a building related to its occupants, expressed by quantifiable indicators. There are 3 general indicators within the environmental dimension, limited to the assessment of environmental impacts and aspects of a building on the local, regional and global environment. The quantifiable indicators are expressed mainly as a life

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cycle assessment (LCA) and with some additional quantifiable environmental information.

Settler´s House, was matched against the suggested CEN/TC 350 indicator scheme system.

The indicators have a further level of information and grouping around the indicators – from 1 to 15 different numbers. The values of each informative indicator add up to the general indicator level. See Table 1 for example on one category.

As basis for the environmental assessment, the report on LCA from TU Darmstadt was for the environmental impact category [7], for the other informative indicators the general project information was the outline. The values used in the scheme are subjective and based on a very general assumption of practice parameters. The social and environmental categories are exemplified in figures 1 & 2.

Table 1: Setup of the Environmental indicators and informative indicators

Indicator

Environmental Impacts

with

Informative Abiotic depletion potential Acidification of land and water resources; Destruction of the stratospheric ozone layer; Eutrophication; Formation of ground-level ozone; Global warming potential; Use of non-renewable primary energy; renewable primary energy; secondary materials; secondary fuels; freshwater resources

Resource Input

Additional Environmental Information

Category

Components for reuse; Materials for recycling; Materials for energy recovery; Non-hazardous waste to disposal; Hazardous waste to disposal ; Radioactive waste to disposal Exported energy

The output of the score is a radar / spider web format, used in several assessment schemes e.g. DGNB, SPeAR and iisBE Tool. . 3.2. Case study

4. RESULTS The results of the various schemes and scales show a large variation. Some focus on a single indicator, leaving out the long-term consequences, some refrain from considering the expected service life. The research paper by Alwaer and ClementsCroome [5], which first groups the indicators of main schemes, and then test a conceptual model with broad indicators, evidently shows, that categories and indicators turn out with very different weightings, even amongst peers placed in the same skill group. Different individuals of the same skill group (e.g. architects) give different weightings based on their preferences and experiences of buildings. Even by taking the average between the stakeholders, the aggregated results give different weightings which could skew the final assessment results. Also, it is a clear result that the different test persons interpret the priority levels very differently and open, leading to a large variation in the assigning of scores, also within the same system [4]. The general result is a degree of inconsistency about the relative importance of different KPIs across stakeholders. The evaluations are skewed with a subjective judgement, because there is no consensus-based knowledge on the sustainability indicators. As a fact, there are very different, even contradictory estimates and views about the sustainability indicators amongst the professionals.

Finally, a case analysis was performed, where the LCA calculation of the Model Home 2020 project LichtAktiv House, a modernisation of a German

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Figure 1: Output of the indicators within the social dimension, validated from 1-5 where 1 is below current practice and 5 is best practice.

Figure 2: Output of the indicators within the social dimension, validated from 1-5 where 1 is below current practice and 5 is best practice.

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When looking into the future kaleidoscope of the CEN/TC 350 there is a suggestive outline that the overall dimensions of environmental, social and economical could become predominant as metacategories. The indicator measures for social and economic sustainability are still in their infancy, and the economical aspect is quite inactive or considered a hygiene factor in many of the projects – making it difficult to compare. Several of the informative indicators under environmental, e.g. eutrophication and acidification of land and water resources will mean very little to most professionals yet. However the idea of measuring the impact rather than the performance is the merging trend, supported strongly by the financial calculations of the added value of sustainable buildings. The CEN/TC 350 indicator analysis remains as an exercise in the garage. Mainly because standards are not released yet, the indicator sets are not finalized, still under discussion and final revision; consensus is still years ahead of us. However the picture drawn up is clear and can be used to communicate projects sustainability aspirations and benchmarks within a relative group of weights, and supports the point that a benchmark must stay simple and be able to give with different levels of overview. We may as well start using it now.

5. DISCUSSION Different people have different views and levels of understanding about sustainability issues. A standardised platform for assigning relative importance to different sustainability impacts is required if there is to be a consistent basis for decision-making [4]. The stakeholder picture within the construction business is very broad. Typically different individuals or groups are responsible for different levels within building sectors, each with their viewpoint, perspective and interest on the problems at hand, implications and solutions. Where developers could be looking for a return on investment, open towards a service life discussion linked to investment interest, quantity surveyors could regard sustainable intelligent buildings as being significantly more expensive from the outset - the difference of estimating cost or monetary value. The added value gained by being sustainable must be properly accounted for, and experience along with feedback flows can provide useful evidence for future designs. The differing views of the assessor, the building architect and the building engineer on multiplier level lead to subjective results [4] This means, that effective project value requires an ongoing dialogue between all decision makers to negotiate appropriate compromises and balance stakeholder views. Thus, by recognizing KPIs as a tool to reach consensus among stakeholders, it seems useful to discuss a procedure to do so as a future topic.

The problem with any statement, certification, assessment, assumption, and result in the field of construction is, that the minute is has been stated, the next minute, it is questioned. This is a culture and an educational discipline to put up questions as for results of sustainable buildings. So when the culture is to question any fact put up, what will remain? The subjective conviction and belief, typically driven by accumulated experience and ability to create consensus in the group, using the big storage of common knowledge. However, no indicators, performance categories and impact weightings are common knowledge yet; then it is pointless to keep developing further schemes, matrix, indicator systems and benchmarkings, without a common denominator and agreed starting point of the yardstick. By defining three levels, differentiated by complexity, communication and target groups (Table 2), the approach can be targeted according to target group. Table 2: Setup of communication levels according to target groups and corresponding complexity

Label Performance Category

Target Group

Complexity

Politicians & Public

3

General Indicators

Policy Makers & Press

12

Informative Indicators

Peers & Professionals

69

The level of detailing could follow the framework of the CEN/TC 350 standards, and be used accordingly, leaving each target group within their comfort zone and still discussing the same issue at hand. The benefit of using the CEN/TC 350 as platform is, that the particular national, private, corporate or political interests are taken care of in the one and same model, giving the overall consensus framework. If the point of departure is shared as far as the three levels, a lot of common luggage can be shared initially, still allowing for differences of opinion, but with a completely different consensus to begin with.

6. CONCLUSION The quintessence of a sustainable building is that it can ensure human wellbeing on a long-term basis. A certification or an assessment must give an assurance of physical surroundings, which will secure and maintain the wellbeing of the users. This is the main interest of the public as key stakeholder within sustainable buildings, and any attempt to bring, sell, promote or convince, legislate, pioneer, conquer, promote or demonstrate should be measured on a scale of what will matter most to the public - long-term. The decision-makers are to

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legislate the framework and have policy-makers formulate quantifications of the currency with which we can cash a future independency of fossil fuels. They are today presented with a wide range of statements and postulates – some are for real, some will work, some will not - and how will we know? We may not know before in the next generation, and even then, we need someone to investigate this, and to communicate it, and bring it into the common consensus bag of common knowledge. The economical dimension and the profit aspect are in fact the weakest dimension in terms of indicators. Public interest is that sustainable buildings stay within financial reach and social accessibility. It is highly problematic, that the financial aspect is not really a part of the discussions. This dimension cannot be left out, sustainability must, in order to mean a difference, be within social reach, and that means that it cannot only be available for the well-off private or public clients. Can you actually put a price on wellbeing, or rather on the absence of it? The consequences of a failing health, of lack of efficiency and absence of workers, early need for care, exceed surely the economical calculations of the upfront costs of constructing a sustainable building. Prevention goes above and beyond treatment, also when it comes to buildings. The successful transformation of the individual understanding into high quality indicators stands out as the dilemma, no matter the grouping and levelling of indicators and categories. Policymakers and politicians are not professionals and will never be. Therefore the construction industry should start simplifying, planners should decipher the concept of sustainable buildings, take it out of the rocket science universe and keep it simple. The most imperative need is to keep it on a simple level, as a minimum when explaining it to politicians, or to your grandmother, as Einstein said. Even though the issue is very complex, it could be concentrated to three levels by consensus. Politicians stay on top, they got time for 3 bullet points, policy makers can handle the complexity of 12 levels, and peers and professionals go all the way to the informative indicator level, where you must know your way through the 69 (and counting) indicator informatives - like acidification and eutrophication, and so forth. The grouping of performance categories and deriving indicators in the CEN TC/350 could become a common denominator, subject to be challenged and discussed, but leaning on the very same framework would mean a great difference. How the weighting and subjective assessments is made, will be a whole other challenge, which employs aspects of general education at the schools, information to the public and much more educational aspects in general, if a satisfying level of common knowledge within this field should be reached.

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Health is our maybe most precious resource, we must be sure to programme accordingly since we depend on this for future wellbeing through a healthy triple bottom line. We need grandmother to live for as long, that we have time to explain the whole issue about sustainable buildings to her, and we will then need to have our grandchildren explain us the next steps, that is, if we live that long.

7. ACKNOWLEDGEMENTS Thanks to Nils Larsson for making his work accessible and for inspiration in general, to Lars-Ove Persson for making it feasible and to Peter Lawaetz for making it possible.

8. REFERENCES [1] Larsson, N. (November 2010). Building performance assessment, SB Method and SBTool. [2] Report of the United Nations Conference on Environment and Development, R. d.-1. (1992). [3] Birgisdottir, H. (n.d.). Retrieved 12 2010, from Comparison of how the concept of sustainability is covered in Assessment Schemes DGNB & BREEAM, by Harpa Birgisdottir, SBI: http://www.dkgbc.dk/media/8958/101029_dkgbc_styregruppe _breeam_dgnb.pdf [4] iiSBE Tool 2010: http://www.iisbe.org/sbtool2010 [5] H. Alwaer, D. Clements-Croome. (2010, April). Key performance indicators (KPIs) and priority setting in using the multi-attribute approach for assessing sustainable intelligent buildings. Building and Environment # 45 (4). [6] prEN 15643 a. General Framework b. Framework for the assessment of environmental performance c. Framework for the assessment of social performance d. Framework for the assessment of economic performance e. prEN 15804: Environmental product declarations – core rules for the product category of construction products f. prEN 15978 Sustainability of construction works - Assessment of environmental performance of buildings - Calculation method [7] Manfred Hegger, T. B. (2010). Ökobilanzierung VELUX Model Home 2020 „LichtAktiv Haus“ Hamburg. Fachbereich Architektur, Fachgebiet Energieeffizientes Bauen. Darmstadt: Technische Universität Darmstadt..

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Do current environmental assessment methods provide a good measure of sustainability? Or what should be a good measure for Green Building Standard? Edna SHAVIV Faculty of Architecture & Town Planning, Technion-Israel Institute of Technology, Haifa, Israel ABSTRACT: We present the fundamental ideas, logic and thoughts that led to the definition of the requirements for an energy efficient building that warrants green points according to the Israeli Green Building Standard. Emphasis is put on the sections concerned with: Bio-climatic, Passive and Low Energy architecture of the building. This includes: The determination of the Bioclimatic and Passive solar strategies and their implementation. Design for minimal energy consumption for cooling, heating and lighting, via building envelope design optimization. Design for solar and wind rights for the proposed building, as well as the close surrounding environment: buildings and open spaces. Keywords: green building standards, passive and low energy architecture, bio-climatic design, energy rating of buildings

1. INTRODUCTION Green Architecture is today the current fashion and the main stream in architectural practice. Hence, one would expect bio-climatic, passive and low energy architecture to grow with the Green Architecture movement. However, it didn’t happen. A former paper presented in PLEA 2008 [1] examined carefully different examples of LEED accredited buildings and found that almost no improvement in the energy performance of the building was achieved. Moreover, even when energy efficiency was considered, it could be achieved merely by improving the mechanical, electrical and hot water systems. There was no need to improve the architectural design from bio-climatic and passive solar aspects. Based on that conclusion, the author of this paper, who was in charge of the revision of the Energy Chapter of the Israeli Green Building Standard, has put an emphasis on the improvement of the architectural design, i.e. implementation of bioclimatic and passive solar solutions, at each “Green grad” level. The first part of the paper summarizes what is imperfect with current assessment methods. The second part discusses the question: what should be a good measure for Green Building Standard and how it can be implemented. In the first part we focus on LEED [2] (Leading in Energy and Environmental Design) that was established by US Green Building Council (USGBC). This is because it is the most common one and therefore the momentum of the Green Building Movement in the USA, as well as worldwide, has been achieved largely through it. In the second part we demonstrate the implementation of the ideas for improving the current assessment methods for rating “Green Buildings” by the energy chapter of the Israeli Standard IS 5281 “Buildings with reduced environmental impact-Green Building”

[3] as well as by the Israeli Standard IS 5282 “Energy Rating of Building” [4]. Emphasis will be put on the energy performance issues and especially on rhe requirements for implementing passive and low energy architecture.

2. WHAT IS IMPERFECT WITH CURRENT ASSESMENTS TOOLS AND HOW CAN WE IMPROVE THEM? 2.1. Do current environmental assessments methods provide a good measure of sustainability? In general most of the environmental assessments tools like LEED or BREEAM [2,5], as well as the Israel Green Building Standard [3], provide a measure for sustainability refer to similar issues. For example: LEED NC 3.0 (2009) includes the following issues (see Fig. 1): SS- Sustainable Sites (26 points), WE- Water Efficiency (10 points) EA- Energy & Atmosphere (35 points), MR- Materials & Resources (14 points), EQ- Indoor Environmental Quality (15 points), ID- Innovation & Design Process (6 points), Regional Priority (4 points). These are all important issues that justify achieving green buildings with reduced environmental impact as well as buildings that possess good indoor environmental quality. So, what is imperfect with this approach? LEED 3.0 ID Rg 6 p 4 p 5% 3% SS 26 p 24%

WE 10 p 9%

MR 14 p 13%

EA 35 p 32%

EQ 15 p 14%

Figure 1: LEED 3.0 – total possible points

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1. Current environmental assessment methods in general use simple ‘point hunting’ approach. The tendency is to choose cheap and “easy” points in order to collect enough points to be labelled “Green Building”. The points for reducing the energy consumption of the building are, in general, not cheap nor “easy”. This means that even if one third of all possible points is assigned to energy efficiency (like in LEED), nevertheless, in order to achieve LEED Silver, the most common goal, one can get the minimum score required for it with almost no improvement in the energy performance of the building. 2. Energy efficiency in buildings, according to LEED, can be achieved only by improving the mechanical, electrical and hot water systems. There is no need to improve the architectural design from bio-climatic and passive solar aspects. 3. In LEED the use of renewable energy, like solar energy for hot water, PV, or even buying Green Power, is awarded twice: once, as it reduces the amount of the total purchased energy and again, as it contributes to the On Site Renewable Energy credit, or to the Green Power credit. However, Passive Solar Energy is not considered as On Site Renewable Energy. Consequently, there is no incentive in LEED for passive solar design. 4. The energy calculations in LEED for minimizing energy performance are based on appendix G of ASHRAE 90.1, which can’t be used for buildings without mechanical systems. Therefore, If the building is an innovative Passive Solar and Bioclimatic one that doesn’t require any mechanical heating or cooling, it can’t be assessed and graded by ASHRAE and hence, lose the points for the credit of “minimizing energy performance” by LEED. In other words, the best design fails! It might even lose the possibility of achieving Green Building accreditation, as happened to the SF Federal Building, designed by Architect Mayne [6]. If this is not a paradox, what is? 2.2. What should be a good measurement for green building standard? To overcome the above mentioned problems the following solutions may be implemented: 1. On top of the prerequisites, minimum required points for not “easy” important issues, like energy conscious design, should be imposed at each “Green Grad” level. 2. The fact that all energy saving features are all lumped together in one basket, and the energy standard are defined in such a way that the goals may be achieved with no need for good architectural design, leads to the present situation. The Building Code should treat the energy conscious building design separately from the mechanical and the hot water systems. This is because the building is designed to last for at least 50 to 100 years, while the mechanical and hot water systems last less than one 15 to 20 years. Moreover, such a separation will overcome the paradox mentioned above in point 4, as the building low energy features will be evaluated separately from its mechanical equipment whether they exist or not.

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3. Passive Solar Energy should be considered as On Site Renewable Energy and should be awarded at least as solar energy for hot water, PV, or buying Green Power.

3. THE ISRAELI STANDARD

GREEN

BUILDING

The Israel Green Building Standard ST-5281: “Buildings with Reduced Environmental Impact” was first issued on November 2005 and consisted of only one part that included Residential Buildings, as well as Office Buildings. After three years of discussions, it was decided to review periodically this standard at least every five years, in order to adapt it to scientific and technological developments. This paper refers to the revision of this Green Building Standard, as was proved by the expert committee. The revision of the Green Building Standard includes at the stage that this paper is written, three parts as follows: ƒ SI 5281 Part 1: General requirements, ƒ SI 5281 Part 2: Requirements for residential buildings, ƒ SI 5281 Part 3: Requirements for office buildings. The revision for ST 5281 Part 2 (residential) includes the following issues: EA- Energy (40 points), SS-Land (13 points), water, WE-Waste and Drainage (17 points), MR-Materials (9 points), EQ-Indoor Environmental Quality (5 points), ED-Other Environmental Issues, including: Waist, Management & Transportation (9 points), ID-Innovation & Excellence (5 points), Total: 100 points. The different between Residential and Office buildings are small. (See Fig. 2). Residential-Buildings ID 5% ED 9% EQ 4%

EA 40%

MR 9%

WE19% SS 14%

   Figure 2: IS 5281 – total possible points for residential buildings

There are 5 “Green Grades” as shown in Table 1. The number of prerequisites subjects is 15 (no points obtained for them). These prerequisites are distributed along the different issues to ensure that a Green Building must be of high quality in each of these subjects. On top of the prerequisites, the Israeli Standard required achieving a minimum number of points in key subjects like Energy (see Chapter 3.2 Table 2). Table 1: Required points for rating “Green Grades” in each level Rating of Building "Green building" Silver "green building" Gold "green building" Platinum "green building" Diamond "green building"

Total points 55 to 64 65 to 74 75 to 82 83 to 89 90 or more

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

4. THE ENERGY CHAPTER OF THE ISRAELI GREEN BUILDING STANDARD The author of this paper was in charge of the Energy Chapter of the revision of the Israeli Green Buildings Standard ST-5281: “Buildings with Reduced Environmental Impact”. The Emphasis in the suggested revision has been laid on the improvement of the architectural design, i.e. implementation of bio-climatic and passive solar solutions as well as on minimizing the energy consumption of the building. The mechanical equipments had to be rated high according to the COP of each piece of equipment. However, in order to avoid design failure from the point of view of BioClimatic and Passive Solar Architecture, all the energy saving features were handled separately. Instead, total performance requirement and available points were imposed on each of the following issues: BC-,Bioclimatic design (10 points), EC-Energy Consumption for heating and cooling (16 points), DIDaylight Illumination (3 points), RE-Renewable Energy (4 points), AC-Air Conditioning Efficiency for cooling & heating (5 points), SW-Solar Water heating (1 point), OS-Other Systems (1 point), Total: 40 points These numbers are for residential buildings. For office buildings the numbers are slightly different (Fig . 3). Energy-Residential AC 5 OS 1

BC 10

RE 4 SW 1

building designed, as well as for the reference one, are performed according to the electricity consumption of an Air-condition system, with a required minimum COP. Thus, only the architectural aspects are considered under this title. Solar systems like solar water heating, and PV, are not in group A as their life expectancy is much shorter that the building life expectancy. On top of it, Solar systems for water heating is mandatory in residential buildings in Israel for more than 30 years, so no points can be granted for it. Only in cases were it is not mandatory, solar water heating systems can be awarded points according to the size and efficiency of the system. PV is not mandatory, but as it is highly subsidized by the government, the decision was to consider it as a separate issue. The minimum required points for these two groups, to obtain the different “Green Grades” level are given in Table 2. Table 2: Minimum required points for different “Green Grades” level Rating of Building "Green building" Silver "green building" Gold "green building" Platinum" green building" Diamond" green building"

Group A 12 15 18 21 24

Group B 5 6 7 8 9

As the emphasis of this paper is put on the architectural aspects of the energy chapter of the Israeli standard, we present in details the energy related issues of group A.

5. BIO- CLIMATIC DESIGN

LE 3 EC 16

Figure 3: Energy Related issues for Residential Buildings total possible points

We defined two groups of energy related issues: Group A: Architectural aspects i.e. Passive and Low Energy Design, including: Bioclimatic design, environmental assessment (solar and wind rights) and minimizing the energy consumption of the building for heating, cooling and Natural illumination. Group B: systems of the building including: Renewable Energy, Solar Water Heating, Air Conditioning for cooling and heating, and Other Systems. As the life expectancy of a building in Israel is about 50 to 100 years and that of the systems is about 15 to 20 years only, the requirements for these two families of issues should differ and we can’t treat them on equal footing in order to minimize the energy consumption of the building. The Energy Consumption of the mechanical equipments is controlled under an Israeli Standard that defines the minimum required efficiency for each system, while the Energy Consumption of the building is carried out according to another Israeli Standard that defines the energy rating of the building. The calculations of the energy consumption for heating, cooling and daylighting for the proposed

The Bio-Climatic design includes the following subjects: a. Determining bio-climatic design strategies and applying passive and low energy design systems (12 points). b. Environmental assessment in regards to the sun and wind (1-8 points). 5.1. Determining and applying bio-climatic design strategies (1 to 2 points) The requirement is to present the climatic conditions; temperature and relative humidity on a Bioclimatic Chart, in order to determine the suitable passive and low energy strategies (Fig. 4). The analysis is a prerequisite and can be carried out manually, or by using computer programs like PASYS [7]. However, one may achieve points only according to the number of passive systems for heating, cooling and natural ventilation that were applied in the building (up to 4 passive systems), on condition that each system serves at least 15 % of the building floor area. A passive system, which serves more than one strategy, gets points according to the number of strategies that it complies with. The passive systems to be applied in the project, and the building area served by each system, should be documented and presented.

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Fig. 4 presents analysis of the weather condition: temperature and relative humidity, on a Bioclimatic Chart performed by PASYS. The analysis shows that only 16% of the time there is no need for AC for heating and cooling. 19% of the time passive solar heating is required, while comfort ventilation and thermal mass with night ventilation can eliminate the

need for mechanical cooling in summer by 16% and 24% of the time. On top of it, 48% of the time shading is required. By applying all these design strategies a 75% passive building was achieved. Because of the high humidity, the building can’t be 100% Passive.

                                     

.

Figure 4: Sussman Energy and Environment Building Laboratory in the Weizman Institute of Science, Rehovot. Analysis of the weather condition: temperature and relative humidity, on the Bioclimatic Chart (top left) and two of the Passive Systems applies: Sunspace for preheating the intake air during winter, and external sunshades required for summer

   

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

This Israeli Standard offers prescription/description methods and in addition a performance method to evaluate the building energy consumption. The energy performance method defines a reference building that complies with the mandatory Israeli Standard 1045 [10] that prescribes the required insulation and shading of the building envelope. Saving 20% of the energy consumption of the reference building is a prerequisite in all climatic zones, except in zone D (the Jordan Valley) that has a very hot climate. There are 5 grades. The percent required for achieving of A+ to D rating is different for residential and commercial buildings. Moreover, these numbers are not the same in the four climatic zones of Israel as it was impossible to achieve 50% energy savings in the climatic zone D. The hotter the climate is the less saving could be achieved. However, in all climatic zones, energy rating of A+ provides the green building with 16 points, while energy rating of C gives 4 points only (see table 3).

5.2. Environmental assessment in regards to the sun and wind (1-8 points) The building density in Israel is one of the highest in the world. The green code, as its name declares “Buildings with Reduced Environmental Impact” should ensure suitable environmental conditions to the surrounding buildings and open spaces, as well as the building itself in regards to the sun and winds. Analyzing the shadow cast by the surrounding buildings and objects and the shadow cast by the designed building, is a prerequisite. Points are awarded (1–4 points) according to achieved predefined amount of solar exposure of: a. the solar systems (PV and water heating solar collectors), b. the building elevation, mainly in the southern section, and c. the open spaces of the proposed designed building. Moreover, the building should comply with the requirements of keeping the solar rights of the neighbouring buildings and open spaces [8]. The last requirement is mandatory for high rise buildings (see Fig. 5). Zone A

Table 3: Energy Rating of buildings in IS 5282 and 5281 Energy Rating of Building IS 5282 Platinum A+ Gold A Silver B Bronze C Satisfactory D Failure F

Zone B

Green Building Points IS 5281 16 12 8 4 0 -

  Zone C

Zone D

  Figure 5: Solar Rights Requirements – The Descriptive approach

The environmental assessment includes also the analysis of the wind regime on pedestrian level in open spaces during the four seasons of the year. Evaluation of the desirable wind directions for ventilation and the undesirable winds directions that should be avoided should be performed according to the psychometric chart. The analysis is a prerequisite. Points may be awarded only according to the number of physical solutions applied for achieving natural ventilation in open areas, on one hand and protecting them from undesired winds on the other one (1-2 points). Using CFD or wind tunnel to evaluate the required level of wind velocity for the proposed activity in the open spaces, like sitting, strolling, walking, etc. [9] will provide two more points. The last requirement is mandatory for high rise buildings.

6. MINIMIZING ENERGY CONSUMPTION OF THE BUILDING Achieving points for minimizing the energy consumption of the building that is required for heating, cooling and lighting, is based on the Israeli Standard SI 5282 “Energy Rating of Buildings” [4].

The Israeli standard IS 5282 “energy rating of buildings” emphasizes the building architecture: envelope insulation and shading, windows size and orientation, building thermal mass and night ventilation for passive cooling, as well as the building geometry, compactness and proportions. The last point is very important for office buildings, as the depth of the building influences the daylighting (the most influential design parameter) that can be achieved in working areas. Hence, the energy required for electrical lighting can be reduced significantly. Also, in order to achieve better daylighting without glare, emphasis was put in commercial buildings on external sunshades and light shelves [11]. This is in contrast to ASHRAE 90.1 [12], the scope of which is: “This standard provides: minimum energy-efficient requirements for the design and construction of: 1. new buildings and their systems, 2. new portions of buildings and their systems, and 3. new systems and equipment in existing buildings. To ensure that the building is mechanically heated in winter or cooled in summer, the requirement is: “The provisions of this standard do not apply to: … buildings that do not use either electricity or fossil fuel”. Moreover, there is a minimum requirement of the capacity of the HVAC systems: “provided that the enclosed spaces are: 1. heated by a heating system whose output capacity is greater than or equal to 3.4 Btu/h·ft2 or 2. cooled by a cooling system whose sensible output capacity is greater than or equal to 5 Btu/h·ft2. This means that the emphasis in ASHRAE 90.1 is put on improving the mechanical system, and not on the design of the building itself.

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To cope with the scope of ASHRAE 90.1, the reference building is defined in appendix G according to the geometry of the proposed building, an action that practically eliminates the influence of the building’s geometry. Contrary to this, the reference building in IS 5282 is defined with fixed geometry and depth to allow daylighting. In such a way the geometry of the proposed building is considered and is influential.

7. SUMMARY & CONCLUSIONS Present situation of existing “green buildings” examples shows that a building may be labelled as “Green” with barely any improvement in its energy performance. Moreover, even when energy efficiency is considered, it may be achieved merely by improving the mechanical, electrical and hot water systems. There is no need to improve the architectural design from bio-climatic and passive solar aspects. Based on these conclusions, the author of this paper, who was in charge of the revision of the Energy Chapter of the Israeli “Green Building” Standard, and participated in the development of the “Energy Rating of Buildings” standard, has suggested few solutions: a. In the Energy Chapter of the Israeli “Green Building” Standard a minimum required points from the energy chapter should be requested in order to achieve each “Green Grad” level. b. Special bio-climatic and low energy architecture requirements should be imposed in order to achieve points in the energy chapter. c. In order to avoid the present situation that the minimum required points for energy saving may be achieved with no need for good architectural design, it was suggested in the “Energy Rating of Buildings” standard, to treat “Passive and Low Energy Building Design” separately from the hot water systems (that is mandatory in Israel) and the mechanical systems (AC and others, like elevator). This separation is also important because the building is designed to outlive the mechanical systems by a large margin.

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8. REFERENCES [1] E. Shaviv, Proc. 25th PLEA 2008 Passive and Low Energy Architecture Conference, Dublin – Ireland (2008) [2] LEED2009 for New Construction and Major Renovations.http://www.usgbc.org/ShowFile.as px?DocumentID=5546 (2009) [3] Israeli Standard IS 5281, Buildings with reduced environmental impact (“Green Building”) Under Revision (2010) [4] Israeli Standard IS 5282, Energy Rating of Building, Under Revision (2010) [5] BREEAM Offices, http://www.breeam.org/page.jsp?id=17 [6] J. Stamp, Greener Than Thou: Fed Building Too Green For LEED, http://sf.curbed.com/archives/2008/02/12/green er_than_thou_fed_building_too_green_for_leed .php (2008) [7] A. Yezioro and E. Shaviv, A Knowledge Based CAD System for Determining Thermal Comfort Design Strategies. Renewable Energy 8: Pergamom Press Ltd., GB. (1996) 133. [8] G. Capeluto, A. Yezioro, T. Bleiberg, E. Shaviv, “Solar Rights in the Design of Urban Spaces”. PLEA 2006 – Proc. 23th PLEA 2006 Passive and Low Energy Architecture Conference, Geneva - Switzerland (2006). [9] Building Research Establishment, Wind around Tall Buildings. BRE Digest, Concise reviews of building technology. Digest 390. (1994). [10] Israeli Standard IS 1045, Thermal Insulation of Buildings: Residential Buildings, Under Revision (2010). [11] E. Shaviv, A. Yezioro, I. G. Capeluto, Energy Code for Office Buildings in Israel. Renewable Energy, 33/1. Elsevier Science Ltd., GB. (2008) 99 [12] ASHRAE Standard 90.1-2007. (2007). Energy Standard for Buildings Except Low-Rise Residential Buildings. ISSN 1041-2336.

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Urban sustainability assessment systems How appropriate are global sustainability assessment systems? Dimitra KYRKOU1, Melissa TAYLOR2, Sofie PELSMAKERS3, Roland KARTHAUS4, 1

AVA, Sustainable Urban Design Research Group, University Of East London, London, UK 2 Hilson Moran & PassivHaus Trust, London, UK 3 AVA, MA Architecture: Sustainability & Design, University Of East London, London, UK 4 AVA, Sustainable Urban Design Research Group, University Of East London, London, UK ABSTRACT: This paper presents the findings of research on urban sustainability assessment systems for neighbourhood-scale developments worldwide. The main objective is to investigate how appropriate international urban sustainability systems are, and how these systems could be adapted to different local communities. This research paper aims to link the local approaches with the current global objectives of urban sustainability. The findings are based firstly on the application of LEED for Neighbourhood Developments and BREEAM Communities on several schemes officially assessed by the US Green Building Council and BREEAM, and secondly on a testing-application of both of the systems on the same pilot scheme. The research also involves a survey with questionnaires and contacts with designated assessors of LEED-ND and BREEAM Communities on how these systems perform in different localities, and an investigation on the qualitative aspects of those systems. As a conclusion, this paper suggests that before using a universal sustainability assessment system, it is necessary to analyze the local situation and identify the adaptability of using such a tool in a specific country and region. It highlights that a tailored version of globally accepted national urban sustainability assessment systems would work more effectively than a totally integrated global system. Keywords: urban sustainability, assessment systems, tools, BREEAM Communities, LEED ND

1. INTRODUCTION ‘Green Buildings’ have attracted international attention as a means to reduce CO2 emissions, as a response to global warming, the current energy crisis and the deterioration of the world’s natural environment. It is certainly true that a growing number of different assessment tools and frameworks have been developed during the last years “in order to support conscious environmental decision making” [1]. However, those numerous assessment systems are limited to the scale of environmental building design. “While the framework of assessment methods is clearly broadening, most assessment tools still focus on individual buildings. However, the sequence in the development of assessment methods is important in revealing the increasing acknowledgement of a broader context” [2]. According to Edward Ng, this broader context involves the urban scale. It is worth understanding that the way to sustainability passes through our urban environments. Buildings are only one part of the human lives and it is the cities as a whole that represent the modern urban style of living. Therefore, it is very important to understand that a sustainable way of living should effortlessly derive from the design of sustainable neighbourhoods, as green neighbourhood developments are beneficial to the community and the individual as well as to their environment. After realizing the significance of the sustainable urban living, several existing assessment systems

have recently introduced versions that address that broader context of urban scale. Such systems are: the US LEED for Neighbourhood Developments (LEED-ND) [3] and the Sustainable Sites Initiative (SSI) [4], the UK BREEAM Communities [5] and the SuBET [6], which was officially launched by the Steering Group for Sustainable Masterplanning in UK by Hilson Moran, as well as the Japanese CASBEE – Urban Development (CASBEE-UD) [7]. This paper will present the findings of in-depth research on those sustainability assessment systems on neighbourhood scale developments worldwide. In general, this paper aims to contribute to the prevailing debate of environmental assessment systems and to further enhance the currently limited research on urban sustainability assessment systems. Trying to link the local approaches with the current global objectives of urban sustainability, it will demonstrate that local versions of globally acceptable national urban sustainability assessment systems would work more efficiently than a totally integrated global assessment system.

2. METHODOLOGY Although there is a satisfactory amount of information on research concerning environmental assessment systems for buildings, the information provided for urban-scale assessments is still limited. As such there were several challenges in conducting an in depth analysis on the field of urban sustainability assessment. Therefore, apart from the review on existing literature and scientific articles, a more quantitative

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method was used during the research on urban sustainability assessment systems. As the main purpose of the research was to investigate how appropriate an international sustainability assessment system is; two urban sustainability assessment systems were reviewed and compared in order to test how ‘local’ or how ‘global’ their criteria are and how useful this is. For the purpose of this research, the ‘LEEDNeighbourhood Developments’ and ‘BREEAM Communities’ were used as the main methods for analysing an international sustainability assessment system of urban scale developments. These two rating systems were chosen as they are the most accepted and prevailing ones in the industry, with the highest amount of applications worldwide. Interestingly, they were originally conceived as national rating systems only. (LEED-ND for the US and BREEAM Communities for the UK.) The research involved the application of the above urban sustainability assessment systems in two different ways. Firstly, case studies of different urban developments were used, which had already been rated against LEED-ND or BREEAM Communities in relation to the locality of the places. The category of the locality was used as the criterion to review the different assessment systems as it is highly related with the local or the global character of a place. In addition, both systems were applied on the same pilot scheme, which was used only for the purposes of this research as primary data. This allowed an exploration of how the importance of the same site-location scored against both of the systems, and highlighted different approaches in the different rating systems. Furthermore, questionnaires were asked to be completed by the BREEAM Communities and LEEDND assessors worldwide, investigating their personal opinion on the feasibility of a global urban sustainability assessment system, through their experience on the application of BREEAM Communities and LEED-ND correspondingly. Finally, the comparative analysis between ‘LEEDNeighbourhood Development’ and ‘BREEAM Communities’ also involved a ‘quantitative and qualitative test’ of their credits, in order to investigate which aspects of urban sustainability can be measured and how this is related with the location of a place.

3. RESULTS 3.1. Rating of the same scheme against both LEED-ND and BREEAM Communities A future residential development project at southern Cambridge, Clay Farm by Place Partners, was used as the pilot scheme to be reviewed against both LEED-ND and BREEAM Communities. The testing assessment of Clay Farm against BREEAM Communities and LEED-ND showed that the Clay Farm masterplan could target 50% of the total available credits for BREEAM Communities, while it could score “76 points out of 100”, which is equivalent to a ‘GOLD’ level of certification according

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to LEED-ND certification levels. Both of the scores seem to be rather high for a project that did not initially intend to be certified under any urban sustainability assessment system. This highlights that when a project follows general sustainable urban design principles, it can achieve a high scoring against any local or non-local rating assessment system. The higher score against LEED-ND, being a US tool, compared to that against the UK’s BREEAM Communities, could be implicit by the fact that Building regulations and sustainability standards vary from country to country. For example, building code standards in the U.S. are lower than those found in the UK [8], hence a project in the UK would likely score higher under a less demanding US rating tool. The reliance on local building standards as a minimum starting point for the systems means that the ratings they subsequently award are affected. What is more, as far as LEED-ND scoring is concerned, it tends to be more heavily weighted towards rewarding new urbanism principles, which is generally accepted in mainstream urban planning in the US, rather than low environmental impact development. For instance, in the Clay Farm assessment, high scoring was gained mainly due to the provision of good public transport linkage and the effort for reduced car dependence; its location adjacent to already developed areas and to diverse uses that can offer a high number of job places and its ‘pocket principles’ that enhance the walkability of the neighbourhood and activate the frontages of the buildings along sidewalks. These principles are more ingrained in the UK’s planning systems and urban design principles of ‘compact city thinking’ and hence do not need to ingrain this into BREEAM. However, these aspects are mostly promoted with higher scoring within LEED-ND, as this is less prevalent in urban design; explaining the difference in bias between the two systems. Furthermore, LEED-ND gives some additional points for ‘regional weighting’, which, although it would offer an even higher score in the case of Clay Farm; in general it does not affect the final scoring significantly. As ‘regional credits’ is not considered a mandatory and significant criterion, thus it cannot be assumed that this criterion makes LEED-ND a ‘global’ system. In the case of BREEAM Communities, in a full assessment, it normally involves local and regional planning requirements assessed through a weighting system. As the rating of Clay Farm against BREEAM Communities was not conducted by a professional assessor and no data is available about the weighting by BREEAM, it has not been possible to go through this process, and so the framework and subsequent weighting according to regional priority, have not been applied in this assessment. Although this may not result in the most accurate scoring in this case, it shows that in general, BREEAM Communities allows for an adaptation of the system to different local and regional requirements, but not through a transparent process. An example of that is the recent ‘BREEAM Communities Scotland’ scheme which is not yet launched but is tailored to Scotland.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

This highlights the available bespoke service offering for international projects by BREEAM [9], where the assessment are adapted to take account of local issues rather than a top down approach. All in all, the above project proved that selecting a good development location is an important element of an urban sustainability assessment system. This perspective is embodied in prerequisites related to location which means that not all land within a given jurisdiction is eligible for certification. According to the Local Government Guide [10], by LEED-ND, it is suggested that “rather than issuing a ‘blanket’ mandate that all new development projects must achieve certification, it is more effective to use strategies outlined in the urban sustainability assessment systems to encourage development projects to pursue certification, remove barriers to achieving certification, or provide technical assistance to projects seeking certification”. Initial findings also highlight that ‘internationalising’ or ‘globalising’ standards can be rather biased to the region they originate from: after all, they appear to reflect the relative importance of ‘local issues’ into the weighting and scoring of their ‘global frameworks’. 3.2. Analysis of case studies officially assessed by BREEAM Communities and LEED-ND. The analysis of the previously officially assessed projects-case studies, involved the Athletes’ Olympic Village in London and MediaCityUK in Manchester for the BREEAM Communities as well as the scorecards of 59 participated pilot projects in the US in total, in the case of LEED-ND [11]. It has to be mentioned that it was difficult to find sufficient data about the assessments accomplished by BREEAM Communities, as it is not a transparent tool, offering no information to public related with the scoring of assessed projects. On the contrary, a lot of data is published and easily accessible through USGBC on LEED-ND assessed projects. The LEED–ND case study analysis indicated that the highest points were gained due to the preferred location of the sites, the opportunities provided for low automobile dependence and for great diversity and proximity to transit facilities. Green building performance or the protection of the ecology of the place, were secondary to site issues in the LEED-ND scoring. The above findings confirm that, in general, as far as the LEED-ND scoring is concerned, it tends to be more heavily weighted toward rewarding new urbanism principles rather than low environmental impact development. While these two principles are not mutually exclusive, there are significant differences in the ecological emphasis between the two, where BREEAM Communities tends to address environmental concerns more directly. Considering that LEED-ND is modelled under the principles of New Urbanism and BREEAM Communities are trying to comply with the strict UK regulations about sustainability, this confirms similar findings of the partial scoring of the Clay Farm pilot study. Indeed, the combination of the test application of LEED-ND and BREEAM Communities on Clay Farm, together with the analysis of the case studies already

assessed by these systems, verified that a rating system that is not developed for a specific region might be incompatible with local conditions. These rating systems may then fail to contribute to local sustainable development goals by prioritising global or ‘locally borrowed’ priorities, inappropriate to a different region. In summary, the appropriate sustainability assessment rating system ought to be adapted to address local contexts and conditions. In case of LEED-ND, the proposed revisions to its pilot version, undertaken as part of ongoing research at the University of East London, helped to address this issue to some extent. 3.3. Analysis of the Questionnaires The questionnaires that were completed by the BREEAM Communities and LEED-ND assessors for urban developments worldwide offered some interesting findings on the feasibility of a global urban sustainability assessment system, as well as on the credits that assessors thought should change when a system is to be adapted in different local situations. According to the findings, mainly the credits related with energy efficiency and the on-site renewables should be carried over from the global assessment tools to local situations. Similarly, credits related with flood risk, surface water-runoff, cycling networks and facilities as well as consultation and business issues were believed to be highly dependent on the locality of a place and should be adapted to reflect local requirements. The survey highlighted that “all the projects assessed against BREEAM Communities would have scored differently if located in a different country” [12] and that when a development addresses ALL of the aspects of sustainability, which is highly connected with the locality of every place, it can then achieve a high scoring against any urban sustainability rating system. 3.4. Analysis of the “qualitative & quantitative” aspects of LEED-ND and BREEAM Communities The comparative analysis between ‘LEED-ND’ and ‘BREEAM Communities’ involved a ‘quantitative and qualitative test’, in order to investigate which aspects of urban sustainability can be measured and how this is related with the location of a place. This investigation has shown that both of the systems mainly include quantitative issues and the aspects that are not taken into consideration in the sustainability assessment systems tend to be qualitative as they are difficult to measure. In particular, both LEED-ND and BREEAM Communities take into consideration the amount and the proximity to public spaces, the transit facilities and the decrease of car dependence. However, none of the systems seems to consider the quality of the streets, the quality of cycling networks or that of public spaces. This supports research findings that qualitative aspects are not being assessed by the urban sustainability assessment systems. In the same notion, despite the fact that both of the systems promote high density development and consider heights of the buildings, they do not include

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credits about the ‘street scape’ or the ‘townscape’, which are part of the city’s character. Although there are credits that count for the protection of historical buildings, there are no credits for the protection of the character within a neighbourhood, or its culture in general, all issues which are connected with the locality of a place. City character does not only derive from listed buildings alone: people, local activities, even the common materials or the colour of the buildings could give a neighbourhood its character that in turn, offers the neighbourhood a ‘community feeling’. These are clearly qualitative issues, and not objectively measurable, and of course, they are all considered as credits with high locality character. Another social issue that is missing from the urban sustainability assessment systems is community participation, in order to enhance ‘community feeling’ and thus makes the neighbourhood more sustainable. Although there are credits about the procurement of people, these only refer to the design or management stages, and they do not involve for example the promotion of common activities within the community. All the above issues that are not included in the sustainability assessment systems are ‘social’ issues, and thus qualitative and difficult to be measured. However, the holistic approach to the sustainable development derives from the common acceptance that “the ecological, economic and social aspects of sustainability are its main, significant and equal components” [13]. Therefore, if an urban sustainability assessment system aims to promote real sustainable places, it ought to include, apart from the environmental, social as well as economical issues. As a whole, according to David Rudlin and to Nicholas Falk, “Each element of the Sustainable Urban Neighbourhood represents an important principle; Sustainability refers to the ability of the neighbourhood and wider urban systems to be sustained over time and to minimize their environmental impact. Urban refers both to the location of the area and to its physical character whilst neighbourhood relates to the social and economic sustainability of the area, the community ties which hold it together and its relationship to surrounding areas. In this term, the urban sustainability assessment systems should include credits that will promote a neighbouhood that will be durable, will minimize its environmental impact, will consider the local character of the area and will create tight links between the people” [14]. This means that BREEAM Communities and LEED-ND should be updated to reflect this, if their aim is to create truly sustainable neighbourhoods.

4. DISCUSSION 4.1. Limitations in establishing a sustainability assessment system

global

The comparisons between the different applications of BREEAM Communities and LEED-ND and the ‘qualitative & quantitative test’ analysis of their credits, was not undertaken to find the ‘best

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performing’ urban sustainability rating system amongst the two; but to investigate whether there is a need for a new global urban sustainability system or whether national-level systems are the most appropriate in assessing different local situations. The initial research findings have shown that there are several limitations in the effort to establish a global sustainability assessment system. The analysis of the BREEAM Communities and LEED-ND applications demonstrated that these systems were never totally designed to be used across multiple countries and often have features with a significant ‘local’ flavour. As a result, none of the schemes would work perfectly if used in countries other than those within which the system was initially designed to work in. It is therefore suggested that, where used outside the native country, any of the systems should be tailored to take account of the local context. What is more, there are specific local characteristics which significantly vary across the world. The different size of countries, the variance of climate and natural resources together with the geological features and economic situation in different regions have made it difficult to develop a unified urban sustainability assessment system, let alone a country-wide one. Additionally, as any environmental assessment methodology needs to cover a wide range of issues, Thomas Saunders argues that “there is no other way that a system could remain up to date without significant initial investment and continual extensive maintenance” [15]. In many cases, or even whole countries, there is a general lack of environmental data, standardization and professionalism, that not only makes an update impossible, but an initial implementation of urban sustainability systems as to begin with. This is mostly true in developing countries, where although there is an increase in environmental awareness by the governments, and thus in ‘green legislation’, instead, there are few opportunities for infrastructure provision which is a key element in every rating system. It is therefore obvious that a global sustainability assessment system would not manage to balance the needs of sustainable development projects between developed and developing countries, and strengthens the argument for regionally tailored versions. 4.2. Increasing the adaptability of assessment tools to local conditions

the

In general, although a global urban sustainability assessment system would undoubtedly provide a systematic and useful approach for the urban sustainability assessment industry, many researchers have pointed out that urban sustainability assessment systems should be adjusted according to the background of a certain country or region. Cooper argues that such current international attempts at developing a universal, standardized method for assessing the urban sustainability are inherently ‘flawed’. He claims that such methods are found wanting in that they are culturally implicit, and that such methods or tools “treat the sustainability [of the] wider built

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

environment as simply a matter of energy and mass flows without due regard to the socio-economic and political dimensions of sustainability” [16]. Our research findings support similar thinking, even if the widening of systems to include the qualitative, would lead to more complex systems and ways of assessing the ‘unmeasurable’. However, the importance of this paper lies on the findings of the research that can show which criteria and aspects of the assessment systems are the most sensible to change according to local conditions. The economic viability of a number of sustainable interventions vary according to local market, incentives and planning / building regulations. While several assessment systems, like BREEAM Communities, provide a flexible mechanism suitable for global application, some countries will score more favourably due to the local market (e.g. feed in tariffs, consultation more readily carried out, local materials appropriate and available etc). This means that the credits related with those issues can more easily be adapted according to local market needs. Such credits include the ones awarding for example the use of reasonable resourced and recyclable materials or the ones related with community involvement, which can assure that local needs are taken into consideration. In addition, credits that promote energy efficiency and support the use of renewable resources can benefit from a ‘green’ local management, like a feed-in-tariffs system and thus, they should be carried over from the global assessment tools to local situations. Similarly, credits related with flood risk, surface water-runoff and biodiversity are believed to be highly dependent on the locality of a place and should be adapted to reflect local requirements, like the conservation of the native habitats. For example, water resource is now a real problem for the development in the north part of China, while it is a light issue in the south region, showing the need for setting priorities and in turn for setting a scoring system according to local needs. All these issues are highly linked to the local regulations and frameworks as well, increasing the need for adaptability of the assessment systems to local requirements. The example of reviewing a UKbased scheme against LEED-ND during our research proved that a ‘conversion’ system is needed to adapt all the requirements and the credits of the US system, according to the most equivalent frameworks and regulatory in UK. Only then the system could be used and reflected the needs of the UK market. Furthermore, the comparative qualitative and quantitative analysis between BREEAM Communities and LEED ND has demonstrated that a lot of qualitative social issues are usually missing from the assessment systems. This is due to the efforts of the establishment bodies behind those systems to make them more world-widely acceptable and easily used in an international base. However, at the same time this international character creates difficulties in addressing local issues related with culture, architectural character, human relationships and habits, and thus those aspects are totally absent

from the assessment systems. As a result, sustainability is not implemented successfully as not a holistic approach is undertaken, with a promotion only of the environmental aspect and not of the social or the economic. BREEAM Communities though includes a whole category dedicated to ‘Business and Economy’, although again the credits should be adapted to reflect requirements of the local market. A good approach towards the integration of local needs into an assessment system is ‘QSAS’ (Qatar Sustainability Assessment System), developed by two of the leading real estate companies in Qatar in order to implement sustainability principles in all of their future projects [17]. QSAS was the answer to the need of this sector for an assessment system based on the needs of Qatar and the region, since all other solutions were totally imported and did not go along with the society, culture, climate and various environmental conditions which exist in the region. What is important and should work as a best practice is that QSAS offers a lot of advantages which are not available in any other imported system. For instance, QSAS responds to urgent issues such as preserving the architectural identity of Qatar and the region, and enhancing the creative solutions to address other challenges like water scarcity and lack of nonhydrocarbon raw materials. Besides, this system determined the types of plants which are suitable to the Gulf environment, and are distinguished by low consumption of water as well as providing the suitable greening and other environmental issues. Therefore, this is an example of how an assessment system should be adapted to meet local requirements.

5. CONCLUSION In conclusion, this paper has shown that global urban sustainability assessment systems, as well as the adapted versions of already well established rating systems, have both advantages and disadvantages and it is therefore difficult to choose the most appropriate solution. Instead, it suggests that before using a universal sustainability assessment system, it is necessary to analyze the local situation and identify the adaptability of using such a tool in a specific country and region. This paper argues that a tailored version of globally accepted national urban sustainability assessment systems would work more effectively than a totally integrated global system. Therefore, all the credits, requirements and scoring of an assessment system should be adapted in order to meet local needs and to respond to priorities set by local planning, frameworks or even by the local character of the region. The criteria and aspects of the assessment systems which are the most sensible to change according to local conditions are mostly the ones related with energy efficiency and the use of renewable resources, but similarly, credits also related with flood risk, surface water-runoff and biodiversity. Furthermore, this paper suggests that the existing assessment systems should be further

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developed and adapted in order to include more qualitative aspects as well, like cultural issues related with the build environment, if they willing to promote and create truly sustainable environments not only at the places where they were originally designed for, but also world-widely corresponding to the different local needs. However, this paper is just the starting point for a discussion between the increasing number of scheme operators developing and running sustainability assessment methods for neighbourhood scale developments, suggesting that opportunities exist for new approaches to urban sustainability assessment systems. All in all, this paper suggests ways to increase the efficiency of the tools that we can use as environmental architects and urban designers driven by sustainability, by linking the local approaches with the current global objectives of urban sustainability.

6. ACKNOWLEDGEMENTS This research was supported by the ‘Sustainable Urban Design Systems research group’, of the school of AVA of the University of East London. The authors would also like to thank the BREEAM Communities assessors for completing the questionnaires and the USGBC for the valuable information provided.

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7. REFERENCES [1] A. Gasparatos, Embedded value systems in sustainability assessment tools and their implications, Journal of Environmental Management 91 (2010), 1613-1622 [2] E. Ng, Designing High-density Cities for Social and Environmental Sustainability, Earthscan, UK, USA (2010), 279 [3] Official website of US Green Building Council, www.usgbc.org [4] Official website of Sustainable Sites Initiative, www.sustainablesites.org [5] Official website of BREEAM Communities, www.breeam.org [6] Official website of HILSON MORAN, www.hilsonmoran.com/Services/Sustainability/ SuBET [7] Official website of CABSEE, Japan, www.ibec.or.jp/CASBEE [8] Official website of BREEAM, www.breeam.org [9] Official website of BREEAM Communities, www.breeam.org [10] LEED, Local Government Guide for LEED-ND, USGBC, October 2009 [11] Official website of US Green Building Council, www.usgbc.org [12] B. Warren, BREEAM Communities assessor of MediaCity at ‘Sinclair Knight Merz’, personal statement for the questionnaires, August 2010 [13] R. Cole and R. Lorch, Buildings, Culture and Environment, Blackwell publishing (2003) [14] D. Rudlin and N. Falk, Sustainable Urban Neighbourhood_ Building the 21st Century Home, Architectural Press (2009), 50 [15] T. Saunders, A discussion document comparing international Environmental assessment methods, BRE (2008), 8 [16] I. Cooper, Which focus for building assessment methods–environmental performance or sustainability?, Building Research & Information (1999), 27(4/5) [17] A. Horr, Dr, The Green Leaf, Qatari Diar Research Institute, (2009)

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Assessment of Sustainable Buildings A Case for Enabling Post Occupancy Verification Julie Gwilliam1 1

Welsh School of Architecture, Cardiff, Wales, UK

ABSTRACT: This paper illustrates, evaluates and tests the potential for the evolution of building environmental assessment methods (EAM) to both enable and require ongoing assessment of buildings, based on in-use performance. This is not to say that the existing evaluation of the EAM or sustainability of the construction is obsolete, rather that this does not go far enough to ensure the delivery of the step change required by current policy and global environmental drivers including climate change. Our argument for an EAM “+” would make mandatory all factors that allow post occupancy evaluation within “certified” sustainable buildings and go further to require use of such applications (including installation of, and collection of data from, sub metering for energy and water and ongoing evaluation of occupant comfort) to produce regular building MOTs. These would then inform ongoing certification of buildings. This process would further allow the acknowledgment of the changing nature of a certified “excellent” or “outstanding” building and require owners to continually improve their building’s performance to warrant the continued use of the title “excellent” or “outstanding” certification in marketing and corporate social responsibility statements, for example. Keywords: Assessment, Post Occupancy Evaluation

1. INTRODUCTION Learning from our mistakes is a philosophy we all rely on in life. However, in the context of Architecture, very little interest has historically been given to enabling a continued learning relationship with the performance of our buildings in practice. Indeed, despite a plethora of processes for assessing the performance of buildings in-use, commonly referred to as Post Occupancy Evaluation (POE), very few projects are ever subjected to such a post-mortem (Yudelson, 2009) [1]. It is argued here that the current approach to building procurement, where the design team walk away from their projects soon after practical completion, is not in the spirit of sustainable development. We are certainly not alone in this assertion. It is further stressed that assessment methods, such as BREEAM, widely perceived as the de facto measure of a building’s sustainability in the UK, do not in reality deliver buildings that realise carbon savings or the wider sustainable operational measures that current national and European policy requires from its built environment. The exception to this is the Display Energy Certificate, implemented in response to the EPBD and the only UK legislated measure that, for public buildings over 1000m2, reflects in use performance. This research explores the credibility gap (Bordass, 2003) [2] associated with current procedures employed through the critical evaluation of the BRE Environmental Assessment Method (BREEAM) for testing and certifying the environmental performance of buildings in the commercial sector. BREEAM represents a tried and tested tool for demonstrating and communicating the result of efforts and measures taken to reduce the

environmental impact of buildings (British Standards Institution and International Organization for standardization 2010) [3]. However, concerns have emerged that proclaim to question the credibility of the current assessment process, on the grounds that it fails to take into account absolute building performance (and therefore compliance).

Gas

Electricity

Figure 1: Actual vs. Predicted Performance (After Bordass 2003)

Buildings are presently assessed and certified according to information provided about how they are predicted to perform, rather than how they actually perform in use. Critical environmental performance data including energy usage and CO2 emissions, renewable energy yields and water consumption are all based on theoretical design calculations that are often never checked against real performance data. Furthermore, compliance with certain issues is based entirely on non-enforceable commitments made by various parties to perform specific tasks during the initial occupation and ‘running-in’ period. As such,

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true compliance with issues assessed in this manner will always remain questionable. This paper presents the case for inclusion of an additional “verification” stage as a mandatory phase of building environmental assessment. It should be noted that this additional phase of EAM is considered to be additional to the newly developed BREEAM InUse. The phase proposed by this work is termed a “Post Occupancy Verification”, ensuring the Sustainable functioning of a building during its initial occupancy phase; while BREEAM in use would be considered to follow and indeed focuses on ongoing improvement of performance of existing buildings rather than new build development.

Figure 2. Placement of Proposed Post-occupancy Verification stage

2. METHODOLOGY Firstly, a critical evaluation of the assessment criteria contained within each of the nine main BREEAM assessment categories (Management (10 factors/ Man), Health & Wellbeing (13/Hea), Energy (9/Ene), Transport (6/Tra), Water (4/Wat), Materials (7/Mat), Waste (4/Wast), Land Use & Ecology (6/Le), and Pollution(8/Pol)) was undertaken. This was intended to identify those constituent factors that require in situ or in use verification in order to validate design and or post construction phase assessment. For example, these are factors that despite appropriate installation, may or may not inuse be functioning appropriately, or indeed be in-use at all. Secondly, a Post Occupancy Verification methodology is proposed for each of the factors deemed to require in-situ / in-use verification. These methodologies can be seen to build upon widely applied existing Post Occupancy Evaluation investigation methods and techniques. They were selected in order to collect the necessary data required to perform the post-occupancy verification assessment, while balancing the ambition to develop a usable and repeatable methodology. Therefore methods that required prior knowledge, equipment or expertise were discounted, indeed where data collection was required, much of the process was designed to closely relate to the widely used Building Use Survey (BUS) [4] and the CIBSE TM22: Energy Assessment and Reporting Method [5], thus enabling a research output synergy with this existing dataset.

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Finally, the proposed “Post Occupancy Verification” methodology (POV) was tested through application to a case study BREEAM assessed building (VOSA Bristol HGVTS Offices, Avonmouth, Bristol, BREEAM Excellent, completed 2008) in order to evaluate credibility gaps in the existing BREEAM assessment process.

3. DEVELOPMENT OF THE POST OCCUPANCY VERFIRICATION TOOL 3.1. Assessment Factors for Verification The first stage in developing the POV methodology was to decide which aspects of the original BREEAM assessment should be addressed and why. Clearly, one of the major objectives of this exercise was to devise a simple methodology that is economically and logistically appropriate to administer, but nevertheless provided a valid tool for verification of in-use compliance. Initial critical evaluation of the list of BREEAM issues and their individual credit requirements identified unfeasible numbers of issues for evaluation. It should be noted that for this initial development phase this process has focussed on the assessment of new build owneroccupied buildings only. However, the process undertaken could be applied to any other of the BREEAM family of assessment methods and indeed other building assessment method such as LEED and Greenstar. This evaluation process aimed to ensure that the POV process was manageable and did not require excessive expenditure, in terms of both time and cost. Therefore, it was considered vital to limit its scope in a systematic manner. Firstly, those criteria that are defined as ‘Minimum Standards’ within the BREEAM Offices 2008 Assessor Manual, were identified as core to the process (BRE Global Ltd 2009a) [6]. Following an initial evaluation, some of these were deemed not to be relevant or fundamental to the on-going credibility of the assessment process and so were excluded from this POV method. In addition to these minimum standards, some additional BREEAM issues were identified as being fundamental to the credibility of an assessment and therefore worthy of inclusion. Others, although not strictly deemed as fundamental were included on account of the simplistic nature of assessment. The following set of criteria were used as a general guide for selecting which of the remaining BREEAM issues should be explored in detail and form part of the proposed post-occupancy verification stage: I. Issues that require a commitment to perform specific tasks during the initial occupancy period. For example, Seasonal Commissioning. II. Issues relating to internal environmental conditions and occupant comfort. III. Issues relating to the reduction of energy and water consumption. IV. Issues identified as vulnerable to initial postoccupancy adaptation and misuse. Table 1 below provides a summary of the issues included as part of the proposed POV methodology.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Hea3: Glare Control Hea5: Internal / External Lighting Levels Hea6: Lighting Zones/Controls Hea8: Indoor Air Quality Hea10: Thermal Comfort Hea11: Thermal Zoning Ene1: Reduction of CO2 Emissions. BREEAM “Min. Standard” Ene2: Sub-Metering BREEAM “Min. Standard” Ene3: Sub-Metering by Tenancy Ene5: LZC Technologies BREEAM “Min. Standard” Tra1: Public Transport Tra2: Proximity to Amenities Wat1: Water Consumption. BREEAM “Min. Standard” Wat2: Water Meter. BREEAM “Min. Standard” Le6: Long Term Impact

Review of energy performance inuse necessary to confirm predictions. Review of installed LZC technologies and their actual contribution. Review of transport options necessary to account for the “local development” credits. Review of local amenities necessary to account for “local development” credits. Review of consumption in-use necessary to compare estimated and metered levels. Considered as part of water use assessment. Review of long-term landscape and habitat management plan.

In addition to the credits listed in Table 1, 4 further credits were included as they were easily assessed in use by way of a walkthrough survey, namely: Ene 4: External Lighting; Tra 6: car parking capacity; Wst 3: Recyclable waste storage (BREEAM “min. standard) and Pol 7: Night time Light Pollution. It should be noted that issues exclusively connected with the building specification and construction were excluded from further assessment within the POV. Furthermore, compliance with issues that had already been fully substantiated by the PCR stage were also excluded from further assessment

Compliance adequately checked

BREEAM Credits

Man2: Considerate Constructors Man3: Construction Site Impacts Man8: Security Hea2: View Out Hea4: High Freq Lighting Hea7: Potential for Natural Vent Hea9: Volatile Organic Compounds (See HEA 8.) Hea12: Microbial Contamination Hea13: Acoustic Performance Ene8: Lifts Ene9: Escalator / Walkway Tra3: Cyclist Facilities Tra4: Pedestrian and Cyclist Safety Tra5: Travel Plan Wat3: Major Leak Detection Wat4: Sanitary Shut-off Le1: Reuse of Land Le2: Contaminated Land Le3: Ecological Value Le4: Mitigating Impact (See Le6) Le5: Enhancing Site Ecology Pol1: Refrigerant GWP Pol2: Preventing Refrigerant Leaks Pol4: Nox Emissions Pol5: Flood Risk Pol6: Minimising Watercourse Pollution Pol8: Noise Attenuation Mat1: Materials Selection Mat2: Hard Landscaping Mat3: Re-use of Façade Mat4: Re-use of Structure Mat5: Responsible Sourcing Mat6: Insulation Mat 7: Design for Robustness Wst 1: Construction site waste Wst 2: Recycled aggregates Wst 4: Floor finishes Man9: Publication of building information Man10: Development as a learning resource

At Practical Completion

Man4: Building User Guide. BREEAM “Min. Standard” Hea1: Daylighting

Justification Review of commissioning duties necessary to guarantee compliance. Review necessary to ensure the User Guide & contents made available to building occupants. Review of daylight levels necessary to confirm occupant comfort. Review of effectiveness of glare control necessary to confirm occupant comfort. Review of internal lighting levels necessary to confirm occupant comfort. Review of controls installed to confirm ease of use. Review necessary for confirm effectiveness of ventilation systems and occupant comfort. Review necessary to confirm occupant comfort. Review of controls installed to confirm ease of use. Review of energy performance inuse necessary to confirm predictions. Forms part of energy performance review.

During Construction

BREEAM Credits Man1: Commissioning BREEAM “Min. Standard”

Table 2: BREEAM credits not included in the proposed POV Methodology (Including justification for exclusion)

During Design

Table 1: BREEAM credits forming a part of the proposed POV Methodology (Including justification for inclusion)

X X X

X X

X X

X X

X X X X X X X X X X X X X X

X X X

X X

X X X

X

X

X X X X X X X X

X

X

X X X

Not assessed for offices (Education only)

3.2. Post Occupancy Verification Methodology Having established those BREEAM credits that require verification during the proposed POV, it was then necessary to establish an integrated methodology through which to undertake this assessment. The methods can be grouped under 5 broad categories: 1: Building User questionnaire, 2:

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Information requests, 3: Building Walkthrough, 4: Energy Audit and 5. desktop study. Desktop Study

Energy Assessment

3.3. Case Study Application of POV

Training Have you ever received instructions on the correct use of Heating controls? Have you ever received instructions on the correct use of Cooling controls? Have you ever received instructions on the correct use of Ventilation controls? Have you ever received instructions on the correct use of Lighting controls?

Please tick: Yes 1 2 No

Yes 1

2

No

Yes 1

2

No

Yes 1

2

No

  Figure 3. Example of Questions added to Standard “BUS” Questionnaire

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In order to evaluate the proposed methodology, it was applied to a case study building: VOSA Bristol HGVTS Offices, Avonmouth, Bristol, BREEAM Excellent, completed 2008, enabled by the cooperation of members of the design and the building’s estates team.

BREEAM Category

Management Health & Wellbeing Energy Transport Water Materials Waste Land Use & Ecology Pollution

9 13 18 15 6 9 3 10 15

9 7 13 10 5 4 2 10 10

No of Credits Relinquished at POV

Table 4: BREEAM credit Scoring PCR vs Post POV No. Credits Achieved at PCR

The building user questionnaire can be seen to focus on those credits that relate to the indoor environment as experienced by the occupants. This questionnaire uses a qualitative approach to the assessment of building performance. It is acknowledged here that building performance monitoring may play a useful role here. However, it was the intention of the authors to develop a method that was both practicable an appropriate, and as such the application of the occupants as the measurement devices to consider both winter (heating season) and summer (cooling season) performance was considered to be most economical in terms of time, equipment and cost. The questionnaire used was an adapted version of the Building Use Studies (BUS) (Building Use Studies Ltd, 2010) [4] standard form. Additional questions were added relating to training on and complexity of the controls for lighting and heating.

No of Credits Available

Building Walkthrough

Man 1 Man 4 Hea 1 Hea 3 Hea 5 Hea 6 Hea 8 Hea 10 Hea 11 Ene 1 Ene 2 Ene 3 Ene 4 Ene 5 Tra 1 Tra 2 Tra 6 Wat 1 Wat 2 Le 6 Pol 7 Wst 3

Information Requests

BREEAM Issue

Building User Questionnaire

Table 3: BREEAM Issues Against Proposed POV method

In order to obtain historical information about the building such as metered energy and water consumption data, it is the intention of this method that information requests should be made to those responsible for facilities management. This is intended to supplement information derived from documentation relating to the design intent. Meanwhile a building walkthrough, guided by a senior member of FM staff can be undertaken to fulfil the verification of a number of factors listed above, photographs being taken to provide evidence. The energy credits to be assessed through this proposed POV method are intended to enable the in use Evaluation and benchmarking of the energy performance of buildings. This is a complex process, and requires a tool that could enable the clear communication of an in-depth, robust energy assessment. It is the intention of the proposed method to make use of benchmarking to compare results with other ‘typical’ buildings of the same type, enabling re-evaluation of Ene-1: Reduction of CO2 Emissions. The CIBSE Energy Assessment and Reporting Method [5] was selected as the basis for performing this part of the assessment. Finally, in order to obtain the necessary information on public transport networks within the facility of a building or development a desktop study would be required, searching bus and train timetable information, assessing proximity of stations and stops.

-2 0 -5 -4 -1 0 0 -1 0

The detailed methodology for each of the 22 issues selected for post occupancy verification was applied and enabled evaluation of the achievement of credits as to whether the performance in use exceeded, equalled or failed to achieve the standard credited within the original BREEAM Assessment process. It was found that the credits awarded at PCR stage were significantly affected (Caller, 2010) [7].

 

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The results from the POV were systematically compared against the credits achieved at the PCR stage (summarised in table 4 above). It can be seen that the building lost BREEAM credits under the POV methodology in the Management, Energy, Transport Water and Land use & Eoclogy criteria. The reasons for these reduction in awarded credits are summarised as follows: • Man 1: No implementation of seasonal commissioning and so this credit was relinquished. • Ene 1: Energy performance of building was below the standard claimed at the PCR stage and 1 of the original 10 credits were relinquished. • Ene 2: Sub metering by energy usage, although installed, was not monitored and are not linked to the building management system, therefore long term collection and analysis of data was not enabled and the credit was relinquished. • Ene 3: Sub metering by floor (end user or department), although installed, was not monitored and are not linked to the building management system, therefore long term collection and analysis of data was not enabled and the credit was relinquished. • Ene 5: The yield from the installed LZC technology (Photovoltaic array) was significantly overestimated (41% estimated/ 13% actual). 2 of the 3 credits were relinquished. It was also unclear as to proportion of yield utilised in offsetting energy demand. • Tra 6: Additional car parking spaces were provided (40 rather than the 21 stated in design statement). 4 of the 8 credits were therefore relinquished. • Wat 1: Water usage exceeded stated target (Design - 1.45 m3 / person / year. Metered: 6.7 m3 / person / year). Estimated from site wide meter. All the credits were relinquished. • Wat 2: No building specific water meter was installed and the credit was relinquished. • Le 1: The site landscape and habitat management plan was not in the possession of the estate management staff – therefore it was assumed that it was not possible to follow the plan and 1 of the 2 credits were relinquished.

Management Health & Wellbeing Energy Transport Water Materials Waste Land Use & Ecology Pollution Weighted Score BREEAM Rating

15.0 8.1 9.8 7.6 4.2 3.3 1.7 15.0 10.0 74.7 Excellent

Weighted Score at POV

BREEAM Category

Weighted Score at PCR

Table 5: BREEAM Assessment PCR vs Post POV

11.7 8.1 6.1 3.0 0.8 3.3 1.7 13.5 10.0 58.2 Very Good

When compiled and weighted within the BREEAM process the impact of these alterations to the credits awarded after the POV process resulted in the downgrading of the building from its previous ‘Excellent’ to ‘Very Good’ status as illustrated in table 5. It must be noted here that difficulties were encountered in the process of undertaking the proposed POV methodology that can be categorised as relating to the availability and quality of data. The ability to verify the performance of the building was significantly affected by the reduction in active engagement with the performance of the building beyond the PCR assessment phase of BREEAM. For example, beyond this phase, the commitment to undertake seasonal commissioning was not upheld, the building user guide was not communicated successfully to staff and there was no system or process in place to enable the systematic collation, reporting and analysis of energy or water use, despite the presence of sub metering system, despite clear commitment to each of these issues during the initial design and assessment phases.

4. DISCUSSION This work has attempted to address the credibility gap associated with the current procedures for certifying environmentally sustainable building under building environmental assessment methods, focusing on the UK based BREEAM. This research has successfully developed and tested a methodology that aims to bridge this gap by verifying post–occupancy compliance and confirming in-use building performance. This work has shown that in relation to a number of factors there is potential for extending the assessment process to include a postoccupancy verification stage. Further, this work has demonstrated how existing post-occupancy evaluation techniques may be employed to gather the data needed to evaluate compliance. Results from the case study assessment presented have supported the case that buildings certified by BREEAM may not be performing as well as expected, or may be failing to comply with aspects of assessment procedures undertaken prior to occupation. It is therefore time to question whether the awarding of environmental certification based entirely on predicted performance assessment alone is appropriate, particularly in terms of energy consumption or carbon emissions where their actual reduction is key to the mitigation of the affects of climate change. In any event, this work reinforces the need for the BRE to respond swiftly to emerging questions of integrity, or else risk damaging BREEAM’s reputation as a legitimate rating tool. Development of future methods that begin to address absolute performance will be required to maintain the balance of rigor and practicality that is so fundamentally important to the success of BREEAM. It will require an interdisciplinary approach, drawing on existing tried and tested methods and tools where appropriate, but also creating and pioneering new ones. In summary the potential benefits of the adoption of the POV methodology here are considered to

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include its role in: acting as a filtration process, reserving the highest levels of certification for buildings that are proven to deliver in use sustainability; improving credibility, responding to current questions relating to integrity and rigor; encouraging project actors to revisit occupied buildings and learn from them and identifying common problems and failures, thus informing future BREEAM updates. Meanwhile potential barriers to future adoption of the proposed POV methodology include: increased fear of recrimination relating to claims on professional indemnity insurance; funding and planning consequences where buildings fail to achieve the required BREEAM rating in use; additional time and cost associated with carrying out the POV stage and delay in certainty over the assessment result until the POV stage is complete. As evidence of discrepancies between predicted and actual building performance become more widely publicised, either through more research or the introduction of mandatory DEC’s for all nondomestic buildings, it is suggested that EAM methods such as BREEAM should minimise impact on integrity through the introduction of certification that reflects in use performance.

systematic verification methodology proposed by this work may provide a framework by which such ongoing assessment beyond initial post-occupancy verification may be undertaken.

5. CONCLUSION

6. ACKNOWLEDGEMENTS

It is the assertion of the authors that further research is required in order to better understand the post-occupancy performance of BREEAM certified office buildings. A methodology has been developed with the potential to ensure that the spirit of BREEAM assessments is maintained during occupation. The proposed verification process has been shown to be robust, but could be further supported through alterations in the BREEAM methodology that would enable the implementation of post occupancy evaluations to be more straightforward. It is hoped that further case study investigations may be conducted involving a mixture of public and private sector projects across the UK, using the proposed methodology, that would enable common issues to be identified and help to target future research and development. Such studies would enable the collation of information about in-use energy performance and CO2 emissions, with direct comparisons made between figures for predicted and metered energy consumption. Although this research has attempted to address the credibility of BREEAM through the introduction of an additional assessment stage covering the initial occupancy period, it does not address the long-term aspects of environmental certification and the diminishing significance of an assessment result over time. Figure 5 illustrates the impact of improvement in standards on certification. It can therefore be seen that, given sufficient time, a building certified as ‘Excellent’ in, say, 2010 may only achieve a ‘Very Good’ rating if assessed again after a step change in environmental performance has occurred. This begins to lead us to the idea that environmental assessment should include regular ‘MOT’ style periodic assessment. A paradigm shift is needed to accommodate this approach and indeed the

Thanks the Estates Team at the Vehicle & Operator Services Agency (VOSA) as well as to Stride Treglown Ltd and BJP Consulting Group Ltd.

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Figure 4. Shelf Life of Building Environment Assessment.

7. REFERENCES [1] Yudelson, J. (2009). Green building trends: Europe. Washington DC: Island Press. [2] Bordass, W. (2003). System Boundaries: Joining up actual energy consumption and modelled estimates. Available at: http://www.usablebuildings.co.uk/ [Accessed: 3/7/2010]. [3] BSI & ISO, (2010). Sustainability in building construction: Framework for methods of assessment of the environmental performance of construction works. Part 1: Buildings. Switzerland: BSI. [4] Building Use Studies Ltd. 2010. BUS Methodology: Occupant Survey Graphics. Available at: http://homepage.mac.com/aleaman2/1113/index .html [Accessed: 20/8/2010]. [5] Field, J. W. and CIBSE. 2006. Energy assessment and reporting record : CIBSE TM22. 2nd ed. London: CIBSE, p. 26 [6] BRE Global Ltd. (2009). BRE Environmental & Sustainability Standard [Online]. Watford: BRE Global Ltd. Available at: http://www.breeam.org [Accessed: 15/6/2010]. [7] Caller, L (2010). Advancing the Credibility of Building Environmental Assessment through Post Occupancy Verification. MSc Dissertation submitted to Cardiff University.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

What is the Relationship between Design Excellence and Building Performance? With particular reference to education buildings YANTI CHEN1, DANIELA BESSER JELVES2, BRIAN FORD3 1,2,3

Department of Architecture and Built Environment, University of Nottingham, Nottingham, United Kingdom

ABSTRACT: This paper discusses the relationship between design quality and building performance. It describes an investigation of two recent award winning education buildings in the UK in terms of the attributes of „design quality‟, the actual energy performance and occupant perception of these buildings in use. Design quality, as evidenced by receipt of RIBA awards, may not necessarily imply good performance. The study is a pilot project to establish a methodology to assist the correlation of these attributes. Conclusions are drawn from the analysis based upon the completed buildings and post-occupancy evaluation. The assessment has involved onsite observation, and occupant feedback through questionnaire and surveys. It is hoped to extend this initial work to include a larger sample of award winning buildings to obtain a better understanding of the relationship between design excellence and building performance. Keywords: low carbon school, design excellence, energy performance, people perception

1. INTRODUCTION 1.1. Background It is now widely accepted that architectures should encompass the environmental task of reducing fossil fuel energy consumption in response to climate change and ‘peak oil’. Government and institutional pressures are influencing architects to design more ‘environmentally responsible buildings’. For many years, the Royal Institute of British Architects (RIBA) National and Regional Awards have promoted buildings of quality and rewarded architectural excellence. Over the last five years, there have been an increasing number of buildings that have received awards which explicitly attempt to address environmental design issues and reduce fossil fuel energy use. However, does award winning design achieve good building performance, and do award buildings offer a comfortable environment to their occupants? When we examine the relationship between ‘design excellence’ (established through peer review) and building performance, the priorities and pre-conceptions of the profession may be revealed. 1.2. Low carbon school programmes in UK Education buildings currently account for 13% of carbon emissions from non-domestic buildings in the UK. [1] For sustainability, the UK Government set up an extremely demanding goal that all new homes and new schools should be carbon neutral by 2016. The previous UK Government’s programme ‘Building Schools for the Future’ (BSF) was a £45 billion programme that focused on the key issues in the design process of new schools and the refurbishment of existing buildings. Implicit within the programme were the government’s targets to achieve

sustainability and low carbon emissions. [2] In parallel, the Commission of Architecture and the Built Environment (CABE) started a school design quality programme, which objective was to provide free advice and support for local authorities commissioning BSF schools, and conducted a professional panel supported by the Government to review the school buildings annually from 2007. [3] However, in July 2008, one of the CABE’s reports stated that nearly 80 percent of schemes reviewed by its schools design review panel were ‘mediocre’ or ‘not yet good enough’. [4] The review results pointed out the lack of awareness in the profession regarding the relationship between ‘design quality’ and building performance. Well-designed schools can impact on pupils’ behaviour and teaching activity positively and potentially raise the children’s awareness of sustainability. Therefore, education buildings have been set as research targets in this study.

2. RESEARCH METHODOLOGY This research assumed that education buildings in the UK that received RIBA awards have achieved a high level of design quality. On this basis, it is then reasonable to choose these award winning buildings to analyse their performance by site observation, energy efficiency and occupant responses to their environment. As the pilot study, two recent school buildings were chosen. One is an RIBA East Midlands (EM) Award winning building, and the other was praised for its environmental design. The objective was to explore whether the awarded building could achieve good environmental performance and whether the high performance project receives a good occupant response. Site observations and surveys were supplemented by theoretical analysis of daylighting performance using Radiance based simulations and post-occupancy evaluation.

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3. DEFINITIONS 3.1. Design Excellence A well-designed project is not only an architectural issue. It should achieve a balance between social, economic and environmental aspects, like the regular triangle showed below (Fig.1). It also, needs to avoid the situation like the light grey circle where a project with high environmental value has lost the connection with other aspects, such as social context or human interaction. [2]

Figure 1: Projects have varying balance between the triple bottom-line values of sustainability (Source: BRE, 2007)

RIBA EM Awards in association with Ibstock Brick Ltd and the East Midlands Development Agency have encouraged building excellence within East Midlands region. Most of the awarded buildings were praised because of their high architectural standards and contribution to the local environment. Architectural excellence as assessed in award schemes is determined by a process of peer review. Jury members may disagree on certain issues but results are presented as a concensus of views of panel members. On the other hand, design quality of low carbon education buildings should not only reflect traditional architectural values, but it calls for 60% reduction of carbon emissions compared with a school built to 2002 standards as well. [5] In order to achieve the challenging target stated by the UK Government, CABE supplied ten issues that should be included in a well-designed school. The ten issues included high design quality to inspire and engage users and the public, flexible design arrangement for different activities, a requirement for clear environmental strategies and convenient facilities and services, etc. [4]

a rational design needs to include an assessment not only illustrating the real performance but how this informs design assumptions and better solutions. [3] In this paper, the ‘building performance’ is based upon two aspects: energy performance and the response of occupants to their experience of the building in use. A. Energy performance According to the Zero Carbon Task Force, an 2 annual reduction of 12-14kgCO2/m (near 33% relative to probable total energy used by buildings constructed to the standards required by 2006 building regulations) could be achieved by measures with high energy efficiency, and the final target is 2 10kgCO2/m /yr. [4] In order to review the energy performance of individual buildings, different types of assessment systems have been offered by relevant Department, such as Energy Performance Certificates, Display Energy Certificates and BREEAM system, etc. Distinct ratings show the different levels of building energy performance. It is a directly visual way to understand how efficiently the building runs, but cannot fully represent its ‘environmental performance’. B. Occupant Perception Eventually, architecture responds to the natural environment and serves people, no matter how ‘sustainable’ it is expressed to be. Post Occupancy Evaluation is an essential approach to assessing building performance which is reflected through the feedback from users. The process of evaluating the actual energy performance and people’s perception of the quality of the interior environment were pioneered by Adrian Leaman in the PROBE studies. [4] It is assessing and comparing the actual response of building occupants towards internal environment performance. In this paper, the post-occupancy evaluation surveys were implemented at the Victor Miller building in Bowbridge Primary School, Newark, to understand if this energy efficient building could provide a comfortable environment to users.

4. CASE STUDY The cases chosen in this study are critically reviewed in terms of the design principles offered by CABE, CIBSE and DCSF in terms of ‘design quality’. Regarding building performance, the energy efficiency and some occupant feedback will be mentioned in the analysis. 4.1. Case 1: Sci-Tech, Oundle School

3.2. Building performance Compared with ‘design excellence’, building performance is less subjective and can be assessed by making site measurements and by post-occupancy studies. When it comes to low or zero carbon design,

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Figure 2: Sci-Tech, Oundle architecture.com, 2008)

School

(Source:

RIBA

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The Sci-Tech block at Oundle School, designed by Feilden Clegg Bradley Studios, received the RIBA EM Awards in 2008. It is designed for science, arts, design and technology. The concept of Sci-tech was shaped by ‘promoting learning through doing’. A. Design quality In an excellent integrated design, architects should consider how to make the building participate in local context, and how to maximise the advantages of nature to benefit the building as well. The site is facing south-east to north-west enabling the southern part of the building to benefit from solar gains in winter. (Fig. 3) The existing mature trees on the south side of the site, of historic Oundle, can potentially shade the building. New landscape to the north is introduced in the form of a new pool that controls water run-off and dependence on drainage system. The design of the landscape can be defined by three principles: maximising educational opportunities, maximising sustainability and minimising impact on existing features.

B. Building performance A comfortable indoor environment is an indication of good environmental performance. To analyse the building performance of Sci-Tech, three aspects: daylighting, ventilation and thermal comfort, have been discussed in this paper. Daylighting: To evaluate the daylight performance of the building, two chief types of space have been selected for simulation: laboratory space in the north (A), and the atrium gallery (B). (Refer to Fig. 3) Performance simulation was undertaken using – Radiance software. In order to create a well daylit indoor environment, the angle shaped north elevation of the laboratory space with large windows and skylights on the roof were designed to maximise the natural light. With the purpose to increase the light quality, the design of a glazed screen to the rear of the laboratories planned to allow top light into the back of the labs and to provide long distant views out through the laboratories to the landscape beyond. Additionally, low energy artificial lighting is used throughout the building.

Figure 5: The daylight factor distribution of different space in Sci-Tech shown on section. The dark areas in graphs described the average daylight factor (DF) was 5% that is the minimum standard for well daylit space. (Created by Chen referencing the testing results by Radiance, 2010) Figure 3: The site plan of Sci-tech, Oundle. A- laboratory space, B and D- Circulation, gallery and exhibition, Clecture room. (Created by Chen, 2010)

How to arrange the layout of the building based upon its function and user activity is another key issue in ‘design quality’. The layout has been organised so that the original concept of open views and connection to the landscape through the laboratories has been maintained. (Fig. 4) This design fully embodied the requirement of ‘flexibility’ in low-carbon school design and increased the pleasure to occupants connecting the indoor environment to the external environment.

Figure 4: The Sci-Tech gallery- Windows into worlds. It showed the concept of the design that it desires to open the building to the world by windows, involving activities, functions and the nature (After Feilden Clegg Bradley Studios, revised by Chen, 2010)

The testing results showed that the average daylight factor in lab areas (A in Fig. 5) was around 7.6% (ground floor) and 10.1% (first floor), respectively, which implied they were well day-lit. Even though the depth of the lab space was large, the rooflights on top of the two-storey high corridor could help increase the level of natural light. The daylight factor was adequate for doing experiments in the lab, and the uniformity ratio was above 0.5 which means the distribution of the interior light was even. When it comes to the exhibition space with glazed roof (B in Fig. 5), the average daylight factor was nearly 20% that was able to provide good natural light for exhibition. Ventilation: The laboratory space requires a high air change rate. The building is designed to use natural ventilation in most working areas, controlled by automatic window actuators, and the ‘existing underground labyrinth is used to precondition air for the auditorium's mixed-mode ventilation’ and use the air quality sensors for minimum fresh air. [5] Moreover, designers supplied openable extracts on top of the roof and walls to exhaust warm air heated by internal gains. (Refer to Fig. 6)

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Figure 6: The ventilation of the laboratory space and the corridor (Source: Max Fordham, 2009)

Thermal comfort: The structure of the building is all reinforced concrete, so walls and soffits provide significant thermal mass, which responds slowly to fluctuations in temperature and aids passive thermal control in both summer and winter. In addition, the green roof of Sedum plants either reduces the rainwater running off, or enhances the balance of the micro-ecosystem, and could be viewed as a good landscape in the school. [6] Reduction of carbon emissions: A passive energy system was exploited in this building, integrated with renewable energy system involving roof-mounted, flat-plate, solar-thermal collectors generate hot water services for the laboratories, and polycrystalline photo-voltaic panels supplement the electrical capacity. The building achieved approximately an energy reduction of 40 to 60% as compared to conventionally controlled schools. Only the reduction of CO2 emissions from the controlled lighting system is from 8 million to 2.8 million tons per year. In terms of ventilation, it also saved 78% of energy consumption compared to a conventional mechanical ventilation system. Regarding the thermal comfort, the radiant floor heating system is controlled in 16 zones and saves 50% of the energy as compared to a conventional heating system.

community’s performance in a green way thus it was the winner of the BSCE 'Greening the School Community' Industry Award 2009. [7] A. Design quality The site of the school is surrounded by a residential area, facing south to north. (Fig. 8) The design of the main facades of the building have been sheltered by other school buildings, additionally, the southern facade is fully exposed to a lawn with direct prevailing wind from southwest. The natural context is favourable for the building with nice view and activity area, as well as providing fresh air that might conduce to natural ventilation, especially for night time cooling. Furthermore, the initial designed orientation could supply a good opportunity for maximising natural light for indoor environment; however, the overheating might become a problem by the direct sunlight in summer.

Figure 8: The site plan of Victoria Miller Building (Source: Offered by Daniela Besser Jelves, revised by Chen, 2010)

4.2. Case 2: Bowbridge Primary school

Figure 9: The layout of the ground floor and the first floor of Victoria Miller Building (Source: Offered by Daniela Besser Jelves, revised by Chen, 2010)

Figure 7: Victoria Miller Building, Bowbridge Primary School (Source: http://www.bowbridgeprimary.com, 2009)

The Victoria Miller Building is one of the newdesigned buildings in Bowbridge Primary School, located in Newark, Nottinghamshire, which aims to set up an eco-friendly school which is as low carbon as possible. In addition, the school was designed as a ‘learning building’ supposed to promote the whole

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In the building layout, it is clear that a large atrium space (the light areas in Fig. 9) has been designed as a crucial element on the south part of the building, and all the teaching areas were located in the north of the building (the dark areas in Fig. 9) Architects planned to make use of the big atrium playing as a buffer zone that targets to moderate direct sunlight and adjust the temperature of the adjacent areas, and provide flexibility to various activities as well. Regarding the layout of the building, the atrium took approximately 50% of the floor area.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

While the initial concept has advantages, such a large volume might bring some negative impacts to the interior environment, such as acoustic problems and possible overheating that should be avoied in school design. B. Building performance The building was designed with the purpose of being ‘low carbon’, so a series of environmental strategies have been involved within the building design. Daylighting: To analyse the daylight performance of Victoria Miller Building, two main areas were selected for simulation: classrooms and the atrium space. (Refer to Fig. 9) Performance simulation was undertaken using Radiance software. Architects proposed using the atrium to bring more natural light for benefiting surrounding classrooms. Nevertheless, the analysis result showed that except the atrium on the ground floor reached a good daylight factor (9.64%), the average daylight factor of other testing areas, particularly the northern classrooms on the ground floor, were around or below 5% that is the basic value to support normal activities. (Fig. 10) The section of the building displayed the uniformity of the daylight factor in different spaces. It illustrated that the value of the daylight factor and the uniformity of the classroom on the first floor was better than on the ground floor. It has not offered an excellent visual environment even for the chief function.

Figure 10: The daylight factor distribution of the Victoria Miller Building showed on section (Source: Offered by Daniela Besser Jelves, revised by Chen, 2010)

Ventilation: The building was designed being naturally ventilated with automated vents. The vents are the windows on main elevations as well as the rooflights. It has a computerised system controlled by relevant variables that are internal and external temperatures, wind speed, direction and precipitation. Furthermore, it could be in charge of the window opening when the interior content of carbon dioxide is extreme high. The component grilles in classrooms would allow the wind to pass through side windows to rooflights vents by air leaves, using stack effect. (Refer to Fig. 11)

Figure 11: Passive ventilation strategy of Victoria Miller Building (Source: Nottingham County Council, 2009)

Thermal comfort: The architects have considered about the overheat issue thus the atrium in south was designed to avoid overheat problem. Nevertheless, if the internal temperature was high enough the passive ventilation by stack effect will lose effect. With the purpose of keeping interior thermal comfort, particular in classrooms, radiators are supplied with thermostatic fittings. When the internal temperature was below the set one, radiators will be turned on. During the occupied period, the set temperature is 19 degree, in contrast to 12 degree targeting to saving electricity consumption and protecting the building fabric.

Figure 12: The energy rating of Bowbridge Primary School (Source: Display Energy Certificate, 2009)

Rating: Victoria Miller Building reached rating A in the Display Energy Certificate, which implies that the building performes well in terms of energy efficiency, compared with the typical school (rating D). (Fig. 12) According to its energy report, the energy 2 consumption of the building was 35 KWh/m /year in 2 heating and 21 KWh/m /year in electricity, respectively. Comparing with the energy usage in typical school, 50% of reduction in average has been reached. C. Occupant perception In order to find out whether this building with good energy efficiency could offer a comfortable indoor environment to its occupants, a post-occupancy evaluation has been implemented by means of surveys that were offered by Adrian Leaman in order

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to understand how occupants feel towards working in this building.

excellence and environmental thinking during design process, with attention to how the building works in real and occupant perceptions towards the building in use. This paper, as a pilot study, explored the balance between architectural design quality, environmental performance (sustainability) and occupant perception, and it was a start to rethink the essence of ‘environmental design’. Whilst the limitation of the research examples is hardly to draw further conclusions, it calls for a long-time effort in future.

6. ACKNOWLEDGEMENTS The authors would like to thank Daniela Besser Jelves of the Departmentl of Architecture and Built Environment, Nottingham University for her assistance in the light performance analysis and post occupancy evaluation, and Professor Brian Ford for his patiently revising. In addition, a special thanks to Feilden Clegg Bradley Studios for their supportive information regarding Oundle School.

7. REFERENCES Figure 13: The summary of the overall building performance in post-occupancy evaluation (Source: Usable Building Trust offered by Daniela Besser Jelves, 2010)

Figure 13 shows the summary of the feedback from occupants towards the building environmental performance, it illustrated that the overall result was better than the typical score, particular in architectural design, spatial pleasure to visitors and lighting. Nonetheless, we can see that the thermal comfort was not completely achieved, especially in summer (Refer to the first item of Fig. 13), and the people reflected the noise issue as well (Refer to the sixth item of Fig. 13). According to the user feedback and the building design analysis, the overheating and acoustic issues existed in the building, which indicated that the design of the atrium space might need improvement.

5. CONCLUSION Oundle School was a positive example, designed with careful consideration of spatial interest and sustainable thinking, at the same time, its building performance showed that it supplied interior comfort and reduced carbon emissions. While Bowbridge School aimed at being as carbon neutral as possible, however, the occupant response showed that the comfort was not completely achieved based on various environmental technologies. Even though the case study cannot represent all the award winning architectures, to a certain extent, it indicated that ‘design’ is not equal to ‘performance’. For example, a building endowed with ‘sustainable’ title may be conducive to good results in energy saving, such as A rating in certain certificates, but it probably ignores the essence of architecture that is to supply a comfortable environment for people, a sense of ‘well being’, as well as design quality. It may be concluded that an integrated design of architecture should combine a concern with architectural

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[1] BSF (online) http://www.teachernet.gov.uk th (Accessed 17 August 2010) [2] BRE, (2007). A bre guide: Design Quality Buildings, BR 487, London [3] CABE (2007). Leaflet of CABE‟s new schools design quality programme, CABE, London [4] CABE (2008). Most BSF designs “not good enough, CABE, London [5] DCSF, (2010) Final Report of the Zero Carbon Task Force (Online) www.teachernet.gov.uk/publications [6] Gluch, P., Raisanen, C., (2009). “Interactional perspective on environmental communication in construction projects”, Building Research & Information Journal, Vol 37, Issue 2, pp.164-175 [7] Preiser. W. FE, Vischer. J.C, (2005). Assessing Building Performance, Elsevier ButterworthHeinemann, Oxford [8] Leaman, A., Bordass, B., (2001). Assessing building performance in use 4: the Probe occupant surveys and their implications, Building Research & Information Journal, Vol 29, Issue 2, pp. 129 –143 [9] Energy Consultant of Oundle School is available on WWW at Maxfordham internet page: < http://www.mfp.co.uk> (Accessed 22 August 2010) [10] S&C Square Brochure, (2007). Oundle School, Available on: http://www.concretecentre.com/PDF/CQWinter20 07.pdf [11] Bowbridge Primary School (online): http://www.bowbridgeprimary.com (Accessed 22 August 2010)

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Sustainable architecture and sustainable design assessment tools Wim ZEILER Technische Universiteit Eindhoven, Eindhoven, Netherlands

ABSTRACT: There is a strong need for more efficient and more sustainable buildings. However sustainable architectural design management is a problem. Especially the focus is on Multi Criteria Decision making within the design process and how to support this, so that the decisions about fulfilling sustainable aspects in the design are made transparent for all stake holders within the design process. The four most popular sustainable assessment tools in the Netherlands, Greencalc+, Ecological Footprint, LEED and BREEAM, were then applied to the set of 8 state-of-the-art buildings and the results compared. The key question to be answered is do current environmental assessment methods provide a good measure of sustainability? Therefore the conclusions of our research will be used to draw some conclusions. Keywords: sustainable assessment tools, design support

1. INTRODUCTION Building design is changing, according to Holzer [1] there is a recent move from prescriptive project-briefs in favour of more performance-orientated design. The description of a building through its performative qualities is a key aspect in enabling a control over issues of project cost (clients) and sustainability (public domain). Clients have become especially sensitised to the value for money aspects of design to the point where project briefs are handed out with specific building performance-targets that need to be met [1]. The public domain and the authorities are mostly responsible for including building sustainability as key drivers in architectural design. Environmentally sustainable design became a requirement to reduce energy consumption and emissions [1]. As a result there is a strong need for more efficient and more sustainable buildings. At present it is difficult in the conceptual design phase to define the life cycle performance of buildings in an objective way to efficiency and sustainability. As the design proceeds, more information and detail will be developed [1]. Addressing reasons for the complexity of common design problems, Kalay [2] points out that projects undertaken in the building industry differ from those in other industries such as carmanufacture and aerospace due to the fact that each project is unique [1]. Architectural design often deals with the unknown where problems are defined and solved concurrently while designing and during construction. Holzner [1] states that collaboration between architects, engineers, construction managers and owners is difficult as each group has different world views and different modes of practice that are almost incompatible with each other [2]. One mode of practice [1], applied by specialists such as engineers, is dependent on precise problem and goal definitions before they can start to search for solutions, whereas architects – who apply a mode of practice through discovery - are often not capable of

“defining desired effects until the design process is well on the way.” [2] Conventionally, architects are somewhat tardy when inviting engineers to join their projects. However by only introducing consulting engineers to participate in the later stages of the design process, engineers are commonly assigned a merely fixing role. This provides little opportunity for creative engineering solutions at the conceptual design stage [3]. The main part of the project costs are allocated in the early conceptual phase of product development, still in this phase only few resources (manpower, money) are actually spent on the project [4]. By the dichotomy of this design process at the early stages of design there is little information, even though nearly all the important decisions have to be made at this time, as Fig. 1 [5] shows.

Figure 1. Relation between allocated and actually spent costs during a design project [4] and Influence / information contradiction at the early stages of design [5] Traditionally the costs of the building to be designed, takes a central place in thinking of the design team. However more and more the insight is growing that it is not the costs of the building to be designed that should be central but the needs of the humans for which the building is intended and the effects during the whole life cycle of the building.

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This leads to a new approach in which the human needs and especially the sustainability characteristics are the key aspects, see Fig.2 [6].

Figure 2: Degree of responsibilities of professionals with respect to environmental design in different stages [6] At present it is difficult in the conceptual design phase to define the sustainability of buildings in an objective way. Goal of this project is to examine and to understand differences between different sustainability assessment building rating systems. To select a good set of reference buildings which can be used to test the sustainable assessment tools different buildings were compared and finally a set of 8 buildings was determined.

2. METHODOLOGY Multi-criteria decision-making (MCDM) is a generic term for the use of methods that help people make decisions according to their preferences, in cases characterized by multiple conflicting criteria [17].MCDM methods deal with the process of making decisions in the presence of multiple objectives. In most of the cases, different groups of decisionmakers are involved in the process. Each group brings along different criteria and points of view, which must be resolved within a framework of understanding and mutual compromise [18]. MCDM techniques have two major purposes [19]; - to describe trade-offs among different objectives. - to help participants in the planning process define and articulate their values, apply them rationally and consistently, and document the results. The object is to inspire confidence in the soundness of the decision without being unnecessarily difficult. As a result it will be necessary to supply information about the sustainability of building service applications at a much earlier stage in the design process. And, since this stage is where most decision-making takes place, possible sustainable architectural concepts will then have a much better chance of actually being implemented. Often decision makers assume that sustainable design is mainly about resource conservation – energy, water, and material resources. The last ten years, however, has seen a dramatic broadening of the definition of sustainability to include assurances for mobility and access as affected by land use and transportation, for health and productivity as affected

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by indoor environmental quality, and for the protection of regional strengths [7]. This broader definition of sustainability is represented in the US by the LEED™ (Leadership in Energy and Environmental Design) standard of the US Green Building Council [7]. The Center for Building Performance and Diagnostics at Carnegie Mellon University likes to expand this definition even further, to give greater emphasis to contextual and regional design goals, to natural conditioning, and to flexible infrastructures that support change and deconstruction [7]. Sustainable design offers architecture of long term value through 'forgiving' and modifiable building systems, through life-cycle instead of least-cost investments, and through “timeless delight and craftsmanship” [8]. The use of sustainable energy will soon be the major guiding principle for building planning practice. This asks for new design approaches. Synergy between design and assessment methods is necessary to really get transparent and understandable tools for supporting decision making on sustainability issues in the conceptual phase of building design. Nowadays design is conducted more and more in multi disciplinary design teams with a view towards integrating all aspects of the life cycle aspects of a design. This makes design a complicated messy process [9]. Achieving environmental goals makes the task more difficult for designers as for most consumers, energy efficiency and recyclability are less important product attributes. This means that designers cannot compromise other product attributes in becoming green [9]. Often most of the choices in the design process may be made by intuition and according to simplified decision rules, which is necessary and inevitable [10]. This makes it almost impossible for the different design team members to understand the implicit argumentation of the decisions. Therefore there is a need for formalized discursive methods to structure the decision process and make the process transparent [11]. This would make it easier to share the information and argumentation on which decisions are made within the team. (Sustainable) Quality can only be determined by a multi-criteria, multi-disciplinary performance evaluation, which comprises a sum of several satisfaction/behaviour functions [12]. Therefore new decision support tools are necessary especially for the sustainability assessment of a design. At the moment there are quite a few sustainable assessment tools for the commissioning of buildings. Therefore we wanted to investigate their differences and usefulness. We decided to select the four most popular sustainability assessment tools within the Netherlands at this moment: Greencalc+, Ecological Footprint, LEED and BREEAM. 2.1. Sustainable assessment tools First we wanted to define a representative set of buildings to test the sustainability assessment tools with. Therefore in November 2003 a project was started, in which students compared 15 Dutch and

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

15 German modern office buildings. From that project the 6 best Dutch and German buildings were compared more thorough with each other and it was examined in which extent the Dutch and the German buildings are sustainable [13]. The first and second stage of the research was necessary to get a good understanding and experience with the evaluation of building performances. This led to a selection of high performance buildings which could become leading examples in sustainable building design. This is of course an excellent group for the comparison of ‘green’ building assessment tools such as BREEAM, LEED, Greencalc+ and Ecological footprint”. It is necessary when analyzing the tools to use the same objects and aspects as a basis for comparison. From our former studies we selected the 5 best buildings; Hoogheemraadschap in Leiden (The Netherlands), Thermo Staete in Bodegraven (The Netherlands), WWF in Zeist (The Netherlands),Spherion in Dusseldorf (Germany) and Energy forum in Berlin (Germany). To look for sensibilities we added three buildings which were developed using specific sustainable design strategies: XX building in Delft (calculated life expectation 20 years), the first Cradleto Cradle office in Amsterdam and the new head office of Rabobank Netherlands in Utrecht. 2.2. Ecological footprint The Ecological footprint analysis compares human demand on nature with the biosphere's ability to regenerate resources and to provide services. It does this by assessing the biologically productive land and marine area required to produce the resources a population consumes and absorb the corresponding waste, using prevailing technology. This approach can also be applied to an activity such as the manufacturing of a product or driving of a car. This resource accounting is similar to life cycle analysis where in the consumption of energy, biomass (food, fibre), building material, water and other resources are converted into a normalized measure of land area called 'global hectares' (gha). The Office Ecological Footprint Calculator is a questionnaire which allows you to estimate how much land it takes to run and maintain your office. The input values for this program are divided in the following six groups: Building and construction: Energy & water: Food: Travel: Consumable items; Recycling. 2.3. Greencalc+ The development of GreenCalc started in 1997. The Greencalc+ assessment method is a questionnaire which allows you to estimate how much land it takes to run and maintain your office. It that can be used to calculate what the developers call the environment index of a building. This is done by calculating the environmental impact of the buildings by Life Cycle Analysis (LCA). The GreenCalc+ software consists of four modules, each representing a different aspect of the building characteristics; mobility, materials, water and energy.

The input values for this program are divided in the following four groups: Materials: Energy: Water: Travel to and from work: 2.4. LEED LEED was developed by the US Green Building Council (USGBC) for the US Department of Energy. The pilot version (LEED 1.0) for new construction was first launched at the USGBC Membership Summit in August 1998 [14]. In March 2000, LEED Version 2.0 based on modifications made during the pilot period was released. The most current LEED for New Construction Version 2.2 was released in November 2005. Current versions for other building types, including schools, homes, etc. were either released in 2006 or scheduled to be released. LEED registered projects are in progress in 24 different countries, including Canada, Brazil, Mexico, India and China, and the World Green Building Council— an affiliation of seven national green building councils, including the US. The LEED reference Guide presents detailed information on how to achieve the credits which are divided in the following six groups [15]: Sustainable site: Water efficiency:,Energy & Atmosphere: Materials & resources: Indoor Environmental Quality: Innovation & Design process. 2.5. BREEAM The first Building Research Establishment Environmental Assessment Method (BREEAM), launched and operated by the Building Research Establishment (BRE) in UK, came into prominence in 1990 [14]. Version 1 BREEAM for offices was first revised in 1993. The second revision was launched in September 1998. The current BREEAM version for non-domestic premises is BREEAM 2008. It covers a range of building types, including offices; industrial premises eco-homes; courts; prisons; retail outlets; schools; multi-residential, etc. It is one of the bestknown schemes and has embraced 15–20% of the new office building market in the UK. BREEAM has also been taken as a reference model when similar schemes were developed in Canada, New Zealand, Norway, Singapore and Hong Kong. The input values for this program are divided in the following eight groups [15]: Management: Health & wellbeing: Transport: Water: Materials: Land Use: Ecology: Pollutions.

3. RESULTS 3.1. Comparing BREEAM, LEED, Greencalc+ and Ecological footprint. To select a good set of reference buildings which can be used to test the sustainable assessment tools different buildings were compared and finally a set of 8 buildings was determined. The four most popular sustainable assessment tools in the Netherlands, Greencalc+, Ecological Footprint, LEED and

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BREEAM, were then applied to the set of 8 state-ofthe-art buildings and the results compared, see Fig 3 to 6. Many subjects are checked with the checklists of LEED and BREEAM. But not all subjects can be used for comparing all programs because of Ecological footprint and Greencalc+. Ecological footprint and Greencalc+ can only be compared at the aspects “materials, land use & ecology”, “energy”, “water” and “transport”. All assessment methods are expressed in different values, namely: Global hectares for the program “ecological footprint”, Earths environment costs (€) for Greencalc+, Credits for the checklists of LEED and BREAAM. To compare all assessment methods, they need to be calculated in percentages per subject for each building (%). All assessment results of the subjects for the different tools are expressed in percentages so that they can be compared with one another. The total results of the 4 common aspects (energy, transport, water and materials, land use and ecology) of the assessments methods show that there is a rather big fluctuation in total score between buildings, see Fig. 7,8,9,10 and 11.

Figure 3: Hoogheemraadschap Leiden & Thermo Staete, Bodegraven

Figure 4: WWF, Zeist

Figure 7: Score different environmental assessment tools for energy

Figure 8: Score different environmental assessment tools for transportation

& XX-building, Delft

Figure 9: Score different environmental assessment tools for water

Figure 5: Cradle2Cradle Rabobank, Utrecht

office,

Amsterdam &

Figure 6: Spherion, Dusseldorf & Energy Forum, Berlin

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Figure 10: Score different environmental assessment tools for water materials

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Figure 11. Results of all four aspects of the different assessment tools This makes it very difficult to use them as a management tool within the sustainable architectural design. The following Tabel 1. shows the order of ranking from the best to the worst results, resulting from each different assessment method. Tabel 1. Ranking as a result from the evaluations by the different sustainable assessment tools.

4. DISCUSSION We think that the proposed sustainability assessment tools could be a support for Multi Criteria Decision Making in the conceptual design phase. The sustainable quality can only be determined by a multi-criteria, multi-disciplinary performance evaluation, which comprises a sum of several satisfaction/behavior functions [16]. The more effective way of achieving sustainability in a project is to incorporate environmental issues at a stage even before a design is conceptualized. It is important to separate project design and project assessment as building design takes place at an early stage and the assessment process is usually carried out when the design of the project is almost finalized [20,21] Therefore, the traditional use of environmental assessment methods as design guidelines cannot be sufficient. Consequently, in order for environmental building assessment methods to be useful as a design tool, they must be introduced as early as possible to allow for early collaboration between the design and assessment teams. They also need to be reconfigured so that they do not rely on detailed design information before that has been generated by the designer [12].

5. CONCLUSION Applying the different sustainable assessment tools leads to different choice for the best building, which means that applying such tools for decision within the conceptual design phase would also lead to different outcomes. The choice of the decision supporting tool is thus of great importance for the results of the decisions. So before applying a sustainability assessment tool the sensitivity of the tool to specific aspects of the design program should be evaluated. Probably this can be best tested by applying the different sustainability assessment tools to a set of reference buildings related to the design task at hand. Those reference projects should be selected based on the sustainable architectural style which is preferred by the client as well as the sustainability goals. Based on these criteria a fitting sustainable design assessment tool can be selected. In this way the outcome of the tool can be supportive in de decision process. The different sustainability assessment tools all have still some flaws. The organizations behind the assessment tools are of course not ignoring the critiques and as a result the green building standards are ‘still’ under construction [23]. At the moment the current sustainable assessment tools are still not really adequate for supporting the early phase of architectural design. Often they are used as a checklist afterwards instead of being used early in the design process. Sustainability is a diffuse blurry term that mixed economic, social and environmental aspects [24]. However sustainable architecture practices should be orented by clear targets that express the society’s vision of a sustainable future. The evaluation should be performance based in order to link specific sustainable goals and quantify the success of the outcomes {24]. Buildingaspects should be based to ecoimpacts represented by a score of a sustainability assessment tool. This top down approach requires the clarification of the type of impacts of building assessment assessed in terms of ecological impact

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and environmental performance. The rationale behind criteria should be related to the value system of the context applied [24]. In order to face the uniqueness and complexity of sustainable architecture the application of case studies [25] to make a choice for sustaianbl assessment tools is an important step in the design process.

6. ACKNOWLEDGEMENTS The foundation “Stichting Promotie Installatietechniek (PIT)” supported this research.

7. REFERENCES [1] Holzer D.C.C., 2009, Sense-making across collaborating disciplines in the early stages of architectural design,PhD thesis, School of Architecture and Design Design and Social Context Portfolio, RMIT University, October 2009 [2] Kalay Y.E., 1998, P3: Computational environment to support design collaboration Original Research Article Automation in Construction, Volume 8, Issue 1, November, 37-48 [3] Holzner D., Downing S., 2010, Optioneering, A new basis for engagement between architects and their collaborators, Arxhitectural Design, Vol.80, Is. 4, 60-63 [4] Buur J., Andreasen M.M., 1989, Design models in mechatronic product development, Design Studies, Vol 10 No 3 July [5] Hartog, J.P.den, 2003, Designing indoor climate, a thesis on the integration of indoor climate analysis in architectural design, thesis manuscript dated 01/09/2003, Delft University [6] Mourshed M., Kelliher D., Keane M., 2003, ArDOT: A tool to optimize environmental design of buildings. Proceedings of IBPSA 2003. [7] Loftness, V., Hartkopf, V., Poh, L.K., Snyder, M., Hua ,Y., Gu, Y., Choi, J., Yan,g X. 2006. Sustainability and Health are Integral Goals for the Built Environment, Proceedings Healthy Buildings 2006, Lisbon, Portugal, June 4-8. [8] Loftness, V., Hartkopf, V., Gurtekin, B., Hua, Y., Qu, M., Snyder, M., Gu, Y., Yang, X. 2005. “Building Investment Decision Support (BIDS™) —Cost-Benefit Tool to Promote, High Performance Components, Flexible Infrastructures & Systems Integration for Sustainable Commercial Buildings and Productive Organizations,” 2005 AIA Pilot Report on University Research, pp. 12-31. [9] Hendrickson, C., Conway-Schempf, N., Lave, L. and McMichael, F. 2008, Introduction to Green Design, Green Design Initiative, Carnegie Mellon University, Pittsburgh PA, accessed 28 may 2008, www.ce.cmu.edu/GreenDesign/gd/education/gd edintro.pdf [10] Roozenburg, N. and Eekels J. 1995. Product design: Fundamentals and methods, Wiley,

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Chichester. [11] Derelöv, M. 2004, On Conceptual Design Reliability, Linköpings University, Thesis No.1121, Licentiak [12] Thabrew, L., Wiek A., Ries, R. 2008. Environmental decision making in multistakeholders contexts: applicability of life cycle thinking in development planning and implementation, J Clean Prod (2008), doi:10.1016/j.jclepro.2008.03.008 [13] Lony, R.J.M., Molenaar, D.J., Rietkerk J., Schuiling, D.J.B.W., Zeiler, W., Brun,k M.F. 2006, Comparison between Dutch and German buildings, Proceedings VDI Tage der Gebäudetechnik, January 31 – february 1, Leonberg. [14] Lee, W.L., Burnett, J., 2007, Benchmarking energy use assessment of HK-BEAM, BREEAM and LEED, Building and Environment 43 (2008) 1882-1891 [15] Fowler, K.M., Rauch, E.M., 2006, Sustainability Building Rating Systems Summary, Rapport DEAC05-76RL061830, Pacific Northwest national Laboratory, Battelle [16] Kalay Y.E. 1999. Performance-based design, Automation in construction 8 (1999) 395-409 [17] Løken, E. 2007. Multi-Criteria Planning of Local Energy Systems with Multiple Energy Carriers, PhD Thesis Norwegian University of Science and Technology, Trondheim, April 2007. [18] Pohekar, S.D. and Ramachandran, M. 2004. Application of Multi-Criteria Decision Making to Sustainable Energy Planning - a Review, Renewable and Sustainable Energy Reviews, vol. 8 (4), p. 365-381 [19] Hobbs, B.F..and Meier P.M. 1994. Multicrerion methods for resource planning: an experimental comparison. IEEE Transactions on Power Systems 9(4):1811–7. [20] Crawley , D., Aho, I., 1999, Building environmental assessment methods: applications and development trends, Building Research & Information (27(4/5), 300-308 [21] Soebarto, V.I., Williamson, T.J., 2001, Multicriteria assessment of building performance: theory and implementation, Building and Environment 36, 681-690 [22] Ding, G.K.C., 2008, Sustainable construction – The role of environmental assessment tools, Journal of Environmental Management 86, 451464 [23] Block B., 2009, Green Building Standards Under Construction , Worldwatch Institute, Published August 27, 2008, Green Building, e-journal, 2009, Vol 3(3). [24] Podeva M.G.Z., 2009, Sustainability as driver of architectural practices, PLEA 2009, Quebec [25] Trebilcock M., 2009, 592: Learning from practice: a model for integrating sustaianbel design in architectural education, PLEA 2008, Dublin

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Analyzing the Application of Energy Efficiency Labelling to Hotel Buildings MYRTHES MARCELE FARIAS DOS SANTOS, LUCIANA HAMADA, RICARDO WARGAS DE FARIA Sebrae/RJ, Innovation and Technology Access Unit, Rio de Janeiro, Brazil ABSTRACT: Most Brazilian buildings have low performance in terms of energy, since they received little attention (or none) concerning energy efficiency. In 2009, new perspectives to change this situation emerged, due to an initiative by the Federal Government, that established the necessary regulations for energy efficiency labelling in buildings, and broadened the Brazilian Labelling Program, which, up until then, encompassed only machinery and equipment. Never before had that happened in Brazil: conditions were defined for the classification of commercial buildings according to their energy efficiency, considering lighting and airconditioning systems, and the architectural envelope. The major purpose of this article is to analyze, from a business point of view, the compliance with the new regulations for energy efficiency labelling in hotel buildings, where small businesses are predominant. Hotels have been targeted for large investments, since they have become the pillars of Brazil’s project to welcome tourists during the 2014 World Cup and the 2016 Olympic Games. The outcome of this article is a broad analysis on the application of new regulations for labelling the level of energy efficiency of the hotel business, based on two perspectives: the external environment (opportunities and threats) and the internal environment (strengths and weaknesses). Keywords: energy efficiency; commercial buildings; labelling; small businesses; hotels.

1. INTRODUCTION The service sector, which includes the hotel business, employs a large portion of the population and accounts for a large measure of Brazil´s GDP and consumption of electric energy. In 2009, in the midst of the global financial crisis, Brazil´s GDP suffered a decline of 0.2%, after experiencing a gain of 5.1% in 2008. However, the service sector stood out as the only sector to show growth, at a rate of 2.6%, and increased its share of the whole economy to 68.5%. The Industrial sector, which comprises around 25.4% of the economy, showed negative growth of -5.5% [1]. Over the coming years, the service sector is expected to continue its growth trend, averaging 4.3% a year over the 2010-2014 period, putting Brazil´s economy in synch with the trends in developed economies, where services are gaining increasing importance in the generation of a country´s wealth. The growth trend in the services sector has a direct impact on the consumption of electric energy in the sector, which is likely to be above the national average. According to the Ten Year Energy Expansion Plan 2008-2017, consumption in the business sector, which includes services, is expected to grow at an annual average rate of 6.9%, and thus the sector will become the biggest consumer, increasing from 15.1% presently to 18.3% in 2017 [2]. In the world today, it can be noted that companies and businesspeople in all sectors are making increasing efforts to provide quality service in response to the needs and desires of their customers, even if, oftentimes, this is associated with unnecessary costs and the wasting of all kinds of resources. Thus, in hotels, the major components of electric energy consumption are in climate control and lighting, which are closely linked to the comfort

requirements of habitual users (employees) and occasional users (guests). The amount of electric energy consumed in climate control and lighting depends, among other factors, on the technology used, operating conditions and systems maintenance, and the way the building is occupied. However, it depends importantly on the construction characteristics of the building: whether they are suitable or not for local climate conditions. Although architectural solutions for energy efficiency have greater potential when adopted during the design phase of the building, there are economically viable ways to make architectural modifications to buildings already constructed. According to data in Eletrobras´ Procel – the National Program for the Conservation of Electric Energy, the potential for energy savings in new buildings is around 50%, and 30% for existing buildings [3]. In this way, the adoption of architectural strategies that are specific for each situation and focus, among other things, on the shape of the building, the physical properties of the construction materials, and the transmission of natural light, allows better energy performance in a hotel establishment, in that the use of energy to satisfy the comfort of guests will only occur at times when conditions in the external climate are unfavorable. Architectural strategies can also be combined with artificial systems which use new technology to avoid wasting energy, such as the automatic closing of windows when air conditioners are in use, or the installation of photo-electric sensors which reduce the amount of illumination when there is natural light. In addition to reducing energy costs through the implementation of such measures, today employers can obtain the “National Label of Energy Conservation” (Etiqueta Nacional de Conservação de Energia - ENCE), which classifies commercial buildings with respect to energy efficiency, taking

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three systems into account: lighting, air conditioning, and architectural envelope (“the skin of the building”).

2. REGULATIONS FOR ENERGY EFFICIENCY IN BUILDINGS The new Brazilian regulations for energy efficiency, which created the labelling of buildings, were established by Inmetro, the National Institute of Metrology, Standardization, and Industrial Quality and Procel, through the publication of two complementary ordinances. o • Ordinance n 372, dated 17/09/2010, which ratifies the “Technical Regulation for the Quality Level of Energy Efficiency in Commercial, Service and Public Buildings” (RTQ-C); and o • Ordinance n 185, dated 22/06/09, which ratifies the “Regulation for the Assessment of the Level of Compliance of Energy Efficiency in Commercial, Service and Public Buildings” (RAC-C). RTQ-C specifies the technical criteria for the classification of new and existing buildings with respect to energy efficiency; the classification can vary from level “A” (more efficient) to level “E” (less efficient). The requirements of RTQ-C are to be assessed by an inspection entity accredited by Inmetro, as described in RAC-C, which contains all the necessary procedures to obtain authorization for the use of the ENCE. RAC-C contains forms, models of spreadsheets, terms of commitment, which will enable the building to be submitted for labelling. Labelling and inspection, as mechanisms to assess the level of energy efficiency in buildings in Brazil are a result of the emergency measures taken during electric energy rationing which was experienced in 2000-2001. With the approval of the “Energy Efficiency Law” (Lei de Eficiência Energética o - Law n 10.295, dated 17/10/2001), whose course in the National Congress began in 1990, and the Decree o n 4.059, dated 19/12/2001, which regulates it, minimal levels for energy efficiency were established for machines and consumer appliances made or sold in Brazil; the same was applied to building structures, and, in addition, the need for “technical indicators and specific regulation” was indicated, in order to establish obligatory levels of efficiency. 2.1. National Label of Energy Conservation (ENCE) for Buildings The ENCE for buildings was introduced as a voluntary measure, with a view to preparing the civil construction market to gradually absorb the new method of classification; but, it will likely become obligatory for new buildings at a yet to be determined date. It is directed to commercial, public, and service buildings, climatized in whole or in part, artificially or naturally, with workspace over 500 square meters or serviced by voltage equal to or higher than 2.3kV (tariff group A). This restriction in the regulations excludes some micro and small enterprises, despite the fact that the methodology developed for the calculation of energy efficiency is applicable to buildings of all types and sizes. To be eligible for labelling, the building must have an electrical circuit which can be centrally controlled

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according to its final use: lighting, air conditioning, among others. If this requirement cannot be met, the highest possible rating for the building is level “C”. There are exceptions: hotels with circuits that are turned off automatically when the guest leaves the room or buildings whose date of construction precedes the publication of RTQ-C. The classification of the level of energy efficiency for the building can be: • General: encompassing the three systems (envelope, lighting and air conditioning) plus possible improvements through innovative technology, cogeneration etc. • Partial: separately for each of the systems. In order to obtain a general classification for the building, the efficiency of each system must first be calculated, resulting in partial ratings. An equation weighs the individual systems, through an established weighting system, resulting in a final rating for the building. The weightings are as follows: envelope, 30%; lighting, 30%; and air conditioning, 40%. The number of points obtained determines the partial classifications or the general classification to be presented in the ENCE provided to the building. 2.2. Architectural Envelope Specifically with respect to the architectural envelope, RTQ-C prescribes the calculation of a Consumption Indicator (IC), which predicts how the envelope of the building will impact the building´s energy consumption, taking into consideration: the area of the windows, the existence or not of solar protection and how extensive it is, the type of glass used, the dimensions of the building, and the Brazilian bio-climate zone, as established in ABNT NBR 15.220:2005 - Thermal Performance of Buildings. The IC obtained is evaluated against a scale, which considers Brazilian construction patterns, and which is divided into numbered intervals determining the level(s) of energy efficiency. The lower the IC, the more efficient the building: that is, the less the envelope exposes the interior of the building and less heat is exchanged between the interior and exterior. Thus, envelopes with less heat exchange imply less heating of the building in hot climates (through solar radiation, temperature), or less heat loss in cold climates (through infiltration, temperature differences, for example). As a result, less energy is consumed in artificial climate control of the building´s interior. After the IC of the envelope is calculated, it is necessary to check if the specific prerequisites (thermal transmittance and absorptivity of the roof and external walls, as well as natural light) are satisfied for the level of efficiency indicated. The higher the intended level, the more stringent are the prerequisites.

3. PRESENT PROFILE OF THE HOTEL SECTOR The hotel facilities vary according to the resources and operating focus of each establishment, with services offered thus ranging from basic food and accommodation, to luxury services, and/or facilities

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and services to handle conferences and events. Thus, there is great diversity among the establishments comprised in this segment, and, similar to other tourist activities, most of the business is conducted by small companies, normally run as family businesses. According to the Brazilian Statistics Institute IBGE, there are 25,000 hotels and like establishments in Brazil, engaged in the business of short term lodging through hotels, motels, and inns; 42% are concentrated in the Southeast Region and 22% in the Northeast Region [4]. Of this universe, 70% are micro-enterprises, and 27% are small enterprises, providing around one million rooms. By contrast, the ten leading hotel chains presently operating in Brazil, led by the French chain Accor Hotels, together, provide only 60,000 rooms [5]. The hotel sector is labor intensive, providing approximately 284,000 jobs, with micro and small enterprises accounting for about 68% of the total. It should be emphasized that the cost of generating a job in the hotel industry is one of the lowest in the Brazilian economy, at an average of R$16,000 (Brazilian real). By comparison, the cost of generating a job in civil construction or the textile industry is almost double at around R$28,000 [6]. It is worth pointing out, further, data surveyed by Jones Lang LaSalle Hotels, which shows a growth of 6.7% in “RevPAR” (revenue per available room) for hotels in 2009 [7]. With respect to utility costs (electricity, water, and others), depending on the type and size of the hotel, the same study shows that such costs vary between 17.35% and 27.94% of operating expenses, with the higher percentages in hotels with daily room rates below R$ 155 (Brazilian real). 3.1. Electric Energy Consumption and Conservation Potential According to data from the National Energy Balance (BEN - Balanço Nacional de Energia), the business sector, which includes hotels, consumed 64,329 KWh of electric energy in 2009 [8]. Data from Procel show that the greatest uses of electric energy in the business sector were for climate control (40%) and lighting (19%) [9]. For hotel establishments these uses together accounted for 59% of the total electric energy consumption [10], as shown in Table 1 below. Table 1: Electric Energy Consumption by end-use (%) – Business Sector and Hotels – Brazil (2006)

Climate control

Commercial Sector 40%

End-use

Hotels 41%

Lighting

19%

18%

Equipment

15%

14%

Other

26%

27%

With respect to the potential for energy efficiency in the use of electric energy, the commercial sector is among those with the greater possibilities. Based on the analysis of the technical and economic characteristics of the energy efficiency measures presently available in the marketplace, and on the

incentive policies which can be adopted to facilitate their use, the Plano Nacional de Energia - PNE (National Energy Plan) shows in its three scenarios a greater potential for reduced consumption, as shown in Table 2 [11]. Table 2: Potential for Reduced Electrical Consumption by Sector (%) – Brazil (2007)

Sector

Energy

Scenarios Technical

Economic

Market

Industrial

41%

21%

12%

Commercial

58%

29%

16%

Residential

32%

15%

6%

With specific reference to the energy efficiency potential in the hotel industry, a study conducted by the Programa de Planejamento Energético of COPPE/UFRJ divides the industry into three groups of facilities, and estimates for each one the following technical potential for reducing electric energy consumption: 26% in the sophisticated group (13.2 2 kWh/month/m ), 21% in the basic group (3.45kWh 2 /month/m ) and 26% in the very basic group (1.35 2 kWh/month/m ) [11].

4. CONSTRUCTION PATTERNS IN HOTELS Although Brazil lacks studies on the construction patterns which are most representative of buildings and their various uses, two important nationwide studies on electric energy consumption have already been made, covering hotels, among others. One of these studies is the “Survey of Equipment Ownership and Habits of Energy Consumption” (Pesquisa de Posse de Equipamentos e Hábitos de Consumo de Energia), conducted by Procel since 1988, with a sampling that represents 92% of the market. In the business sector, around 5,600 facilities were surveyed, trying to maintain the same number of samples for each utility company and sector of activity. For the purposes of the survey, 16 commercial activities using Low Voltage (LV) and 11 using High Voltage (HV) were selected [9]. Of the hotels and motels covered, there was effective participation of 381 establishments, 6% in LV and 21% in HV (176 hotels and 22 motels) [10]. From the commercial buildings surveyed, it was observed that in 67.4% the façade was predominantly masonry, followed by glass (predominant in 11.3% of the cases). An absolute majority of the buildings had roof types which accumulated heat, with slab roofs (43.2% of the cases) and fiber cement roofs (17.5% of the cases) most commonly found in the structures that were surveyed. For the windows, simple glass, without the use of sun screens, was most commonly used (58.1% of the cases). Darkened glass was used in 11.8% of the cases. Lastly, it can be observed that only 15.7% of the buildings had some kind of external protection against insolation; thus there is room for architectural modifications in those regions, where the use of shading elements placed could provide greater thermal comfort and less use of air conditioning. The other study, conducted on a national scale, was a field study of the physical characteristics and

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To analyze the application of new regulations for labelling the level of energy efficiency of the hotel business, we have chosen to develop a SWOT Matrix (Strengths, Weaknesses, Opportunities and Threats). This is a tool widely accepted in the market for evaluating a range of scenarios (or in the analysis of environments), and it is used as a base for management and strategic planning in a corporation or company, but it can also be used for any kind of scenario analysis. From a business perspective, the analysis is organized around two perspectives: the external environment and the internal environment. Table 3, which shows the opportunities and strengths in the application of labelling to hotel buildings, and Table 4 which shows threats and weaknesses, follow.

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Opportunities

External Environment • Consolidation over the long term of efficient energy use in the country; • Reduction of electric energy consumption; • Postponement of the need for investments in power generation; • Improvement in city building codes; • Development of sectorial indicators of energy efficiency; • Improvement in the quality of hotel accommodations in Brazil; • Incorporation of sustainability concepts in buildings; • Opening of a new market niche for professionals.

Internal Environment • Better understanding of one´s facilities; • To be more energy efficient; • Possibility of reducing electric energy costs , thus reducing daily rates; • To become more competitive; • To obtain advantages for labeled hotels - based on the marketing of sustainability; • To add value to services offered.

Table 4: Threats and Weaknesses in the Application of Labelling to Hotel Buildings

Threats

External Environment • Excess of regulatory details could hinder market acceptance; • No labelling of buildings with usable space below 500m2; • Lack of qualified professionals to apply new regulations; • Lack of financing sources that favor labelling; • Few entities to issue the labelling and entities are tied to universities.

Internal Environment • High refitting costs for projects already constructed; • Increased costs from hiring specialty consultants; • Lack of clarity with respect to the benefits obtained from labelling.

Weaknesses

5. APPLICATION OF LABELLING TO HOTEL BUILDINGS

Table 3: Opportunities and Strengths in the Application of Labelling to Hotel Buildings

Strengths

energy use in non-residential buildings. This study was conducted by the Laboratory of Energy Efficiency of Buildings (“Labeee”), of the University of Santa Catarina (UFSC), which helped develop energy efficiency regulations for buildings in Brazil. A specific methodology for surveying the common characteristics of buildings was developed, making use of photographic and on site approaches. The photographic survey recorded 1,103 buildings in the metropolitan areas of five Brazilian cities: Recife, Salvador, Belo Horizonte, São Paulo and Florianópolis, and provided typical volumetric dimensions and other characteristics relating to the exteriors of the buildings, which enabled the construction of representative models of the buildings typically found in urban settings. Next, the onsite survey collected physical and usage characteristics of the interiors of the buildings, of examples of buildings in Florianópolis according to their specific activity, whose building exterior types were most similar to the models generated. Of the total number of buildings in the study, the largest number of samples were big offices, which accounted for 26.2% of the total, followed by small stores (14.1%). Eighty two hotels and eleven inns were in the study, representing 8.2% of the total [12]. The architectural features found in hotel buildings were as follows: in their façades, the majority of the hotels had a window area of 21-40%; also in the façades, there was a secondary but still significant characteristic occurring in less than 20% of the cases, that is a small opening in the façades. With respect to the predominant color of the glass, almost 50% of the hotel buildings used colorless glass, while grey was the predominant color in almost 30% of them. The existence of solar protection is not common in the majority of the buildings, in that the Vertical Shadow Angle (VSA) referring to the existence of horizontal solar protection in the openings was found in few buildings. Of those buildings which had them, the VSA of up to 25% was most common; angles above this, that is, with greater shading capacity were not common. Even less common was the vertical protection, or Horizontal Shadow Angle (HAS), which thus can be considered irrelevant.

Our definition of the external environment corresponds to the macro-environment of the hotel industry, that is, the segments which affect or are affected by it, such as the governmental authorities, other sectors like tourism and civil construction, professionals of several levels and society as a whole. The internal environment represents just the hotel industry. Below is a detailed explanation of each of the items covered in the analysis. 5.1. Opportunities – External Environment • Consolidation over the long term of efficient energy use in the country – having been adopted in more than 25 countries [13], labelling and the establishment of standards for equipment and facilities are proven techniques for improving the efficient use of energy in a country. • Reduction of electric energy consumption – the more efficient use of energy in buildings has a direct impact on the reduction of final power consumption, especially in lighting and air-

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

conditioning systems. Estimates made in other countries show 4% savings in the consumption of electric energy as a result of the application of labelling [13]. • Postponement of the need for investments in power generation – the partial reduction of energy consumption in buildings, which account for around 50% of energy consumption in Brazil [9], helps to defer the expansion of electric power generation, without compromising the quality of services provided to the end users. The costs associated with a labelling program are significantly less than the cost of expanding the electric power system. • Improvement in city building codes – the establishment of minimum energy efficiency levels for buildings on a national scale leads to the revision of local building codes. A city building code could even suggest materials and construction types which are different from those used regularly, incentivating the market to become increasingly more efficient. • Development of sectorial indicators of energy efficiency – setting up a database on the Brazilian buildings which have been labeled will allow the development of technical indicators, both quantitative and qualitative, which can contribute to the development of public policies and the creation of benefits for several sectors, including hotels and small businesses. • Improvement in the quality of hotel accommodations in Brazil – to reach the required levels of energy efficiency, the buildings will have to undergo modifications and modernization of their facilities. This will result in more than just energy gains, such as improvement in guest comfort and in the quality of the accommodations, which in turn will attract more tourists, especially from abroad. • Incorporation of sustainability concepts in buildings – the concepts of sustainability, added to those of energy efficiency, involving new construction techniques and materials, also lead to greater efficiency in the buildings consumption of other resources. In hotels, the consumption of water and energy are closely linked, as it is common to adopt a program of energy efficiency which involves reduction of wastage as a whole. • Opening of a new market niche for professionals – the labelling of buildings can expand the market for professionals in civil construction, since it promotes the introduction of new concepts in architectural and modification projects, as well as the audit of efficient buildings. Thus, it functions as a tool for developing new niches in the market. 5.2. Strengths – Internal Environment • Better understanding of one´s facilities – the analysis of the hotel facilities for the purpose of labelling documents the operating conditions of the enterprise and its actual energy needs, in addition to indicating the opportunities for reducing waste and the viability of performing architectural modifications. • To be more energy efficient – the implementation of energy efficiency solutions in order to obtain the labelling is the most effective way to simultaneously optimize the facilities and improve the

quality of services offered, mainly in the lighting and air-conditioning systems. • Possibility of reducing electric energy costs, thus reducing daily rates – the incorporation of sustainability concepts and energy performance parameters into the enterprise will lead to savings in consumption and in the costs of energy and other resources. • To become more competitive – the hotel business which adopts labelling as a quality requirement for its facilities will have lower operating expenses, resulting in a lower daily rate. Therefore it will be possible to offer a higher quality service at a more competitive price. • To obtain advantages for labeled hotels based on the marketing of sustainability – the businesses that are labeled can display this qualification, making it a point of difference in relation to competitors. This differential might guide the development of a market strategy directed to sustainability and social responsibility, attracting a more demanding target public which is willing to pay more for this. • To add value to services offered – classification at a higher energy efficiency level will allow a business to add value to the services it offers, since this might make it attractive to groups of guests who chose services that address sustainability issues. 5.3. Threats – External Environment • Excess of regulatory details could hinder market acceptance – the process for obtaining a label involves methods and technical requirements to make a precise evaluation of the level of energy efficiency in buildings, which has never been done before in Brazil. For this to be accepted by the market, the training of professionals and the promotion of partnerships with manufacturers is needed. • No labelling of buildings with usable space 2 below 500m – the opportunities and competitive advantages created by the possibility of labelling remain restricted to the large and medium size companies, which comprise a lesser share of the hotel sector. For future actions, it would be necessary to correct this limitation by the inclusion of a greater universe of companies, since the methodology is already established and can be applied to establishments occupying smaller areas. • Lack of qualified professionals to apply new regulations – the lack of professionals, qualified in energy efficiency in the civil construction sector, could hinder the application of labelling, unless there is greater investment in training and capacity building, as well as In partnerships with universities to convey the methodology proposed in the labelling process and the classification of efficient buildings. • Lack of financing sources that favor labelling – there are few sources of attractive financing for the modification of buildings for the purpose of implementing energy efficiency measures. This could make the attainment of the required levels of efficiency unviable. • Few entities to issue the labelling and entities are tied to universities – the time spent by interested companies to obtain labelling has been too long,

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because of the bureaucracy involved, and because the established entities are tied to university structures which lack the dynamism that the market needs for its full functioning. 5.4. Weaknesses – Internal Environment • High refitting costs for projects already constructed – the majority of Brazilian buildings are the result of an architectural style which does not take into consideration the natural characteristics of their surroundings, which makes them inefficient. Often the costs for adjustment and making them more efficient after construction are high, which can make labelling unviable. • Increased costs from hiring specialty consultants – the implementation of energy efficient measures and the obtaining of a label require advice and monitoring on the part of specialists in the field. Hiring these professionals involves increased costs. • Lack of clarity with respect to the benefits obtained from labelling – the hotel business has still not grasped the advantages of energy efficiency in its market because of the low level of dissemination of information on the various gains that can be obtained. Very little has been invested in the dissemination of energy efficiency labelling for buildings through the corresponding sectorial channels. This can become an impediment to its application.

6. CONCLUSION Despite the fact that the new regulations are considered difficult to apply to buildings which have already been constructed, labelling is recognized as an effective tool for achieving energy efficiency in the country in the long term, and for promoting the move of the construction industry to standards of efficiency. Another aspect is the fact that labels are not given to 2 buildings with work space less than 500m , thus excluding a portion of the small hotel businesses. For them, the concepts of sustainability and architectural strategies should be encouraged more strongly, since small enterprises have been proven to be more flexible in adjusting to the rapid changes of our times and to the incorporation of new concepts. Since big sports events, such as the 2014 World Cup and the 2016 Olympic Games, have been scheduled for the next few years, various investments are forecast for the hotel sector in Brazil. One which is worth pointing out is the BNDES program ProCopa Turismo, a line of financing which encourages energy efficiency in the expansion and modernization of hotels. This financial incentive will make the market that targets the hotel segment (architectural and consulting firms, construction companies), address more appropriately all environmental issues to be considered in the implementation of the enterprise and the application of energy efficiency regulations. For the entrepreneurs, the principal benefit from obtaining a level “A” label (more efficient) for their business is the possibility of offering more sustainable services from an environmental perspective, to those guests who look for this feature, as well as the positive results which will arise from the increased

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awareness of the theme of energy efficiency by the users of such hotel buildings (employees and guests).

7. REFERENCES th

[1] www.bcb.gov.br. Accessed on April 8 , 2010. [2] EPE - Empresa de Pesquisa Energética, Ministério de Minas e Energia, Plano Decenal de Expansão de Energia 2008-2017, Rio de Janeiro (2009), 2v. [3] http://www.eletrobras.com/procel. Accessed on May 10th, 2010. (Procel - Programa Nacional de Conservação de Energia Elétrica) th [4] www.ibge.gov.br. Accessed on May 6 , 2010. Instituto Brasileiro de Geografia e Estatística [5] E. A. Bojar and L. Goldner, Análise Setorial da Indústria Hoteleira no Brasil, Volume 3, Amazonas Press, São Paulo (2006). [6] FIPE - Fundação Instituto de Pesquisas Econômicas, Sebrae, Ministério do Turismo, Meios de Hospedagem, Estrutura de Consumo e Impactos na Economia, São Paulo (2006). [7] Jones Lang, LaSalle Hotels, Hotelaria em Números, Brasil 2010, São Paulo (2010), 20. th [8] www.ben.epe.gov.br. Accessed on August 12 , 2010. [9] Eletrobras, Procel – Programa Nacional de Conservação de Energia Elétrica, Pesquisa de Posse de Equipamentos e Hábitos de Consumo de Energia, Ano Base 2005, Classe Comercial, Alta Tensão, Estudo Completo, Rio de Janeiro (2008), 160. (Survey of Equipment Ownership and Habits of Energy Consumption) [10] Eletrobras, Procel – Programa Nacional de Conservação de Energia Elétrica, Pesquisa de Posse de Equipamentos e Hábitos de Consumo de Energia, Ano Base 2005, Classe Comercial, Alta Tensão, Relatório Setorial: Hotéis / Motéis, Rio de Janeiro (2008), 13. (Survey of Equipment Ownership and Habits of Energy Consumption) [11] EPE - Empresa de Pesquisa Energética, Ministério de Minas e Energia, Plano Nacional de Energia 2030, Rio de Janeiro (2007), 12 v. [12] J. C. Carlo, Desenvolvimento de Metodologia de Avaliação da Eficiência Energética do Envoltório de Edificações Não-residenciais, Tese de Doutorado do Programa de Pós-Graduação em Engenharia Civil, Universidade Federal de Santa Catarina, Florianópolis (2008). [13] A. G. P. Garcia, Impacto da Lei de Eficiência Energética para Motores Elétricos no Potencial de Conservação de Energia na Indústria, Dissertação de Mestrado do Programa de PósGraduação em Engenharia, Universidade Federal do Rio de Janeiro, Rio de Janeiro (2003).

CLIMATIC, WATER AND BIODIVERSITY CONTEXT

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

A PATTERN LANGUAGE DESIGN TOOL FOR WATER EFFICIENT GARDENS A Knowledge Based Computer-Aided Design (KBCAD) tool for water efficient landscape design Daphna DRORI AND Edna SHAVIV Faculty of Architecture and Town Planning, Technion-Israel institute of Technology, Haifa, Israel

ABSTRACT: A Knowledge Based Computer-Aided Design Tool was developed for the process of designing water efficient gardens, and is applicable at any stage of the design process. The design tool is based on the "Pattern Language", which is characterized by a decision making process that reflects customized choices and flexible implementation. To realize water efficiency, emphasis is put on the bioclimatic design of the garden for the comfort of the plants and the people. The tool directs the planner to adjust the design to the autochthonous conditions of site and recommends a variety of options for effective and efficient design. The tool consists of a qualitative part and a quantitative one, thus enable to evaluate the qualitative design with quantitative measurements. The proposed tool is demonstrated by case study, whose results shows a tremendous reduction in water consumption of more than 50% in total, thus proofing the effectiveness of it and infers to the amount of possible water consumption reduction. Keywords: water efficient gardens, water consumption reduction, bioclimatic design, KBCAD tool, pattern language.

1. INTRODUCTION The water issue is now a crucial matter around the globe more than ever. There is a constant growth in water demand due to the increase in the population and the rise in the standard of living, which is expressed in the data of the Gross National Product (GNP). 1.1. The water crisis in Israel After continuity period of five years of drought in Israel (2004-2009) and an average year (2010), water crisis is an existing fact. The Israeli government raised the water cost in order to reduce consumption. In the residential sector, the base tier cost is sufficient, in the best case, only for indoor use. The garden use is double the cost, and many lawns were irrigated insufficiently and turned dry and yellow, or died completely. However, the way to implement water efficiency policy is not necessarily by eliminating the "green", but by proper design of the gardens. In an era of sea water desalination, theoretically there won't be shortage in potable water in the near future, but 1 cubic meter of desalinated water has an energy rate of 3.75 kW/h. Thus, a reduction in water consumption contributes to the reduction in energy consumption.

influences domestic water consumption [1]. (See black line in Figure 1). A second factor influencing domestic water consumption is the urban form. There is a correlation between the GNP per capita and the demand for private houses with gardens, which increases the irrigation requirements. In countries like the U.S and Canada, where low density housing type are dominant building pattern, we see increased domestic water consumption (See dashed line circles in Figure 1). We argue that as far as the GNP is increasing permanently, the increase in the domestic water consumption is liable to grow also. Due to this, water crisis is expected to strengthen, and water efficient design is significantly essential.

1.2. Residential water consumption Trying to inquire which are the factors determining residential water consumption, it is clear that there is a correlation between water consumption in household and the data of GNP per capita. In other words, the standard of living strongly

Figure 1: Correlation between Water Consumption in Household and GNP Per Capita

Another major factor influencing water consumption is the climate. It is surprising at first to see that in countries like Spain and Israel the domestic water consumption is similar to that of

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France and Sweden. This is due to the fact that in hot countries, irrigation of garden is required almost all year round (See black circle in Figure 1). 1.3. Climate and garden water usage The ratio of garden water usage to total domestic water consumption is different from place to place. In the U.S for instance, there are states like Pennsylvania where outdoor use constitutes only 7% of total water consumption, and there are states like California where it constitutes 44%. The average in the U.S is in fact, 32% [2]. The differences in this case derive from a combination of the three factors as aforementioned. Comparing to Pennsylvania, the standard of living is higher, the dominant urban form is that of private houses with gardens, and the climate of the state of California is dryer. All of these factors encourage the increase in the ratio of garden water usage to total domestic water consumption. 1.4. Proper architectural design In a research performed in Barcelona (Spain) [3] it was discovered that differences in garden design effect water demand significantly. The preferred "Atlantic garden", based on green turf grass as the main component, on a traditional "Mediterranean garden" based on autochthonous, less consuming plants cause the garden water consumption to increase in 40%. A proper architectural design process of the garden should be an integration of paved areas within the landscape, a selection of water efficient plants and efficient and effective irrigation systems. In order to design effectively, it is essential to perform a climate analysis and adjust the design to the local and unique conditions of the place. These two factors, the climate consciousness and the effective and efficient design can contribute a tremendous reduction in water consumption of more than 50% in total. Moreover, the designer has the professional ability and the professional ethics to maximize the water conservation of the garden. In order to cope with efficient landscaping, a Knowledge Based Computer-Aided Design (KBCAD) tool was developed and can be implemented in the various design stages. Chapter 2 deals with the methodological aspects of the described research. Chapter 3-4 present the tool: the qualitative part as well as the quantitative one. The proposed tool is demonstrated in Chapter 5 by a case study that shows the effectiveness of it

2. A PATTERN LANGUAGE DESIGN TOOL The Knowledge Based Computer-Aided Design (KBCAD) tool that was developed, derives its methodology layout from "The Pattern Language" [4] conceived by Christopher Alexander and implemented by Edward Mazria in “The Passive Solar Design Handbook” [5] for the theme of Passive Solar Architecture. 2.1. "The Pattern Language" The language is composed of elements called patterns. The patterns describe variables and

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problems one should address during the different design stages, as well as options for solutions. The pattern language is a holistic design approach, with a decision making process that is not linear or hierarchical, but rather carried out according to need. Thus, the decision making pattern is a semilattice offering infinite possibilities and unique implementation for every project, like a new language for each design (Figure 2).

Figure 2: The semi-lattice navigation order [7]

The advantage of choosing the pattern language as a methodological concept is evident. This way of decision making process is more adjusted and convenient for the implementation of guidelines in the design process, because it is carried out not as checklist but as links based on the planner's requirements.

3. KBCAD TOOL FOR EFFICIENT DESIGN OF GARDENS Originally, "The Pattern Language" [4] and "The Passive Solar Energy Book" [5] are hard copy books. Our efficient landscape design tool is a KBCAD tool therefore it is more user friendly than a hard copy book. Figure 3 illustrates the structure of the data in this tool. As appears, the information is organized in hierarchy but the concept of navigation is nonlinear one.

Figure 3: The navigation through patterns in the KBCAD tool

Each of these cells (Figure 3) contains information and recommendations for its specific subcategory. Typically, one can go in his decisionmaking process from top to bottom in each of the six main branches. Alternatively, he can make a semilattice navigation through information, in a manner which reflects customized choices. 3.1. The patterns layout Basically, the KBCAD tool is divided into six main branches, which are: Landscape Design, Irrigation, Vegetation, Agro-technical Methods, Runoff and Non Potable Water. The "Landscape Design" branch (Figure 4) contains four branches. It deals with the selection of

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

a "Combination of Plants" for the garden and the integration of "Built Elements" within it. Other important branches are the "Field of Vision", which assists the planner in minimizing the vegetation areas without spoiling the beauty of the garden, through the creation of an aesthetic illusion of a full garden, and "Environmental Conditions".

The "Vegetation" recommendations for plants' selection, and large diverse group (Figure 7).

branch of patterns contains choosing native or adopted plants which belong to the of "Water Efficient Plants"

Figure 7: The "Vegetation" branch Figure 4: The "Landscape Design" branch (level 1 only)

We would like to look more deeply at the branch "Environmental Conditions". It is important to indicate that the climatic perspective in water efficient gardens design, is similar to bio-climatic buildings design, and is the essence of the process. The design should start by analyzing the environmental conditions and refer to the unique characteristics in the proposed design. The planning should respond to the local nuances, obtain maximum adjustment of the plants to the climate and encourage the most sustainable solution for irrigation requirements. Therefore, emphasis was put on the bioclimatic design of the garden for the comfort of the plants and the people, which is indicated by the "Environmental Conditions" pattern that contains in Level 2: "Climate", "Micro-Climate", "Orientation", "Evapotranspiration", as well as "Soil" and "Topography" (Figure 5). Through these patterns the tool directs the planner to adjust the design to the climate and autochthonous conditions of the site and recommend a variety of options for effective and water efficient garden suited the particular climate

"Agro-technical methods" are a set of advisable techniques for amending durability of soil and plants' health in the garden, like "cultivation", "Mulching", "Mowing" and "Compost" (Figure 8). These patterns are effective for maximizing the water conservation of the garden and for minimizing the maintenance of it in the long run as well. Thus, promoting a sustainable garden in its wide definition in addition to the water efficiency,

Figure 8: The "Agro-technical methods" branch (level 1 only)

"Runoff" means the total design facilities to direct rainwater runoff through the site in order to give vegetation an additional water supply (Figure 9).

Figure 9: The "Runoff" branch (level 1 only)

Figure 5: The "Landscape Design" branch (level 2 only)

The "Non-potable Water" is a branch of strategies that reduce potable water demands for irrigation by using "Captured Rainwater", "Recycled Graywater" or "Treated Wastewater" (Figure 10).

The "Irrigation" branch includes the "High Efficiency Irrigation strategies" and the "Plan of Action" for efficient and effective operation like "Watering Schedules", "Watering Duration" and "Irrigation Calculations" (Figure 6). The irrigation calculations will be discussed in detail in chapter 4.

Figure 10: The "Runoff" branch (level 1 only) Figure 6: The "Irrigation" branch (level 1 only)

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These two last subjects, among the other things, maximize the use of on-site natural resources and meet irrigation demand in the most sustainable manner [6]. There are almost 80 different patterns in the tool, which are embedded within each other in a semilattice order, during the decision-making process. 3.2. The pattern format All patterns have the same format and interface. They consist of a title, a definition and a list of recommendations for successful implementation in the garden. For example see the Landscape Design Pattern (Figure 11). The pattern has also an information part which, if necessary, continues on to a second page (Figure 12).

Figure 11: The "Landscape Design-Recommendations" pattern page

Figure 12: The "Landscape Design-Information" pattern page

Within the text there are highlighted words which are actually new patterns embedded within the "Landscape Design" pattern, similar to common web navigation. Each pattern choice leads us to a new pattern page, and in this way, we create the semilattice pattern of our decision making process as mentioned earlier. Every page has also a hierarchical navigation as indicated on the right. The information part includes quantitative data, which is highlighted and there are also references to

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relevant external links like governmental sites or case studies.

4. THE QUANTITATIVE TOOL The necessity for evaluating the conservation rate of water irrigation in the designated garden is obvious. Hence, the KBCAD tool for water efficient gardens has a quantitative part that includes a calculator to supports the qualitative design process. There are series of questions, which are required to be answered. The fill in data refer to the different types of plants in the proposed garden and their distribution in square meter units. The climate conditions are a major subject that is taken into account in the calculations: First by considering the local climate, the orientation of the plants in the garden and the topography of the site. Secondly, enumerate the microclimate factors which the proposed design has produced to enable the reduction of irrigation's demands due to minimizing evapotranspiration. In other words, the design should promote the comfort of the plants in the garden through maximizing shading on soil and plants and minimizing unwanted winds. These places in gardens can be for example vegetation area located in courtyards, north sides of slopes, north side of buildings and areas under wide building overhangs [6]. The results are a display of calculations determining the amounts of water needed for the garden irrigation: schedules and durations annually and monthly (Table 1). Table 1: Calculated as-designed annual and monthly water consumption

The evapotranspiration column up in table 1 reflects the weighted data, which takes into account the microclimate factors as aforementioned. There is also an output concerning the percentage of water reduction that can be gained by the proposed design. This data is an outcome of a comparison between the calculated as-designed water use rate and a calculated baseline water use rate for the same climatic area (Table 2). Table 2: The water reduction rate

The on-spot quantitative examination exposes the designer to elements in his design that

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

consumed a large amount of water. Hence he may wish to consider improvements in his design in order to gain a greater reduction in garden water consumption. In this way, a comprehensive design is formed, characterized by a qualitative decisionmaking process and a quantitative evaluation of it simultaneously.

5. THE GARDEN CASE-STUDY In order to experience the design tool in action, the garden of the author family that is located in Alon-Hagalil, a place near Nazareth, was selected as a case study. This place has a Mediterranean climate with an annual average of 570 mm of rain. Particularly problematic is the fact that precipitation occurs only three to four months of the year, which means that there is a long period of eight to nine months of the year that irrigation of the garden is necessary. This existing garden was explored comprehensively both qualitatively and quantitatively. An upgrading process of implementation of the pattern language design tool in the garden has been carried out, as well as the quantitative tool. The sequence of patterns, and recommendations that have been exploited within the process, were documented. A quantitative evaluation analyzed the alteration in the amounts of water consumption during the period of the research (three summers in total). 5.1. Results The analyzed quantitative evaluation of the design alternative that was selected according to the recommendations of the KBCAD tool shows a reduction of 60% in water consumption for garden irrigation. This calculated numbers actually reflect the results on site, according to the bill obtained from the utility. This number presents the potential of reduction in water consumption for irrigation. Figure 13 presents the actual water consumption during the years 2007 (the garden before the retrofit) and during the year 2010 (after retrofitting). The retrofit of the garden over these three years managed to reduce the outdoor water consumption by 53% and the total water consumption by 43%. In 2007 the outdoor water consumption stood at 45% and in 2010 it was only 36% of total domestic water consumption.

Figure 13: 2007 & 2010 Domestic Water Consumption (%) of the garden case study

5.2. The Sequence of Patterns used in the retrofit The sequence of patterns that were chosen in order to achieve water efficient garden Includes:

 Appraising the existing garden to see if it well adapted to the "Climate" and "Orientation" of the garden.  Changing several plants in order to take advantage of the "Microclimate" factors and to minimize the "Evapotranspiration". For instance: increasing the shaded areas in the garden with "Trees" and "Groundcover".  Reevaluating the "Combination of Plants" in accordance with the intended purposes of the garden. This gave rise to the minimization of "Lawn" area and "Annual Flowers", which in the retrofit garden were planted in planters and located in centered spots in the garden.  In search of adjustments in some garden-beds choices made here actually lead us to the new tree: "Vegetation "which directs the selection of climate-tolerant plants, specific for each garden's climate conditions.  The Pattern of "Water Efficient Plants", taught us there are a variety of planted forms of this kind: tree, shrub and grass for selection according to the situation. From this point in time and on, every plant was chosen intently to enable easy adaption to the site, a practice which wasn't exactly considered previously.  By considering "Built Elements", like "Pavement" and "Pergola" we assured the proper recommendations are maintained. Through the semi lattice pattern a new branch of the tree: “Runoff” was selected, as well as: “catchment area”, “slopes” and ”permeability”. These patterns are essential to consider when determining paving for the garden. Strategies concerning "Non-potable Water" were not implied, as it is not yet allowed by the Israeli Health Authority to be used in private gardens.  However, the branch of "Irrigation" was very significant in achieving the required goal. In this branch number of efficient irrigation practice were applied in the garden, like: Verification of "Irrigation Schedules" and "Duration" on a monthly basis, that yielded effective results. It became evident that the garden was irrigated with permanent amounts of water each time without adjusting it to the seasonal climate and precipitation changes. Therefore, there was a situation of surplus irrigation and certainly not efficient. “Agro-technical Methods" is another important subject, which involve techniques of amending the soil, like "Mulching", "Mowing", "Fertilization", "Weeding" and "Cultivating" for the health of the plants and for the emendation of the water's absorption in the soil. The decision-making process of this case-study has implemented 38 patterns out of 80 and approximately 100 recommendations (Figure 14). Naturally, in the design process of every garden, a unique sequence of patterns will be chosen. It is a matter of climatic and environmental conditions of the place, budget limitations, personal demands and priorities etc.

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Figure 14: Patterns used in the case-study

6. SUMMERY AND CONCLUSIONS This paper presented a KBCAD tool for the design of water efficient gardens that is based on the "Pattern Language". Special emphasis was put on the climatic adjustment in the design of the garden in a similar way to the bio-climatic design of buildings: considering the solar radiation, wind and "Orientation", in order to maximize the "Microclimate" conditions of the garden, and to minimize the "Evapotranspiration" from the plants and "Soil". This tool includes qualitative part, presented by eighty patterns, and a quantitative part presented by an excel sheet, where all parameters to be considered and the formulas are presented. The qualitative and the quantitative sections work together as one matching software and enable a quantitative examination during and after the design process. Gardens, as can be deduced, are holistic dynamic systems that never stand still. It is essential to recognize that gardens require evolution and not revolution in design and maintenance. As a pattern language tool it is particularly supporting this kind of conception of design, and makes the process gradual, flexible and uniquely adjusted to every project. Practically, the decision-making process of the KBCAD tool can be performed over and over again because gardens are systems that are constantly undergoing change with altering needs. There must be a permanent operation of maintenance and improvements in the garden according to the dynamic situation of it, in order to obtain the water efficiency in the garden. The easiness in using this tool and the performance obtained by applying it was presented by a case study that showed that about 60% in water consumption for garden irrigation could be achieved.

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This calculated number was compared with the actually results on site, based on current utility bill. This number presents the potential of reduction in water consumption for irrigation by appropriate design of gardens.

7. REFERENCE [1] Be'eri, S. (2004), Water Saving in the Israeli Urban Sector. A Comprehensive Feasibility Study. MSc, Technion-Israel institute of Technology. [2] U.S Environmental Protection Agency (2010). "How We Use Water in These United States". Esa21 [Online] January 2004 http://esa21. kennesaw.edu/activities/water-use/water-useoverview-epa.pdf [Accessed 7 April 2010]. [3] Domene, E. & Sauri, D. (2006). "Urbanisation and Water Consumption: Influencing Factors in the Metropolitan Region of Barcelona". Urban Studies [Online] August 43, (9): 1605-1623. http://usj.sagepub.com/citmgr?gca=spusj;43/9/16 05 [Accessed 7 April 2010]. [4] Alexander, C., Ishikawa, S. & Silverstein, M. (1977). A Pattern Language: Towns, Buildings, Construction. New York: Oxford University Press. [5] Mazria, E. (1979). The Passive Solar Energy Book. Emmaus: Rodale Press. [6] USGBC-LEED, US Green Building Council (2007) New Construction & Major Renovation rd edition: Water V2.2, Reference Guide, 3 Efficiency, p. 117-127. Washington DC: USGBC. [7] Pattern Language (2001) "Methods" Pattern Language [Online]. http:// www. Patternlanguage. com/leveltwo/methods.htm [Accessed 1 November 2009].

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Urban River Microclimates Abigail HATHWAY1, Steve SHARPLES 2 1

Department of Civil and Structural Engineering, University of Sheffield, Sheffield, UK 2 School of Architecture, University of Liverpool, Liverpool, UK

ABSTRACT: The effect of the urban area on increasing air temperatures is well recognised and has been th documented since the early 19 Century. The replacement of the natural landscape with hard materials, the ejection of heat from urban processes and large height to width ratios trapping radiative energy all combine to increase the temperature in urban areas. With the increased likelihood of hotter summers this can have severe impacts on human health due to both direct heat related illnesses, but also due to air pollution from increased levels of ozone in the lower atmosphere. This study will focus on the effect of urban design on the local microclimate in the UK, with a particular focus on urban rivers. The study is based on microclimate data collected during the summer months in the UK city of Sheffield. Three different types of urban form are considered, and temperature and humidity data collected at each are presented. During the day time the river is found to be cooler than the surrounding landscape, and some variation was found dependent on the urban form. Keywords: river corridors, urban microclimate, urban heat island

1. INTRODUCTION Urbanisation has been recognised to generate increased local temperatures for nearly 200 years [1]. Anthroprogenic heat generation is a key factor, however so is the design of the urban landscape. The replacement of natural landscapes with hard impervious materials absorbs long wave radiation during the day, providing heat storage and slowly releasing this into the locality at night. This is further compounded by ‘street canyons’ trapping the heat and reducing night cooling [2-4]. The reimplementation of natural landscapes into our cities is therefore of great interest in order to provide resilience to climate change. To this end much work has been carried out to understand the impact of urban greenery of various types to reduce the impact of the Urban Heat Island (UHI). Research has found that large parks provide cooling that is able to penetrate to approximately its own width into the city [6] and trees are well known to provide cooling through both shading and evapotranspiration (e.g.[7]). The increase in impervious surfacing due to urbanisation is a significant contributor to the UHI effect. As water is directed to sewers, and removed rapidly from the ground surface, the capacity for cooling due to latent heat flux is reduced. Ponds, lakes and rivers therefore have the potential to replace this moisture in the urban environment. Water bodies are often cited as providing the potential for cooling due to evaporation, both traditionally (e.g. Islamic Architecture) and equally in the modern day when fountains are sold as cooling devices [8], although quantification of the cooling effect is somewhat limited. The presence of lakes and rivers may therefore propagate cooling into the urban environment, in a similar way to the cooling provided by parks and green areas. To date research on the impact of rivers on the local microclimate has been mainly carried out in Japan [9] and Korea [10]. Both demonstrated cooler temperatures directly

above the river, with some penetration into the city. Kim [10] made use of a large daylighting project to evaluate the effect the river had on the local climate and found small reductions in temperature following the river being opened up.

2. URBAN RIVER CORRIDORS In comparison to static parks and lakes, rivers provide a different cooling process; flowing in from outside the city their temperature is dependent on processes occurring upstream. River temperatures may be impacted by the surrounding surfaces, stormwater run off, or releases of water from cooling processes for buildings or industry. Considering the sensible heat flux alone, large bodies of water will remain a stable temperature within the urban environment absorbing heat from the air during hot weather due to their high specific heat capacity. Equally storm events will often re-cool rivers, recharging their potential to act as a cool oasis. Alongside sensible cooling from the lower temperature river, the presence of water will enable latent cooling. This provides an important opportunity for reducing the UHI, as one of the key factors in its development is thought to be the change in ratio of sensible and latent heat flux [5]. Although introducing a river into a city is unlikely to be a design choice in urban planning for climate change there is increased interest in opening up culverted water courses. In the UK the Chartered Institute for Water and Environment Management is promoting the daylighting of watercourses citing reasons such as improvements in ecological value and reduction in flood risk [11]. Furthermore where a river is present the design of the immediate surroundings may impact the magnitude any cooling effect has on the entire urban area. In order to create sustainable living environments the design of a river front requires the consideration of a wide variety of factors. URSULA (Urban River Corridors and Sustainable Living agendas) is an

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interdisciplinary project which aims to consider the social, economic and environmental gains to be made by integrated and innovative interventions in urban river corridors. This covers research into the ecology of urban rivers, the implementation of sustainable drainage systems, engagement with stakeholders in urban design, access improvements to the river, economic value, and the use of computer visualisations, as well as urban design for an improved microclimate. These aspects will be brought together at one site on an urban river to understand how regeneration may be carried out to provide multiple benefits. Even considering purely the microclimate implications there are many, sometimes competing, factors that need to be considered. Shading and orientation to prevailing wind directions have significant impacts on resulting temperatures. Equally an increase in temperature in summer can mean an increase in temperature in winter, and a resulting reduction in energy required for heating. Although shading may reduce overheating it will reduce available daylight. Designs which increase airflow, removing heat and pollutants, may result in high and uncomfortable windspeeds during certain seasons. There is a large proportion of literature available providing guidance for designing to improve the local microclimate. A few examples include recommendations for height-width ratios of streets be between 0.4 and 0.65 [12] the provision of street trees with tall trunks and large canopies [13], and the placement of small 0.1ha parks every 200m [14]. There is also substantial literature discussing the use of reflective materials [5]. This study presents the preliminary analysis of microclimate data collected on a river corridor in the vicinity of a variety of urban forms. The aim of the study is to understand how variation in urban form on a river corridor can promote any benefits the river provides in the mitigation of the UHI effect.

solar radiation shields were installed in three distinctly different locations. The manufacturers stated accuracy of the ibuttons is +/- 0.5°C, however a series of calibrations every 4 months found them to measure to within 0.3°C of each other. Figure 2 shows sketches indicating the three types of urban form considered. Monitors 1-5 were mounted at a height of 3m attached to a pedestrian walkway. Monitors 6-12 were mounted between 1.2 and 1.5m above ground level. Monitors 3,5,8,9, and 10 were attached adjacent to car parks, and monitor 11 was adjacent to a minor road. The remainder were located in pedestrian areas. N

a)

b)

3. METHODOLOGY The study is located along the river Don as it travels through the city of Sheffield in the UK. The river originates in the Pennines and passes through mainly rural locations before reaching the outskirts of the city. The city has been shown to have a UHI of 2°C on a spring day [15]. The study site borders the north of the city centre, and extends approximately 150m either side of the inner ring road. A reference urban weather station is set up 1.5km from the river, on the inside of the ring road and approximately 25m higher than the riverside locations. The temperatures measured at this location are increased by 0.24°C in the results to account for the altitude difference [15]. This reference weather station is located at roof level and monitors temperature (°C), humidity (%), wind 2 speed (m/s) and direction (°) and light levels (W/m ). At the study site a weather station is located at a height of 1.5m adjacent to the river to measure the microclimatic conditions along the river which includes temperature, humidity, wind speed, direction and water temperature. Twelve temperature and humidity monitors (iButtons, Maxim, USA), housed in

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c) Figure 1: Sketches showing three types of urban form considered a) Open square, b) Narrow Streets and c) Enclosed. Not to scale.

In the open square the buildings are approximately 6 storeys to the north and south, and 10 storeys to the west. At the narrow streets site the buildings are much smaller scale being only 2 storeys high; the ‘streets’ are pedestrian walkways

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

<10m wide. At the enclosed site there is a pedestrian path between the river and the building which is 7 storeys high. Temperature data has been collected for an entire year at 20minute intervals. However preliminary analysis showed different effects due to the ambient air temperature, therefore only the summer months will be considered for the analysis st presented here. This includes data from the 1 May th to 12 August. Monitors 11 and 12 were only in th operation from the 18 June. Analysis was carried out comparing temperatures at each location (Ti) in reference to the urban weather station (Turban). The difference between the sites was based on three hour averages. Since impact of wind and solar gain would have differed at each site Pearson’s correlation analysis was carried out to identify if temperature differences between sites were correlated with changes in light levels or wind speeds. Where this is deemed significant to interpreting the results the correlations are presented below. The notation r is the Pearson’s correlation coefficient with +1 equalling a perfect positive correlation and -1 a perfect negative correlation. The statistical significance of this is represented by P, where p<0.05 is taken as being statistically significant. The number of independent measurements used in the analysis is represented by N. The results are presented for day and night time separately, where day time is classed as 06:0021:00, and night time 21:00- 06:00. In order to identify the capacity for sensible cooling from the river the temperature variation of the water was analysed and consideration given to a week long period during the summer when air temperatures approached 25°C on five adjacent days.

magnitude of temperature difference due to the presence of the river alone.

Figure 2:Variation in urban reference air temperature (thick black line) and water temperature (dotted grey line) over 7 days. Lowest line shows difference in temperature between urban station and monitor 6.

4.2. Open Squares The temperature difference at each location is calculated using Turban-Ti, therefore a positive value represents the magnitude of cooling in comparison to the urban weather station.

4. RESULTS 4.1. Water Temperature The river has the capacity to provide cooling due to both sensible and latent heat flux. The former is directly related to the temperature of the river. The water temperature of the river, measured at the base of the channel adjacent to the bank, varied between 2.7 and 17.8°C, whereas the air temperature immediately at the bank in the same location varied between -3.9 and 29.0°C. Figure 2 presents a period when temperatures approached or exceeded 25°C on 5 days in a row. The steady increase in river temperature can be seen over the period of hot weather but with much smaller variation than the air temperature. During this time the difference between the air temperatures in the city, and directly adjacent to the river rises to nearly 5°C. The greatest difference in temperature occurs first thing in the morning around 7-9am. It should be noted that the riverside could be up to 2°C warmer than the urban weather monitoring at around 8pm. The correlation between this temperature difference and the light levels over the city is significant (r=0.538, p<0.01, N=781) for the summer period. Further work is required to identify the

Figure 3: Average difference between urban and site temperature measurements. Dotted lines show night time differences, solid line day time differences. The error bars represent the standard deviation.

Figure 3 presents the average cooling in the urban square adjacent to the river, with temperature monitors spanning from one directly adjacent to the river on the east, to monitor 10, 60m away from the west bank as shown in figure 1a. There is a clear decrease in temperature at the centre of the river (measured from the side of a footbridge), with an average difference at the centre of the river 1°C cooler than the urban location during the day time. During hot weather this difference can be seen to increase substantially to nearly 5°C (see Figure 2).

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The cooling decreases rapidly with distance from the river to be within the limits of temperature detection. At the furthest point from the river there is an increase in cooling. This logger is located near to an opening aligned to the prevailing wind, and is shaded for the majority of the day. However correlations with temperature difference between this logger and the centre of the river (T10-T6) showed little correlation to either sunshine or wind speed (r=0.2; P<0.05, N=781 and r=-0.02, P<0.50, N=781 respectively). At night the difference alters and the riverside locations show increased temperatures in comparison to the urban reference. This warming though has a lower magnitude than the cooling provided during the day and approaches the limits of the monitoring equipment.

similar, approximately 0.5°C cooler than the urban reference location during the day and 0.5°C warmer at night. Within the streets at positions 2 and 4 there is a large difference. However, the south east facing wall behind monitor 4 is less shaded than at position 2. A correlation between the temperature difference between monitors 2 and 4, and the light levels in 2 W/m over the city found this temperature difference has a significant positive correlation to the light levels (r=0.82, p<0.01, N=781).

4.3. Variation in riverside temperatures The variation in temperature parallel to the river was analysed in order to understand how the building’s form adjacent to the river impacts on any cooling effect. Temperatures measured at monitors 1,6,7,11 and 12 shown in Figure 1 were used in comparison. As before the average daytime and night-time differences from the urban reference location are taken and plotted along with the standard deviation in Figure 4. Similar to above the riverside locations are cooler during the day time and warmer at night. Monitor 11 which is located on the opposite of the river to the open square is the warmest position during both the day and the night. This monitor is located closest to a road. Monitor 1 which is located at an opening to a linear street orientated approximately in the prevailing wind direction is the coolest location, this is also the location furthest from the urban centre, approximately 300m upstream from the open square site.

Figure 5: Magnitude of cooling along street open to the river including temperature measured at river centre. Dotted line shows the night time differences and the solid line the day time differences. The error bars represent the standard deviation.

Figure 6: Magnitude of cooling along street closed to the river including temperature measured at river centre and riverside. Dotted line shows the night time differences and the solid line the day time differences. The error bars represent the standard deviation.

Figure 4: Cooling magnitude at locations adjacent to river with different urban forms. Dotted line shows the night time differences, and the solid line the day time differences. The error bars represent the standard deviation.

4.4. Narrow Streets The ‘narrow streets’ site gives the opportunity to consider two different scenarios, with an opening to the river, and a street with no opening (see Figure 1b). Figures 5 and 6 show the temperature variation along both streets from the riverside, till the opening into the car park. As can be seen at the ends of the streets (monitors 3 and 5) the temperatures are very

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Monitors 3,5 and 9 are all located approximately 30m from the riverside. Although they are based in different locations, considering the average data for the summer period they all show similar differences to the urban temperatures being 0.5°C cooler in the daytime and 0.5°C warmer at night.

5. CONCLUSION This study provides preliminary analysis of microclimate data collected along an urban river corridor. The results showed cooler temperatures immediately above the river compared to the banks of the river. A daytime average reduction in temperature of 1°C compared to the urban

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

environment was found during the summer months. During night-time the river was found to be warmer than the urban reference. Variation in air temperature was found depending on the urban form adjacent to the river, with the coolest location being at a narrow street aligned to approximately the prevailing wind. However this site was also the furthest from the city centre. Two adjacent streets, open and closed to the river had very similar temperatures at the far end where they connected to the same space. Thirty metres from the river the temperature difference to the urban location was similar despite differences in urban form. Further work is required to assess the variation in temperature across the entire year, and to incorporate the effect of solar radiation and wind speed into the analysis. Furthermore the interdependency between water temperature and air temperature requires consideration. The work presented above provided a highly simplistic method of differentiating between day and night. Considering the Urban Heat Island effect has its most profound effect during the night analysis of the transient variation over the diurnal period is required to understand how the difference in temperature between the river and the urban area varies through time.

6. ACKNOWLEDGEMENTS This paper is based on work undertaken as part of the URSULA project funded by the Engineering and Physical Sciences Research Council (grant number EP/F007388/1). The authors are grateful for EPSRC's support. The views presented in the paper are those of the authors, and cannot be taken as indicative in any way of the position of URSULA colleagues, partners or of EPSRC. All errors are those of the authors alone.

7. REFERENCES [1] Howard, L (1833) The Climate of London. London: Harvey and Darton. [2] Stone, B. and Rodgers M.O (2001) Urban Form and Thermal Efficiency: How the Design of Cities influence the urban heat island effect. Journal of American Planning Association, 67(2). 186-198. [3] Coutts, A.M., Beringer J., and Tapper N.J (2007). Impact of Increasing Urban Density on Local Climate: Spatial and Temporal Variations in Surface Energy Balance in Melbourne, Australia. Journal of Applied Meteorology and Climatology, 2007. 46: 477-493. [4] Grimmond, C.S.B. and Oke T.R (1999) Heat storage in urban areas: Local-scale observations and evaluation of a simple model. Journal of Applied Meteorology, 38: 922-940.

[5] Smith, C. and Levermore G. (2008) Designing urban spaces and buildings to improve sustainability and quality of life in a warmer world. Energy Policy, 36: 4558-4562. [6] Jauregui, E (1990) Influence of a large urban park on temperature and convective precipitation in a tropical city. Energy and Buildings, 15: 457-463 [7] Giridharan, R., et al. (2008) Lowering the outdoor temperature in high-rise high-density residential developments of coastal Hong Kong: The vegetation influence. Building and Environment, 43(10): 1583-1595 [8] Nishimura, N., et al. (1998) Novel Water Facilities for creation of comfortable urban micrometeorology. Solar Energy, 64(4-6): 197207 [9] Murakawa, S., Sekine T., and Narita K. (1990) Study of the Effects of a River on the Thermal Environment in an Urban Area. Energy and Buildings, 15-16: p. 993-1001. [10] Kim, Y.H., et al. (2008) Does the restoration of an inner-city stream in Seoul affect local thermal environment. Theoretical Applied Climatology, 92: p. 239-248 [11] CIWEM, (2007) Policy Position Statement on Deculverting of Water-courses. Chartered Institute of Water and Environmental Management: London. [12] Oke, T.R. (1988) Street Design and Urban Canopy Layer Climate. Energy and Buildings, 11: p. 103-113. [13] Yang, F., Lau, S.S.Y. and Qian, F. (2010) Summer time heat island intensities in three high rise housing quarters in inner city Shanghai, China. Building and Environment, 45(1): p. 115134. [14] Shashua-Bar, L. and Hoffman, M.E (2000) Vegetation as a climatic component in the design of an urban street: An emperical model for predicting the cooling effect of urban green areas with trees. Energy and Buildings, 31(3): p. 221-235. [15] Lee, S.E. and Sharples S. (2008) An Analysis of the Urban Heat Island of Sheffield - the impact of a changing climate., in 25th Conference on Passive and Low Energy Architecture. 2008: Dublin.

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  th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 

                                                                  

                                                                                                                                                      

 

                                                         

                                                          

CLIMATIC, WATER AND BIODIVERSITY CONTEXT

189



PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                                                

  

       

                                           

 

                     





   

        



190



CLIMATIC, WATER AND BIODIVERSITY CONTEXT

   



PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

 

  



  



 





 

  



 



 

                  





                           













  



            



CLIMATIC, WATER AND BIODIVERSITY CONTEXT



191



PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                                              



         

                                                                   

                   



  

                     



192



CLIMATIC, WATER AND BIODIVERSITY CONTEXT

 





PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                                               

                     

            

            

           

 

     

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    

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                           



CLIMATIC, WATER AND BIODIVERSITY CONTEXT

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

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                                                                                                                                                

                                                                                                                                                                          

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CLIMATIC, WATER AND BIODIVERSITY CONTEXT

                                                                                                                                                                                                                      

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Microclimate in Urban Forest Fragments CRISTIANE DACANAL1, LUCILA CHEBEL LABAKI1 1

School of Civil Engineering, Architecture and Urban Planning, University of Campinas, Campinas, Brazil

ABSTRACT: Urban forest fragments play an important role in urban climate. The foliage of plants intercepts solar radiation, diminishing heat gain above canopy layer; air humidity is increased by transpiration process. This specific microclimate in green areas depends on foliage density, diversity and type of species and canopy stratification. Sky View Factor (SVF) represents physical structure of vegetation and it can be related with the microclimate. Six urban forest fragments are selected in Campinas, Sao Paulo (Brazil). Air temperature and air humidity were monitored in 60 points during the year of 2009. In addition, hemispherical photographs were used to calculate SVF in the Gap Light Analyzer software. This index was compared to microclimate data. Results demonstrate that minimum air temperature and daily thermal amplitude augment with open canopy. Little green areas are more susceptible to urban microclimate influences. They presented elevated SVF, low relative air humidity and elevated minimum air temperature. The homogeneity of forestry structure associated with low open canopy could indicate thermal stability, serving as parameter to forestry management. Keywords: microclimate, sky view factor, urban forestry, urban planning

  1. INTRODUCTION The green urban areas, such as squares, parks and forests perform a socio-environmental role, as they attract people to recreation, sports and rest and also bring benefits to the environment. These areas, when vegetated, are the habitat for wildlife, intercept the rain that slowly permeates the soil, which prevents runoff and flooding, improve air quality retaining pollutant particles, and modify the urban microclimate [1]. In tropical regions, the microclimate of urban forests aside from providing thermal comfort [2] works on the nearby buildings, which may be more efficient from the energy standpoint. In Brazil, the researches on the microclimate of isolated or grouped trees as well as researches on thermal comfort in opens spaces have been developed in recent years [3]. However, little is know about urban forest fragments, which are characterized by dense, stratified and diverse vegetation. Overall, the researches on forests fragments focus on the management and conservation of areas located outside the urban perimeter [4]-[5]-[6]. How would the microclimate of urban forest fragments with high leaf density be? Would there be a relation between the physical characteristics of the forest canopy and the resulting microclimate? Can the influence of urban climate on the microclimate of the fragments be identified? 1.1. Vegetation an microclimate The plants, seen as a living organism, absorb and emit radiation, perspire and exchange heat with the atmosphere. The leaves and flowers orient themselves in relation to the incident radiation, the stomata open or close themselves according to the availability of radiation and water and physical and

biochemical mechanisms occur so that their energy balance is efficient. Part of the incident solar radiation is absorbed during the photosynthetic process, and another fraction is transmitted and reflected. In composition of plants, with several strata (trees, shrubs, grass, vine), the radiation is used by the highest crowns to the lowest foliage, so that the radiation that reaches the ground is only 2% [7]. The more varied in species, the greater the capacity to absorb radiation. Comparing the radiation spectrum under a shrub fence to a dense forest, one can observe that the range between 400 ηm and 700 ηm is virtually all absorbed by the forest, while in the shrubs this range is focused around 700 ηm [7]. The water percolated in the soil is absorbed by the roots, occurring the transpiration from the leaves and the evaporation from the soil. The larger the leaf area, the larger the transpiration, as long as there is water availability. The leaves gain heat and lose heat through ventilation, which accelerates the transpiration process and the convective exchanges. Hence, the greater the wind speed, the greater the heat and humidity loss from the plants to the air. The resulting microclimate in the height of the tree trunks is characterized by the shading, low temperature and high humidity, considering that the daily temperature range is lower than in open fields. The night warming occurs due to the barrier formed by the vegetation foliage in relation to the heat loss from the soil to the atmosphere. Next to green wooded areas the air temperature decreases and the air humidity increases, winds are displaced and their speed is reduced, the solar radiation is attenuated by the vegetation foliage. The result is a microclimate next to the maritime, modifying the urban climate usually more arid and hot [8].

CLIMATIC, WATER AND BIODIVERSITY CONTEXT

195

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

1.2. Sky y view factor and a vegetatio on The hemispheric h photographs arre used to de epict the structture of the forrest canopy, from f the open ning measuress (Sky View Factor - SVF), the leaf area and leaf angle e. On the othe er hand, the ca anopy structurre is related to o environmen ntal factors which may pla ay a physiolog gical role in th he life of the forest f individu uals, as the flo ow of direct and diffuse ligh ht which reacches the soil or o the quantityy of solar radiiation intercep pted by the foliage [9]. c be a pa arameter for the Thus, the SVF can evaluation of the micro oclimate and its implication n for n status [10]. the forestt conservation The software s Gap p Light Analyser (GLA v.2), v developed by Frazer et e al (1999) in n Canada, allo ows the inserrtion of hemispheric phottographs for the calculatio on on canop py opening, considering the adjustment of the proje ection accordiing to the type e of lens used d in the camerra [9].

2. OBJ JECTIVE This work, developed in the city c of Campinas (Latitude 22 48 57 Sou uth, Longitude e 47 03 33 West, W 640m), São Paulo state e (Brazil), aim ms to characterize the physiical structure of the canopyy of urban forest fragmentss, from hemisspheric photographs and frrom the calcu ulation of the Sky View Fa actor (SVF), and relate thiss index to the microclimate.

Saint Josep ph Woods

Italian Wo oods

Guarantãs Woods

German Woods W

ods Peace Woo

Figurre 1: Location o of study areas

3.2 2. Microclima ate monitorin ng

3. MET THODOLOGY 3.1. Pres sentation of the t study are eas The six s urban forrest fragmentts studied he ere, originally belonge to se easonal semi deciduous forrest, which occcurs in clim mates with tw wo well defined seasons – summer wiith heavy rain n followed by dry winters, a period when n the whole fo orest loses so ome of its leavves [11]. The forest f fragmen nts have tree es, shrubs, grrass and vine stratum, with h the except of Saint Geneve w is a con nservation un nit [12]. All arreas Forest, which suffer antthropic pressu ure, are underr the influence e of the urba an climate and a have no possibility of connectin ng to other gre een areas. The areas a vary in n dimensionss (Table 1), are located in different re egions of the city (Figure 1), n predominan ntly residentia al neighborho ood. always in They are used for walkking, friends gathering, g job and leisure [2]. Table 1: Forest F fragmentts studied in Ca ampinas

196

Saint Gen neve Grove

Code

Local

Area (ha)

SGG

Saint Geneve Grovve

252.7 70

ITA

Ita alian Woods

1.40 0

GER

Gerrman Woods

2.00 0

S.JOS S

Saint Joseph Wood ds

3.36 6

GUA

Guarantãs Woodss

4.38 8

PEA

Pe eace Woods

6.29 9

CLIMATIC, WATER AND BIODIVERSITY CONTEXT

Between January J and d August 2009 2 air tem mperature, air a relative humidity an nd globe tem mperature we ere monitored d in points within w the forest fragmentss, alternating measuremen nts among the e study areass. The acquissitions were performed onlly during the day, d between 09:00am and 06:00pm, app proximately. There T were alsso continuous monitoring

of temperature and relative humidity in a sim multaneous he study areass, making it possible p to poiint between th com mpare them. Testo data-lo oggers, models 175-T2

and d 177-H1, were placed in n tripods 1.5 5m height, acq quisitions tookk place hourly. 3.3 3. Hemispheric photogra aphs and sky s view factor

The hemisph heric photogra aphs were tak ken in July 200 09, in the ea arly phase of semi deciduo ous forest fragments. It is worth w noting tthat this year the winter wa as wet, delayin ng the fall of le eaves. A Nixon Co oolpix 5000 ((digital camerra) and a con nverter lens fo or fisheye Nikkkor FC-E8 were w used. The camera wass connected tto a tripod, lev veled by a bub bble level, witth the lens faccing the sky. By B using a com mpass the top p of the camerra was directe ed towards the e North. The im mages were ttaken at 1.5m height, in mu uch the same way w as the miicroclimate mo onitoring. The bitmapp ped images w were inserted into GLA v.2 2. The polar projection was used and the adjjustment of magnetic m north was made. The T colors we ere transform med into wh hite (Sky) and a black (ob bstructions) to calculate the canopy openn ness.

PLEA2011 - 27th International conference e on Passive an nd Low Energy Architecture, A Lo ouvain-la-Neuve e, Belgium, 13-1 15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

4. RES SULTS 4.1. Microclimate of study s areas The maximum m air temperature t a average had little l variation between the areas (0.6oC), while the emperature avverage was more m variation of minimum te nt (2.2oC) (Tab ble 2). On the e other hand, the significan relative air a humidity was more elevated in la arge green areas (SGG ca ase) and in the presence e of ase). The sm maller amplitudes watercourse (PEA ca h watercourses (PEA and GUA G occurred in places with cases).

13.70% (standa ard deviation 3.92). In Figu ure 2 it is pos ssible to com mpare forest ccanopy to SV VF varying from 6.97 and 21.06%. T The lowest percentage p ind dicates the pre esence of inte erlaced trees with large lea af area, while e the high percentage of o canopy ope enness indica ates areas witth glades, tha at is, there is a greater disstance betwee en individual trees and und derstory of little significance e.

Table 2: Hygrotermal behavior of the urban fo orest fragments.. Simultaneous monitoring betw ween Jan. and Ago. A 2009 (totall of 40 days),

SGG

Tmax o ( C) 26.0

Tmin m (oC) 16 6.8

ΔT o ( C) 9.2

URmax (%) 98.5

UR Rmin (% %) 66 6.1

ITA

26.4

19 9.0

7.5

86.6

56 6.1

Local

GER

26.6

18 8.8

7.8

92.2

58 8.0

S.JOS

26.4

18 8.7

7.7

90.7

58 8.4

GUA

26.3

18 8.4

7.8

88.7

58 8.8

PEA

26.1

17 7.8

8.3

92.9

66 6.0

Label - Tmax – Average e maximum te emperature; Tmin m – Average minimum m temperature; ΔT – daily tempera ature range; UR Rmax - Average maximum m relativve humidity; UR Rmín – Average minimum m relative e humidity.

There e was a clo ose correlatio on between the increase in daily temp perature ranges (ΔT) and the 2 size of green areas (rr = 0.83). It may indicate not only the e influence of urban climate of forest fragmentss warming the e green areas during the da ays, but also the t potential for nighttime cooling, which is higher in the larger areas. a Howevver, other facttors may indiccate the differrences in tem mperature rang ges, such as the presence of o water, the conservation c le evel of the are eas and the distance d to the e monitored point in relation n to the urban frontier (stree et). The comparison c off the areas ind dicates that SGG S is less warm w and morre humid. On the other ha and, ITA Wood ds, which hass the smaller dimension d and is not close e to valley botttoms, is the warmer and less l humid are ea. 4.2. Can nopy opennes ss and microclimate The photographs and microclimate monitoring en in: SGG – 2 points; ITA – 7 points; GER G were take – 8 pointss; S.JOS – 12 2 points; GUA – 11 points; PEA P – 10 po oints, totalizin ng 50 points. An initial test showed lo ow correlation n between SVF F and the clim mate variationss of these 50 0 points. This is due to the variation of physical structure of the forest fragme ents es, as noted in the previous and theirr microclimate item. Therefore it was w opted forr the descrip ptive o the six area as during the time t of maxim mum analysis of air tempe erature occurre ence (02:00pm m), since the time t of minim mum temperrature occurrrence was not monitored d. The sky s view facto or (the averag ge of the points) from eacch study area varied betwe een 10.94% and 15.98%. The overall average a of the 50 points was w

SVF = 6..97%

SVF=21.06% %

Fig gure 2: Hemisph heric photograp phs of the canop py of urban forest fragments and corressponding view fa actor.

The smaller canopy openn ness occurred d in S.JOS (av verage SVF 10.94%), 1 even n when comp paring the ma aximum (13.3% %) and minimu um (6.97%) va alue to the oth her locationss. The diffe erence betw ween the ma aximum and minimum m SVF in this area was w 6.33%. The wider open ning occurred in ITA (average SVF between the points of 15.98%), with a variation b ma aximum and minimum op pening of 8.0 05%. This varriation in the e forest cano opy opening was the gre eater found, since s a point iin PEA was considered c outtlier (SVF = 41 1.42%) (Figure e 3-a). Howev ver, for the com mparison betw ween SVF and the climatic c variables (Figure 3) the point of ma aximum fores st canopy ope ening monitorred in PAE will be considered, since in the t temperatu ure and humid dity box plots their data we ere used for the average calculation. he Figure 3 it is noted that in SGG in Observing th spiite of having similar canop py openness (13.26% ( e 14.66%), there is between b both monitored d points a gre eat temperature and relative e air humidity y variation. It demonstrates d the influence e of urban he eat in the forest fragment microclimate. The point with smaller nopy opennesss is less expo osed to the in nfluence of can urb ban microclima ate and prese ented an air temperature 3.0 0oC lower than n the point wh hich is in the area a under the e limits effect (less ( preserve ed). In ITA, as was w expected, the air temp perature is hig gher and the relative hum midity lower, consistent witth average SV VF higher than n the ones off the other are eas. With grreater canopyy exposure, the solar rad diation sufferss less attenua ation by the vegetation v foliiage reaching g the soil and d heating the air in the lev vel of the tru unks. Furthermore, as ITA A area is sm maller, the site is more suscceptible to the e influence of the t microclima ate of built are eas.

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(a)

(b)

However, in GER, located 500m from ITA, but toward the valley bottom, there is an average temperature 4.2oC lower than in ITA, maintaining great hygrothermal variation between the sample points. The SVF in ITA is also smaller, which may indicate a better preservation of this area when compared to ITA. Furthermore, ALE is 0.6ha larger than ITA. However, in S.JOS, where SVF is lower and was expected to have a milder microclimate, the air temperature and the globe temperature were maintained high when compared to the other areas. There is, however, a small temperature difference between the maximum and minimum average of the points, which was of 1.6oC. The same did not occur to the relative air humidity, for which there is a variation of 34.16% between the maximum and minimum average, which indicates the change in the absolute air humidity. Comparing GUA to PAE, both with the presence of water bodies, there are significant temperature differences, due to the point with high SVF in PAE, as previously mentioned. This point is possibly responsible for the average air temperature and globe temperature increase and the relative air humidity decrease in PAE. Furthermore, although PAE is 1.91ha larger than GUA, its conservation level is worse [12]. The low SFV is due to the occurrence of vines and slope inclination, and not exactly due to the foliage of the tree tops. 4.3. Canopy openness and the distance from the urban edge

(c)

Would the physical structure of forest canopy be modified according to the distance from a point to the urban limit? Presumably so, since the urban microclimate influence the microclimate of the forest fragments, affecting their conservation level. To answer this question, a correlation between SVF and the distance of the monitored points was sought, as presented in Figure 4.

(d) Figura 4: Correlation between Sky View Factor (SVF) and the distance from the point to the urban limit. Figura 3: Sky View Factor and climate and climatic variables (at 02:00pm) in urban forest fragments.(a)SVF (b) Air Temperature (c)Gray Globe Temperature (d)Relative Air Humidity

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A low correlation between the distance from the limits and the forest canopy openness was noted, even when analyzed separately. Possibly it occurs due to the small dimension of urban forest fragments, with the exception of SGG. Thus, the

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

physical structure of the canopy in the woods is little changed by distancing itself from the urban limits, since the distance is not more than 63m. Possibly in SGG there would be a less evident change in the forest structure, but for accessibility matters it was not possible to photograph its interior.

5. CONCLUSION The comparison of the microclimate of six urban forest fragments in the city of Campinas, Brazil, showed that average minimum temperature and daily temperature range are the variables that better express differences between the studies areas. With the increase in size (area) of the fragments there is a decrease in minimum air temperature and an increase in daily temperature range. However, it is worth noting that the monitoring points in Saint Geneve Grove, the largest urban forest reservation analyzed, were placed next to the urban limits, so that the thermal behavior observed may not be valid for points located in forest core, which are probably more thermally stable, for they suffer less influence from the urban microclimate. The areas of smaller dimensions suffer more daytime and nighttime heating, showing the influence of the urban microclimate in the forest microclimate. In the presence of water or next to valley bottoms, there is a decrease in air temperature. An interesting characteristic is that the globe temperature is very close to the air temperature inside the fragments. It occurs because the solar radiation is intercepted by the foliage of the plants and the small parcel which results in the understory tends to be diffuse. Thus, the soil and plants in the understory are poorly heated. The Sky View Factor (SVF), calculated from photographs of the forest canopy at the height of 1.5m, tends to decrease with the increase of the areas, which indicates an increase in leaf area and in the quantity of plants in larger areas. However, disturbance of the microclimate of the urban forest fragments cannot be explained only by SVF. It was noted that in Saint Joseph Woods, despite the low canopy openness, the maximum air temperature is high, which can happen either because of urban microclimate influence or because of the obstruction of the atmosphere by the tree canopy, which makes heat exchanges with the understory difficult. The temperature difference between the points located in these woods was small. Thus, the homogeneity of Forest structure associated with low canopy openness may indicate higher thermal stability, which is good for forestry management.

6.

ACKNOWLEDGEMENTS

The authors thank CAPES, for continued doctoral research schoolarship, Fundação Pedro de Oliveira for permission of research at Saint Geneve and Campinas City Hall for authorization of research in the public woods.

7. REFERENCES [1] MILLER, R. W. (2007) Urban Forestry: planning th and managing urban greenspaces. 2 ed. Waveland, Long Grove. [2] DACANAL, C.; MEULMAN, T.L.; LABAKI, L.C. (2010) Let's take a walk through the forest! Thermal comfort in urban forest fragments. Ambiente Construído, Porto Alegre (10), Apr. – Jun., pp. 115-132. [3] ABREU, L. V. ; LABAKI, L. C. (2008) Evaluation of the radius of influence of different arboreal species on microclimate provided by vegetation. In: Conference on Passive and Low Energy Architecture, 25th. Dublin, Towards Zero Energy Building. [4] BLUMENFELD, E. C. (2008) Relações entre Vizinhança e Efeito de Borda em Fragmento Florestal. Dissertação de Mestrado em Engenharia Civil. Campinas, UNICAMP. [5] KARLSSON, M. (2000) Nocturnal Air Temperature Variations between Forest and Open Areas. Journal of Applied Meteorology (39), June, pp. 851-862 [6] RAMOS, F.; SANTOS, F.M. (2006) Microclimate of Atlantic Forest Fragments: Regional and Local Scale Heterogeneity. Brazilian Archives of Biology and Technology, (49), 6, Nov., pp. 935-944. [7] LARCHER (2004). Ecofisiologia Vegetal. São Carlos, RiMa Artes e Textos. [8] GEIGER, R. (1966) The climate near the ground. Cambridge, Massachusetts, Harvard th University Press, 2 printing. [9] Frazer, G.W., Canham, C.D., Lertzman, K.P., (1999). Gap Light Analyzer (GLA), Version 2.0: Imaging software to extract canopy structure and gap light transmission indices from true-color fisheye photographs. Copyright 1999: Simon Fraser University, Burnaby, BC, and the Institute of Ecosystem Studies, Millbrook, New York; (http://www.rem.sfu.ca/forestry/index.htm or http://www.ecostudies.org). [10] LIMA, R.A.F. (2007) Regime de disturbio e de regeneração natural na Floresta Pluvial Atlântica Submontana. Dissertação de Mestrado em Recursos Florestais. Piracicaba, Universidade de São Paulo. [11] VELOSO, H.P.; RANGEL FILHO, A.L.; LIMA, J.C.A. (1991). Classificação da vegetação brasileira, adaptada a um sistema universal. Rio de Janeiro, Fundação Instituto Brasileiro de Geografia e Estatística - IBGE. [12] SANTIN, D.A. (1999) A vegetação remanescente no município de Campinas (SP): mapeamento, caracterização fisionomica e floristica, visando a conservação. Tese de doutorado em Ciências Biológicas. Campinas, Universidade Estadual de Campinas.

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Local Adaptation Processes to Climate Variability, Towards Living with Floods in the Padma River Bank Areas: The Case of Bangladesh. Amreen SHAJAHAN1, Md. Yousuf REJA2 1

Department of Architecture, Bangladesh University of Engineering & Technology, Dhaka, Bangladesh 2 Department of Architecture, Ahsanullah University of Science & Technology, Dhaka, Bangladesh

ABSTRACT: This paper outlines a part of a research and design project based on work undertaken for the B.Arch. at the Department of Architecture, Bangladesh University of Engineering & Technology in 2007-08. This paper devotes to discussing how the present floodplain residents live coping with floods, particularly in the flood-prone areas like Padma riverbank areas. The findings of the study on how these categories of residents cope with floods can be integrated into establishing official flood management measures to effectively manage flood disasters in flood prone areas which would greatly reduce flood losses. Floods in Bangladesh are a complex phenomenon. They pose enormous threats to the population through loss of life and economic damage, but at the same time, moderate floods contribute to the fertility of the land. Flood hazards of bank side areas of rivers are difficult to control through structural measures; Flood proofing through assistance to self help measures to reduce the damage to property and stress are largely accepted preventive efforts that these people have practiced. Adaptations towards the impact of climate change have made them quite self-dependent in facing disasters. A sample based survey in the selected case study area was done to make the plan efficient. This paper concentrates to heightening the community’s responsibility to sustain adaptation towards flooding and to proactively internalize the adaptation process. Keywords: local adaptations, flood proofing measures, vulnerability, coping strategies, riverbank area

1. PROLOGUE The South-Asian country of Bangladesh is prone to the natural disaster of flooding due to being situated on the Ganges Delta and the braided with many tributaries flowing into the Bay of Bengal. Due to its geographic location, the main physiographic feature of the country is its extensive floodplain system, which has been formed by the deposition of floodwater-laden silt carried by these rivers. Flow regimes of these rivers demonstrate large seasonal contrasts, inundating the floodplains each year during the monsoon season. At least Two-thirds of the country is less than 5 meters above sea level and in an average year, a quarter of the country is inundated [1]. Only the abnormal floods, the high magnitude events that cause widespread damage are the major environmental concerns facing Bangladesh. The severity of floods and other natural disasters has been increasing in Bangladesh due to climate change. Once every ten years roughly one third of the country gets severely affected by floods, while in catastrophic years such as 1988, 1998 and 2004 more than 60 percent of the country is inundated, that is an area of approximately one hundred thousand square kilometers for duration of nearly three months [2]. The main victims of flood disasters are the poor rural people who are 80 percent (2010) of total population have very little capacity to cope with the losses [3]. Due to limited resources, Bangladesh does not have the capacity to ensure appropriate measures to mitigate the damage. Floods periodically claim many thousands of lives in Bangladesh disrupt normal economic activities and

aggravate already-severe problems of poverty, health and quality of life. Floods in the Bangladesh are a complex phenomenon [4]. Normal floods are considered a blessing for Bangladesh-providing vital moisture and fertility to the soil through the alluvial silt deposition. Only abnormal floods are considered disastrous, i.e., the high-magnitude events that inundate large areas, and cause widespread damage to crops and properties. Successive severe floods in 1987 to till now stimulated the victims to set comprehensive activities to protect themselves from these calamities. This study has focused on understanding how different groups of people and communities perceive and respond to flooding risks in flood-prone countries like Bangladesh.

Figure 1: Study area located in the Map of Bangladesh. [5,6]

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The poor and vulnerable people are constantly adjusting to climate change by raising their houses above the flood level or changing crop types. This paper examines the household and community coping strategies used by the people beside Padma riverbank areas (Fig. 01) basically the low-income households living in ‘Hasail-Banuri’ union (P.S.Tongibari; District-Munshigonj) (Fig. 1), one of the highest flood prone areas in Bangladesh. This includes how they use physical and social means to reduce risks, lessen losses and facilitate recovery from flooding. The paper also discusses how local planning and governance mechanisms aimed at adaptation can support these coping strategies, including mainstreaming them into adaptation plans that can be scaled up to wide level.

2. PROBLEM STATEMENT Flood disasters are inherently a characteristic of natural hazards [7]. Disasters arise inevitably when the magnitude of a hazard is high. This contrasts with the alternative discourse that sees flood disasters as being jointly produced by interaction of the physical hazard and social vulnerabilities. This view posits that flood disasters are not only the result of natural hazards, but also of socioeconomic structures and political processes that make individual, families and communities vulnerable [8]. With 140 million people, Bangladesh is one of the world’s densest nations and also one of the most vulnerable to the impacts of climate change. The fourth report by the Intergovernmental Panel on Climate Change (IPCC) stated that Bangladesh would experience heavier monsoons and that the melting of Himalayan glaciers will cause higher river flows and severe floods [9]. Each year in Bangladesh about 26,000 km2, (around 18%) of the country is flooded, so far killing over 5000 people and destroying 7 million homes [10]. With the prospects of climate change the likelihood of extreme events like floods and cyclones may increase in future making Bangladesh even more vulnerable to these risks. The current trends in climate change have led to extreme environmental conditions that have caused the upheaval and displacement of millions of the most vulnerable people named “environmental” or “climate change” refugees (Fig. 2). However, based on past experiences, preparation of elaborate action plans is not the way to go. Rather, the country needs to take a few pragmatic actions which can be implemented and monitored.

Figure 2: Flood risks & damages. [11,12]

Bangladesh experiences two distinct types of inundations. The first one is river flood resulting from excessive runoff contributed by monsoon precipitation, which is normal events and the second one is coastal floods induced by storm surges of

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CLIMATIC, WATER AND BIODIVERSITY CONTEXT

tropical cyclones, which occurs once in every few years cause serious damages. Flood risk at a location depends upon the frequency of flooding and the associated consequences to the community. But most flood damage is caused by property and crop damage, followed by Lack of clean drinking water during a flood. To minimize flood losses, a number of modern engineering projects have been constructed within Bangladesh which has very limited results due to complex river system of Bangladesh and erratic behaviour of disasters. Again many structural measures have proved costly in environmental terms and failure or poor maintenance of some have even exacerbated flood hazards [13,14,15]. However, the successful solution of the problem would be probably encouraging and reinforcing various types of indigenous adjustments to floods.

3. THEORETICAL PERSPECTIVE ON VULNERABILITY & ADAPTIVE CAPACITY To conduct this analysis, this paper approaches the issue of disaster like seasonal flood from the point of view of vulnerability. The devastation caused by natural disasters like recurrent flooding in Bangladesh is, more a function of the social and economic characteristics of society or locality than of the actual physical repercussion of the catastrophe. Generally, vulnerability is seen as the outcome of a mixture of environmental, social, cultural, institutional and economic structures and processes related to poverty and (health) risk, not a phenomenon related to environmental risk only. Besides risk exposure, adaptive capacity is seen as a key component of the concept of vulnerability [16,17]. This adaptive capacity is a process of adaptation (over time) to structural and/or incidental sources of environmental stress [18], consisting of distinct social, economic, technological, institutional and cultural adaptive mechanisms [e.g. 19]. Minimizing or even preventing the cause of climate change is mitigation, while adaptation to the effect of climate change has become the key focus of policymaking in climate variability sectors. Since the mid 1990’s, the concept of social vulnerability is used to describe and analyze the exposure and coping mechanisms of groups and individuals to environmental risks, primarily in the context of climate change and flooding hazards in developing countries [20,21]. From the field of disasters, the term “coping capacity” is concerned with the means by which “people or organizations use available resources and abilities to face adverse consequences that could lead to a disaster” [22]. In the climate change field, IPCC discusses how under the scenario of a changing climate, risks may increase but adaptation actually expands a system’s coping ranges. Following on this, the IPCC uses the term “adaptive capacity” as the ability of a system to adjust to climate change (including climate variability and extremes), to moderate potential damage, to take advantage of opportunities, or to cope with the consequences [23].

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4. METHODOLOGY This paper aims to investigate the complex relationship between environmental risk and adaptive coping mechanism of the community. A case study carried out in one of the poorest and most flood prone countries in the world, focusing on household and community vulnerability. In a large-scale household survey carried out in the Padma River bank areas. Almost 198 hoses of floodplain residents living without any flood protections at ‘Hasail Banuri’ union in ‘Munshigonj' district. A stratified sampling procedure has applied to select the households during physical survey. Among the 28 households (surveyed), 18 were situated near the river edge, while the other 10 on higher ground near the main rural road. From the field survey, it reveals that, households with lower income and less access to productive natural assets face higher exposure to risk of flooding. Regarding the identification of coping mechanisms to deal with flood events, we look at both the beforehand household level preparedness for flood events and the afterward availability of community level support and disaster relief.

5. FLOOD EVENTS AREA

IN CASE STUDIED

The study area is located on the left bank of Padma River and 45 km south of Dhaka city (Fig. 1). This area had flooded every year and cause severe damages. The local people seem to have a strong sense of territory which has heightened when they face natural disasters like flood. These floods cause damage to houses, agricultural crops and the infrastructure in the area. For more than half of the rainy season around two thirds of the area remains under water. And during extreme flooding flood depth remain 1.8-3.6 meter and flood duration is 81-95 days [24]. As a result, employment opportunities decrease dramatically. In addition to regular seasonal flooding, the area suffered from devastating floods over the past 20 years in 1988, 1996, 1998, 2004 and 2007. Majorities of 94 percent of the interviewed floodplain residents are exposed every year during the rainy season to flooding, and a 42% of the population mentions flooding as the main problem faced by the region, followed by other important problems such as bad roads (18%), unemployment (26%) and lack of electricity (14%). The extent and level of flood exposure during the rainy season is severe. More than half of the population (58%) indicates that they suffer each year from diarrhoea and other health risks during the rainy season.

This village has a typical settlement pattern (Fig. 3) that prevails in the plain land of Bangladesh. Homesteads are raised above agricultural lands to protect houses from annual flooding. So land level is one of the major criteria for building houses and its design varies according to socioeconomic status of households. But almost all houses (Fig. 4) are built on stilts due to environmental reasons.

Figure 4: Plan & elevation of typical houses in study area.

6. INDEGENOUS MEASURES

FLOOD

ADAPTATION

6.1. Determinants of adaptive capacity The local people have adapted their lifestyle for centuries to live with river flooding, frequently moving their temporary bank-side homes, planting on newly emergent river bars, and sometimes raising their homesteads above water level in flood periods. For this reason, the quality of life notably poorer in these areas and this situation is worsened by floods. Thus they have prepared some non-structural floodproofing measures which have made them quite self dependent in facing disasters like flood. The impact of seasonal flood firstly depend on the probability of risk exposure through the distance (in meters) people live to the river at community level (the closer to the river, the higher the probability of flooding), secondly the state or condition of risk exposure through inundation depth (in meters) at individual household level, and thirdly the consequence of risk exposure through economic damage cost when the flooding occurs at individual household level. Disasters often acts as “means of change”, resulting for instance, in innovations in hazard resistant architectural and construction designs. In the study area, the most unique adaptation that has evolved in response to flood disasters is the stilt houses. These houses originally evolved as an adaptation to the occupation of swamp-land and frequent flooding in riverine areas. The survey results show that the majority of respondents took some corrective measures to minimize their flood looses. Some villagers received assistance from various sources (Fig. 5) to cope with flood hazards. Flood damage costs mitigated by taken measures aimed at preventing, avoiding or alleviating the physical and socio-economic impacts of flooding.

Figure 5: Sources of assistance received by the local flood victims of ‘Hasail-Banuri’ area during 2004 flood.

Figure 3: Planning layout of Hasail-Banuri Village (2007).

Flood preparedness plan is a series of sub-plans, including emergency response planning and training,

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raising public awareness, flood forecasting and warning, setting development policy, land use regulation, flood proofing, setting alternative plans, and local social structure strengthening. Community flood preparedness is an analysis of possible disaster scenarios for determining how authority and responsibility for action should be delegated, what local human and material resources exist, and how these can be deployed. Indigenous people, who are the vital & active parts of this ecosystem, are reacting to climate change impacts in a creative way from the very beginning. Peoples lived on this floodplain for centuries, have evolved many responses to reduce and mitigate flood disasters. Adaptation to extreme environments, including flooding is inherently a human survival trait. Effective flood responses are those that build on people’s existing ways of dealing with floods and complement their coping mechanisms, resources and social capital. Many flood-prone communities have local and traditional institutions dealing with disasters. 6.2. Physical coping strategies Adjustments to flood hazards in Bangladesh can be classified in different ways. Modern engineering flood control structures, such as embankments, levees, flood walls and polders, constitute structural adjustments that are intended to modify flood regimes significantly. In contrast, indigenous adjustments comprise all other measures - most of which are of the folk or preindustrial type, that are intended to adapt to natural flood regimes. Indigenous adjustments can be further classified into two distinct categories. First, indigenous flood proofing or flood adaptation may involve certain amounts of structural adjustments, such as raising homesteads above flood levels and the construction of animal refuges; but these activities are usually considered indigenous to contrast them with modern engineering structural measures . Second, agricultural adjustments refer to traditional cropping practices that have evolved for generations to adapt different crops to varied flood depths at different levels of the floodplains [25,26]. Table 1: Types of indigenous adjustments to floods at 2004 in case studied area.

A. Indigenous flood adaptations Raised homesteads

Padma Riverbank at 2004(%) 84

Raised floors Raised platform for temporary shelter Took shelter on major roads

94

Took shelter on other spaces Used bamboo bridges between houses Use boats/rafts

25 47

Vulnerable people individually and collectively develop their own means, resources and strategies to cope with flooding (Table 1). Coping strategies in this area is basically preventative as well as impactminimizing. In this area, the rural poor having no land ownership have no choice but to build beside the newly emerged sand bars beside the Padma riverbank areas (Fig. 6). These areas are highly susceptible to flooding. In this area houses are arranged in courtyard pattern (Fig. 3,6).

Figure 6: Courtyard housing beside the newly emerged sand bars close to the riverbank areas.

In the absence of adequate flood protection structures, the inhabitants of this floodplain in Bangladesh have developed a series of indigenous or traditional adjustments to floods. Most of these individual or collective adjustments are stated bellow. a) Temporary relocation to a safer area during a disaster: Some of them moved to higher lands or beside the main rural road side. In that sense, most of the households took few preventative actions before the disaster (Fig. 7).

Figure 7: Temporary location of houses beside the rural roadside (high elevation) created by two depressions areas (pond) at both sides.

b) Raising the homesteads: Digging earth from local depressions surrounding the homesteads in a dig-and-mound process where there is a productive by product is pond or depression area (Fig. 7). c) Build higher plinths, arrange higher storage facilities and increase the height of furniture:

Figure 8: Stilt houses with various stilt heights depending on location & water level during monsoon.

27 2 56

B. Agricultural adjustments Cultivated new rice crops Used bamboo fence to protect crops

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88 0 Figure 9: Height of the furniture (Bed) has increased due to protect the functional space from flood.

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In this area, most of the houses are on stilts (Fig. 8) due to extreme annual flooding. With stilts there is the flexibility to increase the height every time households rebuild, depending on the water level. Again households increased the height of the furniture (Fig. 9) by at least 1-2 ft (6–8 bricks) depending on the location of homesteads and they had created platforms (Fig. 10) at attic space or somewhere in-between due to storage purpose (food & water) during emergency. This type of raised platforms (Fig. 10) has also created in outdoors for storing vegetables for emergency and sometimes for domestic animals.

Figure 10: Raised platforms both in outdoor & indoor for storing purposes during emergency.

d) Building materials: Only very few households had changed to weather resistant building materials before rainy season like giving bituminous coal coating to lower part of the walls (Fig. 8) or vertical elements for water resistance. Wooden plank flooring is preferred as they suffer less from water-clogging and damages once the water subsides after heavy rainfall. e) Sanitation and water supply: Clean water-Flooding can contaminate water supplies, leading to potentially fatal diseases. There was only one raised tube-well for the villagers. f) Strategies after the flood disaster After a flooding and water-clogging event, 60% households had made alterations during the rebuilding of their structures, such as changing building and plinth materials, increasing plinth levels, and changing structural, roofing and walling materials. g) agricultural adjustments In this village, where farming is the main occupation, the locals have double use for their farming lots. The fields are located much lower than the land on which houses are built because wet paddy needs to be inundated by water most of the time. When the rivers overflow their banks, paddy fields act as a form of retention ponds. Local people had taken different measures (Fig 11) to protect their homesteads from erosion during flood.

working with local communities in this district to develop ways. Again, flood affected poor families were allowed to take shelter in village schools or higher local government buildings. Families who lose their home and livelihood moved to flood relief camps. Social capital, e.g., reciprocal support among neighbours, support from immediate family members and wider kinship networks, is a vital safety net for people in this area to cope with recurrent flooding.

7. CONCLUSIVE REMARKS Floods cannot be prevented but planning the emergency measures through flood management can often reduce their disastrous consequences. Flood risk reduction and response are more likely to be effective when they include coping mechanisms in the assessment and programme design. Programmes that directly support communities and their local organisations have proved to work best for immediate reinforcement of coping and resilience capacities [27]. In this paper, we investigated the complex relationship between environmental risk and vulnerability in a concrete case study carried out in one of the poorest and most flood prone countries in the world, focusing on household and community vulnerability and adaptive coping mechanisms. Coping with natural calamities like flooding is not a new situation for the rural people beside the riverbank areas, and much can be learnt from their autonomous responses (Fig. 12) in order to build local adaptation policies and plans in national level.

Figure 12: Example of flood resilient houses [28].

Localised solutions such as flood proofing have shown good results [29]. These local measures have been effective however; their extent is constricted because they are fragmented and uncoordinated. Even coping mechanisms can and do fail, and not just because this capacity is overwhelmed by the scale of flooding. Changes in population and economy, local environmental change and changes in flood regimes themselves can make mechanisms outdated. It is important not to over-romanticize indigenous capacities. Nevertheless, by incorporating these methods taken by the past residents into the official systems would greatly reduce flood losses. So lessons suggest that structural and non-structural measures for flood risk reduction should be integral parts of both the overall development process and disaster management

8. ACKNOWLEDGEMENT Figure 11: Sections showing local measures to protect landmasses from erosion due to annual flooding.

As a part of the community based adaptation to climate change, a number international NGOs are

Special acknowledgement to Prof. Dr Khandaker Shabbir Ahmed & Atiqur Rahman for their supervision & Department of Architecture, Bangladesh University of Engineering and Technology (BUET).

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9. REFERENCES [1] http://beta.worldbank.org/content/bangladesheconomics-adaptation-climate-change study,2.6.2010 [2] CEGIS (2002) Analytical framework for the planning of integrated water resources management. Center for Environmental and Geographic Information Systems, Dhaka. [3] http://www.theindependentbd.com/details.php?nid=173335 [4] Brammer, H. (1990) Floods in Bangladesh: I. geographical background to the 1987 and 1988 floods. The Geographical Journal, 156(1), 12-22. [5] Bangladesh Water Development Board.12 Oct 1998. www.bwdb.gov.bd/ [6] United Nations Institute for training and Research (UNITAR), 2007, www.unosat.org. [7] Dixit, A. (2003) Floods and vulnerability: need to rethink flood management. Natural Hazards, 28, 155-179. [8] Adger, N. W. (1999). Social vulnerability to climate change and extremes in Coastal Vietnam. . World Development, 27, 249-269. [9] IPCC (2007). Fourth Assessment Report. Geneva: Intergovernmental Panel on Climate Change. www.ipcc.ch [10] http://en.wikipedia.org/wiki/Floods_in_Banglades h [11] Nishat A. Guide for preparing local communities for flood management, unpublished, 2004. [12] http://knowledge.allianz.com/en/globalissues/clim ate_change/climate_2007/climate_2007_banglad esh_flood.html [13] Blaikie, P., Cannon, T., Davis, I. and Wisner, B. (1994) At risk: natural hazards, people’s vulnerability, and disasters. London: Routledge. [14] Smith, K. (1996) Environmental hazards: assessing risk and reducing disaster. London: Routledge. [15] Jain, N.K. (2000) Floods in a South Asian context: critical reflections on the International Decade and local community participation in flood disaster reduction. In Parker, D.J., editor, Floods. London: Routledge, 255–59.

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[16] Adger, W.N. (2000) Institutional adaptation to environmental risk under the transition in Vietnam. Annals of the Association of American Geographers 90(4), 738–58. [17] Intergovernmental Panel on Climate Change (2001) Climate change 2001: impacts, adaptation, and vulnerability. Summary for policymakers. A Report of Working Group II of the IPCC. Geneva: IPCC. [18] Nishat, A., Reazuddin, M., Amin, R. & Khan, A.R. (eds.) (2000) The 1998 flood: impact on environment of Dhaka city. Dhaka: Department of Environment and IUCN Bangladesh. [19] Cardona, O. (2001) La necesidad de repensar de manera holistica los conceptos de vulnerabilidady riesgo. Paper presented at International Conference on Vulnerability in Disaster Theory and Practice, Wageningen University, Netherlands, June 2001. [20] Blaikie, P., Cannon, T., Davis, I. & Wisner, B. (1994) At risk: natural hazards, people’s vulnerability, and disasters. London: Routledge. [21] Few, R. (2003) Flooding, vulnerability and coping strategies: local responses to a global threat. Progress in Development Studies, 3(1), 43. [22] United Nations International Strategy for Disaster Risk Reduction– UNISDR (2009), http://www.unisdr.org/eng/ terminology/terminology-2009- eng.html. [23] Adaptation and Vulnerability, Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK, 133–171, 869. [24] Institute of Water Modelling (IWM). www.iwmbd.org [25] Rasid, H. and Paul, B.K. (1987) Flood problems in Bangladesh: is there an indigenous solution? Environmental Management 11, 155-173. [26] Paul, B.K. (1984) Perception of and agricultural adjustments to floods in Jamuna floodplain, Bangladesh, Human Ecology 12, 3-19. [27] DipECHO (2004 The Evaluation of DIPECHO Action Plans in the Caribbean Region. Brussels: Directorate-General for Humanitarian Aid Disaster Preparedness Programme. apps.odi.org.uk/erd/ReportDetail.aspx?reportID= 3276 [28] D. Lumbroso1, D. Ramsbottom1, M. Spaliveiro (2008) Sustainable flood risk management strategies to reduce rural communities’ vulnerability to flooding in Mozambique, J Flood Risk Management, 1 [29] World Bank (2002) Bangladesh: disaster and public finance. Working paper series 6.Washington DC: World Bank. www.proventionconsortium.org/?pageid=37&publ icationid=6#6

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 1315 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Towards resilient urban ecosystems How resilience thinking can modify architect’s vision of sustainability and urban planning Hugo SORIANO1 1

Escuela Técnica Superior de Arquitectura, Universidad Politécnica, Madrid, Spain

ABSTRACT: Resilience is the ability of a system to absorb disturbance and still retain its basic function and structure. Since 2005, more than half of the world population lives in cities. It’s estimated that in 30 years time, this figure will most likely reach 80%[1]. Cities are the ecosystems were humans mostly live. In a world threatened by economic crisis, depletion of natural and ecological resources, diminishing biodiversity and climate change, sustainability depends on resilience. Resilience theories study complex social-economical systems, originally natural ones such as forests, coral reefs or lakes. After disasters like hurricane Katrina hitting New Orleans, or the Haitian earthquake, certain awareness about urban resilience has been raised. Focus and research on the resilience of urban ecosystems is needed. Why is resilience thinking important? Would it provide the opportunity for a “new” urbanism? What is being done, what can be done? What role can architects play? Keywords: resilience, urban, ecosystem, cities

1. INTRODUCTION Resilience thinking is largely based on the theories developed by Buzz Holling and colleagues since the 1970’s, when they studied forests as highly adaptive systems that go through regular cycles of growth, reorganisation and renewal. Their conclusions led to understanding that in many cases the efficiency and degree of interconnection within systems were inevitably accompanied by a loss of resilience, and that ultimately, an external surprise brings a change that can transform the system into a completely different, undesired one, due to the combined loss of resilience’s different cycles (for example, a fishery losing all fish, a forest not recovering after a fire, etc.). Holling and many others, clustered in the Resilience Alliance, believe the world reunites the conditions for a systemic crisis [2]; and that cities have all the conditions to be studied as ecosystems. The study of their resilience can help prevent undesired effects, encourage necessary transformations and sustainable development in a desirable sense. These considerations are already provoking urban initiatives, such as the transition towns movement or DRIFT.

people, ecosystems, knowledge systems, or whole cultures.” [3] Urban resilience is “the degree to which cities are able to tolerate alteration before reorganising around a new set of structures and processes [4]”. Holling and his colleagues like to represent the cycles which ecosystems go through with a 3dimensional figure. The cycle undergoes 4 phases, 2 compose the fore-loop, “Rapid Growth” and “Conservation”, and the other 2 the back-loop “Release” and “Reorganisation”. They happen at different scales, simultaneously and at different speeds. In conclusion a system is composed and/or related to many other variable systems, engaged in their own cycles, and nested to a certain extent: something described as panarchy.

2. RESILIENCE AND PANARCHY 2.1. What is resilience According to the Stockholm resilience centre, Resilience is “the capacity to deal with change and continue to develop. Resilience refers to the capacity of a social-ecological system both to withstand perturbations from, for instance, climate or economic shocks, and to rebuild and renew itself afterwards”. Loss of resilience can cause loss of valuable ecosystem services, and may even lead to rapid transitions or shifts into qualitatively different situations and configurations, evident in, for instance,

Figure 1: The loop of adaptive cycles

As ecosystems develop, they start in rapid growth exploiting “new opportunities and available resources” [5] to engage in the Conservation phase,

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where stakeholders of the system have established and gradually optimised their available resources while increasing their connections and reinforcing relationships, reducing space for novelty. This process is accompanied by an increase in the efficiency and specialisation every stakeholder has in exploiting available resources, and a subsequent higher regulation. “The growth rate slows as connectedness increases, the system becomes more and more rigid, and resilience declines” [5]. An unexpected event can then break apart the web of reinforcing interactions, thus undoing the system. An example in ecosystems would be fires, drought, diseases or insect infestations. In this phase, there’s creative chaos, or destruction, but also new opportunities for reorganisation. The problem is that systems have thresholds in their transformations. Thresholds are “levels in controlling variables that feedback to the rest of the system changes” [5]. Once a system crosses a threshold, it can start functioning under completely different rules, and this can happen after a certain amount of nested cycles have lost enough resilience to ultimately not recover to the previous situation. Thus a clear water lake can become a murky water lake, usually because of a combination of conditions that change even if the state of the system doesn’t. (Fig.2, 3)

Figure 2: The system as a Ball in the Basin Model

consider the role of surprise. Nevertheless, there is a tendency to emphasise known computable aspects of a problem while neglecting aspects that are unknown and failing to ask questions about them. The tendency to ignore the non-computable can be countered by considering a wide range of perspectives, encouraging transparency with regard to conflicting viewpoints, stimulating a diversity of models, and managing for the emergence of new syntheses that reorganise fragmentary knowledge.” [6] Resilience thinking takes into account diversity. Diversity is very different from the culture of optimisation that tends to monoculture, dominance of the few, and dominant solutions. Nothing is more contemporary in our interconnected world than a tag cloud, a comprehensive way to have a multilateral approach to a problem, considering nested systems and variables. Resilience can be apprehended in practical terms with modern representation tools such as real-time visualisation tools but also social networks and associations. (Fig. 4)

Figure 4: The tag cloud as a representation of a diversity of models

Contemporary representation is complex, and studies related to sustainable development are also probabilistic and scenario oriented. The Millennium assessment, the World Economic Forum Global Risks Report or companies like Shell, they all work with scenarios and probabilities related to varying conditions as ways to orientate sustainable development. Resilience thinking proposes the appropriate framework for establishing these scenarios.

3. URBAN RESILIENCE Figure 3: The Basin changes shape

In conclusion, systems develop in nested cycles where specialisation results in a reduction of redundancy vs. higher efficiency, less flexibility and loss of resilience. Why is resilience thinking an adequate tool to study urban ecosystems? As it is well pointed out in the paper, Resilience: Accounting for the Non-computable: “Plans to solve complex environmental problems should always

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Urban planning driven by single political/economical forces is hardly representative and certainly incapable of adequately responding to the complexity of urban ecosystems. As described by the Resilience Alliance “Urban landscapes represent probably the most complex mosaic of land cover and multiple land uses of any landscape and as such provide important large-scale probing experiments of the effects of global change on ecosystems (e.g. global warming and increased nitrogen deposition). Urbanisation and urban landscapes have recently

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011 th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

been identified by the Millennium Ecosystem Assessment as research areas where significant knowledge gaps exist”. Recent natural disasters (e.g. Hurricane Katrina (Fig. 5) and the Asian Tsunami) and social disturbances (e.g. London Bombings and September 11) have highlighted the need for urban systems to cope with unexpected shocks. While there is an emerging research focus on sustainable cities (urban landscapes), there remains a poor scientific understanding of the processes and factors that make some cities vulnerable to shocks and others resilient. This may be due in part to the fragmented nature of urban science and policy” [7]

Figure 6: Urban resilience themes

Figure 5: New Orleans after the Katrina

A renewed form of urban science is being created to study cities as ecosystems and design positive strategies. The architect’s approach to building and sustainable development can be central in this process since they already have (in spite of strong specialisation) a naturally holistic approach to planning. This opens an opportunity for architects after, in the words of Rem Koolhas, “the death of urbanism -our refuge in the parasitic security of architecture-” [8] has been digested, as well as the assumption of the relatively new, humbled position of the architect after its rise in the rationalist modern movement. For, again to quote Koolhas, “If there’s to be a “new urbanism” it will not be based on the twin fantasies of order and omnipotence; it will be the staging of uncertainty, it will no longer be concerned with the arrangement of more or less permanent objects but with the irrigation of territories with potential; it will no longer aim for stable configurations but for the creation of enabling fields that accommodate processes that refuse to be crystallised into definitive form”[8] 3.1. Research themes The resilience alliance has identified a series of research themes they are currently working on. They will be cited here not as a guideline, but as a reality in which a cluster of scientists of different disciplines are working and that architects can participate in. This will be reviewed concisely because the scope of the subject is too large to embrace in this paper. The following diagram shows these themes as an interconnected whole. (Fig.6)

xx.x SECTION NAME

Metabolic Flows studies are concerned with the critical interconnections and interdependencies along the chain of production. Incidents like the Longford explosion, due to a research of optimal efficiency, halted natural gas supply in Melbourne for more than 2 weeks and led to the wasting of 25 Million litres of milk that couldn’t be pasteurised. It’s a typical case where optimal efficiency and lack of redundancy (alternate sources) led to greater damage. This theme focuses on understanding what the city consumes and produces (energy, food, waste, etc.). Main questions are Diversity, (whether it provides larger resilience) Disturbance, (response to shocks and surprises including when produced in distant geopolitical zones) Metabolism, (is recycling the solution?) and Connectivity (how does high connectivity and feedback create resilience, if it does at all?). Social dynamics studies are mainly related to demography, the role of population, its composition and diversity. Challenges come both from relentless growth (in Africa or Asia) to negative growth (Italy and Spain), social marginalisation and protests. Main questions are Demography, (how do immigration, social change and turnover contribute to the resilience of urban sub-regions and the system as a whole?) Distribution, (how does the placement of populations affect resilience? how does modularity of populations work vs. connectivity with the associated degree of social inequity? Are the poorest always the most vulnerable to shocks and surprises?) Diversity, (do populations with a higher degree of diversity in culture, age and education have a higher level of social capital in terms of organisational knowledge and life experience, to withstand rapid-onset shocks? Governance networks “Urban decision making, institutions, and land use practices are increasingly shaped by civil society represented by NGOs, universities, research centres, industry and informed citizens” [7] The rapid growth of cities and their transformations, coupled with shifts of governance from larger scales to local, even communal scales, their overlaps and good or bad practices lead us to think that “urban decision makers should be less concerned with prediction and control, and more concerned with organic, adaptable and flexible urban management” [7]

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Questions are: Evolution, (what patterns and lessons emerge from governance dynamics emerging from old cities that can enhance resilience?) Components, (how do social networks and organisations interact with urban institutions and influence resilience?) Cross scale-effects (how do changes of scale and cross scale effects influence governance, as cities are formed or evolve?) Lock-in and change, (can surprises cast opportunities for governance and change the existing inequalities and urban marginalisation?) Built environment is the theme most traditionally attached to architects. The static regulations of urban planning occurring within political ideologies have dynamics that are opposed to the fast changes and complex interactions inherent to the city. “To a large extent, we live in “yesterday’s cities” in the sense that many of the urban patterns we see today reflect decision making periods of the past” [7] It’s needless to explain that urban planning and spatial organisation of the city has significant influence on the flow of commerce and people in and out of cities. “The spatial pattern of the cities is both created by chance and necessity” [7] For the resilience alliance, the following questions arise: “Pattern and diversity – What is the role of ‘green-space’ or ‘semi-natural ecosystems’ (kinds, amounts, patterns) in promoting sustainability, reducing vulnerabilities, and building resilience? Path dependency – With the many examples of path dependant dangers in urban systems, could irreversible changes have been identified in advance, and are there particular attributes of the systems that identify or suggest such non-return points? Can resilience theory on regime shifts and thresholds help identify key attributes of the system to monitor and inform decision making? Rates of change – How can urban planning ‘blueprints’ be made compatible with the speed of urban system change, and can self-organisation be specifically addressed and included? When faced with difficulties or failures in the urban environment, what structural or social responses emerge, and how do we learn from these so as to guide rather than control urban development? Sizes and patterns – Can the world’s megacities keep growing? How does the emergence of extended urban regions (megapolitan regions) influence urban resilience? Is there an optimal density and/or optimal layout for cities and how might this vary according to social-ecological context? And how does the regional pattern of other city sizes influence urban growth trends?” [7]

4. APPLICATIONS The interpretation of urban resilience can be used for many purposes. Its multi-dimensional focus is compelling and contemporary. The source of its motivation is disturbing: a challenge is set for our planet’s sustainability, its resilience needs to be secured. Resilience thinking can be detoured to encourage security and restriction of personal freedoms. It can also lead voices to partially return to

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previous states of underdevelopment for mankind, because there are many ecologists that, in their love of nature, oppose everything related to science and development.[9] It opens the door to sheer traditionalism and refusal of novelty. 4.1. Transition towns movement

Figure 7: Transition initiatives UK

According to the transition network website, “A Transition Initiative (which could be a town, village, university or island etc) is a community-led response to the pressures of climate change, fossil fuel depletion and increasingly, economic contraction. There are thousands of initiatives around the world starting their journey to answer this crucial question: "for all those aspects of life that this community needs in order to sustain itself and thrive, how do we significantly rebuild resilience (to mitigate the effects of Peak Oil and economic contraction) and drastically reduce carbon emissions (to mitigate the effects of Climate Change)?" Transition initiatives are one of the most popular resilience thinking derivatives. Initiated by Rob Hopkins, it has developed a lot in the UK and USA, counting more than 500 cities with initiatives at this point in time.(fig. 7) The movement is founded at a local level. Small activist groups start a labour of environmental transformation following a protocol (established by the Transitions network) that has a lot of down-toearth wisdom and common sense. The application of these principles will supposedly allow to create awareness and connect to the rest of the community with the aim of establishing bridges with local authorities, encouraging the community to develop the main themes of life (food, energy, transportation, health, spiritual and physical well-being, economy and lifestyle), build resilience; and eventually lay mid term plans (20 years or so) that will contribute, in collaboration with other towns, to create a new society. This initiative sometimes feels naive, others plainly reactionary; but has growing adepts, is ambitious in its marginality, and it has become possible thanks to internet-powered social networks, global consciousness and anti-globalisation. If, like the studies led by Paul Hawken [9] indicate, there’s

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011 th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

more than one million associations around the world that combine in their credo, elements of social justice and environmental concern, we can quickly see the potential that this kind of “marginal” initiative can have. Alter-governance led by NGOs acting in a kaleidoscope of interdependent situations, evolving in nested cycles, connected yet modular, diverse and redundant, offer a panorama that resonates with panarchy theories. Some architects can integrate this processes, as they have in many self-construction initiatives (i.e. Alejandro Aravena), acting as mediators in the reconfiguring of these new towns. 4.2. DRIFT DRIFT stands for Dutch Research Institute for Transitions. It is related to various initiatives promoted by the Erasmus University Rotterdam, the Technical University Eindhoven and the University Amsterdam. It’s an academic, scientific-oriented version of the practical transition town movement with shared objectives: piloting the transition process our society has to obligatorily go through. Through a series of publications exposed in a website [11], they have grouped the main transition themes in 4 groups: Food, Health, Energy and Automobiles. The automobile appears here as a problem over which actions can have noticeable impact in relatively short time. The urgency of action makes possible encouraging ideas that, out of our current context, wouldn’t be taken into consideration. Automobiles configure urban models, some now recognised as public enemies, such as sprawl. Watching a documentary like “The end of suburbia” [12] leaves us with mixed feelings. There’s the necessity of creating awareness of a bad model (urban sprawl) but encouragement of a traditional “European” model, based on density. One has to be careful when suggesting models, for the method of reasoning is still bound to be mono-focused, monocultural and non-responsive...This is precisely what resilience thinking allows, seeing opportunities in the future to enable radical action in front of surprises, and prepare for a sustainable, inevitable and desired transformation.

5. OPPORTUNITIES At this point, architects can find space, maybe because cities and building are their specialty, where, ironically, a “significant gap of knowledge” [13] exists. We can only blame our own profession for such a gap, publicly described by expert ecologists. We could be victims of treasuring our own knowledge, wanting to protect our own field of work to keep the upper hand. But if we leave behind Henri Roark and the parasitic architect, maybe we can find a renewed social role (although this might be too ambitious) through resilience thinking. As pointed out by Juan Freire, the architect could be an integrator in the new urbanism that agglutinates potentialities proposed by empowered citizens, technology-enhanced social networks and representation methods. [14], become an expert in communication and conversation, abandoning the

xx.x SECTION NAME

marketing model of persuading images at which all are more or less experts already. For example, take the automobile, a theme of concern for DRIFT. Architects like MVDRV have seen an opportunity to propose an utopian model of city, maybe too formal and far from reality, but that proves nevertheless that there’s room for the debate about the car in large scale terms, that there are alternatives in industry that are working already on new car concepts. Architects can integrate and hopefully contribute to the evolution of transportation and subsequent city transformations using the resilience lens as an argument of “objective” value.(Fig.8)

Figure 8: Skycar city. MVDRV architects

More opportunities are opened by the work of MIT’s Senseable City Lab. Their study during the World Cup finals of 2006 in Rome showed the potential of mobile phones coupled with new representation tools. By mapping the position of human beings in their environment, the possibilities opened by gathering and processing real-time data both as consumers and producers are many. For instance, the amount of phone calls during that final allowed representation of an exceptional event in the city, with the possibility of adequately responding to it, for example, with the surplus of transportation at the right time. Similar representation tools such as Usahidi or Urban atmospheres enable great possibilities for real-time urbanism. The possibilities opened by these tools and democratic information, as well as the eventual backlashes, are yet to explore. An example is provided also by tools like Oakland crime-spotting website map, it provides real time information of where crimes happen in the city, empowering stake-holders to focus on local problems with urban planers, decision-makers and architects. Space syntax is, in this sense, an office that has been working for years with this kind of data, their decisions deduced from parametric computer analysis of many conditions observed on site. (Fig. 9)

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7. REFERENCES

Figure 9: Lebanon Masterplan. Space Syntax.

6. CONCLUSION This paper has studied urban resilience as a science with the ambition of better understanding our cities. It opens up exciting possibilities about urbanism. But it has failed to deal with one of the most disturbing realities: Informal cities. Many of the possibilities opened by new technologies have to address the fact that more than a billion people live in informal cities; and a billion more are expected to come there [9]. Their ecological footprint hasn’t been studied, their future needs, neither. Their resilience is based on an enormous capacity of self reconstruction after disasters, at the cost of their inhabitants. Being deprived even of the most basic tenure of their premises, the poor of global slums have hardly any rights, yet they live in an ecosystem where nothing is wasted, nobody is unemployed and things somehow work. Slums could be saving our cities as a buffer against unsustainable energy and material demands. Their study and the lessons to be learnt to improve their needs in security, health, energy and food, might be essential in determining the resilience of our future urban ecosystems.

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[1] United Nations (UN) (2009). The World Population Prospects: the 2009 Revision. Department of Economic and social affairs. The United Nations. New York. [2] T. Homer-Dyxon. Our panarchic future. [online]URL:http://www.worldwatch.org/node/60 08 [3] [online]URL:http://www.stockholmresilience.org/r esearch/whatisresilience [4] Alberti, M., Marzluff, J.M., Shulenberger, E., Bradley, G., Ryan, C. and Zumbrunnen, C. (2003). Integrating Humans into Ecology: Opportunities and Challenges for Studying Urban Ecosystems. BioScience, 53: 1169-1179. [5] B. Walker and D. Salt (2006) – Resilience thinking – Sustaining Ecosystems and People in a Changing World. Island press, Washington DC [6] Carpenter, S. R., C. Folke, M. Scheffer, and F. R. Westley. (2009). Resilience: accounting for the non-computable. [online]URL:http://www.ecologyandsociety.org/v ol14/iss1/art13/ [7] A Resilience Alliance Initiative for Transitioning Urban Systems towards Sustainable Futures [online]URL:http://www.resalliance.org/1610.php [8] Rem Koolhas and Bruce Mao S,M,L,XL Whatever happened to urbanism?”:959-971 [9] Stewart Brand: Poptech conference. [online]URL:http://www.poptech.com [10] [online]URL:http://www.transitionnetwork.org/ [11] [online]URL:http://www.sustainabilitytransitions.c om/en/background [12] Gregory Greene - The End of Suburbia: Oil Depletion and the Collapse of The American Dream [13] McGranahan et al. (2005).Millenium Ecosystem Assesement, Island press, Washington DC [14] Juan Freire “Urbanismo emergente :ciudad, tecnología e innovación social” Paisajes Domésticos / Domestic Landscapes, Vol. 4 Redes de Borde / Edge Networks. Ed. SEPES Entidad Estatal de Suelo, Spain.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Sustainable Urban Planning of High Density Cities by Urban Climatic Mapping An Experience from Kaohsiung, Taiwan CHAO REN, KA LUN LAU, KAM PO YIU, EDWARD NG School of Architecture, The Chinese University of Hong Kong, Hong Kong, China ABSTRACT: There is a need to create sustainable urban development and quality living environment for the increasing urban population of high density cities. Sustainable urban planning of high density cities from the urban climatic point of view has been a topical issue for city planners and policy makers. However, the application of urban climatic knowledge has a low impact urban planning and policy decision making of urban development. This is especially true in high density cities of developing countries. Thus, there is an urgent need to seek for ways to assemble quickly urban climatic information for planning actions in a format that is userfriendly to planners. The study has identified ways to promote the use of urban climatic knowledge in planning. By utilizing readily available data, the paper introduces a method that focuses on urban planning using the Urban Climatic Map (UCMap). UCMap provides a visual and spatial information platform on planner-friendly Geographical Information System. By focusing on Kaohsiung, Taiwan, the study first defines the urban climatic issues in the area. It then introduces the key methodology of urban climatic mapping and elaborates on the general urban climatic-based planning advices using the UCMap. Lastly, it identifies the sensitive areas and provides planning recommendations that can be easily adopted by city planners. The actionable importance of urban greenery and coverage, urban air paths and open spaces, water bodies and rivers, and building morphologies and layouts, have been highlighted for planners. Keywords: urban climatic map, high density city, sustainable urban planning

1. INTRODUCTION Cities have become bigger in size and more densely populated nowadays as characterized by their compact urban fabric and enormous urban population [1, 2]. Such phenomenon is more prominent in high density cities where urban development has become more unsustainable and living quality of urban environment is declining [3]. Although scientifically-based urban climatic studies have been widely conducted, the consideration of urban climatic environment is still limited in the decision-making process of urban planning. One of the major drawbacks preventing the consideration of urban climatic environment in planning processes is the assemblage of urban climatic information for planning purposes and the translation of working languages between scientists and urban planners [47]. From planners’ perspective, the following difficulties have been encountered when dealing with urban climatic issues in planning processes: (i)climatic information cannot be easily understood by planners and designers due to their non-scientific background [6, 8]. Numbers and equations are difficult to be comprehended or translated into semantic language for policy applications; (ii)it is not easy to reconcile numerical precisions in scientific terms with rough and synergetic thresholds commonly required when a number of concerns must be concurrently considered; (iii)at the city level, urban climatic conditions with spatial information are not normally visualised for policy decision-making [9]. (iv)climatic evaluations and knowledge are not

normally elaborated into planning language; (v)effective mitigation measures are not clear or practical in planning context [8]; (vi)as a result, there is an urgent need for an immediate assemblage of urban climatic information for planning purposes in the way that can be easily recognized by urban planners and government officials [8]. The collation and presentation of such information are also important in the formulation of planning and policy decision-making with regard to urban climatic environment. The emergence of Urban Climatic Map (UCMap) offers a possibility for this agenda [8, 1012]. This study aims to enhance current understandings by developing a map-based planning tool for high density cities, using Kaohsiung City, Taiwan as an example (Fig.1). It will fill the knowledge gap to identify the relationship between urban climatology and morphology, and to construct a framework of climatic-environmental evaluation and to apply the useful result into Taiwan urban planning system.

  Fig. 1. The map of Kaohsiung city, Taiwan

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

2. BACKGROUND

Urban Heat Island Intensity

2.1. Urban climatic map

Natural Landscape

The concept of UCMap was first developed by German researchers in the 1970s [13] and have been widely conducted in Europe, Asia, and South America since the 1980s. Urban climatic map is an information and evaluation tool that integrates urban climatic factors and urban planning considerations by presenting urban climatic phenomena into a twodimensional spatial map and in a format that can be easily interpreted by urban planners. The scales of UCMap applications normally vary from 1:100,000 to 1:5,000, precisely fitting urban planning into a wide range of scales ranging from regional, city, to neighbourhood scales [14, 15]. It collates meteorological, planning, land use, topographic, and vegetation information. Their inter-relationships and effects on urban environment are also analysed and evaluated spatially and quantitatively [15, 16]. Based on such information, various ‘climatopes’ can be defined in which the spatial distribution of urban climatic characteristics and their significance can be easily interpreted [12, 17, 18]. Sensitive areas with urban climatic and environmental problems can be identified so that relevant strategic urban planning recommendations can be formulated in order to assist urban planners to take appropriate actions.

3. METHODOLOGY 3.1. Theory In the present study, urban climatic, environmental, and planning parameters, as well as their impacts, are considered in order to synthesize and comprehensively evaluate the physical urban environment (Table 1). Topography, population density, land use, and UHI intensity contribute to the variations of the thermal environment and are therefore categorised as thermal loads. Dynamic potential consists of natural landscape, seas, and rivers reflecting potential for air ventilation and air mass exchange in Kaohsiung. The prevailing wind information and local land and sea breezes are coded and evaluated as ‘Wind Information’, providing a comprehensive understanding of the wind environment of Kaohsiung. The synthesized effects of thermal load, dynamic potential, and wind information result in various ‘Climatopes’. Climatopes refer to urban areas with similar urban climatic conditions and implications for planning decisionmaking [15, 19], which are mainly defined and differentiated by land use and urban morphology [16, 18]. Table 1: Selected Parameters and Their Impacts on Urban Environment Physical Urban Environment Thermal Environment

Selected Analysis Factors Topography Population Density Land Use

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Impact on Urban Environment Negative impact on thermal load Positive impact on thermal load Positive/ Negative impact on thermal load

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Water Body Wind Environment

Prevailing Wind Information Local Wind Circulation

Positive impact on thermal load Negative impact on thermal load Positive impact on dynamic potentials Positive impact on dynamic potentials Positive impact on dynamic potentials

3.2. Procedures and data collection A three-step analysis has been conducted using GIS as the data platform. The use of the GIS platform ensures that urban planners can eventually assess and utilise the data as it has been one of the major working tools of urban planners.

  Fig.2. Main Procedures of the UCMap Study

The workflow of the present study is summarised in Fig. 2. First, climatic, environmental and planning data and information were collected from various government authorities such as Taiwan Central Weather Bureau, Urban Development Bureau, and Department of Budget, Accounting, and Statistics of Kaohsiung Local Government. Secondly, data collation was then performed and data was interpreted and resolved to form the basic input layers of UCMap. The input layers of various selected parameters were then synergized and merged to generate the UCMap of Kaohsiung. It is composed of various climatopes that spatially represent thermal conditions and wind environment of the city. Based on the urban climatic understandings of the UCMap, problematic and sensitive areas were identified. With the collaboration of urban planners, a number of general urban climatic planning recommendations were elaborated at urban scale.

4. RESULT The UCMap of Kaohsiung is composed of eight basic layers with input data unified and rasterized into grid cells of 500 m × 500 m. This provides a preliminary area-based understanding for urban planners who work out further planning decisions at district and neighbourhood scales. 4.1. Layer 1: Topography Air temperature decreases with height at a rate of 10°C/km for rising air (i.e., adiabatic changes in temperature occur due to changes in pressure of gas while not adding or subtracting any heat) [20]. The moist adiabatic lapse rate is relatively lower at a

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

value of 0.6°C/100m (Aikawa et al., 2006). This layer therefore represents the topographic height in metres according to the data obtained from the Urban Development Bureau of Kaohsiung Government [2123]. The relatively flat topography of Kaohsiung City suggests that only two small hills need to be represented. Due to their possible temperature variations and thermal stress contributions, three UCMap classes have been identified: 0-150 m, 151300 m, and over 300 m (Fig. 3a). 4.2. Layer 2: Population Density Population density contributes in the intensity of androgenic activities and is known to correlate with the urban thermal environment [24, 25]. Building density and volume must therefore increase to accommodate the increasing population. In general, an urban area with a higher density of buildings has poorer urban ventilation conditions and stronger UHI effects [26, 27]. Population density contributes to the understanding of thermal loads in the UCMap. This layer (Fig. 3b) represents the population density in persons per km². Based on the data obtained from the Department of Budget, Accounting, and Statistics of Kaohsiung Government (Tseng, 2008; Yap, 2008), it was deduced that the highest population density in Kaohsiung reaches above 30,000 persons per km². Given this high-density scenario [28], this layer was defined as high density, moderate high density, or extreme high density (Fig. 3b).

a)Layer 1;

b)Layer 2;

Fig. 3. a) Topographical Map, b) Population density map of Kaohsiung City

4.3. Layer 3: Land use Urban thermal environment is influenced by land use, which determines a wide range of urban parameters, such as building form, urban density, anthropogenic heat releases, energy consumption, and transport behaviours. Based on the Land use and Planning Data acquired from the Urban Development Bureau of Kaohsiung Government and Geography Atlas of Kaohsiung City [27], the layer on land use was rasterized and created (Fig. 4a). The grid cells were respectively classified as climatopes which form the basic units of the UCMap. The classification of this layer is based on their similarities in urban climatic characteristics for different land uses, such as thermal capacity, surface roughness, and anthropogenic heat release [15].

4.4. Layer 4: Urban Heat Island Intensity The phenomenon of UHI is commonly observed along with the temperature difference between urban and rural areas [29]. UHI is defined as a metropolitan area having a significantly higher temperature than its surrounding rural areas [24, 30, 31], which can be more significant when wind or air ventilation is weak [25]. Based on the study by Taiwanese researchers using traverse mobile measurements [32], the UHI intensity in Kaohsiung is about 2.5-3.0° C. Using computational fluid dynamics model simulation [33, 34], their study results were collated and rasterized, resulting in six classes of layer ranging from very high to very low UHI intensity (Fig. 4b).

a)Layer 3;

b)Layer 4;

Fig. 4. a) Land Use Map; b)UHII Map of Kaohsiung City

4.5. Layer 5: Natural Landscape Natural vegetation has a beneficial cooling effect to its surrounding areas and can therefore lower thermal load (Oke, 1987, 1988; Landsberg, 1981; Bowne and Ball, 1970; Brook, 1972). The classification of this layer (Fig. 5a) is based on the parks and types of greenery coverage [22, 35, 36]. Areas of no vegetation are classified as very low, while limited coverage is classified as low. Grasslands, agricultural, and military lands, which can provide considerable cooling effects to surrounding areas, are classified as medium. Large urban parks, which contribute to the cooling of surrounding urban built-up areas, are classified as high. Forests or large woodlands are classified as very high. 4.6. Layer 6: Water Body Systems In the construction of large-scale climatic maps, the distance measured from the coastline for sea breezes is factored in [37]. Kaohsiung has a long coastal line with Love River running through the central urban area and Lianchih Pond in the inland area. Some paddy fields and fishponds are found in the northern part of Kaohsiung City. There are two small canals, Yansheigang Canal and Cianjhen Canal [35]. The classification of this layer is based on the potential effects of the different types of water systems, such as seas, rivers, lakes, and fishponds (Fig. 5b).

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

a)Layer 5;

b)Layer 6;

Fig. 5. a) Natural landscape Map; b) water body Map of Kaohsiung City

4.7. Layer 7: Prevailing Wind Information The prevailing wind information is important in the design of urban settlements. It also has great potential in improving urban thermal environment and in solving problems related to air pollution. Thus, the prevailing summer and annual wind directions are considered in the study. According to the historical meteorological record, the mean wind speed in Kaohsiung city is relatively low at around 2.7 m/s throughout the year [35, 36, 38]. Annual wind directions are mainly from the N, WNW, NEN, S, and SES; summer wind directions are mainly from WNW, W, ENE, E, and SES. In Fig. 6, the blue arrow shows the prevailing annual wind directions while green arrow shows the prevailing summer wind directions.

Fig.7. Layer 8: Land & Sea Breezes Map of Kaohsiung City, after [33, 34]

4.9. The Urban Climatic Map Based on the eight input layers, the UCMap of Kaohsiung was synthesized based on the evaluation of urban climatic data (Fig. 8) and composed of different climatopes, the basic units of the UCMap. Land uses were first differentiated for better planning-based understandings, including areas for commercial/business, residential/education, and industrial, as well as water bodies and greeneries. Within such land use types, various areas of similar climatopes are delineated and described. The different climatopes are affected by its constituent parameters of urban morphology, population density, topography, greeneries, and water bodies. Their contributions to the urban thermal environment are likewise differentiated. For example, for commercial/business districts, areas are classified from very high to low thermal load.

Fig. 6. Layer 7: Prevailing Wind Map of Kaohsiung City

4.8. Layer 8: Land and Sea Breezes Effect Since Kaohsiung is a coastal city, land and sea breezes are prominent and have a potential to improve the urban thermal environment. Land breezes come from ENE, N, and SES directions at night. High wind velocity areas focus on inland areas such as the eastern part of Zuoying District and Cianjhen District. Sea breezes come from WNW, W, and S directions during daytime. Thus, high wind velocity areas concentrate on the waterfront areas, for example, the outlet of Love River in Cianjin District. In Fig. 7, red arrows in the left figure show the land breeze at night while blue arrows in the right figure show the sea breeze during daytime.

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Fig.8. UCMap of Kaohsiung

By referring to the UCMap in Fig. 8, three levels of planning action at the city, urban, and neighbourhood scales were suggested with the collaboration of urban planners. Coding their descriptions in planning terms was employed. Level 1: Central Kaohsiung, including Cianjin, Yancheng, and Sinsing Districts, has very high thermal load and low dynamic potential. This suggests that these areas have intense

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

anthropogenic heat releases but have limited air ventilation. These areas require specific planning actions such as increasing greenery coverage and reducing anthropogenic heat releases. Level 2: Medium planning is required in the districts of Lingya, Sanmin, Cianihen, and Siaogang, since high to medium thermal stress and higher dynamic potential are observed in these areas. Provision of greenery is encouraged, while anthropogenic heat releases must be reduced. In particular, air pollution due to industrial activities requires specific attention. Industrial restructuring should be considered in these areas. Level 3: For areas with low thermal stress and high dynamic potential, such as Zuoying, Nanzih, Cijin, and Gushan Districts, the current situations should be preserved and the provision of surfaces of low albedo is encouraged. Since the availability of air ventilation is higher in these areas, air exchange with surrounding urban areas is encouraged. In particular, potential air pollution problem in Nanzih requires specific attention.

5. DISCUSSION 5.1. Advantages As a means to assist city planners, developers, and policy-makers, the UCMap shows how urban climatic planning recommendations on an urban spatial scale can be formulated. To summarize, the methodology and procedures introduced in the present study have several advantages: (i) the structure of UCMap system, which consists of input layers and a final evaluation map, is flexible and is easily managed. All climatic, environmental, and planning information is collated and evaluated with the same grid size embedded into the GIS framework. Thus, further urban climatic, environmental, and planning information can be updated and managed easily; (ii)the selected parameters are easy to collect, and the study results are useful for planners; (iii)according to the UCMap, various climatic data and environmental information are presented spatially for convenient interpretation of urban planners. Problem and sensitive areas can be easily identified. Further detailed studies can focus on any particular aspects or localities; (iii)the UCMap provides an information platform for interdisciplinary study. It presents visually and spatially the aforementioned evaluation, which could then assist in future planning decision-making and policy implementations; (iv)urban climatic information is translated into planning-based language and actionable strategies. 5.2. Limitation and Further Studies A number of limitations are identified to guide future studies: (i) the resolution of UCMap is at a grid of 500 m × 500m. The general effective control measures and planning strategies can only be implemented onto the master plan at the urban level. (ii) for certain planning studies, the UCMap evaluation at the 500-m grid is rather coarse. Hence, from time to time, there is a need for focused understanding and studies. This has been the case

for Tokyo where, based on the Tokyo Thermal Environmental Map, further studies on wind paths were conducted in specific areas (Kagiya and Ashie, 2008). (iii) further empirical and model simulation data are needed to better quantify the map so that the degree of control can be better established. After knowing ‘what to do’ and ‘where to do’, planners must know ‘how much one needs to do’.

6. CONCLUSION The urban climatic environment of Kaohsiung has never been studied systematically at the urban level and applied to the Taiwan Planning System [39]. In this study, a demonstration to quickly draft an UCMap was presented and quick reference to urban planners has become possible. With readily available data, eight urban climatic and planning parameters were considered. They were collated into GIS layers and evaluated quickly for their respective thermal and dynamic contribution to the urban environment. Planning recommendations in planning language – air paths and open spaces, water body and rivers, greenery and landscaping, and urban morphology – were explained. These could assist planners in making their design decisions. Furthermore, an actionable plan was presented that is suitable for planners. As such, the study achieved the agenda of promoting the use of urban climatic knowledge in planning. Currently, some detailed planning parameters, such as site coverage and building volume density, were not considered. The resolution of Kaohsiung city UCMap is at 500 m x 500 m, a dimension that can be improved in the process.

7. REFERENCES 1. 2. 3.

4.

5.

6. 7. 8.

UN, World Urbanization Prospects. The 2001 Revision. : United Nations. Kraas, F., Megacities and Global Change in East, Southeast and South Asia. ASIEN, (2007). 103(S): p. 9-22 Ng, E., Policies and technical guidelines for urban planning of high-density cities - air ventilation assessment (AVA) of Hong Kong. Building and Environment, (2009). 44(7): p. 1478-1488 Oke, T.R., Towards a Prescription for the Greater Use of Climatic Principles in Settlement Planning. Energy and Buildings, (1984). 7: p. 110 Mills, G., Progress toward sustainable settlements:a role for urban climatology. Theoretical and Applied Climatology, (2006). 84: p. 69-76 Eliasson, I., The use of climate knowledge in urban planning. Landscape and Urban Planning, (2000). 48: p. 31-44 Bitan, A., Climatic Data Analysis and its Use and Reprsentation for Planners. Energy and Buildings, (1984). 7: p. 11-22 Cleugh, H., et al., Climate and Sustainable Cities: Climate Information for Improved Planning and Management of Mega Cities

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9. 10. 11.

12.

13. 14. 15.

16.

17.

18.

19.

20. 21.

22.

23. 24. 25. 26.

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(Needs and Capabilities Perspectives). World Climate Conference-3: Geneva, Swiztherland. Bitan, A., The Methodology of Applied Climatology in Planning and Building. Energy and Buildings, (1988). 11: p. 1-10 Baumüller, J., et al., Klimaatlas Region Stuttgart: Stuttgart, Germany: Verband Region Stuttgart. Katzschner, L.andJ. Mulder, Regional climatic mapping as a tool for sustainable development. Journal of Environmental Management, (2008). 87: p. 262-267 Baumüller, J., et al., Climate Atlas of a Metropolitan Region in Germany Based on GIS, in seventh International Conference on Urban Climate. 2009: Yokohama, Japan. Matzarakis, A., Country Report: Urban Climate Research in Germany. IAUC Newsletter 11. Katzschner, L., The Urban Climate as a Parameter for Urban Development. Energy and Buildings, (1988). 11: p. 137-147 VDI, VDI-Guideline 3787, Part 1, Environmental Meteorology-Climate and Air Pollution Maps for Cities and Regions, ed. VDI: Beuth Verlag, Berlin. Alcoforado, M.J., et al., Application of climatic guidelines to urban planning -The example of Lisbon (Portugal). Landscape and Urban Planning, (2009). 90: p. 56-65 Baumüller, J., U. Hoffmann, and U. Stuckenbrock, Urban Framework Plan Hillsides of Stuttgart in seventh International Conference on Urban Climate. 2009: Yokohama, Japan. Scherer, D., et al., Improved concepts and methods in analysis and evaluation of the urban climate for optimizing urban planning process. Atmospheric Environment, (1999). 33: p. 41854193 Baumüller, J., U. Hoffmann, and U. Reuter. Climate booklet for urban development, Ministry of Economy Baden-Wuerttemberg (Wirtschaftsministerium), Environmental Protection Department (Amt für Umweltschutz). 1992 [cited. Golany, G.S., Urban design morphology and thermal performance. Atmospheric Environment, (1996). 30(3): p. 455-465 Fung, W.Y., et al., Derivation of Nighttime Urban Air Temperatures Using a Satellite Thermal Image. Journal of Applied Meteorology and Climatology, (2009). 48: p. 863-873 KCG, Guide Book of Kaohsiung Parks and Greenery Areas : : Kaohsiung, Taiwan: Public Works Bureau, Kaohsiung City Government (KCG). KCG, Kaohsiung Digital Map and Planning Data. 01 Jun: Kaohsiung, Taiwan: Urban Development Bureau, Kaohsiung City Government. Oke, T.R., City size and the urban heat island. Atmospheric Environment (1973). 7: p. 769-779 Oke, T.R., Boundary Layer Climates. 1987, London, Routledge. Givoni, B., Climate considerations in building and urban design. 1998, New York: Van Nostrand Reinhold. xiv, 464.

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27. Huang, H., ed. Geography Atlas of Kaohsiung City, in Chinese. 2001, Research, Development and Evaluation Comission of Kaoshiung City: Kaohsiung City. 28. UN, World Urbanization Prospects: Data Tables and Highlights. The 2001 Revision. ed: Population Division, Department of Economic and Social Affairs, United Nations Secretariat. 29. Landsberg, H.E., The urban climate. International geophysics series ; v. 28. 1981, New York: Academic Press. x, 275 p. 30. Oke, T.R. Urban heat islands: an overview of the research and its implications. Urban Heat Island Summit 2002 [cited; Available from: www.city.toronto.on.ca/cleanairpartnership/uhis_ summit.htm. 31. Oke, T.R., The energetic basis of the urban heat island. Quarterly Review of the Royal Meteorological Society, (1982). 108(455): p. 124 32. Lee, K.P., A Study on Urban Heat Island of Four Metropolitan Cities in Taiwan. 1999, National Cheng Kung University: Tainan. 33. Li, Y.-y., The Practices and Perspectives of Kaohsiung Ecocity: Our Approaches in Taiwan, in Twin City Sustainable Development Forum: Hong Kong and Kaohsiung. 2009, The Chinese University of Hong Kong. 34. Li, Y.Y., et al., New paragon of Urban Design: "Innovation Practice of urban Development toward Environmental Ethics"- The strategical orientation and evaluation of ecocity and green community in Kaohsiung. Architecture Dialogue, (2009): p. 126-135 35. Sun, J.J., The Blue Ribbon and Green Ribbon of Kaohsiung City. 36. Chen, T.-W., The Study of Relationship between Urban Identity and Landscape Structure on the Natural Environment in Kaohsiung City in Graduate Institute of Urban Development and Architecture. 2006, National University of Kaohsiung: Kaohsiung. 37. Svensson, M.K., S. Thorsson, and S. Lindqvist, A geographical information system model for creating bioclimatic maps - examples from a high, mid-latitude city International Journal of Biometeorology, (2003). 47: p. 102-112 38. Huang, S., Research Report: New Planning of Aozihdi Urban Downtown Areas: Taipei, Taiwan: Department of Civil Engineering, National Taiwan University. 39. Tseng, T.-F., Plan of Changing Urban Space of Kaohsiung City, ed. K.C.G. Bureau of Urban Development: Kaohsiung, Taiwan.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Urban Climatic Map and STEVE Tool for Sustainable Urban Planning in Singapore Steve Kardinal JUSUF1, Nyuk Hien WONG2, Chun Liang TAN1 1

Center for Sustainable Asian Cities, National University of Singapore, Singapore 2 Department of Building, National University of Singapore, Singapore

ABSTRACT: Extensive urbanization has resulted in economic, social, energy & environmental problems. The trend in global population increase leads to an increase in demand for housing. Natural land has been replaced with artificial surfaces in most cities around the world with undesirable thermal effects. This, together with growth in industrialization, has caused a deterioration of the urban environment. Urban heat island (UHI) phenomenon has become a common problem in many major cities worldwide. Urban climate is one of elements of urban physical environment, which is often ignored in urban planning. To design a sustainable city, it is necessary to factor the climatic information holistically and strategically into the planning process. Sustainable urban development emerges as one of the main issues to tackle the UHI problem and to increase energy saving of buildings. At the building level, many building energy simulations have emerged to provide energy assessment for building during the design stage. However, the challenge remains for the estate development. Combining the air temperature prediction models and urban climatic mapping method, a framework is developed as an assessment tool to help urban planners in their design process. Since the 1970s, the concept of urban climate map (UCMap) has been developed by German researchers, which have a strong focus on applied urban climatology. It is considered as an appropriate tool for translating climatic phenomenon and problem into 2-D images and symbols with land use and spatial information for the urban planning use. It can help urban planners, architects and governors to understand and evaluate the effect of urban climatic issues on decisionmaking and environment control. The Screening Tool for Estate Environment Evaluation (STEVE) was developed with a motivation to bridge research findings, especially air temperature prediction models, and urban planners. STEVE is a web-based application that is specific to an estate and it calculates the Tmin, Tavg and Tmax of a point of interest for the existing condition and future condition (proposed master plan) of an estate. By combining these two methods, urban climatic map and STEVE Tool will help creating a more sustainable urban planning. Keywords: urban climatic map, STEVE Tool, sustainable urban planning, microclimatic condition, Singapore

1. INTRODUCTION In 2008, more than half of the world population is living in the urban areas and the numbers are estimated to grow up to 5 billion people by year 2030 [1]. The problem of urbanization is not an exception to Singapore, which extends beyond its border to its neighbouring countries and even to its regional South East Asian countries. Known as a politically stable and the safest country in Asia, Singapore attracts a large pool of foreign talent and traders from all over the world. Furthermore, the government has a plan to increase the population to 6.5 million in 4050 years from the current 4.5 million inhabitants. Urbanization in the recent years has significantly increased the number of buildings, in which ameliorate the urban microclimate. As In the past decades, urban heat island (UHI) phenomenon in the city and its corresponding issues including the mitigation methods have become the main research topics in the area of urban climatology. Researchers have conducted various investigations and measurements in the urban environment such as temperature, wind condition inside the urban canyons, urban greeneries, shadowing effect, anthropogenic heat generated by buildings and traffics, etc. Prediction models such as impact mitigation strategies, urban air temperature

predictions, improved weather forecasting and air quality forecasting have been developed as a result. Singapore, known as a City in the garden, is also not spared from the UHI problem. Based on the island-wide mobile survey, the highest air o temperature of 28.4 C was found in the Central Business District (CBD) area that has less vegetation. A higher air temperature was also observed in the industrial area. The UHI intensity is o up to 4.5 C [2]. Singapore is relatively new in adopting the urban climatic mapping method for its urban development as compared to some other countries, for example Germany, which has been using this method for more than two decades. The history of adopting this urban climatic mapping method in Singapore starts from the necessity of developing an assessment tool, used by urban planners and decision makers. Singapore has various research projects related to the built environment, such as urban heat island, thermal benefits of parks, rooftop garden, vertical greenery et cetera. The lesson learnt from these research projects interrelate one to another and urban climatic mapping method is found to have the ability to wrap them all together into an assessment tool that provide benefits in developing an environmentally sustainable Singapore.

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Figure 1: Sketch of UHI profile in Singapore [2]

This paper highlights the estate level urban climatic mapping of Singapore from the background condition of Singapore, such as its urban heat island phenomenon, development of air temperature prediction model and the application of urban climatic mapping for an estate development.

2. URBAN CLIMATIC MAP 2.1. At nation/city level Climate is an existing factor in a built environment and the study about climate condition is to improve the climate condition and to reduce the negative microclimate effects. There are two different difficulties appear for the climatic study. First, there is no suitable data available as the usual meteorological measuring net is too wide. Second, there is only a little or no time for the planners to make decisions and so is the available time for the meteorological investigation [3]. Germany is one of the leading countries in urban climate research. The first urban climate study was th conducted in Berlin as early as in the end of 19 century and used several methodologies in the later studies including thermal imaging, temporary weather station, car transverses, vertical soundings and constructions of urban climatic map (UC-Map) in the early 80s [4]. Among the various methods, UC-Map is found very useful for urban planning purpose since it integrates the urban climatic factors and urban planning considerations. Before this methodology was developed, the integration was a problem in many cities, because both have different domain of knowledge. Meteorologists do not know the planning

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requirement that consider the urban climate factor, while urban planners do not understand the type of climate data that can be provided for their planning purpose [5]. As an information and evaluation tool, the UC-Map has two components, the Urban Climatic Analysis Map (UC-AnMap) and Urban Climatic Recommendation Map (UC-ReMap). The UC An-Map compiles the meteorological data, land use, building footprint information, topography and vegetation information, in which, their effects on thermal load and thermal comfort are analyzed and classified spatially into several categories [6]. Figure 1 shows the workflow and data required to develop UC-AnMap for urban climatic map of Hong Kong as an illustration. Urban Climatic Recommendation Map (UCReMap) is specific for planning purpose. It provides strategic and city planning guidelines to improve the microclimate condition based on the UC-AnMap and practical constraints. Similar climatopes obtained from UC-AnMap are grouped into classification zones, where each zone is represented in different colors and has specific planning guidelines, such that the urban climatic condition will not be worsened or even improved. Hence, the collaboration between the urban climatologist and the planners is very important in the development of UC-ReMap from UCAnMap [7]. The recommendation map can be in a form of general guidelines, for example in Stuttgart climatic map, transformation of green space and vegetation into the built city to preserve and reclaim natural vegetation in order to improve ventilation, reduce the release of air pollutants and support fresh air provision (Figure 3) [8]. The scale of the UC-Map is 1:100,000 for the regional analysis and 1:5,000 for district analysis. It provides an overall analysis, in

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

which, microclimate study can be selected and conducted.

  Figure 2: Workflow of UC-AnMap development for Hong Kong [5]

Figure 3: UC-ReMap City of Stuttgart [8].

2.2. At estate level Urban climatic map at the estate level provides a more detail climatic condition, i.e. urban air temperature, as compared to urban climatic map at city level, as it usually has the scale of 1:5,000 to 1:100,000 with the resolution of 100m grid.

Known as temperature map, its methodology was developed based on the findings that the urban air temperature in the urban areas has a close relationship with the land uses [9], which physically is related to the urban morphology characteristics, such as: sky view factor [10-14], greenery condition [15-

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16], thermal mass of the built environment [17-18], building materials [19-21]. Daily minimum (Tmin), average (Tavg) and maximum (Tmax) temperature of a location point were calculated as the result of temperature deviation from the temperature measured at meteorological station. The deviation is mainly due to the urban morphology characteristics, i.e. building, pavement and greenery, within the radius of 50 meters. The independent variables for the models can be categorized into: 1. Climate predictors: daily minimum (Ref Tmin), average (Ref Tavg) and maximum (Ref Tmax) temperature at reference point; average of daily solar radiation (SOLAR). For the SOLAR predictor, average of daily solar radiation total was used in Tavg models, while average of solar radiation maximum of the day was used in the Tmax model. SOLAR predictor is not applicable for Tmin model. 2. Urban morphology predictors: percentage of pavement area over R 50m surface area, average height to building area ratio, total wall surface area, Green Plot Ratio, sky view factor and average surface albedo.

The planners are not able to modify the overall climate condition, but they modify the urban morphology condition. With the temperature map, planners are able to analyze the impacts of their design to the environment. As an example, temperature map study was used to analyze and predict the impact of a new master plan as compared to the existing condition in a Singapore estate and also to study two different greenery density of the park, named as “Green Belt”. The calculated maximum temperature is shown in Figure 4. The changes of maximum air temperature distribution pattern at different master plan models (Model 1 and Model 2) are mainly due to the change of greenery and building distributions. The removal of large greenery area and replace it with buildings increases the average temperature condition, as seen in the Vista Xchange zone. The impact of Green Belt in Model 2 (Figure 4 right) that has a higher greenery density as compared to Model 1 (Figure 4 middle) seems more noticeable, creating a larger “cool island” in the middle of the estate.

Figure 4: The calculated average air temperature of current condition (Left), master plan model 1 (Middle) and master plan model 2 (Right).

3. SCREENING TOOL FOR ESTATE ENVIRONMENT EVALUATION (STEVE) TOOL Researchers have conducted various investigations and measurements in relation to urban and built environment. As the results, they have come out with various prediction models for different

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purposes, including impact mitigation strategies, climate predictions, improved weather forecasting and air quality forecasting [22]. Nevertheless, these prediction models are too complicated for educated non-scientists, such as urban planners. At the end, they are often kept in the shelves until the scientists are engaged to do the assessment. By the time scientists finish their assessments, the planners have

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

no time to redesign their master plan based on the scientists’ findings. There is a gap between scientists and planners. Furthermore, at building design level, CAD software has been developed and integrated with some simulation software, called as Building Information Modeling (BIM). However, at urban or estate planning level, there is still no software or tool that can equip planners to design and perform assessment at the same time. These findings emphasize the need to develop a tool for planners. The Screening Tool for Estate Environment Evaluation (STEVE) was developed with a motivation to bridge research findings, especially air temperature prediction models, and urban planners. STEVE is a web-based application that is specific to an estate and it calculates the Tmin, Tavg and Tmax of a point of interest for the existing condition and future condition (proposed master plan) of an estate. The air temperature prediction models that have been briefly mentioned above were used in this application. The map of estate’s existing condition or future development is displayed in STEVE interface. The viewing level of the map is set into three levels. In level 1 (Figure 5), it displays a complete estate map including the zoning boundaries, which are darkened when the mouse is pointed to the selected zone. Users are able to zoom-in the map into the second view level by clicking either the selected zone or the zoom-in button (Figure 6).

Figure 6: Second viewing level of the map

Figure 7: Third viewing level of the map

Figure 5: First viewing level of the map

The designated points appear for the users’ selection in this viewing level and then, users are able to predict air temperatures condition by clicking the selected point. A circle with the radius of 50 meters blinks to provide indication of urban morphology distribution that has the influence on air temperature at the selected point (Figure 7). At the left hand side of the existing or proposed master plan map, Calculator interface appears with preloaded values of different parameters for the selected point (Figure 8). The preloaded values can be changed according to users’ need and the predicted air temperature results will appear with a push on the “Calculate” button.

Figure 8: Calculator interface

4. CASE STUDY A new master plan of a residential area has been announced. Temperature values (Tmin, Tavg and Tmax) used in developing the predicted temperature are interpolated with reference to temperature reading from NUS Weather station on 6th March 2010 which is considered fairly clear and hot weather. The selection is based on the analysis of that day, measured air temperature and precipitation. Singapore daytime is considered as from 8.00 to 19.00 hours, while night time is considered from 20.00 to 7.00 hours.

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night time, the urban heat island phenomenon. The empty sites simulated with turfing show high temperatures during the day because turfing is unable to provide shading. But, it prevents the bare soil heated up and during night time, it cools faster than the roads.

 

Figure 9: New residential development

Table 1: Climate predictors from NUS weather station on 6th March 2010 (Source: NUS Weather Station, 2010) Date Min. Temp at reference point (Ref Tmin) Avg. Temp at reference point (Ref Tavg) Max. Temp at reference point (Ref Tmax) Total solar radiation (SOLARtotal) Max. solar radiation (SOLARmax)

6 March 2010 25.49oC o

27.98 C

Average Temperature

o

31.2 C

Figure 11: Predicted average temperature

5062.945 W/m 683.5 W/m

2

2

5. SIMULATION RESULTS

Minimum Temperature Figure 12: Predicted minimum temperature

Maximum Temperature Figure 10: Predicted maximum temperature

The maximum, average and minimum temperature maps are shown in Figure 10-12. The maximum temperature map shows that the built-up areas have cooler temperatures than the open areas. The shadow casted by the buildings lowers the temperature of spaces surrounding the buildings. On the other hand, the minimum temperature map represents the night time temperature, shows the built-up area has the higher temperature as compared to the open areas. The heat absorbed by the buildings is released to the environment during

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Figure 12 shows the predicted temperature conditions in a well-planted residential precinct. The vegetations around the buildings help moderating the temperature. During daytime, the trees provide shading and reduce the direct solar radiation to the environment. Meanwhile, the evapotranspiration process of the trees reduces the temperature during night time (minimum temperature map). 

6. CONCLUSION Urban climate is one of elements of urban physical environment, which is often ignored in urban planning. To design a sustainable city, it is necessary to factor the climatic information holistically and strategically into the planning process. Sustainable urban development emerges as one of the main issues to tackle the UHI problem and to increase energy saving of buildings. At the building level,

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

many building energy simulations have emerged to provide energy assessment for building during the design stage. However, the challenge remains for the estate development. Combining the air temperature prediction models and urban climatic mapping method, a framework is developed as an assessment tool to help urban planners in their design process.

7. ACKNOWLEDGEMENTS This research study is funded Ministry of National Development together with Housing Development Board (HDB) under research grant number R294000-030-490

REFERENCES [1] Laski, L. and Schellekens, S. Growing up urban. In Marshal, A. and Singer, A. (eds.), The state of world population 2007 youth supplement. (2007). United Nations Population Fund (UNFPA). [2] Wong NH, Chen Y. Tropical urban heat islands: Climate, buildings and greenery. New York, Taylor & Francis 2009; pp 52-67. [3] Katzschner L. The urban climate as a parameter for urban development. Energy and buildings 1988; 11: 137-47. [4] Matzarakis A. Country Report Urban Climate Research in Germany. IAUC Newsletter 2005; 11: 4-6.

field observations. Journal of Climatology 1981; 1: 237-254. [13] Bärring I, Mattsson JO, Lindqvist S. Canyon geometry, street temperatures and urban heat island in Malmö, Sweden. International Journal of Climatology 1985; 5: 433-44. [14] Chapman L, Thornes JE, Bradley AV. Rapid determination of canyon geometry parameters for use in surface radiation budgets. Theoretical and Applied Climatology 2001; 69: 81-89. [15] Chen Y, Wong NH. Thermal benefits of city parks. Energy and Buildings 2006; 38: 105-120. [16] Streiling S, Matzarakis A. Influence of single and small clusters of trees on the bioclimate of a city: a case study. Journal Arboriculture 2003; 29: 309-16. [17] Knowles RL. Energy and form: An ecological approach to urban growth. USA: The MIT Press 1977. [18] Giridharan R, Lau SSY, Ganesan S, Givoni B. Lowering the outdoor temperature in high-rise residential developments of coastal Hong Kong: the vegetation influence. Building and Environment 2008; 43: 1583-595. [19] Berdahl P, Bretz S. Preliminary survey of the solar reflectance of cool roofing materials. Energy and Buildings Special Issue on Urban Heat Islands and Cool Communities 1997; 25: 149–58.

[5] Mayer H. Results from the research program “STADTKLIMA BAYERN” for urban planning. Energy and buildings 1988; 11: 115-2.

[20] Taha H, Akbari, H, Rosenfeld A, Huang J. Residential cooling loads and the urban heat island-the effects of albedo. Building and Environment 1988; 23: 271-83.

[6] CUHK. Urban Climatic Map and Standards for Wind Environment - Feasibility Study. Working paper 1A: draft urban climatic analysis map. CUHK: Hong Kong. 2008; pp 13.

[21] Taha H. Modeling the impacts of large-scale albedo changes on ozone air quality in the south coast air basin. Atmospheric Environment 1997; 31: 1667-76.

[7] CUHK. Urban Climatic Map and Standards for Wind Environment - Feasibility Study. Working paper 1A: draft urban climatic analysis map. CUHK: Hong Kong. 2008; pp 19-38. [8] Climate booklet for urban development. Ministry of Economy Baden-Wurttemberg in Cooperation with Environmental Protection Department of Stuttgart; 2008. [9] Jusuf SK, Wong NH, Hagen E, Anggoro R, Yan H. The influence of land use on the urban heat island in Singapore. Habitat International 2007; 31: 232-42. [10] Cleugh H. Urban climates. In: Henderson-Sellers A, Ed. Future Climates of the World: A Modeling Perspective. Amsterdam and New York: Elsevier, 1995. [11] Arnfield AJ. Street design and urban canyon solar access. Energy and Buildings 1990; 14: 117-31. [12] Oke TR. Canyon geometry and the nocturnal urban heat island: comparison of scale model and

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ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

City Planning with Urban Wind in Complex Coastal Cities – an experience of Hong Kong EDWARD NG, XIPO AN School of Architecture, The Chinese University of Hong Kong, Hong Kong, China ABSTRACT: Hong Kong is one of the world’s highest-density cities, with over sixty thousand persons per square kilometer in its urban areas. High-rise, bulky and closely packed buildings are the norm. This reduces urban air ventilation. Since 2003, the Hong Kong Government has commissioned studies using the method of air ventilation assessment (AVA). One of the key issues regarding the AVA assessment and the planning quest for better urban ventilation is a need for a better understanding of the wind environment. In a nutshell, what kind of wind are we designing for in our city? What are the characteristics of this wind? This paper elaborates efforts to understand Hong Kong’s wind environment based on a detailed analysis of Hong Kong observatory’s ten year wind data. It can be concluded that designing for the available wind can be a very complicated matter especially when the city is affected by various phenomena like topography, land and sea breezes, and so on. Keywords: urban wind environment, high density city, urban planning

1. INTRODUCTION High density city design is a topical issue. There is a need to deal with the scarcity of land, to design for a viable public transport system, and to re-build the community of our inner cities. High density living is increasing an issue that planners have to confront with. Hong Kong is a high density city with a population of 8 millions living on a piece of land of 1,000 square kilometres. The urban density of Hong Kong is close to 60,000 persons per square kilometre. The site development density can be up to 3000 persons per hectare (Figure 1).

greenery, are coined as measures in the Team Clean Report 2003 to improve the built environment. The report also highlights the need to establish an objective assessment method of urban air ventilation to guide future planning actions. [1]

 

 

Fig. 2. Incorporate breezeways and air paths into the city fabric is one of the many design measures to improve the city’s urban air ventilation.

Fig. 1. The high-rise cityscape of Hong Kong.

The unfortunate events of Severe Acute Respiratory Syndrome (SARS) in 2003 have brought the Government and inhabitants of Hong Kong to the realization that a “quality” built environment should be an aim for Hong Kong. Gradation of development height profiles, provision of breezeways (Figure 2), layout planning and disposition of building blocks to allow for more open spaces, greater building setbacks to facilitate air movement, reduction of development intensity, increase open space provisions especially in older districts and more

In 2006, the Government of Hong Kong promulgated the Air Ventilation Assessment (AVA) Method that has now been adopted in Hong Kong to guide developments. [2] Wind Velocity Ratio (VRw) is used as an indicator. V∞ is the wind velocity at the top of the wind boundary layer not affected by the ground roughness, buildings and local site features (typically assumed to be a certain height above the roof tops of the city centre and is site dependent). Vp is the wind velocity at the pedestrian level (2m above ground) after taking into account the effects of buildings. Vp/V∞ is the Wind Velocity Ratio (VRw) that indicates how much of the wind availability of a site can be experienced and enjoyed by pedestrians on ground taking into account the buildings in between. As VRw is solely affected by the buildings of the location, it is a simple indicator one may use to assess the

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

effects of proposals – higher the value of VRw, lesser the impact of buildings on wind availability. [3] (Figure 3)

 

Fig.4. Locations of Hong Kong Observatory wind stations.

This first cut understanding demonstrates the complex wind field of Hong Kong due to the seasons, topography and the land and sea breezes. Based on the reference wind station of Walgan Island (WGL) at the bottom right corner of Figure 3 and 4, annually, winds come from the East and north-East. In the critical summer months, winds come from the SouthWest. Hence, if streets have to be aligned with the winds, it is obvious that it needs to be orientated North-East South-West.

VRi 

V pi V i

  V R  w   

  16



i 1

 

Fi  V R i

Fig. 3. The figures show how VRi and VRw are calculated

The wind performance understanding of the AVA method replies on the V∞, being the wind velocity at the top of the wind boundary layer not affected by the ground roughness. This is the synoptic wind of the city. In order for the city to capture this avail-able, its directions and speeds are important to note; and since AVA is a weak wind assessment method, the directions of the available wind at low and medium speeds are of greater concern. The simple wind velocity ratio understanding of Figure 3 is typically employed by wind engineers dealing with wind load and wind safety studies. [4] [5] It basically assumes a simple and unchanged relationship (or ratio) understanding of V∞ and Vp. Using models in wind tunnel, this simple relationship can be scaled and tested. Whilst the understanding has served wind engineers well conducting tests under strong wind conditions, a problem is that this simple and constant relationship may not hold under all wind conditions, especially under weak wind conditions, and in complex topographical conditions.

Fig.5. Wind roses of Hong Kong Observatory wind stations (summer months of June to August). The topography of the land is shown. The highest mountain is about 1000m above sea level.

2. OBSERVED WIND The Hong Kong Observatory observed data serves as the first step understanding the available wind of the city. There are more than 40 stations positioned in various places in Hong Kong (Figure 4). The data is extracted and presented as wind roses in Figure 5 and 6).

 

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Fig.6. Wind roses of Hong Kong Observatory wind stations (annual).

 

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The problem with this understanding is that in many parts of Hong Kong, the wind directions are different. For example, in the Victoria Harbour (inserted diagram at the bottom right hand corner od Figure 4), a strong channelling effect can be observed. Hence it is more important for streets to be East West orientated.

3. TOPOGRAPHY Hong Kong has a complicated topography. Topographical variations in close proximity of the project site means that care must be exercised to determine the characteristics of the site wind availability for pedestrian level thermal comfort understanding. Take a zoom in area of Figure 5 as an example (Figure 7). The sheltered project site is indicated by the RED circle. It is surrounded by complicated topographical features. Using MM5/CALMET model simulation, the annual wind roses at 10m, 30m and at 450m above ground are captured in Figure 8, 9 and 10 respectively. The slow shift of wind directions as shown in the wind roses is apparent. Hence if the direct scaled relationship between V∞ and Vp that is typically employed by wind engineers is applied, the shift in wind directions will not be accounted for. For weak wind studies where the wind directions are the more important consideration, the understanding of the ground level wind environment, in particular the wind directions, would be incomplete.

Fig.8. Wind rose at 10m above ground of the project area.

Fig.9. Wind rose at 30m above ground of the project area.

Given the anomalies, wind engineers in Hong Kong introduces the concept of yawn angle to compensate for this observation. [6] The technique basically observes the shift of wind directions during the wind tunnel test using a Cobra probe measuring devise. Shifts of up to 45 degrees can be detected at various heights. They are then factored into the wind directional components and the synthetic wind roses at different heights can be generated. The representative wind rose can then be evaluated and the most appropriate site wind availability data (speed, direction, probability) can be determined.

Fig.10. Wind rose at 450m above ground of the project area.

4. LAND AND SEA BREEZES Apart from the complex topography of the land, Hong Kong is surrounded on three sides with the sea. Strong land sea breezes effects are experienced (Figure 11). It is therefore necessary to consider not only the seasonal effects of the wind availability, but also the temporal effects of daily changes.

Fig.7. A sheltered urban area of Figure 5 in Hong Kong. The RED circle indicates the project area.

The sea breeze phenomenon is a coupled atmospheric and oceanic response to the differential heating rates of land and water. The onshore directed sea breeze is a mesoscale phenomenon that occurs along coastlines when the land is warmer than the sea due to solar insolation and properties associated with the land-water energy balance. It occurs only when the prevailing synoptic flows are not prohibitively strong (Figure 12). The land sea

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

breeze is a challenging atmospheric phenomenon to characterize because of its relatively small temporal and spatial scale. The sea to land breeze typically peaks at 3pm.

 

 

Fig.11. A schematic understanding of the land and sea breezes.

Strong (l) Moderate (m) Weak (s)

> 8.3 m/s 4.3 – 8.2 m/s 0.1 – 4.2 m/s

Based on the analysis, the hourly wind directions and wind speeds of the HKO stations are extracted and the data are compared to the WGL data. The shifts of the relative wind directions can be noted (Figure 14). The study illustrates an important understanding of “wind for what”. For instance, if conditions under strong wind conditions for safety is under study. It is important to focus on the local wind conditions under strong synoptic winds. Hence the key wind directions of concern would follow mostly the wind direction of the synoptic winds. However, for urban air ventilation, it is the weak wind conditions for human comfort that is of concern, hence one would need to be careful and try to understand the possible wind direction shift as can be demonstrated in Figure 7 (top) especially in the afternoon hot hours.

 

Fig.12. An understanding of the land sea breeze based on an episode of wind conditions on 17 May 2007 in Hong Kong. It can be noted that when the easterly synoptic wind is strong (top left) in the early morning, the wind regime is largely driven by the synoptic winds. However, in the afternoon at 2pm, the sea breeze has on-set, and a convergence zone appears around the western Hong Kong territory (bottom left). This moves slightly eastward in the early evening (bottom right).

 

Fig.13. 10 stations(marked Blue and Orange) have been studied. Hong Kong Observatory stations on the western side of the Hong Kong territory (Orange) shows stronger land and sea breeze effects.

 

Using Hong Kong Observatory station 10 year (Jan 1997 to Dec 2006, n=3650) data, 10 stations around Hong Kong has been studied (Figure 13). The data is extracted based on the following two conditions: Wind directions in the 24 hour period is relatively stable at WGL and from a prevailing direction (e.g. north-east NE or south-west SW) AND Wind speeds in the 24 hour period is relatively stable and fall into 1 of the 3 categories: strong, medium and weak

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Fig.14. When the synoptic wind of WGL, being the Hong Kong’s reference wind station (at the south-east corner of the map in Figure 13) is recording weak North-East winds in the afternoon, a station on the western side of the territory (CPL) is at the same time experiencing South winds.

 

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

case, at this locality, it is important to factor in a consideration of the weak summer wind coming from the South-West despite the prevailing East wind direction.

Fig.15. Under strong synoptic wind conditions, it is noted that CPL’s wind largely follows that of WGL.

 

In addition to the observation understanding, a 24 hour wind simulation taking into account the land and sea breeze effects has been conducted using MM5 (Figure 16).

Fig.16. A 24 hour MM5 simulation is conducted. It shows clearly the land breezes at night and the sea breezes in the afternoon hours.

As such it is important to note the important question: what time is wind most needed. For subtropical summer conditions of Hong Kong, it is opined that for urban human comfort, wind in the afternoon is most needed. Hence, it is more important to factor in the sea breezes than the land breezes. The prevailing directions of the sea breezes of a locality are therefore important to sort out.

5. STRONG VS. WEAK WINDS Apart from the topographical and the temporal understanding, it is important to know the relationship between wind speeds and wind directions. Since the AVA method is a weak wind assessment method. It is important to make sure that under weak wind conditions, the streets are still well ventilated aligning with the prevailing wind directions. As demonstrated in Figure 17. In this

 

Fig.17. A detail analysis of HKO’s wind data shows that the weak wind direction (Bottom) is different from the strong wind direction (Top) in the summer months.

6. DOWNHILL AIR MOVEMENT Hong Kong has a hilly topography. Vegetated hill slopes next to urban areas are known to be beneficial bringing in cool downhill air movement to

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

relief the warmer urban areas. [7] [8] [9] Researches have indicted that the thickness and the air velocity of the downhill movement depends on a number of parameter, as in eqn. 1. [10]

 

Um

(∆θ )½,

∆θ∝R0⅔,

Um/(γ )½

x,

(1)

where Um is the average air movement velocity, ∆θ the potential temperature drop down the slope, γ the sine of the angle of the slope to the horizontal along the streamline, x the downslope distance from the virtual origin of the flow measured along the streamline, and R0 the average net radiation loss on the slope.

 

Based on literature understanding, prudently, for a vegetated or forest slope of 5 to 15 degree, a slope length of a few hundred metres, and a temperature difference of 1-3 degree C, a down slope air movement of around 0.5 to 1 m/s can be expected. The thickness of this gravity flow is not high, around 5 to 20m. Such a flow can easily be dissipated by intercepting building structures and warmer paved surfaces. [11] Nonetheless, when considering urban air ventilation, this is a useful understanding.

7. CONCLUSION The study highlights the importance of understanding the “weak wind” available for design in complex situations. It summarises various understandings – the synoptic winds, the land-sea breezes, the topographically shifted winds, and differences between strong and weak wind conditions, and the downhill air movements – that are necessary for better planning and design decision making. Urban climatologists and wind engineers dealing with air ventilation assessment in Hong Kong is advised to be extra vigilant. Typical methodologies that are typically practised elsewhere in the world may not directly apply.

8. POSTSCRIPT As the paper is drafting, a wind information map is being created for Hong Kong. The purpose is to provide a simple map based understanding for planners to have a better appreciation of the wind environment of Hong Kong in the summer months so that better decisions could be based. The wind information map is part of the on-going urban climatic map studies of Hong Kong. [12].

9. ACKNOWLEDGEMENT Thanks are due HKUST for providing Thanks are also due for providing the 10 analysis.

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to Professor Jimmy Fung of the MM5 wind simulation data. to the Hong Kong Observatory year (1997 to 2006) data for

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10. REFERENCES 1.

Team Clean, 2003: Report on Measures to Improve Environmental Hygiene in Hong Kong, HKSAR. 87. 2. Ng, E., Policies and technical guidelines for urban planning of high-density cities - air ventilation assessment (AVA) of Hong Kong. Building and Environment, (2009). 44(7): p. 1478-1488 3. www.devb.gov.hk/filemanager/en/content_679/hplb-etwbtc-01-06.pdf (assessed Nov 2010) 4. ASCE (1999), American Society of Civil Engineers (ASCE) Manuals and Reports on Engineering Practice No. 67: Wind Tunnel Studies of Buildings and Structures, Virginia. 5. Plate E J (1982), Wind tunnel modeling of wind effects in engineering. In: Plate, EJ (ed.), Engineering Meteorology. Elsevier, Amsterdam, pp. 573-639. 6. Ng, E., Kwok, K. and Hitchcock, P., Wind Tunnel Benchmarking Studies - Batch 1, Urban Climatic Map and Standards for Wind Environment – Feasibility Study, Technical Report for Planning Department HKSAR, Nov 2008. 7. Oke, T. R. (1987). Boundary Layer Climates. London, Routledge. 8. Barlag, A. B., & Kuttler, W. (1990/91). The Significance of Country Breezes for Urban Planning. Energy and Buildings, 15-16, 291-297 9. Weber, S., & Kuttler, W. (2003). Analysis of the nocturnal cold air dynamic and quality of a urban ventilation zone (in German). GefahrstoffeReinhaltung der Luft 63, Nr.9, S. 381-386. 10. Bergen, J.D., 1969: Cold Air Drainage on a Forested Mountain Slope. J. Appl. Meteor., 8, 884–895. 11. Nichol, J. (2005). Remote sensing of urban heat island by day and night. Photogrammetric Engineering and Remote Sensing, 71(5), 613621. 12. www.pland.gov.hk/pland_en/p_study/prog_s/ucmapweb/ (assessed Nov 2010)

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Suburban Neighbourhood Adaptation for a Changing Climate Developing climate change scenarios for suburbs RAJAT GUPTA1, MATTHEW GREGG2 1 2

Low Carbon Building Group, Department of Architecture, Oxford Brookes University, Oxford, United Kingdom Low Carbon Building Group, Department of Architecture, Oxford Brookes University, Oxford, United Kingdom

ABSTRACT: This paper describes the overall aims, methodological framework and key findings from developing climate change scenarios for suburbs, as part of a UK Research Council funded 3-year consortium-based project on ‘Suburban Neighbourhood Adaptation for a Changing Climate’ (SNACC): identifying effective, practical and acceptable means of suburban re-design.’ The paper also evaluates the various techniques available for downscaling temporally and spatially, the recently-released UK Climate Change Projections 2009 (UKCP09) dataset, to conceptualise and quantify the climate change impacts and environmental risks for smaller areas such as neighbourhoods in cities. In order to develop climate change scenarios that are meaningful at the neighbourhood scale, probabilistic climate change data are first analysed and downscaled for three UK cities; Bristol, Oxford and Stockport. For each location, local microclimatic and environmental features, that may exacerbate or ameliorate climate change impacts, are considered for their influence. These local environmental features can range from the city to building scale encompassing neighbourhood influence. The climate change hazards are combined with the neighbourhood and building-level local environmental features to reveal the impacts that need to be addressed in order to test relevant climate change adaptation packages that are effective, practical and acceptable. Keywords: climate change adaptation, neighbourhoods, suburbs, climate change projections

1. INTRODUCTION The overwhelming majority of experts agree that the global climate is changing, and that most of this is caused by human activity, releasing carbon dioxide (CO2) and other greenhouse gases (GHG) into the atmosphere [1]. Since 1900, over 1.7 trillion tonnes of CO2 have been emitted as a result of burning fossil fuels, changes in land use and other human activities, increasing atmospheric concentrations from pre-industrial levels of around 280 parts per million to nearly 390 parts per million today [2]. Even if the most ambitious global mitigation targets are achieved, the world has a 50% chance of warming by 2oC or more by the end of the century [3]. So far the main focus in tackling climate change has rightly been on mitigation, addressing the causes of climate change by reducing greenhouse gas emissions. Mitigation is crucial for avoiding some of the greatest risks in the long term [3]. However, it is likely to take several decades before there is a major reduction in global emissions. Even if all emissions were to stop now, which is of course not feasible, the o Earth is very likely to warm by a further 0.5-1 C over the coming decades in response to historic and current emissions due to the inertia of the climate system [1]. To address these concerns, the UK has made a legal commitment to two kinds of action. On the one hand it is committed to mitigate climate change by reducing greenhouse gas emissions to 80% below 1990 levels by 2050 [3]. On the other it is legally obliged to plan for the climate change that is already

happening and will continue to accelerate, as a result of past, current and future greenhouse gas emissions. This is referred to as adaptation. Adaptation involves responding to the unavoidable consequences of climate change, to which the world is already committed (higher temperatures, changing rainfall patterns, altered seasons, and more extreme weather events). Mitigation and adaptation are not alternatives. Both are essential to reduce the risks to future generations [1]. It is widely accepted that existing built environments are both contributing to, and adapting poorly for, climate change. Buildings and transport account for 75% of energy use in the UK, and our building stock is ill-equipped for either gradual changes in average climatic conditions or extreme events, such as heat waves. Nowhere is this more evident than in the UK's suburbs, which are the most common type of urban area in the UK (and other nations). Suburban areas contain 80% of all homes in the UK, and tend to be characterised by lowmedium density housing that is energy- and landrich, and built-in layouts that encourage car use and discourage walking and cycling [4]. Also, the built environment changes at a rate of about 1% a year, hence the majority of the suburban buildings will still be here in 50-100 years. People are also likely to want to carry on living in suburbs, with almost all attitudinal research showing that suburbs are still the preferred residential location of the majority of households [5]. Hence, for the foreseeable future, the suburbs will be the places where the domestic life of the majority of the population (8/10 people) will be affected most acutely by climate change. Resident’s lifestyles and property will be affected by

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PLEA2011 - 27th International conference e on Passive an nd Low Energy Architecture, A Lo ouvain-la-Neuvee, Belgium, 13-1 15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

gradual cchanges, succh as; hotter, drier summe ers; milder w wetter winters;; decreases in soil moistture content in n summer; an nd by extreme e events such h as and more freq quent high te emperatures, precipitation a wind spee eds [6]. Despiite the urgen ncy of problems facing th ese uburban adap ptation is larg gely absent frrom areas, su both rese earch and po olicy agendas s in the UK [7]. Therefore e, there is an n urgent nee ed to understa and how to a adapt the built environmen nt in suburbs , to ensure th hat they are liiveable and sustainable s in the future. Fa ailure to do so o could have significant hum man, environmental and eco onomic conseq quences [7]. dge ddress this kn nowledge gap p, a cutting-ed To ad research project has been developed. Subur ban urhood Adapta ation for a Changing C Clim mate Neighbou (SNACC)), is a UK Engineering g and Physsical Sciences Research Co ouncil (EPSRC C) funded 3-yyear consortium-based project (worth £6 640,000) with the objective to identify fy effective, practical a and acceptable means of suburban re-de esign in respo onse ojections. SN NACC involvess a to climatte change pro multi-discciplinary team m of academiic partners frrom Oxford Brookes Univerrsity, University of the Wesst of England, and Heriot--Watt Univers sity, as well as stakehold der partners (Bristol ( City, Oxford City a and Stockportt Councils, an nd White Des sign) and exp pert consultan nt, Arup, who can implement the findingss in the built e environment. Both authors form the SNA ACC team from m Oxford Broo okes University y. This p paper describ bes the first work w package e of the SNA ACC project. Using prob babilistic clim mate change p projections, futture climate change c scena arios are develloped, which are meaningful at the city a and suburban n neighbourho ood scale in three UK ccase study citie es. This also provides a us seful example e for other citiies in their endeavour e fo or adapting to o a changing climate. 1.1. Ove erview of SNA ACC project SNAC CC seeks to answer a the qu uestion: How can existing ssuburban neig ghbourhoods be best adap pted to reduce e further imp pacts of climate change a and withstand d ongoing cha anges? The research r focu uses on adapttations to the built enviro onment, thro ugh to individ changes dual homes s and larrger ocioneighbourhood-scale adaptations, using a so e of seleccted approach. A range technical ation strategie es are tested d in neighbourhood adapta erformance (i.e. they pro otect terms of technical pe and property from climate change impa acts people a and mitigate againsst further climate chang ge), practicalitty and accep ptability for the t stakehold ders implemen nting them [8]. Six ne eighbourhoodss from three UK U cities (Brisstol, Oxford an nd Stockport) are used as case studiess. In these arreas, key ag gents of change (e.g. ho ome owners, e elected memb bers and planners) will help p to determine e successful adaptations. a The T project te eam will use m modelling (of climate chang ge, house priices and ada aptation outco omes), tools that allow the participan nts to v visualise what w 'adap pted' neighbourhoods will look like, and a delibera ative methods from social scciences, to generate a portffolio

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of adaptation sttrategies that are feasible, and fully end dorsed by stakeholders. h is divided innto five phases spread The research ove er three years as shown iin figure 1. This T paper des scribes the firrst work packaage (WP1) off Phase 1: En nabling the res search, which is followed by y Phase 2: Da ata collection, Phase 3: Modelling, Phase 4: Testing, and Pha ase 5: Determ mining findings s.

Figure 1: Phas sing diagram off the SNACC res search.

2. Approach of SNACC project: de eveloping 1.2 climate change scenari rios The theoretic cal approach oof the SNACC C project is bas sed on risk analysis. This involves asse essing the haz zards and imp pacts of climaate change, ex xposure of the e case study city and neighbourho oods, and vullnerability of the potentiall occupants, so as to arrrive at robustly-tested (by modelling), te echnicallyfea asible and practical aadaptation measures appropriate for the case studyy neighbourho ood (figure 2).

Figure 2: Risk based annalysis approach h.

In line with this approaach, in the first work ckage of SNA ACC, hazards and impacts of climate pac cha ange are firstt assessed foor the three case c study loc cations, and then appropriaate local enviironmental fea atures and microclimatic facctors are iden ntified that will either ame eliorate or exxacerbate the climate cha ange impacts. To meet the ese objectivess climate cha ange data we ere downloade ed from the usser interface of the UK Climate Projectiions 2009 (U UKCP09) and analysed for each case study s locationn. The data were w then further downscaled via thee UKCP09’s Weather

PLEA2011 - 27th International conference e on Passive an nd Low Energy Architecture, A Lo ouvain-la-Neuvee, Belgium, 13-1 15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Generato or (WG) and cross-refere enced with lo ocal environmental and microclimatic m characteristics c s to assist in tthe selection of specific neighbourhoodss for nvestigation. detailed in

2. UK C CLIMATE PR ROJECTION NS (UKCP09 9) The U UKCP09 provid des publicly accessible clim mate change d data free of ch harge to raise e awareness a and improve ccommunication about climate change and d to assist in n UK adapta ation. UKCP09 is the fifth generatio on of informa ation based on methodol ogy from the M Met Office and d reflects the most m recent, b best insight intto how the climate system works and ho ow it might ch hange in the e future with h built-in log gical uncertainties. UKCP09 9 presents da ata as a resullt of three diffferent possible future climate cha nge scenario levels: low w, medium and a high G GHG 099. The UKCIP02 U is the emissionss up to 20 predecesssor to the more m robust UKCP09, U table e 1 e scenarios presen nted below compares the emissions by both versions [9,10].

Figure 3: Param meters for whichh climate change data is availa able through thee UKCP09 [9].

Beyond re egionally deefined key findings, ind dividually defin ned probabilisstic climate projections p are e available fo or 25km x 255km squares in a grid cov vering the enttire UK [6]. UK KCIP02 also differed in tha at originally the grid resollution for the e UK was 50km2. Figure 4 shows the difffference in res solution for UK K wide key find dings betweenn UKCIP02 (50km2) and UK KCP09 (25km2).

Table 1: IP PCC SRES desiignation of emis ssions scenarioss for UKCIP02 and UKCP09 and corresponding atmosph heric CO2 conceentrations at yeear 2100 [10].

E. Scenario Low Medium-low Medium Medium-high High

 

UKCIIP02 B1 1 B2 2 A2 2 A1F F1

UKCP P09 B1 A1B B A1F1

CO2/pp pm 549 621 717 856 970

2.1. Probabilistic pro ojections d on evidencce, the UKC CP09 providess a Based range of p possible outco omes defined regionally acrross the UK and the probab bilities linked to t each outco me. ely presented by the UKCP P09 Probabilitties most wide are 10%, 50% and 90 0%. 50% is what is referred d to mate’ of prob bability. 10% % is as the ‘central estim and e stated as, ‘very likely to be more than’ a otherwise 90% is o otherwise statted as, ‘very likely to be lless than.’ Fig gure 2 displayys this proba ability range i n a graph ca alled the cumulative distribution funcction (CDF). A As can be se een in figure 2, there is 9 90% probability (it is very liikely) that in this generic ttime ure change will w not incre ase and placce, temperatu more than n 3.7°C [9].

Fig gure 4: An exam mple of represenntation for key fin ndings [11].

As an examp ple of output tthat is availab ble, table 2 below shows the e range of em missions scena arios, time periods and prrobability optiions for North Oxford deffined by a sin ngle 25km gridd square. In addition a to me ean temperatu ure, other clim mate variables s available inc clude mean daily maxi ximum and minimum tem mperature, pre ecipitation ratee, relative hum midity, total clo oud cover, and net surfacee short wave flux. The UK KCP09 also provides p prelim minary key fin ndings for win nd speed to be e refined in thee near future [6,9]. Tab ble 2: Change in n summer meann temp. for Oxfo ord [6].

Oxford O Low emissions 2020 Medium M emissiions 2050 High H emissions s 2080

10% 0.6 1.3 2.6

50% 1.8 3.0 4.9

90% 3.2 5.3 8.1

The SNACC research utillises four future climate periods: 2020s, 2030s, 2040ss and 2050s and three pro obability levels for compaarison: 10%, 50% and 90% % [11]. Figure e 5 shows thee seven overla apping 30yea ar future time periods and hhighlights thos se that are ana alysed for the SNACC projeect. Figure 2: A generic CDF F graph showing g the distribution n of pro obability [9].

2.2. Rep presentation of o data Data for change in climate over land is availa able for the pa arameters presented in figure 3; the orde er of selection toward an outtput can vary. Figure 5: Sev ven 30-year futuure time periods s [11].

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PLEA2011 - 27th International conference e on Passive an nd Low Energy Architecture, A Lo ouvain-la-Neuvee, Belgium, 13-1 15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

3. DOW WNSCALING G UKCP09 DATA D

3.2 2. Temporal downscaling g

The u user interface of o the UKCP0 09 allows the u user to selectt differing fo ormats of re epresentation for extracting g the data attached a to each e 25km g grid square (figure 6). Spatially and temporrally downscalling data with one hin the UKCP P09 can be do through th he use of the Weather Generator (WG). T The data from m the WG ca an then be po ost-processed d to retrieve w weather thresh holds or extrem mes within a d data set via the e threshold de etector.

is necessary for Temporal downscaling qua antifying thre esholds withiin a climate e change dattaset. The UK KCP09 user innterface has a threshold dettector which allows userss to post-pro ocess WG outtputs. Users can create their own thresholds t sim mply by defin ning a periodd of time forr which a we eather variable e exists at a specific mea asurement. So ome pre-define ed thresholds include heating degree day ys (HDD) and d cooling degrree days (CDD). These are e defined as: • HDD: number n of d ays when mean m daily tempera ature is below w 15.5°C; heatting would be requ uired. • CDD: number n of d ays when mean m daily tempera ature is abovve 22°C; coolling would be requ uired [14]. Temporal do ownscaling iss also the method m by wh hich future clim mate data is ttransformed into ‘future we eather years’ which are necessary fo or thermal building modellin ng (e.g. testinng the impactt of future extternal temperatures on thee interior env vironment). There are vario ous methods for downsca aling data (table 3). In th he SNACC pproject, ‘future e weather yea ars’ files are generated th rough a meth hod called ‘tim me series adju ustment’ or ‘m morphing’ which involves ‘sh hifting and strretching’ of oobserved data a to meet pro ojected changes in climate. This process has been use ed to generate ‘future weather years’ from UK KCIP02 data. Alternatively, A ffuture weather years for sellect cities can be developedd using output data from the e Weather Gen nerator [10].

2

Figure 6: 25km grid alignment a over Bristol B [6,12,13]. ].

UKCP P09 absolute climate data can be spatiially and tem mporally dow wnscaled for more deta ailed analysis. This allows seven climate variables (e e.g. mean tem mperature, pre ecipitation (mm m/day), etc.) to o be assessed d at 5km2 grid resolution eitther on a dailyy or hourly ba asis [9]. atial downsca aling 3.1. Spa Down nscaling the geographical resolution frrom 2 o 5km2 doess not provide more clim mate 25km to change data but enable es designers, planners, etc ., to t impact of climate c change e to visually communicate the local autthorities and community stakeholders to implemen nt change in the t built environment for b both adaptatio on and mitigation [12]. nscaling is ussed in the SN NACC projectt to Down spatially divide the citties into 5km m grids by wh hich elected based d on their clim mate neighbourhoods are se change projections in additiion to otther ations. The difference betw ween the clim mate considera data for e each 5km grid d square is in most cases vvery small. Th he most signifficant case is in Bristol whe ere, for example, the differrence betwee en mean mon nthly n and d southwest g precipitation for the northeast grid squares is on ave erage around d 15mm (m most quare) (figure 7 7). precipitation in the soutthwest grid sq

Figure 7: 5km grid squarre alignment ove er Bristol [6,12,1 13].

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Tab ble 3: Options s for temporal downscaling to produce ‘futture weather yea ars’ [10].

Temporal T dow wnscaling met ethods Dynamical D downscaling

Physics-based method m which uses regiona al climate models m to simula ate dynamic proccesses.

Analogue A scen narios

In nterpreting the result of futurre climate cond ditions by us sing other locattions globally thhat have similar (current) cllimate conditions to those projeected for a study y site.

Time T series ad djustment

Stretches and/or shifts higgh resolution (o observed) data to t meet projecteed changes.

baseline

Stochastic S mo odels

Statistical modells utilise relatioonships betwee en climate va ariables to gene erate weather tiime series. The e UKCP09 WG W for example is informed by meteorological rules and ob bserved statistic cal correlations..

3.3 3. Local en nvironmental features

and

micrroclimatic

Increasing the resolution n allows spatiaal res searchers to apply the U UKCP09 data a to more dettailed region nal or locaal environme ental and mic croclimatic information. Loocal features that can eith her ameliorate e or exacerbat ate the impact of climate cha ange on a loc cality include proximity to the coast, ele evation and surroundingg topography, urban density, tree and green sppace coverage, etc. A s vulnerability to floods, forr example, neighbourhood’s o these loccal conditions and is is dependent on ojected to only y be exacerbaated by climatte change. pro As an example of variation bbased on geo ographical

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

location, through the analysis of UKCP09 data for Bristol and surrounding areas, it has been found that 25km grid squares around and over Bristol show an increase in precipitation as they are followed from the east/southeast to the west/northwest (figure 6). Additionally, maximum temperatures tend to be warmer west/southwest of Bristol and cooler to the east of the city [12].

4. CLIMATE CHANGE DATA FOR THE CASE STUDY CITIES In order to choose appropriate neighbourhoods for Bristol Oxford and Stockport, climate change scenarios were defined for each location. Temperature and precipitation data provide the greatest measurable change/impact and therefore are the primary foci to deliver meaningful climate change scenarios for the neighbourhood scale. 4.1. Preliminary analysis In general, the climate change projections for the future reflect the current climate condition for each case study city. As an example, the future projections for the cities and their surrounding regions reflect the current fact that Oxford (southeast England) is generally warmer than Stockport (northeast England). Also, Bristol (west coast of England) receives more annual rainfall than Oxford (southeast England). For the three cities, the high emissions scenarios have the greatest impact on temperature and precipitation. Other climate variables, such as cloud cover and relative humidity for example, tend to be less affected by the variation in emissions scenarios [12]. 4.2. Key climate change findings Overall summer mean temperature increases are projected to be higher than winter mean temperature increases. This difference in temperature change is least noticeable for Stockport. Summer mean temperature increases are projected to be greater in Oxford, however in many instances the change difference between Bristol and Oxford are almost unremarkable. The summer mean temperature increase for Stockport is notably less (Table 4). Generally for the high emissions scenario, central estimate the projected mean summer maximum temperature changes by an approximate 0.5°C increase with every selected time period progression. Table 4: Temperature change comparison between the case study neighbourhoods for 2050s, high emissions scenario, central estimate. The cities are listed in order of magnitude of change [6].

Temperature °C Summer max Summer mean Winter mean

Oxford 3.4 3.3 2.6

Bristol 3.2 3.0 2.2

Stockport 2.9 2.6 2.2

For all locations, the central estimate for annual mean precipitation for all emissions scenarios and all time periods shows little to no change, meaning the offset between increase and decrease are almost equivalent (greater decreases in summer). Summer

and winter mean precipitation changes are projected to be greatest in Bristol. Additionally, for all locations there is a decrease in annual cloud cover and relative humidity (RH) with little to no change in winter cloud cover and RH. The greatest decreases in cloud cover and RH occur in the summer. By 2050s Oxford has the greatest reduction in the mean summer RH, Stockport has the lowest (table 5). Table 5: Precipitation and relative humidity change comparison between the case study neighbourhoods for 2050s, high emissions scenario, central estimate [6].

Precipitation % Annual mean Summer mean Winter mean RH % Annual mean Summer mean Winter mean

Bristol -2 -15 11

Oxford -1 -12 11

Stockport -1 -8 5

-3 -7 0

-3 -7 0

-2 -3 0

5. CLIMATE CHANGE HAZARDS IMPACTS FOR SUBURBS

AND

Once the key climate change hazards have been identified, the impacts and local environmental features (LEF) that may ameliorate or exacerbate these impacts are then defined for each location. As an example, table 6 below shows the hazards, impacts and general LEF for Oxford. The five possible impacts that can be identified for the city of Oxford and its suburbs are overheating, flooding, water stress and construction (material or structural) degradation. Impacts can be both gradual and extreme and may occur as a result of current vulnerability to such existing problems as flooding and water stress (which both exist in Oxford) [15,16]. Oxford, compared to the other cities for example, has the highest percentage of green space cover versus urban built-up areas. This higher percentage of green space has the potential to be beneficial in ameliorating the impacts of specific climate change risks. Table 6: Key climate change hazards and impacts and LEFs for Oxford (high emissions, 2050s) [6,12,15,16]. Hazard Peak summer temp. increase of 3.4°C and mean summer CDD increase of 18-68.

Impact Overheating in buildings leading to possible increased energy use Material degradation

LEF Neighbourhood density; proximity to greenspace, woodland and waterways; proximity to dense urban areas; amount and location of trees and canopy size; building types, heights and material use.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Winter precipitation increase of 11%.

Summer precipitation decrease of -12%.

Flooding and water ingress

Mould growth

urban drainage quality; proximity to greenspace and waterways; ground infiltration capacity.

Water stress and/or drought

Current water stress (high)

Material degradation

Increased imposition of water restrictions and hosepipe bans Subsidence

Soil composition

6. CONCLUSIONS To understand the risk that climate change poses for the suburban typology, findings from the UKCP09 were first extracted and categorised for three case study cities (Oxford, Stockport and Bristol). As current climate change information is available for 2 large areas (at 25km grids), the information needs to be downscaled to be meaningful at the suburban neighbourhood scale. Downscaling of climate change information was found to not significantly increase the detail of the hazard, but is nonetheless relevant for various methods of testing impacts, case study neighbourhood selection and visual dissemination of impacts and risk. Additionally, local environmental and microclimatic features can help to reveal the extent of the climate change impact or possible amelioration of current conditions. Among the three cities, it is realised that Oxford will be most impacted by summer heat increase and Bristol is expected to see the greatest reduction in summer precipitation. Once the hazards are defined and related to relevant LEFs, the impacts for both the neighbourhood and building scale can be described, so that appropriate adaptation packages can be identified and tested to be technically-appropriate, practically-feasible and acceptable.

7. ACKNOWLEDGEMENTS The authors gratefully acknowledge the support of the Engineering and Physical Science Research Council (EPSRC) for financially supporting the SNACC project, under Grant reference: EP/G060959/. SNACC project is funded under the Living with Environmental Change Programme (LWEC) and is part of the Adaptation and Resilience to a Changing Climate (ARCC) Coordination Network.

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REFERENCES [1] IPCC (2007). Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, Pachauri, R.K and Reisinger, A.(eds.)]. Geneva: IPCC. [2] http://www.esrl.noaa.gov/gmd/ccgg/trends (Accessed: 1 November 2010). [3] Adaptation Sub-Committee (2010). How well prepared is the UK for climate change? First report of the Adaptation Sub-Committee, London: Committee on Climate Change Adaptation. [4] House of Commons: Communities and Local Gov. Committee (2008). Existing housing and climate change: Seventh report of session 200708. London: The Stationary Office Ltd. [5] Williams K (2007) New and Sustainable Communities in the UK, A Report for the Cultural and Educational Section of the British Embassy. [6] http://ukclimateprojections.defra.gov.uk/ (Accessed: 1 December 2010). [7] Johar I and Maguire C (2007) Sustaining our Suburbs, a Report for RICS and CABE, RICS, London. [8] Williams, K. Joynt, JLR and Hopkins, D. (2010). ‘Climate change and the compact city: the challenge of adapting suburbs’, Built Environment, 36 (1), 105-115. [9] Jenkins, G. J., et al. (2009). UK Climate Projections: Briefing report. Exeter: Met Office Hadley [Online]. Available at: http://ukclimateprojections.defra.gov.uk/images/s tories/briefing_pdfs/UKCP09_Briefing.pdf (Accessed: 23 September 2010). [10] CIBSE (2009). Use of climate change scenarios for building simulation: the CIBSE future weather years. TM48: 2009. London: CIBSE. [11] Murphy, J.M., et al. (2009), UK Climate Projections Science Report: Climate change projections. Exeter: Met Office Hadley [Online]. Available at: http://ukclimateprojections.defra.gov.uk/images/s tories/projections_pdfs/UKCP09_Projections_V2 .pdf (Accessed: 23 September 2010). [12] ARUP (2010a). SNACC: Report for work packages 1.1 and 1.2. London: ARUP. [13] http://maps.google.co.uk/ [14] BADC and UKCIP (2010). The UKCP09 threshold detector manual: Version 1.1.0. [Online]. Available at: http://ukclimateprojectionsui.defra.gov.uk/ui/docs/td/td_manual.pdf (Accessed: 26 October 2010). [15] http://www.environmentagency.gov.uk/homeandleisure/floods/default.as px (Accessed: 23 September 2010). [16] http://www.oxfordtimes.co.uk/news/705598.Hose pipe_ban_in_force_from_April/ (Accessed: 1 November 2010).

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Urban morphology and temperature mapping comparative study Case study: Singapore's commercial area Nyuk Hien Wong1 , Steve Kardinal Jusuf 2 , Rosita Samsudin3 , Marcel Ignatius4 1,4

2,3

Department of Building, National University of Singapore, Singapore Centre for Sustainable Asian Cities, National University of Singapore, Singapore

ABSTRACT: Extensive urban development in high density cities may lead to increasing of urban air temperature and heat island index. Urban morphology parameters of canyon geometry, sky view factor (SVF), surface material reflectivity (albedo) and greenery affect air temperature generated within urban canyon, besides the initial role of local climate condition. Singapore is an example of high density city in hot humid climate region which experiences extensive urban development with many high rise buildings are constructed due to the limited land area. This comparative study investigates the effects of low rise and high rise developments' urban morphology towards air temperature generated in Singapore's commercial area by implementing an air temperature prediction model. Geographic Information System (GIS) platform is utilized to generate a temperature map which is used for detail analysis. Keywords: urban morphology, urban temperature mapping, high density urban area, Singapore's commercial area

1. INTRODUCTION Increasing urban air temperature is happening in most world's developed and high density cities. This leads to urban heat island (UHI) issue and affects urban environment quality. The major causes include diminishing of greenery area, low wind velocity due to high building density and change of surface coating materials [1]. UHI effect is dependently affected by canyon geometry, building materials, greenhouse effect, anthropogenic heat, evaporation and wind flow [2]. As the most developed country within Southeast Asian region with rapid population growth, strong economic growth and stability, Singapore has experienced extensive urban development for the past decades. The main economic activities are majority located within high rise office and commercial buildings, concentrated within Downtown Core area. Earlier study on Singapore UHI indicates that UHI effect is seen during daytime from the satellite image. Commercial area is one of the areas, besides airport and industrial areas, that is observed to become the 'hot' spot. The satellite image also shows some 'cool' spots, which are mostly observed on the large parks, the landscape in-between the housing estates and the catchment area [3].

As response to high demand of commercial spaces despite of limited land space, current Singapore's commercial area urban planning allows high rise developments with plot ratio ranging from 5 to more than 11.2. It is translated to allowable building height ranging from 25 to more than 50 storeys height with some exceptions are applicable for some historical sites for conservation purposes. Presence of densely built high rise buildings may confirm the possibility of UHI existence as what has been mentioned in the earlier studies. During daytime, high rise buildings benefit urban area by providing shading and reduce urban area sky openness, resulting the possibility of lower air temperature generated. However during night-time, the heat absorbed by buildings' surface material is released into and trapped within the urban canyon because of the limited sky openness, resulting the possibility of higher air temperature generated. Earlier study on Singapore's UHI profile as shown in Figure 1, identifies commercial area with lower air temperature during daytime and higher air temperature during night-time [5]. The aim of this study is to investigate the relation between urban morphology and greenery with air temperature, to give inputs for future urban planning in improving urban environment quality for high density urban area development.

Geographically Singapore is located between o o latitudes 1 09' North and 1 29' South, longitudes o o 103 36' East and 104 25' East. Based on metrological data from Singapore National Environmental Agency (NEA), Singapore can be classified as a region with hot humid climate. Uniform high temperatures, humidity and rainfall throughout the year characterize this climate [4].

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radiation is used in Tmax models. SOLAR predicted is not applicable for Tmin models. •

Urban morphology predictors: percentage ratio of pavement area and surface area within 50 meter radius buffer (PAVE), average building height to building area ratio within 50 meter radius buffer (HBDG), total wall surface area within 50 meter radius buffer (WALL), Green Plot Ratio (GnPR) within 50 meter radius buffer, sky view factor (SVF) and average surface albedo (ALB).

3. CASE STUDY The extent of commercial areas observed in this comparative study is limited to area as shown in Figure 2. The closer analysis will focus on group area 1 and group area 2 as highlighted. The categorization is based on their urban geometry characteristics. Group area 1 is a densely built low rise commercial area with average building height of 15.9 meter comprises of shop-houses which is maintained as a conservation area. Group area 2 is a densely built high rise buildings which has uniformity in height with average building height of 144.7 meter. Both area 1 and 2 have site coverage ratio of 0.65.

Area 1

Area 2

Figure 1: Urban Heat Island (UHI) profile in Singapore

2. METHODOLOGY Geographic Information System (GIS) platform is utilized in this study to capture climatic and urban morphology parameters. Urban climatic mapping method has become widely used for urban planning as it can provide a clear picture from the regional scale of 1:100,000 to the urban scale of 1:5,000. And by using GIS, in this study context, temperature map can be developed together with analysis on different information layers. The methodology also follows the air temperature prediction model STEVE (Screening Tool for Estate Environment Evaluation) developed by Jusuf et al. [6], which is designed for wind calm condition and represents Singapore's condition. Temperature maps of predicted Tmin (minimum temperature), Tavg (average temperature) and Tmax (maximum temperature) are built up by total of 140 measurement points, each is positioned within 50 meter radius buffer. The measurement points are distributed at pedestrian level of 2 meter high throughout studied commercial areas. The predicted temperatures are governed by some independent predictors as following: •

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Climate predictors: RefTmin, RefTavg and RefTmax at measurement point, daily solar radiation (SOLAR). Average daily solar radiation is used in Tavg models and maximum solar

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Figure 2: Area 1 and 2 selected as sample area for comparative study

4. FINDINGS By considering climate and urban morphology predictors, predicted air temperature Tmin, Tavg and Tmax are inserted as GIS layers to generate a temperature map that can be analysed in detail based on some urban determining variables of canyon geometry and green plot ratio (GnPR). 4.1. Canyon geometry Discussion on canyon geometry includes building height and surface area variables. The observations on canyon geometry and predicted Tmax of group area 1 and group area 2 are shown in Table 1 and 2.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 1: Canyon geometry observation and predicted Tmax of group area 1.

MP 66 67 68 78 79 80 81 90 91 92 93 94 104 105 106 107

AV-HT 27.3 12.2 23.4 11.8 10.1 11.3 24.3 12.6 29 8.2 10.6 19.4 18.7 10.3 11.7 10.8

WALL 8368.5 2957.3 8532.1 7668.6 6097.6 7367.6 12400.6 5347.3 14970 4927.3 9495.1 12772 4912.1 6872.6 7677.3 4618.6

SVF 0.4 0.6 0.4 0.3 0.4 0.3 0.5 0.4 0.3 0.3 0.2 0.3 0.5 0.3 0.3 0.4

Tmax 31.9 32.3 31.9 31.7 31.8 31.8 31.7 32 31.7 31.6 31.6 31.7 32 31.8 31.7 31.9

Figure 3: Plotted graph on relation between wall surface area and Tmax for group area 1

Table 2: Canyon geometry observation and predicted Tmax of group area 2.

MP 60 61 72 73 74 85 86 87 97 98 99 100 110 111 112 123 124 125

AV-HT 47.9 30.8 44.6 33.7 13 44.9 52.2 109.2 32.4 53.1 78.9 79.6 147.8 105.1 74.4 54.4 72.7 24.4

WALL 22313.8 8317.7 21016.9 26843.2 2646.5 19491.2 34912.5 36075.9 5422 19658.9 36765 17985 41796.7 43155.8 24796 17850.4 21918.1 3328

SVF 0.3 0.3 0.1 0.2 0.5 0.2 0.2 0.2 0.4 0.2 0.2 0.6 0.4 0.2 0.3 0.5 0.3 0.6

Tmax 31.8 31.9 31.6 31.8 32.1 31.7 31.8 31.8 31.9 31.8 31.9 32.2 32.1 31.9 32 32.2 31.9 32.1

From plotted graph shown in Figure 3, 4 and 5; it is found that there is relation between wall surface area and SVF with temperature generated within urban canyon. Higher value of wall surface area will reduce Tmax as effect of building shading that falls onto urban canyon. However, heat that is absorbed by building surface material during daytime, will be released into urban canyon during night-time. The heat that is trapped within the urban canyon due to sky openness obstruction, will affect in increasing Tavg and Tmin. SVF value is influenced by urban geometry and greeneries. Therefore higher SVF value will increase amount of solar radiation coming into the canyon and affects Tmax and Tavg. On the other hand, it is noticed that building height does not seem to have noticeable effect towards urban air temperature change as shown in Figure 6 and 7. It is building height proportions over urban corridor width that determines the SVF value and later affect the air temperature generated within urban canyon.

Figure 4: Plotted graph on relation between wall surface area and Tmax for group area 2

Figure 5: Plotted graph on relation between SVF and Tmax for group area 1 and group area 2

Figure 6: Plotted graph on relation between average building height and Tmax for group area 1

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Figure 7: Plotted graph on relation between average building height and Tmax for group area 2

Figure 8: Plotted graph on relation between GnPR and TAvg

4.2. Green plot ratio (GnPR)

5. TEMPERATURE MAP

Green plot ratio (GnPR) is a three dimensional measurement of green volume by dividing sum of total leaf area by the site area. Tree with large shading leaves governs to higher value of GnPR and reduce the degree of urban area sky openness (SVF value). Thus it will help to reduce urban air temperature generated. Table 3 below shows the observation of greeneries provision found in studied areas and predicted TAvg findings.

Predicted air temperature of TMax, TAvg and Tmin are inserted as layers in GIS together with urban morphology layers. The detail analysis of temperature map for group area 1 and group area 2 are elaborated in sections below. 5.1. Group area 1

Plotted GnPR and predicted TAvg values as drawn in Figure 8 confirms the effect of greenery towards urban air temperature. The higher GnPR value, the lower air temperature generated. Table 3: GnPR observation and predicted Tavg of group area 1 and group area 2.

Group area 1 MP 66 67 68 78 79 80 81 90 91 92 93 94 104 105 106 107

GnPR 1.22 1 1 0.97 1 1.04 0.62 1 1.25 1.12 0.12 0.03 1.47 1.16 2.1 1.3

Group area 2 TAvg 28.5 28.8 28.4 28.4 28.4 28.5 28.5 28.5 28.3 28.3 28.4 28.4 28.4 28.5 28.3 28.4

MP 60 61 72 73 74 85 86 87 97 98 99 100 110 111 112 123 124 125

GnPR 1.32 1.42 1.41 1.45 1.37 0.4 0.1 0.92 1.17 1.14 0.73 0.97 1.75 1.41 1.5 1.06 1.45 1.93

TAvg 28.7 28.7 28.4 28.7 28.5 28.5 28.7 28.8 28.4 28.6 28.9 28.6 28.8 28.8 28.8 28.8 28.7 28.5

(a)Tmax

(b)Tavg

(c) Tmin Figure 9: Temperature map of group area 1

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Temperature maps of Tmax, Tavg and Tmin generated for group area 1 as drawn in Figure 9 show that in general during daytime the air temperature within urban canyon is rather uniform throughout with some ‘hot’ spots are noticeable around the road junction and surrounding open space. It is found that there is less provision of greeneries and other shading variables around those 'hot' spots. This condition potentially increases the urban area sky openness (SVF) which results in higher air temperature generated. Temperature map Tmax shows the presence of lower air temperature along the shop-houses' urban corridor. Densely built shop-houses along 11 meter width urban corridor potentially contributes in lowering SVF value at the centre of group area 1. On the contrary, temperature map Tmin shows the presence of higher temperature within shophouses' urban corridor compared to surrounding open space. It confirms that UHI effect exists within this area. 5.2. Group area 2

Temperature maps of Tmax, Tavg and Tmin generated for group area 2 as drawn in Figure 10 show that during daytime air temperature within urban canyon seems to be lower compared to air temperature generated during night-time. It confirms the presence of UHI effect within group area 2. Tavg map shows that ‘hot’ spots are generally concentrated at the centre of group area 2 which comprises of high rise buildings with height varies from 25 to 190 meter. The average urban corridor width measured shows value of 33 meter. The highest temperature is noticed to be present around the open space where there is less provision of trees and other shading variables. By comparing temperature maps of group area 1 and group area 2, it is also found that air temperature generated within group area 1 is lower compared to group area 2 during daytime and night-time. Higher night-time air temperature of group area 2 is caused by the higher wall surface area as result of high rise buildings which potentially absorb and release more heat into urban canyon. Regardless the building heights that potentially benefit by providing shading onto urban area, the optimum proportion between buildings height over urban corridor width and greenery provisions determines urban area sky openness and affects the air temperature generated within urban canyon. It can be seen from Figure 5 above where group area 2 has actually higher SVF value compared to group area 1.

6. CONCLUSIONS

(a)Tmax

Urban morphology parameters of urban geometry, surface material and sky view factor determine the urban air temperature generated within urban canyon. Study from Singapore's commercial group area 1 and group area 2 confirm the hypothesis of UHI presence within high density urban area regardless low and high rise building developments. However, greenery provision of tress with large canopy and dense leaves seems to help in reducing the air temperature generated, benefit from their shading potential.

(b)Tavg

(c) Tmin Figure 10: Temperature map of group area 2

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7. REFERENCES [1] K. Takahashi, H. Yoshida, Y. Tanaka, N. Aotake and F. Wang. Measurement of Themal Environment in Kyoto City and Its Prediction by CFD Simulation, Energy and Buildings 16 (2004), 771-779. [2] M. Santamouris. The Canyon Effect. Energy and climate in the urban built environment, London (2001). [3] N. Y. Wong. Study of Rooftop Gardens in Singapore, Singapore (2002). [4] www.nea.gov.sg [5] S.K. Jusuf, et al. The influence of land use and the urban heat island in Singapore. Habitat International 31 (2007), 232-242. [6] S. K. Jusuf and N. Y. Wong. STEVE tool: A web application of Singapore air temperature prediction model. Accepted for publication in Journal of Green Building.

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Trees and heat fluxes: how much do they contribute to the energy balance at urban spaces? Loyde Vieira de ABREU1, Lucila Chebel LABAKI1 1

School of Civil Engineering, University of Campinas, Campinas, Brazil

ABSTRACT: Results of local-scale surface energy balance observations reveal that latent heat fluxes, Qe, provided by trees are important in the surface energy control of cities. Arboreal species provide different storage latent heat, a characteristic related with the mitigation of air temperature in local-scale provided by them. The aim of this work is to compare heat fluxes in different arboreal species along the day and verify their contribution for thermal comfort inside and outside buildings. The required data are: net radiation flux density retained by 2 sunlit and shaded layers (W/m ) (collected by tube solarimeters), air temperature and relative humidity, atmospheric pressure and vegetation phenology (size of crown, leaves and foliar area). The measurements were carried out during the day, from sunrise to sunset, in three-day periods, throughout the year, covering different seasons. The energy balance scheme is based in the big-leaf model by Penman-Monteith (FAO056). In the research four tree species were analyzed, chosen from the most used trees in urban forestry in the South2 East region of Brazil. Results showed that Qe by each trees varied between  and W.h/m during the year. The greatest contribution of trees for the energy balance was observed in the afternoon period. The different results obtained were due to the characteristics of the sample individual, such as structure and density of the treetop, size, shape and color of leaves, tree age and growth stage. Trees with higher tops have a good contribution in the cities, due to their energy consumption and higher solar radiation attenuation. Deciduous species are excellent in sub-tropical climate, because they can reduce heat fluxes in summer and allow them in winter. The trees around building, on streets and parks can reduce air temperature, by diminishing the conductive and convective heat gains. This effect provides thermal comfort and can reduce the energy for cooling of the buildings. These characteristics of vegetation should be taken in account by professionals of the urban built environment to improve thermal comfort outdoors, reducing the effect of heat island so ensuring better quality of life for people. Keywords: thermal comfort, heat flux, solar radiation.

1. INTRODUCTION One of the main causes of cities climatic changes is due to the accelerated expansion of urban centers, where green areas are generally occupied with construction and buildings. It occurs due to thermal characteristics of different kinds of surfaces present in urban spaces and due to their behaviour with respect to the incident solar radiation represents serious impacts on the equilibrium of the environment [1]. These impacts lead to undesirable consequences, reducing thermal comfort and increasing the potential of health impairment of urban populations. By observing the importance of vegetation in the control of the incident solar radiation and as a regulator of the urban climatic changes, it becomes meaningful to qualify and quantify how the vegetation influences on environmental parameters such as air temperatures and relative humidity [2]. This knowledge permits to obtain guidelines for the elaboration of plans and projects aiming to improvement of urban thermal comfort. Several authors have pointed out the benefits of vegetation in improving city climate like Oke [1], Matzarakis [3] and Gulyás [4] . Bueno-Bartholomei [5] evaluated the attenuation of solar radiation by different isolated tree species, showing that this attenuation is due to specific characteristics of the analyzed species and to individual sample characteristics like structure and density of the

treetop, size, shape and colour of the leaves, tree age and stage of growth. Grimmond et al. [6] observed that the water evaporation on the surface of leaves mitigates air temperatures, due to the loss of latent heat. The so called evapotranspiration, an indirect process, includes two biophysical phenomena: the water evaporation of the soil and the transpiration, loss of water in the tree leaves [2]. Kjelgren and Montague [7] studied the transpiration of tree species as affected by energybalance propriety of paved and vegetated surface. The results show that isolate trees over paved asphalt surface intercept more long-wave radiation. Trees responses to increased energy loading will vary with species, humidity of atmosphere, and how much of the crown is exposed. Species from hot or arid habitats either tolerant to high temperatures or able to dissipate heat with small leaves, would less likely be affected by energy radiated from a paved surface. Broadleaf deciduous species originating from temperate forests, such as maple and pear, however, are commonly planted in urban area. Longwave energy interception from an asphalt surface is more likely to trigger a feed-forward response in these species which results in prolonged stomata closure. Clustering of trees and increased crown density result in lower foliage exposed intercepting long-wave radiation, because if a great percentage of foliage would not be exposed, the attenuation of solar radiation could affect by increasing energy loading.

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The aim of this study is the evaluation of the influence of heat fluxes provided by different arboreal species in the energy balance at urban spaces, through the measurements of environmental parameters.

2. METHODS The measurements were carried out during three sunny days in two seasons (summer and winter) in four trees from 2007 to 2010. This research was realized in Campinas, Brazil, located at 22 ° 48'57 "S, 47 ° 03'33" W and at altitude 640 m. The city's climate is classified as tropical of altitude, with mean annual air temperature 22.3 º C, annual rainfall 1411 mm, with the predominance of rain in the months from November to March and dry periods of 30 to 60 days during July and August. In this research, the microclimatic and instantaneous scales are adopted. This choice of scales allows analyzing in loco the degree of influence through mitigation of air temperature and solar radiation incident on individuals of trees. 2.1. Species and sites selection The criteria for the choice of species were those most used in tree planting programs by the city government in Campinas, Brazil. The trees should fulfill such conditions as: to be adult in age, to have representative physical characteristics of the species, and to be located in areas with the adequate conditions for measurements: no shading by other trees or buildings; topography of the ground around the species; accessible area for the measurement equipment; no interference of other people; uniformity of conditions around the trees. The trees studied were localized at the University Campus and Rio das Pedras Farm (figure 1).

In leaf

Sibipiruna (Caesalpinia peltophoroides)

in leafless in flowers Ipê-Amarelo (Tabebuia chrysotricha)

Jambolão (Syzygium cumini)

Mangueira (Mangifera indica)

Figure 2: Individual arboreal analyzed

2.2. Equipment and analyses methods The radiation balance was measured using two sets of tube solarimeters, type TSL (Delta-T Devices). Sensors from the tube solarimeters were connected to a logger, model DL2, also from Delta – T (figure 3 e 4).

Figure 3: Tube solarimeters, Delta-T TSL

LEGEND 1-Syzygium cumini (Jambolão) 2-Mangifera indica (Mangueira) 3-Tabebuia chrysotricha (Ipê-Amarelo) 4-Caesalpinia peltophoroides (Sibipiruna) Figure 1: Species localization

Four arboreal individuals were selected: IpêAmarelo (Tabebuia chrysotricha) – deciduous –, Jambolão (Syzygium cumini L.) – perennial -, Mangueira (Mangifera indica) – perennial - and Sibipiruna (Caesalpinia peltophoroides) – semi deciduous (figure 2).

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One set of equipment was installed at the middle of the tree shadow, while the second one was installed at sun, figure 4. Data were collected beneath crowns of studied trees and in the open simultaneously. Measurements started at about 6:00 a.m. and finished at about 6:00 p.m. and were recorded each ten minutes. This equipment measures average irradiance (W/m2) in situations where the distribution of radiant energy is not uniform, such as beneath tree crowns and greenhouses. The spectral response corresponds to visible and near infrared radiation (350 nm to 2500 nm). So, the wave radiation absorbed by trees (Rnc/LA) in a period of time can be computed by:

R nc / LA =

Rn sun - Rn Rn sun

sh

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Where Rsun is solar radiation measured by tube 2 solarimeter in sun (Kwh/m ), Rsh is solar radiation measured by tube solarimeter in tree canopy 2 (Kwh/m ).

figure 6. All recording sets were protected from solar radiation through especially prepared shelters for outdoors measurements and data were collected each 10 minutes, in 12 hours throughout the day. Based on data collected - net radiation, air temperature, relative humidity and wind –, it was calculated the transpiration rate by the PenmanMontheit (FAO-56) method [8] [9]: λE = ALA[(∇ Rnc/LA + 600 ρ cp ea /ra) / (∇+γ(2+rss,sh/ra)]

Figure 4: Tripod and solarimeters positioned at the tree

For the collection of the data of the environmental parameters (air temperature, relative humidity, globe temperature) sensors were fixed to a tripod at different distances to the trunk (in the shadow and in the sun), figure 5. In each set there was one temperature and humidity recorder, model Testo 175-1; and a globe temperature recorder, model Testo 175-T2, connected to a temperature sensor, placed in the interior of the globe (figure 5).

where ALA is leaf area, λ is the latent heat of 2 vaporization (J/g), E is the transpiration rate, (g/(sm per unit leaf area), Rnc/LA is the net radiation flux density retained by sunlit and shaded layers (W/m2), respectively, ea is the canopy - level vapour pressure deficit of air (Pa), ra is the total tree leaf boundary 2 layer resistance (s/m ) to vapour and heat s,sh are movement, which are assumed equivalent, rs the average leaf stomatal resistances (s/m) for the sunlit and shaded layers, ∇ is the slope of the saturation vapour pressure curve, (Pa/C), at Ta, γ is the psychrometric constant (66.2 Pa/C), ρ is the 3 density of air (g/m ), and cp is the specific heat capacity of air at constant pressure, (J/(g C)). The variables rs, (1/gs), and ea can be measured directly, while ra is proposed to be calculated using the following empirical formula by Landsberg and Powell [10]: ra = 58 p

0.56

(d/u)

0.5

where d is the leaf characteristic dimension, u is the canopy - level wind speed, and p is a dimensionless number derived from the ratio of total to crown silhouette area perpendicular to horizontal wind flow, by Kjelgren and Montague [7]. The leaf characteristic dimension was calculated by the method of Marin and Angelocci [11]. Table 01 shows the results of ρ e δ for the evaluated trees. Table 01: Value de ρ e δ from trees evaluated. Arboreal Species

Figure 5: Tripod with the settled protections

   

ALA 2 (m )    

      

ρ    

δ    

Leaf area index (LAI) of each analyzed tree was determined by Tsutsumi et al. [12] method, based on eye-fish pictures obtained by Zigma lens 4,5mm. The mean value of LA was obtained by the arithmetic average of LA determined by canopy analyzed based on project canopy area on soil surface. In order to investigate the energy contribution by different arboreal species, the energy balance can be estimated by: Rn =Qe + QH + Qg + Qps

Figure 6: Tripod with anemometer

Wind speed data were collected in one fixed site with Testo anemometer, model 0635-1549, connected to a multifunction recorder, model 445,

where Rn is net radiation, Qe is Latent Heat flux, QH is Sensible heat flux, Qg is Soil Heat flux. Qps is the flux due to photosynthesis. The values of Latent heat (QL) is based on tree transpiration rate (λE); and, Qg and Qps represent 10% from Rn.

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Table 3: Transpiration daily during the year

3. RESULTS Figures 7 and 8 illustrate the results for solar radiation by each species at shadow and sun, in summer and in winter, respectively. SOLAR RADIATION ATTENUATED: SUMMER Sun Jambolão (Syzygium cumini) Sibipiruna (Caesalpinia peltophoroides)

Ipê-Amarelo (Tabebuia Chrysotricha) Mangueira (Manguifera indica)

0.8 0.7

KW/m2

0.6 0.5

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CLIMATIC, WATER AND BIODIVERSITY CONTEXT

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Figures 11 to 14 bring energy balance components - Latent Heat flux (Qe), Sensible heat flux (QH), Net Radiation (Rn) less Soil heat flow (Qg) – during the day in summer. Figures 15 to 19 show the energy balance during the day in winter. Ipê-amarelo (Tabebuia chrysotricha) shows the smallest quantities for latent-heat (Qe) in summer, 2 2 394.25 W/m , and in winter, 116,68 W/m . Consequently, this species has less capacity of environment cooling than others during the year. As well, Sibipiruna (Caesalpinia peltophoroides) obtains the best results for transpiration during the year.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Energy Balance Ipe Amarelo (Tabebuia chrisotricha) in leafless : winter

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Figure 16: Energy Balance – Ipê-amarelo (Tabebuia chrysotricha) in flowers Energy Balance Jambolão (Syzygium cumini ) - winter

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6. REFERENCES

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4. CONCLUSION The results confirm that trees have the greatest contribution in controlling the heat fluxes in cities, however it is necessary tree management strategy. It is shown that the tree characteristics like structure and density of the treetop, size, shape and color of leaves, tree age and growth, may manipulate the tree performance in microclimate. For example, species with dense and low canopy and large leaves, such as Jambolão (Syzygium cumini) and Mangueira (Manguifera indica) show similar data for solar radiation attenuation and transpiration rate during the year, while deciduous species, like Ipê-amarelo (Tabebuia chrysotricha), present some differences along the year. As well, species like Sibipiruna (Caesalpinia peltophoroides) with little leafs and plagiotrophycal branch, present the best contribution to control the heat fluxes during the year. This tree can mitigate air temperature in summer and humidify the air in winter, in addition, it had the best capacity of absorbing latent-heat, and controlling the solar energy. This happens due to the fact that the structure of the crown hinders the ventilation according to the ascending movement of hot air. In addition, the energy balance estimatives by different species arboreal are important data for sustainable urban planning, because trees contribute to create lower temperature spaces, improve the thermal comfort and can save energy. Besides, trees could be used to shade building, allowing thermal comfort in outdoor and indoor places. The solar radiation intercepted by the crown functions as a natural protection in outdoor spaces, mitigating temperatures and reducing the energy spent on cooling indoor spaces. The evaluation of different arborous species commonly found in the urbanization of cities is an important information for urban planning aiming to requalify the urban microclimate. In addition, treeplanting is a practical and inexpensive solution, and is considered an energy-efficient alternative.

5. ACKNOWLEDGEMENTS This work was sponsored by FAPESP/Fundação de Amparo à Pesquisa do Estado de São Paulo (Research Support Foundation of São Paulo State).

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[1] Oke T.R. (1987); 'Boundary Layer Climates', Second Edition, Routledge, [2] Santamouris, M. (2001); Energy and climate in the urban built. Londres: James & James, 402 p. [3] Matzarakis, A.; Rutz, F.; Mayer, H. (2007); Modelling radiation fluxes in simple and complex environments – application of the Rayman model. International Journal of Biometeorology n.51, 323-334. [4] Gulyás, Á.; Unger, J.; Matzarakis, A. (2006); Assessment of the microclimatic and thermal comfort conditions in a complex urban environment: modeling and measurements. Building and Environment, 2006, v. 41, p. 17131722. [5] Bueno-Bartholomei, C. L. (2003). Influencia da vegetação no conforto térmico urbano e no ambiente construído. Campinas, SP, Tese (Doutorado). [6] Grimmond, C. S. B.; Oke, T. R.; Steyn, D. G.; (1986); Urban water balance: a model for daily totals. Water Resources Research; v. 22, p. 1397-1403. [7] Kjelgren R. and Montague, T. (1998); Urban Tree Transpiration over Turf and Asphalt Surfaces, Atmospheric Environment, 32, 1, 3541. [8] Penman, H.L. (1956); Evaporation: an Introductory Survey. Neth. J. Agric. Sci, n. 4, p.9-29. [9] Monteith, J. L. (1965); Evaporation and environment. Symp. Soc. Expl. Biol., n. 19, p. 205 – 234. [10] Landsberg, J. and Powell, D. (1973); Surface exchange characteristics of leaves subject to mutual interference. Agricultural Meteorology, v. 13, p. 169-184. [11] Marin, F. R. ; Angelocci, L. R.; Vila-Nova, N. A. (2003); Estimativa da transpiração máxima de lima ácida ´Tahiti´ pelo modelo de PenmanMonteith. Revista Brasileira de Agrometeorologia, Santa Maria/RS, v. 11, n. 2, p. 237-243. [12] Tsutsumi, J. G.; Ishii, A.; Katayama, T. (2003); Quantity of plants and its effect on local air temperature in an urban area. In: ICUC5 2003 (FIFTH INTERNATIONAL CONFERENCE ON URBAN CLIMATE,1-5), 5., Lotz, Polland. Proceedings.... Lodz, Poland: ICUC, 2006. Available at:

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Forecasting carbon emissions of the UAE residential sector—a case study of Abu Dhabi Hassan RADHI1, Steve SHARPLES 2 1

Architectural Engineering Department, UAE University, United Arab Emirates 2 School of Architecture, University of Liverpool, Liverpool, United Kingdom

ABSTRACT: This study forecasts transformations in carbon emissions from the UAE residential sector. It introduces a regional bottom-up model for assessing CO2 emissions. Archetypes were first developed and simulation models then used. The outcome provided the basis for developing a statistical bottom-up model for the housing stock. This model explores the ways in which CO2 emission levels are affected by global warming and how such levels can be reduced through the use of different building energy efficiency measures. Abu Dhabi emirate was taken as a case study. The results demonstrated the capability of the developed model in forecasting the future trends of CO 2 emissions in the UAE residential sector. It was shown that improving building energy efficiency can generate considerable carbon emissions reduction credits at a competitive cost. Keywords: Forecasting carbon emissions, residential sector, UAE

1. INTRODUCTION By signing up to the Kyoto Protocol, the UAE is required to play a very active role in conserving energy, protecting the environment and reducing greenhouse gases, particularly CO2 emissions. Protecting the depleted energy and reducing its impact on the environment would have a number of benefits for the UAE, such as increasing the exported fossil fuels and limiting the impact of global warming. Based on this, considerable sustainable developments and global warming initiatives have been made in the UAE. A number of economic development programmes have been planned and dedicated to establishing new economic sectors focused on alternative energy and sustainable technologies. Two huge and costly projects are planned to be completed in the next few years: first, a $350 million solar power plant and, second, a $2 billion hydrogen-fuelled power plant. Clean and renewable energy has also been utilised in establishing low energy and zero carbon emission buildings as can be seen in the Masdar City initiative. Another initiative is the implementation of new building energy codes which conform to the most demanding global standards. These codes were developed on the basis that such a program can reduce the total energy consumption and consequently the CO2 emissions. Forecasting future trends in CO 2 emissions has been a growing concern in recent years. A great deal of effort has been spent to model current and future trends of energy consumption and its associated CO2 emissions. Some studies have explored the impact of increasing CO2 emissions and global warming on heating and cooling energy use in building sector [13]. Other studies have investigated how likely the global warming can contribute to energy use and its associated CO2 savings [4]. Others have proposed methods for forecasting the potential impact of global warming on the energy use [5, 6]. A number of

methods were presented, and these can broadly be grouped into two categories - ‘‘top-down’’ and ‘‘bottom-up’’. Statistical and archetype techniques are examples of the bottom-up methods. Many studies in to modelling CO2 emissions have been conducted using statistical techniques, such as those of Snakin [7] and Hirst and Goeltz [8]. Simultaneously, various researches have been carried out using the archetype techniques [9-12]. A principal advantage of bottom up methods is that they mainly rely on computer programs, and thus have the ability to analyse in detail the energy consumption characteristics of each building or sector. For example, Clarke, Ghauri and Johnstone [13] focused on the main determinants of energy demand in the building sector using the insulation level, capacity level, capacity position, air permeability, window size, exposure and wall to floor area ratio. Hirano, Katoa, Murakami, Ikaga, Shiraishi and Uehara [14] developed an archetype model with respect to Japanese buildings in order to show the effectiveness of porous residential buildings in the light of cooling energy and CO2 emission reductions. An alternative approach was taken in China by Wan and Yik [15], where the focus was on solar gains. The next section presents a bottom-up model for forecasting space cooling energy and its associated CO 2 emissions in the UAE housing stock. The paper studies the ways in which CO 2 emission levels are affected by global warming and how such levels can be reduced through the use of different building energy efficiency measures. The applicability of this model is demonstrated through a case study from Abu Dhabi.

2. METHODOLOGY AND MODEL DATA Three classes of data were used to construct the models: future climate data, current housing stock and energy consumption data of Abu Dhabi.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The general characteristics of Abu Dhabi’s climate resemble those of arid and semi-arid zones: summers are very dry with temperatures rising to about 48°C in coastal cities – with accompanying humidity levels reaching as high as 90%. In the southern cities temperatures can reach 50°C. Arid regions such as Abu Dhabi are sensitive to global climatic changes and the effects they produce. The Environment Agency of Abu Dhabi and the Ministry of Energy and other concerned parties in the UAE [16] have stated that temperatures in the UAE regions could increase while precipitation levels st could significantly decline by the end of the 21 century. This scenario was simulated and the output were generated at the regional level and then scaled to eight cities within the UAE including Abu Dhabi, Dubai, Sharjah, Al-Ain, Ras al-Khaymah, Khawr Fakkan, Umm al-Qaywayn, and Ajman. The annual average temperatures in 2050 are projected to be between about 1.6ºC and 2.9ºC warmer than they were over the period 1961-1990, and between 2.3ºC and 5.9ºC warmer by 2100. The reasons why the climate of the UAE is tending to get warmer are numerous and include the urban heat island effect, changes in atmospheric pollution and increases in greenhouse gas (GHG) emissions. This tendency will impact upon the built environment and the energy use in buildings.

generation is included, the five sectors account for all energy consumption in the economy of Abu Dhabi. Figure 3 shows electricity consumption per sector in Abu Dhabi emirate. It can be seen that buildings make up about 50% of the national consumption of electricity.

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2.2. Housing stock data Three key data sources were used for this study: the UAE in Figures [17], Sheikh Zayed Housing Program [18] and housing statistics provided by the Abu Dhabi Municipality. As depicted in Figure 1, Abu Dhabi has the largest number of housing units in the UAE. Figure 2 shows the percentage of housing units by housing type in Abu Dhabi emirate. It is clear that the flat type occupies the first position followed by the traditional house type. Seven representative buildings were used in order to ensure a good demonstration of the mainstream housing topologies. The representative buildings were chosen after applying certain criteria and data filters, including building categories and system types and operation schedules. The building category filter was applied to select buildings with the same basic type (e.g., flat, villa or traditional house). The building systems and operation schedules filter was applied to define the group for evaluation. This allows representatives of the major typical class of residential buildings to be obtained and the physical and operational characteristics of such buildings to be analysed. Detailed architectural, functional and operational data for the buildings were obtained from governmental statistics, working drawings, utility bills and field visits. Complete details of the physical and operational characteristics of the villa type housing are shown in Table 1. 2.3. Energy end-uses data In Abu Dhabi energy is consumed in five broad sectors defined by four end-users, namely buildings, agriculture, industry and others. If electricity

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Two storey Bldg 7%

Villa 15%

Figure 2: Housing units per housing type.

Table 1: Details for villa-type housing. Parameters

Specification

No. of Floor

2

Total Area

370- 415m

Floor Height External

3.5 m 15 mm concrete masonry units

walls

2

block-24 mm of plaster inside and outside

Roof

200

mm

concrete,

screed,50mm

sand

slab and

ceramic tiles WWR

0.25 & 0.3

Glazing

6 mm single green glass

Infiltration

5.0 m /h/m

3

2

Ventilation

7.5 L/s/person

Thermal

Multi-zones

Zones Equipment

12 W/m

Lighting

8 W/m

2

2

HVAC

Split units

Occupancy

25 m /p

2

50mm 10

mm

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Others 5%

Buildings 50%

Industry 25%

Agriculture 20%

models were simulated with respect to the projected climatic scenarios and three thermal design parameters - thermal insulation, window area and glazing type, as shown in Table 2. It is important to note that these parameters were chosen due to the fact that Abu Dhabi began planning regulation efficiency codes for buildings. These codes include thermal insulation, window area and low-energy glazing. This resulted in 120 prototypes of simulation models. Table 2 Thermal design parameters.

Figure 3: Energy consumption per sector. Flat

80

Traditional.House

Insulation Thermal insulation

Villa

U-factor 2 (W/m /K)

Roughnes s

Absorption

Exi- wall-1

2.32

3.0

0.7

40

Ass- wall-2 Exi- roof -1 Ass- roof -2

0.30 0.60 0.20

3.0 0.9 0.9

0.7 0.5 0.5

U-Value 2 (W/m /K)

SC

SHGC

Single

6.3

1.00

0.86

Double

2.78

(%)

60

20

Window Glazing type

0 Lighting

Air-con.

Equip

DHW

Figure 4: Energy end-uses.

In order to match the load shape of simulation models to the electricity generation it is essential to identify the pattern of energy use of the representative buildings and to predict domestic load profiles. Figure 4 shows the energy end-uses of the representative buildings (flats, traditional houses and villas). It is clear that electricity used by the AC system is the most significant, particularly for cooling energy, which requires more than 65% of the total electricity consumption to satisfy the cooling and ventilation loads. The remaining is divided between lighting, equipment and other building loads. 2.4. Model construction Archetypes were first developed and then simulation models used. The outcome provided the basis for developing a statistical bottom-up model for the housing stock 2.5. Archetypes and simulation models As stated above, temperatures are projected to be between about 1.6ºC and 2.9ºC warmer than they were over the period 1961-1990, and between 2.3ºC and 5.9ºC warmer by 2100. Based on real climatic elements, a statistically-based weather data file was generated using MeteoNorm software [19] to reflect the current climate. In order to predict the impact of higher air-temperatures on the electricity performance, the air-temperatures were increased by 1.6, 2.3, 2.9 and 5.9°C. These increases were referred to as Scenario-1, Scenario-2, Scenario-3 and Scenario-4, while the current climate was indicated as the baseline climate. Each scenario represented a weather input to the sophisticated simulation program Visual DOE [20]. The audit materials and monthly utility bills of the archetypes were used to calibrate the Visual DOE program. The

Window area (%) Climatic scenarios (°C)

60 baseline

0.89 40 + 1.6

0.77 20

+ 2.3

+ 2.9

+ 5.9

2.6. A statistical model Based on the outcome of simulation, a simple regression model was developed. This model considered the increase in air temperature, building thermal design, schedule of operation and the conversion factor of fuel. The primary analysis of such a model was based on a weighted ordinary least squares regression. This basic form of regression allows for analysis of a dependent variable (e.g. cooling energy requirements, electricity consumption or CO 2 emissions) subject to various independent variables (v) such as air-temperatures, building design or working hours. This linear regression can yield an equation of the form:   11  22    

(1)

In the current case, the cooling index (CI) is the dependent variable and variables on the right side of the equation are the independents, where C1, C 2, and Cn represent the equation coefficients and B is a constant. The developed model is structured to have the dependent variable to be CI. It is equal to the total cooling load divided by the gross floor area of the building. Back to equation (1), if v1, v2, v3 and v4 represent the air temperature, (Tao), U-value (u), window area (a) and the glazing type (g), then the values of C 1, C 2, C3 and C 4 represent the statistical correlation between the independent variables and CI. This correlation approximates to the average relationship between these independent variables 2 and each kWh/m /yr of cooling energy index.

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The linear regression can be expressed as:

3. RESULT AND DISCUSSION

  1  2  3  4  

(2)

    1

(3)

The result of regressing the CI as obtained from the simulation models on the above-mentioned independents is depicted in Table 3. The coefficients 2 of determination, or R of the CI, are 0.932, 0.961 and 0.947 for flats, traditional house and villa respectively, which would indicate a strong relationship between the CI variables and the outside temperature, U-value of the wall, the type of glazing and window area. To obtain the increment rate due to each variable. The following equation was used, where i is the increment rate, FCI is the future CI and P CI, is the present CI:

C2

C3

C4

B

18.0 0.9

8.3 0.2

103.8 8.1

21.2 1.0

1.3 0.3

204.8 9.1

Flat 25.9 2.6 5.1 0.4 0.932 R F 427.0 Traditional house 31.7 2.9 5.7 0.5 2 0.961 R F 578.8 Villa 36.0 7.0 2 R 0.947 2

The amount of electricity consumption (Ec) is subjected to the CI, building gross area (A) and working hours (Wh), as illustrated in equation (4). The CO2 emissions (Ce) are dependent on the electricity consumption and the conversion factor of fuel (Cf). Equation (5) shows a simple linear equation to calculate the CO2 emissions of each type of buildings.            

(kWh/m2 /yr)

427.0 80 75 70 65 60 55 50 45 40

(4) (5)

The developed model estimates the cooling energy consumption of each housing type with respect to the current and future climates. The energy consumption estimates are then scaled up to be representative of the regional and national housing stock by multiplying the results by the number of houses which fit the description of each type. The total CO2 emission of housing stock is obtained by multiplying the amount of energy consumption by the conversion factor of fuel. The total CO2 emissions can be obtained by summing the amount of CO2 emitted by each housing type.

Measured

Archetype

T. house Villa T.s Bldg Flat

Regression

Annex Studio Other

Figure 5: comparison of cooling indices. Measured consumption 1600 1400 1200 1000 800 600 400 200 0

Archetype

Regression

MWh

F

3.1. Forecasting future trends Figure 5 illustrates the actual measured cooling energy indices of the representative buildings as obtained from the provided data and field studies, and compares them with those obtained from the statistical model and validates them using the indices obtained from the well-validated simulation software Visual DOE. By considering the numbers of each housing type and measured data of electricity consumption, the total amount of electricity is calculate and compared with the result obtained from the models. Figure 6 shows the energy consumption of each housing type due to actual measurements and due to models. The difference between the measured indices and those from archetype and statistical models is within the range of 3.5% to 6.5%. This level of error is considered to be acceptable in forecasting models.

Table 3: Regressing the energy cooling energy index.

C1

For generating confidence in the results, the validation of a model is essential. To do so, this section evaluates the performance of the developed models by comparing the results of modelling the present performance of buildings with known energy consumption data. The same can be done to forecast the future performance. The difference is that a forecast generates new weather conditions in addition to modelling changes in building design, whereas the present climate involves only the latter. Since the modelling of a new design involves exactly the same methods and objects as the modelling of an existing design, the accuracy of predicting the present performance can be used as an estimate of the confidence in a forecast.

T. houseVilla T.s Bldg Flat Villa AnnexStudio Other Figure 6: energy consumption per housing type.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

With the increase in air temperatures it is expected that there will be a considerable growth in energy demand for cooling buildings. To establish the likely annual cooling demand for future scenarios the changes in demand were related to the energy consumed for cooling the representative buildings. Figure 7 illustrates the impact of global warming on cooling energy demand. There is a sharp increase in cooling demand with different rates ranging from 8.2% to 24.1% under Scenario-1 and Scenario-4 respectively. These figures are a clear indication that the global warming will lead to a negative impact on the total electricity demand, where changing from the baseline climate will increase the annual cooling energy demand, and therefore, additional total energy will be consume. From the total energy increase there will be, in effect, a further CO2 increase, with electric cooling energy consumption. The statistics of energy consumption per sector indicate that the residential sector in Abu Dhabi accounts for 2646 GWh, or almost 50% of the total regional consumption. If global warming delivers a 5.9°C air temperature rise then the consumption could be increased to almost 2977 GWh, and consequently the total CO 2 emissions will grow to almost 7.6 million metric tonnes. The net Emirati CO2 emissions could increase to around 138.4 million metric tonnes over the next few decades. Cooling

kWh/m2 /yr

24.1% 11.8%

300

12.5%

280 4.4%

260

250

16.7%

8.2% 6.3%

300

200 150

9%

100

kWh.m2 /yr

Electrcity 320

in comparison with the representative buildings is significant in all cases. The total electric energy saving was also modelled. It is clear that the thermal insulation, on the one hand, produces significant electricity savings in cooling energy demands and has a considerable effect on the total electricity use. The electricity saving is within the range of 15.9%. On the other hand, the window code, particularly the window area, is less effective. It offers between 4.5% to 8.1% reduction in the total electricity demand. The glazing system is more effective than the window area and it represents a good option because it is able to save a large amount of electricity used for cooling buildings coupled with considerable reductions in the total electricity demand that can reach 9.8%. Another objective of the developed models is to forecast the way in which CO2 emission levels are affected by different building codes. Figure 8 show the reduction in CO2 emissions due to each building code. The illustrated figures indicate that the thermal insulation code performs best, followed by glazing system code and then window area code in descending order. Table 4: Impact of building regulations. Climate B-line Sc-1 Sc-2 Reduction due to thermal Cooling 19.3 19.7 19.9 Electricity 15.5 15.9 16 Reduction due to glazing system (%) Cooling 5.4 5.4 5.5 Electricity 4.5 4.6 4.7 Reduction due to glazing area Cooling 8.5 9.1 10.9 Electricity 7.2 7.7 9.8

Sc-3

Sc-4

19.7 15.9

15.5 13.1

5.5 4.7

10.5 8.1

8.4 7.4

8.3 7.4

50 0

240 B-line

Sc-1

Sc-2

Sc-3

Sc-4 210

Figure 7: Impact of global warming.

Basecase Glazing sytem

Thermal insulation window area

Table 4 shows the yearly cooling energy demands and electricity savings due to each code under different scenarios. The space cooling energy in the representative houses is within the range of 65 - 70%. As tabled, decreasing the U-value, under the baseline climate, reduces the residential cooling demand by approximately 19.3%. Considering the large amount of cooling energy demand this figure is significant. When the same U-value is used under scenario-2, the figure grows to 19.9%. Reducing the thermal transmittance value of the building envelope significantly influences the cooling energy demand. The alteration of window parameters offers fewer savings for residential buildings. The impact of using efficient glazing system in the residential buildings is varied. The maximum reduction occurred under Scenario-4 with a 10.5% drop. The same situation can be observed with respect to the window area. The maximum saving is 10.9% when the window area is reduced under Scenario-2. This percentage, however, decreases to 8.3% under Scenario-4. It is obvious that the reduction due to window parameters

(Kg/m2/yr)

200

3.2. Modelling building regulations

190

7.4%

180 170

8.1%

160

13%

150 140 Baseline

scenario-1

scenario-4

Table 8: Impact of building regulations.

To this end, the figures estimated, due to the developed models, are doing well when compared with those presented in Ref [21]. It is clear, therefore, that the developed model is likely to be an effective tool in forecasting future trends of CO2 emissions and in evaluating the impact of efficiency regulations on building performance under global warming scenarios. Such a model can guide decisions of policy regarding the housing stock. The policy measures, such as energy efficiency regulations, have an immediate impact in the housing practice. The present models are well applicable to studies on such operations.

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4.

CONCLUSION

This study introduced a statistical model for forecasting cooling energy consumption and its associated CO 2 emissions under global warming scenarios. The accuracy of predicting the present performance was used as an estimate of the confidence in a forecast. The difference between the measured indices as obtained from real statistics and the archetype and regression models is within the range of 3.5% and 6.5%. This level of error is considered to be acceptable in forecasting models. The objective of the developed model is to improve the quality of energy consumption and CO2 emission data, especially for the benefit of local and national decision making. Some policy measures have immediate impacts in practice. These include energy efficiency regulations, promoting the use of green materials (thermal insulation and low energy glazing) and changing the electricity supplier through the switch towards green electricity or the installation of more efficient power plants with low conversion factor of fuels. The present model is highly applicable to studies of these operations.

5. REFERENCES [1] D Jenkins, Y Lui, AD Peacock. Climatic and internal factors affecting future UK office heating and cooling energy consumptions, Energy and Buildings 2008, 40: 874–881. [2] H Rosenlund. Buildings in a changing climate Effects of Global Warming on Energy Use, Proceedings of the 24th International Conference on Passive and Low Energy Architecture (PLEA), Renewable Energies and Energy Efficiency, Singapore 2007, 128-134. [3] MR Gaterll, ME McEvoy. The impact of climate change uncertainties on the performance of energy efficiency measures applied to dwellings, Energy and Buildings 2005, 37: 982–995. [4] IC Ward. Will global warming reduce the carbon emissions of the Yorkshire Humber Region’s domestic building stock—A scoping study. Energy and Buildings 2008: 40: 998–1003. [5] R Zmeureanu, G Renaud. Estimation of potential impact of climate change on the heating energy use of existing houses. Energy Policy 2008, 36: 303–310. [6] E Mansur, R Mendelsohn, W Morrison. Climate change adaptation: A study of fuel choice and consumption in the US energy sector. Journal of Environmental Economics and Management 2008, 55: 175–193. [7] JPA Snakin. An engineering model for heating energy and emission assessment-The case of North Karelia, Finland. Applied Energy 2000; 67: 353-381 [8] E Hirst, R Goeltz, D White. Determination of household energy using ‘fingerprints’ from energy billing data. Energy Research 1986; 10(4):393–405.

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[9] A Parekh. Development of archetypes of building characteristics libraries for simplified energy use evaluation of houses. IBPSA, ninth international conference, Montreal, Canada; 2005: 921–8. [10] C Weber, M Koyama, S Kraines. CO2-emissions reduction potential and costs of a decentralized energy system for providing electricity, cooling and heating in an office-building in Tokyo. Energy 2006; 31: 3041–3061 [11] R Yao, K Steemers. A method of formulating energy load profile for domestic buildings in the UK. Energy and Buildings 2005, 37: 663–671 [12] B Rolfsman. CO 2 emission consequences of energy measures in buildings. Building and Environment 2002; 37:1421 – 1430. [13] JA Clarke, S Ghauri, CM Johnstone, JM Kim, PG Tuohy. The EDEM methodology for housing upgrade analysis, carbon and energy labelling and national policy development. IBPSA Canada, eSim conference, Quebec City, Canada; 2008: 135–142. [14] T Hirano, S Katoa, S Murakami, T Ikaga, Y Shiraishi, H Uehara. A study on a porous residential building model in hot and humid regions part 2—reducing the cooling load by component-scale voids and the CO2 emission reduction effect of the building model. Building and Environment 2006; 41: 33–44 [15] KSY Wan, FHW Yik. Representative building design and internal load patterns for modelling energy use in residential buildings in Hong Kong. Applied Energy 2004; 77: 69–85. [16] Ministry of Energy. Initial National Communication to the United Nations Framework Convention on Climate Change. United Arab Emirates, 2006. [17] Ministry of Economy of UAE. UAE in Figures 2008. http://www.economy.ae/English/EconomicAndSt atisticReports/EconomicReports/Pages/default.a spx [18] Sheikh Zayed Housing Program. http://www.gcchousing.org/stat/ae.pdf [19] J Remund, R Lang, S Kunz. MeteoNorm V.5.1 Software and Handbook on CD-ROM. Meteotest, Fabrikstrasse 14, 3012 Bern, Switzerland 2003. [20] Architectural energy Corporation 2004. Visual DOE User Manual, USA. [21] H Radhi. Evaluating the potential impact of global warming on the UAE residential buildings – A contribution to reduce the CO2 emissions. Building and Environment 2009; 44, pp: 24512462.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Environmental design of a building Climatic context Charline WEISSENSTEIN1, Jean-Claude BIGNON1 1

Map-Crai, University of Lorraine, Nancy, France

ABSTRACT: This article concerns the climatic context related to the environmental assessment of projects at their preliminary phase of design. An evaluation method is proposed, which is based on the definition of objectives and assessment criteria, as well as on the introduction of a “contextual weighting” system. These weights allow us to adjust the evaluation of various issues related to the “climates” of each project.Our purpose relates here to the identification of climatic data influencing the evaluation criteria in order to define context coefficients. Keywords: Environment, assessment methods, climatic context, architectural design.

1. INTRODUCTION The issue of sustainable development and more precisely related environmental matters are key stakes to consider in buildings, and more particularly in architecture. Evaluation methods of environmental quality are currently recognised as mandatory in these design approaches. However, the concept of quality cannot be defined abstractly and must be connected to a context and more particularly a climatic context. This is why we set up a contextual assessment method for buildings environmental quality, in order to assist the work of architectural design. It has three characteristics: It is based on a global model defining environmental criteria used in the evaluation process; It is adapted to the different phases of architectural design; it takes into account specificities of each operation. This article presents the development of the third point, the taking into account of specificities of a project and more particularly specificities in terms of climatic context. The proposed method allows us to adapt the environmental assessment to the specific climatic context of each project by using a weighting criteria called “context coefficient”. Firstly, we propose a climatic classification adapted to the design process. Secondly, we define a first version of “context coefficients” based on this classification. And finally, we validate this weighting system by a survey conducted on architects.

2. CLIMATIC CLASSIFICATION 2.1. Definition The climatic context can be defined by the description of the weather conditions of a given area which can be established using various data such as: temperature, pluviometry, amount of sunshine, humidity, etc.

Classifing climates therefore consists of organizing these data, in homogenous zones of similar climates. The data taken into account for this classification depend on the goal and the required precision. This second part presents some classification examples, differing in terms of goals and required data. 2.2. The Köppen classification The Köppen classification was put forward by Wladimir Peter KÖPPEN in 1920 [1]. The data required to use it are precipitations and temperatures. The method has three stages, within each of which different climatic definitions are used. The first stage characterizes five climate types (Table 1). They are identified by temperature and pluviometry characteristics. Table 1 : 1st stage of Köppen classification.

code A B C D E

Climate types Equatorial aride warm temperate snow polar




For example, the “warm temperate climate” is defined by : The average temperature of the three coldest months between -3 °C and 18 °C; the average temperature of the hottest month above 10 °C; seasons, summer and winter, must be well defined. The second phase refines this first characterization according to the pluviometric regime. And similarly, the third stage specifies the annual temperature variations. For example the climate classified as “Csa”, representing the Mediterranean climate has the following characteristics: Climate type: moderately hot; pluviometric regime: precipitations between 380 and 760 mm;

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-

temperature variations: hot summer. The final proposal contains about thirty climate classes, identified by and organized in codes of two or three letters, which correspond to the three stages of the classification system. This method allows a precise and detailed climate characterization. This system was refined little by little. The current version is that presented by Rudolf GREIGER in 1961. This classification remains a reference thanks to regular updates in the fields of hydrology, geography, agriculture and in the study of climate changes. 2.3. Holdridge Life Zones System “The holdridge life zones” is a method of climatic classification published by Leslie HOLDRIDGE [2], that relates climates to their associated vegetation types. This classification is shown as a triangle for which each axis represents a climatic factor (refer to fig. 1), precipitations, humidity, and the ratio of the potential of evapotranspiration. The system also integrates three other indicators, namly biotempérature, altitude and latitude.

category 4-openings 5-walls 6-roofs 7-sleep 8-rain

Type / Heavy walls Heavy roofs Sleep outdoors Rain protection

The climatic data considered are: Temperatures (average, minimum and maximum). Humidity, precipitations and wind. Comparison of comfort limits. These data make it possible to characterize climates and thus to propose guidelines for an adapted construction. -

2.5. Givoni bioclimatic chart A method suggested by GIVONI [4] as early as 1963 defines the main roads of construction according to the comfort zones. The method support is the psycometric diagram (refer to fig. 2) which represents the human comfort zone based on temperatures and air humidity. The method indicates, based on climatic conditions, where the confort zones are located and thus shows the axes of construction to be followed.

Figure 1: Holdridge Life Zones diagram.

Each zone corresponds to particular climatic characteristics and thus to defined vegetation types. The system determines thirty-eight different classes such as « polar desert », « warm temperate dry forest », « subtropical dry forest », « tropical desert scrub », etc. For example, in the subtropical category, the “dry Martini forest” is characterized in the following factors : biotempérature 12-24° C; potential evaporation ratio : 1-2; humidity: subhumid; average total annual precipitation : 50-100 cm. 2.4. Mahoney tables The MAHONEY tables [3] characterise climates and with the aim of proposing recommendations for construction. These recommendations (seventeen) are divided into eight categories. For example, in the tropical monsoon climate (table 2): Table 2: Monsoon climate recommendations according to C. Mahoney.

category 1-plan 2-spacing 3-air

2

258

Type orientation longitudinal axis E-O wide spacing + wind portection intermittent circulation of air

CLIMATIC, WATER AND BIODIVERSITY CONTEXT

Figure 2 : Bioclimatic Chart [5]

2.6. Conclusion Classification methods make it possible to characterise climates and their associated typologies of vegetations, constructions, etc. For classifications more related to construction purposes (Mahoney, Givoni), at least two problems can be foreseen. Firstly, climatic typologies are primarily guided by a dominating objective: the hygrothermic comfort. Although important, this objective should not be the only one. In architecture, other considerations can be influenced by the climate, such as visual comfort (quantity of day light, dazzling…), or water management. Secondly, the climatic data considered are often too detailed, which is not necessarely relevant with the preliminary design phases. We thus propose a method which tries to answer these questions.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

3. METHOD 3.1. Climatic data The starting point of our work is based on an approach first developed by Manon Kern [6] and used by the CRIT Architecture. This assessment approach of environmental quality of buildings was put forward based on a study of the existing certification methods (BREAM, LEED, HQE…). The method was based on the evaluation of twenty-four targets, organized in phases, corresponding to the process of design and realisation (from preparation to occupation). Each objective was evaluated by experts, ranking from 0 to 4, the average mark giving the project value. This evaluation was accompanied by a “radar” chart, as a help in comparing projects. Applied on several occasions for buildings evaluation, this first version of the method was then criticised, in view of the criteria considered in the objectives evaluation and the need to determine more efficiently the context of each project. We thus proposed to refine targets by defining them more precisiely in various criteria (table 3) and in taking into account the characteristics of each operation by defining a “context coefficient” (CC). Table 3: Hierarchical method segmentation.

Target 1 Criterion 1.1 Criterion 1.2 Criterion 1.3 Target 2 Criterion 2.1 Criterion 2.2 Criterion 2.3 ...

CC CC CC CC CC CC ...

The aim of our work is to adapt the environmental evaluation according to the context of each project. The context is defined by the nature of the construction (new, rehabilitation…), the type of program (multifamily appartments, single house…), geographico-urban data (built-up area, isolated…) and climatic considerations. From now on, we will limit ourselves to presenting the climatic data of contextualisation. Initially, we tried to define standard climates associated with a specific weighting (refer to fig. 3). climate 1 criterion

Figure 3 : 1st phase of reflection

The characterization of elements in limited numbers raises the question of their. Defining a limited number of elements makes it possible to have a simple model, but it integrates only a small number of cases. On the contrary, determining a large number of elements makes it possible to consider more cases, but makes the model complex. Making only five climate types (dry heat, wet heat, moderate hot, moderate cold, polar) does not allow us to propose a relevant model for a large number of situations. For example, in such a model

the monsoon climate type, which has a hot wet period as well as a hot dry period, would not be represented in such a model. It however induces constructive singular characteristics which are neither those of a hot and wet climate, nor those of a hot and dry one. To have a model adapted to all design cases, it would be necessary to characterize the whole array of possible climatic situations, which would make the model complex. In a second phase, we reversed our reasoning (refer to fig. 4), looking at which climatic data influence the importance of the evaluation criteria. influenced climatic data by criterion climatic data

Figure 4: 2nd phase of reflection.

This makes it possible to restrict the data input to the only useful elements for the criteria definition, while preserving the effectiveness of the model. All climates can be considered as well as microclimates. Indeed, the method takes into account the climatic data from a given point and not an average of a region. The climatic data generally considered to influence the environmental quality of a building are: temperatures (variations, averages); pluviometry (rain, snow); winds (speed and direction); sunshine (hour, radiation, nebulosity); humidity; localization (latitude, longitude, altitude, solar trajectory). Our method objectives being to bring help in the early phase of design, all data available and useful at this moment in the design process must be defined. It is thus not necessary, in the early phases, to obtaine detailed climatic data. The latter will be crucial only at the end of the process, to optimize dimensioning of the architectural elements. On the other hand, it is essential to have a notion of the climatic conditions in which the project will take place. It is also possible to estimate certain information by deducing it from other data. According to the temperature and pluviometry, it is for example possible to deduce the relative humidity and the potentiality of snow cover. We thus propose to retain as essential data at the preliminary phases of design: Notion of low and high temperatures (Tb and Th). Value: high, very high, etc Notion of the amount of pluviometry (P). Value: important, very weak, etc Notion of winds (V): intensity, direction. localization, latitude (L); pole, tropic, equator. In our method, we have thus indicated, for each evaluation criterion, a selection of climatic data influencing the design.

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3.2. Assumptions To determine these influences and to establish the context coefficients, we studied vernacular architecture and recent sustainable architecture. Indeed, the study of these architectures has allowed us to observe the design characteristics specific to each climate (refer to fig. 5). For example, light architecture, and large roofs are typical of the architecture of a hot and humid climate. In contrast, in a hot dry climate we find the following features: a heavy compact design and a flat roof. The architecture in climates having both a hot dry period and a hot wet period has the characteristics of both climates.

After having identifie which climatic data influenced each criterion, we formulated a first hypothesis about the criteria weighting system taking into account the climatic data. Five class levels were proposed : / not important + slightly important ++ fairly important +++ important ++++ very important The summary of the proposals is presented in a table which indicates the importance of the criteria according to the associated climatic conditions (table 4). Table 4 : importance of the criterion

criterion hot wet

intermediate

hot dry

++++ +++

To collect, Direct Optimized manage the solar radiation orientation of contribution protection sunlight s Th average tb very low L tropic to very high Tb low L pole or and equator L : pole

++

Tb average

th low

-

+

tb high

-

-

-

Tb very high th very low

-


 Figure 5 : architectural typology. Above: secondary school, J.A.G. (Papaïchton, Guyana), Primary school, Diébédo Francis Kéré (Gando, Burkina Faso), Womens’s community centre, Saija Hollmén, Jenni Reuster, Helena Sandman (Rufisque, Sénagal). Below, vernacular architecture: Benin lake village [7], Bhil village, India [8]; Yemen [9].

So we have for each climate a particular type of architecture, and therefore unique needs. These needs can be analyzed through the study of these types. In the example of a hot humid climate, the chareteritic of a large roof indicates the need for protection from the rain and sun, whereas the characteristic of light architecture indicates the need for continuous circulation of air. These needs correspond to the different assessment criteria established. We were therefore able to identify which climatic data influence criteria (refer to fig. 6).

4.

VALIDATION

To validate our proposals, we carried out a survey involving building professionals. These were primarily European architects, but we also included designers involved in more contrasted climatic areas. The validation corpus thus included about fifty projects covering a dozen different climatic contexts (Australia, South Africa, Brazil, India, the USA, Canada…). The survey was carried out using a questionnaire aiming to measure the relative weight of evaluation criteria in the design process, according to the contrasted climatic context. Designers were required to answer based one the positions taken in particular projects, not on their general opinion. Each designer was thus requested to indicate the climatic context of the project and to indicate the importance of each criterion in the project (table 5). Their appreciation was accompanied by a comment in order to give more precision. Table 5: example of returned questionnaire, Catsieau Architect in Guyana, project for old people's home.

criterion

Figure 6 : relationship between architectural typology, needs , criteria an climatic data.

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influence

Optimized, orientation of sunlight

/

To limit direct light and dazzling.

/

comments Without object; Existing buildings and quasi vertical sun Without Object; Sun very quickly at the zenith

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

To manage infiltration and water run-off on the plots. Protection from strong precipitations. (External Spaces)

++++

+++

such situations. It is more important to be isolated and protected from the cold.

pluviometry very strong Conform to way of life under open shelter

These questionnaires enabled us to appreciate the weight of each criterion in well-defined climatic contexts and thus to refine and validate the preliminary assumptions.

Figure 8: national opera, Snohetta (Oslo, Norway)

Thirdly, whereas certain criteria did not appear to us to depend on climate, they appeared sometimes to be related to it. For example, the criterion “external extensions (loggia, balcony, terrace…) ” which could appears as not very dependent upon the climatic context is on the contrary very related to it. Our survey revealed that in hot climates these elements were part of the life philosophy and thus were very important (refer to fig. 9); whereas in a cold climate this criterion is not prevalent, and even useless.

5. RESULTS AND DISCUSSIONS Results must be relativized, based on the fact that the remote survey did not allow exchanges and direct dialogs, and therefore does not guarantee an exact comprehension of the question elements. Indeed, we have noticed that certain criteria were not understood correctly. However the comments allowed us to correct some comprehension problems and to draw a certain number of conclusions. Firstly, the results of the various investigations clearly confirm the need to contextualize the criteria, according to the specific situations of each project. We noted that the importance of the evaluation criteria fluctuates effectively according to the climatic context of the operation. Secondly, we refined our original weighting proposals. Some were validated, but others had to be modified. For example, a starting hypothesis that “in a dry climate, there is no need to infiltrate and control water” was confirmed. This confirmation was based, for example, on an answer given to our survey, from a school project in Zanskar (northern India), directed by the architect Jan Tilinger (refer to fig. 7), where the pluviometry is relatively low.


 Figure 9: R.R House, Andrade & Morretin (Sao paulo, Brasil)

Finally, we clearly identified, thanks to the designers’ comments, the key climatic data influencing evaluation criteria (table 5). This allowed us to refine our method. Table 5: example of climatic data influencing the criteria

criteria Collect, manage solar contributions Temporize heat


 Figure 7 :Bioclimatic school, Jan Tilinger (Kargyark, India).

On the other hand, the hypothesis that “it is very important to collect solar radiation in any cold climate” was revised based on the answers from different projects in Sweden and Norway directed respectively by the agencies S-XL architects and Snohetta (refer to fig. 8). Indeed in the cold climate at the poles, the sun is not very present, even absent, at the coldest periods. This criterion although important is thus not the first to be considered in

Collect rain water Optimize orientation of sunlight Orientation compared to wind External extensions

influence - temperature (low)

-

latitude - temperature (high) - pluviometry - pluviometry - latitude - wind - temperature

6. CONCLUSION In order to progress, the evaluation of environmental quality must be defined. This is an actual recognized need. However, quality cannot be defined abstractedly. The concept of context,

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although complex and subject to interpretation, must be an integral part of the evaluation methods. During this work, centered on the concept of climatic context, we identified the data required to adapt construction to climate at the preliminary design phases. We also defined the relative weight of each evaluation criterion to judge the quality of a project based on its context. The results of this study will be used to develop an evaluation tool, allowing the designers to propose projects offering better environmental answers. Complementary work in progress bearing on the concept of construction type or program should enable us to futher refine the projects’ contextualisation criteria as well as the weighting system in our evaluation method.

7. ACKNOWLEDGEMENTS We thank the unit architects who answered the survey and thus allowed the realisation of this research task.

8. REFERENCES [1] Kottek, M., Grieser, J., Beck, C., Rudolf, B., & Rubel, F. (2006). World Map of the KoppenGeiger climate classification updated. Meteorologische Zeitschrift, 15(3), 259–264. [2] Holdridge, L. R. (1967). life zone ecology (REVISED EDITION.). [3] UNITED NATIONS. (1971). Climate and House Design – Vol. I: Design of Low-Cost Housing and Community Facilities. Department of Economic and Social Affair. New York. [4] Givoni B. (1978). L'homme, l'architecture et le climat. Cep. [5] Guthrie, J. (2003). Architect's Portable Handbook (3 éd.). McGraw-Hill Professional. [6] Kern, M. (2004). Analyse du cycle conception environnementale. Mémoire de formation continue, Classe 4. [7] http://meriterroires.phpnet.org/international/wp/w p-content/uploads/2008/09/benin25-10-03159.JPG [8] http://www.pbase.com/croftcroyne/image/52516 393 [9] http://www.rahhala.net/images/carnets/37_2.jpg


 
 
 
 
 
 
 
 
 
 
 


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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Interdisciplinary methodological approach for urban water management in densely urbanized areas within Brussels Geology, history and architectural engineering Valérie MAHAUT1, Kevin DE BONDT2 and Chloé DELIGNE3 1

Université de Montréal, Montreal, Canada Vrije Universiteit Brussel, Brussels, Belgium 3 Université libre de Bruxelles, Brussels, Belgium 2

ABSTRACT: From centuries rivers and waterways have had an important impact on the development and the design of Brussels. But since the covering of the rivers and the reorganization of water networks in the course of e the 19 century, water circulates mainly underground and has disappeared from the surface of the city. At the same time water management was separated from others fields of the urban composition. Difficulties of managing floods that currently occur in Brussels are partly the result of this partition between city design and water management. This paper proposes an interdisciplinary methodology (including geology, history, architectural engineering) to innovate in the field of water management. Water management has to be understood as a thread to (re)think the city and its future development. To be improved, this methodology is applied it to a densely urbanized area that is representative of the greater Brussels metropolis from topographic, hydro-geological and historical points of view. Keywords: water management, history, hydrogeology, SUDS, rainwater

1. NEW METHODOLOGICAL APPROACH FOR URBAN WATER MANAGEMENT Brussels (nowadays called Brussels-Capital Region) has too long forgotten its past of "City of water". For two centuries, the urbanization has ignored topographical and hydro-geological realities and their implication on water cycles. Runoff on continuous increasing impervious areas contributes currently to frequent overloading of the combined sewer network inherited from the 20th century and to generate recurrent floods during intense storm events. The methodology suggested in this paper proposes an innovative way to think urban water management. This interdisciplinary vision is the result of the association of three researchers coming from different specialities (geology, history and architectural engineering) and conciliates technical, environmental and landscape aspects. The geological investigation aims to replace the subterranean geology of the city into its environmental context and to document its interactions with the urbanization. The historical point of view leads to understand the present hydrological situation, and gives some clue to underline relevance of future urban projects. The engineering coupled with architectural and environmental analysis allows validating technical solutions, defines their spatial and temporal dimensions and integrates them into the city development, emphasising the geological and historical contributions. This scientific and interdisciplinary work on urban water management is totally new in Brussels. It’s the first time that these three disciplines are discussed

and combined to produce a common knowledge to reinvent urban water management by inserting environmental, patrimonial and social aspects. The strong complementary of these three disciplines allows global answers to local scale flood problems. The proposed methodology aims to help decisionmakers and politics towards a more sustainable management of the city and its environment.

2. BRUSSELS CONTEXT: URBANIZATION AND WATER PROBLEMATIC 2.1. Background The Brussels-Capital Region is formed by the old city of Brussels and 18 surrounding communes. The territory of the Region is 161 km² for 1 115 000 inhabitants and approximately 1 million workers who come each weekday from the other Belgian Regions (Fig. 1). Its main river, the Senne, flows through the Region entering from the south-west at 20 meters above the sea level (asl), and leaving to the northeast (15 meters asl). On highs, top point reaches up to 120 meters asl in the southern part of Brussels. The relief is modeled by several Senne tributaries (Maelbeek, Molenbeek, Woluwe, Geleytsbeek…) which draw narrow valleys and slopes with strong grades. Valley bottoms are constituted by alluvial deposit on claystone, while highs are mainly constituted of sand alternating with clay layers and recovered by a thin loam blanket. These sands are more permeable (mainly Lede and Brussels sands). Rainwater infiltrates easier into sandy highs than into valley alluviums already watered. Water-tables in sand are

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deep and infiltrated water takes time to reach them before re-emerging at interface with deep claystone (often in the middle of valleys slopes).

2.2. History and urbanisation The Senne is considered “the” Brussels River given the economic role it has played in the city’s development since the Middle Ages. Beside the Senne, seven tributary streams ran through the th Brussels area (Fig. 1). Until the the 19 century, their flows were intensely exploited to operate a large number of mills and an important fish farming industry. The number of ponds dedicated to fish farming (dug in medieval times) was impressive, particularly on the east side of the Senne Valley, as it can be seen on the Ferraris map (ca 1775, Fig. 3). In th other words, at the end of the 18 century, the waterways resembled more of a “water system” composed of channels, reservoirs and interconnections than a single, continuous flow of water.

Figure 1: Hydrography and topography of the BrusselsCapital Region.

This situation is current on the large part of Brussels (in South, East and North) although the South-West presents a gentler relief because a more important thickness of loam and the absence of sandy geological layers (Fig. 2). Hence it is obvious that rainwater preferential paths and fluxes are related to topographical and geographical realities in Brussels.

Figure 3: The “water system” on the Woluwe at the end of th the 18 century.

More than 0 meters More than 10 meters More than 20 meters More than 30 meters More than 40 meters More than 50 meters More than 60 meters More than 70 meters Locality boundaries

Figure 2: Cumulative thickness of Brussels and Lede sands within Brussels-Capital Region [8].

The climate is temperate, mild and rainy. According to the geological and topographical background, the flows of Senne catchment are very responsive to the meteorological events, with low flow in dry weather and torrential flow in rainy weather.

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As many studies have shown Erreur ! Source du renvoi introuvable. [2] [3], the industrial revolution had radical consequences on the role of rivers. One by one, the activities (energy, artisanal, fish farming) that had engendered the coexistence of people and water disappeared leading to a rapid end to fish farms and ponds. In Brussels’ region, the area occupied by such ponds fell by nearly 60% from 1775 to 1860 (Fig. 4). Observation of flooding tends to indicate that this dramatic decrease had repercussions on the hydrographic system’s capacity to absorb floodwaters ; flood severity increased significantly in the course of the 19th century and caused more damage since the spectacular demographic growth had led to a massive urbanization (and increase of impervious areas) of the suburbs. This increase coupled with greater pollution [4], forced Brussels authorities to seek "solutions". The “solution” they found is known as the “covering of the Senne” (18661871), an urbanistic operation that “buried” the Senne in underground waterways, and used it as the

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

spin of the sewage network. All rivers will know the same lot in the course of the 19th century: they were transformed into a combined sewer network running under a newly urbanized landscape [5].

surroundings of the inhabitants, production of renewable energy from water and participation in the international policy about water management.

Figure 4: Massive decrease in “hydraulic annexes” on the Maelbeek River between 1775 and 1860.

2.3. Water problematic and the Brussels water management plan Today, Brussels enjoys an efficient drinking water network but also an old existing combined sewer system suffering from several collapses and overflows by stormy weather. The large majority of floods within BrusselsCapital Region are caused by overflow of the combined water system mainly during intense rains in summer and autumn. These floods are more and more frequent and cause more and more damage. An analysis of the data from the Fund of Calamities (Fig. 5) and flood declarations in Brussels determines a concentration of the phenomena in the bottom of valleys [6]. The efficient of the waste water treatment plant downstream the city is reduced owing to high proportion of clean water (rainwater, pumping water) coming at the plant. This dysfunction leads to additional charge and even to the complete stopping of the plant, as in December 2009. To struggle against floods, a storm water plan was adopted in 2008 by the government of the Region. It enumerates the main reasons of these repeated floods (increasing impervious areas, carelessness and unsuitability of the sewer system, disappearing of the natural zones under the urbanization pressure) and develops strategies to struggle against floods (reduction of impervious areas, setting up compensation and source control devices on private and public plots, reinforcement of the sewer system, construction of stormwater drainage reservoirs, restoration of the natural water network and wetlands for natural flood). A year later after the adoption of this storm water plan, the government of the Region established a larger water management plan [7] including different aspect of the water problematic. According to the European directive of the European Commission, this plan includes also quality of water, protected areas, cost, sustainable use of water, quantity of natural water supply, reintegration of water into the

Figure 5: Floods map made with data from the Fund of Calamities and flood declarations in Brussels, 1999-2005 [8].

2.4. Ambition of the present study The water management plan is fitting together different fields concerned by water. It is the first step to an integrated water management. The methodology proposed in this paper follows the same direction as the water management plan but aims at exceeding it. Indeed it aims to integrate different disciplinary points of view and knowledge in order to propose a global urban approach where environmental as well as urban constraints, heritage and well-being of the inhabitants are integrated. Since the disappearing of water from the surface th of the city at the 19 century, water management was separated from others fields of the urban composition. Difficulties of managing floods that currently occur in Brussels are partly the result of this partition between city design and water management. This paper proposes an interdisciplinary methodology (including geology, history, urban development and engineering) to (re)link together city design and water management. Furthermore, water management has to be understood as a thread to (re)think the city and its future development [9].

3. GENESIS OF THE PROJECT While facing recurrent problems of floods and pollution, water management boards in numerous cities have recently opened to new visions, paying more and more attention to the global water cycle and considering infiltration of rain water into the soil as a key element in highly impervious urbanized areas. In order to choose the appropriate technique and the right scale of intervention, they need a good knowledge of underground environment and water circulation patterns. In the recent design and comparison tool made for the Brussels Region to help architects to manage

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rainwater at the plot scale [10] [11], the geological aspect is present and simplified in a coefficient of soil permeability. The hydraulics objective to choose and design compensation and source control devices are depending of the level of the permeability of land. De Bondt and Claeys distinguish areas where rainwater infiltration brings major benefit in the struggle against floods problems for the Brussels Region [8]. But this information is unfortunately far from being complete and accurate on local scale, and so remains inaccessible to the users of the tool. The deepening of geological knowledge is a real stake for the future of water management in Brussels. Moreover, it could lead to more appropriate decisions on urban development or to more cautious urban rules. In the perspective of a better understanding of (underground) water cycle in Brussels, the historical approach is also useful. Indeed, in a densily urbanized area where running water has been made invisible, the study of historical maps and data often gives some clue to the comprehension of some specific problems (location of ancient springs, existence of old hydraulic (net)works). On a more cultural level, beyond the fact that the history of water management helps us to understand present urban landscapes, it can also be used as thread for new urban project/proposition, either to recalls the links between the city and its water, or to give some inspiration for new technical solutions more respectful of the local hydrological context. Indeed, some technical choices made by past generations proved to be appropriate and respectful of the environmental context [12] [13] [14].  

4.2. Architectural enginneering-geology The second main line combines the works of the geologist and of the architectural engineer and aims at proposing a hydrogeological zonation for the covered territory based on topographical realities and local geology. Infiltration of rainwater into the soil rather than into the sewage system is indeed one of the compensatory measures (i.e. ways to avoid rainwater flows entering, or entering too rapidly, into the sewage system) that can be applied to minimize importance of floodings. Therefore, it is of great importance to evaluate the infiltration capacity of the different kind of soils that can be found on the covered territory and to classify them in different zones. This capacity will be evaluated (in situ) on the permeable part of the territory on small scale private projects. The expected outputs for each zone determine a maximum output flow as well as the infiltration capacity for small scale private projects as for new large housing estates. 4.3. History-architectural engineering The objective of the last main line is to propose concrete developments able to improve the management of floods and also to make the water circulation more visible and the water management more respectful of the environment. Flow reducing devices and “rain gardens” (layed out zones where water can be stored during rainy events) are some of the possibilities. The location and forms of these improvements would be carefully choosen in keeping with the “water” heritage/landscape. In other words, they would apply the precepts of a sustainable architecture.

4. ISSUE OF THE MULTIDISCIPLINARY APPROACH The methodology is based on three main lines, each of them combining two of the fields involved (geology-history, architectural enginneering-geology, history-architectural engineering) (Fig. 6). 4.1. Geology-history The first one aims at identifying the localization and nature of possible parasitic waters into the sewer network. These kinds of waters often come from “forgotten” rivers and springs or from ground water and contibute to increase the damage caused by the floods. Geological research (drill-hole and piezometric monitoring) and geo-chemical analysis of the sewage (stable isotopes method) are very useful to distinguish the different origins of the waters (ground water, rainwater ans tappedwater). They are also useful at tracing the existence and localization of the “invisible” waters and rivers. Historical survey of ancient maps and of written archives (especially 19th century archives coming from first water boards and administrations) bring complementary information about the localisation and course of the forgotten springs and rivers. This combined investigation is the first step towards a better understanding of the floods mechanics and hence towards action to minimise them (by separating them).

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Figure 6: Multidisciplinary approach including geology, history and architectural enginneering.

Gathered together, these lines would result in a proposition for a global management of water in the Brussels-Capital Region (either on public or on private scale) combining (1) the separation of sewage from other types of water (old rivers and springs), (2) a real “infiltration politics”, (3) local improvements of surface overland flows, and (4) the use of historic heritage as one of thread for more sustainable management and architecture. This global proposition would lead to the improvement of the flood situation and to a better working of the water treatment plant. At the same time, it will resutl in a greater conscience and respect of local water cycle.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

5. APPLICATION TO A CATCHMENT OF BRUSSEL

MICRO-

5.1. Description of the study-case area The study area (one of the Brussels district) is located in the southern part of Brussels, on the rightbank of the Senne Valley for a total surface around 2.7 square kilometres. The top reaches 90 meters asl while valley bottom is around 20 meters asl. Average grade is about 5%. Topography plays a deterministic role on urban water fluxes and flood occurrence in this area. This topographical difference is very important but quite common within the Brussels-Capital Region. Geological layers met in this area are also representative for a large part of Brussels (mainly East Brussels). The East-North-East oriented slope constitutes the main part of the micro-catchment. It also contains a South-oriented slope in Geleytsbeek Valley next to confluence with the Senne Valley. Both the Senne and the Geleytsbeek Rivers are now intimal related to or simply hijacked by the sewer network. The micro-catchment area is the topographical catchment of a sewer drainage system leading to the new stormwater drainage reservoir and to the South waste water treatment plant. The construction of the stormwater drainage reservoir is supposed to solve flood problems in this locality. It is planned to be functional in a few months but lots of floods listed between 1999 and 2005 are out of its impact area. Both South waste water treatment plant and stormwater drainage reservoir provide powerful data on sewage fluxes. As said before, urban hydrodynamics are now hidden by urbanization. Field and historical investigation are necessary in order to recover and understand these systems. Located in the Senne Valley, the historical sources relative to Forest Abbey are helpful to collect data on historical floods, resurgences and also old water managements. This micro-catchment is highly urbanized (and also covered by lot of impervious surfaces) but it still exist some places where new housing estates could take place. One goal of this study is to propose architectural solutions for water management in densely urbanised area but applied to neighbourhood presenting renovation potential. This study area presents lot of benefit to understand local water fluxes, interactions and management before extending it to the whole Brussels-Capital Region. The physical environment (topography and geology) and urbanisation layout are representative of a large part of Brussels. Lot of data are available to understand urban water-cycles (Forest Abbey, waste water treatment plant and stormwater drainage reservoir). 5.2. Methodology In this type of urbanized environment, all clues are highly valuable because urban water-cycles are very complex, hidden and likely to be changed with new construction, housing projects or sewage construction or renovation. Therfore, the first step is communicating regularly with local and regional authorities to be aware of new flood events and

housing estate projects. An extra attention must be given to old citizens who keep the local memory of floodings. They lived through past events in their neighbourhood and often know it better than the local administration. Once the information exchange is guaranteed, data will be collected (or produced) by three specific analyses (historical, geological and urban landscape) but treated interdisciplinary in order to correspond to local and real water management issues. There are some examples of interdisciplinary analysis: (1) Floods in neighbourhood of Saint-Denis plain are apparently caused by underground water. Water comes trough basement walls and floor during rain. However, quick response to the rain makes think of probable run-off processes. Stable isotope analyses will be done to clarify water provenance. The area is known for numerous old water-courses and springs now hidden by urbanization. In this case, the historical approach will adequately supplement the isotopic analyses. The conclusions will be then extended to other areas with old water-courses and flooding problems. (2) The new stormwater drainage reservoir will normally reduce the flood occurrence in the valley but not on upstream catchment. Rainwater infiltration techniques are being developed troughout Europe but merely within new housing estates. A good knowledge of geo-environmental characteristics differing along the catchment area leads to develop these techniques without creating other floods problems in a challenging densely urban context. (3) Other compensatory techniques than infiltration process do exist. New rainwater channels and ponds could be created to differ flood peak and to weaken sewer network surcharge during rain event. As said before, historical context is important to choose appropriate technical choice regarding to social acceptance and localization relevance. The numerous old water-courses and springs in this area are determining elements that will guide architectural choices.

6. CONCLUSION The rainwater plan currently is subject to a revision for the next four-year plan. According to European obligations, the water management plan must be accompanied by an operational program of measurements before the end of 2012. In other words, it must be accompanied by privileged concrete actions which will be implemented thanks to various political levers (laws, grants, information, public investments) coordinated between them. The achievement of this proposed study on a micro-catchment of Brussel could contribute to the political and environmental debates which will lead to the establishment of these plans. But the continuation of this study depends on opportunities given by different authorities (local and regional).

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7. REFERENCES [1] J.-P. Goubert. La conquête de l’eau. L’avènement de la santé à l’âge industriel, Paris (1995). [2] I. Backouche. La trace du Fleuve. La Seine et Paris 1750-1850, EHESS (2000). [3] C. Deligne C., M. Dagenais M. and C. Poitras. Gérer l'eau en milieu urbain 1870-1970. Bruxelles-Montréal, regards croisés, dans S. Jaumain et P. Linteau (éds.), Vivre en ville. Bruxelles-Montréal 19e et 20e siècles, 169-202 (2006). [4] G. Billen, J. Garnier, C. Deligne et C. Billen, Estimates of early-industrial inputs of nutrients to river systems: implication for coastal eutrophication, The science of Total Environment, 243/244, 43-52 (1999). [5] C. Deligne. Bruxelles et sa rivière, Genèse d’un territoire urbain, Brepols, Turnhout (2003). [6] Bruxelles Environnement. Rapport sur les incidences environnementales du projet de Plan régional de lutte contre des inondations - Plan Pluie 2008-2011, Bruxelles (2008). [7] Bruxelles Environnement. Plan de gestion de l’eau – questions importantes, Bruxelles (2009). [8] K. De Bondt and P. Claeys. Capacités naturelles d’absorption de l’eau de pluie par les sols en Région de Bruxelles-Capitale, ESSC-DGLG, Vrije Universiteit Brussel, Brussels (2009). Unpublished. [9] V. Mahaut. L’eau et la ville, le temps de la réconciliation. Jardins d’orage et nouvelles rivières urbaines, PhD. thesis, Ecole polytechnique de Louvain, Université catholique de Louvain, Louvain-la-Neuve (2009). [10] V. Mahaut. Comparaison de mesures alternatives pour la gestion des eaux de pluie à l’échelle des parcelles, www.bruxellesenvironnement.be/outil_gestion_e au (2009). [11] V. Mahaut V. and A. De Herde. A prototype tool for the design and environmental comparison of source control devices for small-scale developments in Brussels, paper proceedings at the 10th International Symposium on Stochastic Hydraulics and the 5th International Conference on Water Resources and Environment Research (joint Water 2010 symposium), Québec (2010). [12] C. Deligne. Histoire longue et prospective environnementale. Le cas d’une rivière périurbaine (Maelbeek, Région bruxelloise), J. Burnouf et Ph. Leveau, (dir.), Pratiques sociales et hydrosystèmes fluviaux, lacustres et palustres des sociétés préindustrielles. (Les fleuves ont une histoire, 2), Actes du Colloque PEVS/SEDD, 8-10 avril 2002, Aix-en-Provence, Comité des Travaux Historiques et Scientifiques, (2004), 285-290. [13] A. Guillerme. Les temps de l’eau: la cite, l’eau et les techniques, Seyssel, Champ Vallon (1983).

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th

[14] F.L. Hooimeijer. The New Dutch Polder City, 11 International Conference on Urban Drainage, Edinburgh, Scotland, UK (2008).

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. ISBN xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

Field survey on water-saving efficiency of roof rainwater harvesting system in Taiwan RUEY-LUNG HWANG 1, HAN-HSI LIANG1, RUEI-LING CHEN2, SHIU-YA SHUE1 1

2

Department of Architecture, National United University, Miaoli, Taiwan Architecture and Building Research Institute, Ministry of Interior, Taipei, Taiwan

ABSTRACT: The implementation of Taiwan’s Green Building Rating System has led to a number of cases of established rainwater harvesting systems; however, the post-establishment evaluation of such systems has never been completed. This study conducted field surveys on 55 actual cases of rainwater harvest systems. It is found that all the investigated cases regularly maintain their rainwater harvesting systems without operational problems, and more than half of them expressed the setting up of rainwater harvest system contributes to a reduction in the use of tap water. The review on rationality of system design found that the combination of a rainwater collection area and storage tank volume of 37 cases of the total 55 investigated cases was reasonably designed. However, eight cases had their storage tank volume too large, while the storage tank volume of ten cases was too small. The rainwater substitution rate analysis found that the current approach can generally ensure the replacement rate of the rated cases. Nevertheless, contradictions do exist in some cases. Therefore, this study proposed a new approach that was able to determine the volume metric reliability of the cases, as well as diagnose its design rationality Keywords: rainwater harvest system, water-saving efficiency, green building

1. INTRODUCTION Rainwater harvesting is a technology to collect and store rainwater falling on roofs or paved ground surfaces into a tank for future use. Rainwater harvesting systems are a cost-effective solution for the collection and reuse of rainwater for flushing needs and garden. Since rainwater harvest system makes a significant saving in the use of potable water. The use of rainwater to supplement the potable water supply in Taiwan has been demonstrated to be practical and effective [1].Thus, Taiwan’s Green Building Rating System [2] regards the installation of a rainwater collection system as an important credit in its water resource indicators. According to the guideline of Taiwan’s Green Building Rating System, a building with more than 2 100m of green and garden is obliged to install a rainwater harvesting system as an alternative source for green and garden watering needs. The capacity of rainwater storage tank is regulated by Vs≧0.5*N*AG/100

(1) 3

where Vs is the capacity of storage tank in m AG is the area of green and garden, m2 N is a factor depending on the location in Taiwan When the storage tank capacity of designed rainwater harvest system fill in with the requirements, the building is granted 3 points, otherwise 2 points are deducted. Since the implementation of Taiwan’s Green Building Rating System in Taiwan, there have been a number of cases of buildings setting up a rainwater harvest system. This study presented the results from field survey and benefit analysis on such cases. Based on the results of this study, a new approach to

ranking the rainwater harvesting system rating method was proposed in order to improve the shortcomings of existing simple ranking approach.

2. RESEARCH METHOD 2.1. Investigation subjects The investigated subjects of this study were 55 cases of buildings with the rainwater harvest systems in central Taiwan. All the buildings have passed the certification of Taiwan’s Green Building Rating System. The 55 building cases are composed of 26 school buildings, 17 office buildings, two hospital buildings, two residential buildings, and eight other buildings. Figures 1 and 2 illustrate the summary of the designed rainwater collection area and rainwater storage tank volume against the area of green and garden requiring irrigation. 2.1. Questionnaire survey Presented in the format of a checklist, the questionnaire consisted of six questions that collected information on: Q1 Do you know whether your organization has set up a rainwater harvesting system: □ Yes □ No Q2 The use of collected rainwater: □ irrigation □ toilet flushing □ irrigation and toilet flushing □ other Q3 Is the current rainwater harvesting system working properly? : □ Yes □ No Q4 Is the rainwater harvesting system regularly maintained? : □ Yes □ No

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withdrawn after the rainfall has been added to the storage facility and spillage has been determined. The YBS rule assumes that the demand is withdrawn before spillage is determined. The YBS model was used in this study and its operation principles can be illustrated mathematically as

collection area (m²)

25000 20000 15000

Yt = Min (Dt , St-1) St = Min (St-1 + Qt – Yt , Ca) Qt= C× I ×Area

10000 5000 0 0

2000

4000

6000

8000

10000

12000

irrigation area (m²)

 

Figure 1 A scatter diagram of the rainwater collection area against the area of green and garden of investigated cases

  5000

storage capacity (m³)

4000 3000

(2) (3) (4)

where Dt is water demand at time t; St-1 and St are storage at the beginning of the th th t-1 and t time period, respectively; Qt is inflow during the tth time period; th Yt is release during the t time period; and Ca is storage capacity. The use of rainwater has been limited for irrigation of green and garden. Daily intervals are normally used in simulations of operations. Figure 3 shows the flowchart of simulation. The 15-year (from 1996 to 2009) historical rainfall records from Central Weather Bureau, Taiwan were input into the YBS model for long-term simulation of the operation of rainwater harvesting system. The performance of rainwater harvesting system is described in terms of volumetric reliability (Rv). It can be expressed as

2000

Rv = actual supply/demand

(5)

 

1000 0 0

2000

4000

6000

8000

10000

irrigation area(m²)

12000

 

Figure 2 A scatter diagram of the storage tank volume against the area of green and garden of investigated cases

Q5 Is the rainwater harvesting system equipped with a meter to monitor its effectiveness? : □ Yes □ No Q6 In your observations, is the tap water consumption of your organization reduced after the installation of the rainwater harvesting system? : □ Yes □ No □ Unknown. All questionnaires were filled out by the general directors of the investigated cases. A total of 40 valid questionnaires were recovered. 2.2. System simulation In a simulation analysis, the changes in storage content of a finite capacity are determined using a mass balance equation. The procedure takes into account the four key factors, relating to the amount of rain water supplied by designed water harvesting system: the quantity of rainfall, the rainwater collection area, the capacity of rainwater storage tank and the water demand. Two water release rules are considered, namely, YAS (yield after spillage) and YBS (yield before spillage). The YAS rule can be understood by considering that the demand is

2

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  Figure 3 The flowchart to simulate the operation of rainwater harvest system

3. RESULTS AND DISCUSSIONS 3.1 Results of questionnaire survey Figure 4 summarized the results from questionnaire survey. Although all the investigated cases had installed rainwater harvesting system, but five (12.5%) of the 40 general directors surveyed did

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not know their originations had installed the rainwater harvesting system (Q1). 18 (42.5%), 5 (12.5%) and 8 (20%) cases reuse the collected rainwater for irrigating, flushing needs or both, respectively (Q2). In most cases the rainwater harvesting systems were regularly maintained (Q4); however, the results of questionnaire survey also indicate that such systems in four cases have been out of service in less than 3 years after installation (Q3). Only six cases were found to have water meters to monitor the amount of collected and reused rainwater (Q5). However, 15 cases indicated that the rainwater co harvesting system make a contribution on reducing the consumption of tap water (Q6). There leaves 12 cases expressing that they did not know whether the rainwater harvesting made saving on tap water or not, as no water meter has been installed. Interestingly, in six cases with installed water meters, only three cases indicated that the rainwater collection system helped to reduce the consumption of tap water.

3.2 Optimal Sizing As a reference for engineers who are involved in the design of rainwater harvesting system to get the credit point, the manual for Green Buildings in Taiwan does not provide a comprehensive and detailed examination of the effects of major parameters and estimates of their optimal values. Figure 5 demonstrates the distribution of the rainwater storage tank volume against collection area of the 55 investigated cases. Figure 5 also depicts the optimal expansion pathway as well as the feasible limits in Taiwan, proposed by Liao [3]. As shown in Figure 5, it illustrates that the investigated cases seem not to be designed by following optimal expansion pathway: 37 (67%) cases fell within the range of feasible, while the remaining 18 (33%) cases were out of the feasible range. In the cases out of the feasible range, eight cases had their storage tank volume too big, and ten cases had too small storage tank volume. 3.3 Performance of system

40

number of cases

35

Figure 6 illustrates the volumetric reliability of investigated cases calculated from YBS model. Figure 6 deliberately distinguishes cases granted +3 credit point from those cases granted -2 credit point. It can be seen from the figure that the volumetric reliability of cases granted +3 credit points was generally higher than that of cases granted -2 credit points.

30 25 20 15 10 5

Q2

Q3

Q4

Q5

No

Unknow

Yes

No

Yes

No

Yes

No

Yes

Both

Flushing

Irrigation

No

Yes

Q1

Q6

Figure 4 Questionnaire survey results summary

volumetric reliability (%)

100%

0

80% 60% 40% 20%

40000

0%

collection area (m²)

35000

-3

30000 25000

-2

-1

0 1 credit point

2

3

4

Figure 6 Distributions of volumetric reliability against credit point of investigated cases

20000 15000

3.4 A proposed approach for ranking

10000 5000 0 0

1000

2000

storage tank capacity

3000

4000

(m3)

Figure 5 Scatter diagram of the rainwater storage tank volume against the rainwater collection area of the investigated cases

The current approach ranks the rainwater harvesting system by taking account of the volume of storage tank, without considering the impact of the rainwater collection area, leading to the two phenomena requiring improvement, as shown in Figure 6. First, the volumetric reliability of cases granted +3 point was not always higher than cases granted -2 point; second, cases of different volumetric reliability grant the same credit point. To solve this problem, this study proposed an alternative approach that replacing volume of storage tank in the

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

storage tank volumn (m³/m2 of green)

current approach with the volumetric reliability as criterion for ranking. By using the YBS model, this study simulated the the volumetric reliability in the cases of different combinations of rainwater collection areas and storage tank volumes, when using all collected rainwater for green and garden watering needs. The calculated results were as represented by the curves shown in Figure 7. In Figure 7, storage tank volume for per square meter of green and garden was used as the horizontal ordinate, while the rainwater collection area for per square meter of green and garden was used as the vertical ordinate. Hence, it is easy to depict the design conditions of the 55 investigated cases on the figure and to determine their corresponding volumetric reliability. In addition to rapidly learning the volumetric reliability of any case, Figure 7 can be used to help the engineers to diagnose whether the system was well designed or not. For example, the case labelled 3 with ☆ in Figure 7 has a storage capacity of 0.18m for per m2 of green. As can be seen from the figure 7, 3 even if its storage capacity is reduced to 0.06 m for per m2 of green, the volumetric reliability replacement rate remains unchanged. In other words, in this case the storage tank was overdesigned. In fact, 1/3 of the original designed capacity is enough to achieve the same performance of system. Take the cases labelled with ★ in Figure 7 as another example. The rainwater collection area for this case 2 2 is 2.43m /m of green, while the unit area/storage 2 tank volume is only 0.01m3/m of green. If the 2 storage tank volume is increased to 0.08m3/m of green, the volumetric reliability can be dramatically increased from 4% to 42%. 0.20

70% (5 point) 60% (4 point)

0.16

50% (3 point)

0.12 40% (2 point)

0.08

30% (1 point)

0.04

20% (0 point) 10% (‐1 point)

0.00 0.0

1.0 2.0 3.0 collection area (m²/m2 of green)

4.0

Figure 7 Distributions of investigated cases in the newly established rainwater replacement rate calculation diagram

4. CONCLUSIONS Based on the results of this study, it can be concluded that 1. Most cases reused the collected rainwater for green and garden irrigating, as compared with

4

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cases reusing the rainwater for toilet flushing. 2. Field survey found that the rainwater harvesting systems in the investigated cases were regularly maintained and made a significant saving of tap water. It is also found that a few investigated cases had their system out of service or did not know they had established rainwater harvesting system. 3. By checking whether the systems of investigated case were rationally designed or not, it found that 37 cases of the 55 investigated cases were fell in the feasible range. However, it was also found that eight cases had their storage tank overdesign, while ten cases had their storage tank under design. 4. The analysis of performance of rainwater harvesting system found that there was room for improvement of the current criterion of ranking by storage capacity. 5. This study proposed an alternative approach to rank the system by the volumetric reliability instead of storage capacity. The proposed approach not only can determine the performance of the system but also make a contribution on system diagnosis.

5. ACKNOWANGEMENTS We sincerely appreciate the Architecture and Building Research Institute (ABRI), Ministry of Interior, Taiwan for assistance in grant.

 

6. REFERENCES [1] C.H. Liaw, S.H. Chu, Y.L. Tsai, and W.Y. Chen (1997), Development of Urban Rainwater Cistern Systems Technology. Engineering Science and Technology Bulletin NSC 26:75-78. [2] ABRI (2000), Evaluation Manual for Green Buildings in Taiwan, Architecture and Building Research Institute(ABRI), Ministry of Interior, Taipei, Taiwan. [3] C.H. Liaw and Y.L. Tsai (2005), Optimum storage volume of rooftop rainwater harvesting system for domestic use, Journal of the American water resources association, Paper No. 03014: 901-912

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Analysis of Seasonal Differences in Microclimate Formed in a Local Small City of Paddy Field Areas A new approach using airborne remote sensing and CFD simulation Takashi ASAWA1, Akira HOYANO1, Tamon YOSHIDA2, Masahito TAKATA1 1

Tokyo Institute of Technology, Yokohama, Japan 2 PASCO Corporation, Tokyo, Japan

ABSTRACT: This paper examines the relationship between the seasonal land cover change and microclimate formed in a local small city of paddy field areas in Japan using airborne remote sensing data and CFD (Computational Fluid Dynamics) simulation. The land cover maps for three seasons, the 3D urban district model and the 3D surface temperature images are made using the airborne MSS (Multi-Spectral Scanner) data obtained in each season and GIS data in Tonami city, Toyama prefecture. These data are applied to the boundary conditions for the CFD simulation, and microclimate, including air current and air temperature distribution, are simulated for three seasons taking into account the seasonal land cover change. The simulation results are compared with the field measurement results for the microclimates in the site. These results quantitatively indicate that the control of microclimate by the paddy fields changes seasonally as its land cover changes through the year. In the summertime, the cooling effect of the paddy fields and the cool air current from the area contribute to the decrease in air temperature in the urbanized area. Keywords: remote sensing, microclimate, CFD, surface temperature, paddy field

1. INTRODUCTION A change in land cover distribution is one of the primary factors influencing the heat island effect in urbanized areas. The heat island effect has been observed not only in large cities but also in small cities of Japanese countryside. As urbanization progresses in a small city, housing development is sprawling to the rural surroundings, then the land cover changes from natural surfaces and vegetation to artificial materials including asphalt pavement and reinforced concrete buildings with high heat capacity. In order to establish countermeasures against the heat island effect, it is necessary to understand the characteristics of land covers and local microclimate formed in the locations and its surroundings. Tonami city, a local small city in Japan, is located in the Tonami plains where wide spread paddy fields cover most of the land surfaces. The Tonami urbanized area is surrounded by the paddy fields, so that the cooling effect of the paddy fields could be utilized for the mitigation of the heat island effect in summertime [1] [2]. Besides, there is frequent change of land cover annually on the paddy fields. The land cover of croplands in the study site, which is water in springtime due to the irrigation, becomes green due to the growth of rice plants during summertime. In addition, it is covered with snow in wintertime. Therefore, the annual land cover change should be examined. In the previous study, the authors’ group implemented the analysis of nocturnal cold-air currents formed in urban neighbouring hills and forests using airborne remote sensing data and CFD

simulation [3]. The present study applies this analysis method. The purpose of the present study is to clarify the relationship between the annual land cover change of the paddy fields and the seasonal characteristics of microclimate formed in the Tonami urbanized areas using airborne remote sensing data and CFD simulation.

2. OUTLINE OF THE ANALYSIS 2.1. Analysis steps Firstly, the method to analyze microclimate is developed by using surface temperature distribution derived from the airborne multi-spectral scanner (MSS) data as a thermal boundary condition for CFD simulation. At this process, the surface temperature data are put on the 3D GIS data of the region, and then the 3D surface temperature images are completed. Secondly, the land cover and surface temperature distribution are analyzed by the 3D surface temperature images for each season. Finally, the effects of the land cover of the paddy fields on the microclimate are examined by using the CFD simulation results and field measurement results. 2.2. Airborne MSS data Observation by airborne MSS was performed in order to generate the land cover maps and surface temperature images of the Tonami plains, Japan for May and July of 2002, winter of 2006 both in daytime and in nighttime [4]. The two observation altitudes were set; course 1 for high altitude was 6,000 m, which allowed observation of the entire Tonami planes, and course 2 for low altitude was 1,500 m, which allowed observation of detailed ground surface

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information. Spatial resolutions on ground were 8.0m and 2.0m respectively. Figure 1 shows the observation courses. Table 1 shows the observation date and time for each season and Table 2 shows the Specification of the MSS data. Course1 (high) Course2 (low)

3. METHOD FOR ANALYZING MICROCLIMATE 3.1. Generation of the 3D urban district model The 3D urban district model was made by combining the GIS data of this region and the land cover maps (2m resolution) generated from the MSS data (Figure 2). The building models were made by putting building height information (multiplying stories by floor height) onto the building 2D polygon of the GIS data. The two types of building structure were set; one was wooden structure and the other was reinforced concrete structure. The tree models were generated by putting tree height information onto the tree distribution derived from the land cover maps. The three types of tree height, obtained from field measurement in this region, were set to the tree models. The building and tree models were put on the land cover maps, and the 3D urban district model was completed. 3.2. Generation of the 3D surface temperature image

Figure 1: Observation course of the airborne MSS Table 1: Observation date and time for each season

Date

Spring daytime

Spring Summer nighttime daytime

Summer nighttime

Winter daytime

Winter nighttime

2002/5/25

2002/5/21

2002/7/26

2006/2/22

2006/2/21

2002/7/25

Couse1 11:30-11:45 20:28-20:40 12:00-12:12 20:07-20:20 12:29-12:49 19:02-19:15 Course2 12:09-12:24 19:43-19:54 12:33-12:42 19:19-19:30 13:34-13:48 18:28-18:40

Table 2: Specification of the MSS data Spring and Summer Winter Wave Wave Band length(nm) length(nm) 1 459～489 1 459～489 2 542～564 2 551～579 3 586～614 3 586～614 4 655～679 4 655～679 5 683～713 5 825～871 6 738～768 6 976～1114 7 825～871 7 1026～1166 8 976～1114 8 1229～1375 9 1430～1570 9 1430～1570 10 1582～1666 10 1583～1695 11 6675～11815 11 6675～11815 12 10105～13525 12 10105～13525

The surface temperature images, generated from the MSS data, were put onto building roofs and ground of the 3D urban district model. The surface temperatures of building walls cannot be obtained from the MSS data, so that the wall temperatures were calculated by the 3D CAD-based thermal environment simulator, which was developed by the authors’ group [5]. The temperature of tree’s crown was determined by the vegetative (tree) coverage area of the surface temperature images. By these processes, the 3D surface temperature images for each season were completed (Figure 2).

Band

2.3. Generation of land cover maps In advance of the analysis of the land cover distribution, rectification and the land cover classification were conducted using the airborne MSS and GIS data. First of all, rectification was conducted by a second-order polynomial transformation using the airborne MSS data, and GIS data drawn on a scale of 1 to 5000. Extracting a small area from rectified MSS data, 6 items of polygon were created for signature, supervised classification was implemented. Considering the land cover change, the land cover maps including vegetative area were generated.

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Figure 2: Generation of the 3D urban district model and 3D surface temperature simage

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3.3. CFD simulation The subject area for the microclimate analysis using CFD simulation includes the Tonami urbanized area and its surrounding paddy fields. This subject area includes the field measurement positions for microclimates conducted in the summertime so that these data can be compared each other (Figure 3). The 3D surface temperature images generated in the previous step were used for the thermal boundary conditions (input data) for the CFD simulation, and then wind environment and air temperature distribution in the subject area were calculated. Three-dimensional turbulent airflow is given by Reynolds averaged Navier-Stokes equations (RANS). The governing flow equations are solved with the SIMPLE algorithm. A numerical scheme (QUICK) was used for pressure correction in solving the governing equations. The standard k- ԑ model was used for the turbulence model and the boussinesq approximation was used for the buoyancy-driven flow. Table 3 shows the details of the CFD simulation. Figure 4 illustrates the 3D model for the CFD simulation. Inflow air temperature and velocity were set using the AMeDAS (Automated Meteorological Data Acquisition System) data at Tonami city, where the weather station is located on the paddy field area. The CFD simulation was conducted for three seasons.

Figure 3: Subject area for the microclimate analysis using CFD simulation (including the field measurement points)

Figure 4: 3D model for CFD simulation (The wind direction is for the case of daytime in the summer and nighttime in the spring.)

4. RESULTS AND DISCUSSIONS 4.1. Comparison between the simulation result and observation result Figure 5 shows the comparison in air temperature and wind velocity distribution along a wide street between the CFD simulation result and field measurement result in the summertime. The field measurement was conducted along the street from the paddy fields to the urbanized area in the summer of 2004. The simulation result of wind velocity indicates that the wind velocity decreases gradually from the open paddy fields into the inside of the urbanized area. The difference in wind velocity between the inside and outside of the urbanized area is approximately 2 m/s. The simulation result of air temperature indicates that air current with lower temperature (cool air current) flows from the paddy field into the urbanized area along the street, and it reaches to approximately 400m inside from the edge of the urbanized area. The observation results of wind velocity and air temperature show the same distribution as the simulation results. Therefore it is confirms that the CFD simulation result is appropriate for the discussion.

Table 3: Details of the CFD simulation Dimension

2050m(X) x 895m(Y) x 100m(Z)

Grid number

1513 (X) x 895 (Y) x 43 (Z)

Minimum grid size

1m (for X and Y), 0.5m (for Z)

Turbulence model

Standard K-ԑ model

Solid surface

Log law for smooth surface Convective heat transfer coefficient 11.6W/m2K

Top and sides of

Free-slip

simulation domain Inflow boundary

Power law (power index 0.15) Wind velocity and temperature at the standard position are derived from Tonami AMeDAS data.

Outflow boundary

Free

Inflow wind direction

(1) Daytime in the summer: ENE (2) Nighttime in the spring: ENE (3) Daytime in the summer: SSW

Figure 5: Comparison between the simulation result and observation result (Summer, daytime)

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4.2. Simulation results for each season The CFD simulation was conducted for three cases taking into account the characteristics of land covers and surface temperature distributions; (1) Daytime in the summer, (2) Night time in the spring, (3) Daytime in the winter. Figure 6-8 show the 3D surface temperature images, the CFD simulation results of the air temperature distribution and wind velocity for each case. (1) Daytime in the summer The land cover of the paddy fields around the urbanized area is green due to the growth of rice plants. The surface temperature distribution image indicates that the surface temperatures of the paddy fields score much lower than the air temperature and approximately 30C lower than the asphalt paved ground in the urbanized area. The simulation result of air temperature distribution shows that the air temperature in the central urbanized area is much higher than that in the windward paddy fields, it is confirmed that the heat island effect occurs. The cool air current from the windward paddy fields flows into the urbanized area along the wide street and contributes to decreasing the air temperature in the urbanized area. However, the cool air current does not go over the cross road at the center of the urbanized area. The air temperature increases at the leeward of buildings and narrow streets where the air current stagnates and the surface temperatures of the space increase.

(2) Night time in the spring The land cover of the paddy fields is water in springtime due to the irrigation, so the urbanized area is surrounded by the water fields. The averaged surface temperature of the paddy fields is approximately 18C, only 3C lower than that of the asphalt pavement in the urbanized area, due to high heat capacity of water and its solar heat storage during the daytime. The difference in air temperature between the paddy fields and urbanized area is small as well as the surface temperatures.

(a)

Surface temperature distribution (generated from the MSS data)

(b)

(a)

Air temperature distribution (at a height of 2 m)

Surface temperature distribution (generated from the MSS data)

(c) Profile along the wide street Figure 7: Simulation results (Spring, nighttime)

(b)

Air temperature distribution (at a height of 2 m)

Figure 6: Simulation results (Summer, daytime)

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(3) Daytime in the winter In this season, the main wind direction over this region is south-west. The wind velocity in the paddy fields is approximately 3 m/s. The inflow air current into the urbanized area is blocked by the windward buildings and wind break forests situated on the

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

southern edge of the area, so that the wind velocity in most of the urbanized area is under 1.5 m/s. The land cover of the paddy fields is snow, and the surface temperature is approximately 20C lower than that in the urbanized area. The difference in air temperature between the paddy fields and the urbanized area is 2C; the heat island effect is confirmed in this season as well as the summer. Solar altitude is lower than that in the summer, so that the southern walls of the buildings receive large amount of solar radiation and its surface temperatures increase. The air temperatures around the buildings, therefore, increase. This is characteristic of the microclimate formed in this season.

(a)

Surface temperature distribution (generated from the MSS data)

These results indicate that the control of microclimate by the paddy fields changes seasonally as its land cover changes through the year.

5. CONCLUSION This paper presents the method to analyse microclimate in a local small town of paddy field areas using airborne MSS data and CFD simulation. The 3D urban district model and 3D surface temperature image were generated by combining the MSS data and GIS data in Tonami city. The relationships between the land covers of the paddy fields and microclimate formed inside and outside of the Tonami urbanized area were analysed using the 3D surface temperature image and CFD simulation for three seasons taking into account the seasonal land cover change. These results quantitatively indicate that the control of microclimate by the paddy field changes seasonally as its land cover changes through the year. In the summertime, the cooling effect of the paddy fields and the cool air current from the area contributed to the decrease in the air temperature in the urbanized area. In the spring, the difference in air temperature at nighttime between the paddy fields and urbanized area was small as well as the surface temperature, due to high heat capacity of irrigated water on the paddy fields. In the winter, the air temperature in the urbanized area was much higher than that in the paddy fields covered with snow, so that the heat island effect was confirmed.

6. REFERENCES

(b)

Air temperature distribution (at a height of 2 m)

[1] H. Yamada (1993), J. Jap. Inst. Landscape Architect, 56(5), pp.331-336. (In Japanese with English Abstract) [2] M. Yokohari (1998), J. Jap. Inst. Landscape Architect, 61(5), pp.731-736 (In Japanese with English Abstract) [3] A. Hoyano, J. He and H. Kita (2007), J. of The Remote Sensing Society of Japan, 27(5), pp.445455. (In Japanese with English Abstract) [4] A. Murakami, A. Hoyano and K. Kim (2007), Proc. of IGARSS 2007, 1786-1789. [5] T. Asawa, H. Hoyano and K. Nakaohkubo (2008), Building and Environment, 43, pp. 21122123.

(c) Profile along the wide street Figure 8: Simulation results (Winter, daytime)

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Rethinking the Green Roof. A proposal of Grey Water Phytodepuration System. Alberto Gómez González1, Inmaculada Morgado Baca1; Mariana Chanampa1, César Bedoya Frutos1, Consuelo Acha Román1, Javier Neila González1, 1

Universidad Politécnica de Madrid. Department of Construction and Technology in Architecture. ABIO-UPM Research Group (Bioclimatic Architecture in a Sustainable Environment) Corresponding author: [email protected]

ABSTRACT: The proposal is based on the need of rethinking the traditional building typologies and the opportunity to transform the water consumption patterns in our cities. According to the Spanish National Statistic Institute, Spain has an average water domestic consumption of 167 litres per person per day. Wash-basins and showers represent the highest values of 60 litres per person per day; while each inhabitant spends daily 45 litres by flushing the toilet. This implies a daily unload to the public sewerage system of 105 litres per inhabitant; more than a 60% of the total consumption. Furthermore, it is important to reconsider new ways of water reuse, especially in countries with low rainfall levels, like Spain. Because of that, the proposal researches the possibility of grey water management, associated with the development of new flat green roofs systems. It has been designed an industrialized prototype, which helps to reduce the main problems of traditional reed bed systems, such as their large dimensions, high weight and the compaction of the substrate by the roots. In this way it has been improved a system which optimizes the design of traditional channels, improving the contact between bacteria, roots and water. In the second part of the study, it has been analyzed the impact of its integration in urban environments, studying the estimated drinkable water savings, by reusing cleaned grey water in flushing toilets and irrigation. The theoretical behaviours study, in a medium density district of Madrid, has demonstrated that these strategies can save more than a 40% of the currently potable water consumes. Keywords: grey water reuse, phytodepuration, water management benefits, green roofs

1. INTRODUCTION The research has been developed in the frame of the subproject 10-Optimization Systems for Efficient Behaviour in Housing, belonging to the Strategic and Singular Project INVISO (Industrialization of Sustainable Housing). Developed since 2007, it has had four main phases, with the aim of designing industrialized prototypes associated with water saving systems. These phases are: 1. Cataloguing phase. There have been analysed and classified 166 strategies that nowadays are used in sustainable water management. They have been organized in the next categories of study: Rainwater, water consumption reduction, irrigation, grey water, waste water and water quality. 2. Selection phase. Each strategy has been described in detail, through analytical and graphical parameters, in order to define their level of Sustainability, Innovation and Functionality. As result of the strategies comparison, grey water treatments have been determined as the ones with greater potential development in industrialized housing field. Their application supposes important drinkable water saving, good possibilities of spatial innovation and relative easy application in housing. 3. Development of a phytodepuration system for grey water reuse. Although these systems are normally used in communities with large free land extensions; the development of the proposed strategy tries to adapt traditional systems into industrialized modular products, which can be applied in urban building roofs or gardens.

4. Prototype construction and monitoring. A first prototype of the industrialized phytodepuration system will be built on the roof of an experimental house in the village of Tembleque, close to the city of Toledo (Spain), funded by a private society.

2. GREY WATER REUSE According to the National Statistic Institute of Spain (INE 2005) [1], this country has an average drinking water consumption of 167 litres per person per day. Wash-basins and showers represent the highest values of 60 litres per person per day; while each inhabitant spends daily 45 litres by flushing the toilet (Table 1). It implies that practically the both uses together suppose the daily unload of 105 litres per person to the public sewerage system. These levels suggest that it is necessary to reconsider new ways of water reuse, especially in countries with low rainfall levels, like Spain [2]. Also, if water saving strategies [3] are using associated to water reuse systems, the levels of water consumption per inhabitant could be reduced in more than a 60%. 2.1. Definition of grey water Some authors define grey water as wastewater without any input from toilets, which so generally includes sources from baths, showers and basins, washing machines, dishwashers and kitchen sinks [4]. Meanwhile, other authors define grey water as the low polluted waste water from bath uses and washers [5].

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If Kitchen sink load is being included as grey water, the Biological Oxygen Demand (BOD) and the Phosphorus levels are increasing at similar levels as the WC loads ones [6]. Also, the suspended solids levels are higher and hardly controllable. Because of that, the proposed system will consider only grey water as the product of showers, baths, bidets and washbasins.

Because of that, the proposal is focused in two main actions to adopt. First of all, the incorporation of grey water systems that allows the separated conduction from black water. Also, the rethinking of new grey water treatment systems, will be focused on district scales, instead of urban ones; taking advantage of the large surface of flat roofs existent in these medium and high density areas.

Table 1: Average water consumption values in Spain (l/person day). Source: INE [1], ECODES [3], (estimated water consumption values, associated to the application of water saving strategies). *source: grey water, washingmachine included

3.3. Case Study

INE

ECODES

Shower/bath, bidet, washbasin Toilet

60

46

45

16

Washing machine

33

18

Cooking / drinking Cleaning Grey water Total water consumption

19 10 60 /93*

13 7 46/64*

167

100

3. APPROACH 3.1. Spanish Urban Context The population distribution of the Spanish cities differs markedly from the most of the Occidental European countries; mainly from these like United Kingdom or Central Europe, where it has been developed great amount of reed bed systems. The population density in Spain is 91,4 2 inhabitants per km [7]; while other countries with similar dimensions, reach values of 250 inhabitants 2 2 per km (Germany) or 243 inhabitants per km (United Kingdom). Unlike these European countries, the Spanish population is focused in medium and large cities, distributed on seaside and metropolitan valley areas that are densely populated. Also, there are some metropolitan interior areas, like Madrid, Zaragoza, Córdoba or Valladolid. This territorial organization concentrates the 45% of the population in only 7 provinces. Geographical, climatic and sociological condition, make the Spanish cities denser than the average European ones. 3.2. The Metropolitan Area of Madrid The Metropolitan Area of Madrid is the fourth larger in the European Union, after Paris, London and Essen-Düsseldorf [8]. It had an important development since the sixties, which implied the growth of the peripheral cities with high and medium density models. This urban planning promoted the construction of high multi-storey housing buildings, but with the lack of public green spaces. Respect to the urban water management, many centralized wastewater treatment stations were built in outer parts of the city. But nowadays, the continuously growth has contributed to their incorporation in the urban space and to the overload of the installations.

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The city of Alcalá de Henares, is situated in the Metropolitan Area of Madrid, being a good example of the urban growth that was developed in the sixties and seventies years. A high density area of this city has been selected, in order to study the benefits of the industrialized phytodepuration system associated to the existing large flat roof surface (Fig.1).

Figure 1: Proposal area.

The studied area is bounded by the Avenida Complutense with the Ribera, Murillo, Caballería Española, Juan de Arellano and Manuel Azaña streets. It was built in the seventies, and it is formed by two dwelling blocks organized with a central volume, this one with tertiary use. Each dwelling has a commercial level plus seven storeys, and a storage basement underground. The dwellings have a 2 medium built surface of 100-130 m , organized in four bedrooms and two bathrooms. According to the Comunidad de Madrid legislation [9], it has been calculated an average of 3 equivalent inhabitants per dwelling. Respect to the central volume, it is used as shopping centre. It has a main commercial floor and another basement used as an underground car park. 2 This building has a large flat roof of 4.690 m , mainly free and without any use, except a small space, used as installations room (Table 2). Table 2: Flat roof surfaces in each building (m2).

Block A Roof surface 2 4.300 (m )

Block B Roof surface 2 4.400 (m )

Commercial building Roof surface 2 4.690 (m )

4. STRATEGY The opportunity of reusing the large roof surface of the central building has been considered, in order to improve the water treatment management strategies at district scale; at the same time to improve the landscape environment of the area. Because of that, the proposal will take advantage of the lack of direct contact between inhabitants and grey water on the roof; but also it configures a new urban landscape to the surrounded dwellings.

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On the other hand, the previous design of the dwelling buildings has helped to diminish the works on the existing dwellings. The two bathrooms of each dwelling are sharing the same technical wall, allowing to reducing the length of the new grey water pipeline, diminishing the cost of the work. 4.1. Industrialized Phytodepuration system The industrialized phytodepuration system aims to purify the grey water, in order to the reuse in irrigation and flushing toilets. In this way, it is possible to diminish the potable water consumption and the volume of water that daily overloads the urban wastewater treatment plants. Because of that, it has been proposed a centralized system, associated to the medium and small scales, in order to its easily incorporation to the existing urban contexts. The following process has been studied: The grey water from each apartment is conducted by an independent pipeline, separating the water produced in the showers, washbasins and bidets. This water is pre-filtered by a centralized unit, in order to remove suspended solids; and then it is stored in a preliminary cistern. Daily , water is pumped to a main centralized tank, and from there it is pumped again to the industrialized phytodepuration tanks, where the macrophytes are floating. The tanks are organized on the flat roof, making a zig-zag shape, in order to optimize the space of this building area. The design of the modular tanks, allows many distribution combinations; at the same way it makes possible to build a circuit, in which the water flows. The optimization of the tank dimensions and the circuit design, contributes to increase the contact between rhyzosphere and grey water. In this way, the aerobic bacteria, which are responsible of the purifying, are developed on the roots, so the increase of contact between roots and water allows to improving the efficiency of the system. It has been estimated a necessary period to purify the water of a week. After this period, the cleaned water is circulated to the storage cistern, waiting to be reused in flushing toilets or irrigation the rest of the green roof and the nearby green public space. Then, the purified water is stored again in another centralized cistern, waiting to be reused in flushing toilets or irrigation of the rest of the roof and the nearby green public space (Fig. 2).

Figure 2: Working principle.

4.2. Dual plumbing The installation of the dual plumbing is necessary, in order to collect the grey water and separate it from the black water from toilets and kitchen sinks. The grouping of bathrooms in the existing dwellings diminishes the necessity of large pipelines construction, minimizing the economic and environmental costs of the project. If the water from washing machine is collected, it is recommended to place it also in the bathroom, in order to diminish the length of the new grey water pipeline. Once collected in each dwelling, grey water is conduced to a pre-filtration system, where solid particles are taken out. This pre-filtration system can be individual or collective, but it is recommended that it will be collective, in order to facilitate the maintenance and to diminish costs. Pre-cleaned water is later stored in a preliminary tank, where should not be more than 24 hours, in order to avoid bacteria development. Each doorway has a preliminary cistern, from where water is then pumped to the centralized deposits, one per block. These centralized deposits are placed in the basement of the central commercial building. The daily pumped water for the whole complex depends on the source of grey water. Due to the great amount of equivalent inhabitants (1.680), and the minimum daily consumption of 46 litres per person per day, it has been estimated a daily grey water consume of 77.280 litres. Because of that, it is necessary that the water will be pumped from the primary deposits, in a coordinated and alternately way; in order to diminish the volume of water that simultaneously comes to the centralized tank. 4.3. Phytodepuration area The main innovation has being developed in relation with the phytodepuration area. As traditional wetlands are so large that is not possible to define the tour wastewater does, the strategy proposes to reduce drastically the required water treatment surface. Because of that, the industrialized tanks have been designed, with the aim of controlling the water circulations, by reducing the width and height of each tank. Subsurface reed beds have normally a 4.00 m width [10], and are normally disposed linearly. However, the developed strategy will reduce the width to 1.50 m, in order to increase contact between roots, bacteria and water, optimizing the system and reducing the space needed. Also, the maximal length of the tank is 10 m, in order to avoid joints, but facilitating its portability and the transport of the system. In order to diminish the roots growth in the connection pipelines between industrialized tanks, three different areas have been design in each tank. The central area is the largest and is where the macrophytes float; while the end sides are free of roots, in order to facilitate the water circulation. Also, a platform over the tank has been projected, providing to the system an air chamber which will avoid disgusting smell. A layer of gravel is disposed

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over this platform, in order to protect the water from the exterior pollution components, sheets or insects. Respect to the problem of weight, the height of the water will be maximal 40 cm, enough to the development of the macrophytes selected. Also, the reduction of treatment surface, contributes to diminish the weight of the new roof in comparison with the traditional reed beds (Fig. 3).

4.5. Storage system The storage system has been organized in two centralized deposits where the clean water is stored, and from where is again pumped to the storage tank of each doorway. This cleaned water can be reused in flushing toilets, in irrigating green public spaces or in street flushing.

5. WATER SAVING STUDY 5.1. Water savings

Figure 3: Industrialized phytodepuration components.

4.4. Macrophytes in flotation The macrophytes in flotation filters (FMF) have been firstly developed by the Grupo de Agroenergética of the Universidad Politécnica de Madrid, leaded by the Professor J. Fernández [10]. The technical consist in combining the benefits of emergent and floating plants. The emergent plants, like Praghmites or Typhas, have an important rhyzosphere volume, so when they have growth enough, they are incorporated to the aquatic medium by the used of buoys. Because of the rizosphere volume is greater than the natural aquatic plants, the volume of aerobic bacteria increases and with it the system efficiency. Also, roots are floating, which avoids the traditional problems associated to the compaction of the substrate. The innovation relative with the FMF, consists in the incorporation of a transitivity platform over the tank. This platform contributes to the macrophytes support, avoiding the necessity of buoys. It is supported by two lateral tank reinforcements and transversal polypropylene cells transversally disposed. These cells contribute to the oxygenation of the water which passes through them (Fig. 4).

It has been studied many different situations, in order to quantify the impact of the use of phytodepuration systems in flat green roofs. The selected parameters of study depend on the source of the grey water and the combination with other complementary actions, associated to the water consumption reduction. The first hypothesis A, has only considered the incorporation of the industrialized phytodepuration system; the hypothesis B, includes also the replacement of low consumption toilets; and the hypothesis C, includes also the use of different strategies of water saving, such as aerated taps, thermostatic taps, low power washers, etc. [3]. Each hypothesis has been studied according to two different sources of grey water. Firstly, it was only included the water produced in showers, baths, bidets and washbasins (Table 3); and then the water from washing machines was included (Table 4). 1.680 total inhabitants has been estimated in the area, according to the parameters of the Comunidad de Madrid official laws. Table 3: Water produced in shower, bath, bidet and washbasin. Percentages of daily water reuse

Hypothesis A_ only phytodepuration Grey water produced (l/inh.eq) 60 Total litres 100.800 Total cleaned water 70.560 100,00 % Wc flushing (l/inhab.eq) 45 Total litres 75.600 107,14 % Need extra water (litres) -5.040 -6,67 % Hypothesis B_ Included replacement of low consumption toilets Grey water produced (l/inh.eq) 60 Total litres 100.800 Total cleaned water 70.560 100,00 % Wc flushing (l/inhab.eq) 16 Total litres 28.880 38,10 % Extra for irrigation reuse (litres) 43.680 61,90 % Hypothesis C_ With strategies of water reduction consumption

Figure 4: Details of the industrialized phytodepuration tanks. 01. Floating macrophytes 02. Platform cover 03.Gravel 04. Industrialized tank 05. Reinforced support for the platform cover 06. Grey water pipeline 07. Stainless steel mesh to separate phytodepuration area and roots protected area 08. Water circulation area protected from roots 09. Stainless steel frame 10. Registering cover 11. Outflow pipeline 12. Phytodepuration area 13. Rhyzosphere area

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Grey water produced (l/inh.eq) Total litres Total cleaned water Wc flushing (l/inhab.eq) Total litres Extra for irrigation reuse (litres)

46 77.280 54.096 100,00 % 16 28.880 49,69 % 27.216 50,31 %

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Table 4:Water produced in shower, bath, bidet, washbasin and washing machine. Percentages of daily water reuse

Hypothesis A_ only phytodepuration Percentages of daily water reuse Grey water produced(l/inhab.eq) 93 Total litres 156.240 Total cleaned water 109.368 100,00 % Wc flushing (l/inhab.eq) 45 Total litres 75.600 45,33 % Need extra water (litres) 33.768 44,67 % Hypothesis B_ Included replacement of low consumption toilets

Figure 6: Phytodepuration in flat roofs. Proposal view.

Percentages of daily water reuse

6. MONITORING

Grey water produced(l/inhab.eq) 93 Total litres 156.240 Total cleaned water 109.368 100,00 % Wc flushing (l/inhab.eq) 16 Total litres 26.880 24,58 % Extra for irrigation reuse (litres) 82.488 75,42 % Hypothesis C_ With strategies of water reduction consumption

In parallel to the study of water savings impact in urban areas by using phytodepuration systems in flat roofs; two scaled prototypes will be built and monitored. A first application has been developed in the ground of the Aula de Educaciob Ambiental of Pozuelo de Alarcón, by the biologist Óscar Domínguez.

Percentages of daily water reuse Grey water produced(l/inhab.eq) 64 Total litres 107.520 Total cleaned water 75.264 100,00 % Wc flushing (l/inhab.eq) 16 Total litres 26.880 35,71 % Extra for irrigation reuse (litres) 48.384 64,29 % Empirical data observed by the Universidad Politécnica en Madrid in other experimental phytodepuration prototypes, which has been built too in the same climatic areas as the proposal, shows that it should be considered 30% water loses by evaporation and possible fails of the pipelines. These percentages have been considered in the analytical study, reducing the total grey water volume that could be cleaned, to be reused in irrigation and flushing toilets. 5.2. Economical impact This industrialized and modular system can be used not only in roofs, but also in gardens or parks. Due to its dimensions optimization, the economic and environmental costs associated to the use of materials were considerably diminished. Also, the industrialization provides important benefits in relation with construction and deconstruction periods. Respect to the economic costs, it has been estimated that a system in a single house with 5 equivalent inhabitants is around 1.200 euros/inhabitant, including installations and construction. But also, it has been estimated that the use in a centralized district context, could diminish the price per inhabitant, around a 40% less.

Figure 7: Prototype built in the ground. Aula de Educación Ambiental of Pozuelo de Alarcón, by Ó.Domínguez

On the other hand, the first prototype on a flat roof will be constructed by the UPM during 2011, in a single dwelling for 5 inhabitants, in the city of Tembleque, Toledo (Spain). The technical project of the second prototype has been approved, and the works has been started in November 2010. In this case, water will be reused to irrigate the garden and to flush toilets of the house. The prototype will also have a complementary connexion to the primary potable water net, in order to avoid problems when grey water is not enough produced. During the second half of 2011, this prototype will be concluded, and it will be monitored in order to analyze the quality of cleaned water, according to the parameters of the law R.D. 1620/2007, which regulates the quality of the reused water in function of the different uses. The analysis of cleaned water will be compared in the two prototypes; which also will allow the study of the relation between climatic parameters (temperature, wind influence, etc) and the position of the prototypes in the building (ground and roof).

7. CONCLUSIONS According to the objectives of the study; in the first part of the project, an industrialized prototype of grey water phytodepuration has been designed, adapted to the constructive and water management requirements of flat roofs in medium density cities.

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By the optimization of the channels design, the construction of the industrialized prototype allows the reduction of treatment surface required in traditional reed bed systems. In comparison with the FMF [12], the required surface for the industrialized system has been reduced in almost five times (Table 5). Table 5: Surface of phytodepuration, according to the current filters of macrophytes in flotation (FMF) in comparison with the estimation or required surface, using the industrialized phytodepuration system.

Conventional macrophytes in flotation filters(FMF) Total equivalent inhabitants 2 * m / equivalent inhabitant 2 total surface need (m ) Grey water circulation optimized

1.680 5 8.400

3

Total volume to be depurated (m ) 156,2 Industrialized tanks high (m) 0,5 2 Total daily surface need (m ) 312,5 Evaporation losses (%) 30 % Phytodepuration period 7 2 Total surface need (m ) 1.531,2 2 Total surface (included transivity areas) (m ) 1.840,0 On the other hand, after the analysis of the different hypothesis, it can be concluded that conversion of traditional flat roofs into grey water phytodepuration systems, can suppose important benefits associated to the urban water management. According to the different studied hypothesis, this system allows the reduction of potable water consumption, in uses that does not require it; meanwhile the volume circulated to urban wastewater treatment stations can be diminished in almost a 60%. If each hypothesis is being detailed analysed and compared with the current water consumes, it can be exposed the following estimations (Tables 6,7): Table 6: Water produced in washbasin and washing machine

shower,

bath,

bidet,

Hypothesis A_Only phytodepuration _The grey water produced is not enough to reuse the 100% in flushing toilets, but it is only necessary almost 7% more to cover all the demand. _The system will save 25% respect to the current water consumption. Hypothesis B_Use of the phytodepuration system with the replace of existing toilets for others of low consume _The strategy will save 34% respect to the current water consumption. _The combined strategy will save 27% respect to only replace the toilets for others of low consume. Hypothesis C_Use of the phytodepuration system, including strategies of water reduction consumption _The strategy will save 45% respect to the current water consumption. _The combined strategy will save 32% respect to apply only all the other water reduction consumption strategies.

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Table 7: Water produced in washbasin and washing machine

shower,

bath,

bidet,

Hypothesis A_ Only the phytodepuration system The strategy will save 39% respect to the current water consumption. Hypothesis B_Use of the phytodepuration system with the replace of existing toilets for others of low consume _The strategy will save 43% respect to the current water consumption. _The combined strategy will save 48% respect to replace only the toilets for others of low consume. Hypothesis C_Use of the phytodepuration system, including strategies of water reduction consumption _The strategy will save 59% respect to the current water consumption. _The combined strategy will save 67% respect to apply only all the other water reduction consumption strategies.

8. ACKNOWLEDGEMENTS The results presented here have been developed in the frame of the INVISO Project (Industrialization of Sustainable Housing), funded by the Spanish Ministry of Science and Technology.

9. REFERENCES [1] National Statistic Institut, (2005), Encuesta sobre suministro y tratamiento del agua. Madrid: INE. [2] Cabrera, E., (2007), La sequía en España. Directrices para minimizar su impacto. Madrid: Ministerio de Medio Ambiente. [3] ECODES, (2006), Proyecto Life Zaragoza, ciudad ahorradora. Zaragoza: Gob. de Aragón. [4] Eriksson, E. et al., (2002), Characteristics of grey wastewater. Urban Water, 4 (1), pp.85-104. [5] Nolde, E., (1999), Greywater reuse systems for toilet flushing in multi-storey buildings. Urban Water, 1, pp.275-284. [6] Butler, D. et al., (1995), Characterising the quantity and quality of domestic wastewater. Water Science and Technology, 31 (7),pp.13-24. [7] National Satistic Institut of Spain, (2008), Indicadores demográficos básicos. Madrid: INE. [8] Wendell, C., (2010), Demographia World Urban Areas: Population & Projections, 6 ed. [9] R.D. Normas aplicables al tratamiento de las aguas residuales urbanas. (2004), Madrid: Dirección General de Arquitectura. Com. Madrid. [10] Fernández, J., (2005), Filtros de macrofitas en flotación. Murcia: Ayuntamiento de Murcia.

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Measuring the effects of urban form on urban microclimate MATTHIAS IRGER1 1

Faculty of Built Environment, University of New South Wales, NSW, Australia; CSIRO, National Climate Adaptation Research Flagship, Urban Systems, Canberra, ACT, Australia

ABSTRACT: The current literature on the Urban Heat Island fails to adequately quantify the modifying effect of various elements of the urban form on the urban microclimate, in particular within the urban canopy layer at pedestrian level. The ongoing research compares urban form in relation to the thermal performance of precincts with the aim to quantify the contributions of various elements, such as vegetation, urban canyon geometry and orientation and urban surface characteristics, to microclimate alteration, in particular elevated urban temperatures. The study employs multi-spectral remote imaging to examine the spatial structure of thermal patterns in selected regions in Sydney. This data will be combined with ground-based measurements using the software ArcGIS for spatial analysis, data management, and mapping. Once the complex interplay between urban form and the urban microclimate is better understood, it would be possible to mitigate the effects of climate change, enhance human comfort and reduce CO2-emissions through urban design interventions that focus on the resilience of the built environment to the effects of urban warming. Keywords: Sustainable urban design, Urban microclimate, Urban Heat Island, Climate change adaptation, Remote sensing

1. INTRODUCTION For the first time in history, more than half of the world’s population now live in cities, which is expected to increase to two thirds by the middle of this century [1]. Australia is one of the most urbanized nations in the world, with the majority of residents living in its five largest cities [2]. Additionally, Australia has one of the highest immigration rates of all developed countries, leading to an almost doubling of its population within the next 50 years [3]. The process of urban settlement has profoundly impacted on the environment and dramatically changed the climatic conditions of previously rural regions. th In the early 19 century Luke Howard first recorded that urban areas tend to have higher average temperatures than their rural surroundings, a phenomenon later named the “Urban Heat Island” (UHI) effect [4]. The UHI can be experienced to a varying degree in every settlement and is attributed to gradual surface modifications, including the replacement of the natural vegetation with dark coloured surfaces, such as roads and roofs, which absorb large amounts of radiation during the day, and slowly emit the stored energy during the night [5, 6]. Oke (1973) has correlated the UHI intensity to the size of a cities’ population, importantly noting that cities in Europe feature a weaker UHI than those in the USA, which is likely due to morphological differences [7]. Precisely this disparity is of great importance, as its understanding could enable urban designers to advantageously manipulate the urban microclimate. Furthermore, it is argued that suburbs, which are

characteristic of Australian cities with relatively low population and dwelling densities, can support strong UHIs, given their particular urban form. While urban warming may be desirable in cold climates, in hot and arid regions it can present significant threats to human health, increase the  discomfort of people, reduce their efficiency, limit their enjoyment and use of their environment, impede on opportunities for active travel such as walking and cycling, and cause damage to the built environment [8]. In the course of recent heat waves in Australia, France, Russia and other countries, morgues exceeded capacity as mortality rates multiplied during prolonged extreme heat for several days [912]. As older people are more vulnerable to extreme heat events, a changing demographic profile with a doubling of people aged 65 years and over by the middle of the century will potentially expose large proportions of the population to discomfort and an elevated risk to their health during days with high temperatures and more frequent heat waves [13]. Despite some international climate change mitigation efforts, the world has already committed to a significant amount of global warming over the next decades and even centuries [14]. Already elevated temperatures attributed to the UHI will be further amplified by the effects of global warming [8]. Australia, with its extensive arid and semi-arid areas and high rainfall variability, is one of the countries most at risk from climate change [15]. Across the nation, warming of up to 2.0°C over the past 50 years has already been documented, with 2010 on track to become the hottest year ever recorded [16]. As economic growth centred in Asia continues to drive rapid greenhouse gas emissions significantly beyond those projected by the Intergovernmental

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Panel of Climate Change, this trend is projected to accelerate over the next century, leading to a further increase in average annual temperatures of 2.0°C above 1990 levels by 2030 [16, 17]. In response to the need to reduce greenhouse gas emissions and adapt to the effects of climate change, different forms of settlement patterns are being explored by the planning community. As articulated in many of the metropolitan plans for Australian cities, development policies aim to constrain the urban footprint by establishing urban growth boundaries and proposing a more compact settlement form with higher population and dwelling densities, particularly to reduce emissions from the transport sector [18, 19]. In practise, densification strategies have led to the simple reduction in plot sizes, while the long-term trend towards larger houses has continued, despite a trend to smaller household sizes [2, 20]. The owneroccupied detached house remains the signature of Australian cities, where outdoor areas are either paved over or non-existent, as developers seek to maximize the buildings footprint to meet perceived customer preference [20]. The marginalization of private outdoor areas combined with the absence of vegetation on public land have consequently created very dry urban areas featuring predominantly impervious surfaces, lack of natural shading and evapotranspiration, and a high degree of thermal mass. This urban form supports strong UHIs, in particular at street scale on pedestrian level, and inhibits sustainable design principles, such as natural daylight access, cross ventilation and ‘night-flush’ of buildings with cool air during the night. In combination with poor construction techniques and the lack of insulation, this has resulted in an increased reliance on technological appliances like air-conditioning to maintain human comfort levels leading to growing electricity demand. Additionally, the absence of urban design strategies to protect pedestrians from solar radiation and traffic have contributed to a further increase in car use, as temperatures in neighbourhoods have become too hot to walk or cycle. Thus, urban densification policies implemented as a strategy for climate change mitigation have conflicted with the goal they aim to achieve. The need to restructure Australia’s cities to accommodate significant population growth presents an opportunity to redevelop outdated building stock and disadvantageous urban from. It is therefore imperative to develop urban design guidelines with the focus on reducing the carbon footprint of new precincts, and to explore possible design interventions for existing suburbs, in order to minimize the adverse implications of urban warming due to the combined effects of climate change and the UHI. There is, however, a lack of knowledge in the urban design and planning community regarding the implications of different urban form characteristics and their impact on the urban microclimate, and thus on human comfort and energy consumption.

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2. LITERATURE REVIEW Over the decades, the field of urban climatology has produced a considerable volume of research with diverse focus and methodologies in various spatial and temporal scales. Since the 19th century, climatologists have been interested in the balance of energy fluxes within urban areas, and their difference to their rural surroundings [21]. Most early descriptive studies focused on individual climatic phenomena, comparing records of different weather stations in urban and rural areas, or applying city-wide automobile traverses [7, 22, 23]. Since the 1970’s significant progress has been made in understanding atmospheric processes, such as radiant energy budgets and the urban wind field [21]. The investigation into the causality of urban climate modifications was greatly facilitated by Oke’s (1987) differentiation between the Urban Canopy Layer (UCL), which extends from the surface to the roofs of buildings; and the Urban Boundary Layer (UBL), situated directly above [24]. 2.1. Urban form parameters The application of micrometeorological theory in diagnostic studies, exploring the spatial and temporal variability of the urban climate and its modification by isolated elements of the urban form, have led to the development of theoretical models of the urban energy balance [21, 22]. Simulative studies have identified the properties of the urban surface and the geometry of the urban canyon as the most influential factors for thermal modification of the urban climate [22, 25, 26]. The urban environment consist of multiple surfaces with material specific characteristics that govern the amount of absorbed and re-emitted longand short-wave radiation, thus each contributing in varying degrees to the urban energy balance [27]. Simulative studies of a typical U.S. city have shown that the combined effect of direct and indirect energy savings through an increase of the overall city-wide “albedo” - a surface’s ability to reflect incoming radiation - could lower the average urban air temperature by 5K, while reducing the energy demand for air-conditioning up to 40% [28]. The geometry of the urban canyon is defined as the ratio between the height of the canyons’ flanking buildings (H) and the width of the street (W), thus controlling the amount of solar radiation admitted into the canyon, radiative loss towards the sky, wind flow, and degree of air dispersion and ventilation [25, 29]. Additionally, the orientation of the urban canyon also affects the solar exposure of its vertical and horizontal surfaces, the degree of ventilation within the canyon and the overall wind conditions in the area [29]. While the H/W-ratio together with the length (L) of an urban canyon governs the quantity of low- and short-wave radiation accessible to increase air and surfaces temperatures and the degree of shade that is available to pedestrians and buildings during the day, it also controls the rate of a surface’s cooling at night [25]. The magnitude of this long-wave radiative

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loss has been found to be proportional to its “skyview factor”, which can be measured as the proportion of the viewing hemisphere that is occupied by the sky [29]. The H/W/L-ratio describes the “surface roughness” of the urban environment towards the sky, which affects the wind speed above roof level, the degree of air intermixing between UCL and UBL above, and the amount of shelter provided from strong winds [29]. Field and wind tunnel studies have shown that the geometry and orientation of urban canyons and the organization of buildings and streets within precincts can greatly affect air flow and ventilation in neighbourhoods [29, 30]. In his evaluation of the benefits of minimizing heat-gain in summer versus utilizing the UHI to save energy for heating in winter, while maximizing shelter from wind, dispersion of pollutants and daylight access, Oke (1988b) recommended H/W-ratios of 0.4 to 0.7 for North American cities at mid latitude. Further studies have demonstrated that trees and other vegetation significantly improve the urban climate due to the provision of shade and evaporative cooling, promote biodiversity and enhance urban air quality by reducing airborne pollutants [31-33]. Researchers have found that parks as well as green walls and roofs have the potential to lower the air temperature in their immediate surroundings in excess of 10K at street level, and demonstrated a noticeable cooling effect extending up to 1100 m in windward directions [27, 34-36]. On a larger scale, simulative studies have shown that a doubling of the average tree cover in North American cities could reduce the UHI by about 2K [28, 37]. The availability of moisture is another factor influencing the urban microclimate by cooling the air through evaporation of water and enabling evapotranspiration by plants [32, 36]. Modelling has suggested that an increase in the average moisture availability in North American cities from currently 15% of that in rural areas to 30% would result in a reduction of the UHI by 20% [32]. Other studies have identified anthropogenic heat release through vehicles, transport systems, airconditioning units and other human activities as major contributors to the elevation of urban temperatures [21]. These inputs can be considerable in compact city centres, while less significant in residential and suburban areas [21, 26, 38]. 2.2. Remote sensing The utilization of satellite based remote sensing has enabled the detection of urban surface heat islands (SUHI) on a city wide scale [39-43]. In their review of urban climate studies, which have applied thermal remote sensing before the year 2000, Voogt and Oke (2003) note: “While progress has been made, the thermal remote sensing of urban areas has been slow to advance beyond qualitative description of thermal patterns and simple correlations” [42]. Most studies appear to be limited by the application of general land-use data to describe the urban surface and their lack of

comprehensive urban form classifications. Additionally, the relatively low resolution of satellite imaging, especially in the thermal infrared spectrum, only provides averaged information of urban thermal patterns at a meso or macro scale, and fails to contribute to the causal exploration of urban microclimate modification. More recently, technological advances have enabled airborne remote sensing to detect SUHIs at a micro scale with a resolution of <1m. Stone and Rogers (2001) were amongst the first to employ highresolution airborne remote imaging in the city of Atlanta, concluding that low-density residential areas can emit a larger amount of thermal energy than more compact districts of the city [44]. Regrettably, this powerful method of data collection has not been widely utilized to examine the microclimate in urban areas. In summary, while the mechanisms influencing the urban climate are largely understood, current research fails to quantify the modifying effect of various elements of the urban form on the urban microclimate, in particular at neighbourhood scale and pedestrian level. Many descriptive studies are limited by a small sample size or poor spatial resolution and seldom go beyond urban-rural temperature comparisons. Advances in remote sensing technology have the potential to enable future analyses of the urban climate at an appropriate spatial resolution required to examine the microclimate at precinct and street scale, while at the same time supporting large sampling areas. The results of simulative studies need to be validated by empirical measurements and expanded to a wider geographical range. Importantly, their findings need to be translated into guidelines in order to increase their accessibility for urban design and planning professionals.

3. METHODOLOGY This new research aims to verify possible correlations between urban air and surface temperatures and different aspects of the urban form, in particular the urban canyon geometry, vegetation content within the built environment, surface characteristics of the urban structures and the street orientation within precincts, and seeks to quantify their relationship. This study employs airborne remote sensing to collect high-resolution information of urban surface temperature, vegetation content in precincts, soil moisture content, and geometry of the urban canyon, across the Sydney metropolitan region. This data will be supplemented and validated against simultaneously collected in-situ measurements of air temperature, long- and shortwave radiation and photography in selected case study areas located within the area covered by the aircraft. Using the software ArcGIS, this data will be assembled and geospatially analysed in combination with aerial photography, land-use and demographic data.

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3.1. Remote sensing There are three main advantages of employing airborne remote sensing: the first is the ability to cover a large number and diversity of urban precincts; secondly, recent technological improvements have lead to the development of various sensors with very high resolutions in the submeter range; and thirdly an array of different scanners can be utilized simultaneously in a single flight. The flight will be carried out with a small research aircraft that will encompass a course departing from Sydney airport, located at the coast to the city’s East, to the Western edge of the metropolitan region at Penrith, passing the North Shore area before returning the airport. This transect will provide a sufficiently large sampling area comprising a representative cross section of Sydney’s typical urban environments, while allowing for specific regional geographical features and the influence of the proximity to the ocean. In order to analyse the effect that different urban phenomena, such as parks, bodies of water or clusters of trees, have on the air temperature in their immediate surroundings and surrounding neighbourhood, a swath width of 2000m is considered to be the minimum. Initially, two flights are proposed: the first on a hot, clear day and the second during the following night. The flights should be scheduled between two and three o’clock in the afternoon and just before sunrise during the hottest month of the year. Ideally, the experiment is able to be conducted under “heatwave conditions” - after a few consecutive hot days and importantly, without cloudiness or precipitation during the experiment and the preceding 24 hours. These trips during summer should be supplemented with additional flights in spring or autumn and winter, in order to pick up changes in foliage cover and seasonal vegetation growth, as well as different radiation impacts due to changing sun angles. Sensors utilized in this study achieve a spatial resolution of better than 1m accuracy, and include a hyper-spectral scanner and a thermal imager to record images across visual (VIS), near (NIR) and short-wave (SWIR) spectral bands and thermal infrared (TIR) with a minimum temperature resolution of 0.1K. Additionally, a laser scanner measures the height of the underlying terrain to a vertical accuracy 0.02m and a full-waveform LiDAR provides detailed 3D-information of the urban form geometry. 3.2. In-situ measurements Stratified sampling based on a comprehensive urban form classification will support a randomized selection of a small number of case studies. Neighbourhood areas within the flight transect will be classified according to urban form features, such as street orientation, dwelling density and urban structure, H/W/L-ratio of urban canyon and vegetation content. In-situ measurements will be performed with mobile sensors mounted on a bicycle trailer along predefined routes within the sampling area. These traverses will be carried out simultaneously to the

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airborne data collection, for a continuous period of 24 hours at one hour intervals in each case study area. The instrumentation mounted at approximately 1m height includes six radiation sensors oriented in different directions to measure long- and short-wave radiation from the sky and emitted or reflected by the urban form, including upward emissions from the ground and those sideways oriented from vertical surfaces, such as building structures or vegetation. Combined with a shielded thermometer, a humidity sensor and a GPS device, the equipment is connected to a laptop and powered by a solar panel.

4. RECOMMENDATIONS AND CONCLUDING REMARKS Despite the considerable amount of research that has been undertaken in the field of urban climatology over recent decades, findings have not been easily accessible to city planners and urban designers, and thus have rarely been employed in the design of neighbourhoods or streets [30]. There is a need for further research to explore the complex interplay between built environment and urban climate at a micro scale, with the aim to quantify the relationship between elevated urban temperatures and different elements of urban form. It is desirable to develop methodologies that enable an effective region wide risk assessment of urban areas to identify precincts and streets that are particularly vulnerable to the effects of urban warming. This ongoing research aims to demonstrate how urban design can play its part in reducing the carbon footprint of our cities and increase the resilience of the urban environment to the impacts of urban warming. This improved understanding can support the development of urban design guidelines for precincts, and to explore possible design interventions for existing suburbs, in order to ensure the continued wellbeing and prosperity of its Australia’s urban residents.

5. ACKNOWLEDGEMENTS The author would like to acknowledge the support of the University of Sydney and CSIRO’s Urban Systems Program in funding this research. I would like to thank Prof. Alan Peters, Faculty of Architecture, Design and Planning, University of Sydney, Dr. Matthew Inman and Guy Barnett, CSIRO Ecosystem Sciences, and Alice Thompson for their ongoing support and advice. Furthermore I would like to thank Nik Midlam, City of Sydney, for facilitating access to thermal imagery and local weather station data.

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6. REFERENCES [1] UN. World Urbanization Prospects. 2009 [cited 2010 14 June 2010]; Available from: http://esa.un.org/unpd/wup/index.htm. [2] MajorCitiesUnit, State of the Australian Cities 2010. 2010, Infrastructure Australia: Canberra. [3] ABS. Regional Population Growth, Australia, 2008-09. 2010 [cited 2010 18 August]; Available from: http://www.abs.gov.au/ausstats/[email protected]/Produ cts/3218.0~200809~Main+Features~Main+Features?OpenDocu ment#PARALINK6. [4] Howard, L., The climate of London deduced from meteorological observations made in the metropolis and at various places around it [microform]. Goldsmiths'-Kress library of economic literature ; no. 28395. 1833, London: Harvey and Darton. [5] Givoni, B., Climate Considerations in Building and Urban Design. 1998, New York: Van Nostrand Reinhold. [6] Akbari, H., Energy Saving Potentials and Air Quality Benefits of Urban Heat Island Mitigation. Solar Energy, 2001. [7] Oke, T.R., City size and the urban heat island. Atmospheric Environment (1967), 1973. 7(8): p. 769-779. [8] Watkins, R., et al., Increased Temperature and Intensification of the Urban Heat Island: Implications for Human Comfort and Urban Design. Built Environment, 2007. 33(1): p. 8596. [9] Fouillet, A., et al. Has the impact of heat waves on mortality changed in France since the European heat wave of summer 2003? A study of the 2006 heat wave. World Climate Report 2008 [cited 2009 18 May]; Available from: http://www.worldclimatereport.com/index.php/20 08/02/14/few-french-fried-in-2006/. [10] Vaneckova, P., et al., Effect of temperature on mortality during the six warmer months in Sydney, Australia, between 1993 and 2004. Environmental Research, 2008. 108(3): p. 361369. [11] Vidal, J., World feeling the heat as 17 countries experience record temperatures, in Guardian. 2010: London. [12] ABCNews. Melbourne morgue full after heatwave deaths. 2009 [cited 2009 10 June]; Available from: http://www.abc.net.au/news/stories/2009/02/06/2 484219.htm. [13] Henry, K. The 2010 Intergenerational Report. 2010; Available from: http://www.treasury.gov.au/igr/igr2010/report/ht ml/02_Chapter_1_Economic_and_demographic. asp. [14] Garnaut, R., Garnaut Climate Change Review. 2007, Commonwealth of Australia: Canberra.

[15] Stern, N., The Stern Review on the Economics of Climate Change. 2006. [16] CSIRO and BOM, State of the Climate. 2010, CSIRO and the Australian Bureau of Meteorology: Canberra. [17] IPCC, Report on Climate Change. 2007, United Nations Environment Programme (UNEP),World Meteorological Organization (WMO). [18] Newman, P.W.G. and J.R. Kenworthy, The land use--transport connection : An overview. Land Use Policy, 1996. 13(1): p. 1-22. [19] City.of.Sydney, Sustainable Sydney 2030. 2008, The Council of the City of Sydney: Sydney. [20] Hall, T., Where have all the gardens gone? An investigation into the disappearance of back yards in the newer Australian suburb. 2007, Urban Research Program: Griffith University, Brisbane, Australia. p. 1-51. [21] Oke, T.R., The Urban Energy Balance. Progress in Physical Geography, 1988b. 12(4): p. 471508. [22] Arnfield, A.J., Two decades of urban climate research: A review of turbulence, exchanges of energy and water, and the urban heat island. International Journal of Climatology, 2003. 23(1): p. 1-26. [23] Bornstein, R.D., Observations of the Urban Heat Island Effect in New York City. Journal of Applied Meteorology, 1968. 7: p. 575-682. [24] Oke, T.R., Boundary Layer Climates. 1987, New York: Methuen & Co. [25] Oke, T.R., Canyon geometry and the nocturnal urban heat island: Comparison of scale model and field observations. International Journal of Climatology, 1981. 1(3): p. 237-254. [26] Taha, H., Urban climates and heat islands: albedo, evapotranspiration, and anthropogenic heat. Energy and Buildings, 1997. 25(2): p. 99103. [27] Akbari, H., Cooling Our Communities. A Guidebook on Tree Planing and Light-colored Surfacing. 2009: Lawrence Berkely National Laboratory. [28] Sailor, D., Simulated urban climate response to modifications in surface albedo and vegetative cover. Journal of Applied Meteorology and Climatology, 1995. 34(7): p. 1694–1704. [29] Oke, T.R., Street design and urban canopy layer climate. Energy and Buildings, 1988a. 11(1-3): p. 103-113. [30] Golany, G.S., Urban design morphology and thermal performance. Atmospheric Environment, 1996. 30(3): p. 455-465. [31] Akbari, H., Shade trees reduce building energy use and CO2 emissions from power plants. Environmental Pollution, 2002. 116(Supplement 1): p. S119-S126.

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[32] Oke, T.R., et al., The Micrometeorology of the Urban Forest [and Discussion]. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 1989. 324(1223): p. 335-349. [33] Brack, C.L. Pollution mitigation and carbon sequestration by an urban forest. 2002: Elsevier Sci Ltd. [34] Lee, S.H., et al., Effect of an urban park on air temperature differences in a central business district area. Landscape and Ecological Engineering, 2009. 5(2): p. 183-191. [35] Yu, C. and W.N. Hien, Thermal benefits of city parks. Energy and Buildings, 2006. 38(2): p. 105-120. [36] Alexandri, E. and P. Jones, Temperature decreases in an urban canyon due to green walls and green roofs in diverse climates. Building and Environment, 2008. 43(4): p. 480493. [37] Sailor, D.J., Simulations of annual degree day impacts of urban vegetative augmentation. Atmospheric Environment, 1998. 32(1): p. 4352. [38] Wen, Y. and Z. Lian, Influence of air conditioners utilization on urban thermal environment. Applied Thermal Engineering, 2008. 29: p. 670-675. [39] Aniello, C., et al., Mapping micro-urban heat islands using LANDSAT TM and a GIS. Computers & Geosciences, 1995. 21(8): p. 965967. [40] Gluch, R., et al., A multi-scale approach to urban thermal analysis. Remote Sensing of Environment, 2006. 104(2): p. 123-132. [41] Stathopoulou, M. and C. Cartalis, Daytime urban heat islands from Landsat ETM+ and Corine land cover data: An application to major cities in Greece. Solar Energy, 2007. 81(3): p. 358-368. [42] Voogt, J.A. and T.R. Oke, Thermal remote sensing of urban climates. Remote Sensing of Environment, 2003. 86(3): p. 370-384. [43] Weng, Q. and D.A. Quattrochi, Thermal remote sensing of urban areas: An introduction to the special issue. Remote Sensing of Environment, 2006. 104(2): p. 119-122. [44] Stone, B. and M.O. Rodgers, Urban form and thermal efficiency - How the design of cities influences the urban heat island effect. Journal of the American Planning Association, 2001. 67(2): p. 186-198.

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Improving areas around railway stations to promote changes in the mode of transportation Yves HANIN, Véronique CLETTE, Amélie DAEMS, Thomas DAWANCE, Martin GRANDJEAN, Véronique ROUSSEAUX 1 1

Conférence permanente du développement territorial, Université Catholique de Louvain, Louvain-la-Neuve and Université Libre de Bruxelles, Brussels, Belgium

ABSTRACT: The renewal of rail transport brings railway station districts back in the spotlight and raises the question about their (re)development. Whereas the strategies to be implemented must be geared chiefly to transport mode shift, they also provide an opportunity to revitalise these areas and to rebuilt the city around a bolstered central core. These strategies vary depending on the type of station. Sixty (60) Walloon stations have been described according to three criteria: passenger flow (departure/arrivals, people going to and from work/school …), land occupation in the district (including available land reserves), and access by the various modes of transport. On this basis, general guidelines for improvement have been established. Keywords: railway station district – passenger flow – land occupation – town planning – transport mode shift

1.

INTRODUCTION

Until recently, both in cities and in rural areas, the immediate surroundings of railway stations were normally not paid attention to when promoting urban development. However, over the recent years, a number of changes in people’s transportation patters seem to underpin development and progress in the railway transportation system. In the late eighties, the railway sector was subject to many innovations and offered the public a modern image and user-friendly mode of transportation. Furthermore, the introduction of high speed trains, undoubtedly contributed to an increased use of the railway over medium distances. During the nineties, the increased use of trains, led to the construction of new stations and railway lines. Today, a number of railway modernization projects are ongoing, especially in connection with the development of the regional express network around Brussels. This renewed focus and investments in the railway sector, are caused by multiple factors. The two most apparent reasons being (i) changes in transport policies driven by international requirements (for instance the Kyoto Protocol) and the excess numbers of users of the road networks (causing traffic congestion), and (ii) an increased cost associated with the use of private vehicles, both with respect to higher fuel prices, and increased costs associated with accessing cities (parking fees, toll fees, etc.). The current policy in Wallonia seems to support establishment of parking areas around the main stations of departure, and a concentration of offices around the main stations of arrivals. To determine how relevant this policy is, and see how it can be incorporated in more comprehensive urban and rural

development plans, a study was accomplished. The study was conducted as part of the “Standing Conference on Territorial Development (CPDT) – cpdt.wallonie.be” in collaboration with the Ministry of Land Management and Urban Planning, the Ministry of Equipment and transport, the Walloon Regional Transport Company, the National Society of Belgian Railways and the Federal Ministry of Finance (Cadastre unit). The research identified changes in people’s travelling patterns and illustrated the characteristics and potential of railway stations in the Walloon region of Belgium. Based on the first assessment, a list of concrete proposals for the development of areas directly surrounding various types of railway stations was established.

2.

DIVERSITY OF AND PLACES

PRACTICES,

2.1. Understanding changes travelling pattern

in

FLOWS people’s

Studies on mobility and travelling patterns clearly indicate an increase in the average distance that people travel on a daily basis. They also point out that the travelling patterns are becoming increasingly complex as places of residence, offices/businesses, education, shopping and recreation are increasingly fragmented over a larger area. With this background, two changes should be evident among commuters: (i) More and more people have a car and the use of personal vehicles increases, and (ii) People are trying to establish chains of movement to connect their residences, workplaces, and social infrastructure including shopping, recreation, and education facilities. However traffic jams and new incentives for public transport encourage the use of different transport modes.

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The predominance of private cars is also supported by spatial transformations in metropolitan areas, causing new travelling patterns other than those traditionally observed between city center and the suburbs. In fact, the city center is no longer necessarily an area where all activities are based, and equally, the suburbs are not only a location for residences and daily services. 2.2. Understanding the flow of railway users in Wallonia In the Wallon region, the railway covers about 9% of all daily trips, whereas private cars represent 80%, the bus 4% and other modes of transport (e.g. walking, cycling, etc.) represent more or less 7%. Thanks to the commercial services of the national railway, the mentioned study was able to use and refer to a significant database showing passengers’ travels in Wallonia. This database allowed us to identify points of origin and destination, as well as type of passengers and their residential locations. By selecting 60 stations, a daily movement of 102.500 commuters was analyzed, representing nearly two thirds of the total market share of railway passengers. The remaining third was composed of occasional trips (one-way tickets) and special tickets (e.g. multiple cards travels). From this database, the analysis could conclude the following: Walloons working in Wallonia are hardly using the railways. Most of the working commuters go to Brussels. The internal movements in Wallonia are mainly related to school, while the departures are made up by mostly workers. However, the smaller the station, the more equal is the number of people departing for school and for work, while the number of people arriving is predominantly composed of workers. The daily travel related to schools is shorter than the daily travel of workers. Consequently departures for reasons of work are less dominant if the station is near a major hub.

3.

BEYOND THE MAIN TRENDS, THE PARTICULARITIES OF WALLOON RAILWAY STATIONS

To address issues related to development of rural and urban areas with regards to the railway stations, it is necessary to develop specific strategies depending on what type of station it is, - whether it is a major destination station, a mixed station with an equal number of departures and arrivals, or one of the many small stations with mainly departures. These specific strategies should take into account the particularities of the stations, their surroundings

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and their accessibility for the people who use the services from the station. To do this, the 60 stations that were studied were classified according to three factors: The flow of subscribers, the development of the land surrounding the station, and the accessibility for users. 3.1. Types of railway station according to the flow of passengers In addition to the four major Walloon stations (Namur St., Liege St., Mons St. and Charleroi St.), other stations can be classified into four groups according to their relative importance, passenger flow (departure or arrival) and type of users (related to work, school or mixed). The first group of stations is characterized by mainly being a point of departure for workers, mainly commuting to Brussels, and by the arrival of schoolchildren typically from neighboring towns. A second group consists of stations mainly used by workers going in the direction of a major hub, along with arrival and departure of students and workers to nearby cities. A third group consists of modest and small stations, mainly characterized by the departure of workers and normally having less than 250 arrivals (students and few workers). The fourth group of stations includes those with very specific features, like stations with a large number of student departures and few arrivals. 3.2. Types of stations according to the land use A second set of classification was developed, based on the land use in the neighborhood of the 60 stations studied. The neighborhood concept refers to the area within a radius of 800 meters surrounding the station. The social and urban aspects are not taken into consideration at this stage in the definition. The 60 stations were classified into five major types, according to the development of the land surrounding the station. A first group of stations consisted of those located in heavily urbanized areas, where unutilized plots represent less than 8% of the surrounding area. Another group includes stations located in less developed/urbanized neighborhoods, where about 60% of the land is devoted to agriculture and forestry. The majority of the surrounding buildings are for residential purposes. The largest group of stations is those located in residential neighborhoods. This group is further divided in two, depending on whether the neighborhood includes large reserves of land or whether it is more densely built. The last two groups are characterized by the presence of industrial parks/areas within the surrounding of the station.

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Figure 1: Types of station according to the flow of passengers and the land use

3.3. Types of stations in terms of accessibility For each of the 60 stations, accessibility was determined by examining how the passengers reached the station, either by car (“park and ride" or "kiss and ride "), public transport, on bike or by foot. A general conclusion emerges from the study, which is that the accessibility of the station is closely correlated with the development and land use in the surrounding area. Urban stations alone stand for 10,600 departures to Brussels, or a third of the total movement to the capital. Nearly 55% of these subscribers are going to their departure station by private car. The presence of a main road within 500 meters from the train station provides a convenient access when using private vehicles. However, thanks to public transportation being available within short distance to the urban railway stations, nearly 20% of the passengers use this in order to reach their departure station. Urban stations have the lowest number of users accessing the station by cycling and walking, compared to all the other types of stations. The rate of car use, related to the access to stations in urban and industrial areas is very similar

to the urban stations, but use of public transportation accounts for only 12%. Of commuters located in a predominantly residential neighborhood, 60% go by car to the station, 35% walking and just 7% use public transportation. For the residential stations with large reserves of undeveloped land in the surrounding area, people access the station in a similar fashion as those using rural stations, mainly by cycling and walking. This can be explained by the proximity of people’s residence to the railway station and the limited public transportation services.

4.

DEVELOPMENT STRATEGIES AROUND STATIONS

The final objective of the study was to propose some strategies to be applied when developing areas around railway stations as a mean to promote a change in transportation patterns. The conclusions reached on the patterns of passengers, the use and development of the land around stations and the accessibility of the different types of stations allowed us to consider different strategies in developing these areas. The different strategies will not be explained in detail in this brief, but some general remarks follows.

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We emphasize that the choices regarding land use and development of the areas around stations, especially with regards to accessibility issues and expansion of structural entities should be included in a charter involving railroad companies and both regional and local operators. This charter should express not only regional and local operators’ willingness to upgrade stations to promote increased use, but also the potential of improving railway linkages and the frequencies of the trains. We also believe that development and improvement of areas around railway stations requires strategic interventions at different scales. At the level of municipalities and cities, the proposed urban development interventions should not compete with the projects specifically planned around the railway station areas. The general structure around the station should be taken into consideration, and influences of new interventions need to be thoroughly assessed. A development plan covering a larger area should provide the guidelines that to be followed in designing the operational plans. Improvements regarding means of access to the railway station will require establishment of road networks and expansion of public transportation within the area surrounding the station. Also, development of surrounding pathways should be enhanced in order to facilitate people cycling and walking. These principles, set out according to the strategies related to the types of railway district should be included in the charter. The improvement should strategically strengthening three functions of the station: The modal centrality, and the destinationand departure functions. The stations are central structures, to varying degrees, making up essential junction points for the population in an area. After losing some of their th symbolic power in the 20 century, they have again become vital meeting points and centers for transportation.This can be further enhanced by improving the qualities of the space surrounding stations and by developing other type of infrastructure making the railway stations more convenient and attractive centers. The station should in other words be considered as a “development hub” – central in both local and regional dynamics. Furthermore, the station has a double role as both a point of destination and departure. Depending on the weight of these two roles, activities and facilities must be provided and adapted. This will naturally depend on the station’s place in the network.

5. CONCLUSIONS The mentioned study attempts to lay out the groundwork for a new policy. Too often the railway is seen as a way of federal transportation and therefore does not take into consideration regional concerns. While there are projects focusing on regional issues, such as the RER (rapid transit system), the modernization of stations and railway lines, the

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urgency of a comprehensive strategy should be addressed. Locally, the station and its surroundings have a negative perception among people. Few people wish to expand this infrastructure, even though it would increase the travelling convenience and opportunities. However, the station and its neighborhood should be valued as important assets of municipal- and urban development. A change to this perspective requires both a strong political will of regional authorities and transport operators to implementation an urban planning strategy addressing the problems linked to these facilities (noise and vibration of trains, arriving and departing flows from the station, insecurity, etc.) It is therefore urgent to put Wallonia on track and to promote mobility of the inhabitants in the region. This collective challenge will directly impact the development of our region and the quality of life for its people.

6. REFERENCES [1] Althabegoity H. (1998), Pour une stratégie du réseau des gares regionals, dans “Revue des chemins de fer” n°4, pp. 69-75 [2] Bahn-Ville (étude franco-allemande) sur http://www.bahn-ville.net/fr [3] Conférence Permanente du développement territorial CPDT (2005), Protocole de Kyoto : aménagement du territoire, mobilité et urbanisme, MRW, DGATLP, Collection Etudes et documents, série CPDT n°6 [4] Dawance T. (2002), Les sites degares face aux enjeux de structuration du territoire en faveur d’un report de mode : synthèse d’expériences étrangères, dans Mutations spatiales et structures territoriales, rapport final de la subvention 2002, CPDT, Thème 1, septembre 2003, vol.2, pp109 et s. [5] Gouvernement Wallon (1999), Schéma de Développement de l’Espace Régional, DGATLP, Namur [6] Halleux J.-M. et Lambotte J.-M. (2002), « Quantification et analyse évolutive de la désurbanisation », in Les coûts de la désurbanisation, Etudes et documents n°1, Namur – Belgium [7] Hubert J.-P. et Toint Ph. (2002), la mobilité quotidienne des belges, Presses universitaires de Namur, 347 pp. [8] Kaufmann V. (2000), Mobilité quotidienne et dynamique urbaines, la question du report modal, Science, Techniques, Société, Lausanne – Switzerland [9] Menerault Ph. (2001), Gares et quartiers de gares : signes et marges, éd INRETS, coll. Actes n°77, 2001, 216 pp. [10] Service du Premier Ministre (2001), Service fédéraux des affaires scientifiques, techniques et culturelles, Enquête nationale sur la mobilité des ménages – réalisation et résultats, Rapport final.

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Creating a sustainable transport system - a study of the comprehensive mobility plan, issues thereof and policies adopted in Pune urban region in India. Jayashree DESHPANDE Director, National Institute of Advanced Studies in Architecture, Pune, India ABSTRACT: In recent years, rapid economic developments and expectations of better job opportunities and superior living conditions are becoming major determinants of the migration which has contributed significantly to the sizeable increase in the population of Indian cities. In an attempt to accommodate the swelling population, cities, faced with an unprecedented pace of construction, are greatly expanding their physical boundaries resulting in a series of overlapping and interconnected effects. Living conditions in core areas of cities as well as the suburbs are far from ideal and are becoming increasingly critical. The failure of the public transport system in providing reliable, economic and rapid conveyance is increasingly forcing large sections of the population to fall back upon privately owned vehicles leading to pollution and traffic snarls. This paper examines the relationship between the growth pattern of Indian cities and issues of urban transportation, with special reference to the city of Pune located in Western Maharashtra in India. It outlines the features of a comprehensive mobility plan for Pune giving priority to pedestrians, non motorized transport and all modes of public transport. The paper analyses the policies to be implemented for the creation of a ‘people oriented’ city and emphasizes on the active participation of all stakeholders including citizens and independent non-government organizations in the process of creating a sustainable transport system. Keywords: comprehensive mobility plan, urban transportation

1. INTRODUCTION The urban expansion which has been taking place the world over since the last few hundred years has been considerably noticeable since the beginning of the last century. India has been no exception to this phenomenon. Rapid economic developments and expectations of better job opportunities together with superior living conditions are becoming major determinants of the migration from the rural into the metropolitan areas. This has contributed significantly to the sizeable increase in the population of Indian cities in recent years. In an attempt to accommodate the swelling population cities are faced with an unprecedented pace of construction. This is causing an expansion of their physical boundaries resulting in a series of overlapping and interconnected effects. As a consequence of inadequate infrastructure and limited financial resources, living conditions in core areas of Indian cities, as well as their suburbs are far from ideal and are becoming increasingly critical.

  2. THE PUNE SCENARIO

The growth pattern of the city of Pune in Maharashtra State of India is influenced considerably by the influx of population caused by the growth of various industry segments. The

issues of transportation within the city and its suburbs are assuming a grave significance. Pune is a city situated approximately 180 kilometres southeast of Mumbai at an elevation of approximately 560 meters above sea level at the confluence of the Mula and Mutha rivers. It is bounded by hills on the western side and the Sinhagad-Katraj hilly area to the south. Pune lies at the confluence of three national highways. National Highway 4 or NH4, a part of the Golden Quadrilateral of highways in India runs between Mumbai in the west and Chennai in the south covering 1,235 km through the states of Maharashtra, Karnataka, Andhra Pradesh and Tamil Nadu. It connects Pune to several major cities such as Satara, Kolhapur and Kagal and villages in Maharashtra as well as Bangalore in Karnataka. National Highway 9 or NH9 with a total length of 841 km passes through the states of Maharashtra, Karnataka and Andhra Pradesh connecting Pune to Machilipatnam in Andhra Pradesh. National Highway 50, or NH50 officially listed as running over 192 km, runs within the state of Maharashtra connecting the cities of Nasik and Pune. The Pune road network has developed around these three main highways and connects Pune city to 1866 villages in 14 'talukas' or territories within 15,642 sq. km. of Pune district. Formerly, fondly called as the Oxford of the East, pensioners’ paradise and city of cyclists,

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Pune has been spectator to the vibrant growth of the industrial, commercial as well as the educational sector. The presence of various Central and State Government establishments is also notable. Industries dealing with automobiles, auto components, forgings and mechanical components are giving Pune a new identity as the ‘Detroit of India’, while food processing and service industries like IT and IT enabled services have also made a noteworthy presence in the city. A large proportion of the city’s commercial establishments flourish on wholesale and retail trade and commerce. The city serves as the regional wholesale market for food grains and other commodities. In the education sector, the city has six universities which include above 600 affiliated colleges with an estimated student population exceeding five hundred and fifty thousand. In recent years, Pune has attracted over 8000 students from more than 62 countries. Pune has thus emerged as the centre and hub for a wide range of diversified activities and over the past 30 years, urbanized areas have increased several times. Once famous for its greenery, open spaces, clean air and the beautiful lush green hills surrounding it, today it holds the dubious distinction of being one of India’s most congested and polluted cities. The ease of connectivity to native places coupled with opportunities of better jobs and higher education in Pune have been luring youth from neighbouring and far places to settle in this city. In an attempt to accommodate the swelling population, Pune is faced with a rapid and unparalleled pace of construction. Although the most important function of cities today should be to provide the best possible environment and quality of life for all those living and working there, living conditions in cities are far from ideal.The process of rapid urbanization is also greatly expanding the physical boundaries of large cities creating suburbs or ‘annexes’? to existing suburbs. Real estate markets project the myth of a false paradise created within these suburbs and massive numbers of middle income families lured by promises of superior living possibilities within affordable prices move to these areas which are located far away from workplaces.

non polluting modes of transport or for the quality of life. The public bus transport system is in a state of utter neglect. Inadequate number of buses as compared to the population, poor quality of vehicles, erratic frequencies, not so convenient routes and high cost of tickets add to the miseries of the commuters. An organised city taxi service is almost non-existent and the three wheeled auto rickshaw service is the only public mode of transport available, albeit expensive, for travel to the desired destination. The failure of any of the existing public transport systems in providing reliable, economic and rapid conveyance is instrumental in increasingly forcing large sections of the population to fall back upon privately owned two and four wheeled vehicles. In such a scenario, travel to and from the work places is generating a large volume of traffic on Pune roads. This has been leading to pollution and traffic snarls. In addition, transportation problems in Pune city become chaotic throughout the rainy season and also during yearly religious events like the ten day Ganesh Festival and Palkhi Procession. The unrelenting growth of traffic has become a major deterrent to the enhanced growth of the city and perhaps the greatest environmental threat. Around 2500 State Government owned interstate bus transport vehicles in addition to the privately owned luxury bus services connect the city of Pune, round the clock, to the five adjoining states through five inter-city bus terminuses. There are several pickup points for the interstate buses which are located within the city thus adding to the traffic woes. .

3. ISSUES OF URBAN TRANSPORTATION As part of the globalization process, in Pune, the orientation of Government polices has been towards building expressways, promoting private vehicular transport and reducing excise duty on motorised vehicles. With improved production and the increasing affordability of cars there has been a corresponding rise in the construction of motorways within the city and the development of suburbs. In order to provide for the increasing number of vehicles entering the inner city, new roads are being built, existing roads enlarged by cutting trees, and open spaces being converted into parking lots. The old urban fabric is getting destroyed as large scale urban renewal is initiated with little or no regard either for pedestrians and

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Chaotic traffic on one of the main arterial roads in Pune. There is a similar environmental deterioration, rising pollution and increasing traffic paralysis in many cities of India. It is therefore becoming obligatory to work out a sustainable transport policy which will respect the relationship between transport, energy and pollution and their effects on

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the quality of the local environment. In order to effect meaningful changes, there is a need to carefully re-examine the planning theories that are being adopted in our cities. For all practical purposes, a sustainable transport system would be one which serves the common vision of an urban region’s economic and social development while focusing on: • easing access and mobility for people to reach work, services, resources, and each other. • providing access for all groups in the society, including children, the aged and the differently able, in a manner that is within the environmental carrying capacity of the region • being affordable to both the providers and users of transport systems. • providing for smooth movement of goods within cities. Increasing prosperity, growth in population, changing demands and new economic requirements make it necessary for the authorities to review their land policies continuously. There is a need to create the will, the financial resources and the management capabilities to improve the urban infrastructure. Policy makers will have to take drastic and even unpopular actions in order to adequately meet the rapidly changing demands of the urban population in the coming decade.

4. THE TRANSPORT POLICY: ORGANISED APPROACH  

AN

The National Urban Transport Policy (NUTP), formulated by the Ministry of Urban Development in 2006 aims to transform the current urban transport system into a safe, convenient and efficient transportation system across all urban areas in India. As per the mandate of the ministry, cities are required to prepare a “Comprehensive Mobility Plan (CMP) that focuses on the mobility of people rather than vehicles giving priority to pedestrians, Non-Motorized Transport (NMT) and all modes of public transport. The CMP for Pune city has been drafted following the broad vision of “Moving people safely and economically by emphasizing public transport and non-motorized transport.” Some of the broad approaches of the CMP for Pune city in order to achieve the above vision include: • Identification of a number of trunk mobility corridors along which high capacity public transport systems such as Bus Rapid Transit (BRT)/Monorail/LRT/Metro, etc would be considered. • Enhancing the capacity and quality of the public transport so that people are motivated to use it instead of relying on personal two and four wheeled motor vehicles. • Providing alternative routes in the form of ring roads to enable the core city areas and main city roads to be bypassed by long distance commuters and goods carrying truck traffic. • Identifying feeder systems that connect different areas in the city to the most

convenient node in one or more of the mobility corridors. • Providing a network of dedicated cycle tracks, footpaths and pedestrian crossings with emphasis on the safety of users. • Pedestrianising important zones within the core city area and linking them with strategic parking places to encourage people to walk in such areas. • Judiciously providing flyovers in a few heavily congested junctions/intersections to reduce idling traffic. • Special attention towards road safety. • Introduction of physical and fiscal measures that would discourage the use of personal motor vehicles. • Reforming and strengthening the institutional arrangements for managing and regulating the transport system in the city. Several initiatives have been taken by The Pune Municipal Corporation (PMC) to improve the traffic and transport situation in Pune. A 6 lane, 170 km long ring road is planned to connect the peripherals with the city and serve as a bypass for heavy vehicles. This is also expected to ensure that heavy vehicles and trucks do not ply on the inner circuits, thereby reducing traffic congestion. At the same time it would lessen the pollution within the city and provide relief to buffer zones like schools and hospitals, which are at present being subjected to sound pollution due to heavy vehicular traffic. The Pune Bus Rapid Transit (BRT) system, the first of its kind in India was implemented with the noble intention of fighting traffic congestion. However, it has been severely criticized and leaves tremendous scope for improvement on account of inadequate planning, lack of enforcement of dedicated lanes for buses, and haste in rolling out the project. .

A file photograph depicting dedicated lanes for buses under the Pune BRT System. The PMC has attempted to promote cycling by making cycle tracks along the roads such that they are segregated from vehicular traffic. On roads having width of 80 ft or more, separate cycle tracks are given by setting aside strips in each direction adjacent to the foot path and segregated

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from the fast lane by dividers. On roads with the width less than 80 ft and having heavy cycle flows in both the directions, priority to cycle traffic is given by proving cycle tracks on both the sides and introducing one way schemes for motorized vehicles on other existing arterial roads. However such schemes have served to increase the speed of vehicular traffic on the arterial roads while compromising on the safety of pedestrians and cyclists while at the same time increasing commuting distances and inconveniencing the bus travellers. .

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Encourage industries and institutions to provide for employee housing on campus or at least make arrangement for the mass movement of their employees. • Design and relocate interstate bus terminuses to the peripheral areas of the city, to be connected to core city area by an independent public minibus system. There may be nothing new in the above measures. In a situation where mobility has now become a major issue for the society, it is certainly not easy to find the correct solutions in a system of economic, social, societal and environmental equations. However, it is for this reason that, to create ‘people oriented’ cities, policies will have to be implemented with the active participation of all stakeholders including citizens and independent non-government organisations. The decision making processes will have to be more open, more transparent and more inclusive. Decisions need to be taken with the involvement of local experts in order to develop a range of mechanisms to receive support for implementation and meaningful feedback on performance. It is the sense of belonging and pride instilled in the involved stakeholders which will go a long way towards contributing to the successful implementation of remedial measures.

A representative image of a public not educated in traffic rules using the motorway for cycling despite the provision of an independent cycle track.

  5. CONCLUSIONS

In order to see the plans achieve the desired results, creating awareness and educating the large local as well as the rapidly growing, undisciplined rural, migrant population about the background, intentions and expected outcomes of such schemes is absolutely necessary. Schemes must be designed and implemented with the vision for the next fifty years and not as patchwork remedial measures of short term duration. Implementation of these approaches would necessitate drastic steps to: • Improve the image, capacity, quality and cost of the bus public transport system. • Constrain the use of personal motor vehicles by reducing parking areas, restricting entry, levying taxes and parking fee, higher fuel cost etc. • Intelligently integrate the existing system of three wheeled auto rickshaws to economically connect to the larger mobility corridors by introducing the concepts of share-an-auto and point-to-point movement plans. • Give lower priority to road widening and flyovers, but wherever necessary do it in a manner to make cycling and walking safer.

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                                                                                                                                                                                            

                                                                                     

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                                                                                                           

PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES) 

301

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                                              



                 

                              

                              

 

                   



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                  

302

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                                                               

                             

                                                                                                                                     

PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

 

        

        

        

        

        

        

        



                                                                                                                    

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                                      

                                                          

                   

                                                                                                                                                                                                                                         

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PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

303

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

        

                                                                                                                                              

       

 

                                                                      

                                              

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 

PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                                             

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 

                                                                 

                                                                          

                                                                                                                                 

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 PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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    



                                                                                                            

                                                                                                                                                                                       

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                                                                                                                                                                                                                 

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PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 

                                                                                                                           

                                                                                                                                               

                                                         

                                                                                                                                                                                                      

                   

308

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PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 

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        

               

                                                          

     

  

 

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           

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   

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     

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            

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    

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       

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                                                                                                                                               

  

      

 



 

      

 

   

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PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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309

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 

             



    



   









    









  

 

 









                    













        



           



   





















   











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                                                                                                                                                                                               

   

    

  

  

 

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310

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

PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 

                                          

                        

   

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 

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 

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                                                                                                                                                                     

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                                                          

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PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 

                                                                                                                                                                                                                                                                                                                           

         

                                                                                                                                                                                                                        

                                    

                                     

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ARCHITE ECTURE AND SUSTAINABLE S DEVELOPMEN NT, Proceedings s of PLEA 2011, Louvain-la-Ne euve, Belgium (J July 2011) ISBNth xxx-x-xxxxx-xxxx-x - ISB BN (USB stick) xxx-x-xxxx-xxxx x x-x @ Presses universitaires u de e Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The e Code e for Su ustaina able Ho omes as a a via able driiver to owards s a zero o carbo on futu ure in U UK 1 He eba ELSHA ARKAWY, Pe eter RUTHERFORD, Ro obin WILSO ON 1

Departmentt of Architecturre and Built En nvironment, University U of No ottingham, No ottingham, UK K

ABST TRACT: The urge for lowe er carbon emisssions from buildings b has seen s the deve elopment of policies p to cater forr energy consserving metho ods in new and a existing buildings, b inno ovative metho ods of conserrving and generatin ng energy and d numerous ca ampaigns to help h raise awa areness of carb bon footprints. However in a growing world po opulation and d an increasin ng number off people now w living in urb ban areas, acchieving high levels of sustainab bility fronts many m challenge es. Among the ese include overcoming the e barriers thatt society pose es, that of behaviou ural and social patterns whiich drive energ gy consumptio on and resourrce use. It is arrgued that suc ch factors form the basis of choicces, habits an nd values of in ndividuals and d which impact on an individ dual’s decision n to act in favour of or against environmentall e lly sustainable e / energy effi ficient behavio ours. Howeverr, in order to meet the e red duction target, the governm ment’s approac ch in confronting householld carbon emissions is carbon emissions predomin nantly policy-b based. This diiscussion refle ects on how th his specific are rea of energy p policy is being g enacted through policy p and reg gulation, particcularly through h the CSH. Th he outcome is an examinatiion of the likely y impacts of the po olicy on the en nergy consum mption behavio our, together with w investigatiing how delive ering on the policy may (not) lead d to the assum med target. Keyword ds: energy con nsumption, cod de for sustaina able homes, behaviour, b poliicies

1. INTR RODUCTION N: Energy Consumption n in th he UK Dome estic Sector ‘Domesticc sector enerrgy consumptiion is defined d as energy ussed in dwellin ngs, excluding g petrol and otther fuel use for family carrs (which are classified un nder transport)). It also impllies energy ussed in residen ntial establishm ments such as a hotels.’ (U Utley & Shorro ock, 2008) Energ gy use in the domestic d secttor accounts fo or a large p proportion o of total n national ene ergy consumption. In the 1970s it accou unted for 24-2 27% of UK en nergy consum mption but sin nce 1980 it has risen to 28-31% 2 of UK K energy consumption (Utle ey & Shorrock, 2008). In 2005 the UK K’s total carbon e we ere 556 MtC CO2 (Mega ton dioxide emissions Carbon Dioxide). Em missions from m the dome estic s represe ent around 27 7 per cent of this housing sector figure (D DCLG, 2007). The average e UK househ hold creates almost a five an nd a half tonn nes of CO2 evvery year to heat and powe er their home (EST, 2009). To gets domesticc emissions have meet govvernment targ to fall to 17 MtC p.a. by b 2050, if the e domestic sector r in line with overall carbon c emissions were to reduce targets (M McManus, Gatterell and Coa ates 2010). Statistics show that t much of the carbon emissionss from homes is due to heating (over 80% % of heating systems s in UK U are fuelled d by gas) (G GCH 2010), both of space e and water with househ hold electricityy consumption accounting for fewer emissionss (see Fig 1)). The Deparrtment of Ene ergy and Climate Change (DECC) ( claim ms in its quartterly hat carbon emissions e from the dome estic review th sector de ecreased by 5% % between 20 008 and 2009 but also poin nts out that th his fall was due d to a raise e in overall te emperatures in n the subsequ uent year (DEC CC, 2010). However, H even if there iss evidence of o a reduction in household d carbon emisssions, this does

nott necessarily indicate thatt people are changing the eir way of life e in ord der to lower their hou usehold ene ergy con nsumptions. Consequently, of pattterns con nsumption and a use er behaviour may m hav ve the effectt of neg gating some of the e ben nefit exp pected frrom red ducing the carrbon intensityy of the e UK’s energy Fig 1: Energy used d for heating sou urces in the fu uture. purp poses in hous seholds in According to Gardner G w Carbon and (1996), 2008 (UK Low d Stern nsition Plan, 200 09) Tran pollicy instrument is reg garded as one e potential ap pproach for drriving proenv vironmental behaviour b (Gardner and Ste ern 1996). The paper foccuses on p policy instrum ment and scusses the Code C for Susta ainable Homes that has dis bee en adopted in n UK since 20 008. It discusses a few beh havioural and d policy impliccations that might m (not) hellp achieve the e predicted ou utcomes of applying this pollicy to the new wly built domesstic sector in UK. U

2. LOW CA ARBON OMESTIC SE ECTOR DO

INITIATIVES

IN

UK

In the UK K, new de evelopment delivering eco onomies of sccale is required d to bring dow wn costs of env vironmental te echnologies th hat could app ply to new and d existing hom mes. The Depa artment of Communities and d Local Government (DCLG G) proposes to t achieve a zero z carbon goal g in three steps: movin ng first, in 2010 to a 25 2 percent improvementt in the

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

energy/carbon performance set in Building Regulations; then second, in 2013, to a 44 percent improvement; then, finally in 2016, to zero carbon. Zero carbon means that, over a year, the net carbon emissions from all energy use in the home would be zero (see Table 1) (DCLG, 2007). Policy instruments have been developing for 40 years, with standards for limiting energy loss through buildings first introduced in the 1965 Building Regulations, which now falls under Approved Document L1 of the current building regulations, ‘Conservation of Fuel and Power’ which takes account of limiting heat gains and losses, as well as of energy efficient building services and controls (McManus, Gaterell and Coates 2010). Also, the Standard Assessment Procedure (SAP) rating provides a useful measure of potential energy performance that feeds directly into Part L (DEFRA 2005). In 2007, the government published the Code for Sustainable Homes (CSH)- built upon the existing policy Ecohomes- as a pathway to achieving zero carbon homes in England and sets ambitious targets for the house building industry. A mandatory rating against the Code builds on Energy Performance Certificates (EPCs), which have become compulsory since October 2008 whenever a building has been built, sold or rented out. Government has proposed that all new homes will be built to the ‘zero-carbon’ standard from 2016, with interim energy requirements based on those contained within the Code (DCLG 2008). Notably, there are a number of other closely related government initiatives that have been introduced. This includes: the Stamp Duty Land Tax, exemption for zero carbon homes, the criteria for meeting the energy components of the Code for Sustainable Homes, the details of the amendments to be made to the energy efficiency and carbon requirements of the Building Regulations in 2010 and 2013, the requirements for eco-towns to be zero carbon and several other initiatives. Ongoing consultations take into account, where relevant, the lessons learnt to date in the development of this policy (CLG, 2008). Moreover, in an attempt to create widespread uptake of renewable energy technologies, the UK government has brought about schemes such as Feed-in-Tariffs (FITs) and a proposed Renewable Heat Incentive (RHI) as well as a Pay As You Save (PAYS) scheme for ‘green’ financing. The following section discusses CSH as a viable solution in the UK to minimise energy use in newly built homes. 2.1 The Code for Sustainable Homes (CSH) “Energy policy for homes is being taken forward through a number of routes and the Code for Sustainable Homes is a major driver for achieving low and zero carbon homes.” (ZeroCarbonHub, 2009) The CSH has been developed with the Building Research Establishment (BRE) and is an effectively bespoke version of Ecohomes for the domestic sector in England. To support the Code, CLG has worked with BRE to put in place an assessment and certification system. The Code is part of a wider

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package of measures which is aimed at reducing UK carbon emissions from buildings and adapting to climate change (CLG 2007). It takes a whole house approach and measures the sustainability of a dwelling against nine different categories: energy/carbon; water; waste; materials; surface water run-off; and health and well being, which have mandatory performance standards; and pollution; ecology; and management. Central to the CSH are the energy efficiency and CO2 emissions of new homes, which are embedded in a mandatory section of the CSH in which minimum standards must be met in order to become accredited (linked to SAP and Part L) (DCLG, 2007). Depending on the number of points gathered, a star rating is then awarded (one star being the lowest achievable level and six stars being a zero carbon home, see Table 1). Table 1: Shows regulatory steps to zero carbon and corresponding Code levels. (CLG, 2009) Code Level

1 2 3 4 5 6

Current energy standard (Percentage improvement over 2006 Part L) 10% 18% 25% 44% 100% regulated emissions Zero carbon onsite -100% onsite plus appliances

When change to regulations takes place

2010 2013

2016

2009 Code consultation proposals (Percentage improvement over 2006 Part L) 25% 25% 25% 44% 70% onsite+30% allowable solutions “Zero Carbon Home”- 70% onsite+allowable solutions to reach zero carbon

In a study by Osmani and O’Reilly, they affirm that the introduction of the CSH as legislation, along with the implementation of Energy Performance Certificates -in line with the European Energy Performance of Buildings Directive- is highly successful in terms of reductions in CO2 emissions and cost effectiveness, to the point that these measures could be major drivers for zero carbon housing (Osmani & O’Reilly, 2009). However, some studies proved that what appeared best to the tenants, delivering them the greatest perceived benefit, may well not equate to optimum usage of the systems from an efficiency point of view, and may not in turn deliver ‘design level’ carbon savings (Pett and Guertler 2004), (EnergyActionScotland, 2002). This is discussed in the following section, which highlights a few implications to the successful delivery of the CSH.

3. DISCUSSION: Implications to the Code delivery “Much behaviour in our everyday lives require the use of energy. Taken together, these energy-related behaviours steadily lead to adverse environmental effects. Households contribute to these energyrelated problems and constitute an important target group for energy conservation. It is therefore important to examine how to effectively encourage

PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

PLEA2011 - 27th International conference e on Passive an nd Low Energy Architecture, A Lo ouvain-la-Neuve e, Belgium, 13-1 15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

onservation and a to exam mine householld energy co which facctors underlie e household energy use and conservation. Energ gy conserva ation can be accomplisshed by ch hanging existting behavioural patterns, thereby reduccing househollds’ impact on the ment”. (Abraham mse, 2007) environm The question q is: ho ow does the government plan p to inform m people on a mass scale with detailed, comprehe ensible inform mation of the e changes they t would ne eed to make in order to establish a zero z carbon fu uture? The Warm W Homes, Greener Hom mes strategy set s out in Marcch 2010 highliights that in orrder to suppo ort the conssumer in ho ousehold ene ergy managem ment, nationa al advice prrovision will be provided, informing in ndividuals of how to reduce energy byy making changes to behavviour, eligibilityy of subsidiess and where to find more e tailored advvice (HMGove ernment 2010)). As stated byy Parag & Darby, meeting demanding carbon re eduction targ gets nment to takke actions that t requires the Govern ‘encapsulate interest’ in emissions reductions r (Pa arag & Darby, 2009). ever, when measuring m the effectivenesss of Howe interventions in energ gy savings, itt is importantt to examine the extent to which the inttervention ressults in both en nergy savingss and behaviou ural changes that t supports this saving (A Abrahamse, 2007). 2 In orde er to w the CS SH can effectivvely deliver on n its assess whether aims, thiss will require examining a number of key areas rela ating to the so olutions likely to be employyed, and the environment e in n which these e solutions will be operating g. The users’ energy e consum mption behaviour and policcy implication ns will make e the difference between promising po olicy, and policy which in fact delivers on its aimss for energyy efficiency and sustainab bility. 3.1 Users s’ energy con nsumption be ehaviour A keyy determinant of energy co onsumption within households is users’ behaviour. b Over the long te erm, g fastest from appliancces, energy demand has grown ergy for heating remaining g largely stable, with ene although recent chang ges are mucch smaller (G GCH 2010). It has been notted that policyy changes to the way hom mes are built or retrofitted will only reduce carbon emissions e to a certain exte ent; whereas the bigger ch hallenge of addressing beha aviour patterns of consumption needs to be targeted iff new homes are to be ad ddressed as zero-carbon. Two of many implicatio ons of the efffect of userrs’ behaviour on energy consumption are a discussed d in the follow wing abits, and the rebound effecct. section; liifestyle and ha 3.1.1 Life estyle and ha abits Energ gy consumptio on is often inconspicuouss to individualls as it becom mes part of an ordinary lifesstyle such as the use off household appliances and household heating patterns. He eiskanen (20 009) hat consumptiion behaviourr is not based d on implies th individuallistic choices rather r shared conventions that t evolve historically, creating common n understandings of decen ncy and ap ppropriate be ehaviour. These conventio ons are a resu ult of a vast co ommercial systtem of techno ologies and media m that provide p collecctive “comfort, cleanliness and convenience”’ signifyying

the e enormity of what w creates cconsumption behaviour. b No onetheless, it is ultimately th he choices of individuals tha at become a key k factor in th he process off changing con nsumption beh haviour (Heiskkanen et al, 2009). This is clear c in a stud dy of social ho ousing tenants s in the UK (Pe ett & Guertle er, 2004) wh here energy efficiency me easures had been b installed d, only 23% of o tenants surrveyed were e using their heating systems ‘effficiently’, as designed. Th he majority were w using the em to suit their lifestyle, but not utiilising the sys stems at optim mum efficiencyy. In another study of a Co ode level 5 home, it ha as been imp plied how imp portant contrrol systems are to be properly reg gulated and designed d apprropriately for users and tha at this should be considered at the early design sta age (Hormaza abal et al., 2009). This has also rec cently been recognised by the Sustainable De evelopment Commission C in n the develo opment of pollicies for behaviour b ch hange towarrds more env vironmentally sustainable behaviour (SDC C 2006). Personal hab bits are also o one of the main barriers to sustainable s en nergy consum mption. Habits come into exiistence when n ‘behaviourss are freque ently and con nsistently rep peated’ (Becchtel and Churchman C 200 02) and beco ome a major factor in pred dicting the outtcomes of a behaviour b change as they are a unique to individuals. Jackson J highlights that habits occur ainst rational choice and de escribes them m as being aga parrt of low cogn nitive processses that requiire little in the e way of thinkking or even unconscious decisions. As this is the ca ase, they ofte en tend to inte erfere with a to makke decisions in his/her an individual’s ability ow wn best interesst (Jackson, 2 2005). Even though t an ind dividual may intend to red duce househo old energy em missions for exxample, habitt or routine may m cause the em to do otherwise. o In order for successful s beh haviour chang ge, old habits need to be broken and new w ones established (Stern, 2000). Even if policies are e in place to induce envirronmentally sustainable beh haviour, the choice of short term rew ward that orig ginates from existing habitts may override paying the e consequence es for the actio on. 3.1 1.2 ‘Rebound Effect’ The ‘rebound effect’ may have important beh havioural imp plications that might impactt the CSH dellivery. It is an a umbrella term for a variety of me echanisms th hat reduce the potentia al energy sav vings from im mproved ene ergy efficienc cy. In the con ntext of houssing, home-ow wners may be b able to affo ord to heat th heir home to a higher stan ndard, and ma ay also use the e cost savingss from energy-efficiency imp provements to o purchase oth her goods and d Energyy efficient home

 

• Energy efficient homes E

Lower running costs  saving money • Higher levels of comfort • Purchase mo ore electrical  appliances, ...etc

Redu ucing energy  conssumption • Increase in energy  consumption • 'Rebound effect'

Fig g 2. Illustration of the optimal scenario and th he ‘rebound effe ect’ scenario in n energy efficie ent homes (ad dapted from (So orrell, 2009))

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

services that require energy in the eir provision e.g. flights, co onsumer goods, etc (Sorrrell, 2009).Sorrell has implied that on th he micro levell, the question n is whether improvementss in the techn nical efficiencyy of u can be expected to reduce ene ergy energy use consumption by the amount pred dicted by sim mple ons. Simple economic e the eory engineering calculatio suggests that it will not; since energy-efficie ency ments reduce the marginal cost of ene ergy improvem services such as travvel, the consu umption of those e to increase. This T services may be expected d consumption n of energy services s mayy be increased expected to offset so ome or all of o the prediccted nsumption. reduction in energy con This rebound r will have h a negattive impact when examining g the overalll energy con nsumption of the dwelling. McManus et al. a suggest tha at this issue must m c of tech hnologies likelyy to be undersstood in the context be installed to meet th he Code requiirements, with h an edgement thatt the major influencing factor acknowle will be th he pattern of usage of the ese systems and that tenants will need to be well infformed about the appropria ate methods of using energy efficcient technolog gies provided in their Code homes. It has also bee en suggested that some of the nega ative effects – the rebound effect e as an examplee mustt be considere ed as part of the t policy stra ategy such as the CSH sta andards (McM Manus, Gate erell, & Coates, 2010). ns 3.2 Policy implication on making with w Policyy formulation and decisio respect to environm mental issuess tend to be complicatted. Typicallyy, there are many kindss of factors to consider -physical, psychologiical, economicc, ethical, and political - as well w as the ofttenconflicting g interests off different gro oups. In fact, the complexitty of environ nmental decission problemss is such thatt they may ap ppear to defy rational analyysis, and that effort to esttablish enviro onmental policcies er controversyy on many isssues (Nickersson, encounte 2003), (M McManus, Ga aterell, & Coates, 2010). The T 2007 White Paper on Energy E has se et out a response to the Energy Review w Report, invvolving increased internatio onal cooperatio on as well ass action at ho ome (DTI, 200 07). One of th he key elemen nts of its strattegy has been n stated as: “E Encourage mo ore energy savving through better b informattion, incentive es and regulattion. By removving barriers to t the take up p of cost-effecctive energy efficiency e measures, all of o us, busine ess, individualls and the pu ublic sector, ccan take stepss to reduce em missions and our energy de ependence” (D DTI, 2007). Although it seem ms as a comp patible solution n to o the grou ups’ financiallyy support reduction of household emissions, it does little e in the wayy of changing behaviour to encourage persisttent sustainab ble energy consumption ass individuals may m not conttinue to beh have in an environmenttally responsib ble manner. It is imperative i tha at the CSH aims a to prom mote higher en nvironmental standards s in housing h ahead d of implemen ntation of regulatory standards; as all new n homes would be requirred to have a mandatory Code dicating wheth her they had been assessed rating ind and, the performance of the home against a the Code

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(DC CLG, 2007). Itt has also bee en stated by CLG C that to furtther support the aim of zero carbon n homes; pla anning policy will w be develop ped by the Go overnment to set a framew work for development to de eliver zero es (DCLG, 200 07). Besides, proposals carrbon outcome for a Planning Policy P Stateme ent on Climatte Change ve been pub blished to asssist using the e national hav pla anning structure in supportiing the delive ery of zero carrbon homes (C CLG, 2008). The higher levels l of the CSH (Codes 5 and 6) hav ve the poten ntial to signifficantly reduc ce energy con nsumption an nd carbon fo ootprints built to these sta andards (McM Manus, Gatere ell and Coates 2010). Ho owever, govern nment exhorta ations to reduce energy con nsumption will w go unh heeded if they t are inc congruous with the social a and physical context of eve eryday life. Ba arriers, such as financial costs, c past beh haviour, socia al values and physical infra astructure, are e considered some s of the m most intractable barriers to changing ene ergy behaviours. Another barrier to ach hieving the presumed outcomes of these inc centives is the e lack of pub blicity and bro oadcasting the em to the pu ublic in comp prehensive an nd tailored app proaches that could possiibly target mo ost socioeco onomic secto ors of peop ple. The Sustainable De evelopment Commission C (S SDC) has im mplied that con nsumers need d clear and cconsistent sign nals about pollicy directionss and prioritie es in order to t change beh haviour. It hass been suggessted that policies should o take up stro ongly engage e and encoura age people to pro o-environmenttal actions alo ong with usin ng energy effiicient homes and techno ologies most efficiently (se ee fig. 3).

Fig g 3: The diamond model su ummarises the key policy rec commendations for reducing ccarbon emission ns from the exis sting housing sttock. (SDC, 200 06)

Assessing the effectiveness e of policy inte erventions req quires a clear understanding of consumer mo otivations acro oss all incom me groups so o that the mo ost appropriate approachess are develop ped (SDC, 200 06).

4. CONCLUSIO ON Policy signals have a ma ajor influence on social norrms, ethical codes and cultural expectations (Ja ackson, 2005 5). Howeverr, the comp plexity of

PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

environmental decision problems is such that they may appear to defy rational analysis, and that effort to establish environmental policies encounter controversy on many issues (Nickerson, 2003), (McManus, Gaterell, & Coates, 2010). It is assured that public policy-making in general and environmental policy-making in particular, is a process concerned with values. This concerns the identification of desirable goals and the selection of tools for moving development towards these goals (Lundmark, Matti and Michanek 2010). Notably, sustainability policy in the UK has progressively shifted from a centralised ‘top-down’ towards a distributed ‘bottom-up’ approach in implementing sustainable development policy (DEFRA, 2005). Thus, the initial conceptions of public involvement in sustainability have become centred around consultation with the placement of the behaviour change agenda at the centre of the most recent Sustainable Development Strategy, thus reinforcing the role of the individual in the sustainable development framework (Barr, 2008). However, current thinking suggests that it would be infeasible for government to change individual consumer behaviours. Yet, not all research supports this presumption as government inevitably plays a vital role in shaping the cultural context within which individual choice is negotiated. This is made obvious through its influence on technology, market design, institutional structures, the media, and the moral framing of social goods (Jackson & Michaelis, 2003). Yet, current legislation does little to tackle underlying values and address the issue of habits -which as discussed previously- exist as a result of routine behaviour and recurring events (Verplanken and Wood, 2006). Concerning options for driving behavioural change; Abrahamse et al assert that this can be done either at the macro-level; through policy instruments, economic benefits etc., or at the microlevel; involving education and information tailored and disseminated to individual households. Both approaches are required, and both will entail benefits and drawbacks, as mentioned in their research. Abrahamse demonstrated that providing a household with information tends to result in higher knowledge levels, but not necessarily in behavioural changes or energy savings (Abrahamse 2007). Meanwhile, there are ways in which the user can be incentivised to change their behaviour in order to gain maximum benefit from any available technology in energy efficient homes. Gardner and Stern have suggested three types of incentives that have been used effectively to promote energy conservation in homes: energy price changes, financial rewards for desired behaviour, and methods that simplify the task of conserving energy and thus make conservation more convenient (Gardner and Stern 1996). In fact it has been implied that the reasons given for changing one’s behaviour are motivated both by lower energy costs, a reduced impact on the environment, and sometimes even better health (Stern, Berry, & Hirst, 1985).

 

“Existing policies and technologies would bring down the emissions in 2020 to about 500 MtCO2, achieving about a 15 per cent reduction from 1990’s level, which falls well short of the target reduction implied by the legislated carbon budget relevant for 2020” (Anandarajah, Ekins, & Strachan, 2011). Although the higher levels of the Code have the potential to reduce domestic energy use significantly, it still remains unclear whether delivering this aim in reality would achieve the zero carbon homes target. It can be said then, that if habits are developed over time, a zero carbon culture may be achievable in the future, but effectively changing behaviour to more energy efficient behaviour may not be possible as soon as interventions set in, such as CSH. Clearly then, the Government has mainly opted to gain compliance without making positive changes in underlying values to establish a new culture of low carbon lifestyles. Thus it is not guaranteed that ‘zerocarbon’ housing as currently defined within the Code will actually deliver the UK zero carbon target, if new approaches for policy design and interventions are not taken on board.

5. ACKNOWLEDGEMENTS I would like to thank Dr. Peter Rutherford for his guidance, time and support. I would also like to thank Saeema Hawaldar and Dr Robin Wilson for their helpful contributions.

5. REFERENCES [1]

Abrahamse,  Wokje.  “Energy  Conservation  through  behavioural change: Examining the effectiveness of  a  tailor‐made  approach.”  PhD  thesis.  Netherlands:  Rij ksuniversiteit Groningen, 6 December 2007. 

[2]

Abrahamse,  Wokje,  Linda  Steg,  Charles  Vlek,  and  Talib  Rothengatter.  “The  effect  of  tailored  information,  goal  setting,  and  tailored  feedback  on  household  energy  use,  energy‐related  behaviors,  and  behavioral  antecedents.”  Journal  of  Environmental Psychology, 27 (4), 2007: 265‐276. 

[3]

Anandarajah, Gabriel, Paul Ekins, and Neil Strachan.  “Pathways  to  a  low  carbon  economy.”  In  Energy  2050, Making the Transition to a Secure Low Carbon  Energy  System,  by  Jim  Skea,  Paul  Ekins  and  Mark  Winskel, 105‐145. London: Earthscan, 2011. 

[4]

CLG.  Definition  of  Zero  Carbon  Homes  and  Non  Domestic  Buildings:  Consultation.  London:  Crown  copyright, 2008. 

[5]

CLG.  Sustainable  New  Homes‐  The  Road  to  Zero  Carbon.  London:  Communities  and  Local  Government, 2009. 

[6]

CLG. The future of the Code for Sustainable Homes:  Making a rating mandatory. London: DCLG, 2007. 

[7]

DCLG.  “Cost  analysis  of  the  Code  for  Sustainable  Homes: Final report.” London, 2008. 

[8]

DCLG. The Callcutt review of housebuilding delivery.  London: HMSO, 2007. 

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

[9]

DEFRA.  The  Government's  Standard  Assessment  Procedure  for  Energy  Rating  of  Dwellings.  London:  Crown Copyrights, 2005. 

[10] DEFRA,  Department  of  the  Environment,  Food  and  Rural  Affairs.  Securing  the  Future:  UK  Government  sustainable  development  strategy.  London:  The  Stationary Office, 2005.  [11] DTI, Department of Trade and Industry. Meeting the  Energy  Challenge:  A  White  Paper  on  Energy  May  2007. Norwich: The Secretary Office, 2007.  [12] EnergyActionScotland.  Revisiting  Easthall:  10  Years  On. Glasgow: EnergyActionScotland, 2002.  [13] Gardner,  Gerald  T.,  and  Paul  C.  Stern.  Environmental  Problems  and  Human  Behaviour.  Massachusetts: Allyn and Bacon, 1996. 

[24] Sorrell,  Steve.  “Jevon's  Paradox  revisited:  The  evidence  for  backfire  from  improved  energy  efficiency.” Energy Policy (Elsevier) 37 (2009): 1456‐ 1469.  [25] Stern,  Paul  C.,  Linda  G.  Berry,  and  Eric  Hirst.  “Residential  Conservation  Incentives.”  Energy  Policy, 1985: 133‐142.  [26] Utley, J I, and LD Shorrock. Domestic energy fact file  2008. BRE, London: Crown copyrights, 2008.  [27] ZeroCarbonHub. Defining Zero Carbon Homes: Have  your say. London: Zero Carbon Hub, 2009. 

 

[14] Hormazabal, Nina, Mark Gillott, Guillermo Guzman,  and  G.  Revell.  “The  Effect  of  Technological  User  Control  Systems  on  Occupants  of  Sustainable  Energy  Homes.”  26th  Conference  on  Passive  and  Low Energy Architecture,. Quebec: PLEA, 2009.  [15] Jackson,  Tim.  Motivating  Sustainable  Consumption:  a  review  of  evidence  on  consumer  behaviour  and  behavioural  change.  ESRC  Technologies  Programme,  Centre  for  Environmental  Strategy,  Surrey: University of Surrey, 2005.  [16] Jackson,  Tim,  and  Laurie  Michaelis.  Policies  for  Sustainable  Consumption.  London:  Sustainable  Development Commission, 2003.  [17] Linden,  Anna‐Lisa,  Annika  Carlsson‐Kanyamab,  and  Bjorn  Eriksson.  “Efficient  and  inefficient  aspects  of  residential  energy  behaviour:What  are  the  policy  instruments  for  change?”  Energy  Policy,  2006:  (34)1918‐1927.  [18] Lundmark,  Carina,  Simon  Matti,  and  Gabriel  Michanek.  “The  Swedish  environmental  nrm:  Balancing environmental obligations and the pursuit  of individual lifestyles.” In Environmental Policy and  Household  Behaviour:  Sustainability  and  Everyday  Life, by Patrik Soderholm, 13‐42. London: Earthscan,  2010.  [19] McManus,  A.,  M.R.  Gaterell,  and  L.E.  Coates.  “The  potential  of  the  Code  for  Sustainable  Homes  to  deliver genuine ‘sustainableenergy’ in the UK social  housing sector.” Energy Policy, 2010.  [20] Nickerson,  Raymond  S.  Psychology  and  Environmental  Change.  Mahwah:  Lawrence  Erlbaum Associates, Inc., 2003.  [21] Osmani,  M.,  and  A.  O’Reilly.  “Feasibility  of  zero  carbon homes in England by 2016: A house builder's  perspective.”  Building  and  Environment  44  (2009):  1917‐1924.  [22] Pett,  Jacky,  and  Pedro  Guertler.  User  behaviour  in  energy  efficient  homes.  Lonon:  Association  for  the  Conservation of Energy, 2004.  [23] SDC,  Sustainable  Development  Commission.  Stock  Take:  Delivering  improvements  in  existing  houses.  London:  Sustainable  Development  Commission,  2006. 

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

        

                                                                                                                                                                                                  

                                                                                                                                                                                                                       

                                       

            

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PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

319

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

                                                                                                                                                                                                                                                                                                                             

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                                                                                                                             

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 

                                                

PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

                                                   

                                                and             

  

 

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                                    

                  

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 

                                                                                                                                   

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 

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PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

321

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

                                                                                            

                                                                                      

 

                                                                                                   

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 

                          

PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

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PROGRAMMING (MULTI FUNCTION AND MULTI GENERATION) / MOBILITY (IN AND BETWEEN CITIES)

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MATERIAL (ENVIRONMENTAL AND HEALTH ASPECTS) / WASTE MANAGEMENT

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Straw Bale Construction; a Solution for Low Cost Energy Efficient Rural Housing in the Earthquake Affected Regions of Central Southern Chile? Christopher J. W HITMAN1, Daniela FERNÁNDEZ HOLLOWAY1 1

Laboratorio de Energía e Iluminación, Faculty of Architecture, Art and Design, Universidad Andrés Bello, Santiago de Chile, Chile

ABSTRACT: Following the earthquake of February 2010 in central southern Chile almost 80,000 families have been re-housed in “mediaguas,” temporary timber emergency shelters 18m2, as they await the rebuilding of their damaged properties. Even before the earthquake, a survey conducted in 2007 by the Chilean charity, Un Techo para Chile recorded 28,578 families living in shanty towns. In addition a study conducted between the winter of 2007 and summer of 2008, showed that a large percentage of the Chilean population live during the winter in poor hygrothermal conditions with over 80% suffering problems with condensation and moulds. An affordable, renewable resource, with excellent insulation properties, currently burned as a waste material adding to carbon emission, straw bales could offer an affordable solution to providing energy efficient housing especially when considering rural locations. This paper presents the research of the authors regarding the hygrothermal performance of straw bales in central Chile, with results from physical test chambers, and the application of this construction typology to designs for permanent housing solutions. Keywords: Energy, Comfort, Low Cost Housing, Straw Bale, Natural Disaster Relief

1. INTRODUCTION At 3.34am on the 27th of February 2010 an earthquake of magnitude 8.8 on the Richter scale hit central southern Chile. Affecting an area of around 600km in length and felt by over 80% of the Chilean population, the earthquake left 521 people dead, 56 missing [4], 103,543 dwellings destroyed, 105,039 severely damaged [5] and many more requiring varying degrees of repair.

2. CHILEAN HOUSING SITUATION Pre-earthquake housing deficit Even before the earthquake Chile’s housing deficit was not insignificant. According to the 2002 census 15% of the urban population were recorded as living in self built shelters or homeless, [6] a figure that rises to 37.64% of the total Chilean population [7] when those sharing dwellings are included. Of this figure the rural homeless population represents 19%. According to the National Survey of Shantytowns undertaken by the charity ‘Un Techo para Chile,’ in 2007 there existed in Chile 533 shantytowns (campamentos) housing 28,578 families. Of these 73% were located in the earthquake-affected zone th (5-9 and Metropolitan Regions) [2]. Prior to the earthquake ‘Un Techo para Chile,’ along with other charities and government agencies had the objective of eradicating these slums by 2010 with the provision of definitive housing that met with the Chilean building regulations. Often during this process, as a stepping-stone families would be moved into volunteer built “mediaguas” temporary timber shelters 18m2 costing approximately US$915 [8] In addition to the quantitative housing deficit Chile also suffers from one that is qualitative. A report on

annual household fuel bills of Chilean families indicates that in 2006 all but the richest two fifths of the Chilean population could be classed as energy poor [9,10]. In addition a study by the Chilean national government program for energy efficiency, Programa País Eficiencia Energética PPEE and the German technical Cooperation GTZ showed that a large percentage of the Chilean population live during the winter in poor hygrothermal conditions, with over 80% suffering problems with condensation and moulds [3]. This problem is further exasperated by high usage of freestanding, naked flame, liquid gas or paraffin heaters, or inefficient wood burning stoves. Although historically adobe was the traditional construction technique in rural central Chile, this has now been replaced by timber and masonry. A survey of the principal building materials of a typical village near Santiago in 2009 recorded 65% of all buildings were of timber framed, timber clad construction; 25% masonry; 7% adobe, principally in the historic centre of the village; and the remaining 3% of timber frame with sheet metal cladding [11]. The majority of the dwellings are without any insulation, apart from those built following the introduction of Chilean Thermal Building Regulations in 2000 for roofs and 2007 for walls. Assuming an average timber cladding thickness of 15mm and an internal finish of 12mm plasterboard this would provide a u-value of 2.362W/m²K, whereas those complying with the Thermal Building Regulations would have a maximum u-value of 1.9W/m²K which although being an improvement is insufficient given the climatic conditions with cold winters and average monthly dry bulb temperatures as shown in Table 1.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 1. Maximum (max.), Minimum (min.) and daily average (avg.) dry bulb temperatures ªC for Santiago de Chile. [12]

Month

Max.

Min.

Avg.

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

33.0 32.0 33.0 30.0 27.0 22.3 20.0 28.2 25.3 29.0 31.0 33.2

10.0 9.0 4.0 -0.3 -0.3 -1.4 -2.2 -6.0 -0.5 2.0 4.2 8.0

21.0 20.3 17.9 14.1 11.0 9.1 7.6 9.3 11.4 14.4 17.1 20.2

Post-earthquake housing deficit Directly following the earthquake the Chilean government, in conjunction with the military and various Chilean and international charities, organised the building of approximately 80,000 [1] “mediaguas”. Of these 4,754 were located in emergency encampments the rest being built on the property of those affected adjacent to their damaged homes. The walls of these timber framed, timber clad, oneroomed temporary structures consist of 5mm thick timber siding with no insulation or internal finishes, providing a u-value of 4.797W/m²K, and considerable infiltrations. In addition to the 80,000 families housed in mediaguas, many other have taken shelter in the homes of relatives or friends, whilst others continue to inhabit their damaged dwellings. A more complete picture of the increase in housing deficit postearthquake can be gained from the number of applications for government subsidies for reconstruction. These applications required the presentation of an official certificate, issued by the local government, proving damage or loss of a principal dwelling as a direct consequence of the earthquake. At the closing date for applications, the th 27 August 2010 a total of 286,678 applications had been received [1]. Government Reconstruction Proposals th

On the 29 March 2010 the Chilean government announced a spending plan of US$2,500 million dedicated to reconstruction [1]. The plan is organised in three main action plans, these being; (i) Rebuilding, repair and replacement of individual single family dwellings; (ii) Repair and replacement of social housing blocks and neighbourhood masterplans; and (iii) Municipal masterplans. Figure 1 illustrates the area affected by the earthquake and the distribution of these mid to large-scale projects, with 21 projects for social housing blocks, 107 neighbourhood masterplans and 100 municipal masterplans [5].

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Figure 1: Plan of Government plans for reconstruction at city or town scale (Masterplan) at neighbourhood scale and social housing estates in the 5th-9th Regions [5]

At the scale of the single family dwelling, in an effort to standardise the process and regulate quality, the government has introduced a system of certified housing solutions from which applicants can choose their new-build dwelling. Costing 380UF (approximately US$16,950) these houses have an 2 average floor area of 45m of various construction systems that must comply with Chilean building regulations. To date 41 designs have been certified, the construction solutions of which are as defined in table 2, and a further 115 are under evaluation [1].

MATERIAL (ENVIRONMENTAL AND HEALTH ASPECTS) / WASTE MANAGEMENT

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

19

3. COULD STRAW SOLUTION?

7

1

Concrete block work

Brickwork

Render

Vinyl siding

Structural and insulation solution Timber with ESP or Mineral wool infill 15 ESP Insulated sandwich OSB panel 4 Uninsulated Brickwork Cold formed steel with mineral wool Reinforced concrete with external ESP

Fibre cement

Timber siding or OSB

Cladding

Table 2. Materiality of the 41 government approved standard house types presently available for those applying for reconstruction grants. [1]

1

24 4

1 3

4

5

3

6 2

10

4

BALES

3

2 4

1

OFFER

41

A

Turning waste into housing During the agricultural productive year 2008-2009 Chile planted 281,000 hectares of wheat, 101,000 of oats, 18,500 of barley and 24,000 of rice. [13] This equates to 0.02 hectares per capita of cereal crops. In comparison, the same year in the UK approximately double the amount 0.05 hectares per capita of cereals were planted. [14] Currently in Chile the straw from these cereal crops is viewed as a waste product and is burnt in the fields further adding to carbon emissions and poor air quality. Concerns over the already saturated air pollution in the capital Santiago, lead last year to the prohibition of agricultural fires during the winter months between st st the 1 of May and the 31 August in the VI Region, the region to the windward side of Santiago. However in 2009 alone 360 prosecutions were brought for infringement of this law. If the straw was viewed as a resource instead of a waste product the straw from all these crops could be used for straw bale construction, thereby reducing green house gas emissions at source and potentially, emissions arising from the heating of rural dwellings. In addition, the majority of cereal production is concentrated in the central zone of Chile, the zone affected by the earthquake and that where 73% of the families previously living in shanty towns are located. If divided between those families previously homeless and those currently rehoused in mediaguas, the area of straw producing cereal crops per family would equate to 4.2 hectares. Assuming a yield of 2690kg of straw per hectare [15] and an average bale weight of 14.5kg [11] this would equate to 781 bales per family, more than sufficient to build a simple single-family dwelling. The use of straw or grasses, in construction

dates back thousands of years; however the first recorded use of straw bales in construction began in the Sand Hills region of Nebraska in the late 19th century. Faced by a shortage of other suitable building materials the settlers of the area turned to the product of the newly invented mechanical baler. These early constructions used the bales in a load bearing fashion with no additional structural members [11]. Although the most straightforward form of straw bale construction, load bearing or Nebraska-style bale structures present some restrictions and difficulties. These include limitations in opening sizes and maintaining walls and corners plumb. In addition there exist concerns over seismic stability despite Californian tests that have proved good resistance to seismic loading by straw bales encased in steel mesh and cement render [16]. For these reasons some degree of timber structure would appear to be an advantage. Thermal properties of straw bales With the combination of the air trapped within the hollow fibres and the overall width of the bale, straw bales provide a high level of thermal insulation. However, being a natural product these values vary considerably depending on compaction, straw type and moisture content. International test results compiled by the authors [11] show coefficients of thermal conductivity (lambda) between 0.034 and 0.15W/mK, and U-values between 0.103, and 2 0.334W/m K. These values show a large variation, one that would be perhaps worrying to someone aiming for a zero energy house, however even the worst of these results would provide 5 times the thermal insulation required by law in central Chile. Test results from physical test chambers In order to test the thermal performance of straw bale construction under central Chilean climatic conditions, three physical test chambers were constructed at the university’s campus Casona de Las Condes in the suburb of Las Condes, Santiago de Chile. These test chambers, each with an equal internal volume, consisted of a timber construction replicating that of a mediagua; a similar timber construction insulated with sufficient expanded polystyrene to comply with the local building regulations (1.9W/m²K), replicating the most common construction solution of the 41 government certified house types; and a third in straw bale construction with a timber frame and 30mm earth render made from recycled adobes. Using Logtag data loggers the internal dry-bulb temperature and relative humidity has been measured hourly since May 2010. It should be noted that during this period the straw bale test chamber had yet to receive its final whitewash finish and as such had a darker surface finish that increases solar thermal radiation absorption. In addition the three test chambers were simulated using TAS software and recorded external temperatures. An averaged coefficient of thermal conductivity of 0.8 W/mK was used for the straw bale. The results of the simulation, figure 3, can be seen in comparison with the actually recorded dry-

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

bulb temperatures that were recorded on the coldest th day recorded to-date the 16 July 2010, figure 4.

Figure 2: Simulation of dry-bulb temperatures with TAS software 16th July 2010, coldest day recorded to-date.

Figure 5: Heating (+) and cooling (-) degree hours calculated from dry-bulb temperature readings in physical test chambers. During winter months May-October 2010

Bureaucratic barriers

Figure 3: Actual dry-bulb temperatures recorded in physical test chambers 16th July 2010, coldest day recorded to-date.

Whilst the real straw bale construction does not provide dry-bulb temperatures as stable as those simulated it still performs better than the other two constructions. The dry-bulb temperatures recorded between May and October 2010 demonstrate that as a result of the superior U-values the heating degree hours, are considerably lower for the straw bale test chamber than those for the timber constructions, figure 5. Measurements of relative humidity show that the straw bale construction maintains an internal RH between 25-60% for 82% of the time, in comparison to only 61% of the time for the timber construction and 71% for the insulated timber construction. It is interesting to note that the construction cost for the straw bale physical test chamber was fractionally less than that of the uninsulated timber test chamber, at a cost of US$140 per usable m² as opposed to US$142 [11]. This would suggest that straw bale emergency shelters could financially compete with mediaguas.

The availability of straw bales as a resource and the empirical data gathered so far by the authors would suggest that this construction type could provide both temporary shelters and replacement low cost rural dwellings that provide a greater degree of hygrothermal comfort and improved energy efficiency. However the Chilean building regulations state that any permanent residential reconstruction receiving state funding must be constructed of a “traditional construction system” or if using a “nontraditional construction system” it must be fully certified by the Technical Department (DITEC) of the Ministry of Housing and Urbanism [17]. To receive this certification the construction system must undergo testing for fire, thermal and acoustic resistance, at a government approved laboratory according to national standards. Despite the existence of international test results that prove an earth rendered straw bale wall can provide a fire resistance of between F60 [18] and F90 [19], a u-value of between 0.103, and 2 0.334W/m K [11] and excellent acoustic separation, national certified test results currently do not exist. Typically the cost for testing at the two government approved laboratories, IDIEM of the Universidad de Chile and DICTUC of the Universidad Católica, has a cost of around US$1,780 a cost not covered by government funds for reconstruction. Currently the authors are bidding for further internal funding from the Univerisdad Andrés Bello to undertake fire resistance testing at one of these laboratories.

4. APPLIED CASE STUDIES The following case studies present the intentions of local architects to use straw bales in both private and state funded reconstruction projects. Case Study 1, Jorge Broughton Arquitectos

Figure 4: Physical test chambers constructed at Casona de las Condes, Universidad Andrés Bello, Santiago de Chile.

330

The Chilean architect and building contractor Jorge Broughton is experienced in building with straw bale. With more than 20 straw bale designand-build projects completed in the last 12 years and a regular organiser of straw bale building workshops in Santiago and the Metropolitan area, Jorge is well aware of the benefits inherent in this type of construction; benefits that he believes could offer a viable solution to the rebuilding of rural communities

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following the earthquake. Following previous contact with the Technical Department (DITEC) of the Ministry of Housing and Urbanism whilst working on the proposals for a social housing project in Lampa, Chile, Broughton was aware of the requirements for test certificates but hoped that owing to the urgency to provide comfortable shelter following the earthquake that these requirements might be relaxed. Following the government’s call for prefabricated 2 housing designs, Broughton designed a 60m straw 2 bale house, with a possible additional 17m in a future first floor extension. The design envisaged the recycling of the timber from the temporary mediagua as internal partitions. The straw bales were to be rendered with a primary coat of earth render to be made from recycling adobes from collapsed houses, finished with a cement and earth top coat. Unfortunately due to the lack of test certificates for the straw bales the design was not accepted for consideration by the Ministry of Housing and Urbanism.

many of the affected communities. With this in mind they developed the designs for a wall prototype that could be reconstructed in place of collapsed adobe walls, with a 500mm concrete block plinth to protect the bales from ground water and large overhanging eaves or external passageways also typical feature in traditional Chilean rural architecture. Armed with this design and the idea of building a number of prototypes that locals could copy, Owar Arquitectos approached the local councils of Lolol in the VI Region and Molina, further south in the VII Region. Due to concerns over the “un-traditional” nature of straw bale construction and inflated construction budgets from local contractors Lolol declined to pursue the project. However the meetings with Molina were greeted with an enthusiastic response and it is hoped that once the council has resolved immediate emergency issues arising in the aftermath of the earthquake, the proposals can be incorporated in the reconstruction of heritage properties that are not covered by the same Building Regulations as new build housing.

Figures 6&7: Sketch and ground floor plan of straw bale single-family dwelling proposed by architect Jorge Broughton

In a parallel project Jorge Broughton has applied for funding from the government’s Corporation for Production Development (CORFO) as part of their call for bids for “Innovation in Reconstruction”. If successful the project will include the necessary laboratory testing to allow for the certification of straw bales construction by DITEC and a series of training workshops in rural communities in the earthquake affected regions. The aim of these workshops would be to train both self-builders and local contractors to repair traditional adobe architecture with straw bales in addition to the construction of new build rural dwellings. The results of the bid should be announced soon. Case Study 2, Owar Arquitectos At the time of the earthquake the office of young Chilean architects Owar Arquitectos were working in conjunction with the North American architect Evan Sellmyer Pruitt, completing the construction of a large single-family house in Coya, VI Region, Chile. The house has a timber frame in-filled with straw bales and is finished with an earth render. Except for minor cracking in the recently completed earth render around a few window openings the house withstood the earthquake undamaged. Based on this experience they too believed that straw bale could offer a solution to the reconstruction in rural Chile. In particular they were drawn to the similarity in the spatial qualities of straw bale constructions and traditional Chilean adobe architecture, qualities that they identified as important in the cultural identity of

Figure 8: Construction sequence of straw bale replacement for adobe boundary wall, Owar Arquitectos

In a parallel project for a private country estate in Almahue, San Vincente de Tagua Tagua, Owar proposed the rebuilding of the estate boundary walls in straw bale on concrete block foundations, bound by nylon ties and topped with a clay tile coping (Fig. 8). The client was enthusiastic and initial material costs came in below budget. However on the receipt of tender returns from local builders it became clear that large additional costs were being added due to the “unknown” nature of the construction technique. Faced with a much lower tender return for a “traditional” fired brick option the client abandoned the straw bales. A related project on the same estate, to rebuild an historic adobe barn with straw bale, fell through when it was discovered that the client’s insurance company did not insure the existing adobe constructions and refused to pay out.

5. CONCLUSION Straw bale construction could turn agricultural waste into affordable, efficient, comfortable rural dwellings; whose thick walls and overhanging eaves reflect the traditional architecture of central southern Chile. Currently due to inexistence of national certified testing of straw bales, inexperience and lack of knowledge of the construction technique it would

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appear that straw bale construction will at present not play a major role in the reconstruction. However if the correct certification were to be obtained, whether through the project CORFO of Jorge Broughton, through a maintained research program by the Laboratory of Energy of the Universidad Andrés Bello or by some other means, then there will be other opportunities. Past experience has shown that reconstruction is not something immediately achieved. Five years after the last major earthquake in Chile, that of Tarapacá 2005, 10% of the rebuilding remains to be completed [20]. A recently announced relaxation of regulations for reconstruction in heritage areas could also open a possibility for the use of straw bales. In addition, if prepared in advance, the design for a temporary straw bale shelter could offer a selfbuild, low cost refuge for future disasters. This could be so designed as to provide an initial refuge that would form the nucleus of a home that could grow in time.

7 8

9 10

11

6. ACKNOWLEDGEMENTS Internal funding “Jorge Millas” project DI-05-09JM of the of the Universidad Andrés Bello has made the research presented possible. Thanks to Jorge Broughton www.arquitecturaenfardos.cl and Owar Arquitectos www.owar.cl for their help and permission to publish their projects.

7. REFERENCES 1

2

3

4

5

6

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Ministerio de Vivienda y Urbanismo (MINVU), 2010, Avances y metas Plan Chile Unido Reconstruye Mejor, 27/09/2010, - MINVUSantiago de Chile. Available at: [Accessed 12 October 2010] Centro de Investigación Social (CIS) - 2007 Catastro Nacional de Campamentos 2007,- Un Techo para Chile - Santiago de Chile. Available.at: [Accessed 28 October 2010] Proyecto Fomento de la Eficiencia Energética (CNE/GTZ) 2008 - Determinación de línea base “anual” para la evaluacion de la inversion en eficiencia energetica en el sector residencial invierno 2007 – verano 2008, - Santiago, Chile. Subsecretaría del Interior de Chile, - 15 May 2010- Fallecidos confirmados – Ministerio de Interior, Santiago de Chile. Available.at: [Accessed 21 October 2010] MINVU Comisión de Estudios Habitacionales y Urbanos (CEHU) 2009 - Déficit UrbanoHabitacional: una mirada integral a la calidad de vida y el habitat residencial en Chile. MINVU- Santiago de Chile.

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13

14

15

16

17

18

19

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MINVU, División Técnica (DITEC) – 2006 – Atlas de la evolución del deficit habitacional en Chile 1992-2002. MINVU, Santiago de Chile Un Techo para Chile, 2009- Información Plan “Construye en Familia”, Un Techo para ChileSantiago de Chile. Available at: [Accessed 28 October 2010] Healy J.D. - 2004 Housing, fuel poverty, and health: A Pan-European Analysis, Ashgate Publishing, Ltd., England Márquez, M. Miranda, R. – 2007 - Una estimación de los impactos en los presupuestos familiares derivados del sostenido aumento en los precios de la energía, Universidad Austral, Valdivia, Chile Whitman C.J. and Fernández D. – 2010- The viability of improving energy efficiency and hygro-thermal comfort of rural social housing in central Chile using straw bale construction. – nd 2 International Conference on Sustainable Construction Materials and Technologies –2830 June 2010 – Ancona, Italy Energy Plus - International Weather for Energy Calculations (IWEC) data for Santiago de Chile [Accessed 5 November 2010] Oficina de Estudios y Politicas Agrarias, - 2009 Estadísticas de superficie sembrada de cultivos anuales, - Santiago de Chile. Available at: [Accessed 14 January 2010] Department of the Environment Food and Rural Affairs. – 2009- Cereals And Oilseed Rape Production Estimates: 2008 Harvest, United Kingdom-Final Results, London Lee, C. and Grove, J.,- 2005 - Straw Yields from Six Small Grain Varieties 2003-4 and 2004-5 growing seasons - University of Kentucky. Available at: [Accessed 8 November 2010] King, B., - 2003 – Load bearing straw bale construction: a summary of worldwide testing and experience - Ecological Building Network (EBNet), California, USA MINVU, DITEC – 2010- Participación de las Empresas en el Proceso de Reconstrucción Vivienda Prefabricada o Industrializada – MINVU, Santiago de Chile Intertek Testing Services NA, Inc. – 2006- 1Hour Fire Testing of a Non-Loadbearing Srawbale Wall, according to ASTM 119-05a Texas, USA Theis, B.,- 2003 - Straw Bale fire Safety, A review of testing and experience to date Ecological Building Network (EBNet), California, USA th Estrella de Iquique, Thursday 25 March 2010, Isasi pide visita presidencial , Iquique.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

An environmental assessment of insulation materials and techniques for exterior period timber-frame walls Hans VALKHOFF Laboratoire de Recherche en Architecture (LRA) de l’Ecole Nationale Supérieure d’Architecture de Toulouse.

ABSTRACT: The French government has instigated an ambitious renovation programme aimed at the thermal insulation of existing housing stock to combat climate change and cut CO2 emissions. This will have a considerable effect on the renovation of period timber-frame houses, a rich architectural heritage in France. This study assesses the environmental impact of thermal insulation of exterior timber-frame walls in vernacular timber-frame buildings with brick or daub infill. The 20 wall types studied are based on the outcome of interviews with builders and building experts. A French building assessment tool, Cocon, is used to calculate embodied energy (EE), embodied carbon (EC) and thermal performance for each wall type. ‘Conventional’ wall types with interior insulation - often mineral wool and plasterboard - generally have the worst overall scores. The highest scores are for wall types with exterior insulation, which make better use of thermal mass. Wall types with interior insulation of plant fibre and binder (e.g. earth/straw) also show good results. Although there is a general lack of technical information on environmental building materials, there is growing evidence that natural and breathable materials are better for the environment, the historic building and the occupant. Keywords: energy, carbon, renovation, life cycle analysis.

1. INTRODUCTION This study focuses on the thermal insulation of period timber-frame houses in the SW of France, a region rich in these historic buildings, the walls of which are traditionally filled with daub or fired brick. The French refurbishment programme, Plan Bâtiment, will have a considerable impact on the renovation of period timber-frame buildings [1]. To combat climate change the French government wants to cut the greenhouse gas (GHG) emissions of the housing sector by almost 40% by 2020 [1]. More than 20 million dwellings will have to be renovated and insulated by 2050 [1]. In the case of housing stock from before 1948, which represents 10 million dwellings in France, this drive for sustainable development may well go against the principles of good conservation [2]. The problem with current thermal regulations is that they are not adapted to historic buildings [3].The building physics of old houses built with traditional materials are very different from those built after 1948, and are often not as well understood [2]. From mistakes made in the past we know how much damage inappropriate renovation and dry lining can do to period timber-frame buildings. Clearly we are only at the beginning of (re)learning about natural and traditional materials and techniques, and their contribution to the energy efficiency of historic buildings [4]. The study aims to answer the question how to renovate historic timber-frame buildings up to modern insulation standards, while preserving the environment and the vernacular qualities of the

building, and reducing the embodied energy (EE) and embodied carbon (EC) of the rehabilitation project. The aim of the assessment is not to compare case studies of entire buildings, but to present a more generally applicable model that helps to define the most appropriate environmental insulation techniques for period timber-frame walls. The focus of the study is on building materials and embodied energy and not on ‘operational’ energy consumption. Today most of the energy use in buildings is due to heating and only 10% of is associated with the embodied energy in materials [5,6,7]. However, as we move towards highly insulated buildings, EE and EC of building materials will become a major part of a building’s energy use and GHG emissions [6].

2. METHODS 2.1. Twenty wall types The study assesses the environmental impact of several insulation techniques and materials presently used in the renovation of timber-frame buildings. A selection of 20 exterior wall types divided into 4 categories was made based on literature review and interviews with builders and building experts (Table 1). For the general build-up of each of the 20 wall types, see Table 3, p.4.

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Table 1 Four categories of wall types in the survey

Wall types I. Conventional wall types with interior insulation :

Number M1 - M5

II. Ecological wall types with interior insulation :

M6 – M10

III. Ecological wall types with plant fibre and binder :

M11 – M15

IV. Wall types with exterior insulation :

M16 - M20

using ‘conventional’ insulation techniques and materials, generally dry lining with mineral wool and plasterboard or clay blocks.

using ‘ecological’ insulation techniques and materials.

using ‘ecological’ insulation techniques and materials, based on solid walls with infill of plant fibre and mineral binder (clay or lime).

The scores for the environmental impact parameters are based on official data from life cycle analysis (LCA), and the scores for the building physics parameters are based on values from French or 2 international thermal regulations . Cocon can be directly linked to the French database INIES which contains Environmental Product Declarations (EPDs) and industry data for 3 building products based on LCA [10] . For product data that are not included in INIES, Cocon uses its own database developed at the LRA, which contains data from the Swiss Oekobilanzdaten or from extrapolations based on other sources [11]. There is a possibility in Cocon to choose ‘with’ or ‘without’ renewable energy (RNE). The reason for including RNE in this assessment is that most data are based on EPDs in INIES [10] which include RNE, despite the fact that this is controversial because these include feedstock energy and cause a bias against renewable materials [12].

using both conventional and ecological insulation techniques

2.3 Thermal performance of a functional unit 2

The functional unit in LCA is usually 1 m of building element for a certain life time (e.g. 50 years). To be able to compare the environmental impact of the 20 wall sections it is better to compare functional units with a similar thermal resistance. In this study an 2 average R-value of approximately 2.7 m K/W was chosen, based on the insulation standard RT-2007, which corresponds with 8 cm of glasswool [9]. To achieve a similar R-value for other insulation materials sometimes required adding an extra centimetre. Most builders interviewed do not apply a vapour control layer (VCL) but leave a cavity of 4cm or 5cm which should be fully ventilated to allow humidity to escape, though often is not. Therefore in the assessment of the conventional wall types (M1-M6) VCLs are not included. Instead a non-ventilated air gap of 4 cm (λ = 0.23 W/m.C) is added to be true to existing renovation practice in SW France. Obviously this hardly influences the outcome in the assessment which does not take vapour transport into account.

The terms ‘conventional’ and ‘ecological’ are indicative and not based on strict definitions. ‘Conventional’ refers to current industrial building techniques which are also common in renovation. ‘Ecological’ applies to the use of materials and techniques that generally have a low impact on the environment. This does not mean that conventional materials and techniques always have a much higher environmental impact. They can even have a low embodied energy (EE), e.g. glasswool, while providing good thermal insulation, though there may be negative impacts such as pollution, toxicity, resource depletion and health risks. On the other hand, so-called ‘ecological’ materials can have a high EE (and EC) and therefore do not perform well in the assessment. 2.2 Life cycle analysis For each wall type the environmental impact of the thermal insulation was assessed using the Excel1 based tool Cocon [8] . Cocon gives each wall an overall score based on the calculation of six parameters: embodied energy, embodied carbon, resource depletion, thermal resistance, decrement delay and thermal inertia (Table 2).

The timbers are not accounted for in the assessment and therefore considered as ‘accessories’, and are not included in the calculations for thermal performance. In most cases the original timbers are kept or reused, which means they are considered ‘existing’ and therefore not included in the impact assessment either. When bricks or daub are reused or left in place as infill one considers them ‘existing’ as well. Again this means they are not included in the impact assessment, though they are included in the thermal calculations because they are not considered accessory. Other accessories, e.g. metal or wood frames for boards and infill are excluded

Table 2 Scores and values for six parameters, wall type M1 (brick, glasswool, plasterboard) Summary Table M 1

Em bodied Energy

Em bodied Carbon

Overall Score

kWh /m²

Score

kg eq CO2/m²

Score

kea

Score

8.5

177.5

8.2

39.7

7.4

0.0281

10.3

Carbon tax

Therm al resistance

Decrem ent delay

Resource Depletion

Therm al Inertia

€ / m²

(m²K/ W)

Score

h

Score

(kJ/ m²K)

Score

0.67 €

2.65

13.6

5.7

9.5

24

1.9

2

The scores are a simple linear interpolation on a somewhat arbitrary scale with an upper and lower limit, taking the real values from the LCA or thermal regulations (RT-2007 and ISO13786). 3 FDES Fiche de Déclaration Environnementale et Sanitaire, based on NF P01-010.

1 COCON - Comparaison de solutions Constructives de Confort et d’emissions de CO2 - is in the process of being approved by the CSTB.

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from the thermal calculations, though they are included in the impact assessment because they are considered ‘new’. Building physics parameters, e.g. air tightness, thermal bridging and vapour control, require simulation software and are therefore not included in the assessment. Qualitative aspects that are hard to quantify, e.g. health issues related to building materials, and above all architectural interest and vernacular qualities, were not included in the assessment. However, the study clarifies whether certain insulation techniques and materials are considered ‘appropriate’ for exterior period timberframe walls.

Looking at Table 3 (p.4) the hempcrete wall (M11) does not get a satisfactory score in the assessment 2 due to its high EE (152 kWh/m ), even though it is 2 virtually carbon neutral (EC = -3.5 kgCO2eq/m ). Changing the lime binder for clay would considerably lower its environmental impact, though hemp and clay is still at an experimental stage and needs more research. With more accurate data for the two lime renders (3 cm each) that take re-carbonation into account, the hempcrete wall would perform better, 2 especially for EE (92 kWh/m ) and EC (-30 2 kgCO2eq/m ). Though this is the case for most wall types that include lime renders. The data for the lime binder in the hempcrete (M11) are from the French LCA and show a particularly high EE because the lime is imported from Spain [14]. Another advantage of earth/straw over hempcrete is that the materials can be found cheaply and locally. At present earth/straw is mainly used for the infill of new timber-frame buildings, though it can be an excellent solution for renovation, especially in combination with the repair of old daub (M15).

3. RESULTS AND DISCUSSION 3.1. Overall scores of wall types

The hempcrete wall is not the only ‘ecological’ wall that gets a mediocre score in the assessment. The cellulose wall (M9) and the monomur of fired clay insulation blocks (M6) do not get satisfactory results either. Blown cellulose is still one of the cheapest and widely used environmental insulation materials, also in renovation. However, due to its low density it has little thermal mass, which brings down the overall score in the assessment. Bringing other parameters into account, e.g. hygroscopicity and thermal bridging, would give cellulose certainly a better overall score than in the present assessment. The monomur may provide a very good decrement delay of 22.5 hours, but shows a very high EE (355 2 2 kWh/m ) and EC (135 kgCO2eq/m ), and is the worst solution of all the 20 wall types (Table 3.).

Fig. 1 Overall scores for 20 wall types (for the results per parameter, see Table 3, p. 4)

The three wall types with the highest overall scores all have exterior insulation, which gives much better scores for thermal inertia (Fig. 1). The walls with woodfibre board on the outside (M20) give the best overall results, whereas more conventional wall types with exterior insulation, e.g. polystyrene (M17), do not achieve a satisfactory overall score due to their high environmental impact. When exterior insulation is out of the question for conservation reasons the earth/straw wall types give 4 the best overall results (M15,M12) . They are probably more compatible with historic timber-frame walls than woodfibre board, especially in the case of wattle and daub walls. Beside their hygrothermal qualities, timber-frame walls with plant fibre infill (e.g. hempcrete, woodchip/lime and earth/straw) provide an excellent decrement delay and are a good solution for thermal bridging and achieving air tightness in leaky old timber-frame buildings [13]. Several studies, e.g. Evrard, show how the dynamic thermal performance of insulation materials can be very different from the ‘steady state’ situations used for thermal regulations, which makes hempcrete walls perform better than expected from simple Rvalues, due to the benefits of hygroscopicity and reduction of thermal bridging [13].

3.3. Dry lining and thermal mass The assessment shows that the widely used ‘conventional’ insulation techniques are amongst the worst performers from a thermal and environmental point of view, with overall scores below 10 out of 20 (M1,M2, M4). This is mainly due to the high EE of new fired bricks and the very low scores for thermal inertia. This is also the reason why the wall with no insulation (M5) gets a better overall score, simply because it does not have an added environmental impact, while it preserves the building’s thermal mass. Some experts therefore believe that it is often preferable not to compromise a building’s vernacular qualities by applying dry lining, but use an insulation render, e.g. hemp and lime, for ‘thermal improvement’ [3]. When the old daub (M3) is kept, dry lining wall types get a slightly better result, especially if glasswool is replaced by woodwool, which is more hygroscopic and therefore more compatible with ‘breathing’ and ‘capillary’ timber-frame constructions. When used in combination with interior clay blocks it achieves a good decrement delay and acceptable overall score of 13.6 (M3b).

3.2. Earth/straw or hempcrete? Amongst French builders earth and straw is less well known than hempcrete, a mix of hemp and lime.

4

Terre-paille or ‘light earth’, a mix of straw and clay earth in very low densities of around 400 kg/m2.

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Table 3 Results all parameters for the 20 wall types

Wall type

Wall number

Overall Width score 1 to 20

cm

Embodied Energy

Embodied Carbon

Resource depletion

Thermal Resistance

Decrement delay

Thermal inertia

kg kWh kea per m² K/w kJ/m²K Score CO2eq Score Score Score h / m² Score Score per m 2 m² per m² per m² per m²

Brick, glassw ool, plasterboard

M1

8.5

26.5

177

8.2

40

7.4 0.02814

10.3

2.65

13.6

5.7

9.5

24

1.9

Clay block, glassw ool, plasterboard

M2

9.7

27.5

144

10.4

36

7.6 0.00528

15.2

2.72

14.0

5.6

9.3

24

1.9

Old daub, glassw ool, plasterboard

M3

11.2

29.5

100

13.4

32

7.9 0.00124

19.4

2.67

13.7

6.5

10.9

24

1.9

Brick, glassw ool, clay block

M4

9.4

32.0

201

6.6

50

6.7 0.02960

10.2

2.75

14.2

7.9

13.2

71

5.7

Old daub, no insulation

M5

10.2

13.0

30

18.0

13

9.1 0.00000

20.0

0.40

1.1

4.6

7.6

70

5.6

Brick and monomur

M6

8.1

49.0

355

0.0

135

1.0 0.10341

6.6

3.13

16.3

22.5

20.0

61

4.9

New daub, w oodw ool, clay block

M7

13.9

32.0

72

15.2

-3

10.2 0.00203

18.0

2.70

13.9

12.4

20.0

77

6.2

Brick (reuse), cork board

M8

13.1

26.0

60

16.0

-3

10.2 0.00000

20.0

2.70

13.9

9.4

15.7

36

2.8

Old daub, cellulose, Fermacell

M9

11.8

28.0

144

10.4

18

8.8 0.00010

20.0

2.69

13.9

8.3

13.8

45

3.6

Old daub, w ood fibre board

M10

14.3

28.0

37

17.5

-13

10.9 0.00000

20.0

2.62

13.5

11.8

19.6

54

4.3

Hempcrete

M11

11.2

31.0

152

9.9

-4

10.2 0.03250

9.9

2.79

14.4

10.8

17.9

58

4.6

Earth and straw

M12

14.7

36.0

85

14.3

-39

12.6 0.00008

20.0

2.77

14.3

16.0

20.0

86

6.9

Woodchip and lime

M13

10.1

45.0

290

0.7

-47

13.1 0.06818

7.8

2.77

14.3

18.6

20.0

62

5.0

Earth/straw , w oodw ool, Fermacell

M14

13.9

25.0

70

15.4

-15

11.0 0.00001

20.0

2.74

14.1

10.6

17.6

63

5.0

Old daub, earth and straw

M15

14.8

38.0

35

17.6

-22

11.5 0.00000

20.0

2.62

13.5

15.3

20.0

81

6.5

Wood cladding, glassw ool, old daub

M16

13.6

29.7

147

10.2

17

8.9 0.00076

20.0

2.80

14.5

8.4

14.0

177

14.1

Polystyrene, old daub

M17

12.2

26.0

124

11.7

39

7.4 0.00522

15.2

2.57

13.2

7.0

11.6

175

14.0

Slate cladding, w oodw ool, old daub

M18

15.0

27.5

120

12.0

-10

10.6 0.00026

20.0

2.68

13.8

10.6

17.7

198

15.9

Woodfibre board, unfired bricks

M19

15.9

25.0

36

17.6

-18

11.2 0.00001

20.0

2.65

13.7

11.4

19.0

176

14.1

Woodfibre board, old daub

M20

16.6

28.0

28

18.1

-20

11.3 0.00000

20.0

2.71

13.9

12.3

20.0

202

16.1

Average

12.4

30.1

120

12.2

9.3

9.4 0.01384

16.6

2.61

13.4

10.8

15.9

88

7.1

3.4. ‘Biosourced’ materials

4. CONCLUSION

Now both France and Germany have their government incentives for renewable building materials, it is interesting to look at the percentage of materials in the wall sections that are ‘bio sourced’, i.e. derived from plant-based sources (Fig 2). The plant-fibre-filled walls have the highest percentages ‘bio sourced’ for both weight and volume.

4.1 Appropriate techniques The aim of the study was to find out what the most appropriate and sustainable insulation techniques are for the renovation of period timber-frame buildings. This means techniques and materials that do not have a negative impact on the environment, or on the structure of a building and its aesthetic and vernacular qualities. The assessment shows there is no one optimum solution which is satisfactory for all these criteria. Though some insulation techniques may be satisfactory from an energy-saving viewpoint, they are not considered appropriate solutions when they have a negative impact on the environment or the building itself. However, despite the reservations of conservationists, exterior insulation may be a solution for walls that are not of great architectural interest. An appropriate material for the exterior insulation of period timber-frame walls is woodfibre board, due to its low thermal conductivity and EE and a good 3 density (168 kg/m ) and vapour-openness. When exterior insulation is not possible earth/straw insulation gives the best overall results. Because this technique is more labour intensive and requires longer drying times (up to several months), it would be interesting to study the wider applications of earth and straw in thermal retrofits of existing buildings, as was done for straw bale in the UK [15]. Furthermore, the labour-intensity factor proposed by Floissac et al. [16] deserves further study and is an interesting socio-economic concept for the development of a

Fig. 2 Percentage of materials ‘biosourced’ per wall type

This corresponds with Fig. 3 which shows that all plant fibre walls store carbon, with the woodchip and 2 lime wall (M13) storing 47 kg CO2eq/m and the 2 earth/straw wall (M12) storing 39 kg CO2eq/m .

Fig 3 Embodied carbon per wall type

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locally sourced and sustainable construction industry using renewable materials. There still is a general lack of reliable technical information on manufactured environmental building materials, and producers of these ‘new’ materials find it difficult to get their products certified [17], e.g. in this study it was hard to find reliable data for expanded cork board insulation. EE and EC figures for cork boards from different sources varied so much it was hard to interpret them. This lack of reliable and comparable data is even more apparent for ‘non-manufactured’ local materials, e.g. earth, straw and other agro fibres.

they provide for thermal insulation and vapour control are often inappropriate. Further research and hygrothermal simulation of different wall types and insulation materials must be carried out to assess which materials are appropriate for historic buildings from a hygrothermal point of view. Hygroscopic materials such as clay and plant fibres can play an important role in moisture buffering [21]. However, the main problem, especially for environmental materials, is to find reliable hygrothermal data which can be used for these simulations [22]. A lot of the results from the assessment are also applicable to new timber-frame buildings and the research model can be adapted to other renovation projects that take the vernacular qualities of buildings into account. Cocon can be used for all types of construction and is normally used to assess a whole building, including its operational energy. In a further case study of several period timber-frame buildings it would be interesting to look at whole buildings, testing several wall types and insulation techniques from the current assessment. Comparing case studies and including hygrothermal simulation could confirm which techniques are more appropriate. Each wall has to be considered individually, also taking climatic parameters (e.g.orientation, solar gain, wind and rain) into account. And building materials should not only be studied for the environmental impact, or the effect they have on the building, but should also be analysed for their influence on indoor air quality and other occupant-related health issues. At present the health issue is largely ignored in the French EPDs.

4.2. Towards consensus on LCA and carbon storage The assessment shows that walls with plant fibre and binder insulation (M12-15) store considerable amounts of carbon. Carbon storage in building materials has a great GHG-mitigation potential, which applies to both renovation and new build [7,12,13,18]. However, further research and scientific debate on calculation methods are needed to establish scientific consensus in the LCA community. Some authors maintain that the inclusion of carbon sequestration only makes sense in a wholly sustainable state of production and consumption [19]. Furthermore, carbon storage in building materials is temporary and depends on what happens at the ‘end-of-life’ of a product. Still, a several centuries old timber-frame houses is probably one of the best examples of a quasipermanent carbon store. The general problem with LCA-based assessment tools like Cocon is the different weighting methods and system boundaries used for LCA data. This can lead to rather different results for the same materials and functional units studied. Future European harmonisation of LCA procedures might resolve some of these problems. However, despite the limitations of LCA and the lack of LCA data for environmental materials, the Cocon database provides reliable figures which have been checked and compared with industry data and other sources [7, 11]. The cross-checking has contributed to the continuous updating process of the database.

ACKNOWLEDGEMENTS I would like to thank Luc Floissac, researcher at LRA in Toulouse (author and developer of Cocon), and the Arts and Humanities Research Council (UK) for their financial support that allowed me to carry out the research. This paper is based on the research for a MSc in Architecture and Advanced Environmental and Energy Studies, at the Graduate School for the Environment, University of EastLondon, January 2010.

4.3. Risks of dry lining in historic buildings

REFERENCES

It is clear that the currently used dry lining techniques have the worst scores in the assessment. This is not only due to their environmental impact, but also because dry lining completely cancels out the benefits of thermal mass. Furthermore, these techniques annihilate the hygrothermal qualities of daub walls and can put the building at risk when condensation and other humidity issues are not properly addressed, as seen in the interviews [20]. When trying to achieve higher levels of thermal insulation and air tightness in historic buildings, inappropriate materials that do not ‘breathe’ can bring huge perils to both the health of the building and the occupant [4]. Builders and architects name humidity control as the main problem in old buildings [20]. However, the study shows that the solutions

[1] Journal Officiel (2009) ‘LOI n° 2009-967 du 3 août 2009 de programmation relative à la mise en œuvre du Grenelle de l'environnement 1’ . [2] Marchal T. (2009) Les enjeux du patrimoine bâti ancien au regard des économies d’énergie’, Journéé de formation Bâti ancien et développement durable, ANVPAH, Paris 16 juin. [3] Cuquel L (2010).Interview 2009, In: H. Valkhoff, The renovation of period timber-frame buildings in SW France, Thesis MSc AEES, Graduate School of the Environment, University of East London. [4] May N. (2006) Traditional materials and energy efficiency, Retrieved 27 October 2009 from: www.natural-building.co.uk. [5] Gielen D.J. (1997) Building materials and CO2; Western European emission reduction strategies, Energie Centrum Nederland.

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[6] Harris C. and Borer P. (2005) The Whole House nd Book; ecological building design and materials, 2 ed. CAT publications. [7] Berge B. (2009) The Ecology of Building nd Materials, 2 ed. Architectural Press. [8] Floissac L. (2009) COCON Comparaison de solutions Constructives de Confort et d’emissions de CO2 version 2.3.0.3. [9] RT-2007 (2007) Réglementation Thermique des bâtiments existants. [10] INIES (2009) La base de données française de référence sur les caractéristiques environnementales et sanitaires des produits de construction, CSTB, Retrieved 27 October 2010 from: http://www.inies.fr/ [11] Cocon base de données (2009), Laboratoire de Recherche en Architecture (LRA) de l’Ecole Nationale Supérieure d’Architecture de Toulouse. [12] Cornillier C., Vial E. (2008) L’Analyse de Cycle de Vie (ACV) appliquée aux produits bois, IXème Colloque Sciences et Industrie du Bois, 20 & 21 novembre. [13] Bevan R., Woolley T. (2008) Hemp lime construction ; a guide to building with hemp lime composites, IHS BRE Press. [14] Boutin M.P., Flamin C., Quinton S., Gosse G. (2006) Etude des characteristiques environnementales du chanvre par l’analyse de son cycle de vie INRA, Ministère de l’Agriculture et de la Pêche. [15] Le Doujet K. (2009) Opportunities for the large scale implementation of straw based external insulation as a retrofit solution of existing UK buildings MA Thesis, University of Cambridge. [16] Floissac L., Bui Q.B., Colas A.S., Marcom A., Morel J.C. (2009) How to assess the sustainability of construction processes, Fifth Urban Research Symposium, Cities and Climate Change, Marseille. [17] Conteville and Den Hartigh C. (2008) Les écomatériaux dans la rénovation thermique des logements en France, Amis de la Terre, Paris. [18] Amato (1996) cited in: Hammond G., Jones C. Inventory of Carbon&Energy (ICE), University of Bath, 2008. [19] Harris R. (2009), Is Timber a sustainable building material?, Lecture notes AEES Module C-3 study book, Graduate School of the Environment, CAT/UEL. [20] H. Valkhoff (2010) Interviews with building professionals in Midi-Pyrénées, In:, The renovation of period timber-frame buildings in SW France, Thesis MSc AEES, Graduate School of the Environment, University of East London. [21] Padfield T. (1998) The role of absorbent building materials, PhD TU Denmark. [22] Valkhoff H., Floissac L. (2011), rapport Hygroba, tâche 2, LRA, CETE-EST (in preparation).

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The Thermal Behaviour of Cross-Laminated Timber Construction and its Resilience to Summertime Overheating Owen JOWETT University of Cambridge, Cambridge, UK ABSTRACT: This study is concerned with the thermal performance of cross-laminated timber (CLT) and the impact of increased peak temperatures. It explores the passive potential of the Murray Grove housing project by Waugh Thistleton Architects. On-site measured data from two apartments with contrasting orientations along with occupant surveys were used to calibrate a dynamic thermal model. Comparative modelling of the thermal performance of CLT construction with a concrete frame structure showed similar thermal performances under current conditions. Under projected peak conditions for 2050 the concrete frame scenario reduced overheating o compared to CLT, although still showed over 11% annual hours over 25 C. Occupant surveys indicate very low levels of spacing heating and summer window opening patterns, which show all-day cooling, was required during summer 2009. The building is naturally ventilated and the simulated data also suggest this will cease to be sufficient as temperatures rise. The use of factory-based manufacturing produces engineered timber to exact tolerances and the airtightness results were around a half of current UK requirements. The findings indicate that extensive use of CLT, especially in buildings whose form is inherently thermally efficient, is likely to produce problems of overheating. However they also show the same is true of buildings using heavyweight construction. Keywords: Mass Timber, overheating, housing, thermal mass,

1. THE STUDY This study is concerned with the thermal performance of cross-laminated timber (CLT) and the impact of increased peak temperatures. It explores the passive potential of the case study building (the Murray Grove housing project), particularly its resilience to summertime overheating. The study incorporates the perceptions and actions of residents to assist the understanding of current and potential adaptive behaviour. On-site measured data will be used to calibrate the dynamic thermal model. Modelling comparative data on the environmental performance of the CLT construction with a standard heavyweight structure will indicate relative performance, as well as the case study building’s free running potential in different scenarios. The implications of the findings for future environmental design will be noted.

for Sustainable Homes (Communities and Local Government, 2007) that did not mention summertime heat gain, focusing instead on air-tightness and insulation. The impact of the predicted rises in summertime peak temperature (Jentsch et al, 2008) is also worthy of investigation, given the associated health risks amongst certain groups. During the 2003 August heatwave, in London, for example, deaths among people aged over 75 rose by 60% (Department of Health, 2009).

2. BACKGROUND The context of Britain’s housing shortage and the recent targets for new homes bring into sharp relief the need for innovation in construction (Barker et al, 2009). The Community and Local Government’s Adaptation Plan (Communities and Local Government, 2010) states that: “We have made it a requirement on the builder to consider heat gains as well as heat losses in domestic buildings, to manage energy demand”. This explicit statement is a marked change from previous legislation such as the Code

Figure 1. Murray Grove housing by Waugh Thistleton Architects

The Murray Grove housing project (Fig. 1) is in Hoxton, East London. Completed in 2009, this ninestorey building is the world’s tallest residential timber building. It comprises 29 apartments located at corners surrounding a double core, with separate stairs and lifts for the different tenures (nine are

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socially rented, 20 privately rented or owned) (Fig. 2). It is located within London’s Urban Heat Island (UHI) (Watkins et al, 2007) area and is, therefore, at increased risk of overheating. During the design process for this CLT building cost-benefit analyses were undertaken on a number of variables, including construction time and cost, comparing it to a standard concrete framed construction. It was estimated, for example, that the construction period using concrete would be 72 weeks and the CLT project was completed in 49 weeks. However, there is no evidence to suggest that the projected thermal performance of the building was included in these analyses, nor that the emerging research findings were incorporated. Palmer et al’s (2004) work, for example, showed that cooling using a combination of thermal mass, night cooling and user controlled solar controls reduced overheating more efficiently than other passive methods. The structural form of CLT buildings is similar to those of pre-cast concrete panels as both materials have multi-lateral strength, with walls acting as beam (Yates et al, 2009). The building’s ‘honeycomb’ structure means that almost all internal walls are structural CLT with a U-value of 0.62 Wm2/h, compared to 1.69 Wm2/h for a typical stud wall. The density of CLT is 500 kg/m3, compared to up to 2400kg/m3 for concrete and the heat conductance of the 128mm 3-ply wall panels is 0.13 W(m2K). The specific heat capacity of CLT is 2100 J/kgK, compared to 3300 J/kgK for concrete (McMullan, 2007).

retention, rather than passive cooling (Pokorny et al, 2008). White (2010) indicates that super-insulated buildings simulated using current UK climate data (CIBSE DSY 2005) failed to meet requirements for overheating. However, Orme et al (2005) showed that reducing internal gains and providing operable solar shading were effective in reducing overheating hours. The amount of solar gain plays a key role in determining the building’s passive potential. The combined kitchen, living room and dining areas have windows on two adjacent facades and are fairly narrow plan, so sunlight strikes the back wall as well the floor. Because of fire resistance concerns the timber is not exposed internally, with 15mm of plasterboard lining the interior throughout, and double this thickness protecting the lift shafts. This reduces the ability of the thermal mass to regulate the internal environment. These spaces also receive most of the apartments’ internal gains from occupancy, cooking, pets and electrical equipment, and are, therefore, influenced by occupancy patterns. As the building contains a mixture of flats, ranging from 4-bedroom family apartments to 1bedroom penthouses there is variation in occupation profiles and internal gains.

 

 

Figure 3. External Wall Detail (Thompson, 2009)

The building is naturally ventilated, and the double aspect corner apartments allow crossventilation, although the internal fire doors with closers may limit this. The internal floor construction contains a 55mm unexposed screed (Fig. 3).

  Figure 2. Typical Upper Floor plan (Thompson, 2009)

Building codes can influence progress with CLT. In Vienna, for example, the Muhlweg Residential Development followed changes to the local regulations that encouraged timber construction (Teibinger, 2008). The use of factory-based, computer-controlled manufacturing produces engineered timber to exact tolerances and reduces structural movement. The timber used for the case study building was grown and processed in Austria, where harsher winters have led to heavily insulated buildings with high levels of air-tightness. The development of supersealed mechanically ventilated homes under the Passivhaus system is based upon principles of heat

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3. METHOD This experiment combined measured and simulated data, using on-site readings to calibrate the dynamic thermal model. It sought to determine the building’s free-running potential in different scenarios.

 

3.1. Environmental Monitoring Data were collected using data logging sensors in two apartments and an occupant survey, where all 29 apartments were invited to take part, using letters and direct contact. The data loggers monitored room temperature and relative humidity for 7 days from 18:00 on 08/04/10, taking readings at 15-minute

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intervals. The apartments each contain a condensing boiler and radiators for space heating. Both private and socially renting tenants are responsible for their energy bills. Data loggers were placed at six locations across the two apartments (Figure 4).

 

       

 

Figure 4. Data Logger locations – Flat 8, Third Floor (left) and Flat 14, Seventh Floor

The apartments chosen allowed a number of conditions to be assessed. Flat 8 is located at the SW corner of the third floor, has three bedrooms and is occupied almost constantly. The residents (two adults, two children and three dogs) are joined on most days by relatives and friends. This maintains a constant level of internal gain, particularly in the living room/kitchen space, which contains a large CRT television and sound system, alongside the open kitchen with associated cooking gains. Flat 14 is located at the SE corner of the seventh floor with two bedrooms, both facing east. The occupants work full-time, so the flat is generally empty during the day. Despite this, they only recall 2-3 times when the heating was required during the winter.

 

 

Figure 5. Data Logger results (Flat 8, above, and Flat 14)

The monitoring period was mild and dry, and neither apartment used central heating during this time. The results, therefore, indicate the free-running potential of the building, with heating requirements being met by internal and solar gains. The sensors in Flat 8 recorded higher average temperatures than those in Flat 14 due to the southwest orientation and more consistent occupation. The living room/kitchen sensor showed spikes caused by cooking, although these were isolated, possibly because of windows being opened for odour ventilation. The constant occupation and lack of trends suggest that the occupants use window opening to regulate their environment. The sensors in Flat 14 (Fig. 4) indicated clear patterns relating to use. The bathroom sensor recorded spikes in temperature and humidity once a day; the occupants using the shower before work. Otherwise the temperature remained between 22-24ºC due to the room’s position enclosed within the plan. The sensors in the living room/kitchen space and the bedroom recorded inverse patterns of use. The weekday period showed the living room/kitchen area’s temperature responding directly to external conditions. This is due to the east and south facing glazing in the room. The bedroom, by contrast, is warmed by occupancy overnight and then cools during the day. 3.2. Occupant Survey All 29 flats were visited, and, following two visits, 10 residents were identified to take part in the survey, 4 from socially rented apartments and 6 from those privately owned or rented. All residents had lived in the building since it opened in January 2009, and they were questioned on their recollections of its thermal performance during the previous year. They were asked for an air-quality rating (Yarnold, 1947) and to rank rooms by temperature in both summer and winter. Seasonal window opening patterns were also determined to investigate adaptive thermal comfort. All but one reported opening windows in one or more rooms during winter to expel stale air. The occupant survey and results show patterns of adaptive behaviour (fig. 6). One couple had never used their central heating and their energy bills were only £85 per quarter. These respondents had young children and, therefore, occupation was fairly constant. Although these respondents opened windows in all rooms during the summer, the longer occupation period does not appear to have an effect on adaptive behaviour when compared to the shorter occupation times of the private flats. All but one of the respondents with a southerly aspect to their living room/kitchen space reported that this was their warmest room during the summer. Residents with north facing living room/kitchen spaces generally found that their east or west facing bedrooms were warmer. This suggests that solar gain has a strong influence on the internal environment, and that during the summer months this overrides internal gains. These trends are reversed during the winter, when all respondents reported that the living room/kitchen spaces were

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warmer than east or west facing bedrooms. This would suggest that during these periods, internal gains from occupation, cooking and electrical appliances are contributing to space heating, so unoccupied spaces were cooler.

 

   

 

 

  Figure 7. Summer and Winter internal and solar gains

Figure 6. Thermal Comfort questionnaire results

This is supported by the simulated data (Fig. 7) which show internal gains from night-time occupation in the bedroom of Flat 14 that remain constant throughout the year and variation in solar radiation and its influence on dry resultant temperature. 3.3. Building Simulation The building was modeled in IES-VE simulation software to allow predicted climate data (DSY 2050) to be used for the building’s life expectancy. These data were generated using the CCWeatherGen programme, developed by the Sustainable Energy Research Group at the University of Southampton. The software uses UK Climate Impact Programme data for Medium-High emissions levels to ‘stretch’ weather files.

The building fabric was modelled using detail drawings and manufacturers’ specifications to ensure correct thermal insulation and resistance. It underwent post-completion air-tightness testing, in accordance with the Code for Sustainable Homes (Communities and Local Government, 2007), and the results, ranging from 2.02-3.82 m3/(h.m2) @ 50 Pa, have been applied to the appropriate spaces. They highlight the building’s potential for heat conservation, as the requirements of Approved Document L1A (2006) stipulate an air-permeability of 5 m3/(h.m2) @ 50 Pa. PassivHaus requirements (Pokorny et al, 2008) are less than a fifth of this, however, showing that investment in the building fabric could deliver further increases in performance. Continued study could determine the benefits of reaching PassivHaus standards in reducing energy consumption and the overheating risk of airtight construction in a warming climate. Four different scenarios were simulated (Figure 8). As stated, throughout the design process CLT construction was compared with traditional concrete, in terms of cost and construction time, and via the simulation, the thermal performance of each has now been predicted. The heavyweight construction simulation featured the same U-values and air infiltration figures as the existing fabric model to focus the results on the desired variable. Figure 9 identifies the construction material used in the model.

 

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time temperatures remaining above those for heavyweight construction. These trends are apparent, although to a lesser extent, in the 2005 data for Flat 14. This could result from only receiving direct solar gain before midday.

  Heavyweight Construction

Building Construction Scenario

Existing Fabric

External wall build-up

Fibreboard tiles, Cavity, Polyurethane Board, CLT, Gypsum plasterboard 2

0.1633 Wm /h Internal wall build-up

CLT Flat 8 West Bedroom

2

Brickwork outer leaf, polyurethane board, cast concrete, plaster 2

Plaster, brickwork (inner leaf), plaster 2

1.6896 Wm /h

Synthetic carpet, screed, polyurethane board, CLT, Cavity, polystyrene, gypsum plasterboard 0.1424 2 Wm /h

Glazing

 

0.6163 Wm /h

0.1633 Wm /h Floor buildup

Gypsum plasterboard, CLT, Gypsum plasterboard

Synthetic carpet, screed, polyurethane board, cast concrete polystyrene, plaster 2 0.1424 Wm /h

Low-e Double Glazed Windows (2001 Building Regulations) Uvalue= 1.9773

Infiltration rate

Infiltration Rate = 0.12 ach (based on postcompletion testing)

Heavyweight construction

Free running (no space heating) with window opening regimesbased on CO2 concentration and air temperature (Doors all modelled as closed, windows programmed to open when o o 20 C< >25 C or when 800ppm< >1200 ppm

Occupied 2 people per bedroom 23:0008:00, 3 people, a computer and lights in living room 08:0023:00 + plus 30mins+30 mins of 1.6kW latent cooking load @ 12:30 and 19:00

Flat 14 East Bedroom File London dsy 2005 annual clt .aps London dsy 2050 annual clt .aps Heavyweight Flat 8 West Bedroom

Figure 8. IESVE Simulation Characteristics Existing Fabric

File London dsy 2005 annual clt .aps London dsy 2050 annual clt .aps

London Heathrow DSY 2005

File London dsy 2005 annual hvw .aps London dsy 2050 annual hvw .aps

London Heathrow DSY 2050

Flat 14 East Bedroom File London dsy 2005 annual hvw .aps London dsy 2050 annual hvw .aps

(Halls, landings, lifts and stairwells unoccupied)

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Figure 10. Simulation Results – Overheating Tables Dry-bulb temperature (°C) - hours in range

Figure 9. IESVE Simulation Scenarios

Dry Resultant Temperature was used in the simulation model as it combines air temperature, radiant temperature and air movement and is therefore closely associated with thermal comfort, particularly in a cross-ventilated space where air movement may be high. The simulation results are for two of the rooms monitored: the west-facing bedroom of Flat 8 on the third-floor and the east-facing bedroom of Flat 14 on the seventh-floor. These rooms were chosen as they are similar in size and, unlike the living room/kitchen spaces, are single aspect. The results for Flat 8 show that during peak summertime periods the CLT reaches temperatures of 1-2ºC higher, with nighttime lows being 2-3ºC lower, than the heavyweight construction. This greater range of temperature is also evident when using the 2050 climate data, with peak temperatures being higher for CLT and night-

File UK-Heathrow DSY medhi02050.epw LondonDSY05

> 25.00

> 28.00

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Figure 11. Climate Data – Overheating Tables

Both constructions show dramatic increases in overheating using the predicted climate data. Under 2005 conditions they both fall well within the limit of 5% of annual hours over 25ºC, but the predicted data show this increasing to 12.7% for CLT and 11.6% for heavyweight construction. Overheating above 28ºC is also within the 1% of annual hours when modeled with 2005 climate data. In 2050 this rises to 2.8% for heavyweight construction and 3.9% for CLT. These results suggest that, although there is a difference between the increase in overheating between CLT and heavyweight construction, both experience significant increases, which limit the

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capacity of the building form and cross-ventilation to provide cooling. The implication is that resilient, highdensity housing must allow increased ventilation and control solar gains.

4. CONCLUSION The case study building provides an intelligent response to current concerns and the ecological advantages of CLT construction are undisputed (Thompson, 2009). The findings indicate that extensive use of CLT, especially in buildings whose form is inherently thermally efficient, is likely to produce problems of overheating. However they also show the same is true of buildings using heavyweight construction. A dynamic thermal simulation of BaleHaus at Bath (White, 2010) showed summertime overheating was already a problem with between 5.42-5.97% of hours being over 25ºC (CIBSE, 2002). Using highdensity internal elements has been shown to increase the thermal capacity of timber-framed buildings and this principle applies equally to CLT construction (Szalay, 2004). The monitored data begin to undermine the value of Passivhaus design in high-rise design in the UK. The case study building falls short of all technical standards required for certification, but shows that by exceeding current Building Regulations energy usage can be reduced dramatically. The combination of reduced external walls and the UHI effect mean that air-leakage is reduced and occupants’ adaptive thermal comfort is not undermined by using window opening to control air quality. The building’s air-tightness and high level of insulation, combined with the lightweight construction, mean the building is susceptible to summertime overheating. The results of the occupant questionnaire suggest further attempts at summertime cooling may be ineffective. These findings are supported by the simulated results, which show passive cooling by cross-ventilation will cease to reduce internal temperatures during increasing summertime temperatures. The space heating demand of the building is currently met with combination boilers. As the occupant survey suggests this is largely unused for heating. Further study could determine whether the cost of installing a traditional heating system could have been more effectively spent on water heaters, additional insulation and increased air-tightness, if the internal and solar gains are sufficient. Using internal gains to contribute to space heating, particularly in family apartments with longer occupation hours, could provide substantial savings in energy use.

 

5. ACKNOWLEDGMENTS I would like to thank Andrew Waugh (Waugh Thistleton architects), David Gregory (Metropolitan Housing Trust) and Professor Alan Short for their support during this study. Particular thanks are due to the tenants who welcomed me into their homes and answered my questions so patiently.

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6. . REFERENCES [1]

Binderholz Bausysteme GmbH. (2010). Binderholz CROSS LAMINATED TIMBER BBS. Salzburg: Binderholz Bausysteme GmbH.

[2]

CIBSE. (2002). CIBSE Guide J - Weather, solar and illuminance data. The Chartered Institution of Building Services Engineers. London: CIBSE Publications.

[3]

Communites and Local Government. (2007). Building A Greener Future - Policy Statement. London: CLG Publications.

[4]

Communities and Local Government. (2007). Code for Sustainable Homes : A step-change in sustainable home building practice. London: CLG Publications.

[5]

Communities and Local Government. (2010). Departmental Adaptation Plan. Communities and Local Government Publications .

[6]

Department of Health. (2009). Heatwave Plan for England. London: Department of Health.

[7]

Jentsch, M. F., Bahaj, A. S., & James, P. A. (2008). Climate change future proofing of buildings – Generation and assessment of building simulation weather files. Energy and Buildings , 40 (12), 21482168.

[8]

Kovats, S., Johnson, H., & GrifÞths, C. (2006, Spring). Mortality in southern England during the 2003 heat wave by place of death. Health Statistics Quarterly , 68.

[9]

McMullan, R. (2007). Environmental Science in Building. Basingstoke: Palgrave Macmillan.Orme, M., Palmer, J., & Irving, S. (2005). Control of Overheating in Well-Insulated Housing. CIBSE. Faber Maunsell Ltd.

[10] Palmer, J., Orme, M., & Irving, S. (2004). Control of Overheating in Housing - Cooling Housing in a Warming Climate. Future Housing Forum. Faber Maunsell. [11] Pokorny, W., Zelger, T., & Torghele, K. (2008). Construction and Building Physics. In T. Waltjen, Details for Passive Houses (pp.13-39). New York: SpringerWien. [12] Szalay, Z. (2004). Are Timber Buildings Really Lightweight? Budapest: Department of Building Energetics and Building Services . [13] Teibinger, M. (2008). Urban Timber Houses in Vienna (Vol. 18). International Association for Bridge and Structural Engineering. [14] Thompson, H. (2009). A Process Revealed. London: Fuel. [15] Vessby, J., Enquist, B., Petersson, H., & Alsmarker, T. (2009). Experimental study of cross-laminated timber wall panels. European Journal of Wood and Wood Products (67), 211-218. [16] Watkins, R., Palmer, J., & Kolokotroni, M. (2007). Increased temperature and intensification of the urban heat island: complications for human comfort and urban design. Built Environment , 33 (1), 85-96. [17] White, C. (2010). Thermal Mass Properties of Monolithic Timber. London: TRADA. [18] Yarnold, K. W. (1947). Factors Affecting Warmth Comfort and Stuffiness in Domestic Rooms. Journal of Hygiene , 45, 434-442. [19] Yates, M., Linegar, M., & Dujic, B. (2009). Design of an 8 storey Residential Tower from KLH Cross Laminated Solid Timber Panels. London, Ljubljana.  

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

PCM Analysis as a strategy in passive thermal conditioning in floors Isabel CERÓN1, M. Carolina HERNÁNDEZ-MARTÍNEZ1, Carmen MONTEJO1, Javier NEILA1 1

Department of Construction and Technology in Architecture. School of Architecture. Universidad Politécnica de Madrid, Madrid, Spain

ABSTRACT: Since 2005, the ABIO research group works on the development of solutions in architecture that incorporate Phase Change Materials (PCM) into constructive systems and materials as part of the building’s thermal conditioning. One of the strategies employed for thermal conditioning has been the direct incorporation of PCM in pavements, having now developed several prototypes. ABIO research group has reached certain conclusions as a result of the use of PCM as passive thermal conditioning. The development process of one of these systems is detailed in the article below, as well as the analysis of benefits and difficulties encountered in the process of integration of PCM in architecture and its performance as passive thermal conditioning agents, before, during and after the construction of the building. Different aspects have been taken into account, such as architectural integration (construction), chemical analysis, costs and thermal analysis. Keywords: Phase change materials (PCM), energy storing, heat storage, flooring, passive strategy.

1. INTRODUCTION In 2005 the Universidad Politécnica de Madrid took part in the “Solar Decathlon” [1] contest with the “Magic Box” prototype. During the competition, the first approach of the research group to phase change materials (PCM) and their benefits was put in place as a strategy for latent heat storage integrated into the materials and constructive systems of the prototype. As a consequence of this first experience, different prototypes were developed for their incorporation into raised-technical floors for housing, with encouraging results regarding the possible benefits of their application. In 2007, the ABIO (Arquitectura biolclimática en un entorno sostenible) research group participated in the INVISO project [3] (Industrialización de Viviendas Sostenibles). The main aim was to develop a research method to create a catalogue of architectural bioclimatic strategies. The research method was developed in a tree structure with six main branches one of which was energy storage. Regarding passive architectural strategies, ABIO identified thermal storage (weather sensitive or rather latent heat) as one of the most interesting strategies because of its potential development and application in construction. In so far as latent heat storage research was concerned, the main objective of ABIO was to identify every possibility to introduce phase change materials (PCM) in traditional constructive solutions as well as new application proposals. The development of the strategies included all kinds of different possibilities to introduce the PCM, directly into the system macroencapsulated or micro-encapsulated in the material during its manufacture or even soaked over the material once finished. All these options generated a wide range of design proposals appropriate for its use in horizontal and vertical enclosures as well as in building installations.

2. LATENT HEAT STORAGE STRATEGY 2.1. Latent heat storage Several authors have studied the thermal phenomenon that takes place during the material’s process of phase change [4] [5]. This relates to the steps between solid, liquid, gas or even an emulsion phase that appears in some materials. When one of these processes is reverted the energy stored is released and completes the material’s thermal cycle. The temperature of the material remains constant during these phase changes as the energy is being used in the break down of molecular bounds. This is the reason why these processes of energy charge and discharge occur in a slow and constant manner, allowing for its use in passive thermal conditioning. 2.2. Passive thermal conditioning of flooring In winter conditions, heat goes up due to convection, flowing from the floor up to the ceiling of a room. This mechanism assures that the temperature gradient is appropriate to obtain ideal comfort conditions. If the floor works too as an energy collector, then the location and dimension of windows would be directly related to the quantity of energy that the floor may store, as windows are the main entrance of solar radiation, and a main passive energy resource. This process suggests the effectiveness of flooring systems as passive thermal conditioning. The difficulties encountered in the development of simple passive thermal conditioning systems are identical to those encountered in the production of any pavement, such as high mechanic material resistance, long life endurance, an acceptable esthetical preservation, reasonable economic costs, preference for light weight materials to reduce weight on the structure and also high speed warming rates (thermal diffusivity). All these needs actually spell out the list of possible solutions.

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In general, for the installation of discontinuous pavements in interiors, there are two main traditional systems. The first one and most common is to install the pavement, a floor tile or stone, with an adherent layer directly over the intermediate layer (thermal and/or acoustic insulation, waterproofing, mortar or sand base) that evens the surface of the floor structure. The second one, a raised-technical floor, would lift the walking surface from the slab, by means of a substructure that creates a useful intermediate space for installation tubes or increasing thermal or acoustic insulation. To date, ABIO has developed three different prototypes, all of them sharing one common element design: a ceramic tile which carries underneath a metal container with PCM Two of the prototypes were designed to be incorporated as a raised-technical floor, while the third one was intended to be installed directly on the floor.

3. PROTOTYPE DESIGN 3.1. Paraffin mixtures as PCM

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In all three cases mentioned above, the paraffin was used as PCM, substance that changes its phase from solid to liquid and vice versa in a temperature gap between 10ºC and 30ºC and latent heat value between 90 and 130 kJ / kg. The choice of material was made with due regard to its compatibility with high mechanic resistance metal capsules, easy handling, non corrosive, chemically stable, not wearing out with time and having its phase change temperature gap in a lapse according to normal building interior comfort needs. The PCM was not supplied encapsulated in any of the cases. This kind of PCM substances can be pure or mixtures, both with a paraffinic composition. Because of their organic origins, in some cases (when there is no proper study of the mixture) there may appear compounds that volatilize in contact with the air. This may cause changes in its composition as well as in its thermal, physical and chemical properties. Therefore, it is recommended to purchase these substances at recognized laboratories, which is a difficult task, having to request from suppliers guaranteed products [6], [7] with a corresponding differential scanning calorimetric analysis (DSC) (Fig.1).

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Figure 1: DSC performed with used PCM substance in the tile and cylinders prototype

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3.2. Encapsulation The “container design” needed to fulfil a series of requirements such as high resistance against punctual stresses, adequate thermal conductivity and full compatibility with the PCM. All these restrictions led at the beginning to choose an embossed steel metal container. Two of the prototypes incorporate a floor tile that carries underneath a rectangular metal container with 41 structural stamped cells and a covering sheet welded to it, with a coating of oven cooked conductive paint that seals the whole container. The main problem of this choice was to have an adequate seal of the fissures along the container welding, as the substance in its liquid phase could leak. A secondary problem was the increase of weight that the container could add to the system. The next evolution of the prototype was a galvanized steel container, a high thermal conductivity material but rather lighter than the previous embossed steel one. This meant a considerable decrease in costs and container’s wall thickness, leading to lighter structures and better heat transmission. The encapsulation of the substance can be done in two ways. On the one hand, it can be pre-filled, in factory, where the safety for the PCM integrity is higher, and the hand work is cheaper. In this case the whole tile can be transported ready finished to the construction site where it can be installed much faster, although the weight of 32 kg each finished tile makes it more difficult to handle them. On the other hand, the encapsulation can be done directly at the construction site, in-situ. In this case, to be able to work with the paraffin, it must be in liquid phase, which means that the substance has to be heated up or delivered already hot, with a limit of time for the encapsulation and poor safety of the PCM integrity against exterior contamination. This procedure is obviously very complex and slow. In two of the strategies developed the intention was to encapsulate the PCM underneath the technical floor. In order to achieve this objective the encapsulation requirements for the tiles had to change slightly from those of the “container design”. While the tile’s finished side was within any user’s reach, the capsules underneath would need to be handled only by authorised personnel, less likely to be exposed harm. The resistance requirements would be limited to chemical compatibility of the material with PCM and the environment. The most important feature for these systems is to optimize the heat transmission and the container’s geometry with a bigger contact surface to increase heat exchange between air and PCM. The first prototype for the Solar Decathlon 2005 contest, the so-called “Magic Box” consisted of a pile of two to three flat plastic rectangular containers, whose size was 28cm x 48cm x 2cm. The prototype incorporated a gap of 2cm between each of them to allow the necessary air flow. The second prototype, developed for the Solar House-Energy Agency Office Building at RivasVaciamadrid, after the analysis of the previous one, evolved into a change of shape and material. With aluminium cylinders, 13cm high and 5.5 cm diameter, thereby achieving a volume reduction of each container and an improvement on heat transmission to make them more efficient.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

3.3. Pavement Selection The pavement used should be made out of a conductive material in order for energy to travel from the surface of the tile to the PCM underneath. The floor materials in the market are mainly wood, textiles, polymeric, stones and ceramics. Among these materials only ceramics and stones answer better to the previous statement. The study centred its attention on two types of ceramic finish, namely, porcelain and rustic stoneware. The porcelain stoneware has a high heat conductivity rate [8] in comparison with other pavements. The tile’s thickness is generally under 1cm, thereby improving heat conductivity. Rustic stoneware is fired clay and due to its production process each tile may have a variation in size of up to 5mm in all three dimensions. This last feature makes its use difficult and may delay the assembly of the system. It is two times thicker than the porcelain stoneware and has up to 0,2 W / m · K lower heat conductivity rates. On the other hand, rustic stoneware’s price can be up to 100 € / m2 cheaper.

Figure 2: Explanatory section of system composed by porcelain stoneware tile with metallic capsule containing PCM and plastic containers with PCM under raised-technical floor.

This system was designed as part of the thermal conditioning strategy in the solar house “Magic Box” that represented the Universidad Politécnica de Madrid in the Solar Decathlon international contest in 2005 [2]. The strategy involved, first, installing the tile prototype in the raised-technical floor and in the space below introducing piles of two to three rectangular plastic containers filled with PCM distanced between themselves by strips of 2cm (Fig.3) to permit the air flow. The plenum under the tiles had a height of 30 cm.

3.4. Material simulation In the current conventional software market (Ecotec or Design Builder) for energy efficiency simulations in buildings, phase change materials lack established standards of analysis. This is the result of an absence of empirical data, so far due to reduced PCM applications in construction. Some of the top companies in PCM integrated systems have developed specific software for their products. Examples of this software are PCM Express (rendering coating and Pladur divisions), Cristopia (heat storage tanks) and DuPont that has developed an arithmetic engine for their product (dividing walls). Other existing complex arithmetic engines were designed to solve thermodynamic problems such as Trnsys, ESP-R or Energy Plus (E+), but they involve a big technical difficulty that requires an exhaustive training and practice.

4. SOLUTIONS CATALOGUE 4.1. System composed by porcelain stoneware tile with metallic capsule containing PCM and plastic containers with PCM under raisedtechnical floor. (Fig.2)     

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Figure 3: Photograph of system installed in “Magic Box” Solar house.

The system was designed to activate the PCM by means of air flow through the space under the technical floor. The air went into the room through a combined system of grilles and lockgates. They worked depending on the conditioning requirements for each moment of the day, allowing air from inside or outside the building and/or getting it back in. Additional turbines were installed underneath the technical floor to increase the air flow. Data obtained from thermal conditioning analysis proved that plastic containers geometry and its encapsulation material were not working properly, as they did no allow a proper air flow. In some areas, the storage substance was not liquefying or solidifying completely in each of the cycles, reducing efficiency considerably in the whole system. Assuring the complete material’s phase change is essential in these systems. For this reason, the container’s shape and material are key for the effectiveness of the system. This system is appropriate in new construction, since clear heights and ventilations channels are needed for it to work properly. Instead its incorporation in restoration works has several limitations, even though its construction and installation are quite simple, carrying no special extra costs. 4.2. System composed by porcelain stoneware tile with metallic capsule containing PCM and cylindrical containers with PCM under raisedtechnical floor. (Fig.4) In 2009, the UPM was entrusted with the reproduction of the “Magic Box” prototype for Rivas Vaciamadrid City hall [9], with design improvements in the building’s passive conditioning system. The main modifications were introduced in the raised-technical floor. This system consists of three elements, namely, a porcelain stoneware tile with a galvanized steel capsule attached underneath containing PCM, raised

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22cm from the slab on plots, aluminium cylinders filled with PCM and a 6cm thick expanded polystyrene (EPS) tray laid under tiles where the cylinders are installed [10].

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

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Figure 4: Explanatory section of system composed by porcelain stoneware tile with metallic capsule containing PCM and cylindrical containers with PCM under raised-technical floor.

The first improvement step with regard to previous prototypes was to check and evaluate the encapsulation element used under the technical floor. The search for a material with higher thermal transmission rates, minimum thickness, cheap and present in industrial processes to facilitate production, resulted in choosing aluminium. In a similar way, capsules geometry led to a change of shape and compactness analysis (relationship between surface and volume of geometric shapes). A greater surface means greater heat exchange capacity between interior and exterior and a greater volume means greater heat storage capacity. Subject to these conditions, the cylinder was chosen against the sphere (with ideal shape factor) due to its stability and its availability in standardized cheap industrial processes. The design of the EPS cast was done to set the cylinders. But at the same time it works as an element that increases thermal and acoustic insulation in horizontal divisions. The cast installation onto the surface underneath the technical floor covered the surface and filled it with gaps for substructure plots. This piece works as an egg box, keeping the distance and stability of cylinders and providing safety (Fig.5).

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Figure 5: Computer Graphics of cylinder and cast system in technical floor at Rivas Vaciamadrid.

The tile prototype with metal container was checked to decrease the total weight of the piece, and increase its physical capacity, eliminating the structural stamped cells of the initial prototype. It was turned into a container made of galvanized steel sheet of minimum thickness, reducing weight considerably. This solution involved independence between capsule and tile and a squared plastic crosshead was developed to fit both parts together (Fig.6). The benefit of this intermediate element is to assemble the system in two independent steps, with less weight involved in the handle of pieces so it is easier and faster to build, and at the same time it works as a joint between tiles. Although, this is a very thin separation element, it avoids the direct contact between the tile and the PCM container underneath. It should be noted that even the tiniest amount of air in between the tile and the PCM container, would cause a discontinuity in the thermal flux from the tile’s surface to the metallic capsule, resulting in energy being lost. To avoid this phenomenon an adhesive mortar was introduced to seal and keep continuity.

Figure 6: Photograph of porcelain stoneware tile and plastic crosshead at Rivas-Vaciamadrid

With regard to the physical installation of the prototype’s part located under raised-technical floor, it is necessary to analyse the space where it will be installed to ensure correct and efficient air ventilation. In addition, a maximum of 1cm distance is required between the part underneath the tiles and the cylinders, so that the air flow would be kept going around the cylinders and not above them, as fluids tend to go through the path which requires less energy to flow. For the same reason, cylinders are arranged in a diamond shape, facing the flows direction, having this way uniform ventilation all over the technical floor space. (Fig.7).

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 7: Photograph of raised-technical floor system, without porcelain stoneware tile, installed at RivasVaciamadrid

About the grilles and lockgates ventilation system, these keep the same working arrangement as the initial “Magic Box” project [2]. 4.3. System composed by rustic stoneware tile with metallic capsule containing PCM. (Fig.8).   

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Figure 8: Explanatory section of system composed by rustic stoneware tile with metallic capsule containing PCM.

Clear height limitations in restoration projects lead to variations on the prototypes for pavements. As raised-technical floors were not always a possibility to work with, the need for a simpler system to store heat became clear. In this case, the tile with the metal PCM container was placed directly over the insulation layer that covers the floor structure. For this prototype the tile finish used was rustic stoneware attached with the same metal container as the “Magic Box” project, and filled with paraffin as phase change material (Fig.9). The insulation layer made of Rockwool isolates thermally the floor structure to avoid heat loss.

Figure 9: Photograph of rustic stoneware with metal container prototype.

system installed in real winter conditions. The old prototype “Magic Box”, now located in the Solar Energy institute at the UPM facilities, was adapted and used to make these tests. As already mentioned in section 3.3, the first problem found was the type of tile material, as rustic stoneware tiles have slightly different dimensions and they are usually furnished with some kind of buckle. On the other hand, rustic stoneware tiles for floor structure are usually of small size. For that reason, the prototype had to be joined together in four pieces, each of 33cm x 33cm x 2cm, into a bigger one 66cm x 66cm x 2cm attached to one container. In this kind of compound systems, it is necessary to adjust the weight of the pieces combined in a bigger format and the thermal energy lost between gaps. It is important to take into account that containers manufactured in the industrialized process use formats that are standardized. This means that adapting irregular pieces with different dimensions is a slow and difficult process, even if easy to handle. The introduction of phase change material substance in the prototype was done in-situ and, as explained above, it had to be done while in its liquid phase. This meant that the PCM had to be transported and handled at a temperature over 38ºC that allowed approximately 4 hours for pouring it in the containers. This would be done during the hours of high solar radiations and carefully so as not to contaminate the substance. Once the prototypes were ready, with the PCM incorporated, the placing and installation of tiles prototypes was easy and fast. Thereafter, sensor equipments were installed to monitor the test room. Interior and exterior temperature data were registered, as well as the temperature of the tiles carrying and not carrying PCM surfaces. With a comparative analysis methodology of these data it was possible to obtain important conclusions about the heat storage that these systems may be able to achieve. The results of the monitoring allowed to conclude that during night hours the system can release heat energy outwards into the environment, reaching a 2ºC difference during peak hours between the PCM tile and the non-PCM, in favour of the PCM system. By contrast, during day hours, when temperature outside is higher and solar radiation increases, the tile system with PCM stores latent heat energy reaching temperature differences of up to 10ºC. In this case, the higher temperature corresponds to the non-PCM system. This particular PCM system is considerably more efficient, as long as tiles are exposed to solar radiation for long periods of time. This is because the system does not depend on the air flow as with previous prototypes. Shadows over the tiles with PCM alter considerably the thermal performance of each piece decreasing their efficiency regarding solar radiation storage.

In 2008, around 20 tile prototypes were developed and built with these characteristics. The main aim was to carry out a thermal study of the

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5. CONCLUSIONS The result of the above experience shows the great efficiency of floor passive conditioning systems with PCM incorporation. The design and selection of materials that form part of these systems depend on their application, specific location in the pavement and the results expected. Raised-technical floors systems are very efficient whenever air flow can be assured going through and triggering the effects of the PCM. The main and greatest advantage of these systems is the pavement’s partial independence from direct solar radiation. Instead, pavements laid over the insulation layer need direct radiation for them to work efficiently. In terms of pavement choice, it is thermally convenient the use of porcelain stoneware, although it is substantially more expensive than rustic stoneware. The pavement format should be selected between medium standard sizes (45cmx60cm, 50cmx50cm, 60cmx60cm) to ensure heat loss decrease with tile’s expansion. In the case of raised-technical floors, the use of metal cylinders to encapsulate PCM instead of a plastic container was an efficient choice. It optimized the air flow between capsules and increased the transfer of heat thanks to a better heat conductivity rate resulting from the material as well as the geometry of the containers used. It is important also to take into account the geometric conditions of the space where the systems will be installed, as PCM’s performance can be affected by deficient and uneven ventilation through the plenum underneath the technical floor. The thermal study of the phase change substance is vital. The material must be of high quality and rely on the supplier’s quality guarantee certificate. This issue is particularly relevant in order to achieve progress and develop PCM incorporation to construction in a safe and efficient manner. Achieving the objective of building in an energy efficient manner requires creating storage and reusing heat systems. The use of PCM incorporation in constructive systems is key to achieve such objective. At this stage, on the basis of the prototypes described above and with the aid of the experience and data obtained so far, it is our intention to develop a proper model for its introduction into the current software available for energy efficiency simulations.

6. ACKNOWLEDGEMENTS A part of the research presented in this paper has been developed in the framework of the INVISO project (Industrialization of Sustainable Housing), subproject 10: Optimization Systems for Efficient Behaviour in Housing, with the financial support of the Spanish Ministry of Science and Innovation. We are grateful to the “Solar Decathlon UPM 2005 Team” for their generous effort and dedication. The first prototype would have never seen the day without their support. The second prototype has been founded by the City Council of Rivas-Vaciamadrid and is presently

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installed and working in the Solar House-Energy Agency Office Building of the city. We wish to thank Gres Rústico Ebro Company for their collaboration and financial support and the department of thermal Analysis in the Chemistry faculty at the Universidad Complutense de Madrid for their help with the PCM substances analysis.

7. REFERENCES [1] E. Caamaño, F.J. Neila, F.J. Jiménez, M.A. Egido, and others. “Viviendas solares autosuficientes: Participación de la Universidad Politécnica de Madrid, en el concurso Solar Decathlon”, Informes de la Construcción Vol. 56 nº. 494, Nov – Dec 2004 [2] FJ Neila, C. Acha, E. Higueras and C. Bedoya, “Los Materiales de Cambio de Fase empleados para la acumulación de energía en la arquitectura. Su aplicación en el prototipo Magic Box”, Materiales de Construcción, Vol. 58, 291, 119 -126, Jul – Sep 2008 [3] J. Queipo, J.M. Navarro, M. Izquierdo, A. del Águila, D. Guinea, M. Villamar, S. Vega and F.J.Neila, “Proyecto de Investigación INVISO: Industrialización de viviendas sostenibles”, Informes de la Construcción, Vol. 61, 513, 73 – 86, jun – mar 2009 [4] A. Pasupathy, R. Velraj, R.V. Seeniraj, “Phase change material-based building architecture for thermal management in residential and commercial establishments”, Renewable and Sustainable Energy Reviews, Vol. 12, 1, 39 – 64, Jan 2008 [5] A. Sharma, V.V. Tyagi, C.R. Chen, and D. Buddhi “Review on thermal energy storage with phase change materials and applications”, Renewable and Sustainable Energy Reviews, Vol. 13, 2, 318 – 345, Feb 2009 [6] Basf, www.basf.com. [7] Rubitherm, www.rubitherm.com [8] E. García, A. de Pablos, M.A. Bengoechea, L. Guaita, M.I. Osendi, P. Miranzo. “Thermal conductivity studies on ceramic floor tiles”. Ceramics International”. 2010. DOI: 10.1016/j.ceramint.2010.09.023 [9] M.C. Hernández-Martínez et al, this conference [10] M.C. Hernández- Martínez, C. Montejo, J. Neila, rd C. Bedoya-Frutos, Proceedings SEEP 2009, 3 International Conference on Sustainable Energy and Environmental Protection, Vol 2, Aug 2009.

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New high-performance insulation materials: Aerogels. Case study: new Munch Museum in Oslo 1

MARIA MEIZOSO and JOSE CARLOS GONZALEZ, Architects 2 Arup, Facades Engineering, Madrid, Spain

ABSTRACT: Aerogels are characterized by high thermal performance and the ability to transmit light associated with daylight comfort. Thanks to the high air content their density is very low and they can be used as an insulation material with very demanding requirements. In previous years, the building sector has been undergoing significant changes in terms of energetic strategies and new sustainable materials. Aerogels are already available on the construction market and they are environmentally sustainable. One of the future requirements will be to keep the sustainable aspects while reducing their cost when they are assembled in a translucent panel. Keywords: high thermal insulation, daylighting, low energy demand, passive strategies, design process.

1. INTRODUCTION Almost all new buildings designed today have something in common; they want to reduce energy demand. This involves developers, designers, contractors and building users alike. All this effort results more and more in high performance and innovative materials and solutions. Low thermal transmittance (U-value) reduces the heat loss in northern climates, as also the heat gain in hot climates, through the façade. This means that the energy used for heating and cooling will be reduced. In order to decrease the thermal transmittance the following measures are normally taken into account:  Increase insulation thickness and use insulation materials with low thermal conductivity.  Reduce the glazed area.  Avoid thermal bridges.  Reduce framing by modifying the layout or by using a different façade system or using large thermal breaks. These measures, usually applied when designing facades with high thermal requirements, can be improved with the integration of “new materials” such as aerogel, a high performance translucent insulation. As the façade is an essential element in creating and maintaining a comfortable environment within the building, in particular in the perimeter area (typically 6 meters from the façade), the application of aerogels in the building envelope provides:  Thermal comfort: surface temperature to be as similar as possible to the internal air temperature.  Visual comfort: avoid glare to excessive light and contrast, provide sufficient daylight levels to perform the tasks required within the building.  Acoustic comfort: reduce noise transmission from outside-inside. Also taking into account the adaptation capacity to future climate change, the traditional parameters with which we design our façades have to be rethought, and greater extremes in terms of heat and cold, wet and dry and noise are to be expected.

The façade thermal performance, especially U and g values, will need to be improved in order to maintain the same internal conditions and levels of comfort. This has further implications for material selection based on their thermal properties. 2.

AEROGELS BRIEF HISTORY

Aerogels sound like something new in the market, like a recent product of modern technology, but the first aerogels were actually developed in 1931 by Steven S. Kistler of the Pacific College in Stockton, California. The name pays tribute to the somehow paradoxical accomplishment of creating a hybrid between a gel and thin air: "Obviously, if one wishes to produce an aerogel, he must replace the liquid with air by some means in which the surface of the liquid is never permitted to recede within the gel. If a liquid is held under pressure always greater than the vapour pressure, and the temperature is raised, it will be transformed at the critical temperature into a gas without two phases having been present at any time." [1] Kistler discovered the secret to drying a gel without collapsing it. He dried his gels at elevated temperatures and pressures, transforming the liquid into a supercritical state wherein there is no longer a distinction between a liquid and a gas. After cranking up the temperature and pressure to create supercritical conditions, pressure is slowly released. The supercritical fluid is vented out of the gel matrix without any surface tension effects. What remains is an aerogel that is more than 96 percent air. After Kistler brought aerogels into the world, they remained a forgotten phenomenon for three decades. Briefly, they re-emerged in scientific literature in the 1960s, but aerogels were not fully resurrected until the 1980s when Arlon Hunt, working for the Lawrence Berkeley National Laboratory, saw their potential.

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3. AEROGEL PROPERTIES

3.2. Thermal properties

3.1. Pore Structure

Aerogels portray a good thermal performance with a reduced thickness in comparison with traditional insulation materials. The passage of thermal energy through an insulating material occurs via three mechanisms: solid conductivity, convection and radiative (infrared) transmission. The sum of these three components gives the total thermal conductivity of the material. Solid conductivity is an intrinsic property of a specific material. For dense silica, solid conductivity is relatively high. However silica aerogels possess a very small (around 10%) fraction of solid silica. Additional solids that are present consist of very small particles linked in a three dimensional network with many "dead ends". Therefore, thermal transport through the solid portion of silica aerogel occurs through a very tortuous path and is not particularly effective. The space not occupied by solids in an aerogel is normally filled with air or another gas unless the material is sealed under a vacuum. These gases can also transport thermal energy through the aerogel. The pores of silica aerogel are open and allow the passage of gas through the material. The mode of thermal transport through silica aerogels involves infrared radiation. Aerogels are reasonably transparent in the infraredwave spectrum (especially between 3-5 microns). At low temperatures though, the radiative component of thermal transport is low, and not a significant problem. At higher temperatures, radiative transport becomes the dominant mode of thermal conduction, and must be dealt with. The total thermal conductivity arising from the sum of these three modes is very low. That’s the reason why there was a renaissance of aerogel technology around 1980, when an increased concern for energy efficiency occurred. The thermal conductivity of silica aerogel is typically 0.018W/mK at 10ºC.

The Silica aerogels have a pore structure difficult to describe because of their different sizes. The International Union of Pure and Applied Chemistry recommends a classification for porous materials where pores of less than 2nm in diameter are termed "micropores", those with diameters between 2 and 50nm are termed "mesopores" and those greater than 50nm in diameter are termed "macropores". Silica aerogels possess pores of all three sizes. However, the majority of the pores fall in the mesopore category, with relatively few micropores. An important aspect of the aerogel pore network is its "open" nature and interconnectedness. Pores in various materials are either open or closed depending on whether the pore walls are solid or porous themselves. A microscopic example of an open-pored material is a common sponge, and "bubble wrap" packaging is an example of a closedpored material. In a closed-pore material, gases or liquids can not enter the pore without breaking the pore walls. This is not the case with an open-pore structure. In this instance, gases or liquids can flow from pore to pore, with limited restriction, and eventually through the entire material. It is this property that makes silica aerogels effective materials for adsorbents, microfiltration membranes and substrates for chemical vapour infiltration.

 

Figure 1: T silica aerogel pore size distribution of a singlestep.

One of the consequences of the pore sizes in aerogels is the level of transparency. Arlon Hunt, from the Lawrence Berkeley National Laboratory, discovered that the largest of the pores was responsible for the scattering and haziness in aerogels. The cross-linked silica particles should be extremely fine, 20-40 angstroms in diameter. That is smaller than the wavelengths of visible light and too small to cause scattering. The average pore size was 200 angstroms in the first aerogels manufacturing process and there were pores of 3,000 angstroms. To make aerogels suitable for use in glazed translucent units, windows or skylights, pores larger than 500 angstroms have to be eliminated. Further research and development is necessary before aerogels are totally transparent.

Figure 2: T silica aerogel thermal conductivity compared with different insulation materials.

3.3. Optical properties As silica aerogels are made of the same material as glass they are called "transparent", but actually they are translucent because of the result of Rayleigh scattering effects. These effects come from the elastic scattering of light by the aerogel pores much smaller than the light wavelength. It occurs when light travels in transparent inhomogeneous solids and liquids but is most prominently seen in gases. Rayleigh scattering is a function of the electric polarizability of the pores.

 

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A simple method can be used to quantitatively measure the relative contributions of Rayleigh scattering and the wavelength independent transmission factor for silica aerogels.

T= transmittance. A= wavelength independent transmission factor. C= intensity of Rayleigh scattering. t= sample thickness. Lambda= wavelength. From this, aerogels with high value of A and low value of C will be the most transparent.

Figure 3: Visible transmission spectrum.

There is then a "visible window" of transmission through silica aerogel that is an attractive feature of this material for daylight applications. 3.4. Physical properties The properties listed below are affected by the conditions used during the manufacturing process and post-processing. Table 1: Aerogel technical characteristics.

Property Apparent density Internal surface area % Solids Mean pore diameter

Value 0.003-0.35 g/cm3 600-1000 m2/g 0.13-15% ~20 nm

Primary particle diameter

2-5 nm

Index of refraction

1.0-1.05

Thermal tolerance Coefficient of thermal expansion Poisson’s ratio

To 500 C 2.0-4.0 x 10-6

Young’s modulus

106-107 N/m2

Tensile strength Fracture toughness Dielectric constant Sound velocity through the medium

But aerogels are expensive and for this reason aerogel applications are limited. Currently the main applications of aerogel are:  Industrial insulation for high temperatures  Building and construction, high performance insulation  Space industries  Equipment manufacturer, trains, airplanes, ships, laptops  Outdoor gear and apparel Since aerogels are translucent and have a low thermal conductivity, they are very good thermal insulators and many studies and evaluations have considered the use of aerogels to insulate various parts of buildings. These applications sometimes appear impractical because of the aerogel assembly high cost. However, more and more the unusual properties of aerogels (good thermal insulation and light transmission) are being required by developers, designers, contractors and building users. The main uses of aerogel insulations commercially available are:  Insulation translucent units: double and triple glazed units, polycarbonate panels, U channel glass, GRP panels, PTFE membrane.  Aerogel blanket with high thermal efficiency and good compression strength.  Thin strips of aerogel applied between wall framing to prevent heat loss through the frame elements. From a life cycle building perspective, aerogels are expensive at the beginning compared with other insulation materials, but their performance helps to save energy considering the building and façade design life.

Figure 4: Thickness comparison chart.

0.2

5. CASE STUDY: NEW MUNCH MUSEUM IN OSLO

16 kPa ~0.8 kPa*m1/2 ~1.1 100 m/sec

4. APPLICATIONS AND INTEGRATION IN BUILDING ENVELOPES: INFLUENCE ON ENERGY PERFORMANCE The production and investigation of aerogels took place during the course of studies devoted to glass.

The design of an envelope in Northern countries, where the climate conditions are very different to the ones most architects are used to, poses challenges that must be carefully addressed taking into account different points in the selection of the façade materials at the earliest stages of design. The façade and cladding of the Munch Museum and the Sternesen Museum Collections in Oslo is an even more compelling task, given the architectural intentions of the building. The design has to find a careful balance between natural light, views, thermal performance, solar control, energy efficiency, buildability and maintenance.

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5.1. Climatic conditions

5.2. Energy saving main goals

The two graphs below summarize the comparison between the annual temperatures of the cities of Oslo (above) and London (below).

The main drivers for the design and engineering of the Munch Museum envelope were:  Reduction of heat transmission. Building programme. Selection of two different spaces: opaque and translucent, and transparent areas, both with low heat transmittance levels. Low thermal conductivity. Each cladding type was analyzed to reduce its thermal conductivity (U-value), by using high performance glass and insulation and reducing the percentage of glazed areas when needed. Very low conductivity values had to be achieved in both glazed and opaque areas. Air tightness. We aimed to reduce air permeability to the bare limits both in the glazed and opaque areas, to reduce heat loss from the inside.  Enhancement of external views and natural lighting. The amount of glazing is higher in the areas where views and natural light is most required: restaurant at the top of the building, offices, main entrance. A specific system was designed in each case to prevent excessive solar radiation (solar control) and heat gain (low U value) Direct external views have been maximized on all floors and elevations in these areas. The use of automatic outer screens allows the combination of sun protection, indirect light and views.  Air humidity and temperature control. To avoid interstitial condensation formation, the vapour control layer will be placed on the warm side of the thermal insulation layer, which, in cold climates, is the inner one. In fact, the internal moisture content in Oslo is very often higher than the external one and therefore it moves from inside to outside due to the vapour pressure difference. Correction of thermal bridges was also important to avoid any risk of surface and interstitial condensation.

Figure 5: Oslo conditions.

Figure 6: London conditions.

The average temperature in Oslo rapidly decreases in winter, reaching average minimum values of -12º C. In summer the temperature remains more stable than in London. The difference between night and day is not as big as in London. In winter, cloud coverage in Oslo is higher and more constant than in London. A psychometric diagram shows that the average humidity is high throughout the year in Oslo, thus condensation in general, and specifically with thermal bridges is an issue to consider during the design.

5.3. Cladding types

Figure 7: Psychometric.

Together with the architects, Herreros Arquitectos, the Arup Façade Engineering project team first identified a number of five main cladding types covering the envelopes and roofs of the building.  Opaque façades, vertical.  Translucent façades.  Transparent façades, vertical.  Transparent façades, inclined.  Opaque horizontal. The aim of this paper is to focus on the translucent areas of the façade where the aerogel is located. This area is around 2,300m2 and the whole façade surface is around 11,000m2. The images below show the elevations where the silica aerogel insulation is located.

Figure 8: Horizontal illuminance July conditions.

As shown above, the horizontal illuminance peak value (due to external sun in July) is 75.000 lux outside. The average horizontal illuminance during the brightest month (July) is 50.000 lux.

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Figure 9: SW and NE elevation of the museum.

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5.4. Building envelope properties

physics:

Thermal

than the value of 0.18W/m2ºK considered by the code for the opaque areas. The U value of the transparent areas is 0.80W/m2ºK, 33% lower than the value of 1.20W/m2ºK considered by the code. The preliminary thermal assessment of the worst façade in thermal terms (West elevation), considering heat losses throughout the year, shows that this façade behaves similarly to an equivalent vertical façade with 20% of openings with the U-values defined by the code. The remaining façades would perform better, since their glazed percentage is smaller.

A qualitative comparison between the museum designed by Herreros Arquitectos and a baseline building was carried out for the more unfavorable elevation, the West façade. The baseline building was designed following the Norwegian code parameters (TEK 2007): • 20% of glazing surface. • U= 0.18 W/m2K for the opaque areas. • U= 1.20 W/m2K for the vision areas. In general terms, the more the façade reduces the heat gain/loss through its envelope, the better the building performs and the lower the energy demands will be. In winter, the heat loss due to the low external temperature through the transparent façade is greater than the heat gain. In Herreros’s project, the west envelope is transparent and translucent: it offsets the heat loss and allows natural light to enter reducing the energy used for electricity. In the baseline building with the properties given by the Norwegian regulation, the heat balance is negative (heat loss is greater than heat gain), even on a sunny day. It can be said that the heating loads in the baseline building are higher than those in the architect’s proposal, so the architect’s proposal performs better in winter. In summer, the heat gain via conduction and convection could be considered negligible. The main heat gain is caused by solar radiation. In the summer scenario, the building designed by Herreros performs slightly worse than the baseline. Nevertheless, since the contribution of longer winter months and less electric lights has not been taken into account, the energy used in the two buildings can be considered as similar throughout the year.

5.5. Daylight conditions A sun path diagram shows the different solar conditions throughout the year at the site. From fall to spring, the sun remains quite low in the sky (see graphs below). It implies that the glazed façade facing North-West seldom receives direct sunlight.

 

Figure 12: Sunpath in December.

Figure 13: Sunpath in March.

On the other hand, the same diagram in JuneJuly shows how the sunset hits the West façade of the Museum, thus creating a situation of heat gains due to irradiation during the evenings.

 

Figure 10: Summer conditions.

Figure 14: Sunpath in June.

Figure 11: Winter conditions.

The design has attempted to follow or improve the Norwegian Code TEK 2007 even in a bespoke volume as our building. Thus: The U-value of the opaque vertical areas was set to 0.10W/m2ºK, 45% lower than the value of 0.18W/m2ºK considered by the code. The U-value of the translucent areas with aerogel is 0.21W/m2ºK in the centre pane, only 17% higher

Figure 15: West sun in June, evenings.

The most critical period was the first half of July where the sunlight can penetrate inside the building. However, in general the low value of solar transmittance of the glazed façade reduces the heat gain through the envelope.

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5.6. Heat gains through the glass: g-value The g-value defines the amount of heat gains that enter the building through its transparent façades. Due to its orientation, heat gains that can be positive for the inner space (in winter) are rather low. The strategy was to gain protection against the inconvenient heat gains in summer, mainly through the west façade, with outer automatic screens. • Transparent façades versus highly insulated façades The percentage of really ‘transparent’ façades is much smaller than the impression one could get with a first glimpse at the building drawings. The reason is that the thermal behaviour of the translucent (insulated) façades is much better than that of a typical window, thus reducing the amount of thermal losses and heat gains. The graph below shows the wider areas that have a 100% transparent glass surface (without translucent insulation). This amounts to around 11% of the net usable space.

The thermal line of this double skin façade is composed by: -

-

10mm clear glass with low emissivity soft coating (ε < 0.04) on surface #2; 16mm Argon filled cavity; 8mm clear glass with low emissivity soft coating (ε < 0.04) on surface #4; 16mm Argon filled cavity; 8mm clear glass; 10mm air filled, sealed cavity; 8mm clear glass; 60mm aerogel; 4.4.2 laminated clear glass.

The following pictures show the geometry of the analysed models of the framing members and the output in terms of temperature distribution and Uvalue of the framing member (UTJ-value) for the typical aerogel areas:

      

 

Figure 17: Middle transom of the aerogel unit -2D model and temperature distribution.

 

Figure 16: Main transparent areas in dash.

• Heat gain control in summer The g-value (% of heat that enters the building through the glass, in relation to the total incident radiation) is rather low in general because of the number of glass layers in the façades: • Translucent façade: g-value < 0.30. • Transparent façade, vertical: g-value < 0.35. • Transparent façade, inclined: g-value < 0.35.

The inclined façade facing West at the top of the tower has the highest radiation in the summer evenings. The solution to control heat radiation during those periods is to deploy an automatic outer Venetian system, connected to the Building Management System.

6. TRANSLUCENT THE FAÇADE

CONFIGURATION

OF

This is the case of 1/3 of North and South orientations of the tower, and also most of the West façade of the tower (except the highest part). The typical solution is a triple glass curtain wall with translucent nanogel insulation glazed panels located at the inner back of the triple glazed unit, an air chamber for maintenance and an external glazed façade (curved glass). The behaviour of this double skin façade during winter is as follows: the external additional curved skin provides improved insulation by increasing the external heat transfer resistance. The reduced air flow and the increased temperature of the air inside the cavity lowers the heat transfer rate on the surface of the glass, which leads to reduction of heat losses. To allow the cavity to help the façades and inner spaces, the joints between the curved glass of the outer façade were closed. During the summer, the warm air inside the cavity had to be extracted by fan supported ventilation.

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Figure 18: Mullion of the aerogel unit - 2D model and temperature distribution.

The centre pane U-value of the above described unit results 0.32 W/m²K. This includes the effect of the joint between two adjacent aerogel panels. Each aerogel double glazed panel is 1m x 2m.

7. SUMMARY OF CONCLUSIONS - Very interesting material for facades applications: high performance thermal insulation, very light, good fire behavior, translucent and able to adapt to future climate change. - Assembling technology available on the market is still in progress and the final costs are very high to be paid by the developers.

8. ACKNOWLEDGEMENTS Thanks to: Jens Richter (Herreros Arquitectos), Arlon Hunt (University of California), Eric Ruiz (Nanogel Cabot), Ignacio Fernández Solla (Arup Façades), Jan Wurm (Arup Materials), and Nicolò Guariento (Arup Building physics).

9. REFERENCES [1] S. S. Kistler, J. Phys. Chem. 34, 52, 1932 [2] Silica Aerogels. Microstructured Materials Group. Lawrence Berkeley National Laboratory, University of Energy. [3] New Munch Museum façades design reports by Arup Facade Engineering. 2010.

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Application of cool materials on solar protection devices to reduce energy consumption and improve thermal comfort conditions in residential buildings Michele ZINZI1, Emiliano CARNIELO2, Stefano AGNOLI3 1

ENEA – Italian national agency for new technologies, energy and the economic sustainable delvelopment, Rome, Italy 2 University of Rome Tre, Rome, Italy 2 University of Rome La Sapienza, Rome, Italy

ABSTRACT: Cooling down buildings and cities is becoming a priority as a consequence of the global increase of air temperatures. This effect determines the increase of the energy consumption for cooling, as well as the spread of the urban heat island. Cool materials are characterised by high solar reflectance and high solar emissivity. These two properties allow the material staying cool under the solar radiation. Cool materials deserved attention during the few past years and they started being used mainly to protect the building roofs. This paper presents the first results of the potential benefit of cool materials applied on solar protection devices in residential buildings. External shutters are often used, especially in the Mediterranean countries, for security reasons and for solar protection during the hot season. These components are generally characterised by high solar absorbance, due to the typical used colours: brown, deep green, grey. An experimental campaign was carried out to measure the reflectance of conventional coloured materials versus cool coloured ones. A double beam spectrophotometer was used for the testing activity. The results were used as input for typical Italian dwellings, changing some parameters according to: Climatic conditions, insulation level, the presence of a cooling system, orientation, the position of the dwelling respect to the whole building. The cooling energy demand was calculated through a dynamic simulation tool. A first assessment on the impact of the technology in the Italian residential buildings is hence carried out. Keywords: cool materials, energy, thermal comfort

1. INTRODUCTION The use of cool materials for building and urban applications is becoming an appealing strategy, especially at some latitudes, because of the increase of the energy consumption for cooling, as well as the increase of the urban heat island effect in large and medium urban area. Both aspects are somehow related to climatic changes and it is expected they will expand the actual magnitude without efficient thermal mitigation techniques at urban and building level. The term cool material refers to a construction material characterised by two main surface properties: a) High solar reflectance ( e), is a measure of the ability of a surface to reflect the incident solar radiation. It is defined as the ratio between the total hemispherical reflectance of a surface (including the specular and diffuse components) and the incident radiation, integrated over the solar spectrum. It is measured on a scale of 0 to 1 (or 0-100%). b) High thermal emissivity ( ), is a measure of the ability of a surface to release the absorbed heat. It is defined as the ratio between the heat flow radiated away be the material surface at a certain temperature and the heat flux radiated by a black body at the same temperature. Infrared emissivity is measured on a scale from 0 to 1 (or 0-100%).

Many examples of vernacular architecture give evidence of how light colours were used to reduce the thermal load in buildings during the hot season. The Mediterranean area still preserves some of the most shining examples. Energy and environmental concerns make this technique interesting again and several studies demonstrated the positive impact in terms of increased thermal comfort and reduced energy loads in buildings and in urban areas [1 to 5]. Most of the study are focused on demonstrating benefits for several applications: residential and industry roofing systems, asphalts for roads and parking lots, coils, PV systems, oil tanks, etc. Another possible application of cool materials is for window shutters. Shutters are widely used in Mediterranean countries as security system for residential buildings, as well as solar protection devices. Traditionally wooden made, they are mainly aluminium based nowadays. One thing remains unchanged through the time, the application of dark colours for a better architectural integration: brown, dark green, red, even black. This solution makes the window coupled with a dark shutter a potential source of overheating during the cooling season. The application of cool materials on solar protection systems was not yet considered, as well as the potential energy savings and the thermal comfort improvement.

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2. PROBLEM APPROACH AND SAMPLE PREPARATION Objective of the study was the assessment of a paint produced with cool pigments applied on aluminium shutters. Cool pigments are very reflective in the near infrared range, while they are transparent in the visible spectrum. The technology allows the material to maintain the original colour, while the reflectance in the solar spectrum is increased. These properties made possible the design of innovative paint based on the same colour of a conventional one, but with an increased solar reflectance. The study was carried out on the usual dark colours, according to the Italian style for shutters. The sample preparation was carried out by an Italian company, which manufactures aluminium products for the building envelope. Two different types of paints were tested: a) Full colours: black, gray and gothic, being the latter a brown colour with small white dots. b) Special design reproducing two typical wood essences (one very dark and one lighter). A standard product and a cool pigment paint were used for each sample type. The first step of the study consisted in the optical characterization of all the selected samples, in order to evaluate the improvement of the solar reflectance with the cool paint application. The next step consisted in moving from the materials properties to the building performances in different Italian climatic zones.

3. OPTICAL MEASUREMENTS The first part of the study concerns the testing of some coatings recently developed through a series of laboratory measurements. The main parameter that characterizes the product from the energy point of view is, as mentioned, the solar reflectance. These spectral measures were performed with a commercial dual-beam spectrophotometer with automatic detection, produced by PerkinElmer: Lambda 950. For the measurements carried out in this experimental study, the instrument is equipped with an integrating sphere, which is necessary for accurate optical measurements of samples with a non-specular and generically diffusing behaviour. The scan range is set between 300 and 2500 nanometres and the scan is performed at every nanometre. The width of the slit is two nanometres in the visible spectrum and 20 nanometres in the near infrared spectrum. The scanning speed is about 50 nm/min. Figures 1, 2 and 3 show the comparison between the spectral trend of a conventional coating for aluminium shutters and the same material treated with cool pigments and characterised by a high reflectance. Measurements were performed on the black, gray and gothic samples. The solar integrated values of the measured curves were calculated applying the international relevant standards: ISO 9050:2003 and EN 410:1998 procedures. The results of the solar ( e) and luminous reflectance ( v), together with colour rendering index Ra are presented in Table 1.

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The difference in solar reflectance is evident in all cases, increasing between 3 and 4 times for cool coatings respect to the standard materials. The difference is even greater in the near infrared spectrum: in this case the reflectance of the cool materials increases between 6 (gothic) and 10 (black) times compared to conventional materials. Black coating reflectance [%]

80 Cool

70

Standard 60 50 40 30 20 10 0 300

500

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1300

1500

1700

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wavelength

Figure 1: Comparison between a cool and a standard black coating Gray coating reflectance [%]

80 70

Cool Standard

60 50 40 30 20 10 0 300

500

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1300 1500 wavelength

1700

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Figure 2: Comparison between a cool and a standard gray coating Gothic coating reflectance [%]

80 70

Cool Standard

60 50 40 30 20 10 0 300

500

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1300 1500 wavelength

1700

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2300

2500

Figure 3: Comparison between a cool and a standard gothic coating

The chromatic comparison between cool and standard coatings is very similar for black and gray and, in fact, the reflectance in the visible spectrum changes for values of less than 2 per thousand. The discrepancy increases in the case of gothic colour, with a difference on the integrated visible spectrum of about 1% in favour of conventional paint. This difference can be seen observing the two spectral curves in the visible region (380-780 nanometres) in Figure 3.

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Table 1: Solar reflectance (ρe), luminous reflectance (ρv) and colour rendering (Ra) of the following materials: black, gray and gothic.

Blac. Blac. Gray Cool Cool ρe ISO 20.9 4.8 23.3 ρv ISO 5.0 4.8 8.0 ρe EN 20.2 4.8 22.6 ρv EN 5.0 4.8 8.0 Ra 95.1 99.5 94.2

Gray 6.9 7.9 7.0 7.9 94.9

Goth. Goth. Cool 23.6 7.9 7.0 8.0 22.9 7.8 7.0 8.0 88.4 88.0

Dark brown coating reflectance [%] 80 Cool

70

Standard 60 50 40 30 20 10 0 300

500

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1300 1500 wavelength

1700

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Figure 4: Comparison between a cool and a conventional dark brown background for wood-alike treatment Light brown coating reflectance [%] 80 Cool

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Standard 60 50 40 30 20 10 0 300

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Figure 5: Comparison between a cool and a conventional light brown background for wood-alike treatment Wood-alike coating reflectance [%] 80

4. NUMERICAL ANALYSIS

Test 1 Test 2 Tets 3

70 60 50 40 30 20 10 0 300

500

700

discrepancies. The solar reflectance increased from about 26 to 36% for the dark brown and from 30% to about 36% for the light brown. The chromatic response is slightly different, as it can be inferred by the curves of Figures 4 and 5 in the visible band, between 380 and 780 nanometres. Both the conventional materials increase their reflectance in the infrared. Analyzing these results, the light brown has more potentialities and should be evaluated on the basis of samples that have a more similar response in the visible spectrum. The last set of measures has been dedicated to materials made of aluminium with a wood-alike colour, using as background the two colours previously tested. As expected, the results are in line with those obtained for the background. The effect of reflective paint increases the reflectance from 25.9% to 31.7% for the essence of dark brown wood and from 28.2% to 33.7% for the essence of light brown wood. However, one interesting fact concerns the accuracy of the measure in this testing: the wood-like colours are characterized by textures, which present different chromatic gradations of the wood. For this reason, three tests were performed on each sample by analyzing grain with different gradations, see Figure 6. The near-infrared spectra are practically coincident, while the results change depending on the point of investigation in the visible spectrum. A final notation, common to all tested materials, concerns the near-infrared reflective pigments. These materials give to the product high reflectance levels after 1600 nanometres. Whereas the visible spectrum ends before the 800 nanometres there is a wide portion of the spectrum (800-1600 nanometres) in which the reflectance of the product could be improved, with an average contribution over the entire solar spectrum estimated around 5-8%. The reflectance drops again in the periphery of the infrared spectrum (after 2000 nanometres), but the energy content of solar radiation at these wavelengths is so modest that it’s not necessary to suggest actions to optimise the spectral response of the product.

900

1100

1300

1500

1700

1900

2100

2300

2500

wavelength

Figure 6: Spectral trend of three tests carried on a woodalike cool colour painted on a dark brown background

The second set of samples was carried out on two brown paints. Two different types of brown were tested, one light and one dark, which have the function of background in the industrial process for the production of wood-alike colours. The comparison between conventional paints and cool coloured materials shows significant

The second part of the study is dedicated to assessing the impact of these products in dwellings, building category suitable for shutters applications. Energy performances of envelope components are a function of several variables. The building geometry is one of the most important. This study is focused on a detached single floor house, which represents a noticeable portion of the Italian dwelling stock. Cool shutters are, moreover, developed for seasonal dwellings, typically used in summertime when the cooling demand of cooled buildings and overheating are an important issue. Different building size, shape and geometry lead to different results. What follows is an example of the technology potentialities. Two main building uses were defined: Calculation of the net energy for a cooled building. Energy systems efficiencies were not

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considered since the aim was comparing different envelope configurations. Calculation of the thermal comfort conditions in a not cooled building. The assessment was carried out in terms of discomfort hours during the cooling season as a function of the operative temperature. The impact of the product was evaluated by comparing the results obtained for each configuration with cool or conventional paint for shutters. The calculations were performed using the Design Builder interface that supports the EnergyPlus Calculation Engine, a model based on hourly analysis of the building thermal behaviour. 4.1. Climatic zones Three areas of interest were individuated at national level: Palermo, for southern Italy; Rome for the centre of Italy and Venice for northern Italy. These localities were selected for several reasons. They identify very populated areas of the country, where shutters are widely used in new and existing buildings. Moreover their regions are characterised by a significant seasonal building stock. Palermo has the most severe summer conditions both in terms of air temperature and solar radiation levels. Rome and Venice have a similar climatic severity, even if with a different mix of air temperature and solar radiation levels.

scheme in Figure 7 right. Persiana is made of horizontal lamellae fixed on a wide sash. The lamellae are steeply tilted, so that only minor solar radiation reflected by the ground outside diffusely enters into the building. Scuretto is a moveable thick shutter, which completely covers the window surface, typical of several areas in the north of Italy, see figure 7 left. They are considered equivalent in this study because both allow high natural ventilation reducing direct solar gains, while allow secondary heat transfer due to the absorbed and re-emitted long wave radiation. A section of the components is presented in Figure 7. Table 2: Thermal properties of the building envelope.

Envelope component Wall Roof Base floor Window

U not ins. [W/m2] 1.57 1.52 1.57 4.70

U Palermo [W/m2] 0.48 0.45 0.55 1.95

U Rome [W/m2] 0.36 0.37 0.41 1.95

U Venice [W/m2] 0.39 0.35 0.38 1.95

4.2. The reference building The test building implemented for the study is a simple one level detached house with flat roof and base floor placed directly on the ground. The detached house represents a consistent portion of the national buildings stock, since almost the half of the existing residential buildings consists of single or bi-familiar houses. The net area of the building is 2 3 99.5 m and the net volume is 308 m , measures representative of the average Italian dwellings. 2 The global windows surface is 15 m divided in: 2 2 4.5 m on the south and west facade, 3.2 m on the east and north façade. These values are in line with national standards and typical design criteria. Simulations were performed on two envelope configurations: insulated and not insulated, condition representative of most of existing buildings. Only one common value of thermal transmittance was considered for the not insulated building in the three climatic zones, while values according to Italian Standard Reference were taken for the insulated configuration. Thermal transmittance values are summarised in Table 2. The same window was implemented in the three zones for uniformity comparison. The selected windows, whose thermal transmittance values are reported in Table 2, are: Not insulated window: single glass with wooden frame, a typical configuration for aged buildings. Insulated window: a low transmittance double glazing unit (4-16-4) with wooden frame. Each window is equipped with Italian typical shutters. Persiana is a moveable shutter widely used in Lazio and in many areas of southern Italy, as well as in several southern European countries, see

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Figure 7:Cross section of a window protected by a Scuretto, left, and Persiana..

As the study involves the optimization of building performance during summer, it is assumed that the shutters will always remain closed during the day in order to minimise the solar gains. Two values of solar reflectance referring to the back materials were considered: 4.8% and 20.9%, respectively for conventional and high reflectance materials. In the case of not-cooled building, it is assumed that the window is always open during the 24 hours, with sunscreen always closed, at least during the day. An air exchange of 3 ACH is estimated for this configuration. Even if this is not the optimal passive strategy, this is what happen in practice in Italian and south European countries. In the case of cooled building, it is estimated a cooling systems use of 12 hours, from 9.00 am to 9.00 pm. The power of cooling system is considered unlimited to ensure the comfort conditions (air temperature 26 °C) whatever external conditions. During the night, the system is switched off and the temperature is in free floating conditions. The air exchanges were set at 0.3 ACH when cooling system is on and 3 ACH when the cooling system is switched off.

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Because of the constructive features of the shutters, the direct solar gain is not so important, while the secondary one is significant because it represents the portion of solar radiation absorbed by the element opaque and subsequently radiated to the indoor environment. In both cases, the internal gains due to the presence of people, artificial lighting and household 2 appliances were set as follows: 5.6 W/m during the 2 period of energy systems use and 2.8 W/m during the rest of the time (night time). These values were selected according to the national standards, which set the reference internal gains as a function of the room/building size.

the thermal zone, as well as the surface temperatures, including the shutter temperature. The th reference cooling period is from May 15 until th September 15 . Not insulated house - net cooling demand [kWh]

1000 900 800

standard shutters

700

cool shutters

600 500 400 300 200 100

5. RESULTS

0

The results are grouped according to the two building uses: with and without cooling systems. The net cooling demand is considered as main indicator for the former, operative temperature profiles for the latter.

Palermo

Rome

Venice

Figure 8: Net cooling demand for the not-insulated house configuration equipped with conventional and cool shutters in Palermo, Rome and Venice Insulated house - net cooling demand [kWh] 700

5.1. Cooled building

650

The results are summarised in Figure 8 and 9 for the insulated and not insulated configurations. The cooling loads are, as expected, higher in the not insulated building and the cool shutters have a positive impact on the energy demand. The cooling demand decreases of 38 kWh per year in Palermo (from 929 to 892 kWh), while reductions between 15 and 17 kilowatt-hours were obtained for Rome and Venice, characterized by smaller energy demands, respectively 258 and 320 kWh. The relative energy savings respects to the initial performances are: 4.1% in Palermo, 5.8% in Rome and 5.3% in Venice. To be noted that the smallest relative saving is the best absolute saving, because of the most severe summer climatic conditions in Palermo, Sicily. The upgrade of the building envelope performance with insulated components has the result of reducing the cooling energy demand and, as a consequence, the absolute energy savings. The cooling demand decreases of 20 kWh per year in Palermo (from 585 to 565 kWh), while reductions between 8 and 9 kilowatt-hours are calculated for Rome and Venice, whose cooling demands drops respectively to 105 and 162 kWh. The relative energy savings are: 3.2% in Palermo, 7.1% in Rome and 5.3% in Venice. The results show that cool shutters improve the cooling performances of this single family house but the overall impact is limited, because of the small amount of fenestration surfaces in residential buildings. Another issue is the impact of the glazing and frame thermal resistance to the secondary solar heat transfer due to the shutters solar absorption. 5.2. Not cooled building The impact of cool shutters is here more evident than in the cooled building, being the sun-heated shutters in direct contact with the indoor environment. The selected performance indicator used for the analysis is the operative temperature (to), which takes into account the air temperature of

600 550

standard shutters

500

cool shutters

450 400 350 300 250 200 150 100 50 0

Palermo

Rome

Venice

Figure 9: Net cooling demand for the insulated house configuration equipped with conventional and cool shutters in Palermo, Rome and Venice

The situation is a function according to the climate severity: 26 °C are reached in the 57% of the period in Palermo and about the 23% of the period in Rome and Venice for the not insulated building. Operative temperatures higher than 28 °C are reached in Palermo in the 25% of the period, while in Rome and Venice in less than the 10%. The cumulative distribution shows that the number of hours with operative temperature higher than 26 °C is reduced by 6.6% as an average for the three localities for the not insulated building when using the cool shutters. The value increases up to 20% for the 28 °C threshold and to 33% for temperature above 30 °C. The results are summarised in Table 3. Trends are similar for the insulated building configuration, even if the intensities change. The results are summarised in Table 3. There is a general shift, but limited to few percent units, towards higher thermal levels in terms of hours above the fixed threshold. The cumulative distribution shows that the number of hours with operative temperature higher than 26 °C is reduced by 9.6% as an average for the three localities. The value increases up to 29% for the 28 °C threshold, with a maximum in Rome with a reduction corresponding to the 43% of the hours. There is a strong reduction of hours above 30 °C in Palermo and Venice, respectively 56% and 31%.

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Table 3: Cumulative distribution (number of hours and percentage to the period) of indoor operative temperatures above 26, 28 and 30°C for standard and cool shutters. Hours and percentage reduction are also indicated. Not- insulated building

to [°C]

St. shutters [h]

St. shutters [%]

>26 >28 >30

1707 746 130

57.4 25.1 4.4

>26 >28 >30

761 128 0

25.6 4.3 0.0

>26 >28 >30

740 246 40

24.9 8.3 1.3

>26 >28 >30

1953 1006 175

65.6 33.8 5.9

>26 >28 >30

1044 236 0

35.1 7.9 0.0

>26 >28 >30

948 320 45

31.9 10.8 1.5

Cool shutters Cool shutters [h] [%] Palermo – Not insulated 1630 54.8 651 21.9 85 2.9 Rome – Not insulated 695 23.4 93 3.1 0 0.0 Venice – Not insulated 690 23.2 203 6.8 27 0.9 Palermo – Insulated 1864 62.6 858 28.8 86 2.9 Rome – Insulated 904 30.4 137 4.6 0 0.0 Venice – Insulated 846 28.4 235 7.9 31 1.0

6. CONCLUSIONS The study demonstrates that cool materials can be used for shutters and solar protection devices, increasing the solar reflectance values without penalizing chromatic solutions, typical of the Italian architectural tradition. The optical measurement campaign shows that significant results can be achieved on some products, while more improvements are needed for the wood-alike essences. It is also important noting that, according to the spectral curves, it is possible optimizing the effectiveness of the cool paint since the visible range ends at 800 nanometres, but the developed coating reaches the maximum at 1600 nanometres. A calibrated increase of the spectral reflectance at lower wavelength, typically immediately after the visible range, may increase the solar reflectance of several percentage points. The calculation performed on the reference building demonstrated the positive impact of more reflective envelope components, even if the overall savings are affected by several geometric and thermo-physical limitations. Net cooling energy savings vary between 3.2% and 7.1%. Analyses that take in account the entire year (heating + cooling) are needed for continuously used dwellings. Cool materials are most effectively in reducing extreme indoor operative temperatures, as demonstrated by the reduction of hours with more than 28 and 30 °C. To be noted that even if colder in winter, Venice shows higher cooling demand; this

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Reduction [h]

Reduction [%]

77 95 45

4.5 12.7 34.6

66 35 0

8.7 27.3 ---

50 43 13

6.8 17.5 32.5

89 148 89

4.7 16.3 56.4

140 99 0

13.3 43.3 ---

102 85 14

10.8 26.6 31.1

implies the importance of active and/or passive cooling solutions even in the north Italian area.

7. REFERENCES [1] Akbari, H., Bretz, S., Kurn, D., Hartford, H., 1997. Peak power and cooling energy savings of high albedo roofs. Energy and Buildings 25 (1997) 117 –126. [2] Akbari, H., Levinson, R., Rainer, L., 2005. Monitoring the energy-use effects of cool roofs on California commercial buildings. Energy and Buildings 37 (2005) 1007–1016 [3] Synnefa, A., Santamouris, M., Akbari, H. (2007), ‘Estimating the effect of using cool coatings on energy loads and thermal comfort in residential buildings in various climatic conditions’, Energy and Buildings, vol. 39 (11), pp 1167-1174 [4] Synnefa, A., Santamouris, M., Apostolakis, K. (2007) ‘On the development, optical properties and thermal performance of cool colored coatings for the urban environment’, Solar Energy, vol. 81, pp 488–497 [5] Zinzi, M., & Fasano, G. (2009), ‘Properties and performance of advanced reflective paints to reduce the cooling loads in buildings and mitigate the heat island effect in urban areas’, International Journal of Sustainable Energy vol. 28 (1), pp 123-139.

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The Future Life Cycle of Intelligent Facades Dr Craig Lee MARTIN & Craig STOTT 1 1

Manchester School of Architecture, United Kingdom

ABSTRACT: The UK building industry accounts for approximately 50% of the nation's total energy consumption; generating 33% of landfill waste [1]. Reducing both is paramount for a sustainable future. Disproportionate amounts of energy are currently expended maintaining comfortable internal climates. Intelligent Façades can play a significant role in reducing this energy demand. Intelligent Façades can also be designed to eliminate their construction waste through considering their future Lifecycle. In ‘Cradle-to-Cradle’ McDonough and Braungart [2] develop James Lovelock’s Gaia [3] principles of sustaining existence through closed loop systems with their eco-effective approach to product design. Modelled on natural processes, Eco-Effective design offers a paradigm shift away from the ‘be less bad’ eco-efficient, by promoting ‘waste as food’. Upcycling is the remanufacturing of nutrients, which have fulfilled their primary use, into higher value environmental products. On this premise future Intelligent Façades should be fully upcyclable. At the end of their designed life all components should be efficiently removed and returned to a manufacturer to be reused without wastage. Working alongside façade manufacturer Lindner, architects and Zurich ETH Professors Gramazio & Kohler, and architects 3XN, enabled this research to fully explore the possibilities of an eco-effective design ethos, and devise a set of proposals that could facilitate a global reduction in carbon emissions. Through interpreting and implementing a closed-loop strategy, this paper extends the knowledge of Intelligent Façades day-to-day operation by exploring their future life cycle and eco-effectiveness; i.e. the potential modes of decommissioning and upcycling. Keywords: Eco-Effective, Life Cycle, Façade, Upcycling, Cradle-to-Cradle

1. INTRODUCTION ‘Can future Intelligent Façades be designed to encompass their entire life cycle; from inception and materials through to decommission and upcycling?’ To answer this, three areas were considered: ¥ The importance of the living planet Gaia and how biomimicing natural life cycles is critical for establishing an eco-effective design strategy. ¥ The relevance of Intelligent Façades and the role they have to play in rescuing Gaia. ¥ The current state of sustainable design. The research was conducted in collaboration with façade manufacturer Lindner, who discussed the most prevalent issues and provided a series of case studies to outline the current failings of contemporary design, and architects Gramazio & Kohler in Zurich and 3XN in Copenhagen who specialise in advanced renewable technologies and digital design. The aim was to pinpoint the key areas currently obstructing wide-scale adoption of sustainable development in the area of façade design and to suggest appropriate strategies for change.

atmosphere, resulting in homeostatic feedback causing runaway global warming.

positive

2.2. Eco-Effective An attempt to counter the destructive tendencies of man was proposed by Michael Braungart and William McDonough in their 2002 text ‘Cradle to Cradle’. It offers a paradigm shift away from the ‘be less bad’ eco-efficient, by promoting an Eco-Effective design strategy where ‘waste equals food’. EcoEffective design models human industry on natural processes through its biomimetic approach to the design of systems. The ideology suggests that all items we make, use and discard, eventually provide nutrition for Industry and Nature alike come the end of their working life. The aspiration is a world in which all human activity nourishes rather than destroys, leaving behind a delightful restorative footprint as opposed to today’s degenerative one. In this philosophy human growth is actually viewed positively; the greater the consumption, the higher the abundance of nutrients. 2.3. Contemporary Architectural Barriers

2. CRADLE TO CRADLE: THE LIFEHALT 2.1. The Importance of Lifecycle James Lovelock proposed the Gaia hypothesis in the early 1970’s, suggesting the earth in its entirety ‘lives’ as a single complex entity forming an intricate interacting system. That system maintains the Earth in an ideal homeostasis for life to flourish. In return, life itself acts as a regulator through actions and evolution. The lack of respect shown Gaia by humanity has disabled her capacity to manage the effects of additional greenhouse gases in the

At first glance the notion of increased human consumption appears heretic to those of the established sustainable doctrine, however if the theory is applied it results in a biomimetic design approach that transforms the manufacture and consumption of goods into a regenerative force. Contemporary lifestyles in the developed world are incredibly wasteful, with many usable or edible products being ‘Lifehalted’ in landfill. In 2009 the UK produced 434million tonnes of waste. 73% of this went to landfill, even though 90% was recoverable and could have be recycled, composted or used to generate energy (This figure must be cut by over two

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thirds to meet the EU 2020 target). The construction industry contributes a significant proportion of this waste. Hence an eco-effective design strategy for Intelligent Façades is vitally important. One architectural component where environmental improvements could be sought is the building skin. Contemporary façades from brick built dwellings to high-rise glazed towers offer little more than a barrier between inside and out. This primary function has barely evolved in millennia. The vast majority of buildings still require; heating and/or cooling; a national grid delivering power; materials with high ecological footprints that cannot be reused after demolition. A comprehensive Intelligent Façade design would address these issues and many more.

3. LIFECYCLE: THE DESIGN PARADIGM 3.1. Intelligent Façade Typologies Despite the many guises of Intelligent Façade, they fall rather comprehensively into three categories; Insolar Façade, Taxonometric Façade, and Responsive Façade. These are defined by the inherent ‘intelligence’ and what the design is attempting to achieve. The definitions build on one another, meaning one configuration can belong to all three categories, and ideally will do. An Insolar Façade is a scheme based upon the principles of solar analysis. It is configured in such a way as to minimise or maximise the effects of insolation as required by the building typology. Taxonometric Façades are those created from a standard kit of parts. The design should allow for many configurations, meaning each scheme using the system can display an individual appearance. The key to the Taxonometric approach is the ability to design for decommission. As the componentry is devised to attach together in a certain sequence, that sequence can be reversed, enabling the façade to be safely and efficiently dismantled. The elements can subsequently be returned to the manufacturer for reuse in another project, or Upcycled to comply with a newer design revision. Lindner’s ECO Fassade (Fig.1) has been designed to achieve these criterion. Lindner commissioned PE International to conduct a full Lifecycle analysis upon the ECO Fassade, the details of which are discussed in Section 3.2.

Figure 1: Lindner’s Taxonometric Façade

Responsive façades are those that display autonomous control. They exhibit an ability to comprehend and learn from their surroundings, adjusting behaviour accordingly. The building skin is not inert, but transforms dynamically to regulate the

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internal environment, reducing its power demands. Ideally they include methods for generating energy. 3.2. Life Cycle Assessment A Life Cycle Assessment (LCA) is a study and appraisal of the environmental effects for any given product. It considers the extraction and creation of raw material, transportation, manufacture, construction, decommissioning, and recycling or waste creation. Extras such as auxiliary material, packaging, water consumption, amount of recycled content, waste treatment, and even radioactive waste should the energy come from a nuclear power station are also included. LCA’s don't however take into account the usage or efficiency of the item being evaluated, hence for this report the functional properties of the façade are not incorporated. PE International developed the LCA software GaBi4. The outcomes are classified into energy and water consumption, waste, and six potential impact categories: global warming, ozone depletion, abiotic, summer smog, acidification, and eutrophication. Whilst incredibly useful the process is complicated, thus the final figures contain large tolerances. At their behest, PE International analysed Lindner’s new Eco Fassade using GaBi4. The results are interesting and summarised below, however they lack context as no others exist for a building façade system. The total energy consumed in the manufacture and production phase of three standard elemental façade types: 2 ¥ Fully Glazed = 2,480 MJ/m 2 ¥ Fully Clad = 1,950 MJ/m 2 ¥ Part Clad = 3,270 MJ/m The total energy consumed for the façade's remaining Lifecycle, (transportation, on-site construction, and decommissioning), up to the point where the elements are either recycled or discarded: 2 ¥ Fully Glazed = 1,340 MJ/m 2 ¥ Fully Clad = 1,300 MJ/m 2 ¥ Part Clad = 1,840 MJ/m The Part Glazed configuration consumes the greatest amount of energy due to the increased number of elements. Transport contributes less than 1% of the total, with the average material distance travelled being just 415km. The configuration also comes last in five of the six impact categories, with Fully Clad proving best in five out of the six. Overall, the LCA concluded that two aspects caused the greatest environmental damage: ¥ Preparation of the anodized aluminium profiles, due to the amount of water and heat required. ¥ Preparation of the aluminium and steel cladding in the Part Clad and Fully Clad variants. Whilst initially surprising that the Fully Glazed configuration does not pose the greatest primary threat, construction glass has a series of inherent problems regarding its possible future reuse and Upcycling, discussed further in Section 4.4. The LCA report states that when Fully Glazed, the Greenhouse Potential is increased by 25% due to the need for insulated glazing. With a reduction in CO2 emissions critical in the fight against global climate change, it could be argued that this is actually the greatest environmental threat. This

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reasoning is further strengthened when embodied energies and power sources are considered. The LCA report also states the Lindner Eco Fassade system is almost 100% recyclable, depending upon the use of a mechanical form of captive glazing gasket. Mechanical capture results in larger mullions, which consumes more aluminium. However, an adhesively glazed system of noncaptive glass fixed with Ethylene Propylene Diene Monomer (EPDM) is not at all recyclable due to the inability to separate the glass from the EPDM. Hence, any design decisions must take into account the future reusability of the materials. To add some perspective to the emission findings, Lindner calculated a comparison. An average car produces 165g CO2/km, hence if driven for a typical annual amount of 10,000km it releases 1,650kg CO2. A typical city office façade can be estimated to cover 25storeys of a 25m x 25m floor 2 plan, equalling 10,000m . Assuming a fairly low 2 figure based upon the LCA findings of 100kg CO2/m the façade manufacture emits a substantial 1,000,000kg CO2. When considered in such a manner, the importance of the subject matter becomes exceptionally pertinent. Gaining an understanding of these issues and defining methods for reduction is key to developing a successful Eco-Effective design, and why the LCA is an incredibly useful exercise.

4. CONTEMPORARY ARCHITECTURE VS UPCYCLING: INVESTIGATIONS An Eco-Effective approach offers a solution to the construction industry’s waste issues. It would create a true closed loop society where waste was no longer a negative aspect, but a source of nutrients waste equals food. Lindner conducted two studies in addition to the LCA looking into ways of minimising their ecological footprint. 4.1. Case Study - Harlequin 1 Investigation 1 considered the average recycled content for new material. It came as a response to a query raised by a client. BSkyB, with architects Arup Associates, wanted to design and build Europe's most sustainable broadcasting venue. The aim was for Harlequin 1 in Brentford to achieve BREEAM Excellent and a 35% reduction in carbon footprint when compared to the previous incarnation. To attain this BSkyB insisted on a plethora of energy saving measures including natural ventilation, wind turbines, a biomass fuelled CHP and rainwater harvesting. Lindner were contracted to provide an Insolar façade system. BSkyB prescribed the percentage of recycled content they desired the façade materials to contain, detailed in Table 1: Table 1: BSkyB’s Recycled Material Content Specification for Harlequin 1 Material (external Façades) Aluminium - Extrusion Aluminium - Sheet Glass Pre-Cast Concrete Steel

Recycled Content (by mass) 44% 73% 10 - 20% 45% 25 - 90%

Lindner approached the request by determining the greatest percentage of recycled material that could be included for high quality products. Table 2 shows the six most common materials and their average recycled content. The values represent normal, good quality, commercially available products with a recycled content appropriate to the creation of high quality Intelligent Façades. Table 2: Lindners Recycled Material Content Material (external Façades) Aluminium - Extrusion Aluminium - Sheet Glass Steel Insulation Gaskets, Silicone & EPDM

Recycled Content (by mass) Not more than 22% Normally 22% 12 - 95% 30% Unknown 70% Nil

BSkyB accepted Lindner’s findings following an indepth discussion and analysis of possible methods to increase the percentages. Whilst not being able to do so is disappointing, the fact large corporations and architects such as BSkyB and Arup Associates are beginning to seriously consider these aspects bodes well for future improvements and the eventual adoption of an Eco-Effective design strategy. An investigation into the future recyclability of Lindner products, conducted in the UK office under the leadership of Technical Director John Libby placed the onus firmly with architects. Libby suggests “designers must gain a fundamental understanding of the manufacturing process and the ecological implications of their design decisions”. Two material examples are discussed below, to illustrate Lindner's position. 4.2. Aluminium Alloys complicate the upcycling of aluminium. When specifying products it is vitally important architects consult their manufacturer, engineer and supplier to determine which alloy most appropriate for the job has the smallest environmental impact. The chosen finishes and coatings applied are equally significant. A standard anodised finish using simple oxidisation is the best option, for it leaves the product fully Upcyclable. Powder coating aluminium involves the use of a polymer such as polyurethane being baked onto the outer surface. This is recyclable but requires the use of a suspected human carcinogen methylene chloride, or energy intensive abrasive blasting, both of which damage the underlying aluminium, causing impurities. Finally, there are numerous 'non-standard' coatings such as high silicon for specific conditions such as corrosive environments. Many of these render the aluminium completely unusable for future reuse, as such the appropriateness of specifying aluminium in these circumstances must be questioned. 4.3. Glass Glass recycling is widespread and very efficient. Unfortunately, not all glass is the same, and certain architectural glass is difficult to Upcycle. Advancements are continually being made; for

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example, it is now possible to specify PVC-U windows that can be disassembled at the end of their working lives. The glass is recycled into cullet, the aluminium tracks and beadings can be re-used or Upcycled and the PVC-U frames can be processed into micronised powder ready for a new moulding. Glazing suffers from attempting to achieve two conflicting goals. Its primary function is to allow natural light in and afford a view out, accompanied by facilitating solar gain. However juxtaposing these aims are minimising glare, heat loss and excessive solar gain. Regrettably, most currently popular solutions have grave environmental implications for future upcycling. Low emissivity (Low-E) coatings are one such case in point. When applied to glass they reflect radiant infrared radiation, hence keeping heat energy on the exterior whilst allowing light in the visible spectrum to pass through. Low-E coatings work wonderfully well at minimising excessive solar heat gains, but have proven extremely problematic for Upcycling. The coatings are usually metallic; titanium, zinc, chromium, silver, tin or even gold, and are applied as a ‘hardcoat’ during the annealing phase of the float glass process. Once administered the coatings cannot be removed, even under extreme temperatures. Consequently any future product created using cullet from Low-E coated glazing, literally falls apart as the metallic elements will not bond. Hence Low-E coating regulate overheating, yet prohibit any future usage of the material.

One area requiring a drastic rethink is floor to ceiling glazing. In Britain, any glass located below 800mm from floor height must be laminated safety glass. This is most commonly formed by sandwiching a clear pane of Polyvinyl Butyral Plastic (PVB) between two panes of glass under mild heat and pressure. The glass adheres to the PVB so actively that it does not shatter, remaining intact when broken. PVB is an expensive high performance thermoplastic polymer; its necessity vastly increases glazing costs. PVB itself is fully Upcyclable, however to separate the bonded lamination is such an energy and labour intensive activity it is not economically viable, hence scrapped safety glass heads for landfill. This type of Lifehalt must be addressed in order to reduce the carbon footprint. Simple design choices can instantaneously minimise the issue. One possible solution for areas where safety glass is required could be the use of biological adhesives. If the glass and shatter proof layer, not necessarily PVB, were bonded in this manner, a biological solvent could harmlessly split the two come the end of their working life. The technology to achieve such a product exists, but is not pursued due to economic constraints. It is areas like these, requiring high capital expenditure but offering longterm financial and ecological incentives, where government funded research should be focused. 4.5. PFI Building Systems

4.4. Case Study – Microshade With an eco-effective mentality Low-E coatings would simply not be accepted due to their deficiencies for future Upcycling, alternatives would be sought and developed. In this case a solution has been engineered by Danish firm MicroShade in conjunction with architects 3XN, (Fig.2). A micro perforated stainless steel lamella strip, just 200µm thick is mechanically fixed within standard double or triple glazed units, meaning it is fully recyclable. The micro-perforations are angled to emit a higher percentage of low-level light, whilst reducing highangle sun penetration by 90%. It can be configured either to appear unnoticeable to the viewer, or to include a patternation. The concept is so successful that Low-E coatings and external solar shading devices are no longer required, resulting in greatly reduced material consumption and economic costs. MicroShade is a good example of an eco-effective product, designed to mitigate an ecological problem whilst not contributing to one. 



 Figure 2: Microshade.

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The UK and Australian governments originally developed Private Finance Initiatives (PFI’s) as a means of funding public projects with private capital. In its basic form a PFI can be viewed as a means of reallocating ownership for the functional benefit of those relinquishing control, and long-term financial gain of the recipient. In architecture this could be employed for ecological gains as well. The concept involves the manufacturers of building materials and services not relinquishing responsibility for their product, but effectively leasing them to the client for a contractually agreed lifespan. Throughout a buildings working life the manufacturer maintains and cares for their products, come the end of that life it is the manufacturer’s duty to decommission their property and remove it. The scheme enables new agreements to be formed - either extending the existing contract, or facilitating an upgrade. A PFI Building Systems initiative (PFIBS) makes commercial and ecological sense. The maintenance provided by manufacturers throughout a products working life ensures a product remains in excellent working condition, reducing building running costs for the client and ensuring building occupiers are never dissatisfied. As the manufacturer is contractually required to repossess the products at a future date, design for decommissions and upcycling becomes an integral part. Consequently wastage and raw material consumption would both significantly decrease. Naturally the concept is not without its detractors who question the realistic possibilities mainly due to the high level of litigation necessary. There are other hurdles that require overcoming before PFIBS’s become a realisable prospect. However, the potential advancements of such an

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initiative are consideration.

significant

and

warrant

further

5. INTELLIGENT FAÇADE FUTURES: THE REALISATION

professionals, yet as stated by Brian Anson in 1979, “The Architect who isn't a philanthropist is a philistine” [6]. Numerous firms have made progress; two exemplars being Zurich firm Gramazio & Kohler and Danish 3XN. 5.4. Case Studies – 3XN’s Louisiana Pavilion & Gramazio & Kohler’s Gantenbein Vineyard

5.1. Adaptive Attitudes Radical reform would be required in order to adopt a PFIBS. Such a move could only rationally be realised in a series of small steps, requiring much greater cohesion between the working partners than is currently seen. In order to transform the approach, three concepts must be incorporated into every construction programme. Once each has been addressed a truly eco-effective PFIBS will develop. The three steps are also by no means related solely to architecture and Intelligent Façades, the theories can be applied to almost any design field. 5.2. Removal of Non-Upcyclable Materials Any product that cannot be broken down into its constituent elements and/or contains materials that cannot be recycled - cannot be upcycled. Such products should not be used. Ideally BREEAM and LEED would perform an LCA on every market product and material. Components that do not comply with stringent rules regarding future usage would be immediately removed from the marketplace, this being enforced through statutory Building Regulations. Whilst this may seem a rather authoritarian way of approaching the subject, developers looking to cut corners and costs will not adhere to voluntary codes or suggested guidelines. As Albert Einstein observed, "No problem can be solved by the same consciousness that created it. We need to see the world anew" [4], therefore to ensure this, ecological design must be stipulated as a ruling. McDonough & Braungart describe this as “Signalling Your Intention” and is part of their ‘Five Guiding Principles’ for establishing eco-effective design. Once this is achieved the consideration of a material's environmental properties will become second nature, rather than the ‘add-on’ it currently is. 5.3. Embracement of Innovative Technologies Given the need for Upcyclable replacements for all building componentry currently available on the market, a great deal of investment is required up front for this to become a reality. A recent report by the Committee on Climate Change, an independent body established to advise the UK government, called for a substantial increase in the funding available for sustainable technologies and green energy [5]. The report suggested the UK had a unique opportunity during the global economic recession to become a world leader in the research and development of ecological endeavour, indeed not investing would actually prove a false economy. Whilst the onus is very much on governments to instate legislation and provide research capital to ensure eco-effective design is successful, a large responsibility remains with the architect. Converting to a new environmentally led design system will prove an enormous challenge for many

The Louisiana Pavilion (Fig.3) exemplifies 3XN’s approach. Based on the closed loop concept, the Pavilion is designed to fulfil its own energy demands, be fully Upcyclable, and totally maintenance free. The structure is built from a bio-composite of natural flax fibres and cork bonded with Ashland’s bio-resin Envirez. Subsequently it is 100% biodegradable. Nano-X's TiO2 nanoparticles were applied to the substrate, meaning the pavilion is self-cleaning under precipitation as the coating causes the catalytic oxidation of organic contaminants when under direct UV sunlight. Flexcell’s Flexible Photovoltaic panels harness solar radiation for electricity, as do Noliac’s Piezoelectric crystals which deform under the weight of visitor footprints. The power is stored and used to light LED’s at night. The form was originally created by hand using a Möbius strip. It was subsequently parametrically modelled using Grasshopper for Rhino in order for the Engineering and detailed design work to take place.

Figure 3: 3XN’s Louisiana Pavilion.

At the Gantenbein Vineyard in Fläsch, Switzerland, Gramazio & Kohler used a robotic production method to lay 20,000 bricks precisely, at the exact interval and angle as prescribed by programmed parameters (Fig 4). The pattern imitates abstract oversized grapes, designed using a generative process replicating grapes falling into a 'basket' - the building volume. Each individual brick was then digitally rotated to form the constantly changing simulated image. A robotic arm is directly driven by the design data, meaning there is no need for drawings. The digital sequence also controls applying the bonding agent. This additive process is intrinsically sustainable, for no waste is ever generated. If a biologically derived adhesive is applied, then the entire façade is also upcyclable as the individual bricks can be separated.

Figure 4: Gantenbein Vineyard by Gramazio & Kohler.

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With reference to these two examples of a digitally supported eco-effective design and to previously mentioned research into façade composition, it can be summarised that for an Intelligent Façades to fully satisfy a Cradle-to-Cradle process the following four criteria are critical. 1. The adoption of Private Finance Initiative Building System (PFIBS); 2. The Removal of non-upcyclable materials from the marketplace through building control and regulation. 3. Embracement of Innovative sustainable Technologies. 4. The utilisation of advancements in Computer Aided Design. Adoption of physical methods of representation using digital fabrication.

8. REFERENCES [1] DEFRA Municipal Waste Management Survey England & Wales. London: ONS (2005). [2] W. McDonough, & M. Braungart, Cradle to Cradle: remaking the way we think things. New York: North Point Press (2002). [3] J. Lovelock, The Revenge of Gaia. London: Puffin Books (2006). [4] A. Einstein, Only Then Shall We Find Courage. New York: Times Magazine (1946). [5] CCC, Building a Low Carbon Economy. London: Seacourt (2010). [6] B. Anson, I’ll Fight You for It: Behind the Struggle for Covent Garden (1966–1974). London: Jonathan Cape (1981).

6. CONCLUSION This paper considers the possibility of an Intelligent Façade capable of encompassing an entire technological life cycle. From the outset an understanding of Cradle-to-Cradle concepts was imperative, leading to a methodology of ecoeffectiveness rather than eco-efficiency. In the present architectural landscape leading examples of façade design are increasingly double skins with integrated building management systems. They justifiably declare their environmental prowess and are indeed advancements in an eco-efficient sense. The next evolution should now enter an ecoeffective era. One inspired by the circular metabolisms of natural ecosystems. Envisage facades analogous to leaves that fall in autumn, to be remoulded and reinvented at the end of their design life. Not recycled, but upcycled to more innovative, higher environmental value products. Facades are changing all around us in any event. Companies continually rebrand and repackage themselves, often materialising into replacement façades. If building frames are considered permanent, then facades are temporary and capable of upgrade. To facilitate this design attitude and government legislation must adapt, in combination with the adoption of innovative materials and constructional techniques that have been described in this study. If the Cradle-to-Cradle philosophy is to be completed, it could be argued that the eco-effective fabrication and management of facades is inevitable as raw materials become increasingly more difficult to acquire. While manufacturers such as Lindner are now apportioning more resources to the development of these products, any eco-effective method may only succeed if both client and designer meet the challenge with similar economic or ethical foresight.

7. ACKNOWLEDGEMENTS Thanks must go to John Libby, Ludwig Schmid & Ulrich Untergehrer from Lindner, Tobias Bonwetsch & Prof. Matthias Kohler at Zurich ETH and Kasper Guldager Jørgensen at GXN/3XN.

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Hemp Lime Bio-composite in Construction A study into the performance and application of hemp lime biocomposite as a construction material in Ireland.

Patrick Daly BESRaC, ileeid Zero Energy House, Clonkill, Mullingar, Co Westmeath, Ireland

ABSTRACT: This paper presents the outcome of a scoping study carried out under the Irish Environmental Protection Agency STRIVE research funding programme into the potential application of hemp lime as a building material in Ireland.. The study collated a growing body of international research on hemp lime and its increasing application in construction, and summarised this in terms of the materials properties and performance in relation to standards and requirements for construction application in Ireland. This paper examines the materials application in construction, summarises the known material performances, and limitations in cross comparison of same, and presents a comparison of life cycle data for a hemp lime wall, based on a French study, and a traditional form of construction in Ireland, partial fill cavity wall construction, based on elemental European data, undertaken by the authors. Key advantages of the bio-composite were found to be its carbon sequestration capacity, (which had important impacts on the materials Global Warming Potential), its thermal performance, especially in dynamic terms with studies indicating favourable decrement delay resulting in stabilisation of temperature, and important hygroscopic properties which can have positive effects on relative humidity stability. Keywords: Hemp, Lime, Energy, Environmental Impact, Global Warming Potential, Life Cycle Analysis, Carbon Sequestration. 2.2. Masonry

1. HEMP LIME Hemp lime is a bio-composite material formed by the mixture of the woody core of the hemp plant, also known as ‘hurd’, and a lime based binder. After setting, the composite forms a rigid lightweight material and has potential applications to a range of construction solutions with claimed benefits of good thermal properties, thermal mass, vapour permeability, low environmental impact and carbon sequestration.

2. CONSTRUCTION APPLICATION 2.1.

In-situ infill

The predominant use of hemp lime as a biocomposite in construction to date has been as an insulating infill cast or sprayed in walls, roofs and floors. Hemp lime for wall infill is used in combination with a structural timber frame, the mix being either poured and tamped into temporary shuttering or sprayed onto an internal or external permanent shuttering.[1] For roofs a lighter mix, with better insulation qualities, can be applied by using an internal permanent shuttering and by spraying the mix between the rafters. Hemp lime may also be cast as a solid floor slab, can serve as a screed and has been used with under-floor heating. [2]

Hemp lime has been used to manufacture masonry blocks, generally for non load bearing infill walls on framed structures, however load bearing blocks of up to 3N/mm2 have also been developed, and research has shown higher strength potential with cement additive. [3] [4] 2.3. Precast Units / Panels Hemp lime has been applied in the form of large prefabricated panels by using timber cassettes, which were filled with a sprayed mix. [5] The wine society warehouse (Hertfordshire, UK) employed 3 hemp lime for the construction of a 50,000 m warehouse housing more than 3.5 million bottles of wine, via the production of pre-fabricated 3.6 by 2.4 m panels of 400mm thick-sprayed material within timber cassettes. [6] Such panels can be supported by a structural frame and provide both insulation and thermal mass. Precast applications are envisaged as a potential area for additional application of hemp lime cement solutions with possible weight, flexural strength and environmental benefits. 2.4. Other Hemp Applications / Developments In addition to hemp lime solutions hemp is already available as quilt insulation with hemp fibre

1

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

insulation batts. [2] Hemp also has potential to be used in cladding and boarding applications such as strand board, chip board, fibre board etc. with some boards already on the market. [2] There are also developments in hemp magnesium oxide/chloride and research being conducted on hemp earth/clay materials. [7]

3.3. Resistance to Moisture / Weathering The evidence from demonstration projects and some testing indicates that correctly specified and detailed hemp lime constructions with appropriate renders can provide adequate resistance to moisture. Water penetration tests on a rendered proprietary hemp lime mix, in a timber frame infill solution, were carried out by the BRE (UK), with water spray levels similar to one year of wind driven rain applied over a 96 hours period. The results showed that absorption did not exceed an average 50-70mm depth. [9] The earliest known hemp lime construction dates over 20 years without known weathering or durability failures. Importantly lime renders have been used extensively on many historical buildings and is known to function as a moisture and weather resistant layer, once specified and applied correctly.

Figure 1: Hemp-lime being spray applied into a timber frame with single shuttering. Source Lime Technology

3. HEMP LIME PERFORMANCES 3.1. Structure The compressive strengths of hemp lime as a material depends on mix proportions, compaction, application and intended use (load or non load bearing). For lightweight ‘infill’ construction typical reported values range between 0.5 and 1.0 N/mm2 for densities between 250 and 990 kg/m3 and 3 averages around 500 kg/m .[8] The BRE have also undertaken tests normally used for rigid cellular 2 plastic with values of 0.458 to 0.836 N/mm reported. [9] For masonry, reported values range between 1.0 N/mm2 (thermal blocks) and 3.0 N/mm2 (structural blocks) based on EN 722-1.[10],[11] However, research shows that with the addition of sand and cement, with higher densities, hemp lime can reach greater compressive strengths. [12] 3.2. Fire Safety Fire tests have been carried out on various proprietary mixes of hemp lime, both in masonry and timber frame infill solutions, with successful results. In terms of resistance to fire, the evidence indicates that appropriately specified and constructed hemp lime walls, of certified material, either infill or masonry blocks, could achieve up to 60 minutes fire resistance, however mixes could most likely be developed with higher fire resistances to 90 and possibly 120 minutes. With appropriate renders, tests show that specific hemp lime walls can achieve an A1 spread of flame resistance subject to the % of organic content in renders. [8]

3.4. Thermal / Energy Reported hemp lime thermal conductivity values range between 0.06 and 0.12 W/(mK) depending on the material mix proportions and density with corresponding variations in U-values. Subject to thickness and density contemporary maximum regulatory U Values in Ireland and the UK have been achieved and exceeded. [8] Importantly U values and associated steady state heat loss are limited in terms of accurately modelling actual heat flows in buildings, which are dynamic, and studies have shown important thermal storage and release characteristics in hemp lime, which could provide additional thermal performance. Simulation carried out using WUFI software shows that a 250mm thick hemp lime wall subject to sudden cooling of 20°C takes 72 hours to reach a steady state of heat transfer compared to 30 hours in cellular concrete and 12 hours in mineral wool of the same thickness. The energy lost from hemp lime in 2 the first 24 hours is 187KJ/m , which equates to an average heat loss of 0.11 W/[m2.K] despite the fact the theoretical U-value for this thickness of hemp 2 lime is 0.29 W/[m .K] [13]. This is evidence of how dynamic thermal performance can be different from predictions based on steady state figures. The same simulation provides evidence of the ability of hemp lime to almost completely (98.5%) dampen a sinusoidal change in external temperature of 20°C to 0°C over a 24 hour cycle with a time shift of 15 hours, the time delay of the peak temperature getting through the wall. This compares to a dampening of 77.5% for mineral wool with a time shift of only 6 hours and with a dampening of 95% for cellular concrete with a time delay of 10.5 hours . Similar conclusions are reached in another study where hemp lime is compared to baked clay bricks and cellular concrete. Materials are submitted to

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

various conditions of temperature and relative humidity. Hemp lime is characterised by lower temperature variation and it reaches a steady state after each modification as opposite to the other two materials where temperature continues to increase or decrease in the core of the wall. In terms of relative humidity, hemp lime shows important variations (around 15%) compared to other materials for which evolution of RH is rather constant [14]. In situ monitoring of Lime Technology offices built with 500mm hemp lime infill walls confirms the simulations mentioned above by showing that variations of external temperature and relative humidity result in constant values inside the building [15]. Hemp lime dynamic thermal properties have been exploited in the construction of a 4400m2 wine and beer distribution centre in Suffolk, UK. The building has the ability to maintain an internal temperature at between 11 and 13°C without the need for mechanical cooling or heating systems [16]. The materials properties, notably its thermal inertia, vapour permeability and hygroscopicity, are also claimed to improve the ability to dampen external temperature variations, reduce condensation, buffer moisture levels, and improve the comfort feeling inside the building.

hemp and the lime, which can effect setting and even binding, with key influencing factors being the moisture content of the hemp shiv, the ratio of water, timing of addition of water to mix, the mixing method and application (hand, mechanical spray applications), and the type of lime. As such proper materials and specification are important for successful application as is experience and quality in workmanship. It is important that care is taken to use appropriate materials and mix proportions, including binder proportions, and that adequate skill and knowledge is exercised in mixing and application method, including knowledge of material quality, equipment, materials, mixes, and local conditions. Given the innovative aspect of this material, training is vital for the industry to successfully use this material.

4. LIFE CYCLE ANALYSIS / COMPARISION 4.1. French Hemp Lime LCA An LCA of hemp lime construction which was carried out in 2006 and funded by the Ministry of Agriculture and Fisheries, examined the environmental impacts over a 100 year period from both the agricultural and the building process. [17]

3.5. Acoustics Research shows that hemp lime has a high standard of sound insulation owing to the innate porosity of the material; this creates a bigger surface area to absorb sound. In-situ tests carried out on sound transmission on hemp lime party walls in the UK Haverhill project measured a sound reduction up to 57 dB and lab research has given similar results [9]. As the mass of hemp lime is affected not only by the mix proportions and resulting material density but the manufacture process or site application / compaction, the acoustic properties could be improved by denser mixes, greater compaction and thickness, combined with detail solutions such as use of cavities. 3.6. Materials and Workmanship The development of hemp lime has lead to a range of mixes and blend applications both generic and proprietary, which include minor variations in hemp, binder and water ratios and more significant variations in binder constituent ratios and specification, some of which is proprietary information. Binder variations include lime type and proportions, (both hydraulic and hydrated lime), cement content, and additives. Research has highlighted important issues arising from binder blends and overall mix proportions and methods, which can effect the material properties and setting behaviour. There is also a reported competition for water between the

Figure 3: Functional unit of the 1 m2 French LCA study Cast Hemp Lime around timber frame. Source INRA 2006

4.2. Agriculture In terms of agricultural process, the study reported the potential environmental impacts of growing hemp were mainly due to nitrogenous fertiliser and transport. The effect of nitrogenous fertiliser consisted of greenhouse gas emissions, consumption of non-renewable energy resources and water pollution by nitrates. In terms of transport, the average distance travelled by the hemp straw in France was 100 km with resulting energy consumption and greenhouse gas emissions. There was also a large amount of dust produced with no final uses for this waste. 4.3. Construction In terms of building process, the study highlights a positive net impact on the greenhouse effect because the hemp-lime wall acts as a carbon sink over a period of at least 100 years as more carbon is captured by the shiv, timber and lime than that emitted over its lifecycle.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The production of the lime based binder is what most contributes to the emission of greenhouse gases, consumption of non-renewable energy, formation of photo-chemical ozone and resource depletion for the overall construction with Hemp having only a minor contribution by comparison. Transport is the main contributor to the destruction of the ozone layer and the second main contributor in terms of impacts on the consumption of non-renewable energy and the greenhouse effect. Table 1: Potential environmental impacts over 100 years for the construction of 1 m2 of hemp-lime wall cast around a timber frame. Source: authors adaptation from French LCA (INRA, 2006) Prod. of raw materials Construction Hemp Other shiv materials

Impacts

Resource depletion (kg Sb eq) Atmospheric acidification (kg SO2 eq) Greenhouse effect 100 years (kg CO2 eq) Destruction of the ozone layer (kg CF-11 eq) Formation of photochemical ozone (kg C2H4 eq) Non renewable energy (MJ) 3

Air pollution (m ) 3

Water pollution (m ) Generation of waste (kg)

-2

2.8*10

-2

7.7*10

-2

4.8*10

-7

3.3*10

-4

4.2*10

5.1*10 -45.9

7.1*10

0

0

2.6*10

-3

-3

1.3*10

0

0

0.2 -6

3.4*10

-3

5.0*10

265.8

19.9

674

207.2

14.6

2.2 n.a.

Transport (total)

1.2*10

52.3 4.3 6

End of life

-2

23.1

7.1*10

Use

1.3*10

-3

1.0*10-1 -35.5

-6

9.9*10

3.8*10

-4

5.4*10 394.2

0

6.7*10

0

0

5.7*10

-5

0

0

-2

6.1*10 0.9

0

0

56.3

0

0

128.2

0 0

0 0

-1

1.1*10 n.a.

In terms of acidification potential the hemp-lime 2 wall scores 0.1 kg of SO2eq/m against 0.15 kg of SO2eq/m2 for the traditional wall and as such contributes to the acidification of the environment to a lesser extent than the partial fill cavity wall.

-1

-1

-13.6 -7

4.5. Acidification Potential

Table 3. LCA comparison – Acidification Potential Source: produced by the authors

Total

-2

5.1*10

While data sources are not for the same country, they are European and should give a indication of comparative environmental impacts. The comparison has been made on constructions of the same wall U Value, to eliminate differences in heat losses and energy in use etc.

-6

-3

1024 6.7 104.9

4.4. Comparison to Partial Fill Cavity Wall A comparison of key environmental indicators was undertaken on the hemp-lime wall considered in the French study and a standard Irish partial fill cavity wall with a matching U-value. The table below shows the main components making up the traditional cavity wall assembly. Table 2: Partial fill cavity wall make up Source: produced by the author

Density 3 (kg/m ) lime cement render concrete blocks air gap expanded polystyrene concrete blocks gypsum plaster

Thickness (m)

1800 2000 -

0.02 0.1 0.04

30 2000 1300

0.06 0.1 0.018

4.6. Primary Energy (non renewable) PEI The non-renewable primary energy of the hemplime wall is equal to 394.2 MJ/m2 against 528.5 MJ/m2 for the traditional wall system, which is mainly explained by the lower energy input for the production of the different materials involved in their relative construction. Table 4. LCA comparison – Primary Energy Renewable Source: produced by the authors

Three major indicators have been compared: acidification potential, global warming potential, and non-renewable primary energy. Data for the hemplime wall has been extracted from the French LCA study, while that for the partial fill cavity wall has been based on density and volume calculations and raw data extracted from the Austrian database IBO, 2008 [18].

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

4.7. Global Warming Potential (GWP)

5. CONCLUSION

The global warming potential (100 years) of the hemp-lime wall is equal to -35.5 kg CO2eq/m2 against 40,5 kg CO2eq/m2 for the traditional wall system. The hemp-lime wall has a positive effect on global warming over its life-cycle because of its ability to capture carbon in the construction and the quantity of carbon captured by hemp shiv, timber and lime exceeds that emitted over their lifecycle. On the contrary, concrete materials and plastic based insulation produce high carbon emissions over their life cycle making the partial fill cavity wall an overall contributor to global warming.

This paper has provided a summary of the known principle performance data in relation to hemp lime, its growing application in construction and claimed environmental credentials most notable of which are its carbon sequestration capability, its thermal mass advantage and moisture properties.

Table 5. LCA comparison – Global Warming Potential (100 years) Source: produced by the authors

The data collated in this study was from multiple sources and research centres with variations in mixes, testing methods, and research objectives etc. meaning that establishing comparability of testing data to standards was not always possible and cross comparisons were sometimes limited or restricted. As such the report was limited in its information and only a generic account of the material was possible. However the weighting of this collated data and the various demonstration buildings undertaken to date, does indicate that appropriately specified, tested and certified hemp lime mixes, applied within its technical and engineering limitations, in well detailed and constructed building elements, with good standards of workmanship, could perform to many standards and requirements of guidance documents for building materials applicable in Ireland.

4.8. Further Improvements The environmental performance of hemp straw could be improved by reducing the application of nitrogenous fertilizer and by growing hemp varieties that make the best possible use of the available nitrogen. The reduction of the travelled distance by the hemp straw would also improve environmental performance. Developing final uses for the dust would further reduce the environmental impact of the hemp straw. Improvements in the emissions of greenhouse gases from the production of lime rely on its manufacturing industry. Shortening the transport between the factory producing the lime binder and distributors would also improve the overall potential impact of the building stage. The environmental performance could also be improved at the end-oflife with additional recycling options or recovery solutions that would return the sequestered carbon to the atmosphere as carbon dioxide instead of methane as in the case of landfills. The wood could be reused or burned to recover energy, while the hemp-lime used in composting operations as backfill or as soil improver

The study highlighted the limitations in assessing and comparing hemp lime performance to current construction standards as many of these standards were developed to assess the behaviour of traditional materials that behave in very different ways to hemp lime, meaning in some cases the testing methods themselves may be considered inappropriate or limited. For example compressive tests / standards for concrete blocks do not reflect the gradual deformation and ‘failure’ rate of more flexural materials such as hemp lime and this issue was reported at workshops and some studies. The need for a specific code or standard for hemp lime as a material in construction with testing requirements tailored to its specific performance behaviour was expressed at both industry consultation and technical workshops. Such a standard could be best forwarded by some form of representative body or group, whose formation is needed and should be supported.

6. ACKNOWLEDGEMENTS This paper has been written from a scoping study carried out under support from the Irish Environmental Protection Agency STRIVE research programme. Special thanks to Patxi Hernandez for his assistance in this project and Tom Woolley for his advice and input.

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th PLEA2011 - 27th Internationalon conference Passive Low Energy Architecture, Louvain-la-Neuve,Belgium, Belgium, 13-15 July 2011 PLEA 2011 - 27 Conference Passiveonand Lowand Energy Architecture, Louvain-la-Neuve, 13-15 July 2011.

8. REFERENCES [1] Daly P 2007 Lime Hemp – Mainstreaming Bio Composite Construction, Construct Ireland, Temple Media, Dublin, Ireland. [2] Bevan R & Woolley T, 2008, Hemp lime construction. A guide to building with hemp lime composites, IHS BRE Press, Bracknell, Berkshire, UK [3] Chanvribloc, 2009, Le Bloc de Chanvre, th Retrieved March 20 2010 from http://www.chanvribloc.com [4] Lime Technology, 2009b, Hemcrete® Structural Block Information Sheet. Lime Technology, 2009a, Hemcrete® Thermal Block Information Sheet Retrieved March 20, 2010 from http://www.limetechnology.co.uk [5] Modcell, 2010, Modcell Technical Sheet, Retrieved March 20, 2010 from http://www.modcell.co.uk [6] Lime Technology, 2010, Case Studies, Retrieved January 17, 2010 from http://www.limetechnology.co.uk

[15] Lime Technology, 2008a, The Thermal Performance of Tradical® Hemcrete®. [16] M. Lime Technology, 2008b, Temperature Controlled Warehousing - The Wine Society. [17] INRA, 2006, Étude des caracteristiques environnementales du chanvre par l'analyse de son cycle de vie, Ministère de l'Agriculture et de la Pêche [18] IBO - Austrian Insitute for Healthy and Ecological Building, 2008, PassivhausBauteilkatalog - Details for passive Houses, A catalogue of ecologically related constructions, Springer, Wien, New York .

[7] Busbridge, R 2009, Hemp-Clay: an initial investigation into the thermal, structural and environmental credentials of monolithic clay and hemp walls, MSc AEES, Centre for Alternative Technology, Machynlleth, Powys, Wales, UK [8] Daly et al, 2011 Hemp Lime Bio-composite as a Building Material in Irish Construction. EPA STRIVE Report 2009-ET-DS-2-S2. Scoping study report undertaken by BESRaC under EPA STRIVE funding, Dublin Ireland. [9] Building Research Establishment Ltd (BRE), 2000, DETR Framework Project Report : Field investigations of the thermal performance of construction elements as built, Glasgow: BRE [10] Bütschi P, Deschenaux C, Miao B, Srivastava, NK, 2003, Utilisation du chanvre pour la préfabrication d’éléments de construction, Proceedings of Annual Conference of the Canadian Society for Civil Engineering, Moncton, Nouveau-Brunswick, Canada [11] Bütschi P, Deschenaux C, Miao B, Srivastava, NK, 2004, Caractérisation d’une maçonnerie composée d’éléments en aggloméré de chanvre, Canadian Journal of Civil Engineering, v. 31(3), pp. 526-539. [12] Chew P, MacDougall C, 2007, Compressive Strength Testing of Hemp Mansory Mixtures, Proceedings of the International Conference on Sustainability in the Cement and Concrete Industry, Lillehammer, Norway. [13] Evrard A & De Herde A, 2005, Bioclimatic envelopes made of lime and hemp concrete, Architecture et Climat – Université catholique de Louvain, Louvain-la-Neuve, Belgium [14] Arnaud L, 2009, Comparative study of hygro thermal performances of building materials, Proceedings of the 11th International Conference on Non-conventional Materials and Technologies (NOCMAT 2009), Bath, UK.

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Impact of building’s wall lifespan on Greenhouse gas index according to the technical solutions chosen  

Marc Méquignon(a) (b) , Luc Adolphe(b) , Frederic Bonneaud(a) (a) LRA- Ecole Nationale Supérieure d’Architecture de Toulouse, France (b) LMDC- Institut National des Sciences Appliquées de Toulouse, France

ABSTRAC: This presentation focuses on the assessment of greenhouse gas emissions produced by buildings. We separate the contribution deriving from the use of the building to the one depending on the choice of the technical solutions. Our methodology is based on: (1) considering a wall area unit (i.e. 1sqm); (2) determining a long time span of service function; (3) choosing a technical solution in agreement with the specifications; (4) determining the lifespan of each technical solution (5) finding the corresponding greenhouse gas index in a appropriated database (6) simulating the time evolution of these indicators. Several technical solutions based on concrete, brick, stone, aerated concrete for example have been considered as well as lifespan from few years to centuries. The results of these tests are presented. They suggest that there is an impact of the lifespan on the performance of indicator of greenhouse gas emissions: the best technical solution considering a short time span may be the worst on a longer duration and vice versa. These initial results encourage us to examine the consequences on other themes: the impact of lifespan on the other sustainable development indicators; the impact of lifespan on the other component and entire building. Keywords: sustainability - lifespan – buildings - greenhouse gas - decision making

1. INTRODUCTION In recent decades, many studies have addressed the issues of energy consumption by buildings while in phase of use. They provided knowledge that lead to the production of many tools. The energy consumption by buildings has actually decreased. Thus, the relative share of the energy needed to achieve the buildings, as well as the associated environmental impacts, have increased. The European Committee for Standardization has established sizing and justification standards for building structures and civil engineering. In its EUROCODE 0 edition, the committee recommends ordinary lifespans for buildings according to use. The specified lifespan for the calculation of sizing for ordinary buildings such as housing is 50 years. Moreover, in the very interesting Environmental and Health Declaration Notes (FDES) of INIES building products database, « typical » lifespans are used to define the impacts of the Functional Unit (UF). These lifespans, are identical by definition whatever the product in the same function of use, do not allow to measure the impact of lifespan in the performance comparison. Regarding the choice of technical solutions for the manufacture of building, the aim of this study is to highlight the impact of their lifespan on greenhouse gas emissions (GHG) and to measure their importance. We propose in this paper to study the impact of lifespan of a bearing wall facade unit of a building housing, or 1 sqm, on GHG. The span of the function to fill in by our wall area unit is fixed. In order to compare different technical solutions, the method has been to characterize the need through functions that must be met by the wall with the help

of the development of synthetic functional specifications. This document allows us to propose different technical solutions satisfying all the desired functions with the same rigor. To assess the GHG emissions, we use the information provided in the base FDES from the INIES database, established on the basis of a full life-cycle assessment (LCA) which meets the ISO norm from the series 14040. In a first phase, we will fix on a hypothetical basis the lifespans of various options and we will evaluate the cumulative GHG over the life of the desired function. In a second phase, we will seek to provide a size scale of the impact from the choice of the technical solution. Finally, these livespans being not very « objectivable » considering our present means, we present for each of the solutions, changes in emissions based on changes in their own lifespan.

2 – STUDY METHODOLOGY 2.1

Conditions

The studied object is an outside bearing wall unit from a home style detached house. Location and environmental constraints are considered average. They are the same whatever the evaluated technical solution. Span of the evaluated function: The evolution of GHG emissions of this wall unit is measured for a function of use of 300 years. This may seem a long time. However, this choice reflects both the problem and the large number of centuryold homes in our cities. Whereas the function of accommodation, a duration of 300 years does not seem so extravagant as the needs may be considered temporally unlimited. It seems that no cause is likely to remove the physiological needs, of

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security, belonging and esteem in Maslow's sense, whatever the time scale considered. Qualitatively, the needs met by the function are changing but the old homes, sometimes several centuries old, seem to adapt to the changing original needs or to meet new needs [1], [2]. In 2006, in France, more than 5.33 million housing units were over a century old (source: INSEE). When the lifespan of the proposed technical solution is less than that of the function, the assumption is identical reconstruction and identical accounted data from those used originally. This hypothesis is simplistic because technological developments and means of producing energy are important. Nevertheless, the results produced in this article are determined considering current knowledge and practice.

Solutions adopted Outside Finishing mineral coating mineral coating mineral coating mineral coating mineral coating mineral coating mineral coating

When lifespan is longer than the remaining term of the function, the respect of equity will lead us to include the last index to the "prorata temporis". Wall unit study – Exerpt from simplified Functional Specifications The various solutions that are proposed, must meet the same functional specifications based on the NF X50-151 standard. Statement of need: The element must be able to bear structural and operating loads of another level while protecting the interior space and its occupants from external disturbances. Identification of the functions of service Elements of specifications Regular carrying function Insulation coefficient R=3.7 Regular interior and exterior finishing Different solutions meeting the specifications in the same way are available. These solutions are described in the Table 1.

Body

Isolant

Concrete block 200mm Wooden structure Multi cell brick Stone Aerated concrete 200 mm Full solid brick shuttered concrete

170 mm insulator LV 200mm insulator LV 40mm insulator LV 190 mm insulator LV 20 mm insulator LV 130mm insulator LV 80mm PSE + 50mm LV

Inside Finishing plasterboard plasterboard plasterboard plasterboard plasterboard plasterboard plasterboard

Table 1 : Technical solutions used

Notes: 1. It is admitted that the « stone » solution is not to be covered with a coating of mortar. 2. Adopte insulation whatever solution is glasswool 3. Strict conformity to the insulating function, neutralizing energy consumption during the operational phase, in some cases involves the addition of a thin insulator. If this design proposal is not realistic during the production phase, it is kept in an objective of scientific rigor. 4. Taking into account the impact of greenhouse gases by steam is in proportion to the thickness of the insulation. 5. Phenomena of convection are neglected 6. Potential impacts of internal steam transfers on comfort are neglected. 7. The various technical solutions have different inertia but the selection of a temperate climate allows to disregard energy consumption for summer comfort. This has been checked by tool TRNSYS on a type house. 8. The system for attaching the insulator is not considered because there are many different ones and the corresponding FDES do not exist 9. The insulator is considered as placed inside 10. Internal convection and permeability are neglected 11. Impacts of thermal bridges varying from one solution to another are neglected.

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12. The solution "raw soil", which performance is probably good, has not been assessed due to the lack of data. Data gathering and critics The data used are provided by the INIES database within the Environmental and Health Declaration Notes (FDES) conducted within the frame of the NF P01-010 standard. The latter is established on the basis of the ISO standard 14040 series fixing the conditions of the life cycle analysis. These are the values established throughout all the product life cycle (LCA). These values result from the addition of emissions through all stages from raw material extraction to demolition. Only the impacts related to production facilities are neglected. We can not use established values of functional units (FU). Typical lifespans, by definition are identical whatever the product with the same function, and do not allow a comparison of performances of different technical solutions throughout time. How could one imagine that a solid wood frame has the same lifespan as a frame made out with trusses? With the objective of evaluating the impact of lifespan of different technical solutions on environmental performance and enable comparison, we use values of the entire cycle. The index values of GHG emissions of products, thus retained for full life cycle, are considered constant over the period of 300 years. This hypothesis is simplistic because changing technology and modes of energy production are important. However, as explained in the paragraph about the lifespan of the function, the results found in

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this article are determined taking into account current knowledge and practice. Note: for wood products and storage of CO2, the INIES base provides negative values. Other databases, such as KBOB, provide positive values and therefore contradictory ones. The concept of storage of CO2, impacting CO2 emissions is the subject of different approaches depending on whether one accepts a storage long enough to be permanent, forests replanted or not, landfill at the end, ... Many articles present how difficult calculations are [3], [4], [5]. As shown, using negative values of GHG emissions, presents difficulties and even contradictions. We chose to keep the indexes from the INIES base, introducing in parallel a value from the KBOB source. 2.2

Development st

1 phase: Simulation of GHG emissions based on lifespan of solutions accepted as hypothetical During this first phase, lifespans are determined as hypothesis according to expert opinions. Evaluation of lifespans of the proposed solutions Evaluation of livespans may be the result of experimental, in reliability, according to statistics or expert approaches [6]. This is by the method called « according to expert » [7], that we retain the assumptions of lifespans. This method, used within a first approach based on intervals, allows simulation that provides approximate results. Note: lifespan can come from the physical boundaries of the element itself answering its function but mostly from the functional obsolescence of the product or building. Lifespans are described in the table 2:

Stone

Sources Lifespan 40-60 Industrials and scientists 25-35 Technical Director HLM 500-1500 On existing

Wood frame

60-80

Solid bricks

250-350

On existing

Concrete blocks

100

Builder

Aerated concrete

100

Builder

Multi cell bricks

100

Builder

Type of wall Insulator LV Exterior rendering

2

nd

phase: variable lifespans Lifespan of a product is difficult to be objectified. For this reason, during this phase, lifespans of the different solutions are variables. Evaluation is performed without any a priori on product lifespans. This phase assesses the impact of lifespan of the solution itself on its own results but also allows to compare the solutions to each other.

3 - RÉSULTS Result 1: Processed data in determined conditions give these results: Type of wall Wooden frame INIES index Stone Wooden frame KBOB index Concrete block Shuttered concrete Solid brick Multi cell brick Aerated concrete

Kg éqCo2 at 70 years (Column 1) -5 32 25 48 86 114 65 65

Kg éqCo2 at 300 years (Column 2) 1 57 107 148 166 178 200 211

Table 3 : results index levels at 70 and 300 years

 

Chief of mission cultural heritage Quebec/ Practitioner Shuttered concrete 180- 200 Concrete engineer

:

Data processing The technique used is cumulative index values, established in the LCA, during the function of 300 years. This simple technique allows for the results on span and for observation on the changes in time accordingly.

In this table 3, the first column refers to values of emissions in kg eq CO2 added over 70 years, including all the components of technical solution The second column refers to the values of emissions in kg eq CO2 added over 300 years, including all the components Notes: - indicators for the solid brick are specific calculation from sheets of products of the same material: full coating brick -­‐   Since there is no FDES reference in INIES for wood, the impact of the wood solution is assessed on the basis of other "wood" products.   The variations cumulated of GHG overtime are represented in the chart 1 below.

Table 2: Estimated lifespan

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Chart 1: sum of GHG emissions to answer the function

Result 2: Relative importance of the choice of technical solution considering typical housing

Result 3: Impact solutions on GHG

According to the assumption of the first phase, we can assess the significance of the difference of impacts between the choices of extreme performance solutions. The average surface of a home in France is 91 sqm in 2006 (source: INSEE). This represents a typical example, about 78 sqm of bearing wall. Then the result is converted on the basis of impact of annual trips made with an average car (120 g CO2/ km). Less performing solution: aerated concrete, (kg eq CO2) 211 Most performing solution: bois, (kg eq CO2) 0,79 Difference for lifespan of function 300 years 210 Annual difference for one home -3 63,69 (10 kg éq CO2) Equivalent distance in km (based on -3 an average car exhaust 120x10 Kg eq CO2) 449,09

In this second phase, we calculated the level of GHG emissions to meet the public use for 300 years, depending on lifespan of the technical solutions chosen. Changes in emissions are represented by the curves in the chart 2. The results show profiles of type of the inverted function « y=1/x ». We can notice: - Significant reductions in emissions for extensions from 50 to 100 years or 150 years; - The curve of the solution « wood INIES index », curves on an inverted trend compared to the others.

     

Chart 2 : Changing of emissions according to lifespan

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4 - DISCUSSION 4.1 Cumulative emissions. We can see several observations about table 3 and chart 1. The « wood » solution as measured by the INIES index is the most effective solution, whatever duration of use of the wall. This would allow total disappearance of GHG emissions. The negative value of the wood index (long-term storage of CO2) can offset greenhouse gases emitted by the mineral coating (renewed every 30 years) and the insulator (renewed every 50 years). If we consider the KBOB index, the performance is different. For a wall which lifespan is 70 years, the impact is equivalent to that of the « stone » solution. After this period, the « wood » solution shows a worse performance than the stone solution with an impact nearly 46% lower for the « stone » solution at 300 years. Overall, the « wood » solution seems to be a successful solution, whatever the lifespan. Indeed, except for the « stone » solution, whatever the origin of the index and the expected span of the function it is the most effective solution. Since the life of a wall is never known in advance with certainty, this solution limits the consequences of an « early » demolition and deals with uncertainty based on the precautionary principle. Note: These results show the contradiction of the two theories concerning the « wood » origin of products. A quick solution to this problem must be found if one wants to exploit the index values and consistent results. The « stone » solution is effective whatever the considered lifespan for our wall unit. This solution allows a significant reduction of between 44 and 73% emission for a period of 300 years compared to other solutions (wood INIES index not included). This performance is achieved through the extremely long lifespan found, energy requirement restricted at cutting, transport and implementation and finally with the absence of coating. In the case of building rapid obsolescence, the stone can be easily reused. Considering the current state of technology and existing products, this is probably the most recyclable solution. There is a paradox. These two solutions of stone and wood which are the most effective because they do not use energy for their transformation are the least ones used, at least in France. Then, we have less performing solutions. For a wall lifespan of less than 70 years, the « cellular concrete » and « multi cell brick» solutions, both having identical results, are preferable to « shuttered concrete » and « solid bricks » solutions. They provide respectively a reduction of 25% and 43% of emissions. Conversely, if you look at a longer period than 200 years, shuttered concrete is a more efficient solution with a reduction of respectively 17% and 21% compared to the « multi cell brick » and « cellular concrete ». The « full brick » solution allows a reduction of 11% and 15% when

respectively compared to the « multi cell brick » and « cellular concrete ». Therefore these latter solutions have relative performance closely related to their lifespan. Note: the « mud » solution has been discarded for lack of information related to the absence of FDES. This is unfortunate because this solution could only achieve a good performance. 4.2 Relative importance of the choice for the technical solution The difference in emissions between the extreme solutions for a home represents an annual motor vehicle travel of 449 km. This result reflects the impact of all the vertical bearing walls of a house with an average surface. This value does not seem excessive. However, it is necessary to apply, for example, to the whole 130 million units in the European area (source: Eurostat) 4.3 Impact of lifespan of technical solutions on GHG This third result allows for more analysis. The interest of extending lifespan is obvious. The EUROCODE 0 sets spans for calculations of the sizing of buildings based on statistical calculation of failure. If lifespan of 50 years as referred for common buildings became an objective for professionals, it is shown that it would not favor an optimization in terms of GHG emissions. Like shown in chart 3, setting the target at 100 or 150 years could lead to significant improved performance. Whatever the solution, to extend lifespan from 50 to 100 years can reduce emissions by 50%. The stretch of 300 years allows a reduction of 83% of emissions. It is also established that a solution presented as less performing may be just as good if lifespan is proportionately longer (dashed red marker). For example, a wood structure built (KBOB index source) for 75 years has a similar impact as a wall made of stone if kept for about 80 years, hollow concrete blocks for 140 years or cellular concrete for 225 years. Whatever the level of emissions allowed, there are equivalents on the basis of different lifespans. What is required from these observations is: - To obtain scientifically based assessments of product lifespans - To choose products in order to maximize the impacts of GHG while taking into account the wanted lifespan of buildings; - To design the buildings so that they give the best answer best to changing needs thus timing away obsolescence; - To educate the contractor in his choices during construction or in his decisions between potential renovation or demolition Note: The inverted curve of the « wood » solution, based on the INIES index, shows that this index cannot be used in the same manner as other product indexes. Used as is and as we have done for other products, it creates an ambiguity or could even mislead us. Indeed, it leads to absurd paradox: "The

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longer the lifespan, less its impact in terms of GHG is favorable." There would be an incentive to reduce lifespan by a few years, even a few days without any conditions about waste during the demolition ... It seems that this negative value is due to an amalgam of wood characteristics. It seems necessary to examine these specific characteristics and provide consistent information that will show the performance of valuable wood products

5 - CONCLUSION This study demonstrates the importance of lifespan of a building component on GHG This implies lifespan indications from EUROCODE to be reviewed. By indicating lifespans of 50 years for current buildings, and although the objective is a design based on a calculation of failure probability, this European standard will result in the building industry to try to nearer the value for economy reasons. It seems that for this criterion of GHG, the standard should encourage greater performance for the building lifespan. This would result in significant emission reductions. Lifespans are much higher than observed in reality. The analysis of building product impacts in their life cycle allowed a profound breakthrough in the field of sustainable development. The FDES provide on the LCA basis a lot of useful information. However, the index values of functional units can not be used as is. The qualities of the products and technical solutions chosen have obviously an impact on decisions to keep or demolish a building. How can one imagine that a frame of trusses has the same lifespan as the solid wood solution? The demolition of trusses can be conceived after 50 or 100 years. It will be harder for the solid wood solution as the recycling of parts will be reasonably expected. It is necessary that manufacturers specify lifespan of their products by using scientifically established existing assessment tools. Designers and builders will then be able to adapt their choice and the quality of their project to the desired durability. This information would allow the optimization of emissions. Decisions for renovation or demolition should also consider the materials that were used originally in order to « cushion » the impact of greenhouse gases from the initial solution. Moreover, improving the functional flexibility of the building is expected to delay obsolescence and extend lifespan. This feature of the building falls within the architect’s field of competence and responsibility. It remains to study the impact of other components lifespan and of the building itself on this index. Is there a lifespan and a choice of optimal solution considering this criterion? What are the impacts of lifespan on other indexes such as the depletion of natural resources, economic indexes, social indexes or even culture? Lifespan of a building is an elusive characteristic. It is often the obsolescence of the building that generates its demolition and not the mechanical structure. To design and build in a responsible way, architect and contractor should be

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able to better understand these lifespan issues and their consequences. The difficult assessment of wood products requires a quick consensus that allows to provide usable data in the choice of technical solutions. These initial results encourage us to examine the consequences on other themes: the impact of lifespan on the other sustainable development indicators; the impact of lifespan on the other component and entire building.

6. BIBLIOGRAPHY [1]

Simon, Philippe. (1997). Architectures transformées : Réhabilitations et reconversions à Paris. Paris : pavillon de l’Arsenal

[2] Latham, Derek. (2001). Creative re-use of buildings. Volume 1. Shaftesbury : Donhead. [3] Vial E., Cornillier C., 2009 « Accounting for temporary biomass carbon storage in environmental » Labelling, International Conference on Carbon Storage in Wood Products, Brussels, 1 September 2009 [4] Barlaz M (2006): Forest products decomposition in municipal solid waste landfills: Waste Management 26 (2006): 321-333 [5] Gustavsson L, Pingoud K, Sathre R (2006): Carbon dioxide balance of woodsubstitution: Comparing concrete- and wood-framed buildings. Mitigation and Adaptation Strategies for Global Change 11, 667–691 [6] Talon A. (2006), Evaluation des scénarii de dégradation des produits de construction. Thèse de doctorat : Génie civil : UNIVERSITE BLAISE PASCAL – CLERMONT II 2006. [7] Bouchon-Meunier B., Marsala C., Logique floue, principes, aide à la décision, Paris, Lavoisier, 2003.

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Waste Management Various aspects in city of Pune, India. arti PATIL Architect, planner M.M. College of architecture, Pune, India ABSTRACT: Waste is related to the growth and development of human society, it has become a major environmental issue in India and is directly related to economy, it comprise countless different materials such as food wastes, packaging in the form of paper, metals, plastic or glass; discarded clothing and furnishing; garden waste, hazardous and radioactive wastes. Generation of waste depends on many factors like culture and nature of the people, the socio economic conditions, its commercial importance and its industrial base. Waste in urban areas would mainly consists of domestic waste, biomedical waste, industrial waste etc. The municipal solid waste contains organic as well as inorganic matter, a suitable waste processing and treatment technologies can be adopted by sanitary landfill, incineration, gasification, biodegradation process, anaerobic digestion. A rising urban population growth, dwindling municipal resources and the complexity of municipal solid waste management have complicated the relationship between environmental management and public health. High health risks of waste handling are associated with uncollected solid wastes with improper disposal of solid waste and with recycling. Planning and technology selection needs to be done to achieve an efficient and sustainable system of solid waste management. The intent is to look at the various aspects of waste management in context of the city of Pune in India. Keywords: municipal solid waste, generation, segregation of waste.

1. INTRODUCTION: 1.1 Indian Urban Development: The Urban population of India is growing at much faster rate than the overall rate of population growth. It has increased by 5 times as compared to the population growth of 2.5 times during last 5 decades. It is estimated that about 410 million Indians will be living in the cities by 2012 and 800 million by 2045. Table 1: Future prediction of urban population, GDP / capita and municipal solid waste generation / capita of India

Urban population (% in Total)

GDP per Capita (%)

Municipal Solid waste generation per capita (Kg /day)

2007

17.35

5.3

0.75

2010

32.43

6.0

0.79

2030

12.28

7.0

0.97

Source: (World fact sheet, 2001) and (World bank, 2003)

Many people are moving to cities because of the available opportunities and the availability of infrastructure facilities. The economic growth of India has also brought in foreign investments and hence is increasing opportunities for locals. The infrastructure in the metros of India is under severe stress and will crumble in a few years if there are no suitable measures taken. Pollution is increasing,

transportation systems are in disorder, water and sewage system are decrepit and failing. Due to urbanization production of municipal solid waste is at alarming rate. 1.2 Solid Waste Management in Urban areas : Municipal Solid Waste has been increasing proportionately with the growth of urban population. The uncontrolled growth in urban areas has left many Indian cities deficient in infrastructural services. Solid waste management has become a major environmental issue. Table 2: Solid waste generation rate in Indian Metropolitan cities

City

1971-73

1986-87

1994

Bangalore

0.32

--

0.48

Chennai

0.32

--

0.66

Delhi

0.21

--

0.48

Mumbai

0.32

--

0.66

Nagpur

0.22

--

0.27

Pune

0.24

0.28

0.31

Source: TEDDY, 2001-02

In many cities nearly half of solid waste generated remains unattended, giving rise to insanitary conditions especially in densely populated slums. Disposal in the landfills or uncontrolled

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dumping is the practice followed by most municipal bodies which poses threat to human health and the environment because it causes land pollution. In India composting is used around 10-12% respectively because composting needs segregation of waste and sorting is not widely practiced. It is estimated that about 1,00,000 MT of MSW is generated daily in the country. Per capita waste generation in major cities ranges from 0.20kg to 0.6 kg. Generally the collection efficiency ranges between 70 to 90% in major metro cities whereas in several smaller cities the collection efficiency is below 50%.

2.

TYPES OF URBAN WASTES

Figure 1: Waste characteristics of Pune

Urban waste in classified as various types according to the sources it is generated because each has its own collection and treatment processes.

Source: Assessment of Status of Municipal Solid Waste Management in Metro Cities and State Capitals. MPCB and NEERI

Urban waste is generated by following variety of sources

Uncovered garbage collectors, open dumping, leachate problem, animals roaming freely and scavengers picking through the waste are a common sight in all parts of the city. 15 hectares of the allotted 43 hectares for land-filling at Urali- Devachi have already been filled completely and sealed off permanently. Waste in the landfill is often burnt. This produces massive quantities of smoke and dust resulting in respiratory problems for surrounding residents. This unscientific method for disposing solid waste is a major cause for air pollution. It is also surely a substantial reason for global warming.

2.1 Household: It is waste generated by household and basically consists of things that are used in urban life. Urban household waste consists of papers, cardboards, glass and plastics. Some of these urban wastes are recyclable whereas some are not recyclable. 2.2 Commercial urban waste: It consists of waste from commercial establishments such as shops, restaurants, malls etc. These urban wastes mainly consist of packaging papers waste and organic waste 2.3 Institutional urban waste: This type of urban waste consists of public and private institute which belong to service sector. The amount of this urban waste and its composition is not known. 2.4 Industrial urban waste: Urban industrial waste is most dangerous as it contains many hazardous chemicals that pollute environment and cause various problems fir human life. Industries release heat waste, waste chemicals, waste residues etc. 2.5 The urban waste landfills that are not often waterproof often represent groundwater pollution by release of nitrates and nitrites as well as other pollutants. Landfill ex filtration and water leakage on slopes affect adversely the quality of adjoining soil. Urban waste landfills should therefore be reduced. 2.6 Bio-Medical Waste: Waste generated during diagnosis, treatment or immunization of human beings or animals, or in the production or testing of organisms.

3.

SOLID WASTE MANAGEMENT FOR PUNE.

Pune is a rapidly growing city. As its size increases so does the spewing out of waste. The city is currently caught in a predicament with large volumes of waste on one hand and the rising cost, land requirement and inability of human, technical, financial resources involved in managing such waste on the other. Urban waste management is a fast becoming one of the biggest problems the city is facing.

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In addition, solid waste landfills give rise to leaching of soil. The leachate generated by these dumps has high organic contents, soluble salts and other chemicals. These mix with the ground water tables, thus polluting them, which in turn spread diseases like jaundice, cholera etc. Nevertheless, efforts are now being made to treat and reduce waste. There are some waste recycling plants run in the private sector which produce compost for commercial use. The municipal corporation is also involved and state of the art biological decomposition methods for waste treatment are being applied. However there is a drawback – the (EM) Extra Molecular culture used on waste cannot treat the non-segregated waste completely, rendering the process partly useless. Thus solid waste management at a micro level is essential, where reduction, segregation and disposal of waste at every individual level dealt with.

4.

WASTE GENERATED :

With the city expanding, Pune has a rapidly changing waste quantity. The city generates 1200-1300 metric tonnes of solid waste every day. The per capita generation varies between 229 to 504 gm/day amongst different wards. Municipal Solid Waste contains on an average between 30 to 50% organics, about 4-6% recyclable and certain constituents having high calorific value. About 40% of the waste is generated from households followed by hotels, restaurants and other commercial establishments which together account over 50% of the waste generated. Pune has over 565 healthcare facilities roughly amounting to 6829 beds. Thus the bio

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medical waste generated from these hospitals is around 2560 kg/day.

5. SEGREGATION OF WASTE, RECYCLE & REUSE : Tonnes of garbage is segregated everyday in the city. Dry waste is separated from wet biodegradable waste. Recyclable waste is given to agencies which buy the waste from the generator and re route it to the recycling process units. Non recyclable waste is collected in separate containers. Figure 2: Source wise quantity of waste generation in Pune

6. THE TRENDS OF TECHNOLOGIES ADOPTED / AVAILABLE FOR PROCESSING AND DISPOSAL OF MUNICIPAL SOLID WASTE ARE: 6.1 Composting / Vermiculture: Composting is a natural biological process that is carried out under controlled aerobic (requires oxygen) or anaerobic conditions( without oxygen). In Pune composting is widly practiced, over 900 housing societies are creating wealth from waste using vermiculture. Decomposing waste on their own has helped them avail of tax rebate plan. Figure 4: Household Vermiculture

Source: Report on Centrally sponsored scheme for solid waste management and drainage for IAF Airfield Town of Pune by HUDCO.

KKPKP( Kagad kach patra kashtakari panchayat) a ragpicker union working in Pune has promoted the segregation of dry and wet garbage at household level also ‘Swach’ a waste pickers organisation help the corporation; housing societies separate their wastes into biodegradable waste is decomposed creating wealth from waste using vermiculture and non- biodegradable is collected by authorities. Public bins and garbage collection by use of municipal trucks is in practice. Figure 3: Rag pickers at work

Vermiculture involves stabilization of organic waste through the joint action of earthworms and aerobic microorganisms. Initially, microbial decomposition of biodegradable organic matter occurs through extra cellular enzymatic activity (primary decomposition). Earthworms feed on partially decomposed matter, consuming five times their body weight of organic matter per day. The ingested food is further decomposed in the gut of the worms, resulting in particle size reduction. The worm cast is a fine, odorless and granular product. This product can serve as a bio fertilizer in agriculture. Vermi- composting has been used in residences. In Pune, for Vermi Composting / Bio Composting , 1500 units are in operation ,100 TPD is used in composting/vermi-composting , 550 units are non functional which needs to be revived and as a voluntary participation of citizens – more than 300 units are in operation. 6.2 Waste to Energy in terms of Biogas or power generation

Reuse and Recycle segregated by ragpickers or dumpsite and biodegradable waste is converted into manure by private companies.

Under the ‘Waste to Energy' Project, situated at Aditi Gardens at Magarpatta City, the Property Management Services Department (PMS) at the Magarpatta City collects and transports the garbage to the centralised garbage room. At the ‘Waste Management Department’ further processing of the garbage takes place. The uniqueness of this exercise is that no municipal garbage trucks are involved in garbage handling, as the entire process is carried out in-house.

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Organic waste is processed through Biogas, Organic Waste Converter (OWC) and VermiComposting process. Inorganic recyclable waste including paper, plastic, glass and metal is sorted out and sold to the vendors. This becomes a great source of revenue and contributes greatly in subsidising this exercise. At present, over 5000 flats -owners have taken possession and the waste collected every day in Magarpatta City is over 6.5 to 7 tonnes per day. Out of this, biodegradable waste is over 3,000 kgs. Non-biodegradable and recyclable waste is over 2,000 kgs. The non-biodegradable, non-recyclable, inorganic waste that goes for land filling is over 1,500 to 2,500 kgs. For the Biogas plant the waste form canteens from the commercial buildings is used. The generated gas is fed to a 50 KVA Biogas generator for power generation - which is utilised for pumps to water the garden. Near about 37 biomethanization Plants are working in City,taking care of 20 to 25 MTD of Solid Waste. Figure 5: Biogas plant at Magarpatta City, Pune

scrubber, waste autoclave, waste shredder, gas monitoring device and effluent treatment plant. The incinerators have the capacity to dispose 150 KG biomedical waste every hour. Figure 6: Incinerators

8. SANITARY LAND FILLING: Sanitary landfilling is an acceptable and recommended method for ultimate disposal of MSW. It is a necessary component of SWM, since all other options produce some residue that must be disposed off through landfilling. Presently, site at Urali Devachi is used for disposal of solid waste. Various residential, industrial and agricultural establishments are situated around this disposal area. The site has poor air quality and percolation of leachate which has high concentration of pollutants is responsible for the contamination of ground water. Figure 7: Garbage ladfills

7. INCINERATION : Incineration is the process of control and complete combustion, for burning solid wastes. It leads to energy recovery and destruction of toxic wastes, for example, waste from hospitals. The temperature in the incinerators varies between 980 and 2000 degree Centigrade. One of the most attractive features of the incineration process is that it can be used to reduce the original volume of combustible solid waste by80–90%. Some newer incinerators are designed to operate at temperatures high enough to produce a molten material, it may be possible to reduce the volume to about 5% or even less. In Pune, Passco environmental solutions, a private organization collects, segregates and disposes a total of 1500 KG. Bio-medical waste in the city on a daily basis picked from more than 400 points. There is one bio-medical waste disposal incinerator under P.M.C. run by Passco environmental solutions in Kailash crematorium premises, pune and another at P.C.M.C; chinchwad in Y.C.M. hospital. The facilities are equipped with incinerators with pollution controlling wet ventury

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Source: www.wieklenssenfilm.nl/images/upload//Garbage

The Pune Municipal Corporation (PMC) has proposed a solid waste management project to ensure that organic waste is treated and turned into manure at a site near Yeolewadi.The capacity of the project would be to treat 500 metric tonnes of solid waste per day. The project is proposed to be carried out on a build operate and transfer (BOT) basis. the municipal corporation has recently acquired 20 acres of land at Yeolewadi as part of its plan to decentralize the process of dumping of solid waste at the Urali garbage depot. The project will facilitate the treatment of organic waste in an environment friendly way and the non-organic waste would be recycled.  

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The PMC has already begun work on two separate projects at the Urali garbage depot. These include disposal of 500 metric tonnes of waste by mechanical composting, and disposal of another 100 metric tonnes by vermicomposting method.

9. PLANNING FOR SUSTAINABLE SYSTEM

EFFICIENT

AND

A proper planning and technology selection needs to be carried out and before implementation, the present and future ways to manage solid waste stream need to consider. Majority of the local bodies find it difficult to manage in improving the collection, transportation and disposal systems. Therefore resources can be generated through privatization of the services. Considering the high cost involved in waste management, the first priority of local bodies, even in the case of privatization should be waste minimization at source. Active participation of citizens is a prerequisite for waste minimization. Effective waste minimization can be achieved only through segregation of waste and diversion at the source of recyclable material to recycling centers through scrape-dealers or waste pickers. Door to door waste collection is absolutely essential for improving the waste collection efficiency. Organic waste or biodegradable waste can be treated and disposed off/ used as manure in the premises or it can be given to local municipality vehicle for further disposal. The non-biodegradable waste/ recyclable waste can be sold to the scrap dealers and for other inorganic hazardous waste MPCB (Maharashtra Pollution Control Board) and municipality can be contacted. Construction and demolition waste should be disposed off separately. Recycling/ reuse of such wastes should be encouraged. Excess packaging including plastic and thermocol that is difficult to recycle should be eliminated. Composting of kitchen and yard waste of the household and community level should be encouraged. Land filling should be limited to material that cannot be managed through preferable options. Materials entering land filling should be regulated and monitored to prevent the introduction of any hazardous substances. Land filling should be restricted to non-biodegradable, inert wastes that are not suitable either for recycling or for biological processing.

10. CONCLUSION: Pune as a city, in recent years has been undergoing a change. Development just for the sake of development is slowly being overcome to give way to emergence of careful planning and stress on sustainability in every aspect of life. The assumption that the environment has an infinite capacity to absorb pollutants is shattered. With increasing awareness about environment related issues, the mindset of the people is changing and efforts are being made to minimize the negative impact on the environment right from the grass root level.

Public participation and creating public awareness play a crucial role in improving the Municipal solid waste management system. Social awareness and initiation is a key factor for a long term solution to the waste management. Awareness campaigns are carried out at the local level explaining the importance of the desirable 3 R’s- Reduce, Reuse and Recycle. Adoption of decentralized pattern of solid waste segregation and disposal at it sources has reduced waste for final disposal considerably. The bold initiative of PMC in developing a stateof-the-art landfill facility to handle the MSW generated by the city of Pune has already marked in reduction of bad odour and the menace associated with the flies and birds. A daily earth cover of 15cm thickness and final cover of 60cm thickness which is applied over the compacted waste. This practice minimizes migration of leachate through soil strata, suppresses foul odour and improves the aesthetic value. Incineration of solid waste under oxygen deficient conditions is called gasification. The objective of gasification has generally been to produce fuel gas, which would be stored and used when required. Gasification can also be used for MSW treatment after drying, removing the inerts and shredding for size reduction. Involvement of the private sector, community participation will lead to socio-economically sustainable waste management solutions. Pune is finally confronting the fact that it is our responsibility to create and maintain a balanced and clean environment and to live environmentally sustainable lives.

11. REFERENCES: 1) Amar M.Dhere Chandrasekhar, B. Pawar, Pratapsingh B. Pardeshi and Dhanraj A. Patil, “Municipal solid waste disposal in Pune City-Analysis of air and ground water pollution”, current science, vol.95,no.6,25 September 2008,pp773-774 2)

ARTI pro Urban Communities and solid waste Management” available at http://delhigreens.com/2008/03/06/urbancommunities-and-solid-waste-management poses waste management technology which can recycle garbage into fuel available at http://punekar.in/site/2009/05/12/arti-proposes-wastemanagement-technology-which-can-recycle-garbageinto-fuel/ 12may 2009 3) Govind Singh, “Indian Express, “Smart uses of waste”,16 April 2009 4) Vaishali Anagal “Sustainable Urban Solid Waste Management-a case study of Pune, 10th National Conference on Technological Trends(NCTT09) 6-7 nov2009,pp241-248 5) India States of the Environment, Hazardous waste: Special reference to municipal solid waste management, 2001,pp133-149;

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http://cpcb.delhi.nic.in 6) Wealth from Waste, teri; editors,Banwari lal,M R V P Reddy 7) Sherwood c.Reed,E.Joe Middlebrooks,Ronald W. Crites; Natural systems for waste management &treatment. 8) Suchitra, M., Outside: Burnt or buried, garbage needs land, Down to Earth, 15 March 2007. 9) Allen, R. M., Braithwaite, A. and Hills, C., Trace organic compound in landfill gas at seven UK waste disposal sites. J. Environ. Sci. Technol., 1997. 10) Tripathi, R. D. Rai, U. N. and Baghel, V.S., The challenges of solid waste. Sci. Rep., June 2006. 11) Urali-Devachi Fire Depot Kept Fire, The Indian Express, Pune, 27 May 2006.

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12) Permissible limits of ambient air pollutants. Central Pollution Control Board, New Delhi; http://cpcb.delhi.nic.in/standard18.htm 13) Strategic action plan for integrated solid waste management plan, Pune (Volume 1) 14) Anupam Khajuria, ‘Estimation of municipal solid waste generation and landfill area in Asian developing countries’ Journal of environmental biology; 15) Other web references http://mpcb.mah.nic.in http://envfor.nic.in/cpcb http://www.environment.about.com http://www.edugreen.teri.res.in http://www.mcgm.gov.in http://www.epa.org http://timesofindia.com

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ARCHITECTURE AND SUSTAINABLE TAINABLE DEVELOPMENT, DEVELOPMENT Proceedings of PLEA 2011, Louvain-la-Neuve, Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Pressess universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The he application of ‘techno-mud’ ‘techno mud’ in residential buildings in Chile – A critical review. Mirentxu ULLOA1, Benson LAU1 1

Department of Architecture and Built Environment, University of Nottingham, United Kingdom

ABSTRACT: ‘Techno-mud’ is a raw earth building technique derived from vernacular vernacular earth constructions in Chile. It reduces impact and cost during construction and facilitates comfortable internal conditions for occupants. New buildings built in techno-mud techno have successfully resisted the latest large earthquake in Central Chile (February 2010). Knowledge base on this technique is inherently practical and accumulated experience experience, and no formal performance testing has been undertaken, and local regulations do not consider it as a proper building technique. This research is based on the comparison of a techno-mud dwelling to a standard construction type dwelling in Chile.. The techno-mud model was subsequently improved, and further tested in different Chilean climatic zones using dynamic simulation simulation to predict internal temperatures within a free running residential building. Results obtained under an adaptive thermal comfort approach predict compliance to the Chilean building regulations, and identify the possibility of using this material to improve indoor conditions with different degree of success in all four tested locations by primarily primarily reducing heating loads loads. The study concludes that this building material can achieve a satisfactory environmental performance without the need of any additional active environmental control features. However there are some concerns for cooling loads which would need to be addressed in further research. Keywords: techno-mud, comfort,, thermal performance, earth materials, materials residential.

1. INTRODUCTION This study is a response to the observation that techno-mud has a number of beneficial characteristics to offer designers and occupants, and that limited documentation of the technique reduces the potential of the material to be used more widely. The study focused on defining the measure of comfort mentioned by itss designers and if in its original location the material in fact successfully aids in the achievement of thermal comfort when compared to international standards. The general aims of this study were to analyse the feasibility of exporting the material to different ifferent locations with some success, if its performance could be improved once exported, and whether the material was fit to meet the local regulation standards.

structure, reinforced with vertical steel bars linked to the foundations of the building. The mud is then moulded directly over the structure. The mesh is a flexible element that allows diverse shapes, some of them quite far from the possibilities provided by the traditional techniques. Since 2006, the practice has 1 been using the mixes tested by Gernot Minke . From this point on, it can be said that techno-mud is a lightweight construction technique. This is unusual for earth structures. It basically means the loam has reduced some of its thermal mass to incorporate air, and improve insulation. This is where the technique becomes an interesting analysis subject. Due to its flexibility and lightness, in order to achieve three stories of maximum height while maintaining unusual shapes, load bearing techno techno-mud walls can be no thicker than 21 cm. In the case of non load bearing walls, optimum thickness reduces to 13 cm.

2. GENERALITIES 2.1. Techno-mud Techno-mud is a new raw earth, earthquake resistant technique developed loped in central Chile C by architectural practice ‘Sur Sur Tierra Arquitectura’. Arquitectura The term ‘Techno-mud’ has not been used in any English language literature.. This is a literal translation from the name of the technique in Spanish ‘Tecno ‘ Barro’, where ‘tecno’ is an abbreviation for ‘technological’ and ‘barro’ corresponds to the Spanish word for ‘mud’. Techno-mud was inspired by two traditional techniques. It is a mix between the ancient wattlewattle and-daub, and adobe. The technique has evolved from a metallic wattle-and-daub daub to what it is today, using folded metallic mesh as the main structural element, made from recycled steel as a primary

Figure 1: House in Peñalolen. Techno Techno-mud construction process.. Image courtesy of "Sur Tierra Arquitectura" Arquitectura". Also found and referred to as ‘tecno barro’ in ‘Earth 2 Architecture’

2.2. Climatic context, regulation and housing issues. Chile is located between latitudes 56° South to 17° South, resulting in a very diverse geograph geographic and climatic conditions. A common factor for all these climatic areas is the presence of earthquakes. Chile stands over an area where the Nazca and Antarctic plates are pushed under the South American plate.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

As a consequence, the country is severely affected by earthquakes. This is the reason why in terms of legislation, the existing regulations have a strong sense of seismic awareness. It is only in recent years that the need to specify for every distinct climate has 3 been acknowledged in the Thermal Regulation . Based initially on ASHRAE standards, the Chilean Thermal Regulation was planned to be implemented in three stages. To date, only the first stage is in operation, focusing on minimum transmittance requirements for specific materials and building elements depending on location, in order to avoid lower temperatures as latitude increases. Consequently, in colder climatic zones, better insulation is required. This being the case, the regulation does not make a point in overheating parameters, which will be considered at later stages. Unfortunately, with the exception of adobe, earth construction materials are not considered by the regulation. Additionally, as the regulation is based on a steady state analysis and focussing on transmittance, it is highly likely that any analysis of earth constructions from this perspective would result in a poor performance, as their u-values are notoriously high for a building construction material. The issues of residential deficit have been of great importance to Chilean government since the th 4 early 20 century . Although politics and regulations have changed in the past century, the main goal remains the same; to eradicate poverty and improve quality of life. During the past couple of decades, Chile has seen fast growth when compared to other 5 Latin American countries . The growing economy in the nineties has translated into an improvement in basic services, which has also changed the perspective of housing regulations. In the interest of establishing some targets related to thermal comfort and residential buildings indoor climate, parametric studies have been carried out, particularly for the Central Zone in Chile. The emphasis of such studies was to verify the feasibility of passive design, considering one construction technique, and different design features, and establishing comparisons between them. Conclusions show that insulation and the optimization of solar gains are of great importance. Creating larger openings on the north facing facade to increase solar gains feature among one of the main solutions. However, this option needed to be discarded for not complying with seismic regulation. The solution was to use a Trombe wall, sacrificing 6 daylight levels . Results generally show that in order to achieve thermal comfort, considering an entirely 7 passive design is a definite possibility . A wide range for study in the area, considering parametric simulations, is still available. Due to the variety of climates in Chile, it is not realistic to assume the existing results will be applicable throughout the country.

3. METHODOLOGY

city of Santiago, where density is very low. This guarantees optimum orientation, and no overshadowing from neighbouring constructions. The program considers a family unit of four people, consisting of two parents and two children. This also 8 matches the state of the average Chilean family .

Figure 2: General Plan - Courtesy of ‘Sur Tierra Arquitectura’

The building consists of a ground floor arrangement with three bedrooms and a large common space serving as main living area and kitchen, all of them oriented to the north to optimise solar gains (fig.1). Services and circulations are south facing. The exterior of the building is shaped in such a way as to deal with rain water drainage, and to diminish effects of erosion by rain and prevailing winds. The walls are also aided by the roof, which overhangs in some places to provide additional shelter.

Figure 3: Top to bottom: north, east, south & west facades.

3.2. Thermal performance analysis. This research is based on the comparison of the indoor temperature of a residential building, modelled in EDSL Tas. The modelled buildings consist of a standard construction model, Model A, and three subsequent models, B, C and D, where the primarily assigned material was techno-mud. Each of the four models was tested considering four different locations along Chile as the only variable (table 1). These included the original project location, in Santiago de Chile, and three other locations representative of the wide climatic diversity in the country.

3.1. Defining a generic residential design The analysed project is a private residence to be located in Pirque, a southern suburb of the capital

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 1: All different locations were chosen for their climatic variety, as well as their geopolitical relevance.

0

1

Location

Lat-Long

Climate

Regulation Zone

Santiago

33°26 S, 70°39 O

Continental Mediterranean

Zone 3

Antofagasta

23°38 S, 70°24 O

2

Concepcion

36°46 S, 73°03 O

3

Pta. Arenas

53°10 S, 70°56 O

Arid coastal with overcast skies Warm temperate, wet season and high RH Cold semi arid with wet season

Zone 1

Zone 4

Zone 7

A total of sixteen simulations were conducted as follows: Base Case – MODEL A: Initial model with traditional construction materials. Model A is a standard timber construction that complies with the thermal regulation by changing insulation specs of vertical elements of the envelope according to location (table 2). Results from this models were used to establish the minimum basic parameters for acceptable indoor temperatures in free running thermal regulation compliant residential buildings, as current regulation does not establish any such parameters. The percentage of hours within comfort range resulting from this model was considered the minimum acceptable results by which further models were compared. Case 1 – MODEL B: Techno-mud Project. The project will be modelled considering technomud as the main construction material (table 4), and tested in its original location, and three others. It doesn’t consider any additional strategies. Case 2 – MODEL C: Internal insulation. From the analysis of Model B, the first proposed measure for improving performance is one design variable. This variable consisted of insulation panels to be used on the outside of certain walls, only during the winter season. This model was tested in all four locations. Case 3 – MODEL D: Optimization of solar gains. From the analysis of Model C, a second change is proposed. In this case it refers to the orientation. The project has a north east orientation, which in this model is changed to an absolute north orientation. This is an evolution of Model C. It considers the insulation panels as well as the new orientation. This model was also tested in all four locations. Each of the previous models was simulated a total of four times, one for each location. .

Table 2: General assumptions for main vertical elements in the building envelope in Base Case – MODEL A (Standard Model), according to locations, as specified in the thermal regulation. Standard structural wall (‘Muro 2’ in regulation) Loc

Thickness

U-value

0-2

134mm

0.84

1

134mm

1.15

3

174mm

0.45

Insulation spec 20mm Exp. Polystyrene 10݇݃/݉ଷ 20mm air gap. No insulation required. 60mm Exp. Polystyrene 10݇݃/݉ଷ

Table 3: General assumptions for other materials in Base Case – MODEL A (Standard Model), not affected by thermal regulation, and common to all locations. Element

Thickness

U-value W/m²K

Insulation spec

Wall

124mm

0.592

50mm mineral wool

Roof

200mm

0.261

Glass fibre

0.29

None, Additional 1000mm soil

Floor

255mm

Table 4: General assumptions for techno mud elements in Case 1 – MODEL B, and subsequent techno-mud models (common to all locations)

200mm

0.56

2.8

1140

Thermal Capacity kJ/m³K 1200

120mm

0.56

4.6

1140

1200

Roof

200mm

0.187

0.93

720

518

Floor

200mm

Element Wall Partition

Thickness

Conductivity W/mK

U

W/m²K

Density Kg/m³

3.75

3.3. Performance prediction assumptions Techno mud modelling: The architects started 9 their experimentation based on Minke , who mentions that lightweight straw loam has a density of 1,200 kg/m3 or less, and has been tested to have a conductivity of 0.5 W/mK. Density has been proved to be reduced to 700 kg/m³. These extra lightweight loams have been tested to have a conductivity of 0.2 W/mK or less. In order to export these values to the building simulator, materials with similar characteristics were chosen to model the structural techno mud walls (envelope), and the extra light techno mud roof (table 4). Dependant variables: The only dependant variable considered was the weather data. This is the case for all models, with the exception of the Base Case, which was adapted for each location to comply with the Chilean thermal regulation, which mentions the most relevant parameter to influence internal conditions in winter is the level of insulation of the walls. Independent Variables: Design: All design features such as glazed area, orientation, geometry, shape, layout, have remained constant throughout all simulations. The residence was simulated considering four occupants: two adults and two children. Occupation: Occupation settings were based on 10 studies about the use of time in Santiago . In these studies, the main observation is that occupation is

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

more intense during weekends than working days. This pattern was assumed for the whole year. Ventilation: Due to the extremely different climates (which vary from extreme arid to extreme cold areas), assuming an invariable pattern of opening and closing of windows depending on different ventilation strategies or occupancy, was considered to be counterproductive counterproducti to the comparison purpose of the study, as this would influence results too greatly. The models were therefore considered to be air tight, with an even and constant infiltration of 0.2 air changes per hour, 24 hours a day. g to occupation, Internal heat gains: According internal gains consider lighting gains (bulbs), kitchen appliances, and occupants. 3.4. Setting comparison standards Although an initial analysis based on the standard approach was considered, the final results were 11 analyzed under the adaptive comfort approach . The comfort ranges varied with each location (table 5). These ranges were taken from the analysis of the 12 weather files from Energy Plus , as analyzed by the Weather Tool 2.0. The range used to analyze the models also considers the building ing to be a free running construction, which generally lowers the colder temperatures allowed within the comfort neutrality zone. The results were analyzed and compared considering each hour of the year, and classifying them into one of the following three thre categories: “Above comfort”, “Within comfort”, and “Below comfort”, with special attention to hottest and coldest week of the year. Additionally, an overheating 13 benchmark was also applied . The “above comfort” index included all the overheating hours.

passive strategy, like night time cooling. Ventilation strategies were replaced by even iinfiltration rates, which lead to expected overheating during summer. Design features have also remained constant, although the building was designed for better performance in its original location in the Santiago area. Occupancy patterns, and therefore lig lighting and appliances gains, have also been simplified. A usual occurrence in heavyweight buildings where earth is the main construction material, higher indoor temperatures are usually achieved during night time. This was the registered case in most of the simulations run for this study, although technomud can be considered to be a lightweight earth material. This can be used to the advantage of heating or cooling strategies, and needs to be considered during early stages of design, together with general layout ayout and other strategies. In the particular case of the analyzed residence, the higher temperatures were reached around 22:00 hrs, usually in the bedrooms. This can be explained due to the house layout, where bedrooms openings take up most of the north facing façade façade. This has a very notorious effect especially in the analysis of overheating and temperatures above comfort range. In the case of the bedrooms, the occupied hours occurred between 21:00 hrs and 10:00 hrs the following day. Additionally, the hi higher operative temperature for activities carried out in bedrooms, as 14 specified by CIBSE, is of 23°C . This sum of factors helped in producing a high percentage of hours of discomfort above the thermal neutrality zone. Figure 38 shows above comfort percen percentage In bedrooms is always greater than in the living areas areas.

Table 5: Analysed results for Location 0: Santiago (‘Zone 3’ in regulation classification). LOC Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0 max 25 25 24 22 20 18 19 19 20 22 24 25

0 min 21 21 20 18 16 14 15 15 16 18 20 21

1 max 25 25 24 24 23 22 21 22 23 24 24 25

1 min 21 21 20 20 19 18 17 18 19 20 20 21

2 max 23 23 22 21 20 19 19 19 20 21 22 23

2 min 19 19 18 17 16 15 15 15 16 17 18 19

3 max 20 19 18 17 16 15 15 15 16 17 18 19

3 min 16 15 14 13 12 11 11 11 12 13 14 15

4. RESULTS 4.1. Analysis Some expected repetitive patterns could be observed during the analysis of results, such as similar indoor temperature behaviour curves for all locations and simulations, regardless of outside temperatures. This can be explained due to the test limitations. In order to simplify the process and focus on the resulting temperatures, the study has not considered factors such as humidity or any other

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Figure 4: Comparative graphic, showing the percentage of hours within comfort range for each location, for each model (adaptive comfort). The results for Model A (all locations) are the minimum standard tandard with which subsequent results were measured.

4.2. Summary This study has defined that techno-mud can be used as a sound construction material in certain areas in Chile, forming and supporting the building

MATERIAL (ENVIRONMENTAL AND HEALTH ASPECTS) / WASTE MANAGEMENT

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Neuve, Belgium, 13 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

envelope while successfully maintaining indoor temperatures emperatures within comfort standards. The study shows the standard can be raised when techno-mud is applied as main construction material in free running buildings. mud can be More specifically, techno-mud successfully applied in Location 0, Location 1 and Location ation 2. These correspond to Zone 1, Zone 3 and Zone 4 of the Chilean Thermal Regulation (tables 6, 7 & 8). The first observation when analysing results from the adaptive comfort approach is that the lower threshold adjusts to allow in lower minimum temperatures during the cold season, generally reducing the need for extra heating in winter months. This renders the readings generally less successful in term of dealing with higher temperatures. On the other hand, none of the models have ha considered additional techniques to reduce cooling loads, apart from the use of techno-mud.. There are still improvements to be studied in this regard.

difference fference is not as pronounced.

Figure 8: Both models behave in similar ways during coldest week in a colder location.

In the adaptive comfort approach, where discomfort percentage is greater for temperatures above comfort, Model B, which considers technomud only, becomes the most successful solution in terms of achieved comfort (figs. 5 & 7) 7). As we saw from the standard analysis, techno-mud lowers average indoor temperatures. In that scenario Model B was the best to deal with high temperatures. This is not ot only repeated here, but enhanced, since higher acceptable temperatures tend to be lower in this approach. At the same time, lower temperatures are dealt with by the adaptive range itself, which allows them, reducing the need for additional cooling (fig. 6), with the exception of the coldest location (fig. 8) Table 6: Analysed results for Location 0: Santiago (‘Zona Zone 3’ in regulation classification) Min. desired comfort % (hrs)

Figure 5: Summer indoor ndoor temperatures in techno mud model are considerable lower than those obtained obtaine for the standard model.

35%

Achieved comfort % (hrs)

60%

Elements to watch

Direct solar gains, diurnal variation

Weaknesses

High % of hours above comfort

Strengths

Very low heating load

Further improvements

Summer ventilation, night time ventilation, shading

Table 7: Analysed results for Location 1: Antofagasta (‘Zona 1’ in regulation classification) Min. desired comfort % (hrs)

Figure 6: Results are less successful for techno mud during the coldest week, although there is some improvement.

42%

Achieved comfort % (hrs)

66%

Elements to watch

Direct solar gains

Weaknesses

High % of hours above comfort

Strengths

No heating loads

Further improvements

Ventilation, shading

Table 8: Analysed results for Location 2: Concepcion (‘Zona 4’ in regulation classification) Min. desired comfort % (hrs)

Figure 7: In colder locations, summer indoor temperatures in techno mud building are also lower, although the

34%

Achieved comfort % (hrs)

52%

Elements to watch

Direct solar gains and heat losses.

Weaknesses

High heating loads

Strengths

Low heating load

Further improvements

Insulation, solar gains optimization

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 9: Analysed results for Location 3: Punta Arenas (‘Zona 7’ in regulation classification) Min. desired comfort % (hrs)

33%

Achieved comfort % (hrs)

36%

Elements to watch

Heat losses and cold winds.

Weaknesses

Very high heating loads

Strengths

No apparent strengths

Further improvements

Air tightness and insulation, solar gains optimization

5. CONCLUSIONS When analyzing the results obtained from all the different models, this study took two different approaches, both in regards to thermal comfort ranges, and concentrating on the indoor temperatures achieved. One of the analyses took a standard approach, where minimum and maximum indoor operative temperatures were set as the lower and higher limits for a comfort neutrality zone, and remained stable throughout all locations and models. Under this perspective, most of the techno-mud models proved to be up to the required minimum standards of comfort when compared to a Chilean Thermal Regulation compliant model. They also improved performance by reducing indoor temperatures and overheating with different levels of success. The main issue remaining to be solved when applying these comfort parameters is related to the temperatures below the comfort range, and the heating loads resulting from this especially during the winter months. Further testing is needed to verify whether these issues can be improved by additional passive strategies. A second analysis was undertaken, this time considering the adaptive comfort approach, where the comfort range depends on the location. In this scenario, the techno-mud buildings managed not only to match the minimum standards set by the Chilean Thermal Regulation compliant model, but to improve results. Here, because the comfort ranges allow lower temperatures within the comfort neutrality zone, the heating loads are considerably reduced, changing the focus of issues remaining to be solved. In this case, the main concern lies with the temperatures above the comfort range, and the resulting cooling loads at different times of the year. Because the models used in this study are generic models which do not take into account any other passive strategies, it is highly likely that if appropriate passive strategies such as natural ventilation, night time cooling, daylight management etc, are applied to the models, the cooling loads could potentially be substantially reduced, improving overall performance. This study proves that ‘techno-mud’ has a much wider application potential in the building industry in Chile. The relatively low tech building technique, low material and building cost and potentially shorter construction time would make this material a good alternative and sustainable building

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material alongside the usual building materials like concrete and brick.

6. ACKNOWLEDGEMENTS Special thanks to ‘Sur Tierra Arquitectura’, for providing the raw material with which this research was possible and to architect Pablo Alvear, who provided a permanent link to the architectural practice.

7. REFERENCES [1] Ronald Rael, Earth Architecture, 1st ed. (Princeton Architectural Press, 2008). [2] Gernot Minke, Building with Earth: Design and Technology of a Sustainable Architecture, 1st ed. (Birkhäuser Basel, 2006). [3] www.iconstruccion.cl/mart [4] José Pablo Arellano, Políticas Sociales Y Desarrollo: Chile 1924-1984, ed. Corporación de Investigaciones Económicas para América (Santiago, Chile: CIEPLAN, 1985). [5] www.bcentral.cl/prensa/resumenestudios/dtbc365.htm [6] Ernst Muller, Proc. IV Congreso Nacional de ENergia COCIM, Valparaiso – Chile (2000). [7] Ernst Muller, Proc. VII Encontro Nacional sobre Conforto no Ambiente Construido (ENCAC), Curitiba, PR - Brasil (2003) [8] /www.ine.cl/canales/chile_estadistico/estadistica s_sociales_culturales/est_sociales_culturales.ph p [9] Gernot Minke, Building with Earth: Design and Technology of a Sustainable Architecture, 1st ed. (Birkhäuser Basel, 2006). [10] /www.ine.cl/canales/chile_estadistico/estadistica s_sociales_culturales/est_sociales_culturales.ph p [11] J. F. Nicol and M. A. Humphreys, Energy and Buildings 34, no. 6 (July 2002): 563-572. [12] EnergyPlus Energy Simulation Software by the U.S. Department of Energy. [13] Chartered Institution of Building Services Engineers CIBSE, Environmental Design: CIBSE Guide A, 7th ed. (London: CIBSE, 2006). [14] Ibid.

MATERIAL (ENVIRONMENTAL AND HEALTH ASPECTS) / WASTE MANAGEMENT

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

[1] Gernot Minke, Building with Earth: Design and Technology of a Sustainable Architecture, 1st ed. (Birkhäuser Basel, 2006). [2] www.iconstruccion.cl/mart/ [3] José Pablo Arellano, Políticas Sociales Y Desarrollo: Chile 1924-1984, ed. Corporación de Investigaciones Económicas para América (Santiago, Chile: CIEPLAN, 1985). [4] www.bcentral.cl/prensa/resumenestudios/dtbc365.htm. [5] Ernst Muller, “Estudios parametricos con simulaciones termicas para viviendas con climatizacion pasiva en la zona central de Chile.,” in (presented at the IV Congreso Nacional de Energia COCIM, CONAE 2000, Universidad Tecnica Federico Santa Maria, Valparaiso, Chile: IV Congreso Nacional de Energia COCIM, CONAE 2000, 2000). [6] Ernst Muller, “Analise e propostas de desenho passivo para edificacoes habitacionais na zona central do Chile,” in (presented at the VII Encontro Nacional sobre Conforto no Ambiente Construido (ENCAC), Curitiba, PR - Brasil, 2003). [7] www.ine.cl/canales/chile_estadistico/estadisticas _sociales_culturales/est_sociales_culturales.php [Accessed August 18, 2009]. [8] Gernot Minke, Building with Earth: Design and Technology of a Sustainable Architecture, 1st ed. (Birkhäuser Basel, 2006). 10

[9] J. F. Nicol and M. A. Humphreys, “Adaptive thermal comfort and sustainable thermal standards for buildings,” Energy and Buildings 34, no. 6 (July 2002): 563-572. [10] EnergyPlus Energy Simulation Software by the U.S. Department of Energy. [11] Chartered Institution of Building Services Engineers CIBSE, Environmental Design: CIBSE Guide A, 7th ed. (London: CIBSE, 2006). [12] Ibid.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The Representative Day Technique in the Analysis of Thermal Comfort in Outdoor Urban Spaces Roberta COCCI GRIFONI1, Giovanni LATINI2, Simone TASCINI1 1

School of Architecture and Design, Camerino University, Ascoli Piceno, Italy 2 Marche Polytechnic University, Ancona, Italy.

ABSTRACT: The aim of this study is to evaluate the possibility of assessing the diurnal variation of PMV thermal comfort index by introducing the Representative Day technique in order to obtain information on correlation between thermal comfort and meteorological parameters. The representative day is constituted by the actual data of the day, in the considered period, where the sum of the mean-square differences among its evaluated or monitored quantities, averaged within each hour, and the same quantities for all other days at the same hour is minimised. This technique can prove to be a very important tool for identifying both anomalous and standard behaviours of comfort indices within the selected period in outdoor urban spaces. In this paper a preliminary evaluation of the methodology for the representative day of PMV index is presented. Keywords: Thermal, comfort, least representative day, representative day, PMV

1. INTRODUCTION Thermal comfort is often faced with the task of using large amounts of data that yields meaningful information concerning the thermal sensation. In fact, thermal perceptions and preferences of individuals outdoors cannot be entirely explained by the energy balance of the human body. They are also affected by psychological and behavioural factors or the socalled thermal adaptation. To examine the effect of thermal adaptation on seasonal outdoor thermal comfort, a lot of interviews with concurrent micrometeorological measurements are usually conducted. It is possible to present the data concisely and meaningfully using certain procedures, without displaying the values for each observation taken from the population. Once, meteorological and thermal comfort data have been collected it is essential to interpret these data correctly. In particular, it is important to interpret data by using appropriate statistical analysis and the analysis of thermal comfort presupposes a synthesis of information derived from temporal data series. It is important to deal with realistic data and an actual day should be considered, but the widely used typical day is not an actual day. In a typical day hourly meteorological data are generally obtained by means of temporal averages. A temporal average is operated over data acquired at the same hour of each day belonging to the entire period considered. It allows the assessment of the daily oscillations of the monitored quantities. An alternative to the typical day is the representative day. In this paper a preliminary evaluation of the methodology for the representative day in order to evaluate the thermal sensation is presented. A large data base has been considered for the evaluation in a complex coastal area, namely Ascoli Piceno which is an interesting city in a central region of Italy (Marche) comprising valleys, hills, urban and industrial zones. Results, in terms of monitored

quantities obtained applying both approaches, have been compared showing good agreement. The representative day allows to appreciate daily variations of comfort condition but it is a real day, a characteristic not retained by the typical day.

2. THE REPRESENTATIVE DAY The representative day RD [1] is constituted by the actual data of the day, in the considered period, where the sum of the mean-square differences between its estimated quantities, averaged within each hour, and the same quantities for all other days at the same hour is minimised. In fact the main advantage of the representative day, compared to the typical day, is that it is an actual day, identified by a precise date. This allows the identification of the associated meteorological parameters, and the definition of thermal comfort characteristics. The representative day is a daily data set, which is characterised by the least differences with respect to all the 24-hour estimations of the considered temporal series. In general it is used the typical day (TD) but it could be defined as a “fictional” day, whose hourly values are given by the parameter means, calculated, hour-by-hour, over all the days of the period of study. The period may be a month, season, year, or grouping of particular days that share the features one wishes to study. However, since the TD is not a real day, this form of evaluation provides a presentation averaged over the hourly trend, which cannot take account of the variations characterising the actual behaviour of the quantity under examination. The TD can be considered as an extreme case: for an infinite series of data, the RD tends toward the TD. Therefore, the TD can be considered an asymptotic limit for the RD. This technique can prove to be a very important tool for identifying both anomalous and standard behaviours of thermal comfort within the selected period and establishing measures of assessment and control. The least square matrix can be written as:

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Aij = ∑ ( cki − ckj ) 24

2

i,j = 1,2...N (1)

k =1

where N is the number of days in the time period for which the representative day is calculated and cki is the comfort parameter of the i-th day at the k-th hour. Ai indicates the sum of all the squared residuals of the i-th line (or column, Aij being a symmetrical matrix with all zeros in the main diagonal):

 N  Ai =  ∑ Aij   j =1 

(2) The representative day (RD) is the one with the lowest sum, i.e. the i-th day where Ai is the smallest of the quantities obtained: min(Ai) ⇒ RD (3) The introduced methodology allows the evaluation of the “least representative day” (LRD), that is the day which maximises the sum of squared residuals: max (Ai) ⇒ LRD (4) In this study the least representative day can correspond to an anomalous situation of thermal sensation. 2.1. The representative Index The “representativity” of a representative day can be mathematically expressed by the adimensional index (DI): N

DI =

24

∑∑ (Γ

k

− cik )

∑∑ (c

k

− cik

i =1 k =1 N

24

i =1 k =1

where

ck

2

)

2

(5)

is the mean hourly value of the typical

Γ

k is the mean hourly day at the k-th hour and parameter of the representative day at the k-th hour. It is an adimensional quantity that is closer to unity for the most representative day of the observed period. When DI is equal to 1, this value denotes that the most representative day coincides with the typical day. In the same way the least representative day can also be normalised, but the value of DI will be greater than 1, showing the low degree of representativity of the estimated day.

3. THERMAL COMFORT 3.1. Urban Comfort and thermal indices Human thermal comfort is defined by ASHRAE (American Society of Heating, Refrigerating and Air Conditioning Engineers INC) as the state of mind that expresses satisfaction with the surrounding living or working environment. Since the 1960s, heat-balance models of the human body are accepted in the assessment of thermal comfort. The basis for these models is the

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COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

energy balance equation for the human body (6) which describes energy flows body/environment: (6) M + W + R + C + ED + ERD + ESW + S = 0 Where, M: the metabolic rate (internal energy production), W: the physical work output, R: the net radiation of the body, C: the convective heat flow, ED: the latent heat flow to evaporate water diffusing through the skin (imperceptible perspiration), ERD: the sum of heat flows for heating and humidifying the inspired air, ESw: the heat flow due to evaporation of sweat, S: the storage heat flow for heating or cooling the body mass. The differences between the various existing models are attributable to the complementary parameterizations related to personal data required to solve eq.6. In the last years many outdoor climatic and comfort indexes have been elaborated; one of the first and still very popular heat-balance models is the comfort equation defined by Fanger [2]. In this paper the widely used biometeorological index, PMV (Predicted Mean Vote) was selected. It is an objective measure of the thermal comfort sensation, and Fanger [2] derived this indicator from an indoor-use comfort model based on his investigations on the thermal comfort of over 1000 people in an artificial climate chamber, where several climate parameters as well as human clothing and activity could independently be varied [3]. PMV predicts how a large sample of human beings would characterise their comfort sensation according to the meteorological environment, the level of their activity and their clothing using the values of the originally seven-point (from –3 to +3) ASHRAE comfort scale (Table 1). This comfort scale at around 0 is characterized as comfortable, higher and lower values indicate increasing probability of thermal discomfort as well as stress due to heat and cold conditions, respectively. In (extreme) real weather conditions, PMV can be higher than +3 or lower than –3 [4]. Table 1: Valuation scale of the thermal environment

-1

Evaluation Thermal Environment Hot Worm Slightly warm Acceptable thermal condition Comfortable Acceptable thermal condition Cool

-2 -3

Cold Extremely cold

PMV +3 +2 +1 +0.85 -0.5
PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

One of the recently used bioclimatical model is the RayMan model, which is well-suited to calculate radiation fluxes because it considers more precisely the effect of a complex urban structure [5]. Among others a final output of the model is in polar coordinates about the area including the sun path of the observation day at the place, with the shadow of buildings, trees, or other obstacles and sky view factor. All the evaluations of PMV were performed with this model. 3.2. The case study area All the evaluations are carried out for Ascoli Piceno in the Marche region, a location in central Italy at 42°, 50’N, 13°, 37’E and 154 above sea leve l (Fig. 1). The Marche climate is categorised as Mediterranean, with hot and humid summers and cool winters.

investigation was performed in the summer of 2008. In the summer 2008 the mean daily temperature anomalies showed a generally accentuated warming with respect to the average conditions of July and August, according to the series data 1971-2000. The portion of the region that suffered the main warming was the Adriatic seaside, particularly the coasts of medium-lower Adriatic Sea, where the daily temperature anomalies reached also the values of +6-7°C with respect to the mean values of the perio d. Ascoli Piceno is a medieval town laying at the confluence of Tronto River with Castellano Creek, surrounded by mountains on three sides. The study area is a central city zone, precisely a redevelopment area where a carbon and graphite industry was formerly located. The domain simulated is made of two long buildings (270 m and 240 m) with height of 15m, separated by a large square of a constant width of 100 m (Fig.2) .

Figure 2: aerial photography of the area study

3.3. Rayman Model

Figure 1: location of Ascoli Piceno town in Italy.

During the typical summer months (beginning in May and continuing through September) the air temperature (Ta) can reach 38 Celsius degrees and the daily Ta amplitude can be relatively wide. The atmospheric moisture content sometimes reaches very high levels (RH = 70%). On the contrary, winters are short and cold, especially at night (reaching freezing point). The living conditions during summer periods are becoming very difficult because of higher summer temperatures in recent years. Weather data from meteorological stations belonging to ASSAM (Agenzia Servizi Settore Agroalimentare Marche) have been used to obtain daily and monthly mean values of summer months of the main meteorological parameters to compare with climatic values referred to the period 1971-2000. The

The evaluation of the thermal comfort condition can be objectified and quantified using integrated index that consider the micro climatic environment parameters and the work-related energy metabolic expenditure MET, and the typology of clothing (thermal insulation CLO) commonly used. Among these indexes, the most precise one reflecting the influence of the above mentioned physical and physiological variables on thermal comfort is PMV (Predicted Mean Vote). Synthetically, it comes from the equation of the thermal balance whose result is compared to a scale of psycho - physical health and expresses the average opinion (average foreseen vote) about the thermal sensations of a group of subjects The model RayMan [6], used to estimate PMV values, estimates the radiation fluxes and the effects of clouds and solid obstacles on short wave radiation fluxes. The final output of this model is the calculated mean radiant temperature, which is required in the

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

energy balance model for humans and the Predicted Mean Vote (PMV) that is also required for the assessment of urban bioclimate. Rayman model a versatile tool to simulate numerically thermal comfort indices. It can be used at points where data related to the radiation environment, like shapes of surround buildings and meteorological parameters, is available to input into the model (Fig.3).

Figure4: Representative day (RD,24 August), least representative day (LRD,30 August) and typical day (TD) of PMV during August 2008

Figure3: main window of Rayman

4. DATA ANALYSIS In order to evaluate the usefulness of the Representative Day technique, summer monthly periods were analysed over nine years (2001-2009). The relative investigations have been often further complicated by gaps in data series and, more in general, by the huge mass of data to be processed. Typical day, representative day and least representative day have been valuated and while the typical and representative day proceed in the same way, the least representative day shows different trend for the PMV thermal comfort index. The possibility of studying a few, rather paradigmatic scenarios, suggestive of singular or standard conditions, would be of considerable help, at least in reducing the amount of data needed to shape up the study of the actual scenarios. The calculated PMV indices and meteorological data measured during July and August 2008 have been employed as an example of application. Figures 4 and 5 show the data related to PMV thermal comfort index:

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Figure5: Representative day (RD, 25 July), least representative day (LRD, 15 July) and typical day (TD) of PMV during July2008

In both cases (Fig.4, Fig.5) the representative day (RD) and the typical day (TD) present the same course. Examining graphical representation of the least representative day (LRD), we can notice that PMV shows the same trend of the typical and representative day, although with higher values of comfort index in the central part of the day. Combining meteorological data and thermal comfort indices (PMV) we can observe that in August month the least representative day is the warmer day ( see figures 6 and 7) during the analysis period.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure6: Temperature behaviour during August 2008

Figure6: Temperature behaviour on 30 August 2008

6. REFERENCES [1] Tirabassi T., Nassetti S., Short Communication: The representative day, Atmos. Environ., 33, (1999), 2427. [2] Fanger, P.O. Thermal comfort. McGraw-Hill, New York , (1972) [3] Höppe P Heat balance modelling. Experientia 49, (1993), 741. [4] Mayer H, Höppe P. Thermal comfort of man in different urban environments. Theor Appl Climatol, 38, (1987), 43. [5] Matzarakis, A.Validation of modelled mean radiant temperature within urban stuctures. AMS Symposium on Urban Environment, Norfolk, USA, (2002), 7.3. [6] Matzarakis, A., Rutz, F., Mayer, H. Proc. of PLEA, Modeling the thermal bioclimate in urban areas with the RayMan model, (2006), 449.

5. CONCLUSION Due to the difficulty of controlling the outdoor thermal environment, it is important to provide thermal comfortable condition which meet occupants’ expectation. Thermal comfort data are a series of measurements of meteorological parameters and thermal indices taken continuously or intermittently, and they may have been collected over a short or long period of time. The procedures required for summarizing and analysing the data may be represented by an estimate of the representative day. The absolute advantage of the representative day method is that it is constituted by the data of an actual day, belonging to the considered period. A preliminary evaluation of the methodology for the representative day and the least representative day for predicted mean vote (PMV) has been presented in an urban area. The good agreement between the representative and the typical day is a further indication that the representative day should be preferred to interpret thermal comfort behaviour.

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An optimized model for a thermally comfortable Dutch urban square Sanda Lenzholzer Wageningen University, chair group landscape architecture

ABSTRACT: Is there a model for a thermally comfortable mid-sized urban square in the Dutch climate context which offers sufficient wind protection and a good distribution of sun- and shade places? To answer this question, a ‘research by design’ process was followed. This process included the design of different alternatives of spatial configurations that were expected to generate thermal comfort in different seasons. These configurations were then tested with Envi-met® simulations on their effects for different seasons and different squares. The ‘research by design’ process showed that for the Dutch context of mid- sized urban squares the most optimal model that could be developed and tested, were sequences of ‘urban shelterbelts’. These consist of 25 m high deciduous trees and have transparent wind screens in the trunk space. The ‘urban shelterbelts’, when placed perpendicular to the dominant Southwesterly winds both protect the squares from these winds and also offer sufficient shaded situations. This optimized model can be used to address thermal comfort in urban square design, but it needs to be adjusted to each place and embedded in the integral design of a square. Keywords: urban squares, outdoor comfort, ’research by design’

1. INTRODUCTION AND OVERVIEW Microclimate- ignorant design of public squares is problematic. This is, amongst other reasons, caused by the lack of knowledge about microclimate responsive design amongst urban designers [1, 2]. A way to make climate knowledge more accessible, is the generation of easy to use design guidelines. In order to create such design guidelines, it is often helpful to use a ‘research by design’ process. ‘Research by design’ is understood “as the development of knowledge by designing, studying the effects of this design, changing the design itself or its context, and studying the effects of the transformations. The ‘TOTE model’ from systems analysis may be recognized in this: Test→ Operate→ Test→ Exit.” [3] . Therefore- similar to the methods used in engineering or in R&D, design alternatives are developed and then tested through simulations of the future situation. The alternatives that score most optimal can be considered as design guidelines [4]. This paper describes the path of generating such spatial patterns for climate- responsive design and testing of these patterns on their effects. Firstly, I specify the underlying typical Dutch climate situations for outdoor sojourn. These form a framework for the climate design proposals as well as a basis for the microclimate simulations. Secondly, I outline the relevant scientific microclimate knowledge for generating patterns that are expected to improve microclimate on Dutch squares. Eventually, I describe the design process which was done for two different case- squares, the Spuiplein in The Hague and the Grote Markt in Groningen, both located in the Netherlands. From this, I draw conclusions on optimized models for microclimate responsive design of Dutch squares.

2. RELEVANT SITUATIONS

DUTCH

CLIMATE

The main climate situations that have to be addressed in outdoor space design are described in this section. This includes design for different seasons and respecting people’s perception of microclimate. Earlier research has shown that microclimate perception relates to the more salient or extreme situations [5] . This mainly concerned wind problems because these situations come about more often in the Dutch situation. Apart from that we can expect that more heat waves will occur in the future and that also these will affect people’s long-term microclimate perceptions. Deduced from that, I assume that hot situations will become salient in the future as well. Hence, the two situations ‘windy’ and ‘hot’ form the starting point for the analysis of situations relevant for thermal comfort in outdoor spaces. These two quite contrary situations and their impact on the two squares in Den Haag and Groningen were simulated in the microclimate simulation software ENVI-met® for the existing situation of the square’s spatial settings. The climate data used were based on the average data from the Royal Dutch Climate Institute KNMI for the weather stations close to the respective cities (see windroses and temperatures in [6]). The first input dataset described a ‘windy’ day is a typical day at the beginning or end of the outdoor seasons, when stronger winds occur and the sun altitude is lower. In this case the 15th of November was chosen because around that time longer shadows occur than at the beginning of the outdoor season. For the wind situation a typical (and in the Netherlands predominant) cyclonic climate situation is chosen with the prevailing wind direction Southwest. These

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Southwest winds are generally stronger than from other directions [7]. The entire set of simulation input data for the windy situation can be seen in “input data windy” and the simulations of the existing situation on maps “existsit-sims” on the website [8]. The second input dataset represented a day within a heat wave in summer where the impact of the direct sun radiation and heat emission from the environment can be problematic. The day chosen was 21st of June because it is the longest day of the year and it is also the day with the shortest shadow patterns. For the wind situation a typical anticyclonic weather situation was chosen with the rather soft Easterly winds that are typical for these situations. The entire set of simulation input data for this situation can be seen in “input data hot” and the simulations of the existing situation on maps “existsitsims” on the website [8].

3. SCIENTIFIC KNOWLEDGE BASIS FOR MICROCLIMATE COMFORT PATTERNS To generate preliminary patterns for thermal comfort in Dutch squares, the microclimate literature was consulted. The factors that can actually be influenced by smaller scale urban design are wind and mean radiant temperature [9]. In a coastal country like The Netherlands wind speeds are generally higher and in the Dutch climate, wind protection can help significantly to achieve better thermal comfort in outdoor places. This wind protection is most effective when it buffers the strong and predominant South Westerlies. In order to generate simple patterns for wind protection elements, basic quantitative knowledge was used to specify the cavity and wake areas around wind shelter elements. The most common general guideline is based on Nägeli [10]. Although also other rules of thumb were developed later that are partly conflicting with Nägeli’s, this rule is most often cited in the literature. Because of that, I used Nägeli’s rule. It describes the general effects of wind screening objects with different densities on the size of the sheltered area at the leeside, depending on the height of the screening objects. This rule of thumb concerns obstacles that are at least 12 times as long as their height (see fig. 1).

nowadays easily be simulated in 3D- design software and therefore SketchUp shadow simulations were used as a tool in this research by design to conduct first studies on sun and shadow patterns.

4. PRELIMINARY SPATIAL PATTERNS FOR MICROCLIMATE COMFORT I translated the requirements for optimized sunand shadow situations and wind adaptation into spatial patterns by making desk-estimations based on the rules of thumb on wind shelter discussed above and through SketchUp shadow simulations. Here, certain options that would not be viable in public square design practice, like too dense covering by pergolas, roofs, trees or other objects were avoided. Microclimate adaptation elements also must not subdivide the place too much on eye- level because that can negatively influence the feeling of safety. The patterns I considered most appropriate are described in the following. 4.1 Generation of preliminary patterns for wind protection For the ‘windy’ day simulated for the two squares it became apparent that the wind speeds in the central areas of the squares can easily reach 4m/s and higher in the existing situation. In order to create a comfortable situation for sojourn, the wind speed has to be reduced at least 50%. Therefore, wind buffering screens were selected that, when distributed in a proper sequence, are expected to bring wind speed reductions of 50% over the whole area. All of these screens should be directed perpendicular [13] to the South-West in order to block the prevailing (and also strongest) winds in the most efficient way. Since vegetative materials or other permeable elements are more efficient in creating longer wakes [10], I decided to use such permeable elements. The preliminary pattern I considered useful was a 15m tall row of trees with transparent ‘medium dense’ windscreens in the trunk areas. This transparent screen is chosen because it does not hamper the possibility to oversee the square which is important for the public’s feeling of safety. I call this an ‘urban shelterbelt’ (fig. 2).

 

Figure 1: Wind protected area behind a medium- dense obstacle according to Nägeli, adapted from Oke 1987

The most important parameter for the influence of mean radiant temperature is sun and shadow [11,12]. The patterns of sun and shadow can

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Figure 2: principle of the ‘urban shelterbelt’

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

4.2 Generation of preliminary pattern for sun- and shadow comfort People prefer a small- scaled distribution of sunny and shaded areas on the square. This way it is easy to make a choice between sunny or shady places without having to move over long distances. I generated series of shadow simulation patterns for common shading devices that can be placed in many squares without hampering the functions. The elements that were most viable on the squares were mid-sized trees (15 m high and 15 m crown diameter, see fig. 3). This was considered the most suitable preliminary pattern because it suggests to offer benefits throughout the whole outdoor season.

simulations of the existing situation. This is described separately for the alternatives on the website [8]. All the alternatives were assumed to improve thermal comfort. In this testing phase the Predicted Mean Vote (PMV) value became the most important indicator for thermal comfort improvement. This index combines all the important microclimate factors and thus also shows how, for instance, shadow- casting elements have effects on the wind field and how wind- buffering elements also cast shadow. 5.2 Developing and testing alternative 1 The first alternative was derived from the preliminary patterns: a combination of a a medium dense urban shelterbelt of 15 m height and a 40 x 40 m grid of 15 m high shadow trees with open trunk space and a dense crown (fig. 4).

Figure 3 tree- shadow pattern for all outdoor seasons projected in non- shaded areas of a square of 100 x 100 m

These preliminary patterns for wind and shade were combined in the next step and then tested ® further in ENVI-met microclimate simulations.

THE

Figure 4 Alternative 1: urban shelterbelt 15 m high and 40 x 40 m grid 15 m high shadow trees projected on Spuiplein, Den Haag

In this section I document the process of generating and testing climate responsive patterns for Dutch squares of medium to large size. The preliminary patterns described in the preceding subchapter were combined and projected on the squares Spuiplein, Den Haag and the Grote Markt in Groningen. Since the simulation software did not offer possibilities to model the ‘urban shelterbelt’ with its different structures of trees and artificial windscreens, this was substituted with a structure completely consisting of vegetation in the simulation input. The alternatives for new patterns were simulated on their microclimatological effects with the same input data that were used to simulate the existing situation in the squares described earlier. The simulation results of the existing situation and the alternatives were compared for five points in time per day: 9,11,13,15 and 17 hrs. In order to evaluate effects of the new alternatives, simulations of the different alternatives were compared to the

The first patterns were then simulated for their effects on microclimate over whole days in the ‘windy’ and ‘hot’ situation for the two locations in Den Haag and Groningen. The differences in PMV on pedestrian level (1.60 m) can be seen in graphical form and a textual specified discussion on the website [8], posters on “altern1-sims” and table 1 ). From the simulations of this alternative projected on both squares, some conclusions could be drawn which had impact on the development of the second alternative. Concerning the shadow patterns of the trees, the shades in the autumn situation showed unexpectedly low PMV values. This seemed somewhat unrealistic because trees have lost foliage in autumn and thus cast less shadow. Therefore I decided to simulate the trees in a foliated and defoliated state in following alternatives. The wakes of the urban shelterbelt were considerably smaller than expected. This had consequences for the settings in later alternatives. In alternative 1, in both squares the PMV values improved slightly for the entire square and surroundings, when compared to the existing

5. TESTING ALTERNATIVES CASE- SQUARES

ON

5.1 General method

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situation. In the hot situation the PMV values changed up to one PMV unit towards comfortably cooler and in the windy, cooler situation the PMV values changed up to one PMV unit towards comfortably warmer in large areas of the two squares. From the simulations it was not possible to conclude why this general improvement occurs. It seems that this effect is based on the higher roughness in the wind field, as well as the general climate buffering effect of vegetation on air temperature. Since I wanted to find out if this effect of vegetation is important, I developed alternative 2 with more vegetation. 5.3 Developing and testing alternative 2 Due to the simulations for alternative 1 showing that the wind shelter effects of the urban shelterbelt of 15m height were not reaching far enough, in alternative 2 the shelterbelt was heightened to 25m. Also, the shelterbelt was entirely closed as opposed to the first alternative where a shade tree with an uncovered trunk area was inserted (which showed a too strong funneling effect). The shadow effect of trees in alternative 1 during the autumn days was too strong, so more attention was given to the species of trees selected as shadow trees. The selection of species for the shadow trees was now based on the times when foliation starts. Tree species that develop foliage late and cast it early are suitable. In summer the foliage should be as dense as possible for efficient shading and in all other seasons the shade should be as minimal as possible. Tree sorts that have these foliation properties are Acer rubrum, Fraxinus pennsylvatica, Juglans nigra, Liriodendron tulipifera and Tilia cordata [14].

for the autumn situation were adjusted. The shadow trees were given a lower leaf area density (LAD) value of LAD 0.2 and the urban shelterbelt was simulated with slightly more foliage of LAD 0.5, representing a species such as Fagus sylvatica that keeps some foliage over winter and is thus assumed to bring about better wind protection than an entirely bare tree. Since I assumed that the trees have an overall positive effect on PMV I also decided to densify the shadow tree pattern to 25 x 25 m. The effects of the second alternative (25 m high medium dense shelterbelt and 25 x 25 m grid of 15 m high dense trees, fig. 5) were then simulated for microclimate effects over whole days in the ‘windy’ and ‘hot’ situation for the two locations in Den Haag and Groningen. The resulting differences in PMV on pedestrian level can be seen on the website [8], posters on “altern2-sims” and table 2. The results of the simulations for alternative 2 indicated that there was- again- a slight improvement on PMV for the whole square and surroundings, but this was not significantly more than in alternative 1. In the hot situation the PMV values changed up to one PMV unit towards comfortably cooler and in the windy, cooler situation the PMV values changed up to one PMV unit towards comfortably warmer. So the assumption that more trees bring a significant effect for PMV could not be confirmed. Furthermore, the results showed that the effect of shade overruling wind buffering effects of trees was still prominent, even though seasonal differences in leaf densities were now taken into account in the simulations. Also with respect to the wind situation, the weak buffering effects in alternative 1 occurred again in this alternative, showing much shorter wakes than expected. A medium dense shelterbelt of 25 m height still seems not sufficient to keep the wind speeds considerably lower for the entire squares. 5.4 Developing and testing alternative 3

Figure 5 Alternative 2: urban shelterbelt 25 m high and 25 x 25 m grid 15 m high shadow trees projected on Spuiplein, Den Haag

In order to represent the seasonal foliage properties appropriately, the simulation- input data

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In the preceding simulations one important effect occurred between the influence of shade and wind shelter: the shadows of the trees seemed to have such a strong local effect on PMV that they can balance out their own wind buffering effects or the wind buffering effects of other trees. This effect was very evident in the ‘windy autumn day’ situations and especially in the second alternative where significantly more shadow trees were used than in the first alternative. In the cooler seasons, the shadow trees, albeit the fact that they have little foliation, seem to have a strong negative effect on PMV. Therefore, in the third alternative I abolished trees that only serve to cast shadow. For trees that also buffer wind, the situation is different. Their shadows also cause cooler areas in spring and autumn, even though their wind shelter effect might be minimized by the shadow. On the other hand, they also generate wind protected areas that are largely situated in the sun and are therefore much more comfortable in spring and autumn. The earlier simulations showed that the wind buffering effects of the vegetation seemed to have a smaller spatial extension than was expected based

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

on the scientific literature. For example, increasing the height of the urban shelterbelt in the second alternative had rather limited effects, whereas according to the literature a shelterbelt of this height should have been more than sufficient to create a 50% wind reduction for the entire squares. This might have to do with the fact that the shelterbelt had shorter length extensions than 12x h. Therefore, I decided to use several urban shelterbelts in sequence for improvement of the wind situation. The chosen distance between shelterbelts was based on the lower foliage density values during spring and autumn when the wind situation is most problematic. I assumed that a distance of 50 m between the urban shelterbelts, which is only 2 x h of the shelterbelt itself, should offer ample wind protection.

software as well as the inexplicable results of some simulations (see ‘general remarks’ in overview of simulation results, website [8], tables 1-3) I doubt if the simulation tools were sufficiently developed to conduct a more refined research by design. The uncertainties about causes and effects made it increasingly difficult to generate fine-tuned design hypotheses and it was uncertain if the simulations will truthfully predict the effects and verify or falsify the design hypotheses. Therefore, I decided to terminate the process after generating this alternative because it clearly shows better results than the first alternatives and is a very evident improvement compared to the existing situation. Due to these significant improvements it can be called an optimized model for a climate- responsive design of a Dutch square. This pattern with its focus on wind protection is also expected to appeal to people’s spatial microclimate expectations in a positive way. As mentioned earlier, Dutch people’s microclimate perception is mainly focused on wind effects. Hence, in urban design responding to microclimate perception, strong images should be offered that suggest wind protection. This optimized model is expected to offer such cues for windprotection due to the smaller scaled rhythm of spatial enclosure and clear visual suggestion of wind protection by the urban shelterbelts.

6. AN OPTIMIZED MODEL ‘RESEARCH BY DESIGN’

 

Figure 6 Alternative 3: urban shelterbelts 25 m high with 50 m distance projected on Spuiplein, Den Haag

The impacts of the third alternative (25 m high medium dense urban shelterbelt in sequence of 50 m) were then simulated for microclimate effects over whole days in the ‘windy’ and ‘hot’ situation for the two locations in Den Haag and Groningen. The resulting differences in PMV on pedestrian level can be seen on the website [8], posters on “altern3-sims” and table 3. Alternative 3, in comparison to the other two alternatives shows the best effects, but it still could be more optimal. The simulated wind buffering effect was not as strong as expected, but this also might be attributable to the way how the urban shelterbelt was simulated. As mentioned earlier, due to the limitations of the simulation software it had to be substituted with a vegetation element, whereas the actual urban shelterbelt should consist of trees and an artificial transparent wind screen in the trunk space. Considering all the literature consulted (albeit some conflicting assertions), in an area of 2 x h behind a wind screen, the wind protection should be more efficient than the simulations suggest. I could have continued to study and research more fine-tuned options through ‘research by design’. But due to the limitations of the simulation

FROM

The optimized model pattern (alternative 3) can be easily used as a design ‘layer’ for microclimate response in the beginning of the design process. In general, this pattern can be used in all parts of North Western European cities that have similar climate to the Netherlands. It is vital that the model pattern is introduced at the beginning of the design process of a square refurbishment or design of a new square. When this pattern is not included early it will be very difficult to introduce the required structural changes in a later design phase. The model can be compromised with other design requirements (e.g. functions, aesthetics) and offers some flexibility. For example, the urban shelterbelts can be placed on a slightly larger distance from each other or their orientation can be changed with some degrees without losing too much of their effects. When circulation requires this, also some smaller areas can be opened in the shelterbelts. Also, making the transparent wind screens under the trees movable will enable the passage of vehicles (e.g. when a market has to be installed) and slow traffic flows. As long as this urban shelterbelt pattern is not getting entirely disrupted in the integrated practical design process, this pattern will always help to improve the local microclimate. Since this model will get adjusted by ‘carving’ or ‘twisting’, clustering etc. to a site in the further integrated design process, the results will always be site-specific solutions and no square that was designed according to this model will be like the other. Although the generation of such models by ‘research by design’, as shown in this example,

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generally seems a clear and straightforward process, this is often not the case. In this ‘research by design’, for example, the generation of a model with the help of scientific literature was problematic due to conflicting assertions in the scientific literature. For the designer who has not developed this fundamental knowledge it is not possible to make sense of these contradictions. Similarly, ambiguous simulation results make it difficult to generate clear design hypotheses on cause- and effect relations of design interventions. Although simulations can be a very useful tool to predict climate, they are only as precise as their underlying mathematical models and the way how these are integrated in the simulations. Fortunately, simulation tools are in constant development and are calibrated to make better predictions. In the future they will be increasingly useful to be integrated into ‘research by design’ processes. I have shown that a ‘research by design’ process can help to generate optimized design patterns. The optimized climate responsive design model I developed can be helpful for many Dutch square design or refurbishment projects. However, there are also public space design projects where it will not be possible to apply this rather generic pattern or where it has to be compromised to such an extent that it loses its effect. In those cases, small scaled design solutions that are precisely fitted to the place can be useful.

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7. REFERENCES [1] Eliasson, I. (2000). "The use of climate knowledge in urban planning." Landscape and Urban Planning, 48(1-2), pp. 31-44. [2] Katzschner, L. (2006). "Behaviour of People in Open Spaces in Dependence of Thermal Comfort Conditions", R.Compagnon, P. Haefeli, and W. Weber, (eds.), PLEA 2006 - The 23rd Conference on Passive and Low Energy Architecture. City: PLEA, Université de Genève, Haute Ecole Spécialisé de Suisse occidentale: Geneva. [3] de Jong, T. M., and van der Voordt, D. J. M. (2002). "Types of Study by Design", in T. M. de Jong and D. J. M. Van der Voordt, (eds.), Ways to study and research urban, architectural and technical design. Delft: Delft University Press, p. 455) [4] Breen, J. (2002). "Design driven research", in T. M. de Jong and D. J. M. van der Voordt, (eds.), Ways to study and research urban, architectural and technical design. Delft University Press, Delft, pp. 137-146. [5] Lenzholzer, S. (2010). "Engrained experience-a comparison of microclimate perception schemata and microclimate measurements in Dutch urban squares." International Journal of Biometeorology, 54(2), pp. 141-151. [6] www.knmi/klimatologie/normalen19712000/per_station.html [7] www.knmi/kd/normalen19712000/station_gegevens.html [8] https://docs.google.com/leaf?id=0B7o18sRGc11 bNzQ5NmRlYjctYTJmMS00NDQ4LWEyZDktNm UzZWI3YjMxNDEw&hl=en&authkey=CKCyrfAD [9] Brown, R. D., and Gillespie, T. J. (1995). “Microclimatic landscape design : creating thermal comfort and energy efficiency”, New York [etc.]: Wiley, pp. 10, 71 [10] Nägeli, W. (1946). "Weitere Untersuchungen über die Windverhältnisse im Bereich von Windschutzstreifen." Mitteilungen Schweizer. Anstalt Forstliches Versuchswesen (24), pp. 659-737. [11] Brown, R. D., and Gillespie, T. J. (1995). Microclimatic landscape design : creating thermal comfort and energy efficiency, New York [etc.]: Wiley, pp. 112-117, [12] Matzarakis, A. (2001). Die thermische Komponente des Stadtklimas, Habilitationsschrift, Universität Freiburg, Freiburg., p.160-198) [13] Dierickx, W., Gabriels, D., and Cornelis, W. M. (2002). "Wind tunnel study on oblique windscreens." Biosystems Engineering, 82(1), pp. 87-95. [14] Brown, R. D., and Gillespie, T. J. (1995). Microclimatic landscape design : creating thermal comfort and energy efficiency, New York [etc.]: Wiley, p. 116)

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve,

Belgium 2011) PLEA 2011 (July - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. ISBN xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

Exploring outdoor climates and urban design in a historic square in Dublin Ágota SZŰCS1, Gerald MILLS2 1

University College Dublin, School of Geography, Planning and Environmental Policy, Dublin, Ireland

ABSTRACT: Historic places in cities are often preserved during urban renewal schemes, and as such, are designed to encourage public use of the outdoor environment. However, climatic considerations are rarely taken into account and the renewed place may create a visually interesting environment that is unpleasant from a climatic viewpoint. In this study, the microclimate of an open urban square and adjacent waterfront near central Dublin is investigated using computational simulation. The major consideration in this climatic environment is shelter from excessive wind at the level of the pedestrian. The research presented here examines the renewed urban environment to evaluate whether the design promotes outdoor use by examining the wind climatology and associated thermal and mechanical comfort of pedestrians. Keywords: wind comfort, microclimate modelling, ENVI-met, Dublin

2. STUDY AREA

1. INTRODUCTION The Grand Canal Square in Dublin has had a rich history. It is located at the eastern end of the Grand Canal and served as a connector between the canal system and the port of Dublin. The urban fabric of the place consisted of large warehouses and terraced housing that fitted its purpose as a place where goods were moved. It was also, until the middle of the twentieth century, a gas works site. By this time however, the area was in decline, the roles of Dublin Port and the Canals had changed and cleaner forms of energy generation were adopted [1]. The renewal of the site began in late 90‟s and followed a pattern established elsewhere in Europe by placing emphasis on designing an urban „quarter‟ that incorporates commercial, residential and cultural functions. The result is an urban square of extended size surrounded by office buildings, a hotel, apartment blocks and a theatre, situated at the waterfront. The place was created for outdoor use and was designed as an entity (Fig. 1). The research presented here examines the environmental conditions of this new urban space using a simulation model. While the results presented here are preliminary, the project will develop climatologies of urban spaces in Dublin that are designed for outdoor use and evaluate their potential use based on outdoor comfort criteria.

Ireland lies on the very western boundary of Europe, between latitude 51° and 55°N and longitude 5° and 10°W. The two major elements shaping Ireland‟s climate are the proximity of the Atlantic Ocean (and the Gulf Stream) and the westerly atmospheric circulation that ensures Ireland‟s climate is dominated by maritime influences [2]. Ireland‟s climate may be described as middlelatitude, marine west-coast (Cfb according to Köppen‟s classification). It has a mild climate with a small annual temperature range around a mean temperature of 9°C. Precipitation occurs throughout the year with receipt ranging from 800 to 2,800 mm across the country. Mean annual wind speed is -1 consistently high, with mean values of 7 ms in the northwest. The prevailing wind direction is southwesterly, off the Atlantic Ocean. Dublin‟s climate is less windy and wet than the average for Ireland. Although the annual rainfall in Dublin is just 1000mm, it receives this over 150 days as low intensity events [3]. Not surprisingly then, cloud cover is often extensive and annual number of bright sunshine hours is relatively low. Rain and high winds are the two sources of outdoor discomfort in Dublin. The study area, the Grand Canal Square (Fig. 2 and 3) is located on the east side of the city close to the mouth of the Liffey River.

Figure 1: View of Grand Canal Dock Square

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Figure 2: View of Grand Canal Theatre and Square

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The study area is about 250 x 250 m and is comprised of several substantial structures: the Grand Canal Theatre (designed by the architect Daniel Libeskind); a tinted glass office building designed by Duffy Mitchell O‟Donoghue and a luxury hotel designed by Manuel Aires Mateus. The square itself was designed by Martha Swartz. It features a composition of a “red carpet” extending from the theatre into and over the dock on a cantilever-like continuation and a “green carpet” of vegetation crossing it over. The square has granite-paved paths allowing movement in straight line or in sharp angle. Benches provide for visitors places to rest and enjoy the closeness of water.

Figure 2: Arial view of Grand Canal Square (circle) and adjacent study areas (ellipses). 1 - theatre building, 2 hotel, 3 - office building. Source: www.googleearth.com

3. COMFORT IN OUTDOOR LOCATIONS Human biometeorology emphasizes the increasing importance that is placed on environment and human health and to their interrelationships. It is essential to explore these when approaching problems related to decreased use of outdoor spaces [4]. Thermally pleasant and comfortable outdoor spaces noticeably influence the amount and type of human physical activity [5] and creation of comfortable spaces is needed in order to satisfy outdoor recreational users [6]. The way people perceive the thermal environment is related to changes occurring in body temperature due to heat loss or gain. Environmental factors, such as air temperature, radiation, relative humidity and wind velocity effect heat dissipation from the human body. Air temperature and relative humidity can hardly be altered at a great extent by architectural means at an outdoor location. Nevertheless, the effect of radiation and wind velocity can be attenuated or reinforced by man-made structures; however their influence cannot be eliminated. Wind represents one of the chief differences between outdoors and indoors. Even a light wind will exceed the typical intensity of air movement that could be experienced in an indoor environment. Wind exerts two kinds of effect on people: direct effect that is often described as “mechanical” effect of wind force concerning both people and items, such as umbrella, accoutrements, dust etc., and “thermal” effect, the more indirect influence of wind affecting thermal comfort when combined with

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humidity, solar radiation and temperature [7]. Wind can be characterised by both a mean flow and a turbulent component. The standard deviation of wind statistics captures the property of „gustiness‟, which is responsible for many features of wind discomfort, including difficulty in maintaining balance when walking. Other wind effects are dependent on the mean speed, such as the energy expended to move ahead against a strong steady wind [7]. In an Irish context, rain and wind are the two chief environmental factors that affect the most outdoor activity. The former significantly limits the time available for outdoor activity. In fact, there „is no doubt that, in practice, the time lost to informal outdoor recreation due to precipitation is generally appreciably greater than its strict duration. Desire to avoid getting wet will usually cause abandonment of the activity before rain has started, and a delay in quitting shelter until the subsequent cessation of the rain seems well established‟ [8]. There is nothing that design can do to alter the outdoor rainfall environment apart from provided covered walkways and building canopies. However, there are a number of design strategies that can manage the outdoor wind environment and promote the use of outdoor spaces. Regarding the effect of wind in urban spaces, the first events associated with discomfort, i.e. pronounced sensation of wind on the face or hair disturbance occur at wind force 2 and 3 on the Beaufort scale [9]. Experiments carried out in wind tunnel provided basis for establishing wind speed criteria for different types of activity. Not only the threshold wind speed value itself but also the percentage of time during that the threshold value can be exceeded is of importance. Table 1 presents the wind criteria chosen – in terms of average wind speed and gust equivalent mean speed (taking into account the peak fluctuation of the wind) - for three types of activity: walking, standing and sitting. It is based on 20% probability of exceedance [7]. According to this approach, for standing maximum 3.9 m/s, while in case of sitting activity outdoors, 2.6 m/s maximal wind velocity is acceptable. The threshold value for walking is about twice as high as for sitting: 5.4 m/s. Wind speeds exceeding 5.4 m/s are regarded as unsuitable for any outdoor activity. Table 1: Example of simple criteria based on 20% probability of exceedance [6]

Activity Uncomfortable for any activity

Comfortable ranges (m/s) > 5.4

Walking

0 – 5.4

Standing

0 – 3.9

Sitting

0 – 2.6

4. METHODOLOGY 4.1. Background climate As a first approach, wind environment is assessed towards „natural‟ or „background‟ climate characteristics recorded at the closest site collecting

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meteorological data: Dublin Airport. The data have been recorded at 10 meters height, at an open, obstacle-free area and characterise a chosen reference year, 2005. Occurring mean hourly average wind speed data of the chosen reference year have been qualified either unsuitable or suitable for sitting, standing or walking activity according to the presented criteria (Table 1). Table 2 shows that during more than 80% of the reference year - altogether 7448 hours out of 8760 - climatic conditions are suitable for outdoor activity in Dublin. During 1312 hours of the year the wind speed exceeds the 5.4 m/s wind comfort threshold value resulting in excessive wind, unsuitable for any type of outdoor activity. The extent to which built environment modifies microclimate at the selected location has been described in relation to background climate. This method allows demonstrating whether the designed urban setting contributes to the reduction or enhancement of the airflow intensity. The selected location has been tested for four different wind directions (north, east, south, west) with a wind speed of 8 m/s measured at a height of 10 meters. Table 2: Frequency of occurrence of specific wind speed intervals suitable for three types of outdoor activity: sitting, standing and walking

4.2. Computational simulation ENVI-met, a computational fluid dynamics (CFD) model is used to examine the microclimate of the Grand Canal Square and adjacent waterfront. ENVImet is a freely available program developed by Prof. Michael Bruse [10] that simulates airflow (both mean and turbulent characteristics) in a neighbourhood comprised of obstacles in the form of buildings and vegetation. It also simulates energy exchanges occurring at surfaces. The program requires input data that are contained in two files: the area input file and the configuration file. The former consists of a threedimensional grid that is used to outline building, vegetation and ground surfaces. Fig. 3 depicts the Grand Canal Square input area file. Light grey grids represent vegetation (trees and turf), while dark grey grids represent buildings. The water surface of the canal, the paved and asphalted surfaces have also been modelled by ENVI-met (however they are not visible on Fig. 3). The configuration file contains the date, desired time period of study (length of simulated time period), time step, roughness length of the zone and meteorological data related to the simulation, such as wind speed and direction, relative and specific humidity and atmosphere temperature.

Figure 3: Area input file representing the Grand Canal Dock Square and its surroundings

5. RESULTS 5.1. Actual configuration Airflow has been modelled by ENVI-met for four wind directions in the selected area, in order to map airflow patterns facilitating the detection of discomfort due to mechanical nuisance of wind. The results have been presented in terms of outdoor activity type whose practice is associated to the defined wind speed interval. Four points located at the following representative zones of the selected area have been chosen: A – central point located at the „bay‟ of the square, B – viewpoint at the cantilever slab reaching over the canal, C – westerly waterfront, D – northern waterfront. Fig. 4 depicts wind environment in case of northern wind. Light grey colour indicates zones suitable for long term sitting and standing, middle grey those for walking, while dark grey shows locations where average wind speed exceeds 5.4 m/s and makes places unsuitable for the practice of any outdoor activity.

Figure 4: Iso-plates representing wind speed (in m/s) in case of northern wind at pedestrian height

In case of northern wind the square - situated on the leeward side of the hotel building - is protected. So is the northern waterfront area (point D) and the cantilever viewpoint providing sheltered environment suitable for long-term sitting and standing, respectively. In contrast, the west waterfront (point C)

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is exposed to northern wind and generates a wind environment unsuitable for the practice of any longterm outdoor activity (Fig. 4). Street canyons with north-south axis off the main square, and having open ends are also exposed to northern wind that results in high wind speeds and again, a wind environment that impedes any kind of long-term outdoor activity. In addition, these streets get small amount of sunshine since buildings are high compared to the width of the street. Lack of direct solar radiation together with intense airflow leads to unpleasant thermal ambience. Airflow pattern in case of southern wind shows no significant difference regarding the centre of the square and the westerly waterfront (point C). However, southern winds cause the occurrence of high velocities at the viewpoint (point B) annulling in this manner comfort (Fig. 5).

and walking, however northern waterfront (represented by point B) is uncomfortable since exposed to strong wind. The situation is much different in case of eastern wind: the square, the northern waterfront such as the viewpoint (B) are unprotected and swept by strong winds. No practice of long term outdoor activity is facilitated by the wind on the viewpoint; while the square and the northern waterfront remain suitable for walking and standing, respectively (Fig. 7). Western waterfront (point C) is located on the lee side of the residential buildings situated on the other side of the canal which provide shelter. Wind speeds are within a range that is tolerable for sitting and standing.

Figure 7: Iso-plates of wind speed (in m/s) in case of eastern wind at pedestrian height Figure 5: Iso-plates representing wind speed (in m/s) in case of southern wind at pedestrian height

In case of westerly winds the centre and the westerly waterfront points are protected by the theatre and the office blocks. Both points (A and C) situated at the leeward side of the buildings represent areas of moderate airflow where long term seating activity is envisageable (Fig. 6).

The results show that the area of interest is particularly sensitive to wind direction. The viewpoint situated on the cantilever slab, representing the continuity of the path leading to the theatre and „floating‟ over the canal is a specially exposed place where for the tested wind speed in the best case long term standing activity can be envisaged. In contrast, the central zone of the theatre square remains relatively protected in case of all four simulated wind directions and facilitates long-term outdoor activity. The waterfront zones - represented by points C and D - are sensible to wind directions parallel to streets they (point C and D) are aligned with. Table 3 summarizes the type of outdoor activity that can be carried out depending on the wind environment at the investigated locations, in function of wind direction. The waterfront zones - represented by points C and D - are sensible to wind directions parallel to streets they (point C and D) are aligned with. Table 3: Adequate proposed long-term outdoor activity in function of wind environment; UC stands for uncomfortable Point

North

East

South

West

A

sitting

walking

standing

sitting

B

standing

UC

UC

standing

C

UC

standing

UC

sitting

D

sitting

UC

walking

UC

Figure 6: Iso-plates of wind speed (in m/s) in case of westerly wind at pedestrian height

The wind environment at the viewpoint reaching over the canal (point B) remains suitable for standing

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5.2. Introduction of a shelterbelt The existing wind environment of the investigated area presents characteristics that can surprise pedestrians and create unpleasant conditions, such as rapid changes in terms of wind speed within relatively short distances. Existing wind environment can be moderated by means of architecture and landscape design. A first attempt investigating the impact of a shelterbelt comprising four wind screens of dense hedge placed onto the waterfront corner at the junction of the square and a narrow street oriented north-south off the main square. In case of northern wind the area protected by the shelterbelt becomes suitable for long-term sitting and standing including the zone where in the existing configuration excessive wind was frequent: the viewpoint on the cantilever slab „floating‟ over the canal (Fig. 7).

Wind environment at four representative locations situated at the studied area have been presented for four wind directions. The results reveal that airflow characteristics between buildings are strongly related to the morphology, in other terms, the geometrical characteristics of the urban fragment. The microclimate created between the buildings is very sensitive to orientation of streets relative to wind direction, to heights and forms of buildings and also to the distance between buildings. The paper aims to highlight that urban planning has consequence on microclimate, comfort and health of habitants; that is why climatic characteristics should be integral part of the planning process.

7. ACKNOWLEDGEMENTS The research project is financed by the IRCSET – Irish Research Council for Science, Engineering and Technology. The authors express their gratitude to Dr. Bernadett Balázs for her guidance through the familiarization with the program ENVI-met.

8. REFERENCES

Figure 7: Iso-plates of wind speed (in m/s) in case of southern wind - Configuration with shelterbelt.

This example demonstrates that with a relatively small intervention wind environment can significantly be moderated. Further study aims to examine how other areas exposed to intense airflow can be protected by natural or constructed wind screens.

6. CONCLUSION The present example shows how renewed urban structure shapes through its morphological characteristics natural climate, creating conditions that are either uncomfortable or suitable for practice of different outdoor activities. Microclimatic conditions have often not been part of the planning process of public urban spaces, created during urban renewal schemes. These spaces have been created with the aim of encouraging outdoor civic life and activity. Their success is strongly related to climatic conditions experienced in situ by pedestrians. In an Irish context shelter from excessive wind is the principal climatic concern. In consequence, the study focuses on mechanical nuisance associated with wind. Using meteorological data collected at Dublin Airport it has been demonstrated that during the major part of the year wind conditions facilitate long-term outdoor activity at the selected location.

[1] http://www.ddda.ie/ Article online: Grand Canal Square is rapidly becoming the commercial and cultural heart of the area [2] P. K. Rohan, The Climate of Ireland (1975) Dublin, The Stationery Office. [3] http://www.met.ie/climate/ Climate of Ireland [4] J. K. Vanos, J. S. Warland, T. J. Gillespie, N. A. Kenny. Review of the physiology of human thermal comfort while exercising in urban landscapes and implications for bioclimatic design. Int J Biometeorol (2010) 54:319–334 [5] N. Gaitani, G. Mihalakakou, M. Santamouris, On the use of bioclimatic architecture principles in order to improve thermal comfort conditions in outdoor spaces. Build Environ (2007) 42:317– 324 [6] R. D. Brown, T. J. Gillespie, Estimating outdoor thermal comfort using a cylindrical radiation thermometer and an energy budget model. Int J Biometeorol (1986) 30(1):43–52. [7] American Society of Civil Engineers. Task Committee on Outdoor Human Comfort, Outdoor Human Comfort and its Assessment: State of the art (2003) [8] L. S. Leech, A provisional assessment of the recreational quality of weather in summer, in terms of thermal comfort and the adverse effect of rainfall. Irish Meteorological Service Technical Note No. 47 (1985) [9] J. Gandemer, A. Guyot, Intégration du phénomène vent dans la conception du milieu bati. Guide méthodologique et conseils pratiques (1976) [10] M. Bruse, ENVI-met website (2004) Online: http://www.envimet.com

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

THERMAL COMFORT IN URBAN PUBLIC SPACES: CASE STUDIES IN PEDESTRIAN STREETS IN CITIES OF SAO PAULO STATE, BRAZIL

Maria Solange Gurgel de Castro Fontes1, Cristiane Dacanal2, Carolina Lotuffo BuenoBartholomei3, Marialena Nikolopoulou4, Lucila Chebel Labaki5 1

Architecture, Arts and Communication Faculty, University of São Paulo State “Júlio de Mesquita Filho”, Bauru, Brazil 2 Civil and Engineering Faculty, University of de Campinas, Campinas, Brazil 3 Science and Technology Faculty, University of São Paulo State “Júlio de Mesquita Filho”, Presidente Prudente Brazil, 4 Kent School of Architecture, University of Kent, Canterbury, United Kingdom 5 Civil and Engineering Faculty, University of de Campinas, Campinas, Brazil ABSTRACT: This paper is part of a more comprehensive project that aimed to analyze the users' thermal comfort in convivial urban spaces and linear spaces in different cities of Sao Paulo State. The research has the purpose of contributing to advance studies on thermal comfort in those spaces in Brazil, based on the methodology developed by RUROS Project (Rediscovering the Urban Realm and Open Spaces). This paper shows case studies developed in three pedestrian streets located in the cities of Campinas, Bauru and Presidente Prudente. By monitoring the microclimatic variables (air temperature and humidity, air velocity and global solar radiation, simultaneously with structured interviews) it was possible to evaluate the Actual Thermal Comfort (ASV) and the calculated one through PET (Physiological Equivalent Temperature). The results presented different limits for neutral temperature in each one of the evaluated cities. However, 59,5% of the total analysed sample indicated comfort limits ranging from 18 to 26 °C. The results also showed that hot weather conditions are more critical for pedestrians and highlighted the necessity of a requalification of those spaces aiming to improve the microclimatic characteristics and consequently to influence the users´ thermal satisfaction. Keywords: open urban space, thermal comfort, pedestrian streets

1. INTRODUCTION The urban spaces have environmental characteristics that include physical and microclimatic aspects of social significance, they influence the change of human behaviour and can make them more or less attractive. As exposed by Lynch [1], the spaces also gain significance according to the urban context, composed of nodes, edges, paths and landmarks. In general, the nodes or focal points are characterized by human permanence collective activities [2]. The paths or linear spaces have a more fluid function and are characterized by the nonpermanence. Nevertheless, the environmental quality of the public spaces and their localization can transform their use. Thus, the spaces designed for circulation, such as streets and sidewalks, can be transformed in a convivial space. The same way, the spaces without enough environmental qualities can become problematic and subsequently empty urban space [3]. Which characteristics should spaces to walk have, so that they became attractive to the population and were considered safe and pleasant places? The subspace presence, i.e. fewer focal points in the linear spaces, contributes for the transformations in places to visit [4]. The presence of urban furniture (benches, tables, flowerbeds, lamps, among others) is highlighted by the population as well. Apart from

the presence of unusual elements provoking the sense of surprise to the pedestrian, the public spaces have to be attractive in their boundaries (walls, buildings and shorelines), because it is through it that it is possible to access other activities [2]. The best examples are the pedestrian streets limited by commercial, services or historical buildings. The focal spaces, which acquired use of nonpermanence, link the activities of the boundaries. Good examples are the squares in central area that have bus or subway stations. The success of the linear spaces chosen to be pedestrian routes is in its microclimate. The pedestrian prefers shade and nice temperature in hot climate. Therefore, the presence of trees, marquises and covered porticos are favorable to thermal comfort. Regarding the microclimates, it is important to emphasize that they are influenced by open space layouts, vegetation and green surfaces in general, water presence and material surfaces. Microclimates are also affected by wind exposition, which is the main regulator of humidity and thermal sensation among others. For this reason, the special typology, the presence of various vegetation strata (grass, bushes and trees) and material characteristics can be decisive in urban public space quality and consequently in users thermal satisfaction, determinative factor for the use and local time permanence.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Evaluating comfort in open public spaces is a complex subject and the inter-relation between numerous and different parameters are necessary. Even though the microclimatic parameters greatly affect the comfort sensation, they are not the only determinatives to evaluate the thermal environment [5]. The existent difference between users` comfort sensation (Actual Sensation Votes-ASV) [6] and the calculated one (Physiological Equivalent Temperature - PET) [7] is related to the great influence of psychological adaptation over the comfort state, which involves the naturalness, thermal expectation, thermal experience, memory, physiological acclimatization, possibilities of sun or shade exposition and environmental stimulus [8]. Aiming to characterize public linear spaces and verify how the environmental physical aspects interfere in the microclimate, in the pedestrian thermal comfort (according to PET et index and ASV) and in the use and appropriation of space, this research presents case studies in cities of the State of Sao Paulo, Brazil. The methodology was based on RUROS Project - Rediscovering the Urban Realm and Open Space [6]. For such, two linear spaces (pedestrian streets) and a punctual space, which has a function of crossing space (linear space) with physical characteristics and diverse microclimates, were chosen.

2. CASE STUDIES The public linear spaces researched took place in three cities of the state of São Paulo, Brazil – Campinas (latitude 22º 48’ South and longitude 47º 03’ West), Bauru (latitude 22º21’ South and longitude 49º01’ West) and Presidente Prudente (latitude 22°07' South and longitude 51°23' West). The three cities are characterized by cool and dry winter and hot and humid summer. The spaces evaluated are located in the downtown area of those cities. It is observed that the pedestrian route in urban centers is associated with the presence of commerce, services and public transport. Therefore, those areas are characterized by intense pedestrian flux and many times they are in conflict with vehicle traffic. They are densely populated regions, with tall buildings, predominantly of commercial use. In Campinas the research was performed in “Largo do Pará” (Fig. 1), a punctual space which service as linear space and which has permanence subspace. The square, located on one of the main avenues of the city, “Francisco Glicério” avenue, has historical and cultural value and was established in the middle of the nineteenth Century, gaining the status of public urban space at the end of that same century. During its many celebrations, it received some equipments – bandstand, water-fountain, coffee monument, among others. Its memorable value motivated its registration as “national asset” in 2008. Its most important functions are associated with the presence of public transport (regional and municipal buses) and taxi and the presence of hotels and commerce in the neighborhood. The square has

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equipment such as playground, fast food commerce and newsstand. “Largo do Pará” square is surrounded by buildings of 2 up to 10 floors, painted in different colors (the paint is faded). Its pavement is made of black and white stones known as “Portuguese stone”. The gardens are well defined, with several plant species of different sizes. The benches are made of wood and cast iron. The fountain and other urban furniture are built in concrete, masonry and cast iron. The playground is surrounded by an iron fence, its equipment is made of wood and its ground covered with sand. In Bauru the study took place on “Batista de Carvalho” pedestrian street mall (Fig. 2). That street has a significant historical importance, for it used to be the entrance gate for the passengers who disembarked at “Noroeste do Brasil” Railway Station. After the decline of the rail transport in Brazil, the street, which connects “Machado de Melo” square to “Rui Barbosa” square, became an attraction point for commerce, achieving regional impact. In 1992 the street became pedestrian restrict use, time when public equipments were implanted such as benches, garbage bins, lamps, porticos, among others. The commercial buildings in brick masonry, each painted in different colors, are usually of two and three floors and the pavement is made of Portuguese stone in white and black interpolated with concrete strips. The urban furniture is made of wood and concrete (benches and flowerbeds) and the porticos are of metallic structure. Some porticos have transparent polycarbonate shelter in blue.

Figure 1: Focal space “Largo do Pará” that work like a linear space – Campinas. Source: Google Earth.

Figure 2: Pedestrian street “Batista de Carvalho” – Bauru. Source: Google Earth.

In Presidente Prudente the study took place on “Nicolau Maffei” pedestrian street (Fig.3). The

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

pedestrian exclusive use occurred in the beginning of the 80`s in the downtown area. There is an intense flux of pedestrians of different ages, especially adults, who make use of commerce, banks services in the area or just as a passage to perform other activities. Apart from the existing commerce shops there is also the presence of shadow economy commerce. The urban equipments implanted on the pedestrian street are: benches, public phone booths, garbage bins, flowerbeds and tables and chairs of the food shops. This pedestrian street, shaded by two storied buildings and trees, is also paved with white and black Portuguese stones. The benches and flowerbeds are made of concrete and wood and the buildings of brick masonry with façades painted in different colors.

Figure 5: Monitoring points (1, 2 and 3) in Bauru and solar chart overlapped on fisheye photos (SVF: P1 = 0,403, P2 = 0,259 and P3= 0,313) Figure 3: Pedestrian street “ Nicolau Maffei” – Presidente Prudente. Source: Google Earth.

In general the analyzed public spaces have a characteristic in common - the Portuguese stones used for pavement. In Brazil those stones, which have in their composition limestone and basalt (thermal conductivity of 1,6 and 2,9 W/m.K), are widely used for pavement in public squares and pedestrian streets, due to their flexibility in composition. Concrete and wood are also widely used materials, especially in urban furniture. The characteristic of the materials used in the surrounding buildings are similar as well (thermal conductivity between 0,70-1,05 W/m.K) and the façades are painted of varied colors (absorptance between 0,20 and 0,97 and emissivity of 0,9). Figures 4, 5 and 6 present images of the analyzed public spaces and the solar chart overlapped on hemispherical photographs in each data monitoring local. These images show the urban geometry (in each one of them) and urban arborization influence (in Campinas and Presidente Prudente) in the Sky View Factor (SVF) and consequently at periods of direct solar radiation incidence during the year. Figure 6: Monitoring points (1, 2 and 3) in Presidente Prudente and solar chart overlapped on fisheye photos (SVF: P1 = 0.152, P2 = 0,248 and P3 = 0,150)

3. METHODOLOGY Figure 4: Monitoring point in Campinas and solar chart overlapped on fisheye photo (SVF = 0,245)

The investigation about the thermal comfort conditions in 3 pedestrian streets in the cities of Campinas, Bauru and Presidente Prudente, located

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

in Sao Paulo State, Brazil, was conducted in different weather conditions (cool and dry, hot and dry and hot and humid), during 6 days in each one of the cities, in the period of September 2008 until March 2009. These cities are characterized by cool and dry winter and hot and humid summer. Microclimatic data (air and global temperature, air humidity, global solar radiation and air velocity) were collected with the mobile meteorological station (fig. 7), developed by the Applied Physics and Environmental Comfort Laboratory from UNICAMP (University of Campinas-SP). Simultaneously with the acquisition of the microclimatic data, questionnaires were applied randomly to the users of the spaces in order to identify their profile and thermal sensation (Actual comfort). Issues affecting the use of space (usage patterns, preferences within the area, among others), and the frequency of use were also investigated. The preparation of the questionnaire was based on the RUROS Project [6]. 1.Temperature sensor to globe thermometer; 2.Datalogger to register temperature and humidity; 3. Anemometer Omni directional; 4.Net Radiômetro (piranometer and pirgeometer); 5.Datalogger (Campbell Scientific / CR1000) Figure 7: Photo of the mobile meteorological station

The microclimatic monitoring together with a questionnaire allowed to analyse the “Actual Thermal Comfort” (ASV), obtained through questionnaires, with “calculated thermal comfort” using PET (Physiological Equivalent Temperature) [7]. For questions about Actual sensation of thermal comfort (Actual Votes Sensations - ASV), the respondents were questioned about their trial chill through a 5-point scale ranging from "very cold" (-2) to "very hot" (+2) [8]. The PET index was calculated by the software "Rayman" (version 1.2) developed by the Meteorological Institute of Freiburg [7]. In each measuring point were recorded hemispheric photos in order to calculate the sky view factor (SVF) using the same software.

4. RESULTS The analysis of Thermal Comfort in pedestrian streets in three cities of the interior of Sao Paulo State highlight differences between Calculated and Actual Thermal Comfort and a great users´ thermal sensibility to the weather daily and seasonal changes, which influence the users´ permanence length of time in the evaluated spaces.

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Table 1 brings the average values of the microclimatic conditions of the users´ exposition during fieldwork in the cities of Campinas, Bauru and Presidente Prudente. The data highlight the significant microclimatic differences in the morning and afternoon periods among those cities. Table 1 – Microclimatic conditions during monitoring days in the cities of Campinas, Bauru and Presidente Prudente

Cities

Campinas M

A

Bauru M

A

Presidente. Prudente M A

Temperature ( °C) 27,7 26,8 29,9 16,0 28,0 26,1 22,7 25,4 10,0 22,5 30,1 30,5 35,2 24,6 32,6 Humidity (%) 52,5 51,5 52,5 40,5 64,6 41,3 Mean Mmin 44,7 41,6 41,9 28,2 52,2 37,1 Mmax 58,3 62,8 62,4 59,9 79,1 48,9 Wind (m/s) 0,7 0,8 1,1 1,2 1,1 1,0 Mean Min 0,2 0,2 0,7 0,8 0,7 0,9 Max 1,0 1,3 1,9 2,1 1,7 1,2 Global Solar Radiation (w/m2) Mmin - 95 - 383 304 40 50 - 33 Mmax 270 462 562 282 408 549 Legend: M – morning A - Afternoon Mmin – Mean minimum Mmax - Mean maximum Mean Mmin Mmax

25,1 21,7 28,2

In mild climatic conditions, with cold and dry weather, it was observed a great percentage of the PET within of the range limits from 18-23 °C [9]. In relation to ASV, for those same conditions it was observed a balance between people who felt comfortable and uncomfortable. However, in hot and humid weather conditions, the PET temperatures were out of those limits and the ASV showed a larger percentage of uncomfortable people, reaching 100% in some periods, whose air temperature exceeded 30 °C. In the thermal discomfort conditions, caused by high temperatures and high or low relative air humidity, many users refused to answer the questionnaires claiming the need to leave the place as quickly as possible. Others appointed possible solutions to improve the local microclimatic conditions such as shelter for sun radiation protection and the presence of water fountain. The great users´ thermal sensibility observed in the pedestrian streets analyzed in this paper are in contrast with the study of thermal comfort in convivial urban spaces (squares and parks). The analysis on green public spaces in these three cities of the state of Sao Paulo, Brazil [10], helped to identify that an environmental performance associated with other aspects such as circulation, activities and presence of niches contribute to a good evaluation by users of the spaces and consequently interfere with their perception of thermal comfort, even in adverse conditions. The figs. 8, 9 and 10 show graphs at range PET temperature grouped according to thermal sensation. The range of PET temperature to 50% of the

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

individuals varied from 20 to 29°C in Campinas, 21 to 30 °C in Bauru and 14 to 24°C in Presidente Prudente.

Figure 8: Graphs with the comfort range to pedestrian street in city of Campinas (PET x ASV).

Fig. 12 gathers all the pedestrian streets analyzed and relates the PET temperature range to 235 people (of the total of 519 interviewees) who declared that the thermal sensation in the moment was “neither cool nor warm”. The PET for all interviewees had great variation, the lowest 0,2 °C and the highest 40,1°C. The average PET temperature value was 21,6 °C and the median was 22 °C. The PET temperature range, which includes 50% of the individuals who felt comfortable, varied from 17,5 to 25,3 °C. However, as well as in the individual analysis for each city, that strip temperature overlays other vote range that indicates thermal discomfort. Comparing those results with the thermal comfort limits proposed for the city of São Paulo, Brazil [10] , which varies from 18 to 26°C, were found 59% of the total sample (i.e. 308 from 519). Considerable part of the individuals within that strip of PET temperature declared their thermal sensation as “warm - 18.5%” and as “cool - 17,5 %” as represented in Figs. 12 . Similar analysis on green public spaces in the same cities of Sao Paulo State allowed to identify 70% of all individual who responded neutral temperature within those limits.

Figure 9: Graphs with the comfort range to pedestrian street in city of Bauru (PET x ASV) Figure 11: Histogram for PET temperature in pedestrian streets for ASV=0.

Figure 10: Graphs with the comfort range to pedestrian street in city of Presidente Prudente (PET x ASV)

The PET temperature analysis (Fig 11), for ASV=0), shows a major frequency for the strip between 18 and 30 °C (70% of the sample) and major concentration at 24 °C.

Figure 12: PET temperature range and Actual sensation vote

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5. CONCLUSION

REFERENCES

The studies performed in the pedestrian streets of the three cities of São Paulo state, Brazil presented different thermal comfort limits in each one of the spaces evaluated. Besides, differences between the Calculated Thermal Comfort (by PET index) and Actual Thermal Comfort (obtained by questionnaire) in mild climate conditions (dry and cold weather) and similarities in more adverse conditions (hot and humid or hot and dry weather) were found. In the first case the calculated thermal comfort identified a larger number of people who felt comfortable while the ASV showed a balance between satisfied and dissatisfied people. In the second case, it was observed a great percentage of dissatisfied people in both forms of comfort evaluation. Those results show that hot weather are more critical for the pedestrians and lead to the necessity of a requalification of those spaces aiming to improve their microclimatic conditions and consequently influence the users´ thermal satisfaction and a longer permanence of the user in those spaces. In spite of different thresholds for PET, in each one of the spaces assessed, the range of temperature, which includes 59,5% of all individuals who have responded neutral thermal, range from 18 to 26°C (308 of 519 individuals). This range of variation comes in accordance with the limits of comfort for the PET proposed for the city of Sao Paulo, Brazil [10], adjusted in relation to the range of 18 to 23 °C [9]. It has also been observed a superposition of the sensation votes in every one of the cases evaluated. Thus, it should be emphasized the importance of intensifying similar research in each one of the cities evaluated with the objective of defining more accurately the limits of thermal comfort and to calibrate the values of PET. However, it is recommended the evaluation of Actual Thermal Sensation (ASV) with ranges of continuous values (e.g. a range of values between 0 and 9, referring to the extreme cold and very hot). That may be possible with the use of the continuous scale, replacing the categorical variables of five points, and it will probably allow more precise delimitation of PET values of temperature for different thermal sensations in pedestrian streets.

[1] LYNCH, K. (1960). The Image of the City. Massachusetts Institute of Technology Press, Cambridge, MA. [2] PERSON, E. (2006). Espaços de permanência e passagem: contribuição para a elaboração de diretrizes ambientais e de acessibilidade para o desenho urbano. Dissertação de Mestrado em Arquitetura e Urbanismo. Brasília, Universidade de Brasília. [3] JACOBS, J. (1961). The Death and Life of Great American Cities. Penguin Books, London, p. 221. [4] ROMERO, M. B. (2001). A arquitetura bioclimática do espaço público. Brasília, Editora da Universidade de Brasília. [5] CHRISOMALLIDOU, N.; CHRISOMALIDIS, M.; STILIDIS, L.; THEODOSIOU, T.; KIUGA, L. (2003). Rehabilitation of open space under bioclimatic criteria. In: CONFERENCE ON PASSIVE AND LOW ENERGY ARCHITECTURE, 20th, 2003, Santiago. Proceedings… Santiago: Universidad Católica do Chile, 2003. [6] NIKOLOPOULOU, M; LYKOUDIS, S (2006). Thermal comfort in outdoor urban spaces: Analysis across different European countries. Building and Environmental, 41, November 2006: 1455-1470. [7] MAYER, H.; HÖPPE, P. (1987). Thermal comfort of man in different urban environments. Theoretical and Applied Climatology, v. 38: 4349. [8] NIKOLOPOULOU,M.; STEEMERS K. (2003) Thermal comfort and psychological adaptation as a guide for designing urban spaces. Energy and Buildings, v. 35: 95–101. [9] MATZARAKIS, A.; RUTZ, F.; MAYER, H.(2000). Estimation and calculation of the mean radiant temperature within urban structures. In: Biometeorology And Urban Climatology At The Turn Of The Millenium (ed. By R. J. de Dear, J. D> Kalma, T. R. Oke and A. Auliciems): selected papers the conference ICB-ICUC`99, Sydney, WCASP-50, WMO/TD. [10] MONTEIRO, L. M; ALUCCI, M.P. Calibration of outdoor thermal comfort models. In: PLEA International Conference on Passive and Low Energy Architecture, 23rd, 2006. Proccedings … Genève, 2006: 515-522. [11] FONTES, M. S. G. F; BUENO-BARTHOLOMEI, C. L.; DACANAL, C.; LABAKI, L. C.; NIKOLOPOULOU, M.. Thermal comfort in open public spaces: studies in green areas in cities of the Sao Paulo State, Brazil. In: INTERNATIONAL CONFERENCE ON PASSIVE AND LOW ENERGY COOLING FOR THE BUILT ENVIRONMENT, 3RD, 2010, Rhodes, Proceedings… Rhodes, 2010.

6. ACKNOWLEDGEMENTS The financial support from FAPESP (Fundação de Amparo a Pesquisa do Estado de São Paulo, Brazil) to more comprehensive project co-ordinator for Prof. Dr. Lucila Chebel Labaki (FEC-UNICAMP, Brazil).

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Elaboration of a methodological guide of sound ambiences to evaluate urban soundscapes: the ASTUCE Research Project Catherine SEMIDOR1, Henry TORGUE2, Jacques BEAUMONT3, Aline BARLET1, Julien DELAS2, Cécile REGNAULT2 and Flora GBEDJI1 1

GRECAU, ENSAP Bordeaux University, Talence, France 2 CRESSON, ENSAG, Grenoble, France 3 INRETS, Bron, France

ABSTRACT: The first results of the research project ASTUCE were presented in a previous paper (ICA 2010). The goal of the project is to develop a global approach that helps local authorities, decisions makers, urban planners and town designers in the decision making process. By collecting information about the urban sound environment, identifying those that satisfy the city dwellers’ expectations and those that have to disappear or be modified, short- and long-term strategies will then be validated in complement of the noise action plans in line with the European Environmental Noise Directive. The present paper deals with those elements that should form the basis of the methodological guide. This toolbox is based on the analysis and the synergy of specific sound markers related to the urban centrality and highlighted during the ASTUCE project. It has to assist its future users to find a balance between their objectives and the specific noises that belong to each urban site, its activities, morphology, practices and evolution over time. This paper shows that there are no ready-made solutions, but based on the existing situation a reflection could be made as to whether and under which conditions the quality of the environment in terms of soundscape could be improved. Keywords: urban soundscape, outside acoustic comfort, town design strategy, methodological guide

1. INTRODUCTION The name of this project, ASTUCE, is an acronym that gathers Ambiances Sonores, Transports Urbains, Cœur de ville et Environnement: Sound Ambiences, Urban Transport, City centre and Environment. This research project is aiming to provide a relevant methodology to improve the environmental quality of city centres by integrating the sensitive character of urban sound ambiences and the city dwellers sound experience. Two goals have to be reached: •First, to gather and compare different methods to study city centre sound ambiences. •The second goal of this project is to develop a guidebook to help local authorities, urban planners and town designers in the decision making process about sound ambiences (study, design and management). This discourse not only fits into the framework of a suppression of the harmful effects due to noise but, in a more particular way, in the prospect of a contribution to the environmental sound quality of the urban centres. Three approaches by three French laboratories: •GRECAU (research group on environment, architectural & urban design – School of Architecture and Landscape- Bordeaux) •CRESSON (centre for research on sonic space & urban environment - School of Architecture Grenoble) •INRETS (national transport research institute Bron).

The methods of GRECAU are based on recordings of soundscapes, surveys and observations about uses and perceptions of city dwellers. The methods of CRESSON are based on the memory of the city dwellers and on their imagination from and with urban soundscape. INRETS is a research institute specialised about transports. Their methods are mainly quantitative, using measures, modelisation and simulation. The three teams worked at the same time on the same site. The methods, the quantitative and qualitative analysis, and the results are exchanged and critically compared in order to determine their complementarities and/or their exclusiveness of application, from subjective to rational. The two case studies sites are the historical centres of Bordeaux and of Grenoble. •In each city, there are several modes of transportation among which the tramway •Similarities in functions, urban activities and transports •Differences according to urban morphologies: - a large square in Bordeaux (Place Pey-Berland: cathedral in the middle of a large place surrounded by the tramway) - a U-shaped street in Grenoble (Rue FélixPoulat: one narrow street which is an important axis of the downtown area). The in situ survey organisation and some first results were presented in a previous paper (ASTUCE Research Project: one way to evaluate urban soundscapes, ICA 2010) by the authors.

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2. COLLECTION OF SOUNDSCAPE'S ACTUAL EXPERIENCE

In Grenoble, the sequencing can also define six zones identified in colour in Figure 2.

2.1. Data from the Soundwalks To conduct its research on urban soundscape [1], GRECAU developed the soundwalk method, taking inspiration from the work proposed by K. Lynch [2]. As the method has been described in numerous publications [3] [4], only the principle will be given here. As stereoscopic vision gives a threedimensional effect, stereo listening creates a realistic sound environment. Binaural recordings provided following routes which are specific for the studied urban space, are used to characterize the spatial distribution of sound energy, especially to differentiate the spaces according to their morphology: open (square, plaza etc.) or closed (Ushaped street, courtyard and so on). All along the routes photos are taken in order to keep evidences of the urban morphology and the occurring significant sound events. The analysis of the acoustic images and the listening to binaural recordings made during the soundwalks in each city at different times allowed to identify areas with their characteristic sounds which vary little during all the day. This site segmentation can be done according to different criteria, also complementary: urban morphology, types of activities or sound ambiences. The decision to do the two soundwalks always in parallel gives a more refined approach to this fractionation. The analysis of the recorded soundscapes revealed animated “sequences” characterized by a lot of human activities, such as cafe terraces or pedestrian walkways (Equivalent Sound Level higher in the medium frequencies range on the acoustic images), and some other ones characterized by car traffic and public transportation (Equivalent Sound Level higher in the low frequencies range on the acoustic images), and quieter ones where sound sources of natural origin are clearly perceived (lower background noise level). This sequencing revealed in Bordeaux 7 zones, identified in colour in Figure 1.

Figure 2: Splitting zones of the Rue Félix Poulat related to sound “sequences".

Related tables (Table 1 for Bordeaux and table 2 for Grenoble) give a very condensed description of the sound characters of each zone based on comments from the listening and the analysis of soundwalks. The detailed comments have to be illustrated by the acoustic images (quantitative representation of the contents of the recordings) of each zone in order to complete the evaluation of the sound quality of the site. Table 1: Summary comments from the listening and analysis of the sound walks in Bordeaux

Zone 1

2 3

4 5

6 7

Figure 1: Splitting in zones of the Place Pey-Berland related to sound “sequences".

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Main sound identity Calm in an open space

Sound sources to remember Sound of the fountain and the chirping of birds emerge with the passage of trams, cars, motorcycles.

Fairly noisy in an almost closed space Noisy in an almost closed space

Cars, motorcycles and trams

Very noisy in an open space Fairly quite in an open space Very noisy in an almost closed space Calm in an open space protected by the cathedral

Sounds of footsteps, discussions, nature (birds,…), cars, motorcycles and trams Tram, crossing roads, car park exit Sounds of discussions, playing (football, skateboard…) and of singing birds Cars, scooters and trams Sounds of discussion, footsteps and outdoor cafés

The Place Pey-Berland brings many urban activities together, each with a particular sound, composing a multifaceted soundscape.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 2: Summary comments from the listening and analysis of the sound walks in Grenoble

Zone 1 2 3

4 5

6

Main sound identity Very narrow and noisy U-shaped area Fairly noisy in an almost open space Fairly noisy in a well differentiated space on each side of the tramway in a Ushaped street Fairly quite in an almost open space Very mechanical ambiance sound in a narrow Ushaped street Very noisy in a very narrow Ushaped street

Sound sources to remember Trams, cars, motorcycles and cycles. Pedestrians and trams Carousel, shops, trams, some motor vehicles, conversations and sound of footsteps Cafes, restaurants, ice cream sellers, fountain, traffic Trams, motor vehicle, rollers and skaters, and sound of footsteps Open shops, conversations, cars, scooters and trams

The rue Félix Poulat unites a fairly standard combination of problems related to the management of a miscellaneous soundscape of a city centre. 2.2. Data of urban morphology An analysis grid of elements of the urban space completes the commentaries on the recordings and the photographs. The data are collected and arranged by means of tracings illustrated with photos and drawings, and then transferred on index cards and / or maps that can be inserted into GIS-type databases. They relate to traditional data such as shapes, materials, dimensions of buildings and may be supplemented by urban planning data. The other urban elements listed and transcribed by means of tracings are the modes of transport, the various activities potential noise sources whether from human, mechanical or natural (wind, water, wildlife and so on) origin. The items identified are grouped into 3 categories: • Morphology of the site: soil, buildings, vegetation, urban furniture. • On-site activities: modes of transportation, human activity, mechanical activity. • Other elements (sound sources): water, air, fauna etc. The data from the survey of urban space are those used by the urban planners of the city. Thus they are necessary to evaluate the quality of the sound environment. For the ASTUCE project they were one of the criteria for selecting sites, one with rather large open spaces and the other U-shaped one very closed. They will also be common to all project partners. At the 2 sites the cornice outlines of the façades are very close to the balconies, mostly paired with ornate stone coverings. The data obtained are the building heights, topography of the parcel, nature of soil

materials, the presence of vegetation, water in all its forms and types of urban furniture at different scales. The Place Pey-Berland in Bordeaux is the heart of the city as it is the location of the cathedral St André and the City Hall. Since the implementation of the tramway in late 2003, two lines cross and have a stop on one part of the square where also motor vehicles are authorized. The other part is only pedestrian and serves as a purely pedestrian forecourt to the church and the town hall with the terraces of cafes at the edge of the square. Although sliding sports are forbidden, the forecourt is used by many skaters and rollerbladers. The site is surrounded by three to five-level buildings mostly housing administrative offices. It is a very mineral area (much of the ground is covered with slabs of granite and gravel) despite the presence of a few trees around it. Although there is plenty of street furniture (benches, lighting masts, traffic lights, bollards, tramway shelters etc.), the area of the square is large enough not to seem crowded. One of the traffic lanes used by the tram is oriented north-south, the other east-west. On the east side, the forecourt of the Palais de Justice with its fountain with cascading water has been integrated into the study site. On the north side, a small square with trees (Place Jean Moulin) is an appendage that can not be dissociated from this area. The rue Félix Poulat in Grenoble is the major axis of the downtown area. It covers the 200 meters separating the Place Victor Hugo and the Place Grenette (which can be considered as its extension to the north) and changes then in the rue Raoul Blanchard oriented westward. Two tramway lines pass through this street with two stations at each end. Although officially pedestrian, bicycles, rollerbladers and, despite everything, many motor vehicles pass through the street related to its residential and commercial functions. The whole Place Grenette, occupied by sidewalk cafes and at the north edge by a fountain, is rather mineral. This overall vertically U-shaped and tree-planted street has horizontally a trapezoidal shape and is lined with buildings whose height is very homogeneous (6 floors). It is a very crowded space with very diverse street furniture from plant and flower boxes to a bandstand and carousel with wooden horses. It is crossed by several streets that are not all pedestrian. 2.3. Psycho-environmental data In the framework of this project, the collection of sensitive data is based on the method of a questionnaire survey of a sample of passers-by on the sites. The environmental study captures the overall context of occupation of different spaces in order to interpret the fine sound environmental assessments collected. The urban noise is considered here both recontextualized and articulated to the various aspects of the physical and social environment since the subjects perceive their environment in a poly-sensorial way and the perception of one aspect influences the perception of the others.

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The questionnaire consists of 16 questions, composed mainly of closed questions and scales of judgement, so that the filling out of the questionnaires are relatively fast and easy to achieve (10 minutes). During the two research campaigns simultaneously carried out with the collection of other data, 60 subjects in Bordeaux and 53 in Grenoble agreed to participate in this survey. We have taken great care in constructing our samples in terms of personal characteristics such as the distribution between men and women and the representation of different age groups across all sites. Despite this, the different age groups and different occupational groups, although almost all present in our samples, are not represented in equal proportions. Concerning the composition of the soundscape, the Place Pey Berland appears rather heterogeneous, although some sources are common to all sequences. This diversity seems consistent with the various functions of this public space. First, the tram is both the source cited by most subjects and most often identified as the most representative source of the site (except in a sequence where the fountain is the most characteristic source). Cars are also very present even if they do not pass directly in the zones 7 and 5 in particular. Conversations are perceived all over the place, although to a lesser extent in the zones 6 and 4 (less frequented by pedestrians). Finally, the tram horn is also a remarkable source of the square, since it is common to 5 of the 7 zones. Only the birdsong is perceived as enjoyable on a large part of the Place Pey Berland and by a large majority of the subjects. The tram is a rather popular sound source in many zones. Besides this, it is the only traffic source which is described as pleasant. As for annoying sources, we find mostly traffic-related sounds such as cars and motorcycles / mopeds. The soundscape of the rue Félix Poulat is essentially composed of 4 sources present in almost all sequences: the conversations, footsteps, cars and trams, the most representative source of the street (except for zone 4 where the fountain is the most characteristic source). The most pleasant sources are related to the human presence (conversations, footsteps and restaurants / cafes), while the most disturbing sources are more related to traffic noises (cars, trucks etc.). The disturbing aspect of these sources is also frequently associated with the incongruity of its presence in a space reserved for pedestrians and tram. The solutions proposed to improve the acoustic comfort are the same on both sites, i.e. either an elimination of these sources or their masking by music, vegetation, installation of a fountain etc. About the temporal evolution of the sound environment of the two sites, about one of two subjects believes that the acoustic ambience of the place or the street changes during the same day and identifies two main opposed periods in Bordeaux (rush hour/off peak time, day/night or with/without tram) and unrelated to neither opposition, neither complementarity in Grenoble.

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The atmosphere on the Place Pey Berland, taken as a whole, is rather pleasant in the evening and during the off-peak time; it was during this latter period that the place is considered to be the quietest. In contrast, day and rush hours are two periods where the soundscape of the Place is considered rather unpleasant and rather noisy. As for the rue Félix Poulat, the soundscape is particularly pleasant at night, it was during this period that the place is quieter. In contrast, the day and the afternoon are two periods where the soundscape is considered rather unpleasant and noisy.

3. COLLECTION OF THE IMAGINATION ON THE SOUNDSCAPE 3.1. The qualified sequences The sequencing of the site is the first analytical work organizing the results achieved by the commented walks of CRESSON [5]. A downtown tour, in an in appearance homogeneous territory, reveals thresholds, zones, markings that identify sensitive sequences (which means that the senses reveals them) commonly shared. The sequencing is a crucial way of understanding the urban space for the description and the uses. On the one hand, the space is split according to a segmentation shared by its users and, on the other hand, each sequence is qualified by a perceptible colour and an associated image, a dominant feature or judgement. If the division leads to some consensus, the qualification process gives a range of comments which reflect the views sometimes opposing, divergent and often linked to various practices of those same spaces. What is striking, however, in our survey, is the convergence of images of a dominant qualifying feature of the site from which diverge experiences and opinions. The spatial division of the sequences crosses the morphology, uses and sensitive criteria. When a discontinuity is expressed, a new sequence is mentioned. Anthropological function of spatial appropriation, the division may tend to increase the levels and areas, sometimes exaggerating the importance of certain nuances. But these individual tendencies are corrected by the collective review of results. 3.2. Status of collected comments In the methodology of Cresson, interviews are fully registered in order to transcribe them word for word, with their doubts, their silences, their repetitions, their findings and platitudes, including what is drawn on oral communication and verbalization elements. We get a full collection of basic and key expressions, without omissions or additions. This sum, which represents nearly 500 pages for this research, is the plain text that tells the way the respondents relate their urban space. Their words express a multitude of diverse information: practical attitudes but also points of view, images, anecdotes, stories, rumours, feelings, judgments and so on. The technique of guided qualitative interviews provides access to elements comprising a complex situation that combines spatio-

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

temporal aspects, experienced and projected aspects. Among the expressions collected three registers must be distinguished: - The actual practices ("I do this", "I'm going there"), relating to the factual description of actions and sites, - Opinions, judgments ("I think we should act on...", "installation of such equipment is an improvement because of...") that express feelings and pronounce a positive or negative opinion, - Images that refer to a metaphor and the field of poetry (the area is a "spider web", "a fortress", a "hive", a "nest" etc). These three modalities mix and are rarely isolated. Although the issues can induce one or the other, the collected comments are most of the time, free enough to keep a real polyvocity and its broadness of expression. By crossing the actual practices, explicit discourses and images, the plain text looks like a panorama that reflects the complexity of the site and referred time. The entire text of transcribed interviews actually gives access to thousands of information units that constitute the raw material of the analysis, consisting of micro-descriptions, fugitive or developed notes, attitudes, practices, anecdotes, judgments, images and sensations, exposed as a puzzle that reveals in a photographic way, the collective vivid words for an approached situation. The objective of this collection of raw information is to make perceptible the emergence of different words which directly reflects the plurality of the lines of force, of cohesion or conflict, and which acts in a given territory. Living in, in the sense of invested space, reveals plural and contradictory discourses that need to be understood as it belongs for a big part to an imaginary world. The words of residents express stories, opinions and also mythical narratives related to a specific lexical field [6].

After the phase of comparing and pooling the results of our methods, we extrapolate our common process developed from two particular cases, a description and intervention tool on urban noise situations: The Guide of urban sound environment first presented in general terms, then in the form of a toolkit specific to each context. The principle is to model a situation by describing simultaneously twelve balances between polarities, both purely quantitative and purely qualitative or mixed. It consists of creating an organizer of the descriptive elements distributed according to a series of bi (or multi)-polarities.

between polarities. The position of the twelve cursors shows the current status of the situation and can, in simulating a change on the one or the other, project an adjustment/improvement or a correction. The balances are grouped into three categories: • Contextual balances 1. The balance of urban morphologies What is the equilibrium of general forms (silhouettes, skyline, height, volume, open, L, U etc)? Between built and unbuilt, between low and high, compact and spaced 2. The balance of surfaces and facade materials Between continuous and discontinuous, between absorption, diffusion and reflection, between architectural styles and so on 3. The balance of soil materials The soil considered as reflecting element and as sound source. What proportion between the various coatings (hard minerals, grains or gravel, soil plants)? 4. The balance of vegetation Taking into account proportion, nature and noise impacts of plant material. 5. The balance of noise impacts of urban furniture To treat by category: Art, running water and fountains, bus or tram, benches, trash cans, signage elements etc • Acoustic balances 6. The balance of sound sources The balance between natural sounds (climatic elements and fauna), human sounds and mechanical noises. 7. The balance of sound levels Low/High. Quantitative indicators of the site: multiple Leqs, emergences, background noise etc 8. The balance of frequencies (or frequency signatures) The balance between the bass, midrange and treble • Functional balances 9. The balance of flows The balance of the various modes of transportation, the relationship crossed spaces / parked spaces, the density ratio (residential or of use) and so on 10. The balance of activity types Work, leisure, shopping, home and so on with their sub-categories 11. The balance of temporalities The distribution of different periods and sound rhythms: day / night, time of day, week / weekend, sun / rain, school time / vacation time, winter / summer etc 12. The balance of site-specific sound signals Identify and describe the sound symbols and identifiers of the place, characteristic but not unique (bells, bells of horses and so on), those that are unique (Big Ben, bell tram etc).

4.1. The sound markers of centrality: twelve balances

4.2. A methodological toolkit for each specific site

The modelling of each site, or any urban situation, is achieved through the use of twelve sound balances (markers) characterizing the site. Each balance describes the state of equilibrium

Three steps describe the process of approaching a particular urban situation: - The cutting in qualifying sequences (spatial and temporal) involving different scales and their nesting.

4. PROPOSALS FOR A METHODOLOGICAL GUIDE: SOUND AMBIENCES AND CITY CENTRE

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How the site adjusts the differentiated zones, according to various criteria of analysis (physical, spatial and social)? - What are the emerging characters (spatial, architectural, sound, functional, users etc)? How this site does manage the equilibrium of the different balances? - In the current situation in the project: on which cursors do we take action to promote the new desired equilibrium? What to do and what to avoid. What tasks and what competencies are required? By developing a multidisciplinary tool for the description of urban soundscapes, this research is aims not only to eliminate a nuisance due to an overload of noise but in a more particular way to contribute to the environmental quality of urban life, as different local stakeholders have the compelling need for indicators that link the physical, spatial and social aspects.

5. CONCLUSION The indicators, which combine subjective and rational elements, are involving not only the knowledge of experts observing the site but also the expertise of residents and practitioners who reveal by their stories the objective facts, the feelings and projections. This guide does not replace the methods of each spatial discipline but intents to be a framework for an open mutual dialogue. It is in the intersection of measurements and calculations of physical data (the measured data (NF S 31-130) and the noise maps of each city analysed by INRETS are not presented here, but the quantitative results from the soundwalks illustrated by acoustic images fit with their values), technical and aesthetic descriptors of spatial data, effective practices, experiences and representations of feelings in situ, that the changing and complex reality can be approached. By proposing indicators adapted to the qualification of urban environmental noise in addition to the prescribed indicators as the Lden or the Lnight which are used for the noise maps, this project would like contribute to show all the interest and the potential of sound for city management and design. Let us listen to our cities. The urban life is a composition of mechanical, natural and human sounds, as a sound signature. Beyond all other classifications, every city has its own sound identity. The approach of the ASTUCE research project articulates the three main elements in the field of sounds: acoustics, spatial organisation and social representations. This project aims to show the interdisciplinary importance of sound, its potentiality in the development and management of our cities and wishes to contribute by offering new tools to assist all concerned parties. If we do not attempt the methodological experimentation by offering new tools, we do not give any chance to seize and act on inherently interdisciplinary phenomena.

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6. ACKNOWLEDGEMENTS The authors acknowledge the support of a research grant from ADEME. They also are grateful to all the students who participated very efficiently in this research during their training course at GRECAU or at CRESSON.

7. REFERENCES [1] R.M. Schafer, The tuning of the world, (A. Knopf ed, NY, 1976). [2] K. Lynch, The image of the city, (The MIT Press, Cambridge, 1960) [3] C. Sémidor, "Listening to a city with the soundwalk method". Special Issue "Soundscape" Acta Acustica united with Acustica, vol. 92, 959-964 (2006) [4] GRECAU-Bordeaux, "Recommendations for Soundscape Design". Silence European Research Project WP I 2005, Convention Polis 6th PCRD, Final Report, (February 2007) [5] J.-P.Thibaud, "La méthode des parcours commentés". in L'espace urbain en méthodes. (Dir. M Grosjean and J.-P Thibaud, Ed. Parenthèses, Marseille 2001), pp. 79-99. [6] H. Torgue, L'imaginaire des sons. (La GéoGraphie. "Géographie et musique", Editions Glénat, Grenoble, 2009)

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) PLEA 2011 ISBN - 27thxxx-x-xxxx-xxxx-x Conference on Passive andstick) Low xxx-x-xxxx-xxxx-x Energy Architecture, Louvain-la-Neuve, Belgium, - ISBN (USB @ Presses universitaires de Louvain13-15 2011 July

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Adaptive Outdoor Comfort Model Calibrations for a Semitropical Region Mate THITISAWAT, Kasama POLAKIT, Jean-Martin CALDIERON, Giancarlo MANGONE College for Design and Social Inquiry, Florida Atlantic University, Fort Lauderdale, USA. ABSTRACT: This paper is a part of a research project funded by Architectural Research Centers Consortium (ARCC) and Florida Atlantic University (FAU). The project focuses on finding a way to assess outdoor comfort and developing design criteria for a semitropical region of South Florida. A series of surveys were conducted in the summer and fall seasons to obtain participants’ sensation votes corresponding to recorded climatic parameters. More data need to be gathered for the calibration and validation. This paper attempts to evaluate different models using the survey data, and identify strong candidates for further study. The models were all based on Predicted Mean Vote (PMV), an index traditionally used to assess indoor comfort. Results from the PMV equation exhibited a promising trend, but needed some adjustments. It was found that a calibration alone could not improve its prediction. After some computational experiments with different adjustment strategies, five model candidates yielded high rates of agreement with Actual Sensation Votes (ASV). Adaptive and separated calibration approaches applied to the PMV compensated participants’ psychological adaptation to the outdoor condition. They improved the PMV-based models’ predictions considerably. Keywords: outdoor comfort, PMV, model calibration, semitropical region, adaptation

1. INTRODUCTION South Florida is located in a semitropical region that has a unique climate compared with the rest of the country. Before the popularity of the air conditioning technology, people in South Florida learned to create and live in favourable microclimates. Their attempt towards thermal adaptation is reflected in historic building designs and lifestyles. Unfortunately, the old lifestyles and passive design strategies have been replaced with the new energy guzzling technology that guarantees a comfortable environment defined by indoor comfort standards. A current design practice of both indoor and outdoor spaces in the region emphasizes more on appearances, and standardized construction methods than the design strategies. This summer-fall pilot study includes investigations on assessment methods of the outdoor comfort, and compensation for adaptation. After the pilot study, methods will be selected for further developments. More study will be conducted for other seasons to complete the developments of selected assessment methods. Subsequently, this research project will also propose design criteria and implications for the design of outdoor spaces for cities in the semitropical area. The proposed assessment methods and criteria will promote energy saving and heightened human comfort. The study on outdoor comfort can be used to support design decision of outdoor public spaces. Extending the use of the spaces through a good design practice has the potential of increasing outdoor activity, leading to increases in commercial revenue, property values, and opportunities for social interactions. In addition, a good outdoor microclimatic condition can improve the indoor comfort level [1].

Four sites are chosen for the study. They are urban public spaces. They include two pedestrian corridors (Las Olas Blvd., and Riverwalk), and plaza/park like spaces (FAU Plaza, and Main Library Park). The surveys are conducted during daytime when people use the public spaces more. Two of the sites have more manmade features, and the other two have more natural elements (vegetations and a river).

2. LITERATURE REVIEWS 2.1. Challenges in Outdoor Comfort Studies The thermal quality of the outdoor environment varies significantly from the typical controlled interior thermal environment. Outdoor environment have greater fluctuations in temperature, humidity, air movement, radiant heat, solar radiation. Moreover, the complexity of the outdoor environment influences the variety of these parameters. Humans feel comfortable in a wider range of thermal conditions when inhabiting exterior environments because they feel they do not have control over the factors that determine the thermal qualities of the space [2]. It is recognized that the thermal comfort is not defined only by the environmental parameters. Human psychology also has a strong influence in the perception of comfort. Therefore, it is important to include psychological adaptation parameters, namely naturalness, expectations, experience (short/longterm), time of exposure, perceived control, and environmental stimulation [3]. Although a widely use thermal comfort indicator such as Predicted Mean Vote (PMV), and adjusted PMV have shown to be able to predict thermal comfort in general, they are not able to fully account for the wide variation between objective and subjective comfort evaluation. The psychological adaptation parameters have a variant percentage of impact, and should be considered in relation to

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whether these parameters can impact design decisions, and vice versa. Research has shown that quantifiable, microclimatic physical parameters can only account for approximately 50% of the variation between subjective and objective comfort evaluation. In depth quantification and correlation between psychological adaptation parameters presented here and their impact on thermal comfort has not yet been rigorously developed. However, research has shown that a thermal comfort model that excludes psychological adaptation is not adequate for predicting outdoor thermal comfort [4]. 2.2. Methodologies Used in Previous Studies Several methods have been employed by previous studies. They can be classified as follow: 1. A statistical approach (linear and nonlinear regression analysis) is confined to certain predefined relationships, and climatic ranges. The advantage of its simplicity. It does not require an iterative calculation. 2. A steady state thermo-regulatory equation is typically used in indoor comfort assessment. Its combination of physics and statistics present high potential for the assessment. 3. Dynamic methods are more advantageous over the statistical approach because it is more universally applicable. 2.3. Outdoor Comfort Indicators Different research projects have different preferences for comfort indicators. Examples of the indicators include: 1. PMV is described by a curve fit equation based on human thermal regulation and empirical data of sensation votes. The PMV calculation requires a convergence, thus iterative calculation. 2. Percentage of People Dissatisfied (PPD) is based on the PMV. 3. Physiologically Equivalent Temperature (PET) is based on thermo-regulatory capacities of a human body [1, 5]. It is based on the Munich Energy Balance Model for Individuals (MEMI). 4. Frequentation map based on the method of Multi-Agent Systems (MAS) to simulate how virtual pedestrians move through an open space. Human thermoregulatory system and a model simulating microclimate conditions are used to simulate pedestrian motion and individual decisions. It establishes space-time dynamics reflecting a time lag in the human response. A model based on smooth fuzzy logic is used to simulate the decision for the movement [6]. The PMV is selected for evaluation and calculation development. It is called “revised PMV” whose calculation is based on [7]. A research question is whether the widely used indoor comfort index like PMV can be adjusted and improved for the outdoor comfort assessment.

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3. SURVEYS AND DATA 3.1. Survey Questionnaire A 9-point thermal sensation scale is shown with its numerical equivalent in Table 1. It is an extension of the ASHRAE scale, and different from the Bedford scale. Table 1:9-point thermal sensation scale

Bedford

ASHRAE

9-point

Much too hot

Hot

Hot

3

Too hot

Warm

Warm

2

Very hot

Comfortably warm Slightly warm

Slightly warm

1

Comfortable

Neutral

0

Slightly cool

-1

Neutral

Comfortably cool Slightly cool Too cool

Cool

Cool

-2

Much too cool

Cold

Cold

-3

Very cold

-4

Beside the sensation vote, the following information is acquired. - Age - Clothing items - Gender - Exposure to the sun - Skin color - Height - Weight - Place of origin - Starting time - Date - Sensation perception of comfort, humidity, wind speed, and sunlight, - Activity performed in the last 15 minutes - Clothing addition/removal needed - Outdoor exposure duration - Average hours of outdoor exposure - Average hours of air condition exposure Chun recommends that the information of activity performed 15 minutes prior to the survey may improve the prediction [8]. It also suggests that the exposure to the air conditioned environment affects the thermal sensation. In addition, point measurements of skin and clothing temperatures are also taken. Using the spot measurements in the PMV equation does not yield as agreeable results as using iteratively calculated clothing and skin temperatures. 3.2. Climatic Data Acquisition Various data loggers and sensors are employed to collect climatic data. A portable thermal comfort monitoring unit is used to record dry and wet bulb temperature, relative humidity, and mean radiant temperature. A hot wire air velocity sensor is attached to it. This monitoring unit is attached to a tripod. Two pyranometers are connected to a datalogger to collect global and diffuse radiation. Each pyranometer is mounted on a wooden box attached to a tripod used to raise the sensors up 3 feet high, an approximate height of the body core [9]. The one measuring the diffuse radiation is shaded by a semicircular shield to block out direct radiation. In this phase of the model development, shortwave radiation data are not used since the recorded mean

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July

2011 PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

radiant temperature include the effect from the radiation. Nevertheless, the radiation data will be used in a subsequent study. The data recording is synchronized, and a sampling frequency of 1 minute is applied. Averaged data recorded 10 minutes prior to each sensation voting are used with each set of survey data. More information about the data can be found in a complementary paper [10].

the PMV and ASV is 1.2382. When the PMVs are negative, most participants feel comfortable. This shows that they adapted to the cooler condition. Nevertheless, the calculated PMV exhibits the same trend as the ASV. Therefore, it is reasonable to try to improve the prediction by recalibrating the equation.

4. MODEL CALIBRATION An assessment development starts with revisiting an empirical equation developed to predict indoor comfort through the PMV. The equation is a combination of physical and empirical models. The physical model is a thermoregulatory model of the human body, and the empirical model defines thermal sensation as a function of a thermal load or thermal storage. The thermal load represents the imbalance or an unknown quantity of the heat loss and heat gain through the body. The thermoregulatory equation is based on a heat balance equation that accounts for: S: Heat storage M: Metabolism W: External work R: Heat exchange by radiation (from the outer surface of clothing) C: Heat exchange by convection (from the outer surface of the clothing) K: Heat exchange by conduction (through clothing) E: Heat loss by evaporation (sweating) RES:Heat exchange by respiration (latent and sensible/dry heat) The heat balance equation of the body is expressed as: S = M ± W ± R ± C ± K - E - RES

-0.036M

+0.028)*S

Calibrations and recalibrations in this paper are performed in Matlab using lsqcurvefit function. The first recalibration attempts to curve fit equation (2). The new equation (PMV2) can be expressed as: (-0.0355*M)

PMV2 = 0.3278*e

+0.0362)*S

(3)

A simulation is performed using equation (3) and collected data as inputs. Figure 2 compares simulation or calculation results of the PMV2 equation and the ASV. The RMSE between them is 1.5039 indicating that the prediction using equation (3) is worse than that of the PMV equation. This indicates that calibration alone cannot guarantee a better prediction. Some strategies must be developed to improve the agreement of the results.

(1)

The calculation requires information of dry bulb temperature, wet bulb temperature, relative humidity, air velocity, mean radiant temperature, metabolism rate, and clo value (insulating value of the clothing). When the heat storage (S) becomes zero, the heat balance is reached. The PMV is used to predict the thermal sensation, a seven-point scale (hot, warm, slightly warm, neutral, slightly cool, cool, cold). The sensation scale is known as ASHRAE scale. The prediction relies on an empirical model as a function of the thermoregulatory equation. It is based on an exponential fit curve in the following equation: PMV = (0.303*e

Figure 1: Scattergraph showing the predictive power of the PMV equation

(2)

Programming codes for this study is based on [7]. Actual Sensation Votes (ASV) from surveys are compared with calculated PMV to investigate the prediction of the PMV equation (Figure 1). The Root Mean Square Error (RMSE) is employed as an indicator for the predictive power or prediction agreement. A low RMSE indicates that the prediction agrees with the collected data. The RMSE between

Figure 2: Scattergraph showing the predictive power of the recalibrated PMV equation

There is a difference of the agreement in hot and cold conditions. The human body uses different mechanisms for regulating its temperature [5]. Therefore, the next trial is to perform separate recalibrations. The adaptive comfort temperature is used to separate the data into two sets. An equation for the most likely comfort temperature (Tc) shown below is developed by [11]. Tc = 13.5 + 0.54 To

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2011 PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

where To is the outside air temperature. The two distinct data sets are (i) Tc ≥ To, and (ii) Tc < To. The separately recalibration results in the following equations: PMV3 = Fi*S where Fi is a curve fit equation. If Tc ≥ To (-0.0342*M) +0.0284 F1 = -0.4005*e If Tc < To F2 = 0.4371*e(-0.0325*M)+0.0196

(5) (6) (7)

Figure 3 compares the prediction of the separately recalibrated PMV (PMV3) equation and the ASV. The RMSE between the ASV and the separately recalibrated PMV is 0.7043, which is a considerable improvement over the last two equations.

Figure 3: Scattergraph showing the predictive power of the separately recalibrated PMV equation

To identify the next strategy, results from the original PMV equation are investigated. A comparison between the temperature difference ( |To - Tc| ), and prediction error ( |ASV – PMV| ) is performed (Figure 4). Despite few disagreements, there is a trend demonstrating that the magnitude of the prediction error increases as the temperature difference grows. Therefore, an adaptive adjustment using the temperature difference may be a good candidate that can be used to compensate the prediction error, and to improve the PMV equation.

Figure 4: Sorted temperature difference and PMV prediction errors

Currently, there are not enough data points and range in order to conclude whether the relationship

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between the difference and the error should be linear or polynomial. In addition, more studies should be performed in order to find relationships between the prediction error and other parameters. A calibration of the PMV equation is performed without the knowledge of the relationships. The following equations are obtained from the calibration using the linear compensation. The new PMV equation is called PMVFAU1. PMVFAU1 = F3*S+0.8150*|To - Tc| where F3 = -0.4465*e(-0.0635*MW)+0.0282

(9)

Figure 5 indicates a similar agreement compared with Figure 3. The idea of using the adaptive comfort temperature to adjust the PMV equation shows some promise. The RMSE between the ASV and the PMVFAU1 equation is 0.6826.

Figure 5: Scattergraph showing the predictive power of the PMV-FAU1 equation

Following the success of PMV3 equation, the separate calibration is applied to the next attempt. The calibration yields the following equations: If Tc ≥ To PMVFAU2 = F4*S+0.6407*|To - Tc| where F4 = -3.5915*e(-0.0815*M)+0.0248 If Tc < To PMVFAU2 = F5*S-0.8199*|To - Tc| where F5 = 8.0380*e(-0.0884*M)+0.0405

(11) (10) (13) (12)

Figure 6: Scattergraph showing the predictive power of the PMV-FAU2 equation

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 2011

Figure 6 shows similarity to the last two attempts. The RMSE between the ASV and the PMV with a separate adaptive adjustment (PMVFAU2) is 0.6082. The improvement over PMVFAU1 is less than 0.1 in the RMSE. Furthermore, PMVFAU1 is less complicated with regard to the computation. To compensate for psychological adaptation and expectation that increase human tolerance to warmer or cooler conditions an adjustment to the PMV equation is proposed by [4, 12]. A new equation is called PMVnew. PMVnew = 0.8*(PMV – DPMV) where = -4.03+0.0949*To+0.00584*RH+ DPMV 2 1.201*(M* Icl)+0.000838*To

(14) (15)

The RMSE between the ASV and calculated PMVnew is 1.9005. The RMSE and Figure 7 indicate that in order to adopt the equation, the PMVnew equation needs a recalibration with the data from this climate.

powers of PMVnew2 and PMVFAU1 equation are comparable. The separate calibration strategy has produced improvements. Together with PMV recalibration, it is again applied to the next attempt leading to equation (18-24). If Tc ≥ To (18) PMV new3 = 0.1727*(PMVrecalibrated-DPMV3) where (19) PMVrecalibrated = F6*S F6 = -2.0212*e(0.0007*M)+2.3841 (20) DPMV3 = 3.2351-1.9070*To +5.4480*RH + 2 0.8830*M*Icl+0.0545*To (21) If Tc < To PMVnew3 = 0.3078*(PMVrecalibrated-DPMV3) (22) where (0.0004*M) = 0.2407*e -0.1893 (23) F6 DPMV3 = -8.9164+0.0167* To -8.1784*RH+ 2 0.2197*M*Icl+0.0149* To (24) This last attempt yields the RMSE of 0.6064. Figure 9 shows noticeable improvement over the last attempt. Thus far, this attempt generates the most agreeable results.

Figure 7: Scattergraph showing the predictive power of the PMVnew equation

The recalibration of the PMVnew equation (14 and 15) leads to PMVnew2 equation (16 and 17). (16) PMVnew2 = 0.6574*(PMV-DPMV2) where DPMV2 = -21.2043+1.3601*To-0.7592*RH(17) 0.0422 *M*Icl-0.0225*To2

Figure 9: Scattergraph showing the predictive power of the PMVnew3 (separately recalibrated PMVnew equation)

Table 2 presents a comparison among different equations. There are five candidates that perform considerably better than their predecessors. Two of them do not require separate calculations. The best four namely, PMVFAU1, PMVFAU2, recalibrated PMVnew, and separately recalibrated PMVnew, are based on the adaptive adjustment. Table 2: A comparison of different equations

Figure 8: Scattergraph showing the predictive power of the PMVnew2 (recalibrated PMVnew equation)

Figure 8 shows a considerable improvement over the calculated PMVnew. The RMSE between the ASV and calculated PMVnew2 is 0.6982. The predictive

Assessment

RMSE

Separation

PMV

1.2382

Recalibrated PMV

1.5039

No

Separately recalibrated PMV

0.7043

Yes

No

PMVFAU1

0.6826

No

PMVFAU2

0.6082

Yes

PMVnew

1.9005

No

Recalibrated PMVnew

0.6982

No

Separately recalibrated PMVnew 0.6064

Yes

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

5. CONCLUSION

8. REFERENCES

The paper presents a series of equation calibrations. Strategies for the calibrations are based on the PMV and a previously proposed adjustment. Recalibration of the previously calibrated equation does not always guarantee better prediction agreement. The recalibrated PMV equation does not produce improvement unlike the recalibrated PMVnew. The paper presents a series of equation development strategies. Based on a preceding calibration and evaluation, a subsequent strategy is selected. There are three successful strategies included in the paper. The first one is developed from the agreement between the magnitude of adaptation and the difference between the outside temperature and estimated comfort temperature. The second one is the separation of the data using the previously proposed comfort temperature as a dividing point. The other successful strategy is the recalibration of the adjusted PMV equation called, PMVnew. Based on the fact that humans have different biological strategies to deal with the heat and the cold, a separation between the two conditions is made. The adaptive comfort temperature equation is used for the separation. Separately calibrated equations perform better than those calibrated as universal equations. In total, five calibrated equations perform better than their precedents.

[1] Höppe, P., Improving Indoor Thermal Comfort by Changing Outdoor Conditions. Energy and Buildings, 1990. 15-16: p. 743-747. [2] Spagnolo, J. and R.d. Dear, A Field Study of Thermal Comfort in Outdoor and Semi-outdoor Environments in Subtropical Sydney, Australia. Building and Environment, 2003. 38(5): p. 721738. [3] Nikolopoulou, M. and K. Steemers, Thermal Comfort and Psychological Adaptation as a Guide for Designing Urban Spaces. Energy and Buildings, 2003. 35(1): p. 95-101. [4] Hoof, J.v., Forty years of Fanger’s model of thermal comfort: comfort for all? Indoor Air 2008. 18: p. 182-201. [5] Höppe, P., Different aspects of assessing indoor and outdoor thermal comfort. Energy and buildings, 2002. 34: p. 661-665. [6] Bruse, M. Simulating Human Thermal Comfort and Resulting Usage Patterns of Urban Open Spaces with a Multi-Agent System. in the 24th International Conference on Passive and Low Energy Architecture (PLEA). 2007. Singapore [7] Int-Hout, D., Thermal Comfort Calculations: A Computer Model. ASHRAE Transactions, 1990. 96(1): p. 840-844. [8] Chun, C., et al., Thermal Diary: Connecting Temperature History to Indoor Comfort. Building and Environment, 2008. 43: p. 877-885. [9] Chalfoun, N.V. Thermal Comfort Assessment of Outdoor Spaces Using MRT and Fish-eye Lens Photography of Architectural Scale Models: A Case Study of the “ARTS OASIS” Plaza at the University of Arizona, USA. in the 18th Conference on Passive and Low Energy Architecture.2001. Florianopolis, Brazil. [10] Caldieron, J.-M., et al. Statistical Model Evaluations and Calibrations for Outdoor Comfort Assessment in South Florida. in PLEA 2011: Architecture and Sustainability Development. 2010. Louvain-la-Neuve, Belgium. [11] Nicol, J.F. and M.A. Humphreys, Adaptive Thermal Comfort and Sustainable Thermal Standards for Buildings. Energy and Buildings, 2002. 34: p. 563-572. [12] Humphreys, M.A. and J.F. Nicol, The Validity of ISO-PMV for Predicting Comfort Votes in Everyday Thermal Environments. Energy and Buildings, 2002. 34: p. 667-687.

6. FUTURE WORKS The calibrations are performed on data collected in the summer and fall. Therefore, they cannot be used as universal assessment. More studies need to be conducted with more data that cover a wider range of climatic conditions, clothing, and activities. Furthermore, the equations need to be validated using a different set of data. In addition, the research team plans to study possibility of the dynamic assessment, which requires detailed measurements. For instance, we found that the spot measurements of skin and clothing temperatures do not yield agreeable results when used in the PMV equation. Those temperatures are estimated through iterative calculations to find convergences. Thermographic measurements may yield better estimates of the average temperatures. The collected data can be used to study different aspects of the outdoor comfort, for example, differences in the thermal sensation among genders, age groups, places of origin, and average duration of outdoor stay.

7. ACKNOWLEDGEMENTS This research project was funded by the ARCC and FAU. Associate Professor Aron Temkin has agreed to match the ARCC’s funding. Gerard Clinton, the Assistant Dean, has been supervising the funding transfer and budget management. Nima Upadhayay, Michael Goodwin and Patrick Kondziola assisted with the surveys.

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Proposal of an outdoor thermal comfort index: empirical verification in the subtropical climate Leonardo Marques MONTEIRO, Marcia Peinado ALUCCI Department of Technology, Faculty of Architecture and Urbanism, University of Sao Paulo, Brazil ABSTRACT: This paper presents a research that proposes a thermal comfort index, allowing the prediction of thermal adequacy in urban outdoor spaces. It also considers an empirical verification of the proposed model in subtropical climate conditions. The method adopted is experimental inductive, by means of field research of a total of ninety-eight micro-climatic situations and over two thousand and five hundred applied questionnaires of thermal sensation perception and preference. Deductive method is also applied, by means of regression analysis, considering seventy-two different micro-climatic conditions. The results are verified by empirical research considering the results from twenty-six different micro-climatic conditions gathered in different urban situations from the previous survey. The significance of the results is considered through comparison with the results obtained by simulation of different predictive models and their respective indexes. The results from the proposed equation, compared with those from the others predictive models, showed that, for the specific subtropical microclimatic conditions, they present better correlations with the data gathered. Keywords: outdoor thermal comfort, microclimate, subtropics

1. INTRODUCTION This paper presents a research that proposes a thermal comfort index, allowing the verification of the thermal adequacy of outdoor spaces in the subtropics. The method adopted is experimental inductive, by means of field research of microclimatic variables and subjective answers, and deductive, by means of regression analysis. The significance of the results is verified by comparison with the ones obtained in different urban situations from the previous ones.

2. PREDICTIVE MODELS This study considered twenty-two predictive models and their indexes. They will be here briefly presented in order to perform later correlation of their results with the results of the empirical research. Houghten et al. [1], of ASHVE laboratories, propose, in 1923, the Effective Temperature (ET), as determined by dry and wet bulb temperature and wind speed. Vernon & Warner [apud 2], in 1932 propose the Corrected Effective Temperature (CET) substituting dry bulb temperature with globe temperature. Siple & Passel [3], in 1965, develop the Wind Chill Temperature (WCT) from the data obtained with experiences in Antarctica. Belding & Hatch [4], in 1965, propose the Heat Stress Index (HSI), relying on a thermal balance model with empirical equations for each exchange. Yaglou & Minard [5], in 1957, propose the Wet Bulb Globe Temperature (WBGT). ISO 7243:1989 [6] gives an alternate equation for situations under solar radiation. Gagge [7], in 1967, presents the New Standard Effective Temperature (SET*), defining it as the air temperature in which, in a given reference environment, the person has the same skin temperature (tsk) and wetness (w) as in the real

environment. Givoni [8], in 1969, proposes the Index of Thermal Stress (ITS), which considers the heat exchanges, metabolism and clothes. Originally, it did not consider the radiation exchanges. Masterton & Richardson [9], in 1979, propose the Humidex, an index calculated based on air temperature and humidity. It is used by the Environment Canada Meteorological Service to alert people of the heat stress danger. Jendrizky et al. [10], in 1979, developed the Klima Michel Model (KMM). It is an adaptation of Fanger’s model [11], with a short wave radiation model, computed in the mean radiant temperature.Vogt [12], in 1981, proposes the evaluation of thermal stress through the required sweat rate (Swreq). This index was adopted by ISO 7933:1989 [13]. Dominguez et al. [14], in 1992, present the research results of the Termotecnia Group of Seville University, also based on Vogt [12]. The authors accept low sweat rates according to the conditioning required. Brown & Gillespie [15], in 1995, propose an outdoor Comfort Formula based on thermal budget (S) with particularities in its terms. Aroztegui [16], also in 1995, proposes the Outdoor Neutral Temperature (Tne), based on Humphreys [17] and taking into account the solar radiation and air speed. Blazejczyk [18], in 1996, proposes the Man-Environment Heat Exchange model (Menex), based on thermal balance. The author proposes three criteria, which are supposed to be considered as a whole: Heat Load (HL), Intensity of Radiation Stimuli (R’) and Physiological Strain (PhS). He also proposes the Subjective Temperature Index (STI) and the Sensible Perspiration Index (SP). DeFreitas [apud 19], in 1997, presents the Potential Storage Index (PSI) and the Skin Temperature Equilibrating Thermal Balance (STE), both using the Menex Model. Höppe [20], in 1999, defines the Physiological Equivalent Temperature (PET) of a given environment as the equivalent temperature to air temperature in which,

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in a reference environment, the thermal balance and the skin and core temperatures are the same of that found in the given environment. Givoni & Noguchi [21], in 2000, describe an experimental research in a park in Yokohama, Japan, and propose the Thermal Sensation Index (TS). Bluestein & Osczevski [22], in 2002, propose the New Wind Chill Temperature (NWCT), through a physical modelling of a face exposed to wind. Nikolopoulou [23], in 2004, presents the works developed by the project Rediscovering the Urban Realm and Open Spaces (RUROS), proposing the actual sensation vote (ASV).

3. METHODS 3.1. Empirical data The procedures were done following guidelines and data from [24, 25, 26, 27, 28]. On the field researches, seventy-two different micro-climatic scenarios were considered and one thousand and seven hundred and fifty questionnaires were applied during summer and winter of two consecutive years, in the city of Sao Paulo, Brazil. The procedures are briefly presented in the following paragraphs. For the measurements and application of questionnaires, three bases (Figure 1) were set: the first one under open sky, the second one under a tensioned membrane structure, and the third one shaded by trees. In each one of the three bases, micro-climatic variables (mean radiant temperature, air temperature, air humidity and wind speed) were measured and a hundred and fifty people answered a questionnaire, in six different hours of the day. These people came from different regions of Brazil. Further studies will consider not only the results from acclimatized ones, but also comparatively the results from those who were not acclimatized.

parameters (global radiation and wind speed). The equipment used in each base was the following. Under open sky: meteorological station ELE model EMS, data logger ELE model MM900 EE 475-016. Shaded by trees: meteorological station Huger Eletronics model GmbH WM918 and personal computer for data logging. Under tensioned membrane structure: station Innova 7301, with modules of thermal comfort and stress, and data logger Innova model 1221. At 10m high: meteorological station Huger Eletronics model GmbH WM921 and a piranometer Eppley. In each base, globe temperature was also measured through 15cm grey globes and semiconductor sensors, storing the data in Hobo data loggers. The measurements were done in intervals of one second, and the storage was done in intervals of one minute, considering the average of measurements. The limits in which the empirical data were gathered are: air temperature (ta) = 15°C~33°C; mean radiant temperature (mrt) = 15°C~66°C; relative humidity (rh) = 30%~95%; wind speed (va) = 0,1m/s~3,6m/s. It should also be mentioned that, although it is not a limiting factor for normal situations, the maximum and minimum clothing thermal insulation values found were 0,3 and 1,2 clo, with mean values between 0,4 and 0,9 clo. Considering the Typical Reference Year (TRY) [29] for Sao Paulo, the ranges presented represent 92% of the general climatic situations during day time. On the other hand, if it is necessary to make an extrapolation, it must be done carefully and would better be object of further researches. 3.2. Modelling The multiple linear regression to be presented was obtained considering the data from the seventytwo microclimatic situations, regarding the application of one thousand and seven hundred and fifty questionnaires. tsp= -3,557 + 0,0632 • ta + 0,0677 • mrt + + 0,0105 • ur - 0,304 • va

[1]

with: r= 0,936; r2= 0,875; r2aj= 0,868; se= 0,315; P< 0,001. where: tsp= thermal sensation perception [dimensionless], ta = air temperature [oC], mrt = mean radiant temperature [oC], rh = relative humidity [%], v = air velocity [m/s] Figure 1: three bases: the first one under open sky, the second one under a tensioned membrane structure and the third one shaded by trees.

The questionnaire considered questions of personal characteristics (sex, age, weight, height), acclimatization (places of living and duration) and subjective responses (thermal sensation, preference, comfort and tolerance). Pictures were taken of everyone who would answer the questionnaire, in order to identify clothing and activity. A forth base, at 10m high, was set for measuring meteorological

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Considering the thermal sensation perception (tsp), following the categories of the applied questionnaires, result from -0,5 to 0,5 means neutrality; from 0,5 to 1,5 means warm; from 1,5 to 2,5 means hot; above 2,5 means very hot; from -0,5 to -1,5 means cool; from -1,5 to -2,5 means cold; and below -2,5 means very cold. Table 1 presents a statistic resume of the constant and the four dependent variables and Table 2 presents the analysis of variance.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 1: Statistic summary of the constant and the four dependent variables

ct ta mrt rh va

c

-3,557 0,0632 0,0677 0,0105 -0,304

se t 0,249 -11,17 0,0143 3,796 0,011 -2,803 0,00305 2,220 0,0053 12,861

p VIF <0,001 <0,001 2,101 <0,001 1,135 <0,001 2,089 <0,001 1,915

where: ct= constant, c = coefficient, se= standard error, t= statistical test t, p= significance, VIF= variance inflation factor. Table 2: Analysis of variance

Regression Residual Total

DF 4 67 71

SS MS F p 46,667 11,667 117,44 <0,001 6,656 0,0993 53,323 0,751

where: DF= degrees of freedom, SS= sum of squares, MS= mean square, F= statistical test F, p= significance. Monteiro & Alucci [30], reviewing the state of the art of outdoor thermal comfort modelling researches, observe that there is a tendency to use equivalent temperatures instead of interpretative ranges, since an equivalent temperature itself, without an interpretative range, would give a notion of the thermal sensation, taking into account a reference environment. In this research, in order to propose an equivalent temperature model, the following assumptions to the reference environment where done: mrt = ta; rh=50% and va=0 m/s. Considering these assumptions, the relationship between the air temperature of the reference environment and the thermal sensation perception is the following: ta,re = 23,395 + 7,639 • tsp

range, since the intuitive interpretation is only possible after the exposition to several environments and their respective equivalent temperatures. In the Discussion topic of this paper interpretative ranges for the Temperature of Equivalent Perception (TEP) will be proposed. Considering the applicability of the proposed equation, the limits in which the Temperature of Equivalent Perception (TEP) is valid are the ones verified for the empirical research. Table 3 presents the limits of the microclimatic variables, in which TEP is based. Further studies to be developed, with more comprehensive empirical data, would test the validity of the results beyond those limits. Table 3: Limit values for microclimatic variables

variable ta (oC) mrt (oC) rh (%) va (m/s) TEP (oC)

min

15,1 15,5 30,9 0,1 13,7

max

33,1 65,5 94,7 3,6 45,3

Table 4 presents the interpretative ranges for the Temperature of Equivalent Perception (TEP), considering the results found in the empirical researches. Table 4: Temperature of Equivalent Perception (TEP)

TEP (oC) > 42,5 34,9 ~ 42,4 27,3 ~ 34,8 19,6 ~ 27,2 12,0 ~ 19,5 4,4 ~ 11,9 < 4,3

Sensation very hot hot warm neutrality cool cold very cold

[2]

where: ta,re = air temperature of the reference environment [oC], tsp = thermal sensation perception [dimensionless]. By equations 1 and 2, the following equation is proposed, where TEP stands for the proposed Temperature of Equivalent Perception, in oC.

4. VERIFICATION The results presented are verified by empirical research considering the results from twenty-six different micro-climatic conditions gathered in different urban situations from the previous survey. Figure 2 present these different urban configurations.

TEP = -3,777 + 0,4828 • ta + 0,5172 • mrt + + 0,0802 • rh - 2,322 • va [3] The Temperature of Equivalent Perception (TEP) of a given environment can be defined as a thermal sensation scale which presents values numerically equivalent to those of the air temperature of a reference environment (mrt=ta, rh=50%, and va=0) in which the thermal sensation perception is the same to the one verified in the given environment. Following equation 2, one may observe that the air temperature of neutrality, in the case of a reference environment, is approximately equal to 23,4°C. Yet the advantage of equivalent temperatures is the intuitive interpretation of their values, it is also interesting to provide a interpretative

Figure 2: three bases for the verification of the results: the first one in an urban canyon, the second on under open sky, and the third one shaded by trees.

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Three criteria were established for comparing the simulation results with the new field research results aiming to verify the significance of the results provided by the new proposed predictive model. The first criterion is the correlation between the results of the model parameter and the results of the thermal sensation responses obtained in the field study. The second criterion is the correlation between the results of the index and the results of the thermal sensation responses obtained in the field study. The last one is the percentage of correct predictions. Concerning the indexes based on equivalent temperatures, the criterion for interpretation of the indexes used was the one by De Freitas [19]. Yet the author proposes this one only for effective temperatures, it was used for other equivalent temperatures because no other references were found; except for STI, for which was used Blazejczyk [18]. All the criteria are based on results concerning new empirical field researches, performed during summer and winter, in three different locations, in another neighbourhood of Sao Paulo, using the same procedures established before, and considering twenty-six new micro-climatic scenarios and the mean thermal sensation responses for each one of this scenarios (eight hundred and fifty eight applied questionnaires). Aiming better results to the specific evaluation of open spaces of Sao Paulo, a calibration was performed in order to fit the results from the simulations to the results found in the empirical researches. In order to do so, each index was linguistically compared to seven values (the same used in the field researches): three positive ones (warm, hot, very hot), three negative ones (cool, cold, very cold) and one of neutrality (negative values do not apply for models that consider only hot environments). The calibration was done through iterative method, changing the range limits of each index in order to maximize the correlation between its results and those found in the empirical researches. The calibration could be done, also iteratively, to maximize the percentage of correct predictions. However, it was assumed that is more important to assure the maximization of the correlation between the results of the index and those from empirical data, once this correlation expresses the tendency of correctly predicting other situations.

5. RESULTS Table 4 presents the final results considering the comparison criteria presented. This table presents the correlation modules between field study results and simulation results, without and with the calibration process presented. In the table: C= Correlation with the model parameter; Co= Correlation with the original index without calibration; Po= Percentage of correct predictions without calibration; Cc= Correlation with the index with calibration; and Pc= Percentage of correct predictions with calibration.

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Table 4: Correlation between new field study and simulation results from different predictive models

Index ET* CET* OT EOT* WCTI HSI WBGT SET* ITS HU PMV Swreq W Swreq’ S’ Tne HL PhS R’ STI SP ECI PSI STE PET TS NWCTI ASV TEP

C 0,73 0,85 0,66 0,61 0,70 0,74 0,83 0,70 0,75 0,56 0,65 0,82 0,77 0,81 0,84 0,71 0,86 0,78 0,74 0,82 0,76 0,67 0,81 0,68 0,75 0,63 0,58 0,76 0,85

Co 0,66 0,81 0,62 0,64 0,60 0,66 0,66 0,65 0,55 0,64 0,60 0,67 0,61 0,76 0,78 0,43 0,80 0,66 0,74 0,79 0,67 0,75 0,61 0,54 0,67 -

Po 23% 41% 34% 45% 14% 14% 11% 43% 25% 39% 45% 59% 36% 41% 52% 18% 14% 52% 50% 27% 27% 32% 32% 15% 30% -

Cc 0,74 0,83 0,72 0,76 0,64 0,69 0,80 0,69 0,75 0,57 0,78 0,83 0,66 0,85 0,76 0,70 0,86 0,78 0,56 0,78 0,73 0,76 0,79 0,77 0,78 0,72 0,59 0,78 0,86

Pc 55% 66% 55% 48% 35% 48% 55% 59% 55% 43% 57% 57% 53% 64% 52% 57% 68% 55% 24% 39% 55% 53% 41% 41% 52% 48% 30% 34% 66%

6. DISCUSSION Considering Table 4, one may observe that the best results without calibration are provided by the Potential Storage Index (PSI), calculated using the MENEX model proposed by Blazejczyk [18]. This index presented correlations of 0,86 and 0,76; respectively for its model parameter and its original index. The percentage of correct predictions, also without calibration was one of 41%, one of the highest among the original indexes. Following Table 4, one may affirm that, before the proposal of the Temperature of Equivalent Perception (TEP), for the specific case of evaluating outdoor spaces on the subtropics, the best index would be the Perceived Equivalent Temperature, calculated using the MEMI model proposed by Hoppe [20]. Although it provided poorer results considering the first interpretative ranges, with the calibration process the new ranges provided the best results among the studied indexes: correlations of 0,86 and 0,68; respectively for the model parameter and the calibrated index. The percentage of correct predictions, with calibration, was 68%. Keep on following Table 4, one may observe that the results of the proposed Temperature of Equivalent Perception (TEP) provides better results than all the other indexes, even when compared with the results form the calibrated indexes. Its

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

correlations are of 0,85 for the model parameter and 0,85 for the index. The percentage of correct predictions achieved 96%, the highest among all the results. In the topic about modelling, it was argued that the advantage of equivalent temperatures is the intuitive interpretation of their values. On the other hand, it is also interesting to provide an interpretative range, since the intuitive interpretation is only possible after the exposition to several environments and their respective equivalent temperatures. One may observe that the criteria used to evaluate the model predictions allow successive verifications. The first correlation verifies the possible potential of the model. In other words, it verifies the sensibility of the model, showing how well the model parameter results vary in function to variations of thermal responses. The second correlation does the same, but specifically with the interpretation criteria of the indexes. The final criterion gives the percentage of correct predictions, telling how well the model is performing. Considering the calibration, we can observe that it provides better correlation with the new empirical data gathered and consequently greater percentage of correct predictions. Considering the results found, it is more interesting to use a model with a better first correlation (the correlation between the model parameter and the field subject responses) than a one with a greater percentage of correct predictions but with a poor first correlation, because a good first correlation means that the models, once calibrated with empirical data, has a good potential to correctly predict the thermal sensations. As one may see, the Temperature of Equivalent Perception (TEP), proposed in this work, presents the highest correlation between the model parameter and the field subject responses, leading also to the highest correlation between the index and the field subject responses. Finally, it presents also the best results in term of percentage of correct predictions. One may also notice that, before proposing the Temperature of Equivalent Perception, the best results would be given by the Potential Storage Index (PSI), calculated using the MENEX model proposed by Blazejczyk [18], or by the Physiological Equivalent Temperature (PET), calculated using the MEMI model proposed by Hoppe [20]. One may see that both indexes are estimated by means of a thermophysiological balance model, which needs several iterations to provide reliable results. The Temperature of Equivalent Perception (TEP) not only presented as good results as those compared to the empirical data gathered, but also provides a simpler model to estimate outdoor thermal comfort, since it relies on only one multiple linear equation.

7. FINAL CONSIDERATION The research provided a simple, easy-to-use and reliable index to assess thermal comfort in outdoor spaces in a subtropical climate. Thus, the main contribution of this paper is to provide a thermal comfort index which can be properly used for predicting thermal comfort in outdoor spaces in a subtropical climate. The experimental comparative

study of different outdoor thermal comfort predictive models allowed the verification of the results. Comparing the results from the equation generated from multiple linear regression analysis to the ones from the predictive models, one may observe that the equation found, which culminated in the proposal of the Temperature of Equivalent Perception, presents good correlations with the data gathered in new scenarios.

8. ACKNOWLEDGEMENTS The authors would like to thank the Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), for the financial support in this research.

9. REFERENCES [1] Houghten, F.C.; Yaglou, C.P. Determining lines of equal comfort. ASHVE Transactions, 29, 1923. [2] Williamson, S. P. (coord.). Report on wind chill temperature and extreme heat indices: evaluation and improvement projects. Washington: OFCMS Supporting Research, 2003. [3] Siple, P. A.; Passel C. F. Measurements of dry atmospheric cooling in subfreezing temperatures. Proceedings of the American Philosophical Society, 89 (1), p.177-199, 1945. [4] Belding, H. S.; Hatch, T. F. Index for evaluating heat stress in terms of resulting physiological strain. Heating, Piping, Air Conditioning, 27, p.129-42, 1955. [5] Yaglou, C. P.; Minard, D. Control of heat casualties at military training centers. A.M.A. Archives of Industrial Health, 16, p. 302-16, 1957. [6] International Organization Standardization. ISO 7243. Hot environments: estimation of the heat stress on working man, based on the WBGT-index (wet bulb globe temperature). Genève: ISO, 1989. [7] Gagge, A. P.; Stolwijk J. A. J.; Hardy, J. D. Comfort and thermal sensations and associated physiological responses at various ambient temperatures. Environ. Res., 1, p. 1-20, 1967. [8] Givoni, Baruch. Man, climate and architecture. New York: John Wiley & Sons, 1969. [9] Masterton, J. M.; Richardson, F. A. Humidex: a method of quantifying human discomfort. Environment Canada, CLI 1-79. Ontario, Downsview: Atmospheric Environment Service, 1979. [10] Jendritzky, Gerd et al. Klimatologische Probleme – ein einfaches Verfahren zur Vorhersage der Wärmebelastung, in Zeitschrift für angewandte Bäder und Klimaheilkunde. Freiburg, 1979. [11] Fanger, P. O. Thermal comfort: analysis and application in environment engineering. New York: McGraw Hill, 1970. [12] Vogt, J.J. Ambiances thermiques. In: Scherrer, J. et al. Précis de physiologie du travail, notions d’ergonomie, Masson, 2ème édition, 217-263 1981.

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[13] ISO. ISO 7933. Hot environments: analytical determination and interpretation of thermal stress using calculation of required sweat rate. Genève: ISO, 1989. [14] Dominguez et al. Control climatico en espacios abiertos: el proyecto Expo'92. Sevilla: Universidad de Sevilla, 1992. [15] Brown, Robert D.; Gillespie, Terry J. Microclimatic landscape design: creating thermal comfort and energy efficiency. New York: John Wiley & Sons, 1995. [16] Aroztegui, José Miguel. Índice de Temperatura Neutra Exterior. In: Encontro Nacional Sobre Conforto No Ambiente Construído (ENCAC), 3, 1995, Gramado. Anais... Gramado: ENCAC, 1995. [17] Humphreys, Michael A. Field studies of thermal comfort compared and applied. BRE Current Paper, 75/76, London, 1975. [18] Blazejczyk, Krysztof. Menex 2002. http://www. igipz.pan.pl/klimat/blaz/menex.htm. 2002. Visited in 24/04/2004. [19] Blazejczyk, Krysztof; Tokura, Hiromi; Bortkwcz, Alicja; Szymczak, W. Solar radiation and thermal physiology in man. In: International Congress of Biometeorology & International Conference on Urban Climatology, 15, 1999, Sydney. Selected Papers from the Conference... Geneva: World Meteorological Organization, p. 267-272, 2000. [20] Höppe, Peter R. The physiological equivalent temperature: a universal index for the biometeorological assessment of the thermal environment. Int. J. Biomet., 43, p. 71-75, 1999. [21] Givoni, Baruch; Noguchi, Mikiko. Issues in outdoor comfort research. In: Passive And Low Energy Architecture, 17, 2000, Cambridge. Proceedings... London: J&J, p. 562-565, 2002. [22] Bluestein, M.; Osczevski, R. Wind chill and the development of frostbite in the face. Preprints, 15th Conference on Biometeorology and Aerobiology, Kansas City, MO: Amer. Met. Soc., p. 168-171, 2002. [23] Nikolopoulou, Marialena (org). Designing Open Spaces in the Urban Environment: a Bioclimatic Approach. Atenas: CRES, 2004. [24] ASHRAE. Handbook of fundamentals. Atlanta: ASHRAE, 2005. [25] ISO. ISO 7726. Ergonomics: instruments for measuring physical quantities. ISO: Genève, 1998. [26] ISO. ISO 9920. Ergonomics of the thermal environment: estimation of the thermal insulation and evaporative resistance of a clothing ensemble. ISO: Genève, 1995. [27] ISO. ISO 10551. Ergonomics of the thermal environment: assessment of the influence of the thermal environment using subjective judgment scales. ISO: Genève, 1995. [28] ISO. ISO 8996. Ergonomics: metabolic heat production. ISO: Genève, 1990. [29] Goulart, S. et al. Climatic data for energetic evaluation of buildings in fourteen Brazilian cities. Florianópolis: UFSC, 1998.

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[30] Monteiro, L.M.; Alucci, M.P. Outdoor thermal comfort: numerical modelling approaches and new perspectives. In: Passive And Low Energy Architecture, 22, 2005, Beirut. Proceedings... 2005.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. ISBN xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

Evaluation of comfort conditions and sustainable design of urban open spaces in Crete MARIANNA TSITOURA1, MICHAILIDOU MARINA2, THEOCHARIS TSOUTSOS3

Department of Environmental Engineering, Technical University of Crete, GR-73100 Chania, Greece

ABSTRACT: The thermal environment in outdoor public spaces and their use is highly relevant to individuals’ thermal comfort perception. Since climatic conditions directly affect the use and activities of outdoor spaces, they should be taken into account when designing public spaces. Especially in Southern Europe, due to the extended use of outdoor spaces during summertime where the urban heat island phenomenon is present, a more sustainable design is very critical for their viability. This present paper reveals the strong relationship between the microclimate and the outdoor comfort conditions through field surveys conducted in four different urban open spaces in Crete. Thermal indices like PMV (Predicted Mean Vote), PET (Physiologically Equivalent Temperature) and SET (Standard Effective Temperature), WBGT (Wet bulb globe temperature)are used to evaluate the assessment of urban microclimate and then are compared in order to find the most suitable for the Mediterranean microclimate. In this way every designer can simply affect the sustainability of the urban open place with the control of the microclimatic conditions into it and can easily predict the levels of comfort of his proposal. The deviations of these microclimate factors that are proved to affect the individual thermal comfort, in the Mediterranean climate of Crete, are simulated using the numerical microclimate model ENVI-met (Bruse and Fleer 1998). ENVI-met uses data from the area design, vegetation, climate, materials and translates them into microclimate maps of present and future. In this way develops the ability to the designer to evaluate with high accuracy the comfort conditions of every outdoor design and its effect on the surrounding microclimate. Field measurements on a central park of Chania one day per month validates the accuracy of the simulation using ENVI-met, afterwards several design and vegetation scenarios are tested in order to conclude in the most viable in terms of comfort solution. The aim of this study is not only to evaluate the most suitable value of every microclimatic factor for the individual perception of comfort so as to provide a specialized model of comfort in the Mediterranean areas but also to find the way for achieving the desired microclimatic conditions through a proposed sustainable design. Keywords: Outdoor comfort; microclimatic monitoring; field surveys; sustainable design

1. INTRODUCTION One of the most fundamental issues in the structure and use of every type of city is the urban open space. Its type and use is directly affected by the habitants and vice versa the habitants quality of life and social status is related with the open urban space design [1,2]. The major factor that determines the quality of the open urban spaces is the climate conditions that occur in the micro scale environment [3]. Humidity levels, especially in hot climates and coastal regions [4,5] the mean radiant temperature as well as the cold air supply within the urban space affect the health [6] and well being of the citizens therefore the development of the whole city area in several ways, affect on tourism [7,8], affect on the local market, affect on the residences [9]. Especially in islands this relationship is more evident because the majority of the open space is in the form of a large central square in the city center [10]; in this way every intervention to the open space may have obvious beneficial results in the sustainability of the whole urban system [11]. With the study of the severable microclimatic factors in relation with the comfort factors of people using them can determine the basic parameters of sustainable design [12]. This realization, in fact provides the basic cause for further study about the determination of these parameters [13-15]. The initial findings of the current research study aims to implement additional information about the correlation between the microclimatic characteristics of open urban spaces and the comfort votes of people using them [16].

One of the fundamental issues in human comfort is the human biometeorology. Human biometeorology issues are studied since 1750 and several indices are developed in order to explain the energy that is exchanged between the human body and the outdoor environment. Some of these indices are based in two parameters and some include a total exchange model. The most reliable indices are the Standard Predictive Index of Human Response approach [17], and Out_SET* [18] which combine the manenvironment heat exchange (MENEX) model [19], the Thermal Environmental Index [20]. In this context, microclimatic conditions have begun being viewed as integral to the success of an open space as they determine critical parameters for the use of outdoor spaces in the urban environment. [21,22]. This paper goes further, examining the way microclimatic conditions, such as air temperature, solar radiation, relative humidity and wind speed and direction, in relation with psychological factors affect the use of urban open spaces in a Mediterranean island climate, concentrating on the surveys carried out in four different cities in Crete, Greece [23]. The aim of the paper is to provide the basic rules which can be used for a sustainable design of open urban spaces in every type of Mediterranean island and secondly to organize the basic steps and method for achieving that. These basic rules with the use of simulation results are implemented to a central park in Crete, through this way, can be calculated the exact impact that the microclimate can have in the comfort levels in every point of the park and finally end to a more sustainable design proposal.

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

2. METHOD In order to ensure the sustainability of the design processes this survey is divided in two basic steps. In the beginning surveys were conducted in four different sites in Crete in order to determine the comfort levels of the open urban spaces in Crete. A questionnaire survey and physical measurements at the same time was used to assess the thermal comfort of visitors. The questionnaire included questions about comfort, physical evidence and psychological evidence and the microclimatic data were measured by one weather station which was placed in the middle of every square and several portable sensors for more detailed data of the exact place of every interview. Afterwards with the actual sensation votes and the measured data is enabled the calculation of several outdoor climate indices and the selection of the more representative of the actual votes. This index is simulated using the software Envimet 3.1 after its validation of the data produced for the summer months June to September. Because the comfort votes are found to be very low during the summer period and not so low during winter, the survey is focused on the summer period. To conclude after the simulation of the selected site without any intervention, a more sustainable design is proposed and the new comfort levels are compared with the existing ones.

3. SURVEY 3.1. Interviews In order to examine the variety of the several urban climates within Crete all the four sites that were selected enhance different characteristics considering their vegetation, their location and their use. The first one is within the historical center of Chania, on the coastal zone, the second one is between the shopping center and the port in Rethymnon the third one is in the shopping center of Heraklion and the fourth is located on a mountainous area near Heraklion called Archanes. In each of the four cities participating in the project two case studies, one in the winter (February 2009) and one in the summer (July 2009), were conducted from 10 am to 4 pm. Each site was monitored for a representative day each season; the climate conditions of the days of the survey were afterwards compared to the mean climatic conditions at every city for this season so as to confirm the effectiveness of the data measured. The field surveys involved detailed microclimatic monitoring with the use of a portable mini-weather station, with sensors conforming to ISO 7726 [24], while people were studied in the open space environment through structured interviews and observations, to evaluate the comfort conditions in a scale of five levels from very bad (-2) to very good (+2) their experience and their perception of the environment. The weather station, which was put in the middle of every square, saved values of air o temperature ( C), air velocity (m/s), relative humidity 2 (%) and sun radiation (W/m ) every 5 mins whereas several values of portable sensors were saved on the

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place and time of the interview (one questionnaire per person). All the thermal indexes calculated were based in the values measured and the answers given by every person separately. The questionnaires were completed only by the people who actually used the squares and stayed in them at least for 5 mins. Subject’s thermal sensation and comfort vote were recorded by face-to-face interview while subject’s demographic background, clothing and activities were recorded by observation. The results of the questionnaire survey were correlated with the micrometeorological data. During the questionnaire survey the people involved were carefully selected in order to contain all the different age groups and sexes present and also the special characteristics and use of the different squares. This paper focuses on issues related to the use of space, as opposed to people’s evaluation of the comfort conditions. 3.2. Thermal indexes The thermal comfort can be described with the use of certain indices. Some of them are used in the current study : -WBGT takes only climatic data into account such as air temperature, radiant heat, solar radiation, air movement -PMV has solid base in the indoor environment but takes into account relevant factors and the affect thermal sensation -PET and out SET are for outdoor environments. PET does not calculate individual parameters and out SET takes personal parameters for one standard type of person. The ISO 7730 defines thermal conditions of outdoor environment in which the probability of a negative vote is minimized. The index ―Predicted Mean Vote – PMV‖ and the index ―Predicted Percentage Dissatisfied‖ are based on ISO 7730 and are taking into account the climatic parameters in conjunction with the relevant factors affecting the thermal sensation of each respondent (clothing, metabolic rate, eating or drinking) [25]. The PMV-index describes the comfort levels with the prediction of the possible votes taking into account meteorological factor in combination with human biometeorology values [26]. The value of the index is between -7 which means too cold and +7 which means too hot and the value of zero represents the comfort vote. With this scale the closest the value of the PMV index is to 0 the better are the comfort levels for the human. Still this index cannot take into account the psychological factors described and that is why there are certain differences of the value of the PMV and the real votes on the field surveys We can calculate the PMV values with the formula [25]: -0.036*M + 0.028)*[M-W)-H-Ec-Cres- Eres] PMV= (0.303*e

M:Metabolic rate. The rate of transformation of chemical energy into heat and mechanical work by aerobic and anaerobic activities within the body [W/m 2] W: Effective mechanical power [W/m 2] Η: Dry Heat Loss. Heat loss from the body surface through convection, radiation and conduction [W/m2] Εc: Evaporative heat exchange at the skin, when the person experiences a sensation of thermal neutrality. [W/m 2] Cres: Respiratory convective heat exchange [W/m2]

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011 th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Εres: Respiratory evaporative heat exchange [W/m2]

For the calculation of PMV used the software Envimet 3.1. Common microclimatic data with the PMV (Predicted Mean Vote) require two other indexes: PET (Physiologically Equivalent Temperature) and out SET (Standard Effective Temperature) [27]. All those thermal indices are well documented and include important meteorological and thermophysiological parameters so as to define the total o comfort [28]. The scale that are measured is in C but the parameters required in the model are both climatic (air temperature, humidity, radiation environment, wind speed and direction) but also physical characteristics of every interviewee (age, sex, weight, height, clothes, metabolism rate) [29]. A full application of these thermal indices on the energy balance of the human body gives detailed information about the effect of the thermal environment on every human. For the calculation of PET and out SET it is used the Rayman model designed by Matzarakis [6,8,29] for every single interview. According to the results of mean values of these calculations, the mean PET value during summer is on the ―too hot‖ group whereas the mean PET value during winter is on the ―comfort‖ group. The same applies also to the out SET values with a slight difference in the summer. The PET values are recorded relatively high in summer due to the high sun radiation levels. All the indices were calculated for all the squares both in summer and winter and the results of their comparison with the actual votes are quite similar. Figure 1 shows the exact value of each one of those indices in summer and winter for the hours of the interview, only for Talo square in Chania. From the comparison of the indices with the actual sensation votes can be assumed that: - out SET index is directly affected by the solar environment that is why appears so unstable - WBGT index is quite close to the air temperature and cannot describe at all the comfort levels - PMV index, cannot describe the comfort during summer but it can predict the increase or the fall of the comfort votes quite realistically After the linear regression of each one of these indexes with the actual sensation votes from the interviews of all the squares is found that the PMV index can better predict the comfort votes with the implication of the model : ASV = PMV x 0.16 + 0.22 2 (R = 0.72). Figure 1: Thermal indices value for Talo square in Chania for winter and summer

4. SIMULATION USING ENVIMET 3.1 4.1. Validation of Envimet 3.1 ENVI-met uses data from the area design, vegetation, climate, materials and translates them into microclimate maps of present and future. In this way the designer obtains the ability to evaluate with high accuracy the comfort conditions of every outdoor design and its effect on the surrounding microclimate. Field measurements on a central park of Chania, one day per month validates the accuracy of the simulation using ENVI-met. Several design and vegetation scenarios are tested in order to conclude in the most viable in terms of comfort solution. There have been some recent studies using ENVI-met to simulate the effect of urban vegetation on microclimate [30-35]. In this study, simulation software ENVI-met is used, as a three-dimensional numerical model designed to simulate the surface-plant-air interactions in urban environment in a microclimate scale, with a typical resolution of 0.5 to 50m in space and 10 seconds in time [36]. Typical areas of applications are Urban Climatology, Architecture, Building Design, and Environmental Planning and so on. Although it is not open source, ENVI-met is a freeware program based on different scientific research projects under constant development [36]. This is a parametric study based on typical Mediterranean island urban park morphology. A layout plan based on one central park in Chania in Crete, Greece is chosen. The park is situated in the center of the city and is surrounded by high traffic roads. Despite the high density of the urban environment and the large open space that it covers 2 (20.000 m ), the park is not used extensively neither by the pedestrians nor by people who want to relax. Although it has recently been designed and enhances several kinds of uses (pond, playground, benches etc), it seems quite deserted. Even one refreshment kiosk that was inside the area of the park is closed. Firstly Envimet 3.1 is validated with the comparative study of real time weather data obtained with measurements within the park for 8 hours every month from May to November, with the simulation data produced by Envimet 3.1 for the same hours and days of the measurements (Fig.2). In this validation Envimet is found to be quite accurate in simulating urban microclimate parameters. Especially for the factors of air temperature and relative humidity, which are the two factors that directly affect comfort, the results from the simulation were quite representative of the actual values. After the validation for the accuracy of the data produced as well as the comparison of the index PMV as calculated with the use of Envimet with the actual sensation votes from on site interviews on four different open urban spaces in Crete, simulations are designed and run respectively to calculate the index of PMV and to evaluate the comfort conditions in the study area.

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Fig.2 : Comparison of simulation results with measurements in the park

Wind speed (m/s)

o

Temperature ( C)

Relative Humidity (%)

2

Solar Radiation (W/m )

In addition the paving materials inside the park are mostly concrete and paving blocks that cannot absorb any kind of heat or radiation and contribute to the low comfort levels of the park. Another factor that is not beneficial for the comfort is the small lake that is placed on the lowest level of the park and it is surrounded by non accessible areas. In this way the water which is beneficial to the comfort levels cannot reach the visitor who needs special attention in order to observe it. The primary design located another lake on the top level of the square (Fig. 4) but this lake was never filled with water. The proposed design focuses on simple changes that could easily be implemented. The greenery problem is solved with the planting of additional trees and the replacement of the ones that are quite narrow and without leave density. The extra trees are placed near the sitting areas in the centre of the park. Also the concrete and paving stones are replaced with planted bricks with light colour and sandy soil and the second lake is filled with water. The results from the simulation of the PMV of the proposal (Fig.5) are compared with the results of the current design of the park (Fig.4). As can be assumed the boosted greenery had various effect both on the areas close to them and as well contributed to the total microclimate change. The green areas were united and their effect on the comfort is multiplied. The concrete floors do not show any improvement for the PMV index but the simulation showed some improvement on the solar radiation and temperatures of the surface. From the comparison of the PMV of the proposal design with the current design in two points of the park (Fig.6) is obvious that with simple interventions the PMV index can change from 0.1 to 0.5 points in a scale of 6. This percentage of improvement is quite beneficiary to the sustainability of the whole park. The water surface contributes a lot to this improvement and actually gives to a large sitting area which was useless, the microclimate needed for thermal comfort. Figure 3 : The central park in Chania, Study area,

4.2. Proposal The current design of the park enhances different uses and levels. The problems in the design are mostly located in the cover materials that are used and also in the dispersion of trees and greenery. As is shown in figure 3, although in some points the trees are quite dense, mostly these areas have no benches or sitting infrastructure. The selection of the trees is also an important factor. All the trees planted are tall, characterized by low density and with canopy perimeter. This affects the kind of shadow they provide and their contribution in the protection of solar radiation. The trees are mostly located in the four entrances of the park and not so much in the middle of it and inside the park are no protected places to sit or relax.

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Point 1

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parko_JULY 14:00:00 04.07.2010 x/y cut at z= 4

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 4 :PMV of the current design

the study have been redesigned over the last three years, so can be assumed that the design solutions were made without any study of the comfort 1.4 conditions prevailing in them. This fact can boost the 1.9 2.4 basic purpose of this study as it is obvious that every 2.9 attempt of designing open urban space can take into 3.4 account the site specifications, the people habits and 3.9 parko_JULY 14:00:00 04.07.2010 the local weather parameters in order to assure that it 4.4 x/y cut at z= 4 4.9 will become a live open place of social interaction. 5.4 For the quantification of the comfort levels several 5.9 indices were calculated. Index Wet Bulb Globe Temperature finds great accordance with the air temperature but cannot predict successfully the comfort votes. Other indexes like PET and SET have taken personal factors into account but they don’t reflect in great accordance the vote for comfort of the interviews. The best fitted index is the Predicted PMV Value Mean Vote, as calculated by the Envimet software in 1.4 N relation with Botworld tool. 1.9 Taken into account the results from the 2.4 2.9 questionnaires a different urban park is selected in 3.4 order implement the findings and to evaluate the 3.9 improvement possibilities. This park is located in the 4.4 4.9 center of Chania and enhances different uses and 5.4 spaces. Live measurements for 5 months on the park 5.9 area in relation with simulations with Envimet 3.1 software provides the validation results needed for further research. After the validation of the software used, basic measures are proposed in order to improve the PMV index and furthermore the comfort levels of the square. The comparison of the proposal with the current design showed remarkable improvement about 15% better of the current state N only with simple changes in the green areas and pavement materials. For the effectiveness of this simulation results, further measurements are needed as well as a specialized analysis of full representation of climatic behavior of each month. This would assist the design of insular cities through the design of outdoor spaces and eventually the use of these spaces, by allowing for different activities to be carried out and social interaction to take place, giving life back to the islands open spaces. Ultimately, such systematic knowledge can contribute to the sustainable development of island communities of the future. PMV Value

Figure 5 : PMV of the Proposal design

50

60

70

X (m)

80

90

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110

120

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140

Fig.6 : Current and Proposal’s PMV value 50

60

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X (m)

80

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140

5. CONCLUSION This study is conducted in several different steps. The final goal was to define the basic parameters that affect the comfort levels on open urban spaces in Mediterranean areas and to implement a simple design proposal to justify the possible change in the sustainability of every kind of outdoor space. The study is based on the hypothesis that the comfort conditions in each square comes as a result of the interaction of all the microclimatic parameters together. Especially for Crete it is assumed that air temperature and solar radiation are the most critical factors for achieving comfort and humidity and wind speed affect the comfort vote only when temperature conditions are not natural. The share of people who feel comfortable during the interview in Crete is about 67% annually. It is worth noticing that all squares in

6. REFERENCES [1] I.Eliasson, I. Knez, U. Westerberg, S.Thorsson, Fredrik Lindberg (2007)‖Climate and behaviour in a Nordic city‖ Landsc. and Urb. Plan.: 82 72–84 [2] M.Alcoforado, Henrique Andrade, António Lopes, João Vasconcelos(2009)‖Application of climatic guidelines to urban planning. The example of Lisbon (Portugal)‖ Landsc.&Urb.Plan.90,56–65 [3] A.Ishii, S.Iwamoto, M.Amashita, T.Atayama and Y.Shiotsuki (1993)‖An Experimental Study On The Effect Of Humidity On Thermal Sensations Of People In Summer‖ J.Therm. Biol. Vol. 18, No. 5/6 387-391 [4] R.J.De Dear, ME.Fountain(1994)‖Field exp. on occupant comfort and office thermal environments in a hot-humid climate, ASHRAE Transactions 100(2): 457-474.

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

[5] T.P.Lin.(2009)‖Thermal perception, adaptation and attendance in a public square in hot and humid regions‖ Build. & Env. 44(10): 2017-2026. [6] A.Matzarakis & H.Mayer. (2000) ―Atmospheric Conditions And Human Thermal Comfort In Urban Areas‖11th Seminar on Environmental Protection Environment and Health. 20.-23, Thessaloniki, Greece, 155-166 [7] J.M.Hamilton M.A.(Hons) MCD.(2005)‖Tourism, Climate Change and the Coastal Zone‖ Thesis Department Wirtschaftswissenschaften der Universität Hamburg [8] A.Matzarakis.(2000) ―Assessing climate for tourism purposes: Existing methods and tools for the thermal complex‖ Meteorolog. Institute, University of Freiburg [9] VDI. (1998) ―Methods for the human biometeorological evaluation of climate and air quality for the urban and regional planning‖ Part I: Climate. VDI guideline 3787. Part 2. Beuth: Berlin [10] Α.Αravadinos, T.Vlastos, D.Emmanouil, D.Marinosς ,Kouris, Κ.Μemos, G.Siskos, Κ.Sbonias, T.Τsoutsos (1999) Introduction to the natural and urban environment volume B1" . Open Greek University, Patra: pp 115-130 [11] A.Stamou, I.Katsiris, A.Schaelin (2008) ―Evaluation of thermal comfort in Galatsi Arena of the Olympics ―Athens 2004‖ using a CFD model‖ Applied Thermal Eng., Volume 28, 1206-1215 [12] W.Kuttler.(2002)‖Local cold air and its significance for the urban climate‖, University of Essen, Essen, Germany [13] M.Nikolopoulou, S.Lykoudis (2007): "Use of outdoor spaces and microclimate in a Mediterranean urban area", Build.& Env.42 3691 [14] T.P.Lin, A.Matzarakis, R.Hwang (2010): "Shading effect on long-term outdoor thermal comfort". Building and Environment 45 213–221 [15] B.Givoni and M.Noguchi (2004) Outdoor Comfort Responses of Japanese Persons, Plea 2004 The 21th Conference on Passive and Low Energy Architecture. Eindhoven, The Netherlands [16] M.A.Antar,H.Baig (2009)‖Conjugate conductionnatural convection heat transfer in a hollow building block‖ Applied Thermal Engineering, Volume 29, Is. 17-18, P. 3716-3720 [17] A.PGagge, A.P. Fobelets, Berglund, P.E. (1986): ―A standard predictive index of human response to the thermal environment‖ ASHRAE Trans., 92, 709-731 [18] K. Blazejczyk. (1994) ―New climatological-and physiological model of the human heat balance outdoor (MENEX) and its applications in bioclimatological studies in different scales‖ Zeszyty IgiPZ PAN, 28, 27-58 [19] T.Horikoshi, T.Tsuchikawa, Y.Kurazumi, N. Matsubara (1995) ―Mathematical expression of combined and separate effect of air temperature, humidity, air velocity and thermal radiation on thermal comfort‖ Archives of Complex Environmental Studies, 7, 9-12 [20] P.O.Fanger. (1970),‖Thermal Comfort, Analysis and Application in Environment Engineering‖ Danish Technical Press, Copenhagen

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[21] S.Thorsson, M.Lindqvist, S.Lindqvist (2004) ―Thermal bioclimatic conditions and patterns of behaviour in an urban park in Goteborg, Sweden‖ Int. Journal of Biometeorology 48(3): 149-156 [22] G.R.McGregor, M.T.Markou, A.Bartzokas, B.D. Katsoulis (2002) ‖An evaluation of the nature and timing of summer human thermal discomfort in Athens, Greece‖ Climate research.Vol. 20: 83–94 [23] M.Tsitoura.(2009)―Comfort conditions in urban open spaces in Crete― Thesis,Dep.Env.Eng., TUC, Palenc conference 2010 [24] ISO 7726 (1985)‖Thermal environments— instruments and methods for measuring physical quantities‖ Geneva [25] ΑSHRAE Standard (2004) ―Thermal Environmental Conditions for Human Occupancy‖ ANSI/ASHRAE 55 [26] A.P.Gagge, AP.Fobelets, LG.Berglund (1986)‖A standard predictive index of human response to the thermal environment‖ ASHRAE Transactions 92: 709-731 [27] J.Spagnolo, RJ.de Dear (2003)‖A field study of thermal comfort in outdoor and semi-outdoor environments in subtropical Sydney Australia‖ Building and Environment 38(5):721-738. [28] H.Andrade, M-J.Alcoforado (2007) ―Microclimatic variation of thermal comfort in a district of Lisbon (Telheiras) at night‖ Theoretical and Applied Climatology 92(3-4): 225-237. [29] A.Matzarakis, F.Rutz, H.Mayer(2007)‖ Modeling radiation fluxes in simple and complex environments—application of the RayMan model‖ Int J Biometeorol 51:323–334 [30] F.Ali-Toudert, H.Mayer, (2007). ―Effects of asymmetry, galleries, overhanging facades and vegetation on thermal comfort in urban street canyons‖ Solar Energy, 81, 742 – 754. [31] R.Emmanuel, H.Rosenlund, E.Johansson, (2007)‖Urban shading – a design option for the tropics? A study in Colombo, Sri Lanka‖ Int. Journal of Climatology, 27, 1995 – 2004 [32] M.Fahmy, S.Sharples, (2009)‖ On the development of an urban passive thermal comfort system in Cairo, Egypt‖ Building and Env. [33] J.Spangenberg, P.Shinzato, E.Johansson, D.Duarte (2008)‖ Simulation of the Influence of Vegetation on Microclimate and Thermal Comfort In the City of São Paulo‖ Rev. SBAU, Piracicaba, v.3, n.2, p. 1 – 19 [34] C.Yu, W.N.Hien, (2006)‖Thermal Benefits of City Parks‖ Energy and Buildings 38, pp.105 –120. [35] 2009 Y.Wang, E. Ng (2010)‖Parametric study on microclimate effects of different greening strategies in high density city‖ Conf.Palenc 2010 [36] M.Bruse, (2009) ―ENVI-met v. 3.1 Beta‖ Available at:

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Urban Heat Island Study on Building Morphology related with Micro-climate Condition and Energy Consumption within Singapore Commercial Area Nyuk Hien W ONG1, Steve KARDINAL JUSUF1, Marcel IGNATIUS1 1

Department of Building, National University of Singapore, Singapore

ABSTRACT: Urbanization has been a majority in cities. In 2008, for the first time in human history, more than half of human population live in cities and towns. By 2030, it is predicted the urban population could reach 5 billion, with urban growth concentrated in Africa and Asia. Singapore, widely known as the ‘red dot’ within South East Asia region, will be highly affected with the current urbanization issue. Singapore has become one of the world leading financial centres, where the country is also a highly cosmopolitan world city, with a key role in international trade and finance. On the other hand, the economic growth also attracts investors and foreign workers. The population increase within a small island has pushed the government to do land reclamation and build high rise buildings. The vertical growth in building construction without proper planning means only one thing; it will intensify the urban heat island (UHI) phenomenon. This paper will look into the different urban settings within Singapore commercial district, to see how the building configuration affects the micro-climate condition within urban area. By using Geographic Information System (GIS), The Screening Tool for Estate Environment Evaluation (STEVE) and coupled with TAS, a baseline condition of the urban condition can be developed. Consequently, further study will take a look how the result will affect the energy consumption by using a hypothetical building placed in the study area under different scenarios. In the end, the study aims to provide informative analysis of current and future city planning, for designers, urban planners, and researchers. Keywords: urban heat island, prediction tool, urban morphology, energy consumption

1. INTRODUCTION Related with UHI study, Givoni [1] explored the climatic characteristics relevant to urban and building design in hot humid and in hot-dry tropical regions, respectively. Location of towns in a region, density of the built-up area and building's configurations, orientation and width of streets, are the urban design elements which affect and can modify the urban microclimate. Urban density is one among other major UHI factors which determines not just urban ventilation conditions, but as well as the urban temperature. A preliminary study regarding this urban temperature which was done within different commercial area [2] in Singapore, shows that with some urban configurations, an urban area with high density of buildings can experience strong heat island effect, From the case studies, they strongly implicate that density of the built-up areas and the ratio of buildings heights to the distances between them has strong effect on the UHI magnitude. Consequently, UHI effect has direct consequence toward energy consumption. Santamouris [3] in his study regarding climatic measurement in Athens, Greece, found that where the mean heat island o intensity exceeds 10 C may double the cooling load of urban buildings, and in higher set point temperatures, the peak electricity load for cooling purposes became tripled. This paper aims to study on how UHI consequences can be mitigated by greenery, and how it will also have an effect on energy consumption. By using GIS, greenery with various Green Plot Ratio (GnPR) values will be simulated in

several urban setting scenarios under different parameters. GnPR is a planning instrument for ecological sustainability in cities [4]. The GnPR is based on a common biological parameter called the leaf area index (LAI), which is defined as the single-side leaf area per unit ground area. The GnPR is the average LAI of the greenery on site and is presented as a ratio that is similar to the building plot ratio (BPR) currently in use in many cities to control maximum allowable built-up floor area in a building development.

Figure 1: Allocated green plot ratio (GnPR) values based on ground cover (the values are rounded from data summarised by Scurlock et al [5]

2. HYPOTHESIS Hypothetically, the plantation of greenery on the site will eventually decrease temperature both in the afternoon and evening. Therefore, it will affect the building cooling load, which will result in energy consumption reduction.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Avg Bldg Height (m)

Sky View Factor

Wall Area (sq m)

AREA #1

Road Area (%)

Case studies areas from the preliminary study were chosen to be the sites for simulation purpose. To explore this aspect, the study will use a typical office building, which will be put under different temperature profiles which have been generated from previous study on greenery. The temperature profiles generated are based on the urban climate map which is made by coupling GIS and STEVE, a temperature predictor [6].

Table 1: Matrix of different urban settings within the study case area, with various urban parameters, where each of these will be placed a hypothetical office building.

Bldg Ftprint (%)

3. METHODOLOGY

1

0

61

0

0.8

0

2

52

0

12

0.4

8099

3

18

70

12

0.6

2957

4

50

37

24

0.2

12400

5

59

14

8

0.3

4927

6

43

26

45

0.1

21016

7

51

47

79

0.2

36765

8

57

29

105

0.2

43155

Buffer Area (50 m radius)

Open Town Centre study case

AREA #2 Mixed-density Fringe study case

AREA #3 High Density Commercial District study case

Figure 2: three different case study areas, where each has several placement points for the hypothetical office building.

For this purpose, TAS software is chosen as a suitable tool in order to run simulation in different weather profile, because it has been extensively used for previous energy study regarding façade performance [7]. By using TAS to calculate the cooling load, a comparative study between different urban setting scenarios can be done to see how building configurations coupled with greenery can actually mitigate the UHI effect.

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Figure 3: the hypothetical office buidling layout, which is used for cooling load calculation in TAS using temperature profiles from different zones.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The placement points will be in 50 meter radius buffer area which includes all the urban physical parameter, with the following grouping: 1) Buffer zone 1-2, are from AREA #1 2) Buffer zone 3-5, are from AREA #2 3) Buffer zone 6-8, are from AREA #3 Afterwards, 2 different approaches of implementing greenery will be put into each case study with the consideration of GnPR values. : 1) ‘Value Target’ approach; by inputting GnPR values, with the assumption that each area will be planted greenery elements to achieve the certain GnPR values. The following area the GnpR ‘value’ targets:  Scenario 1A: GnPR value target=1  Scenario 1B: GnPR value target=2  Scenario 1C: GnPR value target=3

  

Scenario 2A: all open spaces (apart from roads) are grass planted surface (turf, Leaf Area Index or LAI=1) Scenario 2B: Intermediate Canopy trees planted (crown size 3m, LAI=3) Scenario 2C: Dense Canopy trees planted (crown size 6m, LAI=4)

Table 2: The greenery implementation from the ‘design’ approach, by strategically put the road side trees. Each tree will be positioned at 6m distance between them. Buffer 1

Buffer 2

Figure 4. For scenario 2B, ‘Intermediate Canopy’ tree type is used, such as A, B and C. While tree D, E, and F are some examples of ‘Dense Canopy’ type; which are used for scenario 2C.Source: Leaf Area Indexof Tropical Plants [8].

2)

Buffer 3

Buffer 4

Buffer 5

Buffer 6

Buffer 7

Buffer 8

‘Design Target’ approach, by strategically putting grass and trees into the sites, where each tree will be assigned 2 different types of trees. The following are the scenarios for ‘design target’ simulation:

Thus, a temperature profile for each area can be generated, where it will be used as a weather data input for TAS simulation in order to calculate the cooling load of the hypothetical building. All the scenarios from both period will be compared with the condition where all the surface is paved. From TAS itself, the simulation was run two times, for both afternoon (9AM-6PM) and evening period (6PM-6AM), with assumption that the internal condition for both periods is the same. The simulated office building uses mechanical ventilation (air conditioning) for both afternoon and night load calculations. These two different calculations are meant to see how the building configurations and greenery placement could affect both temperatures during the afternoon and the heat island phenomenon after sunset in tropical climate within the urban area.

4. SIMULATION RESULT 4.1. GnPR ‘Value Target’ Simulation From this simulation study, it can be seen that a modification of surface with greenery can eventually boost the cooling load reduction. All the case studies show the same effect. In the first simulation for the afternoon period from 9am-6pm (see Figure 4 and Table 3), it illustrates that even with GnPR value of 1, it can reduce cooling load up until 1.31% (zone 6). Based on the baseline condition (paved), zone 3 has the highest cooling load number, because it has the biggest road percentage, and lesser building area which results in lesser overshadowing effect.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Therefore, the surface has direct impact of the solar radiation during the day. Meanwhile, zone 5 has the lowest cooling load, because the area has an adequate open space, lesser pavement, and high buildings to provide shadowing onto the pedestrian level. In general, greenery with the minimum GnPR of 1 can reduce afternoon cooling load averagely by 0.80%, and with the increase of GnPR value by another 1 and 2, can furthermore decrease the cooling load by 0.14% and 0.26% respectively.

for zone 2 and zone 6, they have been benefited from the GnPR modification, where they have the most cooling load percentage reduction (more than 1%).

Figure 5: Cooling load (in kilowatts), for evening period with different GnPR values implementation. Table 4: Cooling load reduction (%) on evening period (6pm-6am) compared with the ‘pavement’ surface condition.

Figure 4: Cooling load (in kilowatts), for afternoon period with different GnPR values implementation. Table 3: Cooling load reduction (%) on afternoon period (9am-6pm) compared with the ‘pavement’ surface condition.

Zone 1 2 3 4 5 6 7 8

GnPR=1 0.26 0.90 0.85 0.86 0.89 1.31 0.62 0.71

GnPR=2 0.38 1.08 0.98 0.98 1.01 1.44 0.75 0.93

GnPR=3 0.50 1.21 1.10 1.10 1.14 1.56 0.87 1.05

The role of greenery in mitigating heat island effect during the night time, in term of energy consumption, shows a similar trend line (see Figure 5 and Table 4). It has been studied that evening time is urban heat island critical period within the urban environment, since this is the time when all the heat absorbed during the day (through hard pavement and building walls) is being emitted back to the environment, causing higher temperature and ended up increasing the cooling load. Zone 3 as the one with largest pavement area, has the most severe heat island impact. While zone 6,7, and 8 (from area #3, high density CBD), have high level of cooling load, given that this area comprises high-rise buildings and dense configurations, which means more wall area. Zone 5, which has low pavement percentage and wall area, appears to have lesser heat island impact. Related to the greenery implementation, GnPR of 1 can reduce evening cooling load averagely by 0.84. Moreover, the more cooling load reduction is achievable by increasing GnPR value by 1 and 2. The simulation shows that it can subsequently decrease the cooling load by 0.18% and 0.34%. As

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Zone 1 2 3 4 5 6 7 8

GnPR=1 0.47 1.24 0.83 0.97 0.84 1.25 0.65 0.50

GnPR=2 0.63 1.40 0.99 1.13 1.00 1.42 0.81 0.80

GnPR=3 0.79 1.57 1.15 1.29 1.16 1.58 0.97 0.96

4.2. GnPR ‘Value Target’ Simulation For the second run of simulation, 3 types of greenery are planted differently. For scenario 2B and 2C, intermediate and dense canopy tree types are used, where its crown size and height dimension will reduce the sky view factor. Therefore, the modification of GnPR is followed by the sky view factor reduction consequently. Since the GnPR modification is based on the design approach, its value depends on the number of trees and the open space area for grass plantation. From the afternoon period chart (see Figure 6 and Table 5), the trend is similar with the previous result, although the significant difference is noticeable at the gap between scenario 2B and 2C. It turns out that the GnPR increase followed by the sky view factor reduction results in further cooling load decrease. Averagely, the average reduction percentage from scenario 2B to 2C is about 0.36%, where the biggest drop happens at zone 2 (this buffer are does not have any road/pavement, means the open space is wholly covered with grass). Zone 1 has the least reduction, since it comprises no buildings, and a large area of pavements.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 6: Cooling load reduction (%) based on ‘design target’ strategy during evening period (6pm-6am) compared with the ‘pavement’ surface condition.(Legend : C=crown size, in meter, LAI=leaf area index)

Zone 1 2 3 4 5 6 7 8 Figure 6: Cooling load (in kilowatts), for afternoon period by putting grass and road side trees. (Legend : C=tree crown size) Table 5: Cooling load reduction (%) based on ‘design target’ strategy during afternoon period (9am-6pm) compared with the ‘pavement’ surface condition.(Legend : C=crown size, in meter, LAI=leaf area index)

Zone 1 2 3 4 5 6 7 8

Grass LAI=1 0.18 0.90 0.75 0.75 0.80 1.23 0.51 0.71

+Tree C=3,LAI=3 0.45 1.06 0.94 0.87 0.92 1.27 0.60 1.04

+Tree C=6,LAI=4 0.65 1.66 1.26 1.29 1.35 1.54 1.01 1.25

Therefore, no over-shadowing from buildings results in more direct solar radiation hitting the ground to be absorbed by hard surface. In some areas, the lack of open spaces (such as zone 7 and 8), resulting in lesser cooling load reduction. From this result, it is understandable that the tree acts as canopy to minimize the solar heat gain from the sun, as it is also reducing the sky view factor value.

Figure 7: Cooling load (in kilowatts), for evening period by putting grass and road side trees. (Legend : C=tree crown size)

Grass LAI=1 0.37 1.16 0.68 0.83 0.71 1.14 0.49 0.50

+Tree C=3,LAI=3 0.63 1.40 0.99 1.13 1.00 1.42 0.81 0.80

+Tree C=6,LAI=4 0.79 1.57 1.15 1.29 1.16 1.58 0.97 0.96

Meanwhile, for the night period (see Figure 7 and Table 6), the significant gap between scenarios can be seen clearly between 2A and 2B, with cooling load reduction percentage difference about 0.29% (the average additional GnPR value from 2A to 2B is 0.28). On the other hand, the reduction from 2B to 2C is about 0.16% more. But overall, the trees (both intermedieate and dense canopy type) plantation gives averagely 1% reduction of the total cooling load for evening period.

5. CONCLUSIONS This paper shows not just how greenery has positive impact towards both urban temperature and reducing energy consumption, but also how to implement 2 different approaches of using GnPR into some urban setting case studies. The ‘Value Target’ strategy is the theoritical approach by using STEVE tool calculation to quickly determine how far the GnPR can reduce the temperature in urban areas. The first simulation already shows the increase of GnPR values and replacing the surface materials into green helps mitigating heat island effect, especially during the evening period. Meanwhile the ‘Design Target’ strategy, shows that by strategically planting the trees in logical manner (in this case by a simple arrangement of road side trees), with a certain type of trees results in even more better performance of energy consumption. This is a simple example on how the designers and urban planners are required to be more ‘active’ in planning and modifying the greenery implementation within a city. Planting greenery either by a simple turfing or trees planting not just provide urban canopy for the pedestrians during the afternoon, but also reducing the heat emmitance during the night, since the trees has reduced the amount of heat absorption on the pavement and road surfaces. Therefore, this will benefit the building performance, especially in the dense area. In the end, urban parameters such as openess, building heights, and road surface area affect both outdoor temperature and building cooling load. Greenery is one of the best possible strategy to reducing the energy consumption and creating a better thermal condition within urban spaces.

6. ACKNOWLEDGEMENTS This paper could not have been written without Prof. Wong Nyuk Hien who not only served as my supervisor but also encouraged and challenged me

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

throughout my academic program. He and my other colleagues, Dr. Steve Kardinal Jusuf, Nedyomukti Imam Syafii, and Terrence Tan, guided me through the process, never accepting less than my best efforts. I thank them all.

7. REFERENCES [1] B. Givoni. Atmospheric Environment. 26B (1992), 406. [2] N.H. Wong, S.K. Jusuf et al. 3rd International Conference Palenc 2010, Rhode Island – Greece (2010), Conference Paper. [3] M. Santamouris. The Canyon Effect. London, James & James Science (2001). [4] O.B. Lay. Landscape and Urban Planning. 63 (2003), 197-211. [5] J.M.O. Scurlock, Asner et al. Global Leaf Area Index Data from Field Measurements, 19322000. Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, University. http://www.daac.ornl.gov. nd [6] S.K. Jusuf and N.H. Wong. 2 International Conference on Countermeasures to Urban Heat Islands. Berkeley, United States (2009). [7] N.H Wong, W. Liping et al. Energy and Buildings 37 (2005), 563. [8] P.Y. Tan and A. Sia. Leaf Area Index of Tropical Plants. National Parks Board, Singapore (2009).

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The influence of occupation modes on building heating loads: the case of a detached house located in a suburban area Tatiana DE MEESTER1, Anne-Françoise MARIQUE2, Sigrid REITER2 1

Architecture et climat, Université catholique de Louvain, Louvain-La-Neuve, Belgium Local Environment: Management & Analysis (LEMA), University of Liège, Liège, Belgium

2

ABSTRACT: Occupants’ behaviour is known to have a great influence on energetic demand, management and consumptions of a building. However, parameters related to inhabitants’ lifestyle are often neglected in energetic studies and researches that often focus on insulation, ventilation or climate. In this context, the aim of the paper is to investigate the influence of three parameters related to human behaviour (the family size and the modes of occupations, the management of the heating system and the management of the heated area) on the housing heating loads of a standard dwelling. The case study chosen for this analysis is a detached house located in a suburban area. Five levels of insulation are tested (no insulation, an intermediate level corresponding to 3 cm of insulation, the current standard for new buildings in the Walloon region of Belgium, the low energy standard and the passive house standard) in order to highlight the impact and the interactions between occupation modes and insulation levels. The relevance of the adaptation of the living area of the house according to the evolution of the family size is finally discussed. Keywords: thermal simulation, energy consumptions, human behaviour, comfort, building performances 1.

INTRODUCTION

The use of mathematical models and simulation tools is often presented as the most credible approach to model the comportment of a building and predict the heating consumptions, in a global vision of sustainability. This approach allows to take into account a large number of parameters which are known to act upon energetic behaviour, management and consumptions of a building and to carry out parametric variations in order to test the impact of different strategies. If the level of insulation, the ventilation or the climate are often discussed in the literature, especially as far as retrofit is concerned, the influence of the composition of the household, its evolution through the whole life cycle of a dwelling or the behaviour of the occupants, which evolve over time while the house remains a fixed and unchanged size, are more rarely debated. However, these parameters have a huge impact on the energetic invoice of a household. Building operations and maintenance, occupant’s activities and indoor environmental quality, all related to human behaviour, are indeed known to have an influence as great as or even greater than climate, building envelop and energy systems [1]. In the actual context of growing interests in sustainable development and increasing energy prices, more and more households pay attention to their energetic consumptions, especially as far as heating consumptions are concerned [2] while a large part of the population, and namely elderly owners, stay reluctant to undertake heavy renovation works. The age of the occupants seems namely to have a huge impact on heating loads, and particularly on the occupancy rate and the comfort temperature [3]. Moreover, researches have shown

that in general, technical improvements were preferred over behavioural measures and especially shift in consumption. Further, home energy-saving measures seemed to be more acceptable than transport energy-saving measures [4]. The behaviour and preferences of inhabitants and the solutions adopted by the households to reduce their consumptions can thus vary in a wide proportion and cannot be apprehended by one only standard type of household in simulations, as it is generally the case. In this context, the paper aims at comparing the variations of three parameters related to human behaviours and occupation modes: the family size and the modes of occupations, the management of the heating system (thermostat) and the management of the heated area (the inhabitants occupy the ground floor and the first floor or just the ground floor). These three parameters are then used and combined in order to determine the evolution of the occupancy of the house during its life cycle. The chosen case study for this analysis is a detached house located in a suburban area because this type of house represents a large part of the building stock and of the total energy consumptions related to housing in the Walloon region of Belgium, where urban sprawl is particularly familiar [5, 6]. The methodology, simulation tools and main assumptions used in this research are summarized in section 2. Then, the impact of the three studied parameters on the evolution of heating loads and internal conditions are presented and finally discussed for five significant levels of insulation.

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2. METHODOLOGY AND ASSUMPTIONS 2.1. The TAS thermal simulation software TAS is a software package for the thermal analysis of buildings. It includes a 3D modeller, a thermal/energy analysis module, a systems/controls simulator and a 2D CFD package. CAD links are also provided into the 3D modeller as well as report generation facilities. It is a complete solution for the thermal simulation of a building, and a powerful design tool in the optimisation of a building’s environmental, energy and comfort performance. [7]

passive house. The natural ventilation (NV) corresponds to the opening of the windows from 5 pm till 6 pm (30 % of the surface of the window opened). The mixed-mode ventilation (with mechanical exhaust (ME)) and the mechanical ventilation (MV) work when the house is occupied. The ventilation has three speeds. The third and the most substantial one corresponds to the requirements of the Belgian ventilation standard [9]. The first speed, the most applied in practice, is worth 1/3 of the third one and is used in our simulations.

2.2. The climate The climate of the northern part of Europe is a temperate climate. The Brussels’ meteorological data are used. Data comprise the hourly data of temperature, humidity, global solar radiation, diffuse solar radiation, cloud cover, dry bulb temperature, wind speed and wind direction. In the analysis of the heating consumptions, a whole typical year is used [8]. The maximum and minimum temperatures, for the considered year are 34.9 °C and -9,1°C. 2.3. The studied building The studied building is a detached house with a south-east oriented facade. It is a two-storeyed house, located in a suburban area. Figure 1 shows the plans of the 2 floors of the building. The ground floor is composed of a living room, a kitchen, an office, a hall and a cloakroom. The first floor comprises 4 attic bedrooms and an attic bathroom. The windows are located on the 2 gables. One bedroom has a roof window. The house also includes a cellar and an attic. The house has a surface area of 182 m². 2.4. The thermal characteristics The analysis presented in this paper take into account 5 levels of insulation of the house: a level without insulation (NI) neither in the walls nor in the roof and the slab [9, 10], a level with 3 cm of insulation in the walls, roof and slab (3cm) [9, 10], the current standard (CS) for new buildings in Belgium [9, 10, 11, 12], a low energy level (LE) [9, 10, 13] and the passive house standard (PHS) [9, 10, 12, 14]. The main thermal characteristics of walls and windows are summarized in the Table 1. Double-glazed windows are used in the four first cases and replaced by triple-glazed windows in the

Figure 1: Plans of the ground floor and the attic floor of the studied house

2.5. The internal gains The more the building is efficient, the more internal conditions have an influence on the heating consumptions of the building. The modelling of internal gains must be representative of the reality. Thanks to the multizone modelling adopted in the analysis, internal gains can be adjusted in each room, according to the moment of the day and the occupation mode. The following heat emissions are used in the simulations [9, 13] : - Occupation: 80W per person (the number of person varies from 0 to 5 according to the occupation mode) - Fridge and deep freeze: 0.85 kWh/day - Washing-up: 0.3*1.1 kWh/use (65 uses/(year.person)) - Appliances: 50kWh/(year.person) - Television : 150W (1, 2 or 3hours/day) - Computer: 70W (0, 1, 2 or 10hours/day) - Cooking: 912W (0.5, 1 or 1.5hours/day) - Lighting: 6W/m² - Shower: 1486W/shower (0, 24 or 48 minutes/day)

Table 1: Main thermal properties of the 5 studied levels of insulation.

Roof (W/m²K)

External walls (W/m²K)

Ground floor (W/m²K)

Windows (W/m²K)

Airtightness (vol/h)

NI 3cm

3.586 0.972

1.757 0.758

1.874 0.880

1.22 1.22

CS

0.3

0.4

0.4

1.22

LE

0.265

0.326

0.395

1.22

0.6 0.6 0.39 (7.8h-1 under 50Pa) 0.1 (2h-1 under 50Pa)

PHS

0.129

0.147

0.199

0.774

Levels of insulation

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0.03 (0.6h-1 under 50Pa)

NV NV

Annual heating requirement (exigency) -

NV

-

ME

≤ 60 kWh/(m² a)

Ventilation

MV with heat recovery

≤ 15 kWh/(m² a)

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Total internal gains used in each thermal simulation depend on the chosen occupation mode and thus on combinations of the treated parameters. The reference value comes from a monitoring and is worth 2.57 W/m² [15]. 2.6. The parametric variations The study presented in this paper aims at comparing the influence of three parameters related to human behaviour and occupation mode on the heating loads. The studied parameters and their variations are presented below. The first parameter deals with the family size and the corresponding occupation mode. Two types of family composition are considered and allow to target and to characterize the four following occupation modes. - Occupation mode 1 (OM1): an active couple works outside the house during the day while their three children go to school. - Occupation mode 2 (OM2): a self-employed or unemployed couple works/stays at home during the day while their three children go to school. - Occupation mode 3 (OM3): an active couple without children works/stays outside during the day. Five cases are discussed. - Occupation mode 4 (OM4): a retired couple, not very active, spends a lot of time at home. Two cases are discussed. The second parameter deals with the management of the heating system. This modelling is based on three types of management of the thermostat, that depend on the occupation mode. The three studied cases are : - T1: 20 °C in the occupied rooms with a drop to 16 °C at night and during the day. The heating season begins the first of October and ends the first of May - T2: 20 °C in the occupied rooms with a drop to 16 °C at night. The heating season begin the first of October and ends the first of May. - T3: 21°C in the occupied rooms, all over the year , during day and night. The last parameter is the management of the heated area. The size of a family and its activities evolve over time while the house has a fixed and unchanged size but sometimes, people remove in a part of the house which became too big for them (after the departure of children for example, facing the difficulty of climbing stairs,...). In the simulations, the house is occupied either completely (ground floor and the first floor (GF)) or only partially (just the ground floor (G)). In this case, we consider that the office is transformed into a bedroom. 2.7. The studied cases Several cases can be arised from the combination of the parameters presented in the previous section. The nine studied cases are summarized in Table 2 (OM is the occupation mode, T1, T2 and T3 are the temperature settings, a cross in the GF column means that both the ground floor and the first floor are occupied (totally or partially) while a cross in the G column means that only the ground floor is occupied).

Table 2: The 9 case studied in the simulations

Case 1.1 Case 2.2 Case 3.3 Case 3.4 Case 3.5 Case 3.6 Case 3.7 Case 4.8 Case 4.9

OM

GF

1 2 3 3 3 3 3 4 4

x x x x

G

T1

T2

T3

x x x x

x x

x x x x

x x x x

3. RESULTS The results are presented in 4 parts: 1. the analysis of the 2 cases representing a family with children (case 1.1 and case 2.2), 2. the analysis of the 5 cases representing an active couple without children (cases 3.3 to 3.7), 3. the analysis of the 2 cases representing a retired couple (case 4.8 and case 4.9) and 4. the analysis of the 3 extreme cases representing 3 of the 4 modes (the cases 1.1, 3.4 and 4.9). Table 3 presents the heating loads of the 9 simulated cases for the 5 levels of insulation. In the first part of the table (part A), the total heating loads calculated for the house are divided by the total surface area of the house (182m²) in each case because if the occupied and heated area changes, the position of the insulation stays the same in each case. In the second part (part B), the total heating loads calculated are divided by the occupied and heated area (182m² if the house is totally occupied by a family (the cases 1.1 and 1.2), 138m² if the ground floor and the first floor are partially occupied by a couple (the cases 3.3, 3.4, 3.6 and 4.8) and 91m² if only the ground floor is occupied by a couple (the cases 3.5, 3.7 and 4.9)). 3.1. OM 1 and 2 : couple with 3 children Table 3 shows that case 1.1 is more energyefficient than case 2.2 for all the levels of insulation tested, excepted for the passive case. Proportionally, the biggest difference between these two cases is observed at this passive level: the difference in heating loads between cases 1.1. and 1.2 reaches 2.28 kWh/(m².year) (28.73%). For the other levels of insulation, the difference between the two cases is contained in a range between 0.75% and 8.28% (from 0.45 to 14.98 kWh/(m².year)). This table also reveals the importance of the level of insulation. The change from one level of insulation to another permits a huge reduction in heating loads. Moreover, for both considered cases, the greatest energy reductions are visible when the passive standard is reached. In general, the change from one level of insulation to the higher one is very interesting and has a greater impact than the benefit gained from occupation modes case 1.1 on case 2.2. 3.2. OM3 : active couple without children If heating loads are divided by the heated area (Part B of Table 3), 4 of the 5 cases relating to the

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Table 3: The heating loads of the 9 studied cases (in kWh/m²). The first part of the table (A) presents the total heating loads divided by the total surface area of the house (182m²). The second part (B) presents the heating loads divided by the occupied area (182m², 138m² or 91m² according to the corresp onding occupation mode).

Case 1.1

Case 2.2

Case 3.3

Case 3.4

Case 3.5

Case 3.6

Case 3.7

A.) kWh/m² (Heating loads are divided by the total surface area of the house (182m²)) NI 180.13 195.11 154.78 170.70 132.19 231.00 178.71 3 cm 96.46 101.30 92.94 101.35 88.25 132.15 115.16 CS 59.53 59.08 60.50 64.92 59.69 80.75 74.54 LE 28.46 31.03 30.18 36.19 31.99 44.82 39.74 PHS 7.25 5.16 11.88 13.28 12.76 15.93 15.39 B.) kWh/m² (Heating loads are divided by the occupied area (182, 138 or 91m²)) m² 182 182 138 138 91 138 91 NI 180.13 195.11 205.40 226.53 265.46 306.55 358.88 3 cm 96.46 101.30 123.34 134.50 177.22 175.37 231.25 CS 59.53 59.08 80.29 86.15 119.87 107.16 149.68 LE 28.46 31.03 40.05 48.02 64.24 59.48 79.79 PHS 7.25 5.16 15.76 17.62 25.61 21.14 30.91 third occupation mode do not meet the passive house standard. If the heating loads for cases 3.3 to 3.7 are divided by the total surface area of the house, the passive standard is respected. The values of cases 3.6 and 3.7 are indeed nearly beyond the bounds, especially since these cases are considered only with a “speed 1” ventilation rate. The low energy standard is not reached for case 3.5 and 3.7 (Table 3B) if the occupied area is considered but is reached when the total surface is used (Table 3A). The heating demands vary a lot according to the occupation mode (Table 3A). The two extreme cases are case 3.5 and case 3.6, The differences between these two cases vary from 98.81 kWh/(m2.year) for the non insulation case (42.77%) to 3.17 kWh/(m2.year) for the passive house standard (19.93%). The average of the differences is worth 30.10%. In general, the more the building is insulated, the more the difference between the cases decreases. The impact of behaviour becomes thus less huge and less marked. These two cases develop opposite behaviours. According to Table 3B, the two extreme cases are cases 3.3 and 3.7. The differences between heating loads are contained in a range between 153.18 kWh/(m2.year) for the non 2 insulated case and 15.15 kWh/(m .year) for the passive house standard. The average of the differences is worth 46.89%, which means that a couple, living in a house with 3cm of insulation, with a behaviour similar to case 3.7, can consume as much as a couple living in a non-insulated house with a more responsive and better managed behaviour. In general, if the building has a good insulation, the impact of the behaviour, compared with heated squared meters, can be proportionately as high as the impact of changing from a level of insulation to a better one. This result highlights the very low equilibrium between comfort and good energy management. If

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Case 4.8

Case 4.9

214.71 122.76 74.88 40.69 13.54

175.43 111.96 71.62 36.99 13.15

138 310.73 177.67 108.37 58.89 19.59

91 352.28 224.83 143.82 74.29 26.41

people have very different schedules, it is quite interesting to be able to switch on by remote control the heating and the ventilation which allows to trigger the revival of the heating system. Lowering the day temperature from 20 ° C to 16 ° C can make a saving of about 10%, by comparing cases 3.3 and 3.4. A very good insulation will reduce the consequences of the carelessness of people or of their no energy-efficient behaviour. But the reduction of consumptions remains and is thus easily improvable! 3.3. OM4: retired couple not very active The occupation mode related to retired couple that is not very active and stays at home during the day is less energy-efficient because the house is more often occupied which means more heat, more light, more cooking times. Moreover, thermal comfort is the basis of the notion of comfort for elderly households. This occupation mode requires a great need for heat and that is not negotiable. Note that heating loads predicted by these simulations are low compared to real consumptions generated by some elderly households’ behaviours, for example maintaining indoor air temperature at 26°C all over the year during day and night. Occupying just a part of the house (here the ground floor), is energetically more interesting. According to Table 3A, if the house is not insulated, the difference between cases 4.8 (the ground floor and the first floor are partially occupied) and 4.9 (the ground floor, only, is occupied) is worth 39.28 2 kWh/(m .year) (18.29%) but this difference is only worth 0.38 kWh/(m2.year) (2%) in the passive house. According to Table 3B, the average of the differences between these 2 cases is about 21% (contained in a range between 6.83 and 47.16 2 kWh/(m .year)). But these 2 cases do not concern the same surface area and thus the most consumers in terms of kWh/(m².year), the case 4.8, gives the

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

impression to consume less than the case 4.9. It might be interesting to bring in a density factor. Once again, the impact of the occupation mode in terms of kWh/m².year decreases if the insulation of the house is better.

load between cases 3.4 and 4.9 and case 1.1 is more marked if heating loads are divided by the occupied area, as it can be seen on Figure 3.

3.4. Comparison between 3 representative occupation modes: synthesis This section aims at comparing the heating loads results related to 3 extreme occupation modes. The 3 selected cases are case 1.1. (an active couple working outside the house during the day with three children going to school), case 3.4 (an active couple without children working outside the house during the day), and case 4.9 (a retired couple not very active, staying at home with a higher comfort temperature). The more the building is insulated, the more the occupation mode is marked. The comparison between case 1.1 and case 3.4 (Table 3A) highlights that the difference between heating loads is contained in a range between 5.24% (9.44 2 kWh/(m .year)) for a non-insulated house and 2 45.42% (6.03 kWh/(m .year)) for the passive house standard. The difference in heating loads between the two modes related to a couple without children (cases 3.4 and 4.9) are relatively low. The average of the differences is indeed worth 5.74%. Figure 2 shows that if the building is not insulated, the occupation mode related to the family with three children is the higher consumer of energy. But this occupation mode with children becomes more efficient than the two others modes if the house is insulated. That also reveals the importance of internal gains.

Figure 2: Heating loads (kWh/(m².year)) based on the 5 levels of insulation tested for cases 1.1, 3.4 and 4.9 (In this figure, heating loads are divided by the total surface area of the house (182m²)).

If we consider now the second part of Table 3 (where heating loads are divided by the occupied area), the differences between the three studied cases are more important. The average of the differences between case 1.1 and case 3.4 (range 2 from 10.38 to 46.39 kWh/(m .year)) and between case 3.4 and case 4.9 (range from 8.79 to 125.76 kWh/(m2.year)) are worth 36%. Case 1.1 remains the most interesting one for any level of insulation thanks to the largest heated area, to the numerous internal gains and to the better management of the heating system. The differences between the cases increase with the level of insulation even if the difference of heating

Figure 3: Heating loads (kWh/(m².year)) based on the 5 levels of insulation tested for cases 1.1, 3.4 and 4.9 (In this figure, heating loads are divided by the occupied area).

4. DISCUSSION This section aims at discussing the impact of these occupation modes during the life cycle of the house. Indeed, several occupation modes can follow one another during the life of a house. To assess their impact on the life expectancy of the studied house, 4 assumptions of occupation are established for a period of time of 100 years and summarized in Table 4. For example, in A1, the house is occupied during 45 years by a family with 3 children (case 1.1) then by an active couple without children (case 3.4) during 30 years and finally by a retired couple (case 4.9) during 25 years. Table 4 : Years of occupation of each occupation mode, for a life cycle of 100 years : 4 assumptions

Case 1.1

A1 45

A2 25

A3 60

A4 25

Case 3.4

30

50

25

55

Case 4.9

25

25

15

20

Total

100

100

100

100

Average heating loads calculated for the four scenarii of occupation presented in Table 4, and divided by the heated area, are summarized in Table 5. In two cases (A2 and A4), the requirements of the passive house standard are not met. The more the building is insulated, the more the difference of heating in % increases between the two cases. In the passive house standard, this difference reaches 26.18% (4.51 kWh/(m2.year)) between A2 and A3, that are the 2 extreme cases. If the size of family evolves over time, the size of the house and its occupation modes should also be adapted. This strategy would allow to reduce the heating consumptions during the whole life cycle of the building. The aim is to maximize the occupation of the house. But that can lead to significant works of adaptation (extra kitchen, independent entrances, etc.). The insulation and possibilities of thermal improvement of the building must also be taken into account in order to choose the best option.

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Table 5 : Average heating loads (in kWh/(m².year)) of a house on his life (100 years) based on the assumptions of occupation modes presented in Table 4.

NI 3 cm CS LE PHS

A1 237.09 139.96 88.59 45.78 15.15

A2 246.37 147.57 93.91 49.70 17.23

A3 217.55 125.22 78.83 40.22 12.72

A4 240.08 143.05 91.03 48.38 16.79

5. CONCLUSION Nine types of occupancy of a standard detached house located in a Belgian suburban area have been determined by combining several representative types of households, occupation modes and thermal preferences (management of the thermostat). Thanks to multi-zone thermal simulations performed with a dynamic thermal simulation software (TAS), heating loads have been calculated for these nine case studies and for four combinations of the most representative ones during the life cycle of the building (100 years). These analyses have highlighted the importance of internal gains related to the different modes of occupation, their influence on heating loads for the studied levels of insulation and the significance to take into account several types of households and occupation modes in thermal studies. These analyses have particularly highlighted that the more the building is insulated, the more the lifestyle, namely through internal gains, influence proportionally the heating loads even if, in terms of kWh, this impact decreases. These results emphasize that the number of inhabitants and their presence in the house can reduce the heating loads. However, insulation is paramount and increasing the insulation of the house always gives better results than just adapting the occupation mode. For the studied building, the model that presents the lower heating loads is the active couple working outside with three children, because, in this case, the number of inhabitants is quite adapted to the size of the house. The balance between optimal comfort and good management of the energy is very low and particularly if people have varied schedules. It is thus quite interesting to be able to switch on by remote control the heating and ventilation systems which allows to trigger the revival of the heating. Last but not least, a more responsible behaviour can easily improve the energy balance of a house. Buildings thermal improvements are also very efficient but take more time and money to be realized. To heighten public awareness of the impact of their lifestyle is thus crucial and can quickly lead to significant reductions in the total energy consumptions of a family.

6. ACKNOWLEDGEMENTS This research is funded by the Walloon Region of Belgium in the framework of the “Suburban Areas Favouring Energy efficiency”, project (SAFE). The authors express their thanks to the research team of

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Architecture et Climat, at the Université catholique de Louvain.

7. REFERENCES [1] W. Hilderson, E. Mlecnik, J. Cré, Potential of Low Energy Housing Retrofit: insights from building stock analysis, Belgian Science Policy, 2010. www.lehr.be. [2] L. Mettetal, La question énergétique dans l’habitat privé: le profil déterminant des ménages, Note rapide; n°476, IAU Ile-deFrance, juin 2009. [3] L. Mettetal, Les pratiques énergétiques des ménages du périurbain, Note rapide, n°485, IAU Ile-de-France, novembre 2009. [4] W. Poortinga, L. Steg, C. Vlek, G. Wiersma, Household preferences for energy-saving measures : A conjoint analysis, Journal of Economic Psychology 24, 49–64, 2003. [5] C. Kints, La rénovation énergétique et durable des logements wallons. Analyse du bâti existant et mise en évidence des typologies de logements prioritaires, LEHR, Architecture & Climat, UCL, septembre 2008. www.lehr.be. [6] A-F. Marique, S. Reiter, A method to assess global energy requirements of suburban areas at the neighbourhood scale. Proc. of the 7th International IAQVEC Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings, Syracuse, New York, 2010. [7] A.M., Jones, EDSL Ltd., TAS, Software package for the thermal analysis of buildings. 13/14 Cofferidge Close, Stony Stratford, Milton Keynes, Mk11 1BY, United Kingdom, 2010. [8] IWEC Weather Files (International Weather for Energy Calculations) from ASHRAE, American Society of Heating, Refrigerating and AirConditioning Engineers, Inc, Atlanta, USA, 2009. [9] W. Feist, Logiciel de conception de maison passive 2007 PHPP2007, Passivhaus Institut, Darmstadt, novembre 2007. [10] NORME NBN D50-001, Dispositifs de ventilation dans les bâtiments d'habitation, Bruxelles, NBN, 2008. [11] NORME NBN B 62-002, Performances thermiques de bâtiments. Calcul des coefficients de transmission thermique (valeurs U) des composants et éléments de bâtiments. Calcul des coefficients de transfert de chaleur par transmission (valeur HT) et par ventilation (valeur Hv), Bruxelles, NBN, 2008. [12] C. Delmotte, Réglementation sur la performance énergétique des bâtiments : du nouveau à Bruxelles et en Wallonie, Les Dossiers du CSTC, N° 4, Cahier n° 1, 2008. [13] www.ibgebim.be, May 2010. [14] www.maisonpassive.be, May 2010. [15] A. De Herde, M. Bodart, Les conclusions de Pléiade, Université catholique de Louvain, Architecture et Climat, 1994.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

A Review of Thermal Comfort Criteria for Naturally Ventilated Buildings in Hot-Humid Climate with Reference to the Adaptive Model Doris Hooi Chyee TOE1,2, Tetsu KUBOTA1 1

Graduate School for International Development and Cooperation, Hiroshima University, Hiroshima, Japan 2 Faculty of Built Environment, Universiti Teknologi Malaysia, Johor Bahru, Malaysia

ABSTRACT: This paper discusses the appropriateness of the existing thermal comfort criteria for naturally ventilated buildings in hot-humid climate, focusing especially on the adaptive comfort standard (ACS) by ASHRAE Standard 55-2004, based on literature review. The review covered studies related to general thermal comfort in hot-humid climate from the early attempts until present. The review revealed that thermal comfort was achieved in diverse environments in naturally ventilated buildings. Nevertheless, there were few research attempts to develop a comprehensive thermal index for hot-humid climate that could be applied across a wide range of thermal conditions. Thermal indices which account for the effect of evaporative heat transfer at high air movement were applied in less than 20% of the studies found in this review. Recent studies were greatly influenced by and, in turn, supported the adaptive model. However, the applicability of the current ACS, given in operative temperature, may be limited to low air movement conditions in hot-humid region. In order to be useful for both low and higher range of air velocities, a new adaptive comfort standard using SET*, or thermal indices developed to account for evaporative heat loss, may be more appropriate for naturally ventilated buildings in hothumid climate. Keywords: thermal comfort, hot-humid climate, natural ventilation, adaptive model

1. INTRODUCTION Standards for thermal comfort play a role in informing decisions related to building cooling and heating, which, in turn, have considerable implications on building energy demand [1]. Since natural ventilation is one of the important passive cooling techniques for improving thermal comfort in hot-humid climate, comprehensive thermal comfort criteria which include the evaluation of evaporative heat loss may be needed in this climatic region, especially for the naturally ventilated buildings. This is important to ensure occupants’ satisfaction with the thermal environment as well as reduce air conditioning to conserve energy. Although numerous significant thermal comfort standards have been proposed based on extensive studies, most of the criteria were developed for conditioned spaces in moderate or cold climates using controlled climate chambers [2-4]. The recent adaptive model puts forward field evidence that occupants demand different thermal comfort conditions in conditioned buildings compared to naturally ventilated buildings [5]. Subsequently, the adaptive comfort standard (ACS) was proposed in ASHRAE Standard 55-2004 [2] to specify thermal comfort criteria for naturally ventilated buildings. The adaptive model shows that acceptable indoor temperature depends on outdoor climate. Although development of the ACS included some studies in the tropics, its applicability to hot-humid climate has not been verified. This paper discusses the appropriateness of the existing thermal comfort criteria for naturally ventilated buildings in hot-humid climate, focusing

especially on the adaptive comfort standard (ACS) by ASHRAE [2], based on literature review. The review covers studies related to general thermal comfort in hot-humid climate from the early attempts until present, and the ACS.

2. REVIEW RESULTS 2.1. Early Attempts in Hot-Humid Climate Early thermal comfort studies in the tropics were conducted mainly to understand the thermal comfort requirements of occupants and examine the relationship of the physical parameters (air temperature, radiant temperature, air velocity and humidity) to thermal sensation. Among the earliest surveys performed are those by Webb [6,7] and Ellis [8] in the 1950s, followed by Wyndham [9], Rao and Ho [10] and Sharma and Ali [11,12]. All the surveys were carried out in naturally ventilated buildings under the subjects’ normal daily routine and clothing. Particular interest was given to analyze the prevailing outdoor climate, adequacy of indoor air movement, occupants’ behaviour and feeling of skin wetness. It is evident that research on thermal comfort in naturally ventilated buildings is not new in the tropical region. However, relatively few studies can be found in the literature before 1990. Some thermal indices were developed as a result of the above studies. These include the Singapore Index [7], Equatorial Comfort Index [13], Thermal Stress Index [11] and Tropical Summer Index [12]. Prior to the development of these indices, comfort temperatures were indicated using the Effective Temperature (ET) [6,8]. It should be noted that all the above early indices evaluate the effects of air movement and humidity on thermal sensation.

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However, the early tropical indices were not widely used after their establishment and not developed further to produce a more comprehensive index, as the Standard Effective Temperature (SET*) [14] was from ET. 2.2. Recent Attempts in Hot-Humid Climate Many thermal comfort studies can be seen in hothumid region in the recent two decades (1990-2010). These studies can be generally classified into climate chamber studies and field studies. Although some climate chamber studies [15-20] have been conducted in hot and humid conditions, our review found that field studies were still by far more popular than climate chamber studies in the tropics. This is probably because emerging researchers during the recent period were more attracted to the adaptive model, which calls for field studies. In particular, this period coincided with the commencement of ASHRAE RP-884 [21], the project which contributed to the development of ACS (see Section 2.3). Some of the recent field studies [22-26] in the tropics participated in ASHRAE RP-884 and were included in the meta-analysis that produced the adaptive algorithm. Each study surveyed both naturally ventilated and air-conditioned buildings for comparison purposes except for one study [23]. The trend to compare arose out of consciousness of energy use in building cooling and this group of studies signifies the beginning of such trend in hothumid climate. Numerous other field studies were carried out in naturally ventilated buildings [27-41], air-conditioned buildings [42-50] and combination of both in the same study [51-59]. The field studies in naturally ventilated buildings in a way can be seen as a continuation of the early attempts to further determine the thermal comfort requirements of occupants (see Section 2.1). They were also performed under occupants’ ordinary daily activity, clothing and environment. Nevertheless, they did not continue to utilize the tropical indices developed from those early surveys. Measurements of all physical variables were taken in the major studies, yet recent researchers were mostly found to report comfort conditions using simple indices such as air temperature, operative temperature and globe temperature. One of the reasons given was these indices provided higher correlations with the subjective assessments [27]. Another reason was to compare their results with other recent field studies and existing thermal comfort standards [34,38]. In all, studies which encountered higher air velocities reported that comfort temperatures voted by respondents also increased accordingly [27,29,36,39,49,56]. One of the studies [27] claimed that the cooling effect of air movement was observed only at air velocities greater than 0.3 m/s, and the highest recommended air velocity found in this review is 3 m/s [29]. Although absolute values of the air velocities and corresponding comfort temperatures differed among the studies, it is agreeable that poor ventilation was probably the most important reason for the discomfort of

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occupants in naturally ventilated buildings in the tropics [58]. 2.3. Adaptive Comfort Standard (ACS) The adaptive comfort standard (ACS) was formalized in a standard for the first time in ASHRAE Standard 55-2004 [2] based on meta-analysis of ASHRAE RP-884 field studies [21]. Its formulation is documented in Refs. [60,61]. The ACS determines acceptable indoor operative temperature for naturally ventilated buildings based on the mean monthly outdoor air temperature [2]. It places no limit on air velocity, humidity and clothing, which reflects its intention to encourage use of such adaptive controls. It is important to note that the choice of a suitable thermal index in the adaptive algorithm has been repeatedly given attention [21,60-62]. At present, the terms in the ACS algorithm are mean monthly outdoor air temperature and indoor operative temperature which considers only convective and radiative heat exchanges. Existing literatures inform that pragmatism was the priority in selecting the two terms, thus the simple indices prevailed over more complex ones. As reported in [61], there was a decision change from using ET* to air temperature to characterize the outdoor climate for ease of use by practitioners. On the other hand, it is acknowledged that the operative temperature ‘achieved the best correlations with thermal sensation votes’ in a majority of the database among four major indices (ET*, PMV and SET*) [60].

3. DISCUSSION 3.1. Research Trend in Hot-Humid Climate The above review distinguished thermal comfort studies in hot-humid climate into early attempts (pre1990) and recent attempts (1990-2010). The early phase concentrated on two fundamental aspects: (1) understanding thermal comfort requirements of occupants in naturally ventilated buildings; and (2) developing thermal index. Together with the recent attempts, it has been clarified that occupants require higher air velocities at higher air temperatures to expedite sweat evaporation and still feel comfortable in hot-humid climate. However, for the latter aspect, few early attempts were found resulting in limited development of tropical indices to assess the effect of evaporative heat loss. Fig. 1 shows the share of thermal comfort studies reviewed in this paper [2,6-12,15-20,22-59] which used thermal indices that include and exclude evaporative heat loss. As shown, only about 12% of the studies used the early indices, i.e. ET, Singapore Index, Equatorial Comfort Index and Tropical Summer Index. As before, these early indices include the evaluation of evaporative heat loss. Combining both early indices and SET*, Fig. 1 depicts that less than 20% of the studies found in this review applied thermal indices which account for the effect of evaporative heat transfer at high air movement. In comparison, more than 80% of the reviewed studies applied other indices, i.e. air temperature, operative temperature, globe temperature, ET* and equivalent temperature.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Early Indices 11.5%

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Figure 1: The share of thermal comfort studies which include (early indices and SET*) and exclude evaporative heat loss (other indices).

The recent attempts emerged as a continuation of the former aspect of the early phase and also out of curiosity to examine the closeness of thermal perceptions in hot-humid climate compared to major standards including ASHRAE Standards 55, PMV and ACS. On the whole, recent studies were greatly influenced by and, in turn, supported the adaptive model. Although there are increasing concern and efforts to develop thermal comfort criteria for hothumid climate, the process to standardize a set of thermal comfort criteria in this region has not taken place. Furthermore, considering that thermal comfort was achieved in diverse environments in naturally ventilated buildings, there is still a weak area in terms of development and validation works for a comprehensive thermal index that could be applied across a wide range of thermal conditions. 3.2. Appropriateness of the ACS The adaptive comfort standard (ACS) applies a simple thermal index, i.e. operative temperature, to characterize indoor comfort temperature. The simpler temperature index is sufficient and in a way very useful when indoor thermal environment is close to the standard environment, which is at low air velocity and 50% relative humidity [62]. However, the conditions may not be so in hot-humid climate especially when high air velocity is essential, and promoted by the adaptive model, to aid evaporative heat loss by sweat. This deficiency may be observed in two ways. First is the use of a thermal index which considers only convective and radiative heat exchanges, i.e. operative temperature, as explained above. Second is not specifying the acceptable (and required) range of air velocities for the corresponding comfort temperatures even though the ACS does not restrict air velocity to any limit. To be used as a standard particularly for hot-humid climate, this may bring two implications – under provision of the required air velocities to building occupants and underestimation of the potential for higher comfort temperatures under increased air velocities. To discuss the above deficiency further, comfort temperatures have been clustered in groups according to the thermal index used and corresponding mean air velocity for the comfort condition. Fig. 2 presents the comfort temperatures reported in hot-humid climate studies which provide air velocity data [6-8,10-12,19,20,22-24,27,29,33-

36,39-41,43-46,48-50,52,54,56,58] as a function of the mean monthly outdoor air temperature. They are shown separately for naturally ventilated buildings (Fig. 2a) and air-conditioned buildings (Fig. 2b). Mean monthly outdoor air temperatures were obtained from the respective papers and if not given, they were sourced from Refs. [63-65] according to the survey months and locations reported in the papers. In Fig. 2a, the ACS [2] 80% and 90% acceptability limits are indicated for evaluating the criteria for naturally ventilated buildings while in Fig. 2b, the ASHRAE [2] 0.5 clo comfort zones are shown for the same purpose for air-conditioned buildings. As illustrated in Fig. 2a, the ACS acceptability limits generally agree well with neutral temperatures reported from field studies in naturally ventilated buildings under air velocities below 0.3 m/s. This can be said of the early indices and also other indices, although there is no criterion using SET* to be compared. Nevertheless, some upper limits from the same air velocity group, particularly other indices, are 2-3°C above the ACS upper limit. Under higher air velocities, some of the neutral temperatures which used other indices exceed the ACS upper limit by about 2°C while some of the corresponding comfort limits are up to 6°C above and 1°C below the ACS acceptability limits. In comparison, both neutral temperatures and comfort limits which applied early indices are within the ACS acceptability limits while neutral SET* are near the ACS lower limit, even under air velocities of 0.3 m/s or more (Fig. 2a). Although occupants’ different expectation and acclimatization might have contributed to the diversity in comfort temperatures, the difference seen between the two air velocity groups for other indices is most likely due to the effect on evaporative heat loss of different levels of air movement. The analysis implies that the current ACS, given in operative temperature, may be applicable to naturally ventilated buildings in hot-humid climate in low air movement conditions. Even that, neutral temperatures using other indices tend to be in the upper half of the ACS comfort band (Fig. 2a). To be useful for both low and higher range of air velocities, a new adaptive comfort standard using SET*, or thermal indices developed to account for evaporative heat loss, may be needed and more appropriate for hot-humid climate. For air-conditioned buildings, Fig. 2b shows that the comfort temperatures found in this review are less spread out than those for naturally ventilated buildings even though the range of mean monthly outdoor air temperature is similar (cf. Fig. 2a). This is quite logical as the air-conditioned buildings mostly encountered relatively constant indoor environment regardless of outdoor climate. Nevertheless, some of the neutral temperatures under air velocities below 0.3 m/s using other indices still exceed above and below the ASHRAE comfort zone (ET*) by more than 1°C, and the corresponding comfort limits by more than 3°C. This could be partly due to the clothing worn with insulation lower and higher than 0.5 clo. Neutral temperatures applying SET* also fall within and above the ASHRAE comfort zone (SET*) (Fig. 2b). Under higher air velocities, most of the neutral

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temperatures, which were all reported in other indices, are above the ASHRAE comfort zone (ET*). In general, the above analysis supports the distinction between thermal comfort criteria for naturally ventilated and air-conditioned buildings as proposed by the adaptive model. Given that the variability of comfort temperatures are different for naturally ventilated and airconditioned buildings, Figs. 3 and 4 compare their frequency distributions of neutral temperature and comfort band respectively. For naturally ventilated buildings, the neutral temperatures average about 28°C with a standard deviation of 1.96°C on the whole (Fig. 3a). The corresponding comfort bands average about 6°C with a standard deviation of 2.43°C (Fig. 4a). Overall, these statistical values are higher than those of air-conditioned buildings (cf. Figs. 3b and 4b). However, it should be carefully noted that the present database is highly dominated by other indices. It can be seen that for naturally ventilated buildings, average neutral temperature in early indices and SET* combined is 3°C lower and average comfort band in early indices is almost

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3.5°C narrower than those of other indices respectively (Figs. 3a and 4a). These differences are probably due to the effects of evaporative heat loss provided by air movement that is considered in early indices and SET*, but not in other indices. On the other hand, average neutral temperature in SET* is quite close with that of other indices for airconditioned buildings (Fig. 3b). This analysis further implies the need to consider using comprehensive thermal indices to fully evaluate thermal comfort for naturally ventilated buildings in hot-humid climate.

4. CONCLUSION The above review revealed that the applicability of the current ACS, given in operative temperature, may be limited to low air movement conditions in naturally ventilated buildings in hot-humid region. In order to be useful for both low and higher range of air velocities, a new adaptive comfort standard using SET*, or thermal indices developed to account for evaporative heat loss, may be more appropriate for hot-humid climate.

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5. ACKNOWLEDGEMENTS This study was supported by grant from the Asahi Glass Foundation. Scholarship from The Hitachi Scholarship Foundation is gratefully acknowledged.

[1] G.R. Milne (1995), The energy implications of a climate-based indoor air temperature standard, in: F. Nicol, M. Humphreys, O. Sykes and S. Roaf (Eds.), Standards for Thermal Comfort, E & FN Spon, London, 182. [2] ASHRAE (2004), ASHRAE Standard 55-2004: Thermal Environmental Conditions for Human Occupancy, ASHRAE Inc., Atlanta. [3] BSI (2006), BS EN ISO 7730:2005, Ergonomics of the Thermal Environment – Analytical and Interpretation of Thermal Comfort Using Calculations of the PMV and PPD Indices and Local Thermal Comfort Criteria, BSI, London. [4] P.O. Fanger (1972), Thermal Comfort: Analysis and Applications in Environmental Engineering, McGraw-Hill Book Co., New York. [5] G.S. Brager and R.J. de Dear (1998), Energy and Buildings 27 (1), 83. [6] C.G. Webb (1952), Journal of the Institution of Heating and Ventilating Engineers 20, 189. [7] C.G. Webb (1959), British Journal of Industrial Medicine 16, 297. [8] F.P. Ellis (1953), Journal of Hygiene 51, 386. [9] C.H. Wyndham (1963), British Journal of Industrial Medicine 20, 110. [10] K.R. Rao and J.C. Ho (1978), Building and Environment 13 (3), 161. [11] M.R. Sharma and S. Ali (1979), A thermal stress index for warm, humid conditions in India, Educational Building Report 14, UNESCO Regional Office for Education in Asia and Oceania, Bangkok. [12] M.R. Sharma and S. Ali (1986), Building and Environment 21 (1), 11. [13] F.A. Chrenko (Ed.) (1974), Bedford’s Basic Principles of Ventilation and Heating, third ed., HK Lewis & Co. Ltd., London. [14] A.P. Gagge, A.P. Fobelets and L.G. Berglund (1986), ASHRAE Transactions 92 (Part 2), 709. [15] R.J. de Dear, K.G. Leow and A. Ameen (1991), ASHRAE Transactions 97 (Part 1), 874. [16] R.J. de Dear, K.G. Leow and A. Ameen (1991), ASHRAE Transactions 97 (Part 1), 880. [17] A.M. Abdul Shukur (1993), Human thermal comfort in tropical climates, Doctoral Thesis (unpublished), University College London, London, cited in: A.M. Ismail (1996), Wind-driven natural ventilation in high-rise office buildings with special reference to the hot-humid climate of Malaysia, Doctoral Thesis (unpublished), University of Wales College of Cardiff, Wales. [18] M. Zainal (1993), Proc. INDOOR AIR ’93, Vol. 6, Helsinki – Finland, 157. [19] K. Shimura, T. Horikoshi and S. Miyamoto (1996), Proc. INDOOR AIR ’96, Vol. 1, Nagoya – Japan, 281. [20] H. Kubo, N. Isoda and H. Enomoto-Koshimizu (1997), Building and Environment 32 (3), 211.

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[21] R.J. de Dear, G. Brager and D. Cooper (1997), Developing an adaptive model of thermal comfort and preference, ASHRAE RP-884 Final Report, Macquarie Research Ltd., Sydney. [22] R.J. de Dear, K.G. Leow and S.C. Foo (1991), International Journal of Biometeorology 34 (4), 259. [23] R. de Dear and M. Fountain (1994), ASHRAE Transactions 100 (Part 2), 457. [24] J.F. Busch (1995), Thermal comfort in Thai airconditioned and naturally ventilated offices, in: F. Nicol, M. Humphreys, O. Sykes and S. Roaf (Eds.), Standards for Thermal Comfort, E & FN Spon, London, 114. [25] J.F. Nicol, I.A. Raja, A. Allaudin and G.N. Jamy (1999), Energy and Buildings 30 (3), 261. [26] T.H. Karyono (2000), Building and Environment 35 (1), 77. [27] F.H. Mallick (1996), Energy and Buildings 23 (3), 161. [28] S. Abdul Rahman and K.S. Kannan (1997), Proc. Asia-Pacific Conference on the Built Environment, Petaling Jaya – Malaysia, 137. [29] J. Khedari, N. Yamtraipat, N. Pratintong and J. Hirulabh (2000), Energy and Buildings 32 (3), 245. [30] M.N. Ibrahim and M.S. Hidayat (2001), A field experiment to determine thermal comfort criteria of Malaysians in residential buildings, Siri Kertas Kerja Penyelidikan (UTM Research Manangement Centre), Universiti Teknologi Malaysia, Skudai. [31] N.H. Wong, H. Feriadi, P.Y. Lim, K.W. Tham, C. Sekhar and K.W. Cheong (2002), Building and Environment 37 (12), 1267. [32] N.H. Wong and S.S. Khoo (2003), Energy and Buildings 35 (4), 337. [33] H. Feriadi and N.H. Wong (2004), Energy and Buildings 36 (7), 614. [34] R.A. Memon, S. Chirarattananon and P. Vangtook (2008), Building and Environment 43 (7), 1185. [35] A.C. Ogbonna and D.J. Harris (2008), Applied Energy 85 (1), 1. [36] S. Wijewardane and M.T.R. Jayasinghe (2008), Renewable Energy 33 (9), 2057. [37] G. Gomez-Azpeitia, G. Bojorquez, P. Ruiz, R. Romero, J. Ochoa, M. Perez, O. Resendiz and A. Llamas (2009), Proc. PLEA2009, Quebec City – Canada, 498. [38] A. Tablada, F. De Troyer, B. Blocken, J. Carmeliet and H. Verschure (2009), Building and Environment 44 (9), 1943. [39] C. Cândido, R.J. de Dear, R. Lamberts and L. Bittencourt (2010), Building and Environment 45 (1), 222. [40] N. Djongyang and R. Tchinda (2010), Energy Conversion and Management 51 (7), 1391.

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COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

[41] M. Indraganti (2010), Building and Environment 45 (3), 519. [42] M. Zainal and C.C. Keong (1996), Proc. INDOOR AIR ’96, Vol. 2, Nagoya – Japan, 601. [43] J. Nakano, S. Tanabe and K. Kimura (2002), Energy and Buildings 34 (6), 615. [44] K.W.D. Cheong, E. Djunaedy, Y.L. Chua, K.W. Tham, S.C. Sekhar, N.H. Wong and M.B. Ullah (2003), Building and Environment 38 (1), 63. [45] K.W.H. Mui and W.T.D. Chan (2003), Building and Environment 38 (6), 837. [46] N. Yamtraipat, J. Khedari and J. Hirunlabh (2005), Solar Energy 78 (4), 504. [47] R-L. Hwang, T-P. Lin, M-J. Cheng and J-H. Chien (2007), Building and Environment 42 (8), 2980. [48] K.W. Mui and L.T. Wong (2007), Building and Environment 42 (2), 699. [49] S. Atthajariyakul and C. Lertsatittanakorn (2008), Energy Conversion and Management 49 (10), 2499. [50] R-L. Hwang, K-H. Yang, C-P. Chen and S-T. Wang (2008), Building and Environment 43 (12), 2013. [51] M. Zainal and H. Adnan (1997), Proc. AsiaPacific Conference on the Built Environment, Petaling Jaya – Malaysia, 121. [52] A.G. Kwok (1998), ASHRAE Transactions 104 (Part 1), 1031. [53] K. Jitkhajornwanich and A.C. Pitts (2002), Building and Environment 37 (11), 1193. [54] A.G. Kwok and C. Chun (2003), Solar Energy 74 (3), 245. [55] R-L. Hwang, T-P. Lin and N-J. Kuo (2006), Energy and Buildings 38 (1), 53. [56] P. Rangsiraksa (2006), Proc. PLEA2006, Geneva – Switzerland. [57] J. Han, G. Zhang, Q. Zhang, J. Zhang, J. Liu, L. Tian, C. Zheng, J. Hao, J. Lin, Y. Liu and D.J. Moschandreas (2007), Building and Environment 42 (12), 4043. [58] W. Yang and G. Zhang (2008), International Journal of Biometeorology 52 (5), 385. [59] R-L. Hwang, M-J. Cheng, T-P. Lin and M-C. Ho (2009), Building and Environment 44 (6), 1128. [60] R.J. de Dear and G.S. Brager (1998), ASHRAE Transactions 104 (Part 1), 145. [61] R.J. de Dear and G.S. Brager (2002), Energy and Buildings 34 (6), 549. [62] M.A. Humphreys, J.F. Nicol and I.A. Raja (2007), Advances in Building Energy Research 1, 55. [63] http://worldweather.wmo.int/ [64] http://ds.data.jma.go.jp/gmd/tcc/climatview/ [65] http://www.cwb.gov.tw/V6e/index.htm

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBN th xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

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Comfort temperatures and comfort range in low cost dwellings in arid climate. Luis Carlos Herrera,1 Gabriel Gómez-Azpeitia2, Pavel Ruiz3 and Adolfo Gomez4

(1) University of Ciudad Juarez- ISTHMUS Norte, Mexico; (2) University of Colima, Mexico; (3) University of Chiapas, Mexico; (4) University of Colima, Mexico.

ABSTRACT: This paper presents the results of a field study on thermal comfort of inhabitants of low cost dwellings in two cities of the northern arid region of Mexico: Chihuahua (lat: 28N, long: 106W) and Ciudad Juarez (lat: 31N, long: 106W). The field study was conducted upon the adaptive approach of thermal comfort, and according the ISO 10551 requirements. The survey was applied to 531 inhabitants of dwellings built by the Chihuahua State Housing Institute, during two periods in 2010: cold season (February) and hot season (July). Given that the climate of the region has features of “asymmetric” climates, so called by Nicol (1993), the data obtained in the field study was analyzed by the Averages for Thermal Sensation Intervals Method (ATSI) (Gomez-Azpeitia et alt, 2009). The research has as objectives to carry out an assessment of this kind of housings offered by the local government and to propose recommendations for the design of new dwellings. Keywords: thermal comfort, arid climate, adaptive approach neutral temperature.

1. INTRODUCTION The present paper presents the results of a field study made in the cities of Juarez and Chihuahua, located in the state of Chihuahua, in northern Mexico. The study was done to evaluate if the low cost housings promoted by the Chihuahua's State Housing Institute favors the inhabitants' thermal comfort, with the goal of making recommendations directed to improve the comfort levels in the designs of new dwellings.

Figure 2: Chihuahua and Juarez location.

2. CLIMATE Figure 1: Map of Mexico

The city of Chihuahua is located in latitude 28ºN, longitude 106°W and a height of 1425masl. Ciudad Juarez is in latitude 31ºN, longitude 106W and 1150masl.

The climate in Chihuahua is considered dry and extreme. The yearly average temperature fluctuates between 10.08ºC and 29.9ºC with extremes up to 41.3ºC in summer and -12.8°C in winter. The average relative humidity is 52.4% with minimums of 14.4%. The climate in Juarez is considered dry, extreme and with medium relative humidity. The yearly average temperature fluctuates between 10.03ºC and 25.8ºC with extremes up to 45.0ºC in summer and 23.0°C in winter. The average relative humidity is 46.6%, with minimums of 29.4%.

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Table 1: Vote or value appreciation of the people interviewed.

Figure 3: Monthly Average Temperatures in Chihuahua.

Figure 4: Monthly Average Temperatures in Juarez.

3. METHOD The investigation method was of the transversal type. Surveys were applied in each city in two different seasons’ denominated winter (February 2010) and summer (July 2010). A total of 531 surveys were applied during the whole research. Of these, 272 were in the winter season, 146 in Chihuahua and 126 in Juarez; 259 were made in summer season, 123 in Chihuahua and 136 in Juarez. The selection of the houses and the work area was determined together with the Chihuahua's Housing Institute. Housing states were chosen in Chihuahua and Juarez with progressive growth, 2 whose initial built surface is 23.76 m . The surveys were made inside the houses during day hours. Only people between 14 and 70 that hadn't just showered or had been cooking were surveyed. The questionnaires were designed complying with ISO 10551 [3] and other studies, including the personal suggestions of B. Givoni during an academic visit at University of Colima, Mexico in 2003. The process and instruments comply with ISO 7726 [4] so the generated data are considered Class I, as classified by Brager and de Dear [4]. Simultaneously to the survey we register inside the housings dry bulb temperature (DBT), wet bulb temperature (WBT), relative humidity (RH), black globe temperature (BGT), and unidirectional wind speed (WS) The answers of the subjects under the survey were organized according to the scale of ASHRAE [5] (table 1). 2

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Value

Vote or appreciation

1 2 3 4 5 6 7

Very cold Cold Some cold Niether heat nor cold Some heat Heat Very hot

To analyze the results and obtain the neutral temperature and the range of thermal comfort, the method called Averages for Thermal Sensation Intervals Method (ATSI) (Gomez-Azpeitia et alt, 2009) [1], for "asymmetric” climates [2] was used. This method was developed in order to avoid the bias generated when the answers to thermal sensation from volunteers on field studies tend to move towards one end of the scale, leaving the other end without answers. In such conditions, the neutral temperature (Tn) obtained through a conventional method does not represent people’s true opinions. The development of the method is based in the adaptive focus of thermal comfort, which implies the interaction of physical and biological variables (climate, metabolism, clothing) along with psychological ones (adaptation, tolerance, desirability). [2] During the survey's application, the climate data inside the house that was captured was dry bulb temperature (DBT), wet bulb temperature (WBT), black globe temperature (BGT), relative humidity (RH) and wind speed (WS). Once we collected the data, distribution ranges were established for each answer interval. To do so, the ± standard deviation (s) is added to the mean temperature (Tm) for each interval. Theoretically, this first range includes two thirds of people who expressed the same thermal sensation. The procedure is repeated by adding ± 2s to the Tm, which would theoretically include almost all people who recorded the same thermal sensation. Finally, a linear regression is applied to the standard deviations obtained, in order to determine the lines corresponding to the limits for a wide range defined by Tm ± 2s, and for a close range defined by Tm ± s. The same procedure has to be done with mean temperatures. In this way, we created a chart for each season. The intersection of each regression line with ordinate four —representing neutral thermal sensation—, determines the neutral temperature according to the ATSI method, as well as the temperatures limiting the comfort ranges (see figures 5, 6, 9 and 10).

4. RESULTS 4.1 Chihuahua In winter, a neutral temperature (Tn) of 18.70°C, was obtained with an upper limit of 21.41°C and a lower one of 16.20°C. The close range in this case

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

was of 5.22°C (-2.5°C, +2.72°C) and the wide range of 9.92°C (-4.4°C, +5.52°C) (figure 5).

Figure 5: Application of the ATSI Method on data collected in Chihuahua in winter.

Figure 7: Comparison between the Dry Bulb Temperature (DBT) and Neutral Temperatures (Tn) inside the different ranges, Chihuahua in winter.

During summer the value of Tn was 29.19°C, with an upper limit of 30.89°C and a lower one of 27.44° C. The close range was of 3.45°C (-1.75°C, +1.70°C) and the wide range of 6.89°C (-3.55°C, +3.34°C) (figure 5). In this season the upper and lower limits of the comfort range have a lesser extent in comparison with those of the winter season. The results show us that when the season is cold the lower limit is smaller than the upper and when the season is hot this condition is inverted.

DBT

Figure 8: Comparison between the Dry Bulb Temperature (DBT) and Neutral Temperatures (Tn) inside the different ranges, Chihuahua in summer.

4.2 Juarez

Figure 6: Application of the ATSI Method on data collected in Chihuahua in summer.

In winter, a Tn of 18.45°C was obtained, with an upper limit of 19.96°C and a lower one of 17.14°C. The close range in this case was of 2.82°C (-1.31°C , +1.51°C) and the wide range of 6.76°C (-2.55°C, +4.21°C) (figure 9).

The extent of the annual Tn is 10.49°C, the close range is of 14.69°C and the wide range of 18.23°C. Table 2: Ranges magnitude in K degrees, Neutral Temperature (Tn) and Comfort Limits values in C degrees. Chihuahua, Mexico. 1) Winter. (February) Close Range Wide Range Tn 5.22

Lower Upper Limit Limit 16.20 21.41 2) Summer. (June) Close Range Lower Limit 27.44

3.45

Upper Limit 30.89

Lower Limit 14.30

9.92

MRL

Upper Limit 24.22

Wide Range Lower Limit 25.64

6.69

18.70

Tn MRL

Upper Limit 32.53

29.19

Figure 9: Application of the ATSI Method on data collected in Juarez.

In summer, the Tn was 29.54°C, with an upper limit of 31.44°C and a lower limit of 27.33°C. The close range in this case was of 4.11°C (-2.21°C, +1.90°C) and the wide range of 7.19°C (-4.54°C, +2.65°C) (figure 10). The ranges have a lesser exte nt in comparison with those found for Chihuahua.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

4.3 Comparison with another method. We compared the Neutral Temperatures from the field study with results obtained through the Auliciem’s formula [6]: Tn = 17.6 + .31 (To) Where: To = Monthly Mean Outdoor Temperature

Figure 10: Application of the ATSI Method on data collected in Juarez.

The extent of the annual Tn is 11.09°C, the close range of 14.30°C and the wide range of 16.29°C. Table 3: Ranges magnitude in K degrees, Neutral Temperature (Tn) and Comfort Limits values in C degrees at Juarez. 1) Winter. (February) Tn Close Range Wide Range Lower Limit

2.82

17.14

Upper Limit

Lower Limit

19.96

15.90

6.76

MRL

Upper Limit 22.67

2) Summer. (June) Close Range Lower Limit 27.33

4.11

Upper Limit 31.44

Wide Range Lower Limit 25.0

18.45

7.19

Upper Limit 32.19

Tn MRL

29.54

DBT

Figure 11: Comparison between the Dry Bulb Temperature (DBT) and Neutral Temperatures (Tn) inside the different ranges, Juarez in winter.

Also we compared the amplitude of comfort ranges from the field study with the amplitude of ±1.75 proposed by Auliciem and Szokolay [7] We find that in Chihuahua the neutral temperature obtained from the field data in winter is 3.1 ºC lower than the neutral temperature calculated according Auliciem. In turn, the neutral temperature in summer from field data is 3.7 ºC upper than the neutral temperature calculated according Auliciem (table 4). Table 4. Tn summary of calculated and collected in Chihuahua. Chihuahua Winter Summer Concept Field Field Auliciem Auliciem Study Study Tn 18.70 21.85 29.19 25.50 Lower limit 16.20 20.10 27.44 23.75 Upper limit 21.41 23.60 30.89 27.25 Close range 5.22 3.50 3.45 3.50 All data in Celsius degree.

In Juarez the neutral temperature obtained from the field data in winter is 2.4 ºC lower than the neutral temperature calculated according Auliciem. In turn, the neutral temperature in summer from field data is 3.2 ºC upper than the neutral temperature calculated according Auliciem (table 5). Table 5. Tn summary of calculated and collected in Juarez. Juárez Winter Summer Concept Field Field Auliciem Auliciem Study Study Tn 18.45 20.80 29.54 26.36 Lower limit 17.14 18.30 27.33 24.61 Upper limit 19.96 23.30 31.44 28.11 Close range 2.82 3.50 4.11 3.50 All data in Celsius degree.

In winter 91% of the people in Chihuahua and 90% in Juarez consider from tolerable to perfectly tolerable the thermal environment inside their houses at the time of the survey. In summer it's reduced to a 73% in Chihuahua and 82% in Juarez.

4. PROPOSALS

DBT

Figure 12: Comparison between the Dry Bulb Temperature (DBT) and Neutral Temperatures (Tn) inside the different ranges, Juarez in summer.

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The similarity of the preferred temperatures found in the cities of the study in both seasons, except in the close range in Winter where there's a bigger extent in Chihuahua, allows us to make joint proposals. For the winter season the strategies are: conventional heating, solar heating, use of thermal mass materials, ventilation control and humidification (figures 13 and 14).

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

5. CONCLUSIONS

Figure 13: Psychometric chart. Winter Chihuahua.

Figure 14: Psychometric chart. Winter Juarez.

For the summer season the strategies are: solar heating in the mornings, solar protection, use of thermal mass materials, selective ventilation, night convective cooling, night infrared radiation and evaporative cooling (figures 15 and 16).

The percentages of votes found inside the ranges of comfort allow pertinent decision taking to accomplish adequate comfort levels and a significant reduction of energy consumption through architectural design. The tolerance of the interior climate indicates that people consider their houses to be in better climate conditions in winter than in summer. Nevertheless, 70% and 78% in winter and 58% and 56% in summer in Chihuahua and Juarez respectively answered that the house conditions were tolerable, which means a high number of people at the acceptance limit of their housings. Among the architectonical proposals produced by this investigation we find the following: • Correct orientation and dimension of openings. • Higher width in walls with high thermal mass materials. • Roof insulation. • Solar protection for windows. • Better ventilation, thus doors and interior walls, and the design of the exterior windows, must be improved. • Higher interior height. • It's necessary to extend the period of study to include the transition season.

6. ACKNOWLEDGMENTS To Chihuahua's Housing Institute for the support and facilities to realize this study.

7. REFERENCES [1]

[2]

Figure 15: Psychometric chart. Summer Chihuahua.

[3]

[4]

[5]

[6] Figure 16: Psychometric chart. Summer Juarez.

Gomez-Azpeitia, G. Bojórquez, P. Ruiz, R. Romero, J. Ochoa, M., Pérez, O. Reséndiz and A. Llamas - Comfort Temperatures inside Low-Cost Housings: Case: Six Warm Climate Cities in Mexico. In: Architecture Energy and the Occupant’s Perspective. Proceedings of the 26th International Conference on Passive and Low Energy Architecture. Les Presses de l’Université Laval, Quebec, Canada, pp. 498503., (2009). J.F. Nicol - Thermal comfort “A handbook for field studies toward an adaptive model"University of East London- London, (1993) ISO 10551 – Assessment of the influence of the thermal environment using subjective judgement scales – Standards Organization, Geneva, (1995). [14] Brager, G. and de Dear, R. Thermal adaptation in the built environment: a literature review. Energy and Buildings, 27, 83-96. (1998). American Society of Heating, Refrigerating and Air conditioning Engineers. ANSI/ASHRAE 55-2004: Thermal environmental conditions for human occupancy. Atlanta. (2004). A. Auliciems - Towards a psycho-physiological model of thermal perception - Int J of Biometeorology (1981), 109-122 xx.x SECTION NAME COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

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[7]

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Low Energy Architecture International. Design tools and techniques. (1997).

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July

2011) PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. ISBN xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

Occupant Behaviour and Energy Performance in Dwellings: A Case Study in the Netherlands Merve BEDIR1, Evert HASSELAAR1, Laure ITARD1 1

OTB Research Institute for Built Environment, TUDelft, Delft, the Netherlands

ABSTRACT: Occupant behaviour is claimed to be an important aspect of energy performance in dwellings, and mostly underestimated before post occupancy. Research conducted on the relationship between occupant behaviour and energy performance applies a variety of data collection methods: reporting [e.g. questionnaire], and observation [e.g. monitoring]. The aim of this paper is to evaluate the different data collection methods about occupant behaviour and the relationship models they propose between occupant behaviour and energy performance, based on a case study in the Netherlands. The first step is a literature analysis. Afterwards, data on occupant behaviour in a case study house in the Netherlands is collected through questionnaire, and monitoring. Results are about [1] an evaluation of the literature on modelling the relationship between occupant behaviour and energy performance, and [2] the comparison of the reported and observed behaviour. Keywords: occupant behaviour, energy performance, dwellings, questionnaire, monitoring

1. INTRODUCTION Research on energy performance of dwellings covers thorough investigation of the behavioural performance in the post occupancy process, as well as the aspects that are involved in the design and building processes. There has been extensive progress on the building physics aspects of energy performance; concerning methods and practices for specification of building geometry, material properties, and external conditions. However, the resolution of input information regarding occupancy is still rather low. Recent and ongoing research attempts to construct models for passive and active occupancy effects on building performance, physical and psychological descriptions of occupancy [1]. The aim of this paper is to evaluate the different data collection methods about occupant behaviour and the relationship models they propose between occupant behaviour and energy performance, based on a case study in the Netherlands. The research questions are: [1] what are the existing methods of modelling behaviour and energy performance? What are their approaches of data collection, how do they process data, and [2] what kind of behavioural information is generated from different methods of data collection? Namely, questionnaire: reported, monitoring: observed. In this paper, ‘behaviour’ is considered as: presence patterns in a space, together with the actual heating [thermostat setting and radiator control] and ventilation patterns [operation of windows, grids, and mechanical systems], and the use of lighting and appliances. Examples of methods of data collection, questionnaire, and monitoring are explained and compared, in terms of the detail level of the collected data, the data analysis, and the relationships they propose between occupant behaviour and energy performance. Different approaches towards modelling behaviour and energy performance relationship in buildings, namely deductive and inductive, are explained in

the literature section. The observed [monitored] and reported [questionnaire] behavioural patterns of the users are generated from a case study house in the Netherlands. The data collected through each method is compared to reveal the differences about the way behavioural patterns are expressed. Results are about [1] an evaluation of the literature on modelling the relationship between occupant behaviour and energy performance, and [2] the comparison of the reported and observed behaviour.

2. LITERATURE Methodology towards modelling the influence of occupant behaviour on the energy performance of buildings follows two main approaches: The deductive and the inductive. This terminology refers to the data processing track and the hierarchy of data used in the analysis. Deductive approach utilizes data on the characteristics of household and energy consumption, and income levels to find statistical correlation between the energy performance and occupant behaviour, and the inductive approach calculates the energy performance of a building based on actual occupancy patterns determined by presence, circulation, and operation of lighting, system management devices and appliances. 2.1. Deductive Behavioural Models Emery et al [13] made a long-term study of residential home heating consumption and the occupant behaviour, where they investigated the lifestyles and behavioural patterns in four identical single-family houses in Washington, between the years 1987 and 2002. They found that the space heating behaviour had been similar and constant, with essentially no difference in the sensitivities and their standard deviations, even though these should have been strongly influenced by the different ventilation strategies of the several families. Space heating behaviour did not change, envelope

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July 2011 PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

spaces, leaving out the amount of days of total absence and the movement in and out of the offices. Hoes et al [11] combine the models of Bourgeois and Tabak, on the use of space and the movement patterns in Esp-r, in order to develop a more articulated model on ‘interaction between the user and its environment and complex mobility prediction’. Tanimoto et al’s [12] research on single dwellings in Tokyo propose a method to predict the peak energy requirement for cooling, combining an algorithm that generates short-term events that are likely to occur in residences, with the stochastic variations in these short-term events. Research about simulating behaviour either by statistics and/or by simulation programs, deal with office spaces on a single zone model, or more zones with less details on use, and more articulation on movement. This underlines the gap of modelling occupant behaviour in residences, in a manner that involves both the use of space and circulation patterns, and in relation to the dwelling energy performance. Climate, household characteristics, energy bills, systems, appliances

Building performance simulation could help a great deal on predicting the influence of occupant behaviour on the energy performance of buildings. For the last decade, research has focused on statistical models of behaviour, since the methods in existing simulation programs lack precise representation of the dynamics of behaviour [9]. Bourgeois developed the sub hourly occupancy control [SHOCC] model that considers windows, lighting, blinds and equipment use and in his study in an office space, where he combined his model on behaviour with the building performance simulation tool Esp-r, he found that the manual control of lighting switches lead to 50% primary energy requirement decrease [7]. However, the SHOCC model is about an office space for two people, so this model lacks the aspects of behaviour of more people and more detailed behavioural patterns in relation to use of other spaces, circulation, etc. Tabak et al [10] developed a model on the use of space and the circulation between spaces [USSU], using actual behavioural information: This model is based on the resource management model [elements: persons, abstract spaces, facilities] combined with an activity schedule. The resource management model includes two different models, one for organization of the people and one for the building. The activity scheduler is made up of 8 different elements: skeleton activities, interaction between activities, intermediate activities, gaps in schedules, overlaps in schedules, joining activities, appropriate location, and required movement time. He validated the model by observing behaviour with Radio Frequency Identification [RFID]. Page et al [6] developed a model for predicting presence in office

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Deductive models

2.2. Inductive Behavioural Models

Survey Questionnaire Interview Statistics Occupant behaviourEnergy performance

Presence Circulation/ operation

Monitoring Observation Statistics Occupant behaviour Simulation

Inductive models

tightness did not seem to degrade and the sensitivities remained constant. Guerra Santin et al [2], conducted a research on the Dutch housing stock based on three surveys applied so far [WOON, KWR, and OTB], and she found that the occupant behaviour affect energy use by 4.2% in the old and 12% in the new stock, while the building characteristics’ share on the energy use is 42% on the total building stock. In her later study, Guerra Santin conducted a further analysis on the OTB sample, which was based on recently built dwellings [after 2000], determining user profiles and the underlying factors of these user profiles. She revealed the underlying groups of occupant behaviour variables as appliances and space, energy intensive, media, ventilation, and temperature comfort, and a relationship with energy consumption was found only for the first three variables. Gaceo et al [8] conducted a study on the Spanish residential stock, comparing the assumed user profiles on indoor temperature preferences from the national standard [assumed] with the ones from a database [actual] that collected data over 700 dwellings in Spain. They found that the assumed user profiles on indoor temperature underestimate the actual by 26% in energy performance, 19% in cooling energy demand and 35% in heating energy demand.

Energy performance

Figure 1: The inductive and deductive models of explaining occupant behaviour-energy performance relationship

In terms of the kind of data used, deductive approach works with general household characteristics like presence, habitual use of systems and appliances, and energy consumption levels depending on energy consumption bills, income, rent levels, whereas the inductive approach works with the actual behavioural data about presence, circulation and operation patterns. The time frequency of the collected data may change from deductive to inductive approach, recording behaviour in the frequency of a period [3 months, a year etc.] in the deductive, and in the frequency of a minute, an hour, etc. in the inductive approach. Survey is the most common method of collecting data in deductive approach, however in the inductive, monitoring and/or observation of behaviour are preferred. In terms of the analysis of the data, deductive approach mainly uses statistical methods, and inductive approach might work with both statistics and simulation. Considering the differentiation of outputs; a big part of the research with deductive approach estimate the influence of

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15

July 2011 PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

behaviour on energy performance from 1 to 12% [2, 3, 4, 5], whereas the behaviour models built up with the inductive approach calculate the impact of behaviour on energy performance as from 20-50% [3, 6, 7, 8].

3. METHODOLOGY The methodology of this research is based on post occupancy evaluation, which includes a questionnaire, monitoring, and investigation on architectural drawings, and EPA [Energie Prestatie Advies] report, and inspection in the case study dwelling. First, the method of data collection on dwelling characteristics and occupant behaviour, in a single family house in the Netherlands, is explained: Monitoring provides data about the presence, lifestyle and the actual behaviour of the occupant on the use of appliances and lighting, and the constant and intermittent electricity consumption levels of the appliances. Data about behavioural patterns at home is also collected by a questionnaire. Inspection, architectural project drawings and the EPA report altogether provide the data about the design and construction characteristics of the case study dwellings; room dimensions, envelope properties, heating and ventilation systems used in the house, and cladding materials. Data analysis is based on the comparison of data collected by monitoring and questionnaire. 3.1. Description of the household and the case study house The household is composed of a couple of a man [63] and a woman [61]. There has been no change in the household for the last year, and the couple has been living in the same house for the last 32 years. Both have lived in the Netherlands since they were born and have university degree, working 32 and 24 hours a week. The couple owns the dwelling, which is a row house and the previous house that they lived in was the same type. The dwelling is constructed in 1928. The house is a typical row house with a net floor area of 123,3 2 m . It has a living room with an open kitchen on the ground floor; one bedroom, two study rooms, and a bathroom on the first floor; a hobby room, a storage area, and a guest room on the third floor. There had been a change in the layout of the house; a 0,8m x 5,66m greenhouse space had been added to the northwest part of the house, to the living room. [Figure 2]. The heating system is HE107 [high efficiency 107%] individual boiler for heating and hot tap water. There is a natural ventilation system, with windows, grids and exhaust ducts in kitchen and bathroom. There are 4 m2 PV panels on the roof, facing southwest. The average yearly gas use for 3 heating, domestic hot water and cooking is 965 m 3 3 [656 m for heating, 310 m hot tap water] [from the 3 EPA report: calculated value] and it was 1223 m in the period of 2007 and 2008 [from the questionnaire: actual consumption value].

Figure 2: Floor plans and cross section of the case study dwelling

3.2. Questionnaire In the case study house, first the monitoring was conducted [in the winter period], and then the occupants were asked to fill in the questionnaire, which was done by the male partner. The data collected through the questionnaire is about dwelling characteristics, household characteristics, primary energy consumption figures, actual behaviour about heating and ventilation behavioural patterns and use of lighting and equipments. A detailed explanation of the data used in this research is given in Table 1. 3.3. Monitoring The case study house in the Netherlands was monitored for 11 days between 10 and 21 January 2010. The aim of monitoring was to observe behaviour about presence, equipment use, lighting behavioural patterns, heating and ventilation management, considering the weather conditions during this period. Data was collected by remote sensors monitoring lighting fixtures, household devices, radiator and indoor temperatures, relative humidity levels, windows, and doors. These sensors are of two kinds: [1] power nodes connected to the lighting fixtures and appliances, and [2] battery nodes monitoring the windows, doors, temperature, and humidity levels in the house. In addition to the data collected in the house, weather data on wind speed, ambient pressure, temperature, humidity, solar irradiance, and rain was collected. The data was transferred with around 6 minutes interval by a GPS system and recorded in a database that could be checked online and simultaneously through a web interface. The sensors were calibrated at the back office.

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July Architecture, 2011 PLEA 2011 - 27th Conference on Passive and Low Energy Louvain-la-Neuve, Belgium, 13-15 July 2011.

Dwelling and household level

Table 1: Data collected through the questionnaire

Dwelling properties Household properties

Heating behaviour

Individual [User] level

Ventilation behaviour

Use of appliances

Use of lighting

-Dwelling type -Number of rooms -Functions of rooms -Household size -Age -Presence -Occupation [rooms] -Occupation [duration] -Heating system type -Radiator use [hours-setpoint] -Thermostat use [hours-setpoint] -Ventilation system type -Use of windows [room-hours-opening] -Use of grids [room-hours] -Use of exhaust [hour-setpoint] -Appliances in the house -Hours that appliances are used, daily -Hours that appliances are used, weekly -Number of lighting fixtures in the living room -Number of lighting fixtures in the rest of the house

4. RESULTS The questionnaire applied to the household provides information about the lifestyle of the occupants. In addition, monitoring during a week, gives further details about the discrete behaviour of the users about the use of spaces and appliances. 4.1. Reported Behaviour in the Case Study House Presence [Figure 4]: During the week, the man is at home between 19.00 and 07.00, and the woman is at home between 17.00 and 07.00. The living room is occupied between 18.00-19.00 and 23.00-24.00 by 1 person and 20.00-21.00 by 2 people. The kitchen is occupied between 06.0007.00, and 19.00-20.00 by two people, and 17.0018.00 by one person. The couple occupies the bedroom between 24.00 and 06.00. During the weekend, the couple is at home between 13.00 and 10.00. The living room is occupied between 16.0017.00 by 1 person, 17.00-21.00 and 08.00-10.00 by 2 people. The presence pattern in the bedroom at the weekend is different than the weekday pattern, which is, between 23.00 and 08.00. The couple spends time in their study rooms, one for two hours [21.00-23.00], and the other for an hour [21.0022.00] in the study room, and for another hour in the hobby room [22.00-23.00].

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Presence in living room during the week

Presence at home during the weekend

Presence in living room during the weekend Figure 4: Presence patterns at home during the week

Heating Control [Figure 5]: The heating system in the house is controlled by the master manual thermostat in the living room, and slave radiators. During the weekdays, there are two reported patterns of thermostat control: Weekdays except Thursday, the thermostat is at 13 °C between 22.00 and 16.00. Between 16.00 and 18.00 the thermostat is at 15 °C, between 18.00 and 19.00 at 16 °C and between 19.00 and 23.00, 17 °C. Thursdays, the thermostat is at 13 °C between 22.00 and 06.00. Between 06.00 and 09.00 the thermostat is at 14 °C, 09.00-17.00 at 15 °C, 17.00 18.00 at 16 °C, and 18.00-22.00 at 17 °C. At the weekends, the thermostat is at 13 °C between 22.00-08.00, 15 °C between 08.00-10.00, 13 °C between 10.00-12.00, 15 °C between 12.0015.00, 16 °C between 15.00-17.00, 17 °C between 17.00-20.00, and 18 °C between 20.00-22.00.

Thermostat control in the week [exc. Thursday]

Thermostat control on Thursday

Thermostat control at the weekend Figure 5: Thermostat control patterns during the week

The radiator has a control system of 1-5 and off. In the living room, kitchen, and bathroom, the radiators are always on set 5. In the attic, bedroom, and guest room, the radiators are always off. In the study room 2, the radiator is always on level 3, in the study room 1 the radiators are on 4 between 00.00 and 19.00, and on 5 between 19.00 and

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15

July 2011 PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

00.00. In the hobby room, the radiators are on 1 between 00.00 and 18.00, and on 5 between 18.00 and 00.00. The weekend pattern of radiator control is the same with the weekday pattern. Use of thermostat settings displays that non presence means 13 °C, and presence means 15 °C -least, and 17 °C -most. The use of the radiator taps is less, because the temperature in house is regulated mostly by the master thermostat. The thermostat setpoint is changed very frequently. Ventilation Control: For ventilation, existing system in the dwelling is natural ventilation, namely windows, grids, and exhaust duct. The couple’s previous house had only windows for ventilation. The windows are operated as either always open or closed. Only in the bathroom, the windows are always kept open at a chink. In the winter, the windows are kept open all day in the attic [storage], bedroom, guest room, and hobby room. In the rest of the rooms, the windows are kept closed. In the summer, the living room windows are kept open for 2 hours in the morning, between 06.00 and 08.00, and for 6 hours in the evening, between 17.00 and 23.00. The windows are kept open all day in the attic [storage], bedroom, guest room, and hobby room. The study room 1 windows are open between 06.00 and 08.00, and 20.00 and 00.00. The grids are controlled in the same way in the winter, and in the summer: the living room, kitchen, study rooms’ grids are always kept open, and the others are always kept closed. Unlike the operation of the thermostat, ventilation behaviour in the dwelling seems quite constant. Lighting and Appliances: The reported behaviour on the use of appliances is given in Table 2. In addition to these patterns mentioned in Table 5, 3 loads of washing are made per week, in 30 °C, 40 °C, and 50 °C. 3 energy-saving lamps exist in th e living room, and 1 energy-saving lamp in the rest of the house. There are 4 halogen-lamps in the living room and 8 in the rest of the house. 3 devices are always on the stand by mode in the living room, and 9 of them in the rest of the house. 4.2. Observed [Monitored] vs. [Questionnaire] Behaviour

Reported

The data obtained about behaviour through monitoring displays that the two weeks’ data on the use of space are almost the same in Week 1 and Week 2. So it could be said that the behaviour is consistent. The data collected in the bedroom about use pattern have not been able to be followed efficiently, through lighting and appliances, because of monitoring drawbacks. Lifestyle and use of spaces: - Following the data obtained by both the questionnaire and the monitoring, it could be said that the second floor is the most occupied floor of the house. - In the questionnaire, presence at home at the weekend is mentioned as between 13.00 and 10.00; but, further explanation on the activities in this period is not mentioned. Monitoring data shows that

the study room 2 or the hobby room is occupied by the female partner between 21.00 and 24.00 during the week, and between 13.00 and 16.00 during the weekend. - Behavioural patterns differ between an ‘at home’ day than a ‘not-at home’ day. Same differentiation cannot be observed for week and weekend behavioural patterns. For example, during an ‘at home’ day in the week and at the weekend, the computer is used for 2 hours and 58 minutes on average, but during a ‘not-at home’ day, in the week and at the weekend, the computer is used for 32 minutes on average. Same pattern could be observed with the use of wireless internet. - Data collected by monitoring proposes a more arbitrary use of kitchen and living room, unlike it is mentioned in the questionnaire. Spatial organization might be an important aspect here, since there is not an exact spatial differentiation of the kitchen and living room. - Monitoring data proposes the occupation of the kitchen as, between 08.00 and 09.00 in the morning, not between 06.00 and 07.00 as mentioned in the questionnaire. Table 2: Reported and monitored use of appliances

TV Comp./monitor Comp./laptop Stereo/radio Wirel. internet Dvd player Disc recorder Wirel. phone Coffee mach. Toaster Elec. oven/grill Gas oven Exhaust hood Fridge Freezer Wash machine Flatiron Iron

Reported

Monitored

100 60 NA 15 90 60 1440 9 10 10 5 15 1440 1440 5 3

-

Day [min]

Week [hours]

10 8 1 2 1 5 5 148 0,5 1 1 0,5 2 148 148 180 0,5 0,2

Day [min]

32/238

-

23/130

34/NA 122 Cont. -

-

Week [hours]

16,13 9,09 238 14,14 Cont. -

Lighting and appliances: The computers are used twice as much as stated in the questionnaire. Wireless telephone is used for a longer period than it is mentioned in the questionnaire. The exhaust hood could also said to be used longer, but this appliance is monitored together with the light in the kitchen, so it has to be confirmed with further monitoring. Some of the appliances listed in the questionnaire are not monitored, so an exact comparison cannot be made between the reported and monitored behaviour in terms of the use of appliances.

5. CONCLUSIONS The research questions addressed in this paper are: [1] the existing methods of modelling behaviour

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. and energy performance, and [2] what kind of behavioural information is generated from different methods of data collection. Regarding the first question, it appears to be that the inductive models estimate the influence of occupant behaviour on the energy performance to be more than the deductive models estimate it to be. Another point is that the deductive approach works with the behaviour data collected with a higher time frequency, which gives more information about the habitual behaviour. This might be risky considering that it is not known how influential habitual and/or discrete behaviour is on the energy performance of the dwelling. On the other hand, the inductive approach has a drawback of working with a high detail level, which is hard to obtain, especially working at household level. Collected data through monitoring and questionnaire provide insight to occupant behaviour. In reference to the reported data, heating control behaviour seems strongly related with the lifestyles of the occupants. This could be observed through the thermostat control pattern in relation to sleeping hours, and departure and arrival schedules of the occupants. Besides, the thermostat use shows a wide variety of operation, whereas the radiator taps are mostly kept at a certain set. In terms of the control of the ventilation, a less presence-dependent but constant operation pattern is observed. The tendency in reporting behaviour is to express about habitual behaviour. Monitoring, on the other hand, gives more information about discrete behaviour. In other words, the non-repetitive actions could better be observed via monitoring. In addition, more difference is observed in behavioural patterns on ‘at home’ and ‘not-at home’ days than weekdays and weekends. The differences between reported and observed behaviour could be important in terms of the calculations of occupant’s influence on the energy performance of dwellings. This paper is about ‘direct behaviour’, namely, presence, control of lighting, appliances, heating, and ventilation. However, the other side of the behaviour mentioned as ‘indirect’ in the literature [reaction to the changes of comfort levels] rises the question of an analysis in terms of direct and indirect behaviour. In this respect, it could be predicted that monitoring can provide more detailed information about indirect behaviour.

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6. REFERENCES [1] Mahdavi, A. Pröglhöf C. (2009) User behaviour and energy performance in buildings. Internationalen Energiewirthschaftstagung an der TUWien, Vienna, 1-13 [2] Guerra Santin, O. Itard, L. Visscher, H. (2009) The effect of occupancy and building characteristics on energy use for space and water heating in Dutch residential stock. Energy and Buildings v. 41, is. 11, 1223-1232 [3] Andersen, R. V. (2009) Occupant behaviour with regard to control of the indoor environment, PhD thesis, Department of Civil Engineering, Technical University of Denmark [4] Vringer, K. (2005) Analysis of the ernergy requirement for household consumption Milieu en Natuur Planbureau, Bilthoven. Proefschrift. ISBN: 90-6960-130-3 [5] Tommerup, H. Rose, J. Svendsen, S. (2007) Energy-efficient houses built according to the energy performance requirements introduced in Denmark in 2006 Energy and Buildings 39-10, October 2007, 1123-1130 [6] Page, J. Robinson, D. Morel, N. Scartezzini, J. –L. (2008) A generalized stochastic model for the simulation of occupant presence. Energy and Buildings 40, 83-98 [7] Borgeois, D. (2005) Detailed occupancy prediction, occupancy-sensing control and advanced behavioural modeling with-in wholebuilding energy simulation PhD Thesis, I’Universite Laval, Quebec [8] Gaceo, S.C. Vazquez, F.I. Moreno, J.V. (2009) Comparison of standard and case-based user profiles in building’s energy performance simulation. In 11th International IBPSA Conference. Glasgow, Scotland (27-30 July) 584-590 [9] Rijal, H:.B. Tuohy, P. Humpreys, M.A. Nicol, J.F. Samuel, A. Clarke, J. (2007) Using results from field surveys to predict the effect of open windows and thermal comfort on energy use in buildings Energy and Buildings 39 [7] 823-836 [10] Tabak, V. de Vries, B. Dijkstra, J. Jessurun, J. (2006) Interaction in activity location th scheduling. In Proceedings of the 11 International Conference on Travel Behaviour Research, Kyoto, Japan, 2006 [11] Hoes, P. Hensen, J.L.M. Loomans, M.G.L.C. de Vries, B. Bourgeois, D. (2008) User behaviour in whole building simulation. Energy and Buildings doi:10.1016/j.enbuild.2008.09.008 [12] Tanimoto, J. Hagishima, A. Sagara, H. (2008) A methodology for peak energy requirement considering actual variation of occupant’s behaviour schedules Building and Environment 43, 610-619

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Occupant interaction with the interior environment in Greek dwellings during summer Aikaterini DRAKOU1, Aris TSANGRASSOULIS1 , Astrid ROETZEL2 1

2

Department of Architecture, University of Thessaly, Volos, Greece School of Architecture and Building, Deakin University, Geelong, Australia

ABSTRACT: User behaviour significantly affects energy consumption simulation estimates, which can consequently influence architectural design decisions at an early stage. Different regional behavioural patterns could, therefore, hinder the applicability of certain architectural and environmental strategies. Through questionnaires analysis and field studies, this study investigates the pattern use of manual control of windows, shading and air condition units, in residential buildings in Greece, during summer. Initial findings of the analysis indicate significant interaction of Greek residents with the building shell, in their effort to maintain comfort. Keywords: comfort, occupancy

1. INTRODUCTION Building occupants interact with the building shell and its systems in order to satisfy their needs for comfort. This interaction can either benefit the utmost from the sustainable design techniques of the building or result in higher energy consumption due to lifestyle choice. It is, therefore, important to take occupant interaction with the interior environment into account when designing buildings. For example, different building construction techniques may be inconsistent with regional behavioural patterns. The common practice of highly energy-efficient buildings promotes minimum interaction of the occupant with the building shell, while according to Leman and Bordass [1] people become more tolerant when they are able to control their environment. However, there is little reported on the subject from Greece, especially in residential environments. In most Greek dwellings natural ventilation is used throughout the year, while the use of air conditioning, although limited, is rapidly increasing [2]. In this context, the present study investigates occupant behaviour in Greek dwellings and apartments in summer, through subjective surveys (questionnaires) and field studies. The aim of the study is to analyse the pattern use of manual control of windows, shading and air condition units, with the aim of correlating this pattern with indoor and outdoor conditions in a later phase of this research.

2. RESEARCH METHODS The climate in Greece is typical of the Mediterranean climate: mild and rainy winters, relatively warm and dry summers and, generally, high solar radiation throughout most of the year. In terms of climatology, the year can be broadly divided into two main seasons: the cold and rainy period lasting from mid-October until the end of March, and the warm and non-rainy season lasting from April until September. The hottest months in Athens (longitude: 23.7, latitude: 38, Greek climatic zone B),

are July and August, with monthly average o temperatures of 27.5 C. The annual average temperature is 18.55 °C, which makes this city one of the warmest in Europe [3]. In combination with the dense urban grid, the satisfaction of high cooling load is particularly difficult. The study consists of two parts: a) subjective surveys (questionnaires) and b) field studies. The study was conducted in the summer (July to September) of 2010, using samples of respondents and dwellings from the four climatic zones of Greece. 2.1. Questionnaires Greek residential building stock is concentrated mainly in cities, where thermal comfort during summer is a challenge due to the dense urban grid, thus, a sample of respondents scattered throughout cities all over Greece was used. The connection to the sample was produced by university students coming from different parts of the country. The questionnaires were delivered to the subjects either in a hard copy or in a digital format by email. The subjects were given one week to fill in the questionnaire, which aimed to investigate subjective sensation, preference and satisfaction with regard to the indoor environmental conditions and highlight patterns of occupant behaviour concerning a typical summer day and not the day of the survey. The questionnaire was divided into ten sections: building information, window size, ventilation, IAQ, view, shading, use of daylight and artificial lighting, thermal comfort, use of cooling systems, behavioural patterns in using various controls and their efficacy on a typical summer day. It was a comprehensive questionnaire to facilitate a better insight into the occupants’ interaction pattern with the building shell and their level of satisfaction with the current indoor environmental conditions. In order to measure sensation, satisfaction and preference either a fivepoint scale ranging from (-2) to (+2) with neutral (0) in the middle, or a seven-point scale from (-3) to (+3) with neutral (0) in the middle was used. For example, for thermal preference the five-point scale was as follows: much cooler (-2), a bit cooler, no change (0), a bit warmer and much warmer (+2), while for

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humidity sensation, the seven-point scale was as follows: very dry (-3), dry (-2), almost dry (-1), neutral (0), slightly humid (+1), humid (+2), very humid (+3). Of the questionnaires distributed, 109 have been returned. The length and the complexity of the questionnaire probably caused some difficulties to the respondents. . 2.2. Field studies In addition to the questionnaire analysis, short term field studies were carried out in a number of houses in four climatic zones of Greece. Window status, shading control, occupant behaviour, indoor (temperature, relative humidity) and outdoor climatic conditions were monitored, in an attempt to investigate how Greek houses and residents behave during summer. Monitoring was carried out in August and September 2010. Temperature measurements were taken indoors and outdoors at time intervals of 1 min. Greek families typically spend most of their time in the living room, which is consequently the space where people interact most with the building envelope, so the analysis focuses on the living room conditions. A temperature and humidity data logger was used in living rooms and on balconies to measure the indoor and outdoor thermal conditions. The data loggers were placed at the centre of each room at a height of approximately 85cm. The data logger on the balcony was put in a place protected from direct sun, rain and wind, and it was not in contact with any other surface. The behavioural pattern of changing the state of windows, shading and cooling systems has been derived from the residents’ notes on their daily routine, as declared.

3. RESULTS AND DISCUSSION 3.1. Location, building types, envelope characteristics and sample profile The survey sample consists of 44 male and 65 female participants (40.4% and 59.6% respectively). Approximately 50% of the participants are between 40 and 60 years old, 42% is in the 20 to 40 year old age group and only 8% are over 60. The respondents come from 14 cities of Greece distributed across all four different climatic zones of the country (Zone A: 14.7%, Zone B: 24.8%, Zone C: 39.4%, Zone D: 21.1%). The predominant (64%) type of residence of the survey sample is an “apartment”, which is representative of Greek urban reality, while 19% of the respondents live in a “detached house” and 17% in a “house in contact with other buildings”. The majority (approximately 60%) of the residences are located in the city centre (48% apartments, 7% houses in contact with other buildings, 5% detached houses), whereas the remainder are located in the suburbs (33%) and in the countryside (7%). Building age is an important factor as it may be an indication of the construction type. For example, a Greek building over 30 years old has no thermal insulation, as the regulation for thermal insulation in

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Greece was not established until 1979. The age of residences in the sample is distributed as follows: 34% less than 10 years old, 45% between 11-30 years old and 21% over 30 years old. The significant majority (96%) of the participants’ houses are conventional Greek constructions, i.e. concrete post and beam construction with cement plastered and brick in-fill walls. The “Other” category (4%) included a mix of conventional construction with steel or a mix of stone construction with timber. 66% of the subjects stated that the period they have lived in their current house is “more than 5 years”, 27% chose “between 1-5 years” and only 6% “less than a year”. This distribution suggests that the participants have already formed a behavioural pattern for the house they live in, so their responses have a certain significance. Natural ventilation was used for IAQ in all survey residences, while some occupants owned AC units which were used for cooling. 3.2. Respondents’ evaluation of their indoor environmental conditions Occupants were asked to evaluate their indoor environment during summer by expressing sensation, level of satisfaction and preferences for certain conditions. Fig. 1 shows that occupants, on average, are neither satisfied nor dissatisfied with their indoor temperature during a typical summer day. The standard deviation of the sample though, is large, indicating a variety of satisfaction levels among the occupants. The subjective temperature sensation, on average, is neutral to warm, while all of the respondents in the survey prefer to be a bit cooler or much cooler. Concerning the indoor air quality the sample is satisfied, but the standard deviation of the humidity sensation vote (close to neutral on average), indicates some complaints about humid, mainly, or dry air. Even though all the occupants are not dissatisfied with the window size, they would prefer a larger one. The daylight levels, on average, are perceived as acceptable to high, but the standard deviation of the sample is large, indicating various levels of daylight. Similar comments apply to view satisfaction, while noise levels in residences appear to be acceptable to low. The main observation is that, on average, the participants characterise the majority of the indoor environmental conditions, as neutral, with a slight trend towards good, but a large standard deviation is noticed. Moreover, it is clearly stated that all the occupants would prefer to feel “cooler” to “much cooler” during a typical summer day, even though their mean temperature satisfaction vote is close to acceptable. The mean overall satisfaction vote of the participants for the house as a whole (taking into account any possible parameter and not only indoor environmental conditions) tends to be “slightly satisfied”.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 2: Distribution of reasons for window opening during summer.

Figure 1: Respondents’ evaluation of their indoor environmental conditions. (Mean values with standard deviation)

3.3. Reasons for occupant interaction with windows As residential buildings in Greece are, on average, naturally ventilated, the control of windows and balcony doors is the main way to achieve thermal comfort and good IAQ during summer. Hence, the window opening type plays an essential role in the ventilation rates, and consequently in the user behaviour. A wide variety of window opening types is available. Sliding and side hung windows are the most common type used in Greece. In the survey, 59% of the participants use sliding windows, while 34% side hung windows. The usual percentage of window opening during summer is 50-59% (43% of responses) and 100% (24% responses). As it was not clearly defined in the question whether the percentage of opening refers to the whole glazing surface or to the feasible opening depending on the window opening type, some of the responses of 50% opening may correspond to the sliding windows, indicating maximum use of the feasible opening area of the window. As fig. 2 shows, the primary (67%) reason for opening a window during summer is the improvement of IAQ. A secondary reason is the decrease in indoor temperature (32%), while only 1% voted for acoustical connection to the external environment. The results reflect the importance of good IAQ to the occupants. On the other hand, the prevention of overheating is, by far (64%), the most important reason for closing a window during summer (fig. 3). Occupants are trying to maintain thermal comfort by using the building’s high thermal mass and by minimising the heat gains through open windows. Protection from external noise is another important reason for closing the window. 3.4. Ventilation Regarding the possibility of cross ventilation, 79% reported that this is possible, while 21% not. Where cross ventilation is possible, it is commonly used daily (72%), or at least “often” (4-6 times/week)

Figure 3: Distribution of reasons for window closing during summer.

(17%). The majority (43%) use cross ventilation in the morning, primarily to improve IAQ (32%) and secondly for thermal comfort (11%) (fig.4). On the other hand, occupants who prefer night cross ventilation (31%), are more interested in improving thermal comfort (28%) than IAQ (4%). Therefore, the predominant pattern derived from the study is daily use of cross ventilation during the morning to improve IAQ.

Figure 4: Distribution of cross ventilation with the time of day and the reason.

Apart from cross ventilation, night ventilation seems to be a common passive measure to provide thermal comfort during the day in the summer period. 56% of participants use night ventilation daily and 21% “4-6 times per week” (fig. 5). Where “no use” or “rare use” of night ventilation was reported (9%), security reasons and use of AC during the night were responsible.

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Figure 5: Distribution of the use of night ventilation

3.5. Frequency of window alteration depending on the time of day Fig. 6 presents the frequency of altering the window state during a typical summer day and how this behaviour is distributed across different times of the day. A strong interaction of occupants with windows is noticed, as 45% of the sample change the window state “2-3 times/day”, 30% “more than 3 times/day” and only 16% “1 time/day”. Thus, modern Greeks still interact considerably with the building shell, trying to adapt to the changing environmental conditions throughout the day. There is a tendency for occupants to change the window state mostly when they wake up (31%), and slightly less when they spend many hours in the house (26%). A smaller portion of the participants (19%) alter windows when they leave the house. On the other hand, there is a dependency between the frequency of window use and the time of day. Therefore, the majority of participants that control window state 2-3 times/day, interact with the windows mainly when they spend many hours in the house and not in the morning, as the largest part of the sample reported. Consequently, it is concluded that the amount of time spent at home affects the time of day that occupants interact more with the windows.

increasing daylight levels (39%) and keeping visual connection with the external environment (10%). A small proportion of the subjects (7%) stated that they never open the shading during summer. On the other hand, the predominant reason for closing the shading is to achieve a decrease in indoor temperature (69%), followed by a decrease in daylight levels (12%). Other secondary reasons are “glare protection” and “more privacy”. Therefore, it is noticed that opening of the shading is determined by IAQ, as is window opening, while the closing of shading is determined by indoor temperature, as is the case of window closing. The frequency pattern of shading use is similar to that of window use. The majority of the occupants (49%) change shading state 2-3 times/day, 26% once per day, 13% 1-3 times/week, 9% rarely or never alter it, but only 4% control the shading “more than 3 times/day”. This 4% is significantly smaller than the corresponding 30% concerning window use. So even though the majority of the occupants control both windows and shading 2-3 times/day, the frequency of interaction with windows is considerably higher in total.

Figure 7: Shading alteration frequency with time of use.

Figure 6: Window alteration frequency with time of use.

3.6. Use of shading – reasons and pattern of use According to the survey participants, the most important reason for opening the shading is to facilitate room ventilation (42%), followed by

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Fig. 7 shows the distribution of the frequency of shading use according to the time of day. People who adjust the shading 2-3 times/day do it mostly when they wake up (18%) and secondly when they spend many hours at home (14%). In contrast, people who stated that they change the shading once per day, mainly do it when they spend many hours at home. Occupants that interact most with the shading (only 4% of the sample), more than 3 times/day, do it mainly when they return home (2%). Correspondingly, results for the time of day that people control most their shading, irrespective of the frequency of shading use, show that 31% of occupants control the shading when they spend many hours at home, and 26% when they wake up. Most of the sample (71%) shade, the 75-100% of the window surface. 3.7. Cooling systems Regarding cooling systems, 70% of the survey subjects reported that they have AC in the house,

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

approximately 45% have a type of fan and only 8% do not have a cooling system (fig. 8). Fig. 9 shows that July and August are the months that cooling systems are most in use. As expected, August accounted for the largest percentage of use for both AC and fans. Early afternoon hours (13:00–17:00) seem to be the time of day with least thermal comfort as the majority (68%) of the subjects use cooling systems during this period (fig. 10). The following hours (17:00-20:00) account for 41% of the cooling use, while there is a significant proportion of the occupants (28%) that make use of cooling systems during the night (24:00-08:00).

Figure 11: Distribution of AC use during the night according to frequency of night ventilation and perceived level of humidity.

Figure 8: Distribution of cooling systems.

Figure 12: Preferred and maximum acceptable cooling setpoints (average and STD.)

4. MONITORING Figure 9: Distribution of cooling systems use by month.

Figure 10: Use of cooling systems by time of day.

Fig. 11 describes the relationship between frequency of night ventilation use, subjective sensation of humidity of the air and use of AC during night hours. The most interesting remark is that 50% of the occupants that stated they use night ventilation daily also use AC during the night. An explanation might be given by their sensation vote for humidity of the air, which is mainly perceived as neutral (33%). These subjects simultaneously use AC during the night to improve indoor temperature and night ventilation to maintain IAQ. According to fig. 12, the mean temperature set in AC is 24,53oC (STD= 2,56), while the mean highest temperature at which they are willing to set AC in o order to save energy, is 26,33 C (STD= 1,88). The difference between the means is only 1,8oC which indicates that survey subjects are not ready to compromise their comfort in order to save energy.

In addition to the questionnaire analysis, a short term monitoring study measuring air (accuracy ±0.5°C (-20 to 50°C)) and surface temperatures, relative humidity and illumination levels was carried out, during summer conditions, in a number of houses. To achieve this, small sensors were placed around the house for a period of at least two days. The scope of this work was to verify the results of the questionnaire analysis, comparing the responses with the interior conditions when some change in openings occurred. The example below presents results from a naturally ventilated 80 m2 flat in Greek climatic Zone B, built during 2000 (fig. 13). The building is well protected by other buildings to the south and north with east/west facing openings, shaded by large balconies.

Figure 13: View of the house (Source: Bing maps)

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6 September

Figure 14: Temperature monitoring over two successive days.

The graph in fig. 14 presents two successive days with the first having all openings closed and the residents absent, while in the second openings are modified by occupants. The indoor temperature o remains steady at 28,3 C when the flat is unoccupied with openings and shutters closed - an expected behaviour, since the building has high thermal mass and the internal and external gains remain stable. With the arrival of the occupants, the windows and shutters are opened and ventilation thus reduces the indoor temperature. However, this reduction is quite small (~10C), despite cross ventilation being used, as a consequence of the building’s heavyweight construction and the protection provided by adjacent buildings and large balconies. Multi-storey apartment buildings in a row are the typical type of residence in Greece. A dense urban grid comprised by this type of building decreases the effectiveness of natural ventilation to provide thermal comfort. Consequently, the pattern described in fig. 14 might explain the simultaneous use of AC units and openings during the night, which arose from the questionnaire analysis, since natural ventilation alone cannot significantly decrease temperature on calm days.

5. CONCLUSIONS This study presented some of the initial findings of a questionnaire and field study analysis on the occupant interaction with the interior environment in Greek dwellings during summer. On average, the participants characterise the majority of the indoor environmental conditions, as neutral, with a slight trend towards good, but a large standard deviation is noticed, probably because of the relatively small size of the sample. Even though the mean temperature satisfaction vote is close to acceptable, all the survey occupants prefer to feel “cooler” to “much cooler” during a typical summer day. It has also been found that most occupants control window state and shading 2-3 times/day. Improvement of IAQ is the main reason for window opening, while facilitation of room ventilation constitutes the main reason for opening the shading. Prevention of overheating is the principal reason for

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closing windows or shading. The majority of the occupants control both windows and shading 2-3 times/day, but the frequency of interaction with windows is considerably higher in total. Survey participants prefer to use cross ventilation daily, during the morning, to improve IAQ, while daily use of night ventilation is preferred too. Use of AC is increasing in Greece, with 70% of the survey subjects owning AC units in the house. The paradox is that these subjects simultaneously use AC during the night (to improve indoor temperature) and night ventilation (to maintain good IAQ). Further research is needed, however, to verify the preliminary results of this survey. The difficulty of questionnaire surveys and field studies, especially in residences, in Greece should be taken into account for further research. Because of the lack of previous studies for occupant behaviour in residences in Greece, the results of this study may form a foundation for the monitoring of the evolution of user behaviour in Greek houses, as architectural thinking and practice change. They could also form a basis for a better understanding of the interaction of the resident with the interior environment, which can help improve energy simulation estimates. It could also be investigated whether different construction techniques (such as mechanically ventilated low thermal mass dwellings) are affected by the Greek pattern of occupant behaviour.

6. ACKNOWLEDGEMENTS The work of this paper has been funded by the Bodossaki Foundation. The authors would like to thank the people who participated in the survey.

7. REFERENCES [1]

A. Leaman, B. Bordass, Productivity in buildings: the ‘killer’ variables, Building Research & Information 27 (1) (1999) 4–20. [2] Plan of Action of Energy Performance. In the frames of Directive 2006/32/EC Athens, June 2008 [3] www.hnms.gr

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Exploiting adaptation and transitions Learning from environments beyond the boundaries of comfort Natalia Kafassis1 1

Environment and Energy Studies Programme, Architectural Association, London, UK

ABSTRACT: The research presented here is originally work submitted as a post-graduate dissertation in Sustainable Environmental Design from the Architectural Association. The object of this dissertation was the investigation of transitions and the way they are experienced by users according to criteria of adaptation, comfort and pleasure, mostly from a thermal point of view. The literature review, revealed the importance of variability in conditions and of stimulating milieus as a necessary condition of successful environments. According to this, design implications linked with spatial and temporal diversity were introduced, most important of which are transitional spaces. The second and most important part of the study was the testing of different types of transitions via simple experiments, resulting in their experiential (comfort, stimulation and pleasure related) assessment. The final outcome was the production of generic conclusions related to the experience of transitions, the categorisation of transition types according to their potential to accommodate different behavioural requirements related to a transitional spaces’ programme and finally the linkage between different transitional spaces to their most appropriate transition type (as thermal and visual sequencing) to provide comfort and delight.

 

Keywords: adaptation mechanisms, transitions, thermal and visual comfort, delight.

1. INTRODUCTION This study is the final part of a year-long research strategy on the potential of enriching the architectural and sensorial experience of a building through the voluntary exploitation of environmental parameters, particularly in transitions. As Hawkes [1] states: “the most memorable and remarkable architectural environments often break the bounds of convention. They discover the combinations of environmental elements that, by some particular emphasis or relationship, enrich the experience of inhabitation”. This sentence very elaborately links the crucial research topics of this study: the “remarkable” combination of environmental elements is related to the perception of variability in conditions, and the experience of inhabitation leads to the topic of human reaction to environmental elements, relating the topic to adaptation mechanisms. The investigation of transitions will be the main research topic of this piece of work, and its focal point will be to determine the implication of different transition types, as sequencings of environmental conditions, in the perception of comfort and the pleasurable appreciation of space, all of which participate in the architectural and sensorial experience of buildings.

2. THEORETICAL BACKGROUND 2.1. Concepts and principles Various parameters affect thermal comfort and adaptability [2]. They can be distinguished in environmental variables (air temperature, radiant temperature, relative humidity, air velocity, etc), and occupant parameters, separated in organic (age,

sex, state of health, national characteristics, etc.) and external (human activity level, clothing, social conditions). The most important characteristic of thermal interaction between man and environment, though, as underlined by Herschong [3], is that thermal interaction is never neutral; it involves a change in body temperature. Thermal nerve endings are heatflow sensors; what they tell us is how we lose or gain heat. It’s from the change in our own body temperature that we are able to judge the temperature of an external object. Herschong continues by explaining that thermal sensors can experience a type of ‘fatigue’. The nerves are more attuned to notice change than steady state conditions in the environment. According to Bell, this can be explained physiologically by receptors firing less frequently upon repeated exposure to a stimulus. [4] This is the basis of human adaptation mechanisms. Physiological neutrality (thermal equilibrium), while being a precondition for it, does not necessarily mean comfort. Other factors are also involved in the process of adaptability like past experience, sociocultural factors, habits, expectation, etc. [5] Psychological factors are thus at least as important as physiological ones. According to Herschong there is an underlying assumption, being that “the best thermal environment never needs to be noticed”. Despite admitting the possibility of variation and a wider comfort zone, the idea of neutrality as a thermal optimum persists. However, well-being is beyond comfort, the environment must also be stimulating. A Study by Mudri [6] has shown that comfort and pleasant conditions might actually be in conflict. She argues that a comfortable environment,

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with an absence of visual tensions, might also be perceived as monotonous, dull or depressive. What separates pleasure from comfort is the presence of some environmental tension, a sensorial stimulation. Already in 1973, Fanger claimed that it is not always ideal to have constant thermal environments because it can increase fatigue, lower stimulation and performance, etc. This phenomenon is called “climate monotony” and is often the risk when opting for centrally controlled, artificially maintained thermal conditions. Alison Kwok[7] warns of “thermal boredom”. Since comfort is a psychological phenomenon, and human beings have a need for sensory stimulation, she argues for variations in thermal environment and fluctuations in internal temperatures to counteract this. Variability is thus a characteristic of environments which is not only tolerated but actually preferred. Pushing one step further is the theory considering the human appreciation for extreme environmental conditions. Not only neutrality is to be excluded, there is also scope to accept a certain degree of thermal stress. There are numerous examples in our everyday life which justify this hypothesis, which reveal the enjoyment of extreme thermal experiences. Some anecdotal examples of these cited in Kwok are: Sitting in front of a fire (dramatic radiant asymmetry), Sunbathing at the beach (then jump into the cold ocean to cool down), Sauna and hammam baths that push our core temperature towards the thresholds of safety and tolerance. After reaching those limits, running outside and roll in the snow or jump into the frozen lake, ultimately forcing our core temperatures in the opposite direction. The question is: What makes this out of comfort experience pleasurable? Herschong notes that places of thermal extremes have their opposites right next to each other. For physiological reasons, the movement from one to another allows maintaining thermal balance and thus provides the safety to enjoy fully both extremes, without threatening our health. Sauna and Turkish baths fans also claim that it improves one’s health and builds resistance to cold and heat. The second reason is aesthetic. Each extreme experience is made more acute by contrast to the other. This proves that thermal balance doesn’t have to suggest steady neutral conditions. The question now is whether there is the potential to use this trend in everyday life and to what extent. Architectural design can influence thermal sensations. The careful consideration of environmental parameters during architectural conception can have a huge impact in the perception of space and the feeling of well-being of its users. Not to mention that, from an aesthetic point of view, this can also be a way to enrich the architectural experience of buildings and bestow them a higher significance. Environmental diversity was proven as the principal way to give simultaneous varied thermal conditions to choose from.

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Merghani[8] analyses the effects of spatial diversity (diversity between spaces) on thermal satisfaction and energy consumption. If we increase the range of thermal zones available within a building, the adaptive opportunity of the occupants increases. A way to promote spatial diversity with a dynamic relation to external conditions, are transitional spaces. These mitigate and sequence sudden temperature drifts by providing gradual step changes in environmental conditions. Transitional spaces also increase the number of microclimates available simultaneously to suit different comfort needs. 2.2. Research precedents A number of studies based both on experiments in climate chambers and on fieldwork have dealt with the subjects discussed above. In 1990, Knudsen and Fanger [9] investigated the impact of temperature step-changes on thermal comfort through a series of experiments in climate chambers, which exposed subjects to thermal up-steps and down-steps. These studies revealed: 1) Step changes of operative temperature are felt instantly and response is usually stronger in down-steps than up-steps. 2) There is greater sensitivity to cold steps than to warm steps. 3) The speed of adaptation to new thermal conditions depends on whether the change is towards or away from comfort. 4) It is the rate of change of the temperature that is important in comfort rather than the actual temperature. 5) warm steps are better than cold steps since they are more likely to trigger behavioural responses. Field research by Nicol and Pagliano [10] indicates the extent and rapidity of adaptation and thus of the acceptable temperature drifts within a given period. They consider adaptation, both as a psycho-physiological mechanism but also from a behavioural approach, with people making adjustments to accommodate to the conditions (adaptive opportunity). During a single day, temperature drifts should vary little from the customary temperature, meaning no more than +/2K. More than this is likely to attract attention and cause discomfort. The cumulative change of temperature over a week should not exceed +/-3K to allow for behavioural adjustments. Nikolopoulou [11] exposes the factors that affect adaptation and influence people’s actions to achieve it. According to her, the psychological dimension of adaptation involves a reaction which does not depend on the magnitude of a particular stimulus but on the amount of information a person has on it. This difference in thermal perception is attributed on the following factors: Naturalness, Expectation, Experience,Time of exposure and Perceived control. Merghani describes several field studies investigating on the behavioural adaptation patterns facilitated by environmental diversity. Fieldwork revealed the impact of environmental diversity in traditional houses on the temperature sensation and satisfaction of its users. Studies observed space-use patterns and behavioural adaptation strategies and revealed that movement from one space to another was largely motivated by the thermal profile of each

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room. People were always occupying the spaces that were within or closer to their comfort zone. This space would change during the course of the day. Potvin [12] conducted field research on environmental comfort in transient conditions. He states that transitions may be developed to produce a sense of continuity or contrast, by changing the degree of environmental stimuli like brightness, temperature, sound and air flow. This choice depends on whether the transition is happening towards or away from comfort, since adaptation is faster toward comfort and the change is more easily tolerated. For this reason he advises a subliminal adaptation (below the threshold of sensation) when moving from a more comfortable environment to a less comfortable one. Chun [13] conducted research on thermal comfort in transitional spaces. This was done through climate chamber experiments with people moving from one room to another, doing different activities. The objective was to determine how comfort and temperature perception is influenced by a person’s relative position in a sequence of temperatures as well as preceding and current activities. Results showed the same temperature was evaluated differently if the subject came from a cooler or from a warmer temperature room. This tendency was named “relative evaluation tendency” and was verified further in field studies. They further proved that users of transitional spaces, if walking with fast temperature changes, can adapt very widely their thermal sensations. This disproves the need for a narrow range of temperature conditions in transitional spaces.

the questionnaire were relevant, understandable and conclusive. The final experiments were conducted on 15-20 subjects, varying for each experiment. Every subject only took each experiment once, since surprise/expectation were crucial parameters to analyse and was asked to not discuss it afterwards so as not to compromise the results of the next subjects.

Figure 1: Typical experiment set representing one type of transitions between 3 temperatures.

3.2. Interpretation of results During the experiment, the subjects were asked to fill in a questionnaire assessing temperature estimation, pleasure scale and stimulation levels(overall results processed as in seen in fig. 2).

3. ANALYTIC WORK/EXPERIMENTS 3.1. Methodology &Description of experiments Following this theoretical review, a set of simple experiments was conducted in order to verify the very subjective and sometimes “romantic” theories and assumptions. The aim was to investigate different types of transitions, or sequences, starting from the most conventional ones and adding more “extreme” and pleasure related ones as theories have introduced, and the way they can trigger adaptive reactions and lead to comfort and delight. These extreme transitions also relate to the introduction of discomfort as a temporary step of the sequence and check the theory stating that this can have a pleasurable overall result. The main issues to investigate, and to confirm were type of transitions (subtle, gradual, contrasted, with cold or warm steps…), the impact of contrast (from imperceptible to shocking) as well as the influence of the other senses, like vision, by changes in light levels and colour. This would be achieved by passing the subject through different types of transitions materialised by passing one’s hand in buckets of water of different temperatures, representing in a simplified way (time and means not allowing otherwise) how the actual transition would take place (fig. 1). First, a pilot study (2 subjects) was conducted to confirm that the experiment types and

Figure 2: Graphs showing the combined results for one experiment, for each criteria separately and overall.

Finally a web diagram was created for each transition type which synthesized all the results, highlighted the high and low points of each and made all results comparable (as seen in fig. 3).

Figure 3: Web diagrams showing the results of one set of experiments. This allows for a clear view of each transition’s high and low points and makes comparisons easy.

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4. RESEARCH OUTCOMES/APPLICATIONS 4.1. General conclusions from the experiments Types of transitions and temperature sequences Gradual transitions prove most effective overall, • whether outside or within comfort boundaries. Contrasted transitions are less effective in • temperature perception but they are more stimulating. There is potential in voluntarily putting people in • uncomfortable conditions as a transitional step and still have a positive end result. When going back to comfort conditions (in the last step), these seem more pleasant by opposition than the same conditions reached gradually. This type of sequence proves also to be the most stimulating. Experiential differences between warm steps and cold steps In general warm steps are lowering stimulation • and cold steps increasing stimulation levels The same temperature difference in cold • temperature steps is generally more perceptible and less easy to tolerate than in warm steps. Perception and appreciation of contrasts Contrast increase leads to stimulation increase • Contrast is generally experienced very differently • whether the conditions are within comfort (warm contrasts in this case) or out of comfort (cold contrasts). In out of comfort conditions, contrast is generally unfavorably viewed. Within comfort conditions a certain level of • contrast can actually be beneficial. Too much contrast can be counter-effective. Temperature estimation is affected. The higher the contrast, the higher the pleasure • ratings. Impact of the speed of the visual change on temperature perception A fast visual transition, meaning a high light • change in a short time, has more potential to attract attention. Increasing the speed of light changes gives a more visual than thermal character to the transition. More gradual light changes are less noticeable. This also means that fast visual transitions are more effective in distracting from thermal changes than gradual and slow visual sequences which allow concentrating on the thermal. Gradual transitions in general prove more • effective in estimating the temperature closer to comfort. Fast visual transitions are characterised as more • pleasant than slow visual transitions. They are also generally more expectable. • •

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Parallel versus opposite transitions Parallel transitions are in general more expectable than opposite ones, especially for colour. No link/distinction was established between opposite/parallel transition and temperature estimation. In both cases, a gradual change will

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be more effective than an abrupt one (both in light and temperature). Thermal associations: Neutral versus coloured light In general people recognise the association • between colour and temperature (a warmer colour is associated with a warmer temperature). Coloured light is strongly associated with • temperature, much more than neutral. When temperature stays the same throughout the • sequences, a warming up in colour has the effect of a cooler estimation of that same temperature. 4.2. Practical applications/ implications for the design of transitional spaces The final part of this research was to put together all the results gathered from the experiments and give them practical applications. The objective here is to assess and categorise all the transition types that were tested and find out for which type of transitional space they have potential for. First of all, it is essential to define how these spatial or behavioural characteristics of a transitional space influence the environmental conditions necessary to provide comfort, as defined from the theories. The table below (table 1) links the above two. For example, a high metabolic rate in the transitional space will require conditions with low stimulation levels. Stimulation can have the effect of increasing metabolic rate further and should thus be avoided. The same reasoning applies to all other conditions.

Table 1: Behavioural characteristics linked to the environmental conditions necessary to provide comfort.

 

The next table (table 2) shows a typical set of transition types tested and summarises its comfort/pleasure assessment. According to this, and the first table, these features match a few programmatical requirements and thus make each transition potentially more appropriate for a specific type of occupant conditions.

 

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comfort.

   

Finally, the last table (table 3) shows, inversely, the requirements of a certain number of transitional spaces[14], leading to the most appropriate type of thermal and environmental sequencing for them, to effectively provide comfort and delight. Transitional spaces are categorised into outdoor or indoor dominant, to determine how much indoor comfort criteria apply. The occupant related criteria, mostly based on behavioural and psychological criteria (referring to Nicolopoulou[15]) determine the type of sequencing that will be most suitable.

 

For example, a hotel lobby would benefit from highly contrasted warm transitions, with either warm or cold steps. Cold transitions can accept any contrast as long as a warm step (over comfort) is involved. The visual sequencing should follow coloured light changes in general, preferably fast. For every type of transitional space, the same methodology applies to find its most suitable transition type/thermal sequencing.

 

Table 2: Typical set of transitions tested and their comfort assessment, leading to a programmatical potential.

For example, a gradual transition in warm conditions, by leading people to perceive temperatures cooler than they are, has the potential to accept activities with a high metabolic rate and/or clo value. The perception of it as subliminal makes it appropriate for conditions relatively outside of

This grid can provide a sort of guideline for design, which can be interpreted in countless ways.

     

Table 3: Table showing a certain number of transitional spaces and their most appropriate transition type to lead people into comfort.

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For example, in the last case of the hotel lobby, a warm transition with a warm step might be interpreted as an atrium left to slightly overheat in the summer. This would mean that the user would enter the transitional space/lobby from the warm outside, to find even warmer conditions. This will influence him to feel much more comfortable by contrast when reaching his “comfortable” hotel room than if the same conditions had been reached gradually. This in its turn can lead to energy savings since the hotel lobby will have much less cooling needs. It is even conceivable that the hotel room itself will have less cooling needs because this temperature contrast might make the user tolerant to slightly warmer conditions as well.

5. CONCLUSION This study explained and developed the processes of thermal adaptation and the need for variability. Transitional spaces, as the main source of this diversity, were then investigated to determine how and to what extent different types of environmental sequencing can influence the perception users have of the conditions. The experiments conducted procured interesting results, mainly related to the impact that different types of sequences can have in the perception of temperature, to the experience and the appreciation of contrasts as well as to the influence the visual world can have on thermal sensation. These findings generally concurred with the related literature and the existing theories. Different transition types were assessed and categorised, their high and low points highlighted, to determine for which type of transitional space they have potential for. Subsequently, the requirements (space and occupant behaviour related) of a certain number of transitional spaces was established to make correlations between these and the above mentioned transition type potential. The final outcome was to assign the most appropriate transition type to each transitional space, so as to provide most effectively comfort and pleasure. The current investigation, because of limited means, time and experiment samples and subjects, does not have the scale to produce incontestable conclusions. However, the end result, after a more profound research following the same methodology, could give birth to a valuable guideline for the architectural and environmental design of transitional spaces.

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6. REFERENCES [1] Hawkes,D(2007), The Environmental Imagination. Routledge, p203 [2] Auliciems A. & Szokolay S.V. (1997), Thermal Comfort, PLEA note 3 [3] Heschong, L. (1979). Thermal Delight in Architecture. MIT Press Bell (2001), p76 [4] Bell, P.A. et al (2001). Environmental Psychology. Fifth Edition. Hartcourt College Publishers [5] Auliciems(1997), p16 [6] Mudri, L. and J.D. Lenard (2000). Comfortable and/or pleasant ambience: conflicting issues. PLEA 2000 Conference in Cambridge, UK, , p 599 [7] Kwok, Alison G. (2000). Thermal Boredom. PLEA July 2000, Cambridge, England. [8] Exploring thermal comfort and spatial diversity, in Steemers, K., M.A. Steane (Eds. 2004). Environmental Diversity in Architecture. Spon Press, pp195-212 [9] Knudsen H.N. & Fanger P.O. (1990). The impact of temperature step-changes on thermal comfort. Indoor Air 90, p757-61 [10] From Pagliano L., Sustainable Summer Comfort: Comfort Model. Austrian Energy Agency, Vienna [11] In Steemers & Steane (Eds 2004), pp101-120 [12] Potvin A. (2000). Assessing the microclimate of urban transitional spaces. PLEA 2000 Conference in Cambridge, UK, , p 581 & Potvin A., A.L. L’Heureux, B. Saricoglu, K. Zarnovican.(2002) Assessing environmental comfort Proceedings of the PLEA 2002 Conference in Toulouse [13] Chun, C., Kwok, C., Tamura, A., (2004) Thermal comfort in transitional spaces – basic concepts: literature review and trial measurement. Building and environment, vol.39, issue 10, p1187-1192 & Chun, C., Tamura, A., (2005) Thermal comfort in urban transitional spaces. Building and environment, vol.40, p633-639 [14] Chosen from Chun (2004) [15] In Steemers & Steane (Eds 2004), pp101-120

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Financial Motivation to Improve Thermal Comfort and Reduce Carbon in Office Buildings Joshua KATES1 1

Built Ecology, London, United Kingdom

ABSTRACT: The link between thermally comfortable office environments and occupant satisfaction (measured by improved productivity, reduced staff leave and reduced staff turnover) is well understood. Traditionally, refurbishment financial models take into account capital cost, operational energy and maintenance costs but do not account for increases in occupant satisfaction. This methodology masks a key input to effective decision making as staff wages are one of the largest costs to a company. This paper demonstrates that retrofitting existing office buildings to improve thermal comfort will provide a positive Net Present Value (NPV) proposition to building occupiers while simultaneously reducing energy and carbon. Thermal comfort modelling was used to test four passive design initiatives: increased insulation, performance glazing, external shading and thermal mass optimisation. By using Predicted Mean Vote (PMV) as an indicator for increased occupant satisfaction, this paper presents a holistic financial model of four key passive design options. Keywords: comfort, carbon, productivity, passive design

1. INTRODUCTION This paper has been written to help associate a hard dollar value against the so called soft benefits of adopting passive design alternatives – specifically, productivity benefits associated with improved thermal comfort. Traditionally, refurbishment financial models take into account capital cost, operational energy and maintenance costs but do not account for increases in occupant satisfaction. This methodology masks a key input to effective decision making as staff wages are one of the largest costs to a company. Six variables are used to address thermal comfort holistically: air temperature, radiant temperature, humidity, air speed, clothing and activity rate. Standard HVAC equipment only controls air temperatures and sometimes humidity. Passive design measures can be used to effectively control radiant temperatures in the space by reducing solar gain and stabilising radiant temperatures throughout the day. Radiant temperatures account for around 40% of perceived temperature in a space and are therefore an important aspect in maintaining thermally comfortable environments and creating productive work environments. This paper analyses the Net Present Value and the carbon intensity of a traditional 1960s office building and the affect of four different passive design refurbishment options: increased insulation, performance glazing, external shading and exposing the thermal mass. This paper provides analysis through the following steps:  Determining an appropriate average cost to associate with the employment of an average office worker.

  

Reviewing the costs and causes of productivity as it relates to thermal comfort. Determine the appropriate passive design alternatives and their related costs Determine the Net Present Value and energy intensity of each passive design option

1.1. Modelling software Thermal Analysis Software (TAS) was used in order to estimate the thermal comfort and carbon intensity of the various options in this study. TAS uses fully dynamic calculations to provide an accurate insight into the building envelope response as well as space and surface temperatures, internal loads and energy consumption. A Test Reference Year (TRY) weather file based on historical records of radiation, temperature, humidity, sunshine, wind speed and direction for every hour of the year was used.

2. THERMAL COMFORT 2.1. Designing for Thermal Comfort The thermal comfort of a building is defined in the International Standard ISO 7730:2005 [1]. Thermal comfort is primarily made up of six contributing factors:  Air temperature  Radiant temperature  Humidity  Air velocity  Clothing levels  Activity rate Thermal comfort is a measure of how comfortable the indoor environment is perceived to be by its occupants. Thermal comfort modelling is used to give an indication as to the proportion of occupants who notice warmth or coolness in a space. As the

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proportion of occupants noticing a certain thermal environment increases, the level of thermal comfort deteriorates. Where this proportion of “dissatisfied” occupants is low, the level of thermal comfort is considered to be good. The international standard (ISO 7730:2005) has been created for determining thermal comfort. PMV is the benchmark for the International Standard. Conditions under different PMV levels are described in Table 1 below. Table 1: Seven-point thermal sensation scale [1]

Predicted Mean Vote (PMV) +3 +2 +1 0 -1 -2 -3

Internal Conditions Hot Warm Slightly warm Neutral Slightly cool Cool Cold

Predicted Mean Vote is based on a mathematically generated response, based on empirical data of what each person in the space would “vote” if asked for their opinion on the state of the indoor environment, with each person selecting one of the options in the table above. The PMV is the mean result from all those “votes”. Most air-conditioning systems will be able to maintain PMV levels within ±1 for most of the space most of the time. Air-conditioning systems which address radiant temperatures (such as chilled ceilings) can improve this and usually maintain thermal comfort conditions within ±0.5. However, in a typical office building with a VAV system, air temperature and sometimes humidity are the only factors that are adequately addressed by the HVAC design. Radiant temperature (primarily driven by the temperature of the ceiling and the floor) is not controlled, and air velocity can be erratic and cause discomfort, with many occupants complaining about draught. Radiant temperatures are particularly important as they account for around 40% of the means through which we perceive what the temperature is but are often not controlled. Passive measures of increased insulation, improved glazing, exposing thermal mass and external shading can be used to effectively control radiant temperatures.

3. LEAVE, TURNOVER AND PRODUCTIVITY 3.1. Cost of employing staff The average cost of employing a member of staff can be calculated by taking into account the following different sources: salary, superannuation, additional employee on-costs and overheads. Taking into account these costs the average cost of employing each staff member in Sydney, Australia is assumed to be AUD$65,872 which is AUD$4,391 2 2 per m at an average density of 1 person per 15 m .

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Costs are based on the following information:  The Australian Bureau of Statistics reported the average salary for full time NSW workers in 2004 was AUD$49,818 [2].  Superannuation is also paid by the employer in NSW, at a minimum rate of 9% [3]. This increases the effective average salary package cost to the employer to AUD$54,294.  Payroll Tax, Long Service Leave, Sick Leave provisions and Worker‟s Compensation are taken as being an additional 5.5% of the total salary package cost [4] which increases the effective average salary package cost to the employer to AUD$57,280.  Overheads including the cost of rent, office facilities including computer equipment, support staff, utilities and fringe benefits account for a further 15% of the total salary package [5] increasing the effective average salary to the employer to AUD$65,872. Table 2 breaks down these costs to the employer. Table 2: Breakdown of cost of employing staff

Average salary Superannuation On-costs Overheads Total cost of employment per employee Total cost of 2 employment per m NLA

AUD$49,818 AUD$4,483 AUD$2,986 AUD$8,592 AUD$65,872 AUD$4,391

3.2. Staff productivity A number of assumptions about productivity must first be established before estimating costs and benefits of improved productivity. This paper assumes that there is no theoretical cap to the potential for improving productivity when considering marginal improvements. Additionally, this paper assumes that an improvement in productivity affects all tasks linearly and proportionately. This paper uses the annual expenditure on staff 2 per m as the benchmark for measuring productivity. This means that for each 1% improvement in productivity, the average business will produce an additional AUD$43.91/m2/year in revenue. In reality, revenue generated by staff in a successful business is significantly higher than their cost to the business, but this approach allows for an extra level of conservatism in calculations of benefits. 3.3. Absenteeism, separation

sick

leave and

voluntary

The reasons for absenteeism, sick leave and voluntary separation are varied and poorly documented, both by the private and public sectors. Generally, reasons for unapproved leave can be divided into sections: illness contracted in the office; illness contracted outside the office; work related

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stress; non-work related stress; lack of motivation and other factors. Of these various factors, only illness contracted inside and outside the office environment will be exacerbated by poor thermal comfort in the work place. Voluntary separation or churn creates costs associated with finding, interviewing and training new employees. The reasons for staff turnover are only partly due to unhealthy or poor physical working environments. As with sick leave, the reasons for staff turnover are complex and varied. Some of the reasons for voluntary separation are: retirement; external opportunities; staff conflict; dissatisfaction; displacement by partner and family moving location and finally dissatisfaction with the workplace. While improved thermal comfort could potentially reduce the amount of absenteeism, sick leave and voluntary separation, these factors have been omitted from this study based on lack of adequate information to assess the costs.

4. SELECTION OF COMPARISON

OPTIONS

FOR

A standard 1960s office base option design in Sydney, Australia will be considered by this study. Four commercial refurbishment options have been selected based on feasibility, predicted thermal comfort benefit and energy/carbon reduction. 4.1. Base option – Standard Office 1960s build The base option for this study is derived from the typical approach to designing commercial office buildings in Australia. This approach is based on the use of Australian Standards as design guides and is characterised as follows:  8am to 6pm occupied office hours (Monday to Friday)  Lighting Gain – 12W/m2  Equipment Gain – 7 W/m2  Occupant Gain – 1 person/15m2  Infiltration – 0.5 air changes per hour in perimeter zones  A central air-handling and conditioning plant supplying cold air to office spaces, with variations in the quantity of air supplied used to control the overall temperature. Figure 1 below depicts a visual representation of the base option office building from the Thermal Analysis Software where the following dimensions have been modelled to represent a typical office block:  50m X 50m square dimensions with a 25% central core and facilities area  3m floor to ceilings with full width glazing and 1m sill height and 10% aluminium window framing

Figure 1: Visual representation of base option office building

4.2. Option 1 - Base option with increased insulation The passive design refurbishment for Option 1 is the injection of bead insulation into the wall cavity. The purpose of this insulation is to decrease the amount heat conduction into the space and also to decrease the energy required for the HVAC system.  Base option whole wall thermal conductivity equal to R0.80. Option 1 whole wall thermal conductivity equal to R0.36. 4.3. Option 2 - Base option with performance glazing The passive design refurbishment for Option 2 is the replacement of the glazing with performance glazing. The purpose of installing performance glazing is to reduce the amount of solar gain into the space lowering radiant temperatures and reducing the load on the HVAC system.  Base option double glazing Solar Heat Gain Coefficient (G-value) equal to 0.68. Option 2 performance glazing Solar Heat Gain Coefficient equal to 0.35. 4.4. Option 3 - Base option with external shading The passive design refurbishment for Option 3 is the introduction of external shading. The purpose of external shading is to reduce the amount of solar gain into the space lowering radiant temperatures and reducing the load on the HVAC system.  The base option has no external shading. Option 3 has assumed a 1:1 shading ratio for refurbishment (i.e. 2m horizontal shading for 2m high glazing). 4.5. Option 4 - Base option with exposed thermal mass The passive design refurbishment for Option 4 is exposing the thermal mass. The purpose of exposing thermal mass is to stabilise radiant temperatures in the space over the day improving comfort conditions and reducing the load on the HVAC system.  Base option ceiling to floor construction is ceiling tiles, air gap, concrete, and carpet. Refurbishment option 4 removes the carpet and the ceiling tiles thus exposing the thermal mass on both the floor and ceiling.

5. QUANTIFYING IMPROVED ENVIRONMENT QUALITY

INDOOR

5.1. Staff Productivity Predicted Mean Vote has been related to staff productivity in several studies in terms of different

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100.0% 95.0% 90.0% 85.0% 80.0% 75.0% 70.0%

Base Option

Option 1 Added Insulation

Option 2 Performance Glazing

Option 3 External Shading

Option 4 Exposed Thermal Mass

Figure 3: Annual productivity results based on modelled thermal comfort

For typing tasks: 6

5

4

3

3

2

y = -60.543x + 198.41x – 183.75x – 8.1178x + 2 (1) 50.24x + 32.123x + 4.8988 For thinking tasks: 5

the modelled options where 100% represents a „perfect‟ productivity. Annual productivity (%)

combination of thermal criteria (air velocity, clothing, etc.) and the type of task undertaken (thinking or typing). Kosonen and Tan in [6] derive Equations (1) and (2) below for typing and thinking tasks in regard to productivity loss. The equations were derived parametrically by making use of three relevant studies whereby real life tests were carried out to determine how various climatic conditions impacted thinking and typing tasks. These experiments were then reconstructed into PMV results and expanded to understand how thermal comfort impacts productivity across the full PMV spectrum.

4

y = 1.5928x – 1.5526x – 10.401x + 19.226x + 13.389x + 1.8763 (2) where y = Productivity Loss and x = PMV Index These two equations can be used to derive various PMV vs Productivity Loss curves for various permutations of thinking and typing tasks.

Figure 3 shows that none of the options has an100% annual productivity. For this to occur, the PMV would have to equal -0.21 for each of the 12 zones for every occupied hour. These data demonstrate that the introduction of insulation decreases the annual productivity by 0.8%. The explanation for this is that increased thermal insulation prevents heat escaping overnight therefore increasing radiant temperatures for the following morning. The installation of performance glazing and external shading improves the productivity by 9.9% and 9.0% respectively. These two options are the most effective methods of those modelled to control the radiant temperatures in the space and optimise the Predicted Mean Vote values in the space to improve productivity. Exposing thermal mass has a 1.0% positive effect on annual productivity.

6. ECONOMIC ANALYSIS

Figure 2: Various thinking and typing permutations of productivity loss vs PMV curves [6]

This section integrates the cost benefits obtained from alternative passive design measures with the capital costs of each option. The intent of this section is to demonstrate the cost implications of the various passive design measures when incorporating the productivity of the staff. 6.1. Capital costs of passive design measures

As this paper seeks to model an average office building the basis of calculations will be to use the 50% thinking and 50% typing curve for all the productivity calculations. 5.2. Productivity Results Thermal Analysis Software (TAS) was used to dynamically model the base option and four passive design refurbishment options to obtain Predicted Mean Vote results averaged over 12 separate zones for each hour of the year. Each PMV result was then matched to the corresponding level of productivity loss as described by the productivity loss equations as represented in Figure 2. These productivity losses were then summed over the year to create a single percentage annual productivity of the staff across the floor area. Figure 3 presents the final productivity results for each of

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COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

Table 3 presents the capital cost of each of the passive design options. Each of the options has been assumed to have no maintenance costs associated with their implementation, which is one of the major benefits of passive design. Table 3: Capital cost refurbishment options

Passive design refurbishment Injection of bead insulation into wall cavity Performance glazing External shading Exposing thermal mass

of

various

passive

design

Capital Cost 2

AUD$15/m of wall 2

AUD$1,000/m of glazing 2

AUD$500/m of shading 2

AUD$100/m of floor

6.2. Cost savings Each of the passive design options not only impacts the thermal comfort but also the cooling load in the space. Figure 4 presents the results for the change in cooling load relative to the base option. 100% 80%

$400 $300 $200 $100 $-$100 Base Option

40%

Option 1 - Option 2 - Option 3 Added Performance External Insulation Glazing Shading

Option 4 Exposed Thermal Mass

Figure 6: Productivity gain in AUD$ per m2 for each passive design option

20% 0% Base Option

Option 1 Added Insulation

Option 2 Performance Glazing

Option 3 Option 4 External Exposed Shading Thermal Mass

Figure 4: Percentage change in cooling load for each passive design option

As with productivity, the addition of insulation prevents heat escaping overnight therefore increasing the cooling load for the following morning. However, the installation of performance glazing, external shading and exposing the thermal mass all decrease the cooling load by 44%, 42% and 3% respectively. Figure 5 shows the cooling load change in terms of annual cost based on an average electrical tariff of AUD$0.10/kWh. The cooling load reduction is directly related to the carbon intensity of the office space. That is, as the cooling load decreases so does the carbon intensity. 9.00

Cooling load cost ($/m2/year)

$500

60%

8.00 7.00 6.00 5.00 4.00

3.00 2.00 1.00 0.00 Base Option

Option 1 Added Insulation

Option 2 Performance Glazing

Option 3 External Shading

Option 4 Exposed Thermal Mass

2

Figure 5: Cost of cooling per m per year for each passive design option

6.3. Staff productivity results Figure 6 presents the results for the staff productivity gains for each of the passive design refurbishment options on a meter squared per year basis. The productivity gains are based on potential additional revenue created from the increased productivity as calculated and shown in Figure 4 and additional revenue as described in Section 3.2.

These results can be compared with those of cooling load reduction in Figure 5 to see that productivity gain is larger nearly by a factor of 100. This highlights the holistic importance of taking into account staff productivity. 6.4. Net Present Value The Net Present Value (NPV) is a financial model that takes into account capital costs as well as all future cash flows either positive or negative throughout a particular timeframe. The timeframe chosen for this NPV analysis is 10 years. Figure 7 presents the Net Present Value proposition to an employer of each passive design option and demonstrates the large benefit when looking at performance glazing and external shading in particular. Taking the best performing option of performance glazing, these figures indicate that a Net Present Value of approximately AUD$5,000,000 can be earned by this refurbishment option taking into account energy saving and increased productivity of staff through better thermal environment. Net Present Value per m2 (AUD$)

Change in cooling load (%)

120%

Productivity gain based on PMV and cost of staff ($/m2/year)

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

$3,000

$2,500 $2,000 $1,500 $1,000 $500 $0 -$500 Base Option

Option 1 Added Insulation

Option 2 Performance Glazing

Option 3 Option 4 External Exposed Shading Thermal Mass

Figure 7: Net Present Value per m2 for each passive design option

7. CASE STUDY Council House 2 (CH2) as pictured in Figure 8 is the City of Melbourne‟s new office building in Australia. When upgrading from their previous building, CH1, the client was very keen to design and build an innovative building that included both passive and active design measures. Some of the initiatives included performance glazing, external shading, exposed thermal mass and above compliance insulation in combination with night purge.

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

9. LIMITATIONS AND FURTHER STUDIES

Figure 8: Picture of CH2 from front showing external shading (left) and inside showing exposed thermal mass (right)

Extensive third party studies were carried out on CH2 to determine the occupant productivity pre- and post-occupancy in the form of surveys, indoor environment quality monitoring, indoor air quality monitoring and focus group interviews of occupants. While impossible to separate which design initiatives accounted for which gain in productivity, the conclusions can be summarised as a 10% increase in productivity [7] as shown in Figure 9 below. 6.0%

Productivity Loss/Gain

4.0%

2.0% 0.0% CH1

CH2

-2.0%

-4.0% -6.0% -8.0%

Figure 9: Perceived productivity from CH1 to CH2 [7]

8. DISCUSSION AND CONCLUSION Acknowledging that thermal comfort increases the productivity of a building‟s occupant unmasks a key driver in understanding the financial motivation for undertaking passive design retrofit options. Examining the case study performance as well as the performance glazing and external shading initiatives modelled demonstrates the powerful incentives that exist to include productivity as a metric for effective decision making in refurbishment projects. The decrease in energy usage per year is 2 approximately AUD$5/m /year whereas the increase in revenue from these initiatives is approximately 2 AUD$450/m /year (i.e. the cooling load savings account for around 1% of the financial motivation when considering passive design refurbishment options). This paper has laid out a methodology that can be applied to an actual building to more holistically assess various refurbishment options within a sites context.

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COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

There are a number of limitations to this paper and a number of further studies to generate more accurate results. This study has not considered the potential negative productivity benefits due to reduced daylight through the use of performance glazing or external shading. This must always be considered in actual building design. This study has used the Sydney climate which is a cooling based climate. The results and passive design options selected are highly dependent on whether the climate is heating or cooling based and would require adjustment accordingly.

10. ACKNOWLEDGEMENTS I would like to take this opportunity to thank WSP, in particular Matthew Payne of Built Ecology, a specialist environmental division of WSP for his support in giving me the time and inspiration required to write this paper. I would also like to thank Andrew Corney of Built Ecology for providing some of the fundamental ideas behind this paper. Particular thanks to Beatrice Hon for her valuable guidance and support, as always.

11. REFERENCES [1] BRITISH STANDARDS INSTITUTE (2005) BS EN ISO 7730:2005: Ergonomics of the thermal environment – Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria. United Kingdom: British Standards Institute. [2] AUSTRALIAN BUREAU OF STATISTICS (2009) Employee Earnings and Hours, Australia, Aug 2008 [WWW]. Available from: http://www.abs.gov.au/ausstats/[email protected]/mf/63 06.0/ [Accessed 15/11/2010]. [3] AUSTRALIAN TAX OFFICE (2010) Compulsory employer contributions [WWW]. Available from: http://ato.gov.au/individuals/content.asp?doc=/c ontent/00250233.htm&page=3&H3 [Accessed 15/11/2010]. [4] NSW GOVERNMENT (2010) Payroll tax [WWW] Office of State Revenue. Available from: http://www.osr.nsw.gov.au/taxes/payroll/ [Accessed 15/11/2010]. [5] DG & AB MAXWELL CONSULTING ACCOUNTANTS (2004) Corporate overheads of local governments. NSW: DG & AB Maxwell Consulting Accountants, pp. 1-15. [6] Kosonen, R. and Tan, F. (2004) Assessment of productivity loss in air-conditioned buildings using PMV index. Energy and Buildings, 36 (10), pp. 987-993. [7] CSIRO (2008) Indoor Environment Quality and Occupant Productivity in CH2 Building: Post Occupant Summary. Melbourne: CSIRO, pp. 138.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

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                                                                                                                                                  

                                                                                                                                                                       

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                                                                                                               

                          

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COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                                                                                                                                                                                                                                                                                                                        

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 



494

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.



                                                                                                                                                                                                                                                                                              

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                                                                                                                                              

                                                                                                                                                                                                                                

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COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

495

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

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                                                                                                                                                                                                                                                                                                                                                                                                 



 

 

 

 

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496

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                                                                                                                                                                                                                                                                                                                                                                                                           

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                                                                                        



                                                                                                                                                                                                                

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COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

497

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                                                







                                                         

 

                                                                                                                                                                                                                  

498

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

                                                                                                                                                                                                    

                                                                                                                        

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

                                                                            

                                                                                                                                                     

                          

                 



                                                                     

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

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

                                                             

 

                                                                                                  

500

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)



                                                                                               



  

  

  

  





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





























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





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





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                                                                             

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

 

 



 



 

 

  



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









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





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                        

                                                               

           

    

  

      

  

     

                                       

                                                                                                                                                      



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     

                                              

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

501

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

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                                                     

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                                  

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                  

                                                                          

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                                                                      



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COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

 

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                                                                                                                                                                                                                          

                                                                                                                                                                                                      

                                                                                                                               

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. th

                                                                                                                   

                                              

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COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

                                                                                                        

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Importance of occupant’s adaptive behaviour behaviour for sustainable thermal comfort in apartments in India MADHAVI INDRAGANTI 1 1

College of Art and Design, Princess Nora Bint Abdul Rahman University, Riyad, Saudi Arabia

ABSTRACT: Thermal comfort is essential for user satisfaction in a building and poor indoor comfort often forces the user to take high energy intensive solutions to restore comfort. India’s energy consumption in residential consu sector is increasing phenomenally. There are no thermal comfort standards in India or recent research reported in this field. Indian comfort standards are based on ASH ASHRAE Standard-55, 55, which do not take many local factors like adaptation of occupants into consideration. Here we show that various thermal adaptation methods followed by the occupants were vital for indoor thermal comfort in apartments. We found the comfort comfor temperature obtained through the field study in apartments to be way above the one specified in the codes. Fanger’s Predicted Mean Vote (PMV) used by practitioners was always higher than the actual thermal sensation recorded in the field study. Furthermore, re, we found occupants displaying ‘thermal empathy’ adapting better. These findings critically question the application of the current temperature standards and the PMV for the design of the thermal environments in India, with far reaching energy implications implications in a developing country like India. Our results demonstrate the importance of adaptation and how adaptation was impeded by many factors. Keywords: Adaptive thermal comfort, Field study in Apartments, Comfort temperature, Comfort standards

1. INTRODUCTION Raison d'être of building design effort is providing thermal comfort to the occupant. occupant Thermal comfort is essential for user satisfaction and health while the desired indoor temperature usually decides the energy bill. The indoor environment in naturally ventilated (NV) buildings greatly depends on the local climate and the way environmental controls are re used. The harshness of the effect of outdoor climate can be modified by the use of controls. Users can modify the thermal environment using common controls like operable windows and w fans. Thermal comfort research in India is extremely limited [1] with no thermal comfort standards in Indian Codes. Energy consumption in Indian residential buildings is increasing phenomenally and is highest among the Asia Pacific Partnership countries [2]. ]. About 73% of the energy consumed in Indian residential buildings is used for lighting (28%) and ventilation controls (fans - 34%; Air coolers 7%; A/c - 7%) to provide thermal and visual comfort indoors [3]. For a populous nation like India, the ramifications of this high energy use are serious. While environmental controls are important in reducing the need for high energy solutions, the perceived usefulness of a particular control will change from time to time depending on conditions [4]. ]. Behavioural use of controls links the physiology/ psychology of the body and the physics of the building [5]. ]. It is thus, a major link in the dynamic interaction between buildings and their occupants. The use of controls ls is never an isolated action, but is part of a feedback loop and is the result of occupants’ very complex behaviour. These feedback mechanisms embodied in the adaptive principle create an order in the relationship in between outdoor climate and comfort temperature temp

a NV building [4]. ]. On the other hand, this order is broken in a HVAC building as outdoor climate is decoupled with the indoor environment. Assumable, the nature of use of controls and the triggers for the is quite use of controls in residential environments environme different from that of the office environments.

Figure 1: The instruments, instrument set-up for field set survey and the survey environments

There is little research done in understanding the adaptive use of environmental controls in India. To fill this gap, the author conducted a field study in Hyderabad in India in summer and monsoon in 2008. The present paper analyses the way various controls were used and highlights the importance of occupant’s adaptive behaviour for sustainable in India. indoor thermal comfort in apartments apart

2. METHODS Hyderabad (N17°27’ and E78° 28’ and 540 m above the mean sea level) has composite climate with four distinct seasons: summer, monsoon, post

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. monsoon and winter. It is the capital city of the state of Andhra Pradesh in India. 2.1 Field Survey A field study was conducted in summer (May) and monsoon seasons (June and July) having great discomfort. It was done in 45 flats of five apartment buildings. A total of 33 days were spent in surveys involving over 113 occupants and a total of 3962 data sets were collected. All the surveys were conducted by the author herself. 2.2 Outdoor and Indoor Environmental Data Collection Daily maximum and minimum temperature and humidity for all the days of the survey was collected from the local meteorological station. Mean minimum outdoor temperatures during summer and monsoon sample periods were 27.3 °C and 24.1 °C, respectively. Mean maximum outdoor temperatures of the summer and monsoon sample periods were 40.4°C and 34.2 °C, respectively. Over the summer study period, the mean 8:30 hrs and 17:30 hrs relative humidity (RH) were 38.6 % and 26.7 %, respectively. The relative humidity in the monsoon period was relatively higher. The mean 8:30 hrs and 17:30 hrs relative humidity (RH) were 66.1 % and 46.7 %, respectively. All the four environmental variables: air and globe temperature, air velocity, and relative humidity were measured using calibrated digital instruments following ASHRAE’s Class – II protocols for field study [6].The surveys were conducted in two levels: one day of transverse survey followed by four days of longitudinal survey in all the months of the survey in all the flats. Every subject was interviewed thrice daily to collect morning, afternoon and evening comfort votes, while simultaneous environmental measurements were made. The survey was conducted in living/dining rooms of the surveyed apartments as shown in Fig.1.Details of survey questionnaires and data collection are presented in Indraganti [7]. Subject’s metabolic rate and clothing insulation were estimated based on standard checklists [6]. ASHRAE’s seven point scale of thermal sensation (3-Warm; 0-Neutral; -3-Cold), ASHRAE’s nominal scale of acceptance (2-Acceptable; 1Unacceptable), Nicol’s five point scale of preference (2-Much cooler; 0-No change; -2-Much warmer) and four point scale of skin moisture (3-Profuse; 2Moderate; 1-Slightly; 0-None) were used in this study [6]. In addition, the transverse questionnaire had questions on sensation and preferences for other environmental parameters, behavioural and structural adaptations and tenure. 2.3 Sample Size and Description Five naturally ventilated mid rise apartment buildings named KD, SA, RA, KA and RS were surveyed. These were five to thirty year old 3-6 storied buildings, located in the residential areas of central and eastern parts of Hyderabad city. These buildings have plastered brick (115 – 230 mm thick), / hollow cement block walls (150 mm thick), in RCC frame work, a typical construction used locally. They have a RCC flat roof of 150 -200 mm with a weather

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proof coat of brick jelly concrete (75- 150 mm) on the top. A few top floor flats in KD, SA and RA were finished with a false ceiling, whereas one flat in KD had its roof painted in white reflective paint. The architectural details of these buildings are presented in Indraganti [8]. About 35 male subjects (~ 35%) and about 64 female subjects (~65%) voluntarily participated in the surveys. They were in the age group of 17- 69 years with male and female average age of 40.14 years (SD= ~14.0) and 42 years respectively. They were all acclimatised healthy Indian nationals living in the surveyed flats for over 3 months. The sample size varied slightly in each month, as some subjects have refused to participate in the surveys. One of the objectives of the research was to investigate into the thermal comfort perceptions of the occupants in the top-floor flats. Hence, 29-48% of the sample was also taken from the roof exposed (RE) top-floor flats in all the buildings. Results and Discussion 2.1. Subjective Thermal Responses Indoor temperature in summer was very high (much higher than the skin temperature of 32-34 °C) with very low humidity. Moreover, the thermal conditions in May were found to be harsh with inadequate adaptive opportunities available to the occupants in flats. This resulted in a majority (60%) voting outside the three central categories of the sensation scale, expressing discomfort. They (93%) also preferred a temperature on the cooler side of the neutrality, despite accepting their thermal environments (69%) in May, (mean TS = 1.8; mean TP = 1.3). 2.2. The Adaptive Comfort

Model

of

Thermal

The adaptive thermal comfort model is a linear regression model based on field studies. It therefore integrates various environmental, behavioural and psychological adaptations and thus forms the basis for sustainable thermal comfort standards.

Figure 2: Relationship between actual thermal sensation and Fanger’s Predicted Mean Vote (PMV) with indoor globe temperature (all data, n= 3962). Fanger’s PMV always over estimated the thermal sensation.

In this study, thermal sensation vote was regressed against indoor globe temperature, which yielded the relation, TS = 0.31Tg - 9.06, with a moderate coefficient of correlation of 0.65. A neutraltemperature of 29.2 °C and a comfort range (voting within -1 to +1) of 26.0 °C and 32.5 °C was thus obtained (Fig. 2).

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. This range is much higher than the comfort range of 23 – 26 °C, specified in the Indian Codes [3, 9]. It was noted that, very little or no discomfort was experienced by 80% of the subjects, when the mean indoor temperature was between 28.7 and 32.5°C. Fanger’s predicted mean vote (PMV) does not take into account the adaptation and acclimatization of the occupants, PMV was higher and had a higher correlation with globe temperature (Tg), (r = 0.93, all data), similar to Raja and Nicol [10]( Fig.2).

3. OCCUPANT ADAPTATION THERMAL COMFORT

FOR

3.1. Clothing and metabolism The occupants adapted through clothing and metabolism to maintain comfort. Clothing insulation varied from 0.19 – 0.84 clo in this study, while metabolism varied from 0.7 – 2.0 Met (sleeping – standing working). Understandably, subjects chose lighter clothing (0.15- 0.3 clo) and took post- meal siestas during the hot mid-day in summer. Some men adapted by wearing a lungi (a 2 m X

Saree

Saree

Lungi

Lungi

Figure 3: Clothing adaptation in women and men using traditional ensembles. Women/men draped the sari/ lungi in different ways to suit to the activity, changing the micoclimate around the body.

1.4 m long cloth draped around the waist), and left the torso bare, during the hot period. Some female subjects wore lighter clothing during heavy kitchen work. When these adaptations were restricted, due to some temporal and other socio-cultural reasons, they expressed discomfort and gave a high sensation vote. Older women (age >40yrs) for example, were usually dressed in saris (clo =

0.55~0.66), a culturally more acceptable costume, even when other lighter clothing options were available (long gown = 0.29 clo). However, the sari/ lungi offered women/ men, much better choice in terms of draping, to change the micro climate around the body suitably (Fig 3). 3.2. Adaptation through controls in the room

environmental

Windows, doors and curtains Indoor comfort in naturally ventilated environments strongly hinges on the use of environmental controls like doors, windows, curtains, fans, coolers etc., and the same was noted down in all the surveys as binary data (0closed/ not in use; 1- open/ in use). It was observed that the occupants used (opened/closed) these controls rather adaptively as the discomfort increased and the indoor/outdoor temperature increased. Similar observation was made by Raja and Nicol [10]. They were found to be in maximum use at around the upper limit of comfort zone, coinciding with thermal comfort vote of +1. (Fig.4). It was noted that the effect of air movement was most significant for comfort when the subject is at the upper limit of comfort temperature. Contrastingly, at high temperatures, encountered in Hyderabad in arid summer season, excessive natural ventilation caused convective and conductive heat gain and caused radiant heat discomfort as well. This led to the adaptive closure of most windows/ doors and curtains (Fig. 4). A discussion on the use of windows in greater detail is presented in Indraganti [11].

Impediments in using the controls The importance of the adaptive use of environmental controls is well established in achieving thermal comfort in NV apartments. Although all the apartments are provided with the above mentioned controls there were some impediments found in using them. Most important impediments were found to be privacy and security aspects related to the use of controls. More importantly, the realm (public/ private) into which the window/ door opened critically hindered the control operation behaviour of the occupant. In all the cases where windows / doors opened into the public realm (ex: corridors etc) higher indoor temperature

Figure 4: Changes in proportion of use of different controls in use with outdoor temperature and thermal sensation (All data, all months - binned) (POW/ POB/ POC = Proportion of open windows/ balcony doors/ curtains)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. was recorded and evidence of higher thermal sensation was found. Window /door opening behaviour was found to have improved in tenements with windows/ doors/ balcony enclosures fitted with additional metal grill shutters and/or bamboo screens. Assumable, these simple structural adaptations have improved the safety and privacy of the indoor space, encouraging the occupants to open the windows/ doors adaptively during the period of discomfort. Application of bamboo screens to balconies prevented radiant heat gain and the hot breezes from blowing from the exterior while allowing slight air movement indoors, relieving much of the thermal

were found to be highest in RE flats. More importantly, their use continued beyond the summer also in RE flats, while it had stopped in LF flats after summer. Their use put a constant demand for much cooler indoor temperatures and resulted in thermal indulgence of the occupant. On the contrary, use of fans was found to be higher in LF flats. This was due to the fact that, ceiling fans re-circulated the hot air accumulated beneath the ceiling, aggravating discomfort. Hence, the subjects in RE flats preferred coolers and air conditioners or in a few cases, pedestal fans to ceiling fans. Importantly, use of coolers and A/c s brought the indoor temperature close to the skin

Figure 5: (A) Distribution of controls available and in use (All data); (B) Change of proportion of controls in use with thermal sensation (%) (All data) (pf = proportion of fans in use; Aclr = air coolers; paclr = proportion of air coolers in use; pac = proportion of air conditioners in use)

stress caused during the overheated period. 3.3. Use of fans conditioners

air

coolers

and

air

To achieve indoor comfort in naturally ventilated apartments, occupants also adaptively used various electrical controls like ceiling fans, air coolers and air conditioners etc, [10]. The use of controls also depends on the indoor and outdoor temperatures. The effect of air movement on comfort is equivalent to a drop in indoor temperature of up to 4°C. Ceiling fan is the most commonly used lowenergy environmental control and is significant to human thermal comfort. Raja et al [10] present a very interesting fact on the use of fans, that in buildings with lesser open windows, people resort to using electro mechanical controls like fans higher. This finding corroborates the finding of Hwang et al, [12]. While all the surveyed environments were fitted with fans, only about 28% of them were fitted with air coolers, where as the availability of air conditioners was higher (42%). The occupants in this study were found to be using the fans, coolers and air conditioners as the discomfort/ indoor temperature increased. However, their use varied substantially among different buildings and subject groups (Fig. 5). Understandably, use of air coolers and air conditioners was found to be highest in higher economic groups (Gr-1 and Gr-2). It was observed that the indoor temperatures in RE flats were higher than their lower floor counterparts, due to the intense solar heat gain from the roof. Moreover, other adaptive semi-permanent controls required for thermal comfort were also found to be inadequate/ missing. As a result, availability/ use of air coolers, and air conditioners

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temperature, (32 – 34 °C) relieving much of thermal distress. Coolers and A/cs were beginning to be in use when the mean outdoor temperature was around 28.5- 31.3 °C. Higher first cost and maintenance were found to be the major impediments in using the air conditioners. A detailed discussion on the use of electrical controls is presented in Indraganti [13]. 3.4. Semi-permanent Structural Adaptation Use of semi permanent controls was found to be very important to maintain the indoor micro climate. Their use and other aspects related to their use were recorded in the transverse survey. It was found that the occupants of flats have used some semi permanent controls adaptively, to control the heat flow. It is inferred that the use of plants in the immediate exterior is most commonly adopted control measure whereas, wetted khus mats, reflective paint on the roof, roof wetting and interior plants are found to be least in use (fig.6, fig.7). It is imperative to note that plants in the immediate exterior are used by the subjects more as an ornamental feature than in response to the thermal stimuli. An expensive treatment like sun control film on the windows is adopted very highly by the occupants in KD than by other occupants (69% ~ 0%). Floor wetting is adopted by the subjects more as a routine practice, than as an adaptive thermal control measure (36% ~ 5%). It is interesting to note that a simple but effective adaptive measure like the use of wetted khus mats has not been found to be in use in any of the apartment buildings studied. This is possibly due to the problems associated with the procurement and maintenance of this control measure.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 6: Distribution of semi-permanent controls adopted by the occupants in different apartment buildings – transverse survey

In the roof exposed (RE) flats (fig.7), the use of false ceiling is found to be mostly in use only in higher economic groups, viz: GR-1(KD) and GR-2 (SA, RA), while simple measures like roof wetting and reflective paint on the roof were not used much. On further investigation during the survey it was found that, most of the occupants were unaware of the efficacy of these controls, and that the false ceiling is used mostly as part of the interior decoration. A few occupants have extended the shade to the windows adaptively, while a few subjects in KA have wetted the roofs in the evening in May. Interestingly, tenant occupied flats were least fitted with such

Figure 7: Distribution of semi-permanent controls adopted by the occupants in different apartment buildings – transverse survey

semi-permanent environment controls. More importantly, most occupants were ignorant about the efficacy of these simple semi-permanent controls in containing excessive heat gain through roofs in summer. This calls for knowledge dissemination and statutory guidelines, especially pertaining to the controls for roof exposed flats to achieve thermal comfort adaptively [14]. Behavioural and Psychological Adaptation As explained in section 3.1, the adaptive opportunities available to the occupants of flats were grossly inadequate in summer. Moreover, the occupants faced harsh thermal environments in summer in roof exposed (RE) flats, due to the intense solar exposure and high indoor temperature. Assumable, air conditioners offered immediate gratification from thermal discomfort. As a result, other environmental and behavioural adaptation methods were found to be little in use by these occupants. Moreover, the tolerance levels of the occupants using the A/c s were also found to be

limited. This was reflected by the lower regression neutral temperature of the RE subjects. Understandably, clothing adaptation in subjects with easy access to higher order environmental controls was found to be more dominated by fashion than thermal requirements. As a result, these subjects chose to use ensembles with higher clothing insulation. On the other hand, clothing adaptation in women was also limited by socio-cultural limitations and local practices also. Subjects in lower economic classes (KA and RS) had little access to the high energy intensive controls. As a consequence, they have adapted through clothing, metabolism (reduced activity during mid-day) physical environmental and other behavioural adaptation methods as well. On the contrary, these subjects have opened the windows/ doors, used lesser clothing like shorts and long gowns during the mid-day and moved adaptively to a cooler zone of the house, took cold water etc [15,16]. Behavioural adaptation was found to be higher in groups less exposed to lower temperatures. They have adapted through a more frequent use of a variety of behavioural control actions in summer. The most favourite adaptive behavioural actions were found to be “staying in airy place” and “drinking cold water” (fig.8). Importantly, women subjects, and older subjects

Figure 8: Proportion (%) of use of various Behavioural adaptation actions: indicating these actions in very limited use in the monsoon months of June and July than in the summer month of May.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. (>40yrs), and subjects in intermediate and lower economic groups and owners have shown higher proclivity to various modes of adaptation. They have accepted the thermal extremes that were encountered in domestic environments better and have displayed thermal empathy. As a result, subjects expressing thermal empathy tolerated thermal adversities better. As shown in Fig. 8, behavioural adaptation was found to be higher in summer than in the monsoon months, when thermal adversities were mitigated (June and July). It was observed that the occupants used various methods of adaption, viz: personal environmental, psycho-behavioural, clothing and metabolic adaptations to remain comfortable at high indoor temperatures encountered in summer, in addition to the structural adaptations undertaken to their home environments.

4. CONCLUSIONS Following Class II protocols, a thermal comfort field study conducted in apartments in summer and monsoon season identified that subjects adapted through clothing, activity, various environmental and behavioural adaptations to remain comfortable. The comfort temperature of the subjects was found to be way above the one specified in the Indian standards. Over 60% of the subjects were uncomfortable in summer due to the poor adaptive opportunities available to them in apartments. Fanger’s PMV always overestimated the thermal sensation. More importantly when the adaptation methods were inadequate, as in summer, the subjects especially in roof exposed flats expressed higher discomfort and resorted to the use of high energy controls like air conditioners when these were affordable to them. Adaptive behaviour of window/ door opening was critically impeded by privacy and security which in turn adversely affected the indoor temperature and thermal comfort indoors. In addition, several other impediments were noted in the adaptive use of various other controls. The importance of occupant’s adaptive behaviour for achieving thermal comfort was highlighted in this analysis. Therefore, to achieve sustainable indoor thermal comfort, this study calls for special adaptive measures for apartments, especially in the top floors to enable subjects to remain comfortable even at high temperatures.

5. ACKNOWLEDGMENTS I wish to profoundly thank Hom B. Rijal, of Institute of Industrial Science, University of Tokyo, Michael Humphreys and Nicol Fergus of Oxford Brooks University Kavita D Rao of JANFA University, India and VS Prasad Indraganti for their help and guidance.

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6. REFERENCES [1] Sharma, M. R., and Ali, S. Tropical Summer Index—a study of thermal comfort in Indian subjects. Building and Environment, 21 (1) (1986) 11–24. [2] Bin, S., and Evans, M. Building Energy Codes in APP Countries, 2008, Seoul, Korea: APP Building and Appliances Task Force; 2008. [3] BEE. Energy Conservation Building Code 2007. Bureau of Energy Efficiency. [4] Nicol, J., and Humphreys, M. Adaptive thermal comfort and sustainable thermal standards for buildings. Energy and Buildings, 34(2002) 563572. [5] Brager, G. S., Paliaga, G., and de Dear, R... Operable Windows, Personal Control. ASHRAE transaction, Vol.110, Part 2, pp 17-35, (2004). [6] ASHRAE Handbook of Fundamentals. Atlanta: American Society of Heating Refrigeration and Air-Conditioning Engineers Inc, 2005. [7] Indraganti, M., “Thermal comfort in naturally ventilated apartments: Findings form a field study in Hyderabad”, Applied Energy 87 (2010) 866–883 [8] Indraganti, M., “Using the adaptive model of thermal comfort for obtaining the indoor neutral temperature: Findings form a field study in Hyderabad”, Building and Environment 45 (2010) 519–536 [9] BIS. National Building Code. Bureau of Indian Standards; 2005. [10] Raja, I., Nicol, J. F., McCartney, K. J., & Humphreys, M. (2001). Thermal comfort: Use of controls in naturally ventilated buildings. Energy and Buildings, 33 (2001) 235-244. [11] Indraganti, M. (2009a). Adaptive use of Natural ventilation for thermal comfort in Indian apartments. Building and Environment 45(2010)1490-1507. [12] Hwang, R.-L., Cheng, M.-J., Linc, T.-P., & Hod, M. C. (2008). Thermal perceptions, general adaptation methods and occupant's idea about the trade-off between thermal comfort and energy saving in hot–humid regions. Building and Environment (2009; 44(6):1128-34. [13] Indraganti, M., “Behavioural adaptation and the use of environmental controls for thermal comfort in apartments in India”, Energy and Buildings 42 (2010)1019-25 [14] Indraganti, M. Thermal comfort and adaptive use of controls in summer: An investigation of apartments in Hyderabad. Hyderabad: PhD Thesis, JNAFA University, India, 2009. [15] Heidari, S. New Life – Old Structure. Windsor Conference (2006). http://nceub.org.uk/uploads/Heidari.pdf. [16] Rijal, H. B., Yoshida, H., and Umemiya, N, “Investigation of the thermal comfort in Nepal”. Building Research and sustainability of the built environment in the tropics. Jakarta- Indonesia: International Symposium, 14-16 October 2002

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011)

ISBN xxx-x-xxxx-xxxx-x @ Presses universitairesLouvain-la-Neuve, de Louvain 2011 PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Belgium, 13-15 July 2011.

The climate/comfort comparison and the basis of sustainable design. Impact of climate change and technological development. Luca FINOCCHIARO1, Mark MURPHY2, Tore WIGENSTAD2, Anne Grete HESTNES1 1

Department of architectural design history and technology, NTNU, Trondheim, Norway 2 Sintef Building and infrastructure, Trondheim, Norway

ABSTRACT: The comparison between climate and comfort represents the basis of sustainable design and determines the grade of complexity coming across the design process. A relatively simple approach, aiming to maximize solar heat gains and minimize thermal losses during the whole year, traditionally characterized bioclimatic design in cold climates. Today, however, the use of stringent envelopes in combination with the elevated internal gains that characterize office buildings is questioning traditional assumptions and implying the use of strategies for cooling, ventilation and solar control also in cold climates. Most of those strategies in order to work properly require external conditions sometimes not available in cold countries. These contradictions are leading architectural design of cold climates office buildings into a new complexity. In this study the results of an analysis conducted on the impact of climate change and technological development of new architectural components and materials on sustainable design are presented. The study shows how the comparison between climate and comfort could be integrated with the evaluation of the increase of temperatures due to internal heat production. This method provides useful information about natural ventilation and cooling strategies and their increased potential. Keywords: cold, climate, comfort, office, psychrometric

1. INTRODUCTION The comparison between the exterior and the desired internal comfort conditions represents not only a fundamental tool to define which passive strategies should be adopted inside a certain climatic context but also influences the grade of complexity of the design process. In order to ensure proper comfort conditions, a relatively simple approach, aiming at maximizing solar heat gains and minimizing thermal losses during the whole year, traditionally characterized architectural design in cold climates. New regulations in force, aiming at improving the environmental behaviour of the building stock, are however today implying the use of extremely stringent envelopes, characterized by a high air-tightness and insulation. The use of these envelopes permits to significantly reduce the heating demand in wintertime but, when combined with elevated internal loads, can generate overheating problems in the hot season. The use of cooling equipment has for this reason become a “must” even in extremely cold climates, significantly increasing the energy demand of office buildings. This is not questioning the convenience of using such hermetic envelopes, still giving big advantages for environmental control, but leading the architectural design of cold climates office buildings into a new complexity. Passive strategies once peculiar of different climatic contexts are today, in fact, expanding their geographic boundary of applicability to colder regions. This implies a reflection on the whole architecture of this functional typology, questioning traditional assumptions around their design in such climatic context [8]. In such a scenario an even higher grade of uncertainty is arisen by climate change that forecasts

an increase in the mean temperatures and precipitations within the next decades [1]. Environmental sensitivity of the architectural form and adaptability to changing external conditions is therefore fundamental to ensure energy efficiency. Inside this scenario, which one is the real impact of climate change and technological development on the architectural design process of low energy buildings? In this study the results of analyses conducted on the comparison between the environmental requirements of office buildings and cold climates is presented. The impact of climate change and the use of stringent envelopes on this comparison was investigated. The analysis and comparison of the climate with the human comfort requirements is usually done through the use of the psychrometric chart where both climatic conditions and comfort requirements can be plotted. This diagram becomes in this study an essential tool for evaluating also the shift of temperatures due to internal gains. All the simulations served as preliminary analyses for the project of refurbishment of the Venstres office building, located in Oslo, developed by two students at the department (fig.1).

Figure 1: The Venstres Hus office building, Oslo.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The shift of temperatures generated by the internal heat gains “imprisoned” inside the envelope has been plotted on the psychrometric chart thanks to the use of a weather analysis tool (usually based on monitored data but this time forced to analyse data created and imported from a different software) in combination with TRNSYS (simulation software able to evaluate the robustness of the different variables considered in the analyses). The new range of T and w values calculated in TRNSYS become the basis on which determine the proper passive strategies to cope with overheating problems and calculate the increase of hours spent within the comfort zone (evaluated by the weather tool on the base of a comparison with the thermal neutrality zone defined by Szokolay [5]).

2. THE CLIMATE/COMFORT COMPARISON In the physical acception of the environment the comparison between climate and architecture, basis of sustainable design, has three main protagonists: the external conditions – determined by the interaction between the climatic factors and the natural and built environment - the comfort requirements of the interior spaces, and the envelope - climatic moderator between the first two entities. The shell, commonly integrating different measures for improving the environmental behaviour of the architectural form, regulates the thermal exchanges and interactions between the first two protagonists, exterior and interior, between climate and architecture. Thermal corrections caused by the shell should aim at creating internal environmental conditions as close as possible to the desired comfort requirements. The main focus of this study is the sustainable design of low energy office buildings [2] and the selection of the different low energy strategies that could be used in a specific climatic context (Oslo, 59°55′N 10°45′E). The hypothesis is that the thermal corrections caused by elevated internal loads that characterize this functional typology, in combination with the use of stringent envelopes (respecting the regulations today in force), is questioning the appropriateness of a direct comparison between the comfort zone and the external climatic conditions and subverting traditional assumptions around architectural design of cold climates office buildings. The natural deviation of the main temperatures due to the elevated thermal gains has in fact to be plotted and analysed inside the Psychrometric contextually with the comparison between climate and architecture. This would give evidence of the increased need for cooling in cold climates office buildings and provide useful information about the use and potential of natural ventilation and passive cooling strategies, leading the architecture of cold climates office buildings into new scenarios. Analyses were conducted on an intermediate plan of the Venstres building in TRNSYS and were used as preliminary analyses for a refurbishment of the building aiming at improving its environmental behaviour. Main focus of these first analyses was therefore the quantification of this shift of

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temperatures and its representation inside the psychrometric chart in a scientific way. This thermal correction based on the respect of the regulations today in force in Norway, was assumed as a system of measures already embodied in the DNA of new office buildings, and was assumed as a starting point for defining the potential and convenience of integrating new systems. 2.1. Climate change and potential of strategies for cooling and natural ventilation On the basis of a study conducted by the RegClim authority in Norway, a significant increase in the mean temperatures and precipitations is going to affect the country within the next decades [1]. This will be even more evident in the western coast where most likely climate change will lead to hot and humid summer periods. According to this study the climate of Oslo will get close to the present Goteborg one within the next 10 years and to the Copenhagen one within the next 60 years. This shift of temperatures will extend the overheating problems over a longer period than today. Compared to Oslo, Copenhagen is in fact characterized by less rigid winters and longer warm seasons (from May to August temperatures might scarcely exceed the comfort zone). The deviation between the comfort zone and the distribution of the climatic conditions during the whole year determines the number of heating and cooling degree-hours. A comparison between Oslo and Copenhagen shows however that the forecasted increase in temperatures would result in a significantly lower number of heating degree-hours in the colder months but not in the cooling degree-hours in the warmer ones (Fig.2).

Figure 2: Oslo and Copenhagen: Hourly temperature profile. Heating and cooling degree hours.

This means that the use of strategies for cooling and natural ventilation is not yet required for a significant number of hours. The increase of temperatures due to climate change will affect also the potential of the strategies for natural ventilation and cooling in the overheated months. In fig. 3 this variation of the potential is translated into a percentage increase in the number of hours spent within the comfort zone each month (calculated using

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

the monthly thermal neutrality zone defined according to Szokolay formulas). The use of the psychrometric chart suggests the same low energy strategies - passive solar heating and thermal mass for most of the year - for both Oslo and Copenhagen. In an intermittently used and heated building, like an office, however, massive construction might imply longer heating up periods in the morning and the stored heat would be dissipated overnight, thus wasted. Light materials might therefore result more convenient. The eventual increase of temperatures just affect then, to a small extent, the environmental behaviour of the building and the efficiency of the strategies adopted but do not suppose the use of different strategies. Natural ventilation and cooling strategies still maintain a relatively low potential, being able to increase the percentage of hours spent within the comfort zone only of a small quantity (Fig. 3). These results seem to clash with empirical experience about the increased need for cooling of office buildings. Further analyses are therefore necessary for this typology. The heat produced by internal gains has to be plotted as a thermal correction inside the psychrometric chart giving evidence of the increased need for cooling. Control potential zones and CPZ and comfort percentages increases will be evaluated only in a second moment after these preliminary estimations.

 

3. METHODOLOGY Different simulations have been performed on a virtual model of the Venstres office building using the following group of characteristics reported in table 1 (existing building characteristics, TEK10, PfNS3700 Passivhus standard). All the simulations have been performed assuming the building working five days a week - from 8 a.m. to 8 p.m. – without any sort of HVAC artificial system for environmental control. This has been done in order to quantify the spontaneous variation of air temperature and relative humidity in the interior spaces due simply to the constructive characteristics of the building. The air changes rate has been fixed, in accordance with the Norwegian 3 2 regulations in force, as 6 m /(m *h) that, considering the height of 2,8 meters of our office building, can be easily converted into 2,14 air changes per hour. During the other 12 hours of the day when the building is not active the ventilation airflow has been assumed being 1,0 ach. TRNSYS have been used first in order to calculate the variation of temperature and relative humidity all along the year (8760 hours). Values have been then exported through Excel to the Weather-Tool that permitted to plot them on the psychrometric chart. Table 1: Families of parameters used for the simulations.

U-value extern. wall U-value floor on gr. U-value roof U-value windows Air tightness Cooling set temper. Heating set Temper. Occupancy Lighting load Equipment load Hours of operation

unit

Exist.

TEK10

prNS3700

2

0.96

0.18

0.18

2

0.40

0.13

0.13

2

0.40

0.15

0.15

W/m K

2

2.8

1.2

0.8

ach

3.0

1.5

0.5

°C

18

18

18

°C

26

26

26

m /p

10

10

10

W/m

2

11

11

5

W/m

2

8

8

6

12/5

12/5

12/5

W/m K W/m K W/m K

2

h/d

4. RESULTS

  Figure 3: Oslo and Copenhagen: psychrometric chart and percentages of hours spent in the comfort zone.

The results, presented in figures 4, 5, and 6 show how the spontaneous increase of temperatures due to the internal gains is related to the specific characteristics of the envelope (u-value and airtightness of Existing building, TEK10, PrNS3700). Internal gains due to IT equipment and lighting have been assumed, in a first time, equal to 19 W/m2 (11 W/m2 lighting + 8 W/m2 equipment). In a second sequence of analyses the simulations have been 2 performed with lower internal gains, 11 W/m ,

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

corresponding to best practice according to Marton Varga [6] and in respect of the Passivhus standards (5 W/m2 lighting + 6 W/m2 equipment). Occupancy 2 has always been assumed being 10 m /person for both groups of simulations.

 

Figure 4: Spontaneous shift of temperatures due to internal 2 gains (19W/m lighting+equipment, 10 occupancy)

The diagram represented in fig. 4 shows that the shift of temperatures due to internal gains is larger the more stringent the external envelope is. It has to be considered that TRNSYS calculate temperatures and relative humidity variations starting from an arbitrary initial point (20°C; 50%). That’s why in figures 4 and 5 the temperature profile of January is significantly higher than the other cold months. As reported in the legend in the bottom the sequence of three shifts of temperatures has been represented with different tones of gray, going from the lighter one of the Existing building parameters up to the almost black of the Passivhus prNS3700 standard. Figure 6: Spontaneous shift of temperatures due to internal 2 gains (19W/m lighting+equipment, 10 occupancy). Psychrometric chart and heating and cooling degree hours.

5. CONCLUSION

Figure 5: Spontaneous shift of temperatures due to internal 2 gains (11W/m lighting+equipment, 10 occupancy)

Once the shift of temperature has been calculated, the values have been plotted inside the psychrometric chart in order to relate them to the thermal comfort zone (Fig.6). The new range of temperatures and relative humidity values represent the new starting point for calculating the increase of hours spent inside the comfort zone thanks to the use of the different passive strategies. This increment, as mentioned above, is calculated by the weather-tool comparing the T and w distribution with a thermal neutrality zone calculated according to Szokolay formula. This fundamental step gives evidence of the implications of the increased need for cooling on both process and product of sustainable design.

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On the base of the analyses conducted the direct comparison between climate and comfort, commonly assumed as the basis of sustainable design, might in certain circumstances result not sufficient. Sustainable design of low energy office buildings require further analyses in order to cope with the increased need for cooling due to the elevated internal gains. Such preliminary analyses - climatecomfort comparison and increase of temperatures evaluation – are in this study integrated. The comparison between the comfort zone and the new range of values of T and w calculated above become the starting point for defining strategies and calculating their potential. This shift of temperatures, as seen, is strongly related to the specific characteristics of the envelope and can imply the use of strategies completely different from the ones suggested by a direct comparison between climate and comfort. The significant increase of the CDH (fig.7) gives even more strength to the necessity of using strategies for cooling and ventilation, today extending their geographic boundaries of applicability to cold climate regions.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 6. CONSIDERATIONS ON SUSTAINABLE DESIGN PROCESS AND ITS PRODUCTS

Figure 7: Exterior – Oslo – and interior – OSLO+prNS3700: Psychrometric chart and passive strategies.

Figure 8: Exterior – Oslo – and interior – OSLO+prNS3700: Increase in the percentage of hours spent within the comfort zone in case different passive strategies are applied.

The study conducted implies a reflection both on the process of sustainable design and its product. Implications on the process concern the need of quantifying the potential thermal deviation coming from the internal thermal loads including it in the preliminary climate-comfort comparison. In the case of office buildings this deviation represents a force strong enough to completely upset the whole architectural concept of the building. The increased potential of strategies for passive cooling and natural ventilation, together with the larger number of cooling degree hours, suggest and justify a new approach in architectural design of low energy office buildings in cold climates. The permeability of the envelope, required by the use of strategies for cooling and natural ventilation, is not in contrast with the tendency of adopting even higher low energy standards and is not calling TEK10 or PrNS3700 standards into question. Control of the thermal exchanges happening through the envelope is essential for reducing the heating demand in wintertime. The new fundamental requirement is, instead, environmental adaptability to changing conditions, not only of the envelope itself but of the whole architectural form. Most energy efficient office buildings today take advantage of the free heat produced inside the interior spaces by the thermal loads. Heat is usually used for partial heating of the outside air before letting it inside the building by means of a heat exchanger. This results in significant energy savings. Other buildings take advantage of intermediate spaces able to give the architectural form a deeper environmental sensitivity. Adaptability is in this case enhanced translating the potential microclimate generated by the interior heat production in an intermediate space included between the interior and the exterior. This type of space is usually characterized by different phenomena, like the greenhouse effect or thermal air stratification that influence its environmental behaviour. Intermediate spaces can have several forms: they can be as thin as a blades – double skin facades - or as thick as a liveable plazas or atriums. What is more important for the definition of the low energy strategy, is that the perimeter of the building takes possession of small fragments of exterior spaces whose environmental conditions can be controlled. Intervening in the interaction between climate and architecture is now possible in two different steps; firstly acting in the interaction between the climate and the microclimate of the in-between space and secondly in the interaction between the microclimate and the internal spaces (Fig. 8). The microclimate generated inside the gap is usually controlled through different passive strategies, and can, given its geometrical and specific characteristics, have completely different environmental behaviours. Its thermal conditions can take advantage of the possibility of dialoguing with both the external and internal spaces. The contribution of the first skin, including both internal and in-between space, can, when required and convenient, be cancelled re-establishing a

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

microclimate equal to the exterior thermal conditions. Such qualities of intermediate spaces enhance environmental sensitivity and adaptability of the architectural form. The thermal comparison is also split in two different steps (fig.9) .

  Figure 9: Sustainable design process

7. ACKNOWLEDGEMENTS This paper has been written within the ongoing SINTEF project ‘‘LECO” on low energy commercial buildings. The authors gratefully acknowledge the Research Council of Norway.

8. REFERENCES [1] T. Iversen et al., RegClim Norges Klima om 100 år, Usikkerheter og risiko (2005). [2] M. Haase, I. Andersen, B. Time and A.G. Hestnes. Design and future of energy efficient office buildings in Norway, Building simulation conference (BS09), Strathclyde (2009). [3] M. Haase and I. Andersen, The role of passive cooling strategies for Norway. The international journal for climate change. Impacts and responses. Volume 1, Number 3, Common ground Publishing, (2009) pp. 2x2–2x4. [4] Standard Norge, Norsk Standard NS3031:2007. Beregning av bygningers energytelse, Metode og data, Pronorm ed. Lysaker (2007). [5] Steven V Szokolay, Introduction to Architectural Science. The basis of sustainable design, Architectural press, (2008) [6] Marton Varga, Keep Cool. Internal heat loads, Osterreichische Energiagentur – Austrian Energy Agency (2009). [7] V. Olgyay, Design with climate: bioclimatic approach to architectural regionalism, Princeton University press, Princeton, N.J. (1963). [8] L. Finocchiaro, T.Wigenstad, A.G. Hestnes, Relation between form and energy consumption in Low Energy office buildings. CLIMA2010 conference, Antalya (2010).

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ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Delivering Quality Indoor Environment in Houses The Potentials and Impact of Building Materials for Facade Design in Cairo Wael SHETA 1,2, Steve SHARPLES3 1

2

University of Sheffield, School of Architecture, Sheffield, United Kingdom. Al-Azhar University, Department of Architecture, Faculty of Engineering, Cairo, Egypt. 3 University of Liverpool, School of Architecture, Liverpool, United Kingdom.

ABSTRACT: This paper investigates the building materials which have been used in residential buildings for one of the new communities around Cairo. The study examines the thermal performance of existing building materials which have been already used by architects for building façades, and then uses the dynamic energy simulation package DesignBuilder to try and improve the quality of the environment inside these developments. Visual surveys and walkthrough investigations were carried out to determine building materials and construction techniques and 3D models of the dwellings were created incorporating the building materials and thermal properties which had been used. Alternative facades and materials were then applied and indoor thermal comfort temperatures assessed. Keywords: Building materials, indoor environment, dwellings, thermal comfort, building simulation.

1. INTRODUCTION Improving the thermal performance of buildings has a great impact upon the built environment. It is one of the biggest challenges facing architects and designers nowadays, especially with the growing concern over the environment and the necessity to find more sustainable communities for future generations. Building performance has become a significant issue around the world, not only in developed countries but also in the developing countries - it enhances the quality of indoor environment and thermal comfort for occupiers and improves the image and the concept of the sustainable community, which is still one of missing links in new Egyptian buildings. Taking a wide overview of the dwellings in new urban communities around Cairo which have been built during the last ten years, one can find a clear disparity and contradiction between materials used in construction and the architectural solutions for facades, taking into account their compatibility with the existing place and environment. Architects have found many architectural designs for dwellings and facades, despite the restrictions in plots area and very prescriptive regulations. Most of these designs give the priority to form and number of spaces. They do not take into account building performance and environmental conditions to maintain a quality indoor environment. This was due to many reasons, one of the most important being that there is no valid knowledge of the appropriate technologies and building materials which can be used to achieve the goal of sustainable buildings that have a quality indoor environment in Egypt. Many strategic decisions can be taken to reduce the heat gain when a façade is designed. The façade can play the role of environmental filter. This means great care must be taken in the choice of the wall

materials with respect to their physical properties. Within this context, building simulation can be used as a tool to help analyze and predict building performance and sustainability and also to indicate how improved environmental design can enhance the sustainability of buildings and communities. DesignBuilder was chosen to simulate the thermal performance of these houses for a range of design strategies, including the use of different building materials, wall constructions and an array of orientations. The fundamental aim of this paper is to test the behaviour of different building materials and wall constructions under Egyptian climatic conditions to help the choice of these materials more effective from an environmental standpoint to improve the thermal behaviour of new housing. Architects, designers and engineers can be given sustainable design guidelines to enable appropriate solutions to be chosen at the early stages of a design to achieve low energy thermal comfort.

Figure 1: Two-flats /floor building type facades.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

2. BUILDING CHARACTERISTICS 2.1. Visual survey This paper studies one of the new urban settlements that have been developed around Cairo, El-Tagammu' El-Khames, which is considered to be the new premium residential district of Greater Cairo. The study focuses on dwellings as they represent the main sector of this community. The two-flats/floor building types shown in Figure 1 are typical of many residential properties found in this settlement, and that is why it was selected as a case study. This building consists of a ground floor with an area of 300 square meters and two typical floors with an area of 330 square meters each. All floors contain two identical units facing each other. Living space has been selected to be examined as it is the most attractive area for occupiers and it combines living, dining and entertainment activities. In addition, it is the most adjacent zone of the building to the main facade. Field investigations for some of these types of dwellings have examined the thermal behaviour of this type of building. Excessive heat gain has occurred in buildings for long periods of the day and exceeds the comfort zone for the Egyptian climatic conditions. This result confirms the view that these building designs do not take into account climate, site and environmental conditions to maintain a quality indoor environment. In addition, a visual survey was carried out by the authors to analyze the façade, constructional features and explore the appearance of the community. The building materials which were used in the main façades were identified.

Figure 2: Construction techniques and building materials.

2.2. Building material and construction A wide range of building materials and construction techniques has been used. Concrete has been used widely for construction rather than steel - this was due to many factors, such as the price, easy of moulding and operational quality. Cement and ordinary red brick are the most common materials used to construct a building’s external and internal walls (see Figure 2). Most of the external walls are single skin. Double walls are rarely used but cladding on the walls is common. The thickness of the walls are defined according to the brick dimensions (250×120×60 mm) i.e. a wall with 120 mm thick, the so-called Nos toba or half brick, and

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the wall which is 250 mm thick, the so-called Toba (single brick) and so on. A vast range of natural stones are used in cladding that includes different types of marble, granite and limestone. In addition a wide range of paint types and colours are utilised. Glass was also used in many different types, thicknesses and thermal properties. The usage of all these materials partly depends on the owner’s viewpoint, his financial ability or the architect’s view of the market and the design. There is little thought about the impact of their choices upon thermal comfort inside the building. Thermal properties for building materials, The thermal properties (density, conductivity and specific heat) for building materials that are commonly used in construction in Cairo are shown in Tables 1 and 2. Table 1: The thermal properties (density, thermal conductivity and specific heat) of building materials commonly used in construction in Cairo [1].

Building Material

Density kg/m³

Therm Cond. W/mK

Specific Heat J/kgK

Red Brick (S)

1790

0.60

840

Red Brick (H)

1950

1.00

829

Cement Brick (S)

1800

1.25

880

Cement Brick (H)

1130

1.60

880

Ytong Brick (Khafaf)

985

0.33

850

Sand Brick (S)

1800

1.59

835

Sand Brick (H)

1500

1.39

811

Table 2: The thermal properties (density and thermal conductivity) of cladding materials commonly used in construction in Cairo [1].

Building Material

Density kg/m³

Therm Cond. W/mK

Lime Stone

1650

0.93

Sand Stone

2000

1.30

Marble

2600

2.60

Granite

2650

2.90

Cement Rendering

1570

0.95

Gypsum Plastering

1200

0.42

Rough Lime Plastering

1440

0.16

3. METHODOLOGY 3.1. Overview The relationship between building materials and indoor thermal quality has been widely investigated; one can find it as a common denominator in most of the literatures that addresses building envelope or passive solar techniques in architecture. Oral et al. [2] investigated built and physical environment relationships by reporting building materials as one of the most critical parameters influencing the design of the building envelope. Behsh [3] tried to find a relationship between the U-value and thermal storage capacity in a study of structure behaviour in a Mediterranean region. Thomas et al. [4] conducted a study about the key parameters for selecting

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Three sets of external wall construction have been chosen. Single wall, double wall and cladding wall construction. Each set represents the U-values of 0.5, 1, 1, 5 and 2 W/m²K as it is shown in Figure 3. Tables 4,5,6 and 7 show all sets of wall constructions for U-Value 0.5,1,1.5 and 2 W/m²K respectively. Table 5: All wall constructions with U-Value of 1.0 W/m²K.

Building Material Single

affordable materials and designing for thermal comfort for housing in Egypt. Okba [5] discussed building envelope design as a passive cooling technique for buildings in Egypt. He highlighted that great care must be taken in the choice of building materials for façades and roofs in hot climates. Physical properties such as thermal conductivity, resistivity and optical reflectivity must be taken into account. In addition, one of the recent studies of the thermal properties of building materials by Clarke et al. [6] presented the outcome of a large project to describe the variation of building thermal properties as a function of temperature and moisture content.

35

1.Brick work

100

2.Air gap

10

3.Ytong brick (Pumice) 4.Cement render and paint

150 15

1.Limestone

50

2.Cement render

20

3.Ytong brick (Pumice)

250

4.Cement render and paint

15

Table 6: All wall constructions with U-Value of 1.5 W/m²K.

Building Material

Thickness (mm)

30 20

3.Brick work 4.Cement render and paint 1.Brick work

250 15 120

Single

1.Lime sand plaster

10

60

120 15

35

1.Limestone

50

1.0

315

265

335

70

1.5

285

275

335

0.5

485

480

515

1.Thermal plaster

50

2.Ytong brick (Pumice)

400

3.Thermal insulation 4.Cement render and paint 1.Thermal plaster

20 15 30

2.Ytong brick (Pumice)

200

20

3.Brick work

250

4.Cement render and paint

15

Table 7: All wall constructions with U-Value of 2.0 W/m²K.

Building Material

Thickness (mm)

1.Thermal plaster

20

Single

Thickness (mm)

2.Cement render

2.Cement render

30

3.Brick work 4.Cement render and paint 1.Brick work

120 15 50

Double

90

Cladding

∆W

2.Air gap

10

3.Air gap

15

4.Ytong brick (Pumice)

200

5.Thermal insulation 6.Cement render and paint

20 15

1.Limestone

50

3.Brick work 4.Cement render and paint

50 15

2.Cement render

30

1.Limestone

50

3.Ytong brick (Pumice)

400

2.Cement render

30

4.Thermal insulation

20

3.Brick work

120

5.Cement render and paint

15

4.Cement render and paint

15

Cladding

Single Double

200

3.Cement render and paint

3.Brick work 4.Cement render and paint

W3 Cladding 215

Table 4: All wall constructions with U-Value of 0.5 W/m²K.

Cladding

2.Ytong brick (Pumice)

2.Air gap

2.0

W2 Double 125

Building Material

50

2.Cement render

W1 Single 205

U-Value

1.Thermal plaster

Double

Table 3: The thickness of all types of walls in mm and (∆W), the difference between the width of the thicker wall and thinner wall in each set.

Cladding

The purpose of the present paper is to investigate the impact and the potentials of different types of wall materials with different thermal transmittance value (U-Values) as related to Egyptian climatic conditions. The method adopted for this investigation was based on two criteria - the first is the minimum thickness of the external wall, which has been set as 120 mm or half brick. The second is the difference of the wall thickness (∆W) i.e. the difference between the width of the thicker wall and thinner wall in each set, which should not exceed 100 mm in each set of wall constructions. Table 3 shows the thickness of all types of walls and (∆W) the difference between the width of the thicker wall and thinner wall in each set.

Double

3.2. Criteria

Thickness (mm)

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Egypt from 26th of June to 2nd of July. 26th of June has been selected as a summer design day which represent the most extreme hot conditions that may occur. Figure 5 illustrates the results for indoor and outdoor temperatures from DesignBuilder. The results from building simulations for all three sets of wall construction techniques have been gathered. All living spaces in the southern facade for the whole building were simulated and temperature profiles for the ground, first and second floor were analyzed.

Figure 3: All sets of wall constructions and U-values

3.3 Modelling and simulation Package The software package being used in this study was DesignBuilder version 1.8. It uses as its calculation engine Energyplus 2.2, a powerful thermal simulation package developed by the US Department of Energy. EnergyPlus has been extensively tested and validated analytically [7]. Sheta and Sharples [8] tested and validated DesignBuilder as a satisfactory simulation package with which to perform sustainability analysis and thermal assessment for dwellings in the new Cairo community. The credibility of the simulation results allows the use of DesignBuilder in many parametric studies. Some 3D models of the dwellings (Figure 4) were created using the building materials and thermal properties described earlier. Southern facades have been chosen since they receive large amounts of heat gain. The window to wall ratio was 20%. Glazing area has been set as 80% with 50% glazing opening area. All simulations were undertaken in free running mode without any heating or cooling systems operating.

Figure 5: The results for indoor and outdoor temperatures from DesignBuilder [9].

Figure 4: Two-flats /floor building model in Designbuilder (Living space-typical plan- whole building).

4. RESULTS AND DISCUSSION Simulations have been run for the for the hottest week of the year which represents the summer season, i.e. summer design week which lasts in

4

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The initial findings from the temperature profiles for the ground, first and second floor respectively show that there is a significant difference between the eastern and western flats which both have southern facades. Living spaces for south west flats showed a bigger variation in temperatures compared to south east flats. This variation has appeared in all sets of wall constructions for all floors and was clearly noticed in the ground floors, which can be interpreted as a result of the sun’s path during the summer and afternoon heat gains occurring on this side of the building that last from noon to sunset for at least 6 hours a day. That means great care must be taken for the treatment of the south west façade. Shades, blinds and overhangs, in addition to windows ratio, should be taken into account at the initial design phase to decrease temperatures inside these spaces.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

In terms of thermal comfort and building behaviour under Egyptian climate conditions, there are a number of points worth noting. Results for all sets show that extreme heat gain occurred in the building during the day time in the hot summer season. For the ground floors, all temperature profiles for all sets of the wall constructions with UValues 0.5, 1 and 1.5 W/m²K have almost the same trend, which was clearly revealed in both south east and south west flats. Although the small difference between all sets did not exceed 0.5 ºC, the single wall construction was always revealing the lowest temperature profile among all sets. The temperature profile for the wall construction set with a U-value of 2 W/m²K does the same but the peak hours are spread from noon to 8.00 pm, and revealed a significant difference reached 1.5 ºC. Figures 6 illustrates temperature profiles for the ground, first and second floor respectively for different wall constructions having a U-Value of 1 W/m²K facing south.

At the same time, all temperature profiles for the first and second floors for all sets of wall constructions with U-Values of 0.5, 1 and 1.5 W/m²K acted in the same way and had almost the same trend with a very narrow difference between them. The maximum temperature for the trend of U-Values 0.5, 1 and 1.5 W/m²K for all walls types were 34.3, 34 and 33.9 ºC respectively for the first floor and 36.1, 35.7 and 35.5 ºC respectively for the second floor. The minimum temperature for the trend of UValues 0.5, 1 and 1.5 W/m²K for all walls types were 30.9, 30.8 and 30.8 ºC respectively for the first floor and 32.2, 32 and 31.9 ºC respectively for the second floor. The temperature trends for all types of walls having the U-value of 2 W/m²K are almost the same. A significant difference occurred in peak hours and the maximum difference between trends reached 2 ºC. Figures 7 shows temperature profiles for the ground, first and second floor respectively for different wall constructions having a U-Value of 2 W/m²K facing south.

Figure 6: (from the top)The temperature profiles for the ground, first and second floor respectively for different wall constructions have 1 W/m²K as a U-Value facing southern facade.

Figure 7: (from the top)The temperature profiles for the ground, first and second floor respectively for different wall constructions have 2 W/m²K as a U-Value facing southern facade.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

One of the most significant findings to emerge from these results is that using different types of wall constructions having the same U-value and keeping the difference between the thicker and the thinner wall within 100 mm does not greatly effect the temperature profiles for indoor spaces. In addition, the time lag, a significant factor for the heat flow in to and out of the building, did not have much significance for these building materials and wall constructions. This gives designers confidence to use many types of building materials to explore the potential and impact of building materials for facade design in the new Cairo communities.

5. CONCLUSION This study examined a wide variety of building materials which could help achieve low energy thermal comfort for domestic buildings in hot climates. It was important to provide designers with simple criteria for material selection and to consider the options from an environmental standpoint. The study has focused attention on building materials and how thermal resistance for wall components can be a useful guide in determining the appropriate solutions for building façade design under Egyptian climatic conditions at the early design stage. The simulation results show that within the aforementioned wall thickness criteria for traditional materials, a single wall with insulation gives the best indoor operative temperature even thought there is only a narrow difference between wall sets. In addition, using a double or a cladding wall could have more significant effect when both their widths are increased by 100 mm of the width of the equivalent single wall which has the same U-Value. The narrow variances in wall construction sets when applying these criteria came from the narrow variances between thermal capacities for traditional building materials. This leads us to investigate thoroughly new building materials that have high thermal capacity. These may be more expensive and are rarely used. Finally, given that the people in this community have sufficient financial means, it would seem viable that non traditional materials could be used for walls, especially in view of their enhanced, overall thermal performance.

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6. REFERENCES [1] HBNRC, The Egyptian Code for Thermal Insulation, Housing and Building National Research Centre, Cairo - Egypt (2007). [2] G. Oral and N. Bayazit, Building Envelope Design with the Objective to Ensure Thermal, Visual and Acoustic Comfort Conditions, Building and Environment, Elsevier, 39, 281 – 287, (2004). [3] B. Behsh, Building Form as an Option for Enhancing the Indoor Thermal Conditions, Proc. The 6th Symposium on Building Physics in the Nordic Countries, Trondheim – Norway (2002). [4] J.Thomas and F. Hammad, Materials Selection for Thermal Comfort in Passive Solar Buildings, Journal of Materials Science, Springer, 41 (2006), 6897-6907. [5] E. Okba, Building Envelope Design as a Passive Cooling Technique, Proc. The International Conference of Passive and Low Energy Cooling for the Built Environment, Santorini - Greece (2005), 467-473. [6] J. Clarke and P. Yaneske, A Rational Approach to the Harmonisation of the Thermal Properties of Building Materials, Building and Environment, Elsevier , 44 (2009), 2046-55. [7] EnergyPlus,(2009). http://apps1.eere.energy.gov/buildings/energypl us/testing.cfm. [8] W. Sheta and S. Sharples, A Building Simulation Sustainability Analysis to Assess Dwellings in a New Cairo Development, Proc. SimBuild 4th National conference of IBPSA-USA, New York USA (2010), 94-101. [9] DesignBuilder,(2010). http://www.designbuilder.co.uk/

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Developing Sustainable School Design in Iran A thermal comfort survey of a secondary school in Tehran Sahar ZAHIRI1, Steve SHARPLES2, Hasim ALTAN1 1 2

School of Architecture, University of Sheffield, Sheffield, UK School of Architecture, University of Liverpool, Liverpool, UK

ABSTRACT: Sustainable school design can have a significant effect on improving the physical comfort and learning performance of pupils. Sustainable design can also reduce the long term impact of school buildings on the environment. Due to a lack of appropriate sustainable school design guidelines in Iran, it has historically been difficult to create comfortable and productive learning environments for students. In order to develop sustainable school design guidelines, it is necessary to assess the current design methods used by the educational authorities in Iran and to examine the performance of existing schools. This paper describes a series of field studies that used survey questionnaires and field measurements conducted in a female secondary school in Tehran, Iran, for three weeks. The measurements assessed thermal conditions during lesson hours in the warm spring period of April/May. 45 students in two classrooms completed questionnaires as thermal comfort variables such as indoor air temperature and relative humidity were measured. A comparative analysis was performed on the result of field studies from the classrooms, which were located on the north and south facing sides of the school. The findings indicate that most of the occupants found the thermal environment not to be comfortable during the spring. Keywords: thermal comfort, sustainability, school design, surveys, Tehran

1. INTRODUCTION Sustainable school design solutions can have a significant effect on reducing the long term impact of school buildings on the environment and also improving the physical comfort and learning performance of students as well as saving energy [1]. In order to create a comfortable and healthy indoor educational environment for students, the main subjects that need to be considered during the design process are lighting, ventilation, acoustics, and thermal comfort. Thermal conditions in the classrooms affect not only health and comfort, but also students‟ learning efficiency [2]. Providing an acceptable indoor climate in a building is necessary in order to make it more comfortable for occupants and also to control its energy consumption to make it more sustainable. Thermal comfort studies can help to frame sustainable design standards for buildings [3]. In recent years the quality of construction and school design in Iran has been improved significantly. However, most of existing schools have been constructed without concern for the thermal comfort of the occupants in classrooms. The main reason is the lack of appropriate design guidelines for creating comfortable and healthy indoor environments in Iranian schools. Thermal comfort studies show that poor thermal environment in classrooms reduce students‟ productivity. Therefore, a comfortable classroom will increase students‟ efficiency to study and reduce energy consumption of school buildings, which has been increasing in the recent years. According to the annual report of the Central Bank of Iran [4], the total number of students aged 6 to 18 was 13.51 million in 2008-09 and 135,453 schools had been built up in Iran since 1979. The statistics

indicate that there are many school buildings in Iran with large numbers of students, which underlines the importance of studying thermal comfort conditions in Iranian schools. In order to maximise students‟ ability to learn in a healthy environment, as well as reducing energy consumption of school buildings in Iran, there is a need to provide some guidelines for sustainable school design in Iran. This study will present the results of field experiments on thermal comfort in classrooms in the city of Tehran. School buildings in Tehran have been chosen as the case studies because Tehran is one of the biggest cities in Iran and, compared to other Iranian cities, has the largest percentage of students in its population. Figure 1 shows the south facade of the school.

Figure 1: South facade of the secondary school in Tehran

The main aims of the research are to identify the conditions which are considered comfortable by

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female secondary school students in Tehran and to investigate the thermal comfort and indoor air quality in the classrooms.

2. CLIMATE OF IRAN AND THE CITY OF TEHRAN Iran is a country located in the Middle East and covers over 1,648,195 km², with a land area of 1,531,595 km² and a water area of 116,600km². It extends between latitudes 25°N and 40°N and longitude 44°E and 63° E. The city of Tehran is located on the southern border of the Alborz Mountain. Tehran has hot-dry summers and cold winters. The climate of Tehran is generally characterised by its geographic location and it is usually cooler on the north side compared to the southern part. The annual precipitation is low and the average rainfall on the plain is about 218 mm and the maximum rainfall is about 50 mm in November [5]. Figure 2 shows the average annual temperature range in Tehran.

Table 1: Summary of samples

Classroom N (north facing) S (south facing) Total

Number taking part in survey 23 22 45

3.1. Objective Physical Measurement The school is located in south-west of Tehran and has four storeys. The measurements assessed thermal condition of the classrooms during lesson hours in the warm months of April and May for three weeks, 26th April 2010 to 15th May 2010, on the top floor. Thermal comfort variables such as indoor air temperature and relative humidity were measured by HOBO loggers. HOBOs were located at a height of 2.0 metres above the floor, on top of the blackboard. They were collecting indoor temperature and relative humidity with a logging interval of 15 minutes. Daily local weather data were also extracted from local weather station reports. Table 2 presents the means of indoor temperature and relative humidity as well as their standard deviations for the two classrooms. Measurement results were divided in to weekdays (W), representing 17 days, and weekends (WE), representing 3 days. Table 2: Mean indoor temperature, mean relative humidity and standard deviations in two classrooms for weekdays (W) and weekends (WE).

Classroom Figure 2: Temperature range in Tehran [6]

Moreover, relative humidity reaches 66% in December and decreases to 27% in July and also the average dry bulb temperature is 5°C in January and 32°C in July [6].

3. METHODS AND DATA COLLECTION In order to achieve the study‟s aims, a series of field studies, that used survey questionnaires and field measurements, were conducted in a four storey female secondary school for three weeks during spring. The measurements assessed thermal conditions during lesson hours in the warm months of April and May. Overall, 45 questionnaires were completed in two classrooms on the 4th May 2010 by the students. Thermal comfort variables were measured for a three week period, which included the survey date, by HOBO data loggers. HOBO loggers tracked temperature and relative humidity inside two classrooms. Details of the classrooms occupants are given in Table 1. A comparative analysis has been performed on the result of the field studies from the classrooms, which were located on the north (N) and south (S) facing sides of the school on the top floor. Later, the results from the field measurement were compared with the results of the questionnaire survey.

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N S

Mean S.D Mean S.D

Indoor temperature (°C) W WE 24.9 24.1 1.3 0.5 25.0 24.2 1.5 0.5

Indoor relative humidity% W WE 34.0 31.7 6.3 5.8 29.3 27.8 7 6.2

From Table 2 it can be seen that the mean indoor temperature, mean relative humidity and their standard deviations during the weekdays are higher than at weekends. Generally, the standard deviation of indoor air temperature is smaller than the standard deviation of indoor relative humidity. During the weekends the school does not have any occupants, which results in lower humidity levels. However, the mean temperature of the classroom rises during the weekdays, possibly due to increasing activity levels in the classrooms. Moreover, although the school has an air conditioning system, it is hardly used during the warm seasons in order to keep energy bills low. During the three week assessment, the air conditioning system was kept off and classrooms were naturally ventilated, which resulted in a higher temperature range during the weekdays. 3.2. Questionnaire Assessment of thermal comfort in the classrooms was based on a questionnaire survey. A total number of 45 students from classroom N and classroom S th participated in the survey at noon on the 4 May 2010. They answered questions on their perception of

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Indoor temp (°C) Indoor RH% Outdoor temp (°C) Outdoor RH%

Mean Standard Deviation Mean Standard Deviation

Classroom N 23.9

Classroom S 23.6

0.4

0.1

35.4

28.8

2.1

2.6

18.5 27.5

12:00

11:30

11:00

10:30

10:00

09:30

09:00

08:30

Time Indoor Temperature (°C)

4.1. Indoor Climate

Indoor RH %

40 30

23.6

20

23.4

10

23.2 23

Time Indoor Temperature (°C)

12:00

11:30

11:00

10:30

10:00

09:30

09:00

08:30

0

Relative humidity %

24 23.8

08:00

Temperature °C

Figure 3: Mean indoor temperature and relative humidity during the survey in classroom N.

07:30

Table 3: Summary of environmental data during the comfort survey in classrooms between teaching times (7:30am12pm) on the 4th May 2010.

08:00

07:30

4. RESULTS Table 3 shows the means and standard deviations of climatic variables for each classroom during lesson hours (7:30am-12:00pm) on the 4th May 2010 in classroom N and S. The result shows that the mean indoor air temperatures in both classrooms were around 23.5°C, although the mean outdoor temperature was cooler at around 18.5°C. However, the mean indoor relative humidity in classroom N was 35.4% and in classroom S was 28.8% while the mean outdoor relative humidity was 27.8%. The raised values of the internal parameters over the external values reflect the internal heat and vapour gains from student activities.

40 38 36 34 32 30 28

25 24.5 24 23.5 23 22.5 22

Relative humidity %

Figures 3 and 4 illustrate the mean indoor temperature (ºC) and mean indoor relative humidity of the N and S classrooms during the measurement period of 4th May 2010 when students answered the questionnaires. Figure 3 shows that while the indoor temperature was increasing steadily from 23.0 °C in the morning to above 24.5 °C at noon during teaching hours in classroom N, relative humidity was relatively constantly between 32% and 38%. On the other hand, figure 4 presents that indoor air temperature ranges in classroom S were changing between 23.4 °C and 23.8 °C consequently. Generally, in classroom S the temperature was steady for around half an hour in the morning, and then it was rising for about an hour, then constant for about 45 minutes and finally decreasing for around thirty minutes, reaching 23.5 °C at 10:00am. The temperature changes were then similar until noon. However, relative humidity was steady most of the time and it was around 30% till 11:00am and later it decreased to around 25% at 12:00pm. Temperature °C

thermal sensation in their classrooms using the 7 point ASHRAE scale. They also voted for their indoor thermal preferences using the 3 point McIntyre scale. Two different questionnaires were designed. One was related to the occupants‟ thermal sensation and the other was a site record form. All students filled in the first questionnaire whilst sat in their classrooms and after performing light activities such as reading or writing 15 minutes prior to the survey. The main questions were about students‟ thermal sensation on the 7 point ASHRAE scale and their thermal preference on the McIntyre 3 point preference scale as follows:  How do you feel at the moment? Cold □ Cool □ Slightly cool □ Neutral □ Slightly warm □ Warm □ Hot □  Would you like to be Cooler □ No changes □ Warmer □ Moreover, students were asked to answer questions about their clothing and activities in the preceding 15 minutes in order to estimate the average clothing insulation value and metabolic heat rate. However, the site record forms were only answered by a student representative who recorded if any openings were closed or any air conditioning systems were working whilst the students were completing the questionnaires. A comparative analysis was performed on the results of the field studies in the classrooms. The results from the field measurements were compared with the results of the survey questionnaire.

Indoor RH %

Figure 4: Mean indoor temperature and relative humidity during the survey in classroom S.

4.2. Metabolic Rates and Clothing Insulation In addition to field measurements, personal parameters such as metabolic rate and clothing insulation should be assessed to predict the thermal comfort of the occupants. In this study, these two personal factors were estimated according to ASHRAE Standard 55 [7]. It gives a series of metabolic rates for typical tasks and clothing insulation values for typical ensembles. A clothing

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Classroom

Number of students

Metabolic heat rate MET

N S

23 22

1.0 1.0

Clothing insulation value (clo) 0.76 0.76

Comparing the results of the two classrooms, it can be seen that the mean value of clothing insulation and metabolic heat rate of the occupants in both classrooms were the same, which indicates that most of the students wore clothes with similar insulation values in the warm months of April and May whilst they were doing similar activities in the classrooms. 4.3. Thermal Responses Based on questionnaire survey results, thermal responses of two classrooms occupants have been analysed. Figure 5 shows the percentages of thermal sensation votes on the seven point ASHRAE scale for classroom N and S on the 4th May 2010. The questionnaires were filled out at 12:00 pm by 45 students in both classrooms. From figure 5 it can be seen that in classroom S 43% of the students felt neutral (comfortable) while answering the questionnaires. Comparatively, only 30% of the occupants in Classroom N felt neutral while 35% voted in the category 2 (slightly warm) of the ASHRAE scale, which is the highest percentage. Generally, 84.1% of the occupants in classroom S voted in the central three categories of the ASHRAE scale (slightly cool, neutral and slightly warm) but only 60.5% of students in classroom N voted in these three categories. According to ASHRAE Standard 55 [7], a vote inside the central three categories (-1, 0, 1) of the ASHRAE scale expresses satisfaction or acceptance and the results shows classroom S falls in to this category. Table 3 shows that the mean indoor temperatures in two classrooms were around 23.5 °C. However, relative humidity was 35.4% in classroom N and 28.8% in classroom S, although they have nearly the same number of occupants. The questionnaire results indicate that the windows and the door of classroom S were being kept open during

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Percentage of votes (%)

Table 4: Average metabolic rate and clothing value of students during lesson hours in schools.

teaching hours and the classroom is located on the southern side of the building. Classroom N is on the northern side of the building and the windows were kept open while the door was usually closed during the teaching hours, which results in a higher humidity level. A comparison of simultaneous votes on both the thermal sensation and preference scale on ASHRAE and the McIntyre scale has been performed and are shown in Figures 6 to 8. 50.00% 40.00% 30.00% 20.00% 10.00% 0.00%

-3

-2

-1

0

1

2

3

ASHRAE scale N S

Figure 5: Relative frequency of ASHREA thermal sensation votes on the 4th May 2010 in classrooms N and S.

The results of the thermal preference votes on the McIntyre preference scale shows that 31.1% of the occupants voted „No change‟ in classroom S and 55.3% preferred to be cooler. However, in classroom N, the majority of the students voted to be cooler and only 4.4% preferred no change and no one wanted to be warmer (Table 5). Table 5: Percentage of occupants votes on thermal preferences on 3 point McIntyre scale.

Classroom

Cooler

No change

Warmer

N S

95.6% 55.3%

4.4% 31.1%

0.0% 13.6%

Comparing the simultaneous votes on both the thermal sensation of the ASHRAE scale and thermal preference of the McIntyre scales show that in classroom N only 4.4% of the occupants voting “Neutral” (0) on the ASHRAE scale wanted “No change” on the McIntyre scale and 0% wanted to be warmer but 26.1% preferred to be cooler. On the other hand, in classroom S, 13.6% of the students voting “Neutral” (0) on ASHRAE scale, wanted “No change” and 22.7% preferred a cooler environment. However, 9.1% of the occupants in classroom S wanted warmer environment (Figures 6, 7, 8). Percentage preferring no cahnge (%)

section on the questionnaire was designed using checklists of clothing items which students usually wear in their school environment. Students wore school uniforms which were a combination of a T-shirt or sleeveless blouse, thin trousers, socks, shoes, head wear and a thin long sleeve shirt dress (manto). Students always wear a manto, trousers and head wear on top, as these are typical female school uniforms in Iran. However, they adjust their clothing under their uniform according to the heating or cooling seasons. Based on Heidari‟s studies [8], clothing insulation for head wear is usually 0.1clo in the heating season. Metabolic rate was assumed to be light office activities, with students seated and reading or writing 15 minutes prior to the survey. Table 4 shows the average metabolic rate and clothing insulation value of the occupants in the classrooms during the survey.

15.00% 10.00% 5.00% 0.00% -3

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Figure 6: Percentage preferring no change on ASHRAE scale votes on the 4th May 2010 in classroom N and S.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Percentage prefering to be warmer (%)

Figure 7 illustrates that in classroom N no one wanted to be warmer. In contrast, 13.5% of the occupants voting “Neutral” (0) and “Slightly cool” (-1) on ASHRAE scale preferred to be warmer during the survey.

Table 6: Percentage of occupants votes on their perception of relative humidity in classrooms during a survey.

10.00%

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Figure7: Percentage preferring to be warmer on ASHRAE scale votes on the 4th May 2010 in classroom N and S.

Figure 8 illustrates the percentage of thermal sensation votes on the ASHRAE scale voting to be cooler on the McIntyre scale in classrooms S and N. It can be seen that a large number of students in classroom N preferred to be cooler compared to classroom S. In classroom N, 30.4% of students who voted “Warm” (+2) on the ASHRAE thermal sensation scale wanted to be cooler and the same number of the occupants voting “Slightly warm” (+1) preferred to be cooler as well. Comparing the overall percentage of votes Figure 8 shows that 55.3% of the students wanted to be cooler in classroom S. In contrast, 95.6% of the occupants in classroom N wanted to be cooler in their thermal state, which is the majority of the students. Comparing simultaneous votes between thermal sensation votes on the ASHRAE scale and thermal preference votes on the McIntyre scale shows that neutral sensations are not always the preferred temperature. Although 84.1% of the occupant in classroom S voted inside the central three categories of the ASHRAE scale, which express satisfaction, and 43% voted “Neutral” (0), only 13.6% of the students voting “Neutral” on the ASHRAE scale voted “No change” on the McIntyre scale. Percentage prefering to be cooler (%)

Tables 6 and 7 present the percentage of the occupants‟ votes on their perception of relative humidity and airflow in the two classrooms on the 4th May 2010.

It can be seen that more than half of the occupants in classroom N felt dry although 77.7% of the students in classroom S felt just right in terms of relative humidity. Comparing the mean indoor relative humidity in the two classrooms (Table 3), it can be seen that while the average level of humidity in classroom N was higher than classroom S, students in classroom N felt drier than classroom S (Table 6). Table 7: Percentage of occupants votes on their perception of airflow in classrooms during a survey.

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Table 7 shows that 65% of the students in classroom N felt the airflow was still during the survey. However, 63.6% of the occupants in classroom S voted breezy during the survey. Overall, 21.7% in classroom N and 31.8% in classroom S answered just right to their perception of indoor airflow. As has been mentioned before, the door of classroom N is usually kept closed during the teaching hours but the door is open in classroom S so the majority of students in class N felt drier in their classrooms and voted “Still” on their perception of airflow. 4.4. Neutral Temperature Neutral temperature is the temperature at which people experience a sensation which is neither slightly warm nor slightly cool. At this temperature the mean votes of the subjects is neutral or at the middle point of the seven point ASHRAE scale. According to Heidari‟s studies [9], the indoor comfort neutral temperature (Tn) in the city of Tehran depends on the outdoor temperature (To) and can be found from:

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Figure 8: Percentage preferring to be cooler on ASHRAE scale votes on the 4th May 2010 in classroom N and S.

Tn =12.8+0.555To Based on this equation, the neutral temperature in the classrooms should be 23.1°C during the survey. Although the mean indoor temperature in both classrooms was around 23.5 °C, only 30% of students in classroom N and 43% in classroom S felt neutral and only 4.4% of them in classroom N and 13.6% in classroom S preferred no change on the ASHRAE scale. This shows that the neutral

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temperature for students aged between 15 and 18 is slightly different and should be a little lower than the one which was calculated by Heidari [9].

5. CONCLUSION Comparing simultaneous votes between thermal sensation votes on the ASHRAE scale and thermal preference votes on the McIntyre scale shows that neutral sensations are not always the preferred temperature. Although 84.1% of the occupants in classroom S voted inside the central three categories of the ASHRAE scale, 43% voted “Neutral” (0). Moreover, only 13.6% of the students voting “Neutral” on the ASHRAE scale voted “No change” on the McIntyre scale. Furthermore, on the 3 point McIntyre scale, 31.3% of the occupants voted “No change” in classroom S and 55.3% preferred to be cooler, although 13.6% preferred to be warmer. However, in classroom N, the majority of the students voted to be cooler but only 4.4% preferred no change and no one wanted to be warmer. The results show that in classroom N only 4.4% of the occupants voting “Neutral” preferred no change in their thermal state and 26.1% preferred to be cooler. On the other hand, in classroom S, 13.6% of the students voting “Neutral” wanted no change and 22.7% preferred to be cooler. These data show that neutral sensations are not always the preferred temperature. Comparing classroom N and S it can be seen that a large number of students in classroom N and S preferred to be cooler during April-May. In addition, more than half of the occupants in classroom N felt dry although 77.7% of the students in classroom S felt just right in terms of relative humidity. Comparing the mean indoor relative humidity in two classrooms it is found that while the average level of humidity in classroom N was higher than classroom S, students in classroom N felt drier than classroom S and it is likely that this was because the door of classroom N was usually being kept closed. In terms of airflow, 63.6% of the occupants in classroom S voted breezy but 65% of the students in classroom N felt the airflow inside their classroom was still and that this is the reason for feeling drier. Moreover, the mean indoor temperatures in the two classrooms were around 23.5 °C. However, relative humidity was 35.4% in classroom N and 28.8% in classroom S, although they have nearly the same number of occupants. The questionnaire results indicate that the windows and the door of classroom S were being kept open during teaching hours but in classroom N the windows were being kept open while the door was usually closed during the teaching hours which results in higher humidity levels. Based on Heidari‟s findings on neutral temperature in Tehran [9], the average neutral temperature in the school is 23.1°C and the average clothing value of the students was 0.76 clo. In addition, the average indoor temperature in classrooms during the field studies was 23.5°C but most of the occupants preferred to be cooler. To help students feel more comfortable in the classrooms, it is suggested that they wear clothes with lower clothing

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value during the spring, although this may be difficult from a cultural perspective. This study has indicated that even in the spring period many of the students in this school were not thermally comfort. This confirms the view that some guidelines needed to be developed to help in the design of sustainable schools in Iran.

6. REFERENCES [1] Hoffman, P. J. (2009). Making the change to sustainability: building green builds a better education. Techniques: Connecting Education and Careers. pp. 16-21. [2] CABE. (2010). Creating excellent primary schools. London: The Commission for Architecture and the Built Environment. [3] Nicol, F. & Humphrey, M. A. (2001). Adaptive thermal comfort and sustainable thermal standards for buildings. In: NCEUB. Moving Thermal Comfort Standards into the 21st Century. Windsor, UK, 5-8 April 2001. London: Network for Comfort and Energy Use in Buildings. [4] CBI. (2009). Annual report of Central Bank of Iran. Tehran: Central Bank of Iran. [5] Kasmai, M. (1993). Climatic classification of Iran (in Persian). Tehran: The Research Centre of Building and Housing, Ministry of Housing and Urban Development. [6] Climate Consultant 4. (2009). Temperature range in Tehran. Energy design tools [Online]. Available at: http://www.energy-design-tools.aud.ucla.edu/ [Accessed: 10 August 2010]. [7] ASHRAE. (2004). ASHRAE Standard 55. Thermal environmental conditions for human occupancy. Atlanta, GA: American Society of Heating, Refrigerating and Air-Conditioning Engineers [8] Heidari, S. (2000). Thermal comfort in Iranian courtyard housing. Unpublished PhD thesis, University of Sheffield, UK. [9] Heidari, S. (2009). Comfort temperature for Iranian people in the city of Tehran. Honar-HaYe-Ziba (Memari-va-Shahrsazi), 1(5), pp.5-14.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

A case study into the relation between temperature and work productivity in offices in the UK Laura JONES and Pieter DE W ILDE School of Architecture, Design and Environment, University of Plymouth, Plymouth, United Kingdom ABSTRACT: Research in the field of building performance often focuses on the potential to save energy and hence reduce building operation costs. However, from a business perspective, energy costs are normally only a fraction of personnel costs. As a consequence, many businesses are interested in the work productivity of their employees. Recent research from the USA and mainland Europe aims to link work productivity to temperature in order to allow building designers and facility managers to optimise operational conditions. However, it is yet to be demonstrated whether a generic relation between productivity and temperature can indeed be established, and whether this holds true across the globe. Therefore this presents a small case study carried out in the Southwest of the UK. Semi-structured interviews were conducted with occupants of all building phases with the aim of capturing the perception of the interviewees of the relation between temperature and productivity, as well as relevant contextual factors. The research supports the trends as identified by other publications but indicates o an optimum for the productivity curve that is about 1 C lower. Further research is needed to positively establish whether the UK optimum indeed differs from US and mainland Europe values. Keywords: temperature, work productivity, offices, case study

1. INTRODUCTION Building performance is no longer just linked to energy usage and operation costs. As stated by Mudarri [1], it is now seen as 'how well the building services the occupants in the space with comfortable and healthy conditions that maximise their performance and productivity’. While many different factors have an impact on productivity [2] and may lead to distraction/loss of concentration, one prime driver for maintaining thermal comfort conditions and ensuring productivity of office workers is the room temperature. Wheeler and Almeida [3] list as key affecting factors of productivity: personal space, climate control, daylight, office design, quiet and the facilities available. Furthermore length in job, confidence and practice in the task being carried out, mental and physical health also affect how productive individuals are. Sutherland and Cooper [4] state that ‘it is clear that health, well-being and quality of work life are associated with performance and productivity, and so understanding stress and pressure at work is vital if we wish to create a productive workplace.’ A number of studies have been conducted concerning the relationship between temperature and work performance. Heschong [5] concluded in general that as the temperature increases worker productivity decreases. Overall ‘a one degree Celsius increase in air temperature was associated with a 2 per cent drop in performance’. Fang et al [6] on the contrary believe that office work was not considerably affected by temperature. They did however find links to symptoms of Sick Building Syndrome and found that these were reduced at lower temperatures and humidity. They interpreted this as potentially improving productivity through the

subjection of office workers to lower temperature and humidity, but without providing evidence to support this relation. The seminal work on the relation between temperature and office work performance however is that of Seppänen, Fisk and Lei [7]. Their research utilised studies that measured performance against temperature in office-type work, using statistical analysis to establish the ‘percentage of performance change per degree increase in temperature'. Only studies that utilised objective measures of work performance were used, in order to develop a qualitative relationship. This was done with the aim of identifying cost benefits. Thus combining the results by Berglund (1990), Federspiel (2002), Johansson (1975), Link and Pepler (1970), Meese 1984), Niemelä (2001 and 2002), Pepler (1968) and Wyon (1996) they defined the normalised relationship demonstrated in figure 1.

Figure 1: Graph representing the normalised relation between temperature and relative work performance. (Image reproduced from Seppänen, Fisk and Lei [7]).

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The graph shows that as temperature increases so does performance - up to 21°C. When the temperature raises above 22°C performance decreases. Productivity was found to be at its peak around 22°C. This relationship shown does not support the theory of the arousal effect, which suggests that lower temperatures increase productivity. Note that not all of the data used was collected from an office environment, but that laboratory and classroom studies were also included. Call-centres accounted for a large proportion of the studies. This does not necessarily relate to general office work on a computer, which is the most common office activity. Furthermore, from a review of the literature regarding the internal environment and how many factors are interrelated, it becomes clear that many researchers believe that the relationship between temperature and productivity in office work can not be specifically isolated. Additionally, subjective testing methods can not be applied to all office work as not all tasks can be measured purely on the output quantity. Finally, the authors [7] state that some of the studies used only two temperatures for comparison. This therefore does not provide an effective data set; this difference in accuracy and size of data was aimed to be accounted for by weighting.

2. PROBLEM AND OBJECTIVE The majority of the studies relating to temperature and productivity have been conducted in the USA or mainland Europe. These geographic areas are known to have different climates as well as their own type of dominant HVAC systems The USA for has large areas with semi arid, desert, and humid subtropical climates, and many HVAC systems are air based. In Europe the climate is predominantly temperate continental, with a higher use of hydronic heating and cooling systems. Also, different countries have different working patterns and views on what constitutes good working conditions. Furthermore, work in the field of adaptive thermal comfort [8] indicates that perception of thermal comfort changes with outdoor conditions. This yields two interesting questions: (1) is there indeed one universal relationship between temperature and relative work performance, which is relatively stable across different climates around the globe? (2) what evidence is there that the relationship as percieved thus far applies to other locations and climates, like the temperate maritime climate of the UK? The research reported in this paper therefore aims to collect a dataset for the UK, concentrating on office work to ensure high continuity and to enable comparison with previous data. The main research question and relating subquestions are as follows: “What is the perceived relationship between temperature and work productivity in offices in the United Kingdom?”.

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The following sub-questions have also been investigated:  Are any trends present in office worker’s personal temperature comfort zones?  How do office workers perceive productivity and how do they feel it should be measured?  What are the main factors that affect productivity in offices?  Is there a relationship between perceived productivity and the age/construction of the buildings on the same site?

3. METHODOLOGY A case study was carried out on a Technology Campus in the Southwest of the United Kingdom. the site was selected on the basis of existing industry contacts, allowing good access to office workers at a commercial site. The Technology Park sits on a 25 acre site and has been under continuous development since its inception in 1995. At present the Park consists of four phases of construction that accommodate a community of businesses including its own management team. These four phases present a range of building types for this study, whereas location and climate are fully similar for each investigation. Figures 2 and 3 show images of phase three and four buildings.

Figure 2: Phase three case study building, located at a Technology Campus in the Southwest of the UK.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 3: Phase four case study building, located at a Technology Campus in the Southwest of the UK.

A series of semi-structured interviews were conducted at the Technology Park with the aim to produce largely qualitative data. This has been chosen as the most suitable data collection method for this research project because the objectives that need to be met require in depth information, views of the individuals and information on behaviour. Four individuals from each construction phase of the Park were selected, giving a total sample of sixteen office workers. The interview sample was selected by the Technology Park management as this would prove the least disruptive to the workplace. However, in setting up the sample they were asked to ensure that this would contain range of ages, a relatively even mix of male and female, and only people working in an office environment. This method used for selecting interviewees is convenience sampling which is a non-probability sampling, meaning that some people are more likely to be selected than others due to their relationship with the organisation selecting the participants. It is likely individuals were selected according to their availability on the day of the interviews, their job status, and other 'soft' factors, for instance making it likely that the more friendly and willing individuals will be chosen. This however should not have a large effect on the findings because the status and nature of the individual should not effect their perception of temperature and productivity. Also note that it is difficult however to remove all bias from any study and develop a truly representative sample [9]. The size of the sample was chosen as a trade-off between time, cost and precision. A size of sixteen meant that an even number of individuals could be selected from each building phase while not making it too intrusive on the organisation. The population at the Technology Park is relatively homogenous with the offices being occupied mainly by its own staff and small organisations. There will obviously be small differences between organisations however the basic setup is the same. This means a smaller sample could be taken from the total population. The sample was kept as large as possible to increase the likely precision of the data and reduce the sampling error; at the same time it was limited to sixteen as a reasonable number of interviews that could be conducted in one working day.

The questioning for the interviews was derived from the research questions of this study, providing a good structure to conduct all interviews in a similar pattern while allowing for the interviewees to give their own views and opinions. The interviews involved questions regarding perception of productivity, temperature and brief details of their job. The interviewees were also asked to sketch a graph similar to that of figure 1 to represent their perception of the relationship between temperature (°C) and productivity (%). The interviews were audio recorded and transcripts produced. In addition to the interview structure, a minimal set of data collection equipment was utilised. An instrument was brought along to record the temperature during the interviews, specifically an Extech RH520A humidity and temperature graphical data logger. The temperature in the room was stated during the interview to give the interviewee a gauge of how that specific temperature feels. The instrument used is believed to be reasonably accurate but was uncalibrated. Audio equipment was used to record the interviews. Full transcriptions were made of all interviews.

RESULTS As per research design, results from sixteen interviews conducted at the Technology Park were obtained. As described, the sample was obtained via convenience sampling, and thus may incorporate a slight bias on the data collected. The organisation would not see it beneficial to allow those individuals extremely unhappy with their workplace to be interviewed, especially regarding the topic of indoor environment as this will show a negative picture. It also means that it is unlikely that individuals in higher positions and those absent due to sickness would be included in the sample. The main result obtained from this research is a series of graphs that describe the interviewees perception of the relationship between temperature and work productivity. This material has been summarised by taking averages over the responses at each temperature of the data set, as well as splitting the data according to interviewee attributes like age group, gender, or building phase from which they operate. Some typical results are presented in figure 4 (average overall response), figure 5 (split between gender) and figure 6 (split according to building phase). The majority of the interviewees felt their productivity was affected by temperature with the exception of only one individual out of sixteen. In general they felt their productivity decreased when they were too hot or too cold, as demonstrated by figures 4, 5 and 6 . The overall optimum temperature for being productive suggested by this research is o o between 20 C and 22 C. The graphs that are split according to gender or building phase show distinct differences. It appears that females consider a higher temperature more productive than males. The trends for the four distinct building phases are harder to interpret, but they seem to indicate that there is a substantially

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It was evident from conducting the interviews that some of the individuals had not previously considered productivity in detail, or asked themselves what made them most productive. Several of the interviewees seemed very firm on their views whilst others found the question regarding productivity difficult to answer. The majority felt that productivity should be measured by the quality of the work produced. Others found they could not provide an answer for the best way to measure productivity or concluded that it would be through a mixture of quality and quantity. One interviewee stated that productivity is a ‘difficult concept to measure’ especially in their job of research. Another was more vague and stated ‘generally that over a period of time that you get everything done’. Other interviewees were able to identify that a measure of productivity should be job specific rather than applying the same testing to all tasks. Overall this demonstrates that there is a wide range of knowledge amongst office workers regarding productivity. Generally those in more creative jobs felt their work should be measured on the quality whereas those in more typical administrative jobs stated productivity should be measured on the quantity of the work they complete. The interviews conducted show that even in office based jobs there is still a wide range of tasks that are completed. This makes a measure for productivity very difficult to develop and generalise.

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different optimum for each phase. Interestingly there does not appear to be a trend where older phases require a higher temperature or vice versa, which might have been expected due to advances in technology and engineering capacities. However, there might be an issue with robustness of the optimal temperature: the older phases seem to be much more tolerant, in the sense that the gradient close to the optimum is less steep. A similar graph has been produced to study a split over age categories, but the results are inconclusive. It must be noted that the graphs produced are based on a small sample size only, and therefore must be interpreted with caution. Individual results vary widely. As an example, one interviewee suggested that the bandwidth for best productivity is o as narrow as only 2 C, whereas another allows for a o range as large as 12 C. The same goes for optimal temperatures, which in the results range from as low o o as 12 C to as high as 27 C. These and similar effects are likely to underlie the 'spikes' at the edges of the graphs.

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Some further salient points made during the interviews are the following:  Three interviewees had previously been located in an office in another phase at the Technology Park. All persons believe they have moved to a better thermal environment, and that this has raised their productivity.  One interviewee stated that a deeper consideration of the consequences of design decisions is needed, whereas the current focus seems to overemphasise energy efficiency. This supports the need for this type of research, as well as broader Post Occupancy Evaluation studies.  One interviewee experienced issues with noise from a metal roof in their previous office and now believes they are more productive in a newer office without this distraction. This reinforces the comment in literature that the temperatureperformance relationship must always be seen in a wider context.  The interviews have not identified any issues between job satisfaction and health or number of sick days. Most of the interviewees rated their job satisfaction high or relatively high and very few of them had over 1 day of absence in the last year. This could be accounted for due to the location and the ambience at the Technology Park, which is not located in the centre of the city and where there is a relaxed and friendly feel amongst workers. A few of the interviewees are self-employed which means their job satisfaction was very high due to enjoyment and flexibility of the job.



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One avenue for future research is crosscomparison of findings for different buildings in terms of optimal temperatures for productivity, but also in terms of the robustness of the optimum. Further research is needed to positively establish whether the UK optimum indeed differs from US and mainland Europe values. Due to the small sample size the work presented in this paper must be considered as a preliminary study in this area.

Overall one would expect the relationship between temperature and relative work performance to be subject to different contextual factors, like gender, age, and culture. This would lead to large uncertainties, and the relationship like depicted in figure 1 needing to incorporate a significant bandwith of uncertainty.

5. ACKNOWLEDGEMENTS The authors wish to thank Mr Derek Prickett, Associate Lecturer at the University of Plymouth, for establishing the link with the Technology Park, and all interviewees that participated in this project.

4. CONCLUSION AND DISCUSSION The results from the research, carried out by conducting semi-structured interviews with office workers at a Technology Park in the Southwest of the UK, lead to the following conclusions:  For offices in the UK a perceived relationship between temperature and work performance can be established that is very similar to that reported by the seminal work in the field [7]. However, the results suggest an optimum for the o productivity curve that is about 1 C lower.  As can be expected there are differences amongst the office workers concerning the temperature which they believe best for being productive. The general range identified varies o o between 18 C and 22 C.  Looking at the split over the genders, results indicate that the perceived relationship is similar; however females appear to be more productive at a higher temperature of 22°C, as opposed to a lower temperature of 20°C for males.  In terms of measuring work performance, people in more creative jobs felt their work should be measured on the quality whereas those in more typical administrative jobs stated productivity should be measured on the quantity of the work they complete.

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6. REFERENCES [1] D.H. Mudarri, ‘The economics of enhanced environmental services in buildings’, in D. Clements-Croome (ed.) Creating the productive workplace. 2nd edn. Oxon: Taylor & Francis, pp. 99-112 (2006) [2] G.R. Newsham, J.A Veitch and K.E. Charles, ‘Risk factors for dissatisfaction with the indoor environment in open-plan offices: an analysis of COPE field study data’, Indoor Air, 18 (4) pp. 271-282 (2008) [3] G. Wheeler and A. Almeida, ‘These four walls: the real British Office’, in Clements-Croome, D. (ed.) Creating the productive workplace. 2nd edn. Oxon: Taylor & Francis, pp. 357-377 (2006) [4] V.J. Sutherland and C.L Cooper, ‘Stress and the changing nature of work’, in Clements-Croome, D. (ed.) Creating the productive workplace. 2nd edn. Oxon: Taylor & Francis, pp. 81-96 (2006) [5] L. Heschong, ‘Windows and office worker performance: the SMUD Call Center and Desktop Studies’, in Clements-Croome, D. (ed.) Creating the productive workplace. 2nd edn. Oxon: Taylor & Francis, pp. 277-309 (2006) [6] L. Fang, D.P. Wyon, G. Clausen and P.O. Fanger, ‘Impact of indoor air temperature and humidity in an office on perceived air quality, SBS symptoms and performance’, Indoor Air, 14 (7), pp.74-81 (2004) [7] O. Seppänen, W.J. Fisk and Q.H. Lei, ‘Effect of temperature on task performance in office environment’. Berkeley: Lawrence Berkeley National Laboratory (2006) [8] F. Nicol and M. Humphreys, ‘Derivation of the adaptive equations for thermal comfort in freerunning buildings in European standard EN15251’, Building and Environment 45 (1), 1117 (2010) [9] A. Bryman, Social research methods. Oxford: Oxford University Press (2008)

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Fading Shades of Green Perceptions and Responses to Working in a Sustainable Office IDA G. MONFARED1, PROFESSOR STEVE SHARPLES2 1 2

School of Architecture, University of Sheffield, Sheffield, UK School of Architecture, University of Liverpool, Liverpool, UK

ABSTRACT: During a consolidation project the staff of the UK Border Agency (the Home Office) in Sheffield, UK, were moved from five conventional buildings to a complex of two new ones, Vulcan House, which were the first offices in the region to achieve a BREEAM Excellent rating for their sustainable design. However, environmental assessment methods like BREEAM often underestimate the important role of occupants on the building’s real performance. After a building becomes occupied the technical measures that once defined the building’s sustainability will transform into more cultural values which depend on occupant behaviour. The degree of occupant engagement with the sustainability values of a building not only affects the building’s performance, but can also reduce or enhance their perception of satisfaction with their environment. This research followed the experiences of 2000 staff of Vulcan House as a sustainable workplace through a longitudinal study (2008-2009) of perceptions and satisfaction. This study included interviews and repeated surveys. In the era when the climate change and environmental issues brought up the urgency to define a new notion of satisfaction, this paper tries to emphasise that the occupants’ attitudes are as important as technical measures in achieving buildings with lasting sustainability. Keywords: BRREAM, green offices, occupants’ perception, satisfaction, sustainability.

1. INTRODUCTION Since the negative impact of built environment on nature has been acknowledged, environmental assessment methods like BREEAM, LEED and Energy Star have been introduced to tackle this problem. These methods are increasingly promoted through global and national policies and their appeal is growing with the professionals in the built environment sector [1]. However, such methods are adopted in the early stages of a building life cycle (design and construction) while the building‟s real performance will start after it becomes occupied. Sustaining the building‟s performance in accordance with its „green‟ design intentions not only depends on its success to meet the technical design goals, but also on the behaviour of the building‟s end-users (the occupants). Therefore, the occupants understanding, expectations and perceptions of a „green‟ building can play an influential role on the building‟s real performance. The definition of a sustainable building from the occupants‟ point of view is quite a complex issue. In those cases were living or working in a „green‟ building is not the result of an individual‟s choice it becomes more complicated to clarify if the building‟s green identity remains a priority value from the occupant‟s perspective. This research addresses this matter, based on the evidence of a case study in Sheffield, UK. Vulcan House is a „BREEAM Excellent‟ rated building which is accommodating the staff of the UK Border Agency (UKBA) in Sheffield, whom were previously working in five conventional buildings. Through a longitudinal study this research

tried to identify and highlight the nature of the relationship between a „green‟ building and its occupants.

2. BACKGROUND The Building Research Establishment Environmental Assessment Method (BREEAM) was a pioneering method for assessing the environmental impact of buildings. It was introduced in 1998 in the UK by the Building Research Establishment and it has been continually upgraded and improved ever since. In BREEAM a building is evaluated in accordance with a series of categories and gains credits in return for providing evidence of the design‟s achievements in these categories. The main categories are: management, health and wellbeing, energy and transport, water, materials, land use and ecology, and pollution. The overall score will rank the building in one of six categories: unclassified, pass, good, very good, excellent and outstanding. The last category, „outstanding‟, was introduced in to the 2008 version of BREEAM to be given to those buildings that in addition to meeting the „excellent‟ rating also gained extra credits for innovation. The BREEAM credentials in some of the categories cannot change after the construction of a building is complete (e.g. land use) but some of the other categories will depend on how the occupants use the building (e.g. energy and transport). In practice, within these categories many interrelated goals should be fulfilled, and this adds further complexity to the building‟s sustainable performance. For example, pursuing energy conservation policies

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by a building management team could have an impact on the occupants‟ well-being and satisfaction. Occupant dissatisfaction with some environmental conditions might have to be addressed by the building management team which might, in turn, lead to the building‟s systems being altered, possibly with less commitment to maintaining the building‟s sustainability performance. Many studies have been carried out on occupant satisfaction and, in particular, the occupants‟ environmental comfort in green buildings [2] [3]. It has been shown that in terms of the overall score of some of the environmental aspects, such as the overall score of lighting conditions, green buildings received better ratings than their conventional counterparts. However, when these measures are divided into their subcategories, this difference is no longer clear cut. Unmanageable complexity, overheating problems during summer in passiveventilated buildings, and unsatisfactory noise conditions (as a result of adopting open-plan design strategies to conserve more energy) are some of the reported problems with green buildings [4]. Socio-psychologists believe comfort and satisfaction are not merely dependent on technically optimal conditions [5]. In some cases, despite environmental discomfort, the occupants were highly satisfied with their building as there were other influential elements involved. For example, there was a case where, despite the uncomfortable thermal conditions, occupants could relate to their organization‟s mission of having a „green building‟ [6] and it was actually the occupants‟ sense of pride that contributed to their overall satisfaction. It has recently been argued that to achieve more success in sustainable design the notion of comfort has to change and move beyond its conventional definition [7]. Another study has discussed how user performance criteria can be incorporated into building sustainability rating tools [8]. But, in a more conceptual term, what is occupant perception of a „green‟ building? In particular, when working in a „green office building‟ is a given requirement and not a voluntary choice, how do the occupants interact with this situation? What is the impact of working in a BREEEAM „Excellent‟ office building on the occupants‟ satisfaction with the building and their expectations? This research tries to answer these questions based on the experience of staff in an award winning „green‟ office building. Although it has the empirical limitations of a case study, it highlights the importance of occupants‟ attitude towards the concept of sustainability to achieving a successful sustainable design.

the highest existing standards of sustainable design, and therefore became the first BREEAM Excellent office buildings in Sheffield. These buildings have similar and simple lay-outs, except that Steel is relatively larger and it benefits from a light-well in the middle of its cubical shape. Iron is smaller and, instead of the light-well, there are meeting rooms, a small stair-well, and some storage space in the middle of the building. According to BREEAM for design and construction Steel achieved a score of 79.77 credits and Iron 73.54 credits. Some of the sustainability related elements of design are: heat reclaim and circulation systems, prefabrication of plant and minimal packaging during construction phase, HFC free cooling and heating plant, and grey and rain water recycling systems for toilets. During a consolidation project the staff who were previously working in five conventional buildings (Figure 3, a-e) moved to Vulcan House, where they were given user-guides and introductory tours.

Figure 1: Vulcan House, Steel

3. CASE STUDY & METHODOLOGY Coinciding with the UK Government policy on reducing carbon emission in public buildings, Vulcan House was commissioned by the Home Office in Sheffield. It is a complex of two buildings, named Steel (Figure 1) and Iron (Figure 2), which are connected by a bridge at the second floor. The new buildings were designed and built in accordance with

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Figure 2: Vulcan House, Iron

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The old and new buildings‟ dates of build and sizes can be summarised as follow: Previous buildings:  Aspect Court: Late 1960s, refurbished in 2001, 2 office –5,388 m , 7 floors, steel and concrete construction  Milton House: Early 1980s, refurbished in early 2 2000, open plan office –7,283 m  Foundry House: Opened in 2002, office –2,107 2 m  Exchange Brewery: Period former brewery building 1852, converted into office 2 accommodation in 1990s - 2,335 m  Moorfoot: Opened in 1981, open plan office – 2 20,130 m

with facility management, likes/dislikes of place of desk and staff facilities, trends of recycling, travel plan, and overall satisfaction. The 2009 questionnaire contained further details on occupants‟ experiences regarding sustainability almost two years after the building was occupied. Interviews with focus groups were conducted, with a particular interest on sustainability, to gain further insight of staff understanding and expectation from a green office place, their priorities, and if they found their new workplace in accordance to their expectations. Also, the ways of which these issues could be communicated in a more efficient way between the management team and staff were discussed.

Vulcan House: 2  Steel: 2008, open plan office –11,100 m . 2  Iron: 2008, open plan office –7,200 m .

a. Aspect Court

b. Milton House

d. Exchange Brewery

c. Foundry House

e. Moorfoot

Figure 3: Previous buildings staff had worked in before moving to Vulcan House

Questionnaires were distributed first in 2008 and then again in 2009 (both during November with two week time intervals), which received 928 responses (50% of 2000 members) and 950 (53% of the 1800 members) respectively. The questionnaires contained various sections to cover environmental aspects (in accordance with known similar methods [9]), distance from windows, issues with lack of control over environmental conditions, satisfaction

4. SOME RESULTS An initial analysis of the relationships between different variables measured in this study is presented in this paper, and the scores of some variables and their differences between groups of staff moving from their five previous buildings are presented. Also, the interaction between occupants and some features which were related to the building‟s green design are discussed.

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Although this research started after staff moved to the new buildings, their record of which previous building they have moved from was kept. It was interesting to study the influence of new workplace in various aspects of staff experiences and expectations and to see if there was a significant difference between these responses. 4.1. Overall satisfaction with the building Overall satisfaction was measured on a seven scale variable, where 1 = Very dissatisfied and 7 = Very satisfied. In 2008, the score of overall satisfaction between groups of staff from previous buildings was significantly different (F (5,918) = 3.43, p < 0.05, one-way between groups Anova). Here, the greatest difference was between the scores of staff from Aspect Court (mean value = 3.88) and Exchange Brewery (mean value = 4.77). But by 2009 there was no significant difference between the overall satisfaction scores. That means that almost two years after moving in to the new building, the distribution of satisfaction scores between staff from different previous buildings became homogeneous. It was also interesting that when staff were asked if their quality of their work has decreased or increased since moving to Vulcan House, no significance was found between the scores of staff from the different previous buildings. 4.2. Satisfaction with the facility management In the case of Vulcan House, there were not many opportunities for the occupants to control their environmental conditions directly. Instead, any modification of these conditions was controlled by the Building Management System (BMS) and a Facility Management (FM) team. The occupants could report any problems with their environmental conditions to a help-desk, after which the FM team could tune the conditions for that particular location with the accuracy of an area as specific as each desk. In practice, this system found management difficulties. The pattern of location of problematic areas reported to the help-desk by the occupants did not match the BMS records of such problems reported by sensors. This issue raised a general sense of disappointment with the building‟s facility management and control conditions amongst occupants. But this dissatisfaction was shared evenly between staff from different previous buildings. No statistical significance was found between the scores of satisfaction/dissatisfaction (5 scale variable) with FM between groups of staff from different previous workplaces both in the 2008 and 2009 results. Although a central control system was also used in the previous buildings the occupants in those buildings had more opportunity to modify their environmental conditions – for example, with openable windows. In the case of Vulcan House, the reminder of conservative energy policies by the FM when occupants reported minor problems caused further frustration rather than any sympathy with the building‟s green identity.

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4.3. The occupants’ perception of the building’s sustainability Staff were asked about their perception of the “sustainability” or “greenness” of the two Vulcan House buildings, Steel and Iron, separately. No significance was found between the votes of staff from previous buildings in both cases. Also, they were asked if they believed that the building‟s sustainable design has reduced or enhanced their level of comfort, but no significance was found in their votes. In general, Steel scored slightly better than Iron, with 5% voting the building to be very sustainable in comparison with 4% for Iron (in a 7 scale variable, 1 = Very unsustainable, 7 = Very sustainable). The in-depth discussion with focus groups during interviews showed that the majority agreed that Vulcan House deserved its green credentials. However, in choosing between a conventional and a green building, their higher priority was comfort rather than considerations of if the building was environmental friendly or not. In response to the question of did they find Vulcan House in accordance with their expectation of a sustainable building, there was a variation of attitudes. When staff were asked if they preferred the buildings to have special „green‟ features like solar panels and wind-turbines, they did not support the idea. While they believed that Vulcan House deserved the credits, they were not quite sure if it represented a particularly „sustainable‟ building. In general, they agreed that the environmental issues should be considered as a value, but they could not relate these issues to their workplace and to their job pressure. Their demanding and difficult daily jobs did not leave much space to be particular engaged with these sustainability subjects. From the members of staff who were interviewed, those who were more involved in the primarily stages of the design and move (consolidation team) were more satisfied with the building than those who felt their comfort was compromised for the sake of the building‟s „sustainable‟ design. The ways in which knowledge about the building‟s achievements could be transferred and shared proved to be complicated. The building‟s user-guides, which was given to staff prior to their move, were found to be too technical and nothing in the interest of occupants was highlighted. Although there was a general need for further knowledge and information, the efficient means of communication were hard to define and „time‟ had to be reserved to meet the job needs. For those, who were less satisfied with the building, there was also a sense of scepticism about the buildings‟ sustainability. Overall the staff believed that as their main priority was meeting the job targets then any other issues were overshadowed and they believed they had no choice but to „get on with‟ any given conditions. 4.4. Features and facilities As has been mentioned, Vulcan House does not have an especially „green‟ appearance and features e.g. „green‟ energy generators. From the range of features and facilities provided in the building, the two features of a garden at the bottom of the light-

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

well and a green roof-garden represented the building‟s „greenness‟ more than any others features. But in terms of their benefits for staff, they scored quite low in comparison with other facilities, such as the restaurant. In 2008, 70% found a little or no benefit in the light-well garden and the score was 50% for the roof-garden. These scores were 73% and 60% respectively in 2009. In comments made about these features, staff said they would have preferred it if the light-well was used as the storage space instead. The rate of using the provided recycling facilities has improved from 53% in 2008 to 59% in 2009. In 2009, 27% said the provision of these facilities has improved, 62% said it has not changed and 10% said it became worse. 4.5. Travel plan, least successful policy Although the building has gained 100% BREEAM credits for its travel plans, this feature was not very successful in practice. The location of the new building has good access to public transport. However, this was true for the previous buildings as well. Using „green‟ modes of transport was highly promoted since staff moved to Vulcan House and many incentives, such as subsidised bus tickets and higher rates for car parks, were introduced. However, in 2008, 79% said their mode of transport had not changed since moving, while this rate was 71% in 2009. In 2008 32% used their own cars, 26% used buses and 2% rode on bicycles. In 2009, these scores remained almost the same, with 37% using their own cars, 27% using buses and 2% using their bikes. In response to the question of had the bicycle parking and shower facilities affected the staff choice for mode of transport, 89% in 2008 and 90% in 2009 said the new facilities did not encourage them to walk, run or cycle to work. In the comments made about this issue some of the staff mentioned that the reason for them for using their own cars instead of walking was their sense of insecurity, especially in the evenings around the building‟s neighbourhood. However, this opinion was not shared by everyone. As the results show, it was more a matter of „habit‟ rather than any other preferences.

5. DISCUSSION & CONCLUSIONS During this research the experience of staff in a new green workplace has been compared with their previous experiences with conventional office buildings. Within the early months after moving to the new buildings, the occupants‟ overall satisfaction with the building varied between the groups of staff from different previous buildings. However, this variation did not remain statistically significant after two years. Also, the between group votes for occupants‟ perception of building‟s greenness, the influence of sustainable design on their comfort and any improvement in their performance since moving to the new buildings, were not significantly different. There were not many opportunities for any direct control over environmental conditions for the occupants. Here, the results relating to environmental conditions and controls were in

general agreement with previous studies from other researchers; the lack of control was reported as an element of dissatisfaction. But this problem became amplified on the occasion of environmental discomfort [10]. The only opportunities to pass the knowledge relating to the building‟s „green‟ identity to the occupants were the provided user-guides and introductory tours. But in the case of this organization the highly demanding job did not leave any time and interest to be spared by the occupants for these matters. The main priority for the occupants was their comfort, for which the reputation of the new buildings (being BREEAM Excellent) had set that target relatively high. Those who felt that their comfort was compromised for the sake of sustainability and the building‟s „green‟ identity were most dissatisfied with the building. Those who tolerated any inconvenience were the same people who were most satisfied with the building. However, the environmental conditions for them were not necessarily much better than the rest of the occupants The HVAC and lighting systems used in Vulcan House were quite sophisticated and achieved high levels of BREEAM credentials. But that sophistication, combined with the sense of disappointment felt by some of the occupants regarding FM performance, did not lead to a satisfactory balance. It should be mentioned that some compromises were made by the manufacturers and engineers during the construction phase and this is probably common throughout the construction industry. However, these problems proved to be difficult to rectify after occupation. In general, fully centralised control systems are difficult to be managed, and providing satisfactory environmental conditions that met the needs of 2000 people proved to be a demanding task. One of the measures that showed that the technical design implementations were not always guaranteed to be successful in reality was the travel plan predictions. Whereas according to BREEAM providing bicycle parking and reducing parking space is a necessity for a sustainable design, their success depends on a wide range of measures to be considered, i.e. an occupant‟s culture and habits. In the case of Vulcan House, despite providing incentives and promotions, these features were not very successful. It can be concluded that building environmental assessment methods like BREEAM will merely provide a platform to build-upon and not a comprehensive solution for sustainability. These methods will not guarantee a thoroughly successful sustainable building for long periods of time unless they consider occupant influences on the building‟s performance. Sustainability is not a technical feature which can be implemented in a building design once and for ever, but it is a flowing measure which needs a coherent and close relationship between different parties involved in a building‟s performance. Maintaining a sustainable building is not always a straightforward and easy task. In the case of green office buildings what is crucial is the agreement and effective collaboration between staff and building

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managers, and the engagement and dedication of both of these groups to the building‟s green identity. If this fragile relationship breaks then the „greenness‟ of the building can eventually fade.

6. ACKNOWLEDGEMENTS The authors would like to thank Peter Szypko and Loveday Herridge, members of the Home Office sustainability management team in Vulcan House, for their great collaboration with this research for two years. This study also owes much to Ian Ward and Edward Murphy, who provided the opportunity for this study to take place.

7. REFERENCES [1] Davies, R. (2005), “Green Value-Green Buildings, Growing Assets”, Royal Institute of Chartered Surveyors, London. [2] Bordass, W., Leaman, A. (2007), “Are users more tolerant of 'green' buildings?" Building Research and Information, 35 (6): 662-673. [3] Leaman, A., Thomas, L., Vendenberg, M. (2007), “'Green buildings: what Australian building users are saying”, EcoLibrium (November): 22-30. [4] Abbaszadeh, S., Zagreus, L., Leher, D., Huizenga, C. (2006), “Occupants satisfaction with indoor environmental quality in green buildings”, Proceeding of Healthy Buildings, Lisbon, III, 365-370. [5] Chappells, H., Shove, E. (2005), “Debating the future of comfort: environmental sustainability, energy consumption and the indoor environment”, Building Research and Information, 33 (1), 32-40. [6] Heerwagen, J., Zagreus, L. (2005), “The Human Factors of Sustainable Building Design: Postoccupancy Evaluation of the Philip Merrill Environmental Center”, Summary Report, University of California, Berkeley. [7] Cole, R. J., Robinson, J., Brown, Z., O'Shea, M. (2008), “Re-contextualizing the notion of comfort”, Building Research & Information, 36 (4), 323-336. [8] Baird, G. (2009), “Incorporating user performance criteria into building sustainability rating tools (BSRTs) for buildings in operation”, Sustainability, 1, 1069-1086. [9] "The Occupants Indoor Environmental Quality Survey”, www.cbe.berkeley.edu/research /briefssurvey.htm. (2010). [10] Baird, G., Lechat, S. (2009), “Users‟ perception of personal control of environmental conditions in sustainable buildings”, Architectural Sciences Review, 52 (2), 108-116.

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Definition of occupant behaviour patterns with respect to ventilation: An approach to the summer thermal comfort of apartments from the real estate market in Santiago de Chile FELIPE ENCINAS PINO1 1

Architecture et Climat, Université catholique de Louvain, Louvain-la-Neuve, Belgium

ABSTRACT: It has been demonstrated that there is a strong relationship between occupant behaviour and the thermal performance of dwellings. At the same time, some aspects of this behaviour, especially with respect to natural ventilation, constitute some of the most important sources of uncertainty in the field of building energy simulations. A survey about perception of thermal comfort and occupant behaviour was carried out in Santiago de Chile during December 2009 and January 2010 in a pilot case study corresponding to an apartment building. This paper proposes a methodology based on the systematic application of multivariate statistical techniques which were applied to the collected data of the survey. The results of the analyses show that daytime ventilation is not strongly correlated to the perception of thermal comfort, probably because it is mainly oriented to hygienic purposes. On the contrary, nigh ventilation appears as a very significant predictor for the same dependent variable. The final objective of these models corresponds to the definition of behaviour profiles which can be used as hard data to make calculations of energy performance of dwellings more accurate and reliable. Keywords: summer thermal comfort, occupant behaviour profiles, building energy simulation

1. INTRODUCTION It has been demonstrated that there is a strong relationship between occupant behaviour and thermal performance of dwellings. Indeed, according to Macdonald et al. (1999), some variables related to occupant behaviour constitute some of the main sources of uncertainty in the field of energy building simulations [1]. In that sense, depending on the variability of aspects such as scheduled internal gains or natural ventilation (by means of manually operable windows), a wide range of variation in the energy consumption of dwellings may be expected. Uncertainty and sensibility analyses frequently deal with this situation, since they can generate a great range of forecast values based on the distribution of the input variables. For example, in the case of the physical properties of building materials, this variability has been studied and may be obtained from references as Clarke et al (1999) [2]. However, Hyun et al (2008) explain that the widely varying occupant influences - especially related to operable windows - have not been directly measured or investigated [3]. At the same time, most of the building energy simulation programs are deterministic, rather than probabilistic and consequently their results frequently are not expressed in probabilistic terms. Additionally, a considerable difference between the standard values of ventilation used for simulations and the ventilation patterns in real occupied dwellings may be expected. Therefore, if the aim is to represent a wide range of cases (instead of a singular case study), it is necessary to characterize the occupant behaviour in terms of profiles to be used as input data in energy building simulations.

Due to the link between occupant behaviour and energy consumption, it is important to define it from the interaction with the control mechanisms of windows during both day and night, and also establishing the reasons for that specific behaviour, as is recommended by the IEA (1988) [4]. Andersen et al (2009) indicate that most of the energy building simulation programs provide possibilities of regulation of control systems (such as opening / closing windows), but there are no guidelines for how the simulated environment should be managed by the software. Consequently, the definition of a set of standard behaviour patterns –based on the quantification of real inhabitants’ behaviour- would significantly improve the validity of the outcomes of the simulations [5]. In this context, the obtained behaviour patterns represent a first approach in the process to obtain a more real thermal behaviour, since this information needs to be combined with meteorological data by means of building performance simulations. The aim of these numerical simulations is to find a relationship between occupant behaviour patterns, ventilation rates and summer thermal comfort. The final objective of these models corresponds to the definition of behaviour scenarios which can be used as hard data to make calculations of energy performance of dwellings more accurate and reliable.

2. METHODOLOGY Due to the importance of the occupant behaviour and ventilation on the thermal behaviour of apartments it is necessary to collect data about these aspects based on real sources. Nonetheless, due to the lack of references in the national state of art, a survey to obtain this information is required.

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The pilot case study corresponds to the Edificio Don José, located in the Santiago borough, city of Santiago. This is an apartment building, constructed in 1993-1994, with 22 floors and 8 apartments per floor. The building is situated in an urban environment, near to the city centre. The survey was applied to 91 randomly selected apartments in two summer months (December 2009 and January 2010). The sample size corresponds, consequently, to 91 cases over a population of 166 apartments. The margin of error and the confidence level are 6% and 90%, respectively. It is important to remember that the scope of the survey is related to the indoor environment and occupant behaviour in apartments of Santiago de Chile based on a pilot case study. Due to this, the survey frame was considered as appropriate. A most ambitious experience may be proposed as further research. In that case, the population of the survey can be extended to several apartment buildings in Santiago de Chile. 2.1. Statistical Methods Factorial analysis is a multivariate analysis technique that it is used to reduce the dimensions of a large set of observed variables. The new obtained variables received the name of factors, defined as a lineal combination of variables. Also, the method allows the detection of subjacent dimensions that belongs to a correlation matrix. According to the procedure for extracting factors, it is possible to distinguish the “Factor Analysis” and the “Principal Component Analysis (PCA). Since the objective of this study is to obtain a reduction of a large set of information contained in certain questions of the survey and perform further analysis with this information, the procedure of PCA was selected. Table 1  presents all the variables that were considered to carry out the PCA. These questions were selected in order to represent the different aspects related to the perception of thermal comfort, natural ventilation and strategies and systems that affect the thermal behaviour of apartments.

3. RESULTS Table 2 presents the rotated component loadings, which give information about the strength of the relationships between the variables and components. These loadings are expressed in terms of correlation coefficients (with values between 0 and 1). According to the Kaiser’s criterion (Eigen values >1.0), 4 components were extracted, which account for the

73.2% of variance. At the same time, according to Hair et al. (2005), communalities below 0.5 should be probably dismissed, as they do not have enough explanation for their variances [6]. In the table, it can be observed that all variables present communalities that can explain at least the half of their own variance and therefore should be considered in the model. In order to improve the interpretation of the model, a procedure to rotate the factorial axis of the solution was applied. The objective of the VARIMAX technique is to maximize the components variance. For this solution, coefficient values above 0.60 were considered as significant. As the significance of a factorial loading depends on the size of the sample, this reference value was taken for a sample of 85 observations. The sign of the coefficients indicates if they are positively or negatively correlated with respect to their corresponding component. In consequence, the four defined components of the rotated matrix can be interpreted as: C1: Daytime ventilation, both in winter and summer (Q16 & Q20), which are positively correlated C2: Perception of favourable thermal comfort in winter (Q6) and avoiding the use of heating appliances (since it is negatively correlated) (Q27). Both situations can be related to a good thermal behaviour since occupants declare they generally do not feel cold during winter and at the same time they minimize the use of heating. This phenomenon can be explained through the specific environmental conditions of their apartments (e.g. favourable orientation) or due to particular reasons. C3: Perception of unfavourable thermal comfort in summer (Q10) and use of night ventilation (Q24), which are positively correlated. This situation can be represented for occupants that describe their apartments in summer as “warm” or “hot” and due to this, open windows during night time. C4: Presence of solar protection (Q13), which is positively correlated Table 2: Rotated component matrix by means of VARIMAX Variables Q6 Q10 Q13 Q16 Q20 Q24 Q27

Components C1

C2

C3

C4

0.02 -0.22 0.01 0.76 0.86 0.14 0.05

0.85 0.15 0.00 0.20 -0.16 -0.06 -0.71

-0.02 0.65 0.11 -0.26 0.14 0.84 -0.14

0.19 0.13 0.90 0.24 -0.16 -0.03 0.44

Communalities 0.76 0.52 0.82 0.75 0.81 0.74 0.72

Significant variables per each component

Table 1: Considered variables for the Principal Component Analysis (PCA) Subject Perception of thermal comfort

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Question Q6 Q10

Variable Thermal sensation in the apartment during winter Thermal sensation in the apartment during summer

Ventilation

Q16 Q20 Q24

Daytime ventilation in winter Daytime ventilation in summer Use of night ventilation in summer

Strategies and systems

Q13 Q27

Presence of external solar protection Use of heating systems in winter

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

“Factor scores” are a sub-product of the PCA application. Also, they represent a useful result in order to carry out other multivariate analysis techniques. Figure 1 presents perceptual maps per orientation, based on the factor scores obtained previously by means of the PCA. In this case, perceptual maps are the graphical expression of the associations between two components that compose the solution and where their observations are clustered by a specific criterion. Figure 1 shows the perceptual map of C2 vs. C3 in terms of “comfortable” and “not comfortable” for both winter and summer, respectively. According to this, north orientation was characterised as comfortable in both seasons, while south oriented apartments are associated with a favourable and unfavourable thermal behaviour in summer and winter, respectively. For both orientations, these results can be considered as expected.

N

SE NE

0,0 -1,0

SW NW

0,0

1,0 W

Comfortable (winter)

Not comfortable (winter)

S

Comfortable (summer) 1,0

E

-1,0 Not comfortable (summer) Figure 1: Perceptual map of C2 vs. C3 (horizontal and vertical axis, respectively

4. DISCUSSION 4.1. Application of a discrete choice model to identify relationships between variables The logistic regression analysis is a mathematical model with the aim of predicting the behaviour of a dependent variable as function of one or more independent variables. The objective of this model is to predict the probability of occurrence of an event with a dependent variable that assumes the value of 1 when the event occurs and zero in the absence of the event. The prediction is made from a group of independent variables with explanatory capability with respect to the dependent variable The model that predicts the dependent dichotomic variable Y from multivariate independent variables Xk in probabilistic terms corresponds to:

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where e is the base of natural logarithms and being an irrational number, their first digits are 2.71828.

With the aim of predicting the level of incidence of the variables that determines the perception of thermal comfort, one question of the survey (Q41) was expressed as: “Do you feel comfortable in your apartment in terms of thermal comfort?” The two possible answers were “yes” or “no”, which convert this variable in dichotomical. Therefore, the probability of occurrence of the answer “yes” (Y=1) in the question 41, can be expressed through the following logistic regression function:

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� 

�

�� ���� � �� ��  � �� ��  � �� ��  � �� ��  �

     

where C1, C2, C3 and C4 are the factor scores that were obtained through the PCA, b1, b2, b3 and b4 are the coefficients for these variables and a is a coefficient of the model. According to Hair et al. (2005), it is recommendable to consider factor scores for configuring a logistic regression model where the sample is the same and the independent variables are orthogonal [6]. Table 3 presents the obtained coefficients for the logistic regression model proposed for the Q41 of the survey. These coefficients were obtained by means of the maximum verisimilitude procedure using statistical software. According to the obtained solution, coefficient b1 is not significantly different from 0, from a statistical point of view. This means that component C1 is not significant to predict the probability of occurrence of Q41. This situation can be understood from the idea that daytime ventilation of C1 (which includes both winter and summer) is mainly oriented to a hygienic purpose, instead of cooling. This observation is highly consistent with the study by Andersen et al. (2009), which proposes that the thermal sensation of the occupants is not a statistically significant predictor of the windows opening behaviour [5]. The reason for this may be explained by the idea that if a window is opened because the occupants feel too warm, it will probably stay open until they start to feel cold. Because of this, occupants with open windows may have a thermal sensation anywhere between warm and cold [5]. Another important aspect regarding the obtained coefficients of Table 3 is the sign of b3. As can be observed, this sign is negative, which means that while the value of C3 is higher, the probability that Q41 can be answered as “yes” is lower. In other words, if the thermal sensation of the occupants during summer is hot, there are more possibilities that the people feel uncomfortable in their apartments Table 3: Obtained coefficients from the multivariate logistic regression

a

1.97

Standard error 0.48

4.09

4.38E-05

b1

0.30

0.30

1.01

3.13E-01

b2

0.62

0.35

1.77

7.68E-02

b3

-0.90

0.45

-2.00

4.59E-02

b4

0.97

0.49

1.99

4.64E-02

Coefficients

Z value

Pr (>|z|)

Not significantly different from zero

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Considering the obtained coefficients, the logistic regression applied can be expressed as:

������ �  

�

�� ������� ����� ��  � ���� ��  � ���� ��  ����� ��  �

             

In this equation, it can be observed that the most important aspects related to the overall perception of thermal comfort in the apartment (Q41) are the presence of solar protection (C4), the perception of summer thermal comfort and night ventilation (both contained in C3). Newly, these weightings can be considered as expected since the survey was taken during summer. In that sense, it is not surprising that with the presence of solar protection, a not excessive indoor temperature, and night ventilation most of the people considered their apartment as comfortable (Y=1, considering that the survey was carried out in summer). 4.2. Definition of ventilation scenarios by means of a cluster analysis

The seminal study carried out by Punj & Stewart (1983) established that cluster analysis is a statistical method for classification. Indeed, the objective of this can be defined as the identification of a group of entities that share certain common characteristics [7]. For the purposes of this research, the hierarchical technique was chosen as clustering method. This classifies by stages through a process that follows the structure of a tree and where each stage of the process generates a new branch. In this context, the selection of the factor scores of the PCA as variables for the procedure is justified since it allows to correct the interdependencies. Also, the nonequivalence of metrics between the original variables of the survey suggests the use of this procedure. In the range of solutions proposed for the model, the alternative of 4 clusters was selected as the most representative, since their groups are consistent and well defined. Therefore, four profiles (P1, P2, P3 and P4) were characterized for both winter and summer from the number of hours of ventilation per day. Figure 1 presents the number of ventilation hours per day in summer. As can be observed, P2, P3 and P4 present a similar behaviour with respect to the different times of the day. On the contrary, P1 presents a very particular behaviour, since the highest level of ventilation occurs at noon. Occupants associated with this profile probably are not aware of the thermal implications of their behavioural habits related to ventilation, since windows are opened in the hottest time of a summer day in Santiago. Then, when temperature decreases most of the windows are closed. This situation is consistent with the declared reasons for opening or closing windows in summer collected by means of the survey. Figure 3 presents the results for two questions (Q22 & Q23) of the survey with respect to these issues. It can be observed that the occupants that belong to P1 may not use natural ventilation as passive cooling technique, since windows operation is mainly limited to close them. On the contrary, 75% of the people of P4 open the windows of their apartments due to the overheating, which indicates a particular concern with respect to thermal comfort.

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P1

P2

P3

P4

3 2 1 0 Morning

Noon

Afternoon Afternoon - night

Night

Figure 2: Number of ventilation hours per day in summer Q22: " I open the windows of my apartment in summer due to it is hot" Q23: "I close the windows of my apartment in summer to avoid the overheating of rooms"" 100% 80% 60% 40% 20% 0% P1

P2

P3

P4

Figure 3: Results for two questions of the survey with respect to the reasons for opening and closing windows in summer per profiles

These ventilation profiles, proposed from the collected data of the survey represented the first step to obtain hard data which might be directly applied to thermal simulations. After that, building performance simulations were done using TAS software [8]. The four profiles were applied to a floor layout of the same building selected for the survey, using also the collected information of the survey to define internal gains of the different apartments (between 105 and 115 Wh/m²/day, including occupation, lighting and equipments). Hourly meteorological data for the year 1989 in Santiago de Chile were taken from ASHRAE (2001) [9], which were also compared and validated with respect to the monthly values of the NCh 10792008 national standard (based on a period of 30 years of meteorological observations). The aim of these numerical simulations is to find a relationship between occupant behaviour patterns, ventilation rates and thermal behaviour. The proposed profiles, at the moment, just represent an intention of ventilation, but they need to be characterized in terms of their impact on the thermal comfort of the apartments. Figure 4 presents the overheating degree hours per orientation according to the adaptive model of EN 15251 [10] for P1 and P4 profiles. These results are consistent with regard to the perception of summer thermal comfort of the Figure 1 and show that when night ventilation is being applied, P4 appears as a more efficient regime to reduce overheating. This suggests that the thermal performance of night ventilation also depends on the windows operation during daytime.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 5 presents curves of temperature and air change rate in two summer days for the main bedroom of the western apartment for also P1 and P4 profiles. Indoor temperatures in both profiles show the favourable impact of the night ventilation strategy to reduce the risk of overheating. This also can also be explained considering the climatic conditions of Santiago de Chile (due to the difference between outdoor and indoor temperatures that it is possible to reach during night-time). At the same time, the obtained ventilation rates differ substantively between both profiles, as consequence of their windows operation regimes. This situation suggests that windows operation may be correlated with the ventilation rate, which could be determined by means of an uncertainty and sensibility analysis. Figure 6 shows the Pearson’s correlation coefficient of different parameters with respect to the air change rate in the main bedroom per orientation. All the variables (windows operation, ∆T: difference between indoor and outdoor temperature, wind direction and wind speed) appear as sensitive variables with respect to the ventilation rate, which modify their relative level of importance as function of the higher exposition to opened windows (as can be observed through the comparison between P1 and P4). Wind direction and wind speeds also show important differences in each profile with respect to orientation, presenting considerable higher correlations in the exposed orientations (S, SW, W and NW).

   Without night cooling With night cooling   The centre point of each bubble is the extent of Note:  overeating measured in degree hours (mean value for the   different spaces). The area of the bubble represents the   deviation for the distribution of values including the standard same   rooms. 8000   P1   6000     4000       2000    0   N NE E SE S SW W NW 8000   P4     6000     4000     2000    0 N

NE

E

SE S

SW W

NW

Figure 4: Bubble plots for overheating degree hours according to the adaptive comfort model of the EN 15251 [10] for P1 and P4 profiles under different conditions

Outdoor temperature [°C]   Summer comfort upper limit [°C]   Summer comfort lower limit [°C]   Indoor temperature [°C]   Indoor temperature applying night cooling [°C] Air change rate [h-1]   Air change rate applying night cooling [h-1]     P1   30       20     10     0     P4   30       20     10     0   Figure 5: Curves of temperature [°C] and air change rate -1 [h ] in two summer days for the main bedroom of the W apartment for both P1 and P4. Upper and lower limits of adaptive summer comfort calculated from EN 15251 [10]

  ∆T* Wind speed   Wind direction Windows operation   = Difference between indoor and outdoor temperature [°C] * ∆T°     P1 1,00     0,50       0,00   N NE E SE S SW W NW   -0,50     P4 1,00     0,50       0,00   N NE E SE S SW W NW   -0,50     Figure 6: Pearson correlation coefficient for different parameters from P1 and P4 profiles with respect to air change rate [h-1] in the main bedroom per orientation

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Finally, Figure 7 shows that orientation has the higher correlation with respect to the obtained overheating degree hours in comparison to other design parameters. Facade area/conditioned area ratio, glazing ratio and layout are the second, third and fourth variables, respectively, in order of sensitivity. However, when night cooling is considered in the assessment, the relative importance of these parameters can significantly change, which should be considered by designers.

  Orientation Layout   Glazing ratio FA/CA*  * FA/CA = Facade area / conditioned area ratio     Without night cooling 1,00     0,50       0,00   P1 P2 P3   -0,50       With night cooling 1,00       0,50     0,00   P1 P2 P3     -0,50  

6. ACKNOWLEDGEMENTS This study was carried out as a part of a PHD Thesis at the Architecture et Climat research centre from the Université catholique de Louvain in Belgium. The study is funded by the Bourse de coopération au développement from the same university. The author would like to thank to Pilar San Martin Vila and Carlos Aguirre Núñez for their support for the development of the questionnaire survey and the statistical models, respectively.

7. REFERENCES P4

P4

Figure 7: Pearson correlation coefficient for different design parameters under different conditions of night ventilation with respect to the mean value of overheating degree hours

5. CONCLUSIONS The explanatory analysis carried out through the PCA and the logistic regression established the relative importance of the different variables that determine the perception of thermal comfort of an apartment in Santiago de Chile. Through these techniques, the role of ventilation in the thermal sensation of the occupants was identified, associating daytime ventilation with hygienic purposes, while night ventilation appeared directly related to passive cooling. These observations are very useful to understand the perception of occupants about the different aspects related to the thermal comfort of apartments in Santiago de Chile. Nonetheless, if one of the declared objectives of the survey is to provide information for energy building simulations, it is absolutely necessary to obtain hard data from the collected information. This was carried out by means of a cluster analysis. As was explained, the definition of ventilation regimes is one of the main sources of uncertainly in an energy building simulation, mainly

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due to its dependence on the inhabitant’s behaviour (by means of windows opening). However, if these ventilation regimes are defined based on a more real approach, the results of the simulation are more representative and reliable and in consequence, uncertainty decreases.

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

[1] Macdonald, IA, Clarke, JA & Strachan, PA 1999, ‘Assessing uncertainties in building simulation’, Proceedings of Building Simulation 1999, Paper B-21, Kyoto, Japan. [2] Clarke, J, Yaneske, P & Pinney, A 1999, ‘The harmonisation of thermal properties of building materials’, Report CR59/90 of the Building Research Establishment, Watford, UK. [3] Hyun, S, Park, C & Augenbroe, G 2008, ‘Analysis of uncertainty in natural ventilation predictions of high-rise apartment buildings’, Building Services Engineering Research and Technology, vol. 29, no. 4, pp. 311-326. [4] IEA 1988, Inhabitant Behaviour with Respect to Ventilation - a Summary Report of IEA Annex VIII, International Energy Agency, Energy Conservation in Buildings and Community Systems Programme, AIVC - Air Infiltration and Ventilation Centre. [5] Andersen, RV, Toftum, J, Andersen, KK, & Olesen, BW 2009, ‘Survey of occupant behaviour and control of indoor environment in Danish dwellings’, Energy and Buildings, vol. 41, pp.11-16. [6] Hair, J, Anderson, R, Tatham, R, & Black, W 2005, Análisis Multivariante (Quinta edición), Pearson Educación, S.A., Madrid. [7] Punj, G & Stewart, DW 1983, ‘Cluster Analysis in marketing research: review and suggestions for application’, Journal of Marketing Research, vol. 20, no.2, pp.134-138 [8] EDSL 2010, EDSL TAS, . [9] ASHRAE 2001, IWEC International Weather for Energy Calculations, ASHRAE, Atlanta [10] CEN 2007, EN15251:2007 Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics, European Committee for Standardization, Brussels

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Thermal Comfort Temperature in Outdoors for Extreme Warm Dry Climate Gonzalo BOJÓRQUEZ-MORALES1, Gabriel GÓMEZ-AZPEITIA2, Rafael GARCÍA-CUETO3, Pavel RUIZ-TORRES4, Aníbal LUNA-LEÓN1 1

Faculty of Architecture and Design, Autonomic University of Baja California, Mexicali, Mexico 2 Faculty of Architecture and Design, University of Colima, Colima, Mexico 3 Institute of Engineering, Autonomic University of Baja California, Mexicali, Mexico 4 Faculty of Architecture, Autonomic University of Chiapas, Tuxtla Gutierrez, Mexico

ABSTRACT: In order to establish bases for right decisions in urban design, it is necessary to estimate the effect of different meteorological variables on the comfort sensation of people carrying out outdoor activities. Thus, outdoor thermal comfort must be one of the essential characteristics of urban environment quality. The objective of the research presented in this paper was to determine the effect of dry bulb temperature on the thermal sensation of users of outdoor recreational areas in extreme warm dry climate. A correlation field study with adaptive approach was developed in four periods in the city of Mexicali, Baja California, Mexico. Simultaneously to the comfort votes of people were registered data of dry bulb temperature, gray globe temperature, relative 2 humidity and wind speed. A total of 2124 observations were collected for passive activity level (0 to 75 W/m ). In warm and cold periods, the extreme conditions determine characteristics of asymmetric climates. Opposite, in the periods of transition, the conditions are those characteristic of symmetric climates. Consequently, the collected data was analyzed with the called method "Averages by Interval of Thermal Sensation (AITS)”, in order of avoid the bias generated for the conventional method in asymmetric climates. The adaptation phenomenon is evident in the changes of neutral temperatures (Tn) values estimated for each study period. Keywords: Thermal comfort, Outdoors spaces, Neutral temperature, Passive activity, Extreme warm dry climate

1. INTRODUCTION Knowing the temperature of thermal comfort outdoors, provides the basis for making a correct decision in the design of spaces, which can lead to users being in thermal comfort for the development of their activities. Outdoors spaces are those that are created to define nature and create an external environment for a specific purpose, they are not covered and are defined by two plans: floors and walls [1]. The thermal human comfort is defined in ISO 7730 [2] such as “that mental condition that express satisfaction with the thermal environment”; that also can be defined according to Nikolopoulou [3] such as “the psycho-physiological satisfaction of the human with respect to the climatic conditions of the surroundings”. The need for research on thermal sensations perceived outdoors has been observed in events like the Olympics Games and world fairs [4] as well as projects such as Rediscovering the Urban Realm and Open Spaces [3], the contributions of these works have applications in projects of tourism, recreational areas or areas of exhibitions. The time stay in outdoors is less than indoors, due to the thermal adaptation process, this implies that the application of a thermal comfort model developed for indoors has a tendency to overestimate the actual sensation of the outdoors users. This discrepancy is greater in low temperatures compared to high temperatures. In outdoors, it is not adequate to use a prediction

model, due to the variability of thermal environments, outdoor conditions and time stay; while the implementation of the adaptation method to the being the result of an assessment field is best suited to outdoors conditions [5]. The objective of this article is to show the estimation of temperatures of thermal comfort for the users of outdoors in recreative center, in warm, cold and periods of transition in a desert climate. The study was developed with the approach adaptative of the thermal comfort, by means of the application of surveys with the scale of sensations of ISO 10551 [6], and measures of dry bulb temperature. Later, a statistical analysis of stratum of thermal sensation was done by stratus and a linear regression was performed to obtain the temperatures and thermal comfort ranges for passive activity level (0 to 75 2 W/m ). The warm and cold periods presented asymmetric climate behaviour, whereas the periods of transition were symmetrical. The neutral temperature values obtained in the periods studied, demonstrate the theory of adaptation applied to the outdoors, as the temperatures of thermal comfort changed as the meteorological conditions are modified.

2. METHOD There were used the parameters of the approach adaptative: data source, type of habitat, reactions to analyse, type of receiver of the information and level of analysis. For the selection of the approach of this

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. study also other similar works were reviewed [3, 5, 7]. The study was realized in Mexicali, Baja California, a city of the northwest of Mexico, that is situated at a latitude of 32°39'54" N, longitude of 115°27'21" W, and an altitude of four meters above sea level. The climate is warm and extremely dry, with an average maximum temperature of 42ºC (with extreme maximum of 52ºC) and an average minimum temperature of 8°C (with extreme minimum of -6ºC) [8]. In figure 1, appears Mexicali’s location.

MEXICALI

North Norte UNITED STATES OF AMERICA

ESTADOS UNIDOS DE AMERICA BAJA CALIFORNIA

MÉXICO

Figure 1: Location of Mexicali, Baja California, Mexico.

The passive activity level was studied (0 to 75 2 W/m ); the metabolic relation of energy consumption was established based on Fanger [9] and Mondelo et al., [10]. The passive type activities were: walking, observing, talking and playing with children in a peaceful manner. The levels of average clothing (Clo) of subjects studied by period are presented in table 2. Table 2: Clo average of people for period of study.

Period of de study Warm

Clo average of people 0.27 Clo

Cold

0.84 Clo

Periods of transition

0.61 Clo

The selection of meteorological variables to measure was based on the effect of the same in the perceived thermal sensation, as well as in the analysis of some cases of study on thermal comfort in indoors and outdoors [3, 4, 11] and the norms ISO 7730 [2] and ISO 7726 [12]. The measurements of variables were: dry bulb temperature, relative humidity, wind speed and gray globe temperature. Also a thermal stress equipment was utilized. (See figure 3). As the methodology as the equipment met the majority of the requirements of the norm ISO 7726 [12], reason why the generated data are of Class II [13].

The research was carried out in the YOUTH RECREATION CENTER 2000, where sports, outdoor exercises and other living activities are practiced. This park presents green areas, corridors of concrete and land, sports fields of basketball, soccer, baseball and track to trot, as some administration buildings, gymnasium and area of special courses (See figure 2).

Figure 3: Monitor of thermal stress.

Figure 2: Youth Recreation Center 2000

A correlation study of dry bulb temperature with the thermal sensation perceived was developed. The periods studied are presented in table 1. The schedules of application of survey were from 07:00 to 21.30. Table 1: Periods of study of fieldworks.

548

Period type Warm

Periods of study July 25 to August 10, 2008

Cold

2nd to the 20 of January, 2009

Transition periods

1 to the 13 of April 2008 October 27 to November 9, 2008 th th 13 to the 26 of April 2009

th

st

th

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

The questionnaire was designed based in ISO 10551 [6] and a manual of application of survey and manual of instruments was developed. A sample with a reliability of 95% and precision of the estimators of 5% was designed. A total of 2122 observations were realized, 389 in the warm period, 449 in cold period and 1284 in the periods of transition. The study subjects were men and women between 12 and 65 years of age, did not include individuals with irregular biological conditions like chronic diseases or pregnancy. Some images of application of surveys appear in figure 4. The data analysis was carried out with the method of Averages by Interval of Thermal Sensation (AITS) [14], which was developed with base in the proposal of Nicol [15] for “asymmetric” climates. A scheme of the mentioned method appears in figure 5.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 4: Application of surveys.

The fundamental difference of the AITS with the conventional method is that before obtaining the line of regression that characterizes the studied sample, groups or stratum are determined of the same to calculate the value average and the standard deviation (SD) of each of them.

ASWERS OF THERMAL SENSATION 7

Hot

6

Warm

5

Slightly warm

4

Neutral

3

Slightly cool

2

Cool

1

Cold

3. RESULTS The results for period of study and a comparative analysis is done and presented in this section. It is necessary mention that with base in data dispersión, it is considered that the major thermal adaptation was had when there was a minor dispersion of the obtained answers.

Analysis of thermal sensation scale -2SD

-1SD

Mean

+1SD

+2SD

UNIVARIABLE LINEAR REGRESSION (From of obtained values)

-2SD

The purpose of this procedure is to determine the average value of temperature of all the responses of each level of perceived thermal sensation. In that manner it was calculated the average temperature of the individuals that reported feeling comfort, but also those who expressed other thermal sensations. Based on the above, the data collected in the field study was processed separately according to each of the seven categories of comfort response of ISO 10551 [6]. The values were determined for each of them the average and standard deviation of the temperatures registered for each collected answer. When the number of answers for a certain group was not sufficient to obtain reliable results, the procedure was omitted and the category was eliminated. Once this data was obtained, ranges of distribution were established for each category of response. It was made from the average value of corresponding temperature (TnMean) and the addition of ±1SD, the procedure is repeated and is added ±2SD to the TnMean. Finally a linear regression was made with the values that were obtained, to determine the corresponding lines to the extensive limits of the range defined by TnMean ±2SD, and the reduced limits defined by TnMean ±1SD. Also the same was done with the values of TnMean. In that way graphs are obtained for every period of the study. The intersection of each one of the lines of regression with the ordinate four (that represents the thermal sensation of comfort) determines the value of the neutral temperature according to AITS method, as well as, the limit values of the ranges of thermal comfort.

-1SD TnMean +1SD +2SD Reduced range Extensive range

Figure 5: Temperature of thermal comfort with the method of averages by interval of thermal sensation.

Thus, the regression is not done with all the pairs of data of the sample, but only with the average values and ranges are determined by the addition and subtraction of one or two times the standard deviation of the sample.

3.1. Warm period There were no cold sensations. A tendency of data towards the values of -2SD in the thermal scale sensations of “neutral”, “slightly warm” and “hot” was observed. With regard to values of +2SD, the tendency was only observed in the scale of sensations of “hot”. This was because at this level of thermal sensation a gain of heat in the thermal balance of persons was recorded since temperatures of thermal environment were higher at 37ºC (average of body temperature) (See figure 6). The regression lines had a tendency to be converged with respect to an average line of regression; accordingly, there was an increased thermal sensation of hot which represented a greater adaptation to warm conditions rather than to cold, as well as, a variability in the conditions of thermal and psychological adaptation of the persons. The neutral temperature was symmetrical with respect to the ranges of extensive and reduced

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Thermal sensation

thermal comfort. This is due to the low level of internal energy generated by persons studied, due

to passive activity, and its thermodynamic interchange with thermal environment.

7 6 5 Neutral value (comfort)

4

Extensive range 14.7ºC

3 Reduced range 7.4ºC

2 -2SD

1 5

Mean

-1SD

15

25

+1SD

35

+2SD

45

Dry bulb temperature (°C)

Tn-2SD Tn-1SD TnMean Tn+1SD Tn+2SD 27.4°C

31.1°C

34.8°C

38.5°C

42.1°C

Figure 6: Neutral temperature and ranges of thermal comfort for passive activit in warm period.

3.2. Cold period

Thermal sensation

It was noted that in addition to the sensations of cold, the feeling of "slightly warm" was presented, the above was due to the internal temperature and metabolic activity levels of clothing (See figure 7). Also a tendency of convergence of the lines of regression was observed towards the line of 7

regression average accordingly the thermal sensation of cold increased, which indicated a better adaptation to these conditions of temperature for this period. The neutral temperature was symmetrical with respect to the ranges of extensive and reduced thermal comfort.

-2SD -1SD

Mean

+1SD

+2SD

6 5 Neutral value (comfort)

4

Extensive range 11.8ºC

3 Reduced range 5.9ºC

2 1 5

15

25

35

45

Dry bulb temperature (°C)

Tn-2SD Tn-1SD TnMean Tn+1SD Tn+2SD 13.8 °C 16.6 °C 19.6 °C 22.5 °C 25.6°C Figure 7: Neutral temperature and ranges of thermal comfort for passive activit in cold period.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. 3.3. Periods of transition

differences between the levels of adaptation for each scale of sensation were observed. A greater variability appeared as temperature increased, the previous indicated a lower degree of adaptation to high temperatures in the studied period, which agrees with the theory of adaptation of Humpreys and Nicol [16] (See figure 8).

Thermal sensation

In the thermal sensation of “warm”, a greater dispersion of the data was observed, with respect to another thermal sensations, the previous represented a lower level of adaptation of the persons from study to hot sensations. Significant 7

-2SD

-1SD

Mean

+1SD

+2SD

6

5 Neutral value (comfort)

4

Extensive range 11.8ºC

3 Reduced range 5.9ºC

2 1 5

15

25

35 45 Dry bulb temperature (°C)

Tn-2SD Tn-1SD TnMean Tn+1SD Tn+2SD 19.2°C

22.7°C 26.1°C 29.5°C 32.9°C

Figure 8: Neutral temperature and ranges of thermal comfort for passive activit in periods of transition.

3.4. Comparative analysis A significant variation in the neutral temperature of each one of the studied periods was observed, the previous was due to the process of adaptation of the persons with base in the conditions of the thermal environment (See table 3). Table 3: Neutral values and ranges of thermal comfort for studied period.

the variation between extreme climatic periods (warm to cold) was of 15.5°C. With regard to the ranges of thermal comfort, the variations were between two and three degrees from one period to another, which confirmed the acclimatization phenomenon. The values of the determination coefficient (R²), in the three periods of study, had values between 0.9804 and 0.9999, which is why the amount of variation in “y” is explained in significant form by the straight line of regression of the analyzed data.

Parameters

Warm period

Cold period

Periods of transition

DBTn+2SD

42.2°C

26.4°C

33.2°C

4. CONCLUSIONS

DBTn+1SD

38.5°C

22.9°C

29.7°C

DBTnMean

34.8°C

19.3°C

26.3°C

DBTn-1SD

31.1°C

15.7°C

22.8°C

Based on the obtained results the following conclusions can be established: In the periods of warmth and cold, there were extreme conditions and characteristic of asymmetric climate, while in the periods of transition conditions of a tempered climate of symmetrical type were observed. The temperature of thermal comfort presented a significant variation between a period of study and another one. The adaptation phenomenon was observed clearly in the exchanges of value of the Tn for every period of study. In the warm period a better adaptation to the conditions of heat was observed, whereas in the period of cold the best adaptation was to the cold

DBTn-2SD

27.4°C

12.2°C

19.4°C

Extensive range

14.7°C

11.8°C

13.7°C

Reduced range 2

R (MRL)

7.4°C

5.9°C

6.8°C

0.9999

0.9806

0.9804

DBTn: Dry Bulb Temperature neutral, SD: Standard deviation, R2 (MRL): Coefficient of determination of Mean Regression Line.

The variation between the periods of warmth and of transition was of 8.5°C, whereas the period of cold and the one of transition was of 7°C, however

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. conditions. In the periods of transition the best adaptation of the study subjects was to the cold conditions, without registering thermal sensations of “hot”. Based on the variation of amplitude of the extensive and reduced ranges, in general a better adaptation was observed to the conditions of cold, due to experience and expectation, from one period to another. The study serves as support in the decision making of design of exterior spaces in desert climate, since it allows consideration of the conditions of thermal comfort of the users, in three different climatic periods for the same level of activity.

[5] [6]

[7]

[8]

5. ACKNOWLEDGMENTS To all the collaborators in the work field, capturing and analysing data. Projects “Thermal comfort and saving of energy in the economic house in Mexico: dry and humid warm climate regions”, CONAFOVI 2004-01-20 and “Economic house in Mexicali: thermal comfort and saving of energy” UABC. Autonomic University of Baja California and University of Colima. To Ms. Alicia Ching and José Luis Cadena for all the support in the realization of this document.

[9]

[10]

[11]

6. REFERENCES [1] Ashihara, Y. (1982) El diseño de espacios exteriores. Barcelona: Gustavo Gili. [2] International Organization for Standardization. (2005). ISO 7730:2005 (E) Ergonomics of the thermal enviroment – analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria. Ginebra: Autor. [3] Nikolopoulou, M. (2004). Designing open space in the urban environment: a bioclimatic approach. Attiki: Center for renewable energy sources. [4] Pickup, J. and de Dear, R. (2000). An Outdoor Thermal Comfort Index (OUT_SET*) - Part I The Model and its Assumptions. In Biometeorology and Urban Climatology at the Turn of the Millennium. WCASP 50: WMO/TD No.1026. Edited by R.J. de Dear, J.D. Kalma,

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[12]

[13] [14]

[15] [16]

T.R.Oke and A. Auliciems. (WMO: Geneva). pp.279-283. Höppe, P. (2002). Different aspects of assessing indoor and outdoor thermal comfort. Energy and Buildings, 34, 661-665. International Organization for Standardization. (1995). ISO 10551:1995 (E) Ergonomics of thermal enviroment – assessment of the influence of the thermal environment using subjective judgement scales. Ginebra: Autor. Givoni, B; Noguchi, M; Saaroni, H; Pochter, O; Yaacov, Y; Feller, N. and Becker, S. (2003). Outdoor comfort research issues. Energy and buildings, 35, 77-86. Luna, A., Velázquez, N., Gallegos, R. y Bojórquez G. (2008). Aire acondicionado solar para conjunto de viviendas en Mexicali, B.C. México. Revista “Información tecnológica” 2008, vol.19, no.1, p.45-56. ISSN 0718-0764. Fanger P.O. (1986). Thermal environmenthuman requirements. The environmentalist. Volume 6, Number 4, 275-278. Springer Netherlands. Mondelo, P; Gregori, E; Comas, S; Castejón E. y Bartolomé E. (2001). Ergonomía 2: Confort y estrés térmico.(3ra. Edición). Barcelona: Universitat Politècnica Catalunya. Dear de, R; Brager, G. and Cooper, D. (1998). Developing an adaptive model of thermal comfort and preferentes. (Final Report on RP884). ASHRAE and Macquarie Research Ltd. International Organization for Standardization. (1998). ISO 7726:1998 (E) Ergonomics of the thermal enviroment – instruments for measuring physical quantities. Ginebra: Autor. Brager, G. and Dear de, R. (1998). Thermal adaptation in the buil enviroment: a literature review. Energy and Buildings, 27, 83-96. Gómez-Azpeitia G. Ruiz P. Bojórquez G. y Romero R. (2007). Monitoreo de condiciones de confort térmico. Reporte técnico CONAFOVI. 2004-01-20. Colima. Nicol, F. (1993) Thermal comfort “A handbook for field studies toward an adaptive model". London, University of East London. Humphreys, M. and Nicol, F. (2002). The validity of ISO-PMV for predicting comfort votes in every-day thermal environments. Energy and Buildings, 34, 667-684.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Thermal comfort in hospital environments LÉA Y. DOBBERT1, DEMÓSTENES F. SILVA FILHO1, CRISTIANE DACANAL2, CLEIDE A.M. SILVA2 1

2

Superior School of Agriculture Luiz de Queiroz, University of São Paulo, Piracicaba, Brazil School of Civil Engineering, Architecture and Urban Planning, University of Campinas, Campinas, Brazil

ABSTRACT: The important point to be covered and assessed here is the effort that hospitals face when the environment is considered and this issue depends on a number of factors such as thermal comfort and light among other functional aspects, such as equipment availability, safety, accessibility and user mobility. The existence of green areas or gardens at hospitals have a positive influence on the environmental comfort, especially when related to thermal sensation and satisfaction, as the microclimate is gradually changed by the vegetation. This study aims at focusing on the thermal comfort evaluation of users at Santa Casa hospital in Valinhos, SP (Brazil), also provides subsidies for landscaping projects in hospitals. The internal environments examined differ from the developed function and the contact that the users have with the gardens. The methodology consists at the measurement of internal environmental conditions and climatic variables and the simultaneous application of a questionnaire for evaluating the sensation and thermal preference, along with 228 hospital employees. The Predicted Mean Vote (PMV) and Predicted Percentage Dissatisfied (PPD), proposed by Fanger (1970) have been calculated in this paper. The comparison between the actual condition of comfort declared by respondents and the predicted votes, has exposed differences about these results significantly, as the percentage for the “satisfied” is in fact superior to that obtained by PMV. The comparison between environments in contact or not with the vegetation, has shown similarity between the values but has no significant difference on the results (p-value <0.05). Keywords: thermal comfort, hospital environments, microclimate

1. INTRODUCTION What should be emphasized most is the fact that open spaces can provide great improvement in the quality of life in a hospital environment when properly treated. The green spaces or gardens in hospitals play an important role in order to promote a social contact among patients, staff and other users. Furthermore, the contact with the gardens not only contributes to the restoration of the mental health status in patients, but reduces the stress and improves the thermal comfort, encouraging its use [1]. Scientific studies regarding the positive human influence from spaces with vegetation are presented by Kaplan (2001) [2] remarking the importance of a view through the window due to an increasing sense of feeling well. In another study, Kaplan (1993) [3] points out the benefits from the contact with nature in the workplace. Ulrich (1984, 1991, 2002) [4]-[5]-[6], Marcus & Barnes (1999) [7] and Zeisel (2007) [8] reported through conducted surveys mainly at hospitals, about the reduction of stress due to the contact with the nature. The works of Taylor (2001) [9], Fjeld (2002) [10], Grahn & Stigsdotter (2003) [11], Hansmann (2007) [12], Hartig et.al. (1997) [13] and Hartig (2007) [14], have shown positive responses concerning human contact with vegetation and landscapes in hospitals, schools and urban areas, recognizing the healthy influence of plants and stating that the effects are very important to people. As concerns the urban scale, few studies have been developed with the objective of observing the influence of vegetation on microclimate, thermal comfort and quality of open spaces. [15]-[16]. What

can be noticed, in warm climate regions is the existence of vegetation in open spaces, the design and appropriate furniture favoring the human permanence and intensifying the performance of the population’s activities [17]-[18]. Thus, it is highly recommended that the growing of trees and shrub species, as far as it’s known, provide shading is a major factor really responsible for the thermal comfort sensation in open spaces. In addition to cutting solar radiation down, plants have the ability to modify the microclimate, increasing humidity and decreasing the air temperature [19]. The natural characteristics of the trees, provide shade, improve the air quality and provide also an aesthetic harmony. The existence of vegetation in open spaces has an important role in establishing the relationship between man and nature, ensuring them best quality of life [20]. Something relevant to be considered at this point is the hospital setting; the thermal satisfaction of patients in recovery should be an important factor in recovering health. It is also important that patients and staff notice positively the physical aspects of this environment. The interaction of patients with the hospital green areas stimulates the development of activities for inmates and promotes the social interaction [1], thus the landscaping can be a key to the quality of the hospital design. Furthermore, the direct view or the visual contact with the gardens can influence the sense of well being not only to the inmates but also to the staff and other users. In this context, Vasconcelos (2004) [21] has found, in a survey which was conducted in three hospitals, the importance of promoting contact with the outside to increase the sense of well being and psychological comfort of its users. The patients

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2. METHODOLOGY

Services Street

North

Hospitalization

Kitchen Garden

Garden

Hospitalization Garden

Surgery room Pediatrics

Maternity

interviewed have reported their preference for environments containing visual pleasant colors, vegetation, ventilation and natural lighting. It was also emphasized in this study the benefit brought by the external environment to patients due to sensory stimulus caused by natural elements. A major aspect about the same issue is that under the ideal working conditions, the thermal discomfort of the environment is essential to cause the psychological “malaise”, the decrease in production capacity, the physical exhaustion and other disturbances [22]. The Brazilian Federation of Hospitals determines that for a comfortable situation in such environments, the temperature should be 24 ºC. The Norm number 17 of the Labor Ministry, however, determines the ambient temperature around 20 to 23 °C, air velocity up to 0.75 m / s and relative humidity below 40% for workplaces with intellectual activities and requiring constant attention [23]. Something relevant to be considered at this point is the fact that under these considerations, this study aims at evaluating the thermal comfort of workers in hospitals, based on ISO 7730 (1995) [24] and in questionnaires to evaluate the thermal sensation. Specific objectives were to compare the thermal comfort, predicted and related by the staff whose work environment has or not windows overlooking the gardens of the evaluated hospital.

Hospitalization Garden

Administration

ER

Garden

Garden Acess

Figure 1: Buildings and gardens of the hospital Irmandade Santa Casa de Valinhos.

(a)

(b)

Figure 2: (a) Garden with more shadow; (b) Garden with less shadow in the Irmandade Santa Casa de Valinhos, SP - Brazil.

2.1. CaseStudy Located in São Paulo, Hospital Santa Casa de Valinhos, lays at 22º 57' 47.90”S latitude and 47 ° 00'39.95''W longitude, at an altitude of 660m, in Valinhos city, Sao Paulo, Brazil, was the object of this project and study. The climate, according Köppen-Geiger classification, is Cwa that has warm and rainy summer, mild and dry winter. Having 5,704.44 square meters in its building area, predominantly one-pavement buildings, which allows the natural lighting and ventilation (Figure 1). Gardens are enclosed by buildings, adding 7,852.00 square meters and also different vegetation - with or without trees. The green diversity in the gardens (Figure 2) changes the level of shading and microclimate conditions, which may influence the microclimate and thermal comfort in the indoor environments. Due to the location of some rooms in the hospital, some wards, although across the gardens, have no direct eye contact with the green spaces or gardens (Figure 3).

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(a) (b) Figure 3: (a) environment without view to the garden ; (b) environment with view to the garden. Local: Hospital Irmandade Santa Casa de Valinhos.

2.2. Measurement of internal environmental conditions and climatic variables Of major importance is the fact that the environmental conditions and climatic variables monitoring and the questionnaires application for the assessment of sensation and thermal preference were conducted simultaneously during the months of November - December 2009 and January 2010, during two different periods of the day: 9:00-10:00h, 13:00-18:00h. The air temperature (°C), relative humidity (%) and wind speed (m s-1) with the aid of thermoanemometer and digital anemometer, positioned at 1.5m tall, were monitored. All measurements were made internally to working environments, divided into spaces with or without windows facing the gardens.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

2.3. Real thermal comfort (ASV) and calculated thermal comfort (PMV e PPD) For the evaluation of predicted thermal comfort, this work was based on the ISO 7730 (International Organization for Standardization) [24], which shows the thermal sensation predicting method and non comfort degree for people not exposed to moderate thermal environments, and also specifies Thermal acceptable comfort conditions. The PMV index (Predicted Mean Vote) represents the average vote of people regarding to thermal sensation [25], calculated from personal variables (metabolic energy and thermal resistance) and environmental variables (temperature and relative air humidity, wind speed and mean radiant temperature). The calculation of the PMV and PPD (Predicted Percentage of Dissatisfied) was made by using the software Conforto 2.02 [26]. For the evaluation of the real thermal sensation actual sensation vote (ASV) - 228 hospital staff were interviewed in their work environment. The employees were divided into two groups - one with a view to the gardens (78 respondents) and the other group did not have a view to the gardens (150 respondents).

3. RESULTS 3.1. Measurement of internal environmental conditions and climatic variables The average of the microclimatic variables (temperature, relative humidity and wind speed) in hospital settings, with or without windows overlooking the gardens, shows similarities between the two groups (Table 1). Table 1: Comparison of air relative humidity (RH) and air temperature (T) between environments with and without gardens contact.

opening windows to the gardens Yes No

RH (%)

T (oC)

68.8 (σ=6.3) 58.5 (σ=12.4)

27.1 (σ=1.1) 27.5 (σ=1.7)

Something relevant to be considered at this point is the fact that there is almost no difference between the thermal environments (0.4 °C on average higher in environments that are not facing the gardens), indicating little interference from gardens in relation to the air temperature of indoor environments nearby them. The relative humidity was presented as 10.3% higher in environments facing the gardens, thus verifying the potential of green areas in the air humidification, which is caused by the plants evapotranspiration. As concerns wind speed, due to the fact that environments have to be with closed doors, because of the risk of contamination, there was almost low wind speed, except for places where there was a fan. The average speed measured was 0.02 m s-1 for both groups. Although the windows that were facing the gardens, behind closed doors there was no

cross-ventilation, which makes the air exchanges with the outside slower. As all the rooms are set on a comfortable situation according to the Brazilian Federation of Hospitals, which determines temperature by 24 °C, there was also a disagreement about the Norm 17 of the Labor Ministry, with air temperatures around 4 °C above the established threshold level and relative humidity higher. The low air speed according to this standard. 3.2. Predicted and real thermal sensation The PMV index concentrates on +1 (Slightly warm) for both groups of employees interviewed (Figure 3), indicating a general thermal discomfort in the workplace environments. Based on ISO 7730 (1995), the PPD for a population where 13% of people are under condition of thermal neutrality, indicates 55% of people dissatisfied. Comparison of PPD between the two groups showed no significant differences between them. Contrary to the expectations, the PMV showed a situation of better thermal comfort in environments that do not have direct contact with the gardens. As the humidity was elevated during the monitoring period, the discomfort of the environment facing the gardens was referred to. Facing higher temperatures and low air speed, the discomfort rises up with increasing relative humidity, since the latent heat loss by sweating becomes smaller. The actual thermal sensation (ASV), obtained through questionnaires, concentrates on +0 (Neutral) for both groups of staff surveyed (Figure 5), with 45% of the vote. The overall percentage of people with mild heat down to 35%, which means 37% less than the PMV (Figure 4). The percentage of neutral answers is 5% higher for the group of interviewees whose work environments are (open) facing to the gardens, in relation to the other group. However, through the distribution of votes it has not been possible to identify any trends in thermal sensation which can be attributed to the existence of the gardens. Despite the thermal sensation which tends to be hot, 63% of the interviewees have answered feeling thermally comfortable, regardless of no visual contact with the gardens. The comparison between the real (ASV) and predicted (PMV) thermal sensation (Figure 6) leads us to consider the visible difference between these indexes, indicating subjectivity in the perception of comfort and adaptability to human microclimates. As the PMV indicates 13% neutral, 45% of the population has related to be in this thermal situation, 61% were comfortable, even feeling mild heat or heat, indicating that the thermal satisfaction differs from the thermal sensation.

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90%

76% 69% 72%

Percent of Votes

80% 70% 60% 50% 40% 30% 20% 10%

16% 7%

13%

13%

17% 15% 0% 1%

0% 0 Neutral

1%

+ 2 Warm + 3 Hot +1 Slightly warm

Predicted Mean Vote (PMV) Without green areas view With green areas view Total Figure 4: Predicted Mean Votes in hospital environments.

Percent of Votes

60% 48%

50%

43%

40%

45% 40%

20%

0%

24%

25%

30%

10%

35%

15%

18%

1% 3% 2%

+ 2 Warm -1 Slightly 0 Neutral +1 cool Slightly warm Actual Sensation Vote (ASV) Without green areas view With green areas view Total

Figure 5: Actual sensation votes in hospital environments survey results.

80%

72%

Percent of Votes

70% 60% 50%

45%

40%

35%

30% 20% 10% 0%

13% 2%

18% 15% 1% 0%

+ 2 + 3 Hot 0 +1 -1 Slightly Neutral Slightly Warm warm cool PMV ASV Figure 6: Comparison of predicted mean votes (PMV) and actual sensation votes (ASV) results.

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Apart from and at the same time, regarding the individual factors that interfere in the PMV, it can be observed that thermal resistance of clothes had little contribution to the heat discomfort. The clothes were generally light, with average thermal resistance of 0.56 clo. But, the metabolic rate indicates some implications in thermal comfort. The staff performed light activities, an average of 1.9 met. So, it has been noticed that the staff group which performs more physical effort, like the cleaning area workers or laundry and maintenance workers (3 Met), are the ones who were feeling the heat more intensively (PMV +2).

4. CONCLUSION All the green areas and gardens of Hospital Santa Casa de Valinhos have been improved recently with the implementation of new species of plants. Despite the improved appearance of the landscape, the trees have not yet gained significant size and height to modify the internal microclimate of the hospital environments which have their openings spaces overlooking these green areas. What should be emphasized at this point is the fact that while comparing the microclimate environments with and without openings to the gardens; it was observed that the relative humidity was the climatic variable that best expresses the influence of vegetation on microclimate, becoming 10.3% higher in environments facing the green areas. Air temperature has shown no significant differences, being around 27 ºC. Wind speed was low, near zero, in all environments, except in those with mechanical ventilation. As the hot, humid and poorly ventilated microclimate caused discomfort in hospital environments, although large windows were overlooking the gardens, there is a need to keep the bedroom doors closed, because of the risk of contamination. Consequently, there is no cross ventilation, which would be interesting so as to increase the air speed and improve comfort conditions in this hospital. There is no statistically significant difference in the thermal comfort conditions of the hospital staff that either have or not visual contact with the green areas. The PMV indicates that 72% of the interviewees suffer from mild discomfort for heat, and only 13% were neutral. The PPD indicates about 55% were “dissatisfied”. About the stated votes of comfort obtained from the questionnaires, they have shown a significant increase in the “comfortable” population, which is of 45%. The thermal satisfaction was reported by 61% of the staff indicating the subjectivity of human perception and also the thermal adaptation. To sum up, the results have indicated that the hospital gardens influence the microclimate of indoor environments. However, in hot climates, high humidity air can make the conditions worse for the thermal comfort of the users, in conditions where air speed is calm. A final consideration should be to improve the thermal comfort level, and hereby it is suggested the

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

implementation of opposing openings for a better ventilation performance as well as adequate standards of hygiene related to health care settings, to increase the speed of winds. In relation to the gardens, it´s suggested the growing of some varied range of tree species, spaced with tops higher than the height of the windows, because the “foliage” can reduce wind speed.

5.

ACKNOWLEDGEMENTS

Authors would like to thank to CAPES for the financial support and Santa Casa Hospital employees who have cooperated with this project.

6. REFERENCES [1] WHITEHOUSE,S;VARNI,J.W.,SEID,M.,COOPE R-MARCUS C., ENSBERG, M.J., JACOBS,J.R., MEHLENBECK, R.S. (2001) Evaluating a children's hospital garden environment: Utilization and consumer satisfaction. Journal of Environmental Psychology: v.21, p.301-314. [2] KAPLAN. R. (2001) The Nature View from Home: Psychological Benefits. Environmental Behaviour: available at http://www.sagepublications.com, p.507-541. [3] KAPLAN. R.; KAPLAN (1993). S. The role of the nature in the context of the workplace. Landscape and Urban Planning: v.26, p.193201. [4] ULRICH,R.S.View through a window may influence recovery from surgery. Science, v.224, p.420-421, 1984 www.sciencemag.org (access in march, 2007) [5] ULRICH, R.S. Effects of Interior design on Wellness: Theory and Recent Scientific Research. Journal of Health Care Interior Design, majorhospitalfoundation.org, 1991 (access in june, 2010). http://www.majorhospitalfoundation.org/pdfs/Effe cts%20of%20Interior%20Design%20on%20Well ness.pdf. [6] ULRICH, R.S. Health Benefits of Gardens in Hospitals. Paper for conference, Plants for People, International Exhibition Floriade, 2002, 10p. [7] MARCUS C.C.; BARNES, M. Gardens in Healthcare Facilities: uses, therapeutic benefits and design recomendations. Martinez,CA: The Center for Health Design, 1999, 624p. [8] ZEISEL, J. (2007) Healing gardens for people living with Alzheimer’s, in: THOMPSON,C.W.; TRAVLOU,P. ed. OPEN SPACE-People Space. NY: Taylor and Francis, 2007 , p. 137-150. [9] TAYLOR, A., KUO, F., SULLIVAN, W.C., Coping with ADD, the Surprising Connection to Green Play Settings, Environment and Behavior , v. 33, nº 1, 2001, p.54-77. [10] FJELD,T. The Effect of Plants and Artificial DayLight on the Well-Being and Health of Office Workers, School Children and Health Care Personnel, Seminar report: Reducing health complains at work Plants for people, Int. Hort. Exhib.Floriade, 2002, 10p. [11] GRAHN. P.; STIGSDOTTER, U.A. Landscape planning and stress. Urban forestry & Urban greening, v. 2, n.01, 2003, p. 01-18. [12] HANSMANN. R.; HUG. S. M.; SEELAND. K. Restoration and stress relief through physical activities in forest and parks. Urban Forestry & Urban Grenning, v. 6, n. 4, 2007, p.213-225. [13] HARTIG, T.; KORPELA,K; EVANS & GÄRLING, A Measure of Restorative Quality in Environments, Scandinavian Housing & Planning Research, 1997, v. 14 p.175-194.

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[14] HARTIG, T., Three steps to understanding restorative environments as health resources, in: THOMPSON,C.W.; TRAVLOU,P. ed. OPEN SPACE- People Space.NY: Taylor and Francis, 2007 , p. 163-179. [15] SPIRN,A.W. O Jardim de Granito: a natureza no desenho da cidade. São Paulo: Edusp, p.25-52, 1995, 360p. [16] NIKOLOPULOU, M.; LYKOUDIS, S. Thermal comfort in Outdoor Spaces: Analysis across different European countries. Building and Environment, v. 41, 2006. [17] FONTES, M.S.G.C.; ALJAWABRA, F.; NIKOLOPOULOU, M. Open Urban Spaces Quality: a Study in a Historical Square in BathUK. In 25 th Conference on passive and Low Energy architecture - PLEA, Dublin 2008, Proceedings… CD-ROM, 7p. [18] DACANAL, C. Conforto térmico em Espaços Livres Públicos: Estudo de Caso em Campinas, SP. In: ENCONTRO NACIONAL, 10., ; ENCONTRO LATINO AMERICANO DE CONFORTO NO AMBIENTE CONSTRUÍDO,6., 2009. Natal. Anais... ENCAC, 2009,10p. [19] OLIVEIRA, L. A.; MASCARÓ, J. J. Análise da qualidade de vida urbana sob a ótica dos espaços públicos de lazer. Ambiente construído, v. 7, n. 2, 2007, p. 59 – 69. [20] PIVETTA, K. F. L.; SILVA FILHO, D.F. Arborização urbana (Boletim Acadêmico), Ed. Unesp/ FCAV/ FUNEP, 2002, 74p. [21] VASCONCELOS, R.T.B. Humanização de Ambientes Hospitalares: Características Arquitetônicas Responsáveis pela Integração Interior / Exterior. Dissertação de mestrado apresentada ao programa de Pós-graduação em Arquitetura e Urbanismo da Universidade Federal de Santa Catarina, Florianópolis, 2004, 177p. [22] TALAIA, M. A. R. O Conforto Humano e as Alterações Ambientais. Proceedings of the XXVIII Jornadas Científicas, La Meteorologia y El Clima Atlânticos, 5º Encuentro Hispano-Luso de Meteorología: La Meteorología y Climatología en los Sectores Público y Privado, CDROM, ISBN: 84-8320-261-1, Badajoz, Espanha, p.474-483, 2004. [23] MANUAIS de Legislação Atlas. Segurança e medicina do trabalho. São Paulo, Atlas. 46, ed.2001. [24] INTERNATIONAL ORGANISATION FOR STANDARDIZATION, ISO 7730; Moderate thermal environments - determination of the PMV and PPD indices and specifications of the conditions for thermal comfort, Geneva, 1994. [25] FANGER, P.O. Thermal comfort – Analysis and applications in environmental Copenhagen: Engineering, 1970. 244p.

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[26] RUAS, A. C.; Sistematização da avaliação do conforto térmico em ambientes edificados e sua aplicação num software. Campinas: Tese (Doutorado em Engenharia Civil) – Universidade Estadual de Campinas, 182p. 2002.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Performance of Outdoor Thermal Comfort and Indoor Heat Flux of Rooftop Lawn Greening in the Subtropical Climate Kuo-Tsang HUANG 1, Chuang-Hung LIN2, Han-Hsi LIANG2 1

Department of Landscape Architecture, National Chiayi University, Chiayi City, Taiwan 2 Department of Architecture, National United University, Miaoli County, Taiwan

ABSTRACT: The benefits of rooftop greening are ascertained in thermal perspective. It effectively reduces the near surface ambient temperature and the reflected irradiation from the rooftop slab, thus increases the thermal comfort environment above the lawn and reduces the heat transferred through the rooftop slab. The former effect enables the potential usage of the rooftop spaces for human activity and helps to alleviate the urban heat island effect while the latter is able to reduce the interior space cooling load especially in subtropical climate. A field experiment was carried out in the subtropical central Taiwan to quantify these two performances. Indices of mean radiant temperature (MRT), wet bulb globe temperature (WBGT), and heat flux rate were used to explain and discuss the performance of thermal comfort and heat flux of the rooftop lawn. The results confirmed that rooftop lawn contributes benefits both on its outdoor surrounding environment and the indoor energy beneath. Keywords: green roof, mean radiant temperature index, wet bulb globe temperature index, heat transfer

1. INTRODUCTION Taiwan where its central is located right on the Tropic of Cancer is a fast developed and over populated island. The climate here is of subtropical climate characteristic. High concentration of buildings is very common seen in many urban districts result in varies urban environmental issues, such as lacking enough recreation areas, low urban greenery cover ratios, and moreover the urban heat island effect (UHI). Green roofs (or planted roofs) as an extension of urban green areas and recreational open spaces not only provides visual enhancement, it also contributes to the thermal benefits in buildings and their surrounding environments. There are direct and indirect effects of green roof from thermal perspective. The direct effects of green roof are their thermal benefits in reducing surface temperatures of roofs and heat transfer into the rooms underneath. It will directly contribute to improving the indoor thermal environment and thermal performance of buildings. Indirect effects of green roofs refer to its potential thermal impacts on surrounding environment. It will contribute to creating better outdoor thermal environment and mitigating the UHI effect [1]. Besides, because most the rooftop zones are of private estate, low maintenance is usually required to sustain a rooftop garden. Extensive roof greening style such as lawn or turf greening is much favourable and feasible solution due to its lower maintenance and lower initial cost benefits. Incentives from the government were also been proposed to encourage rooftop greening in Taiwan recently. This is why the lawn planted rooftop is therefore chosen for studying in this research. Although several studies on green roofs have been carried out worldwide, they are limited to certain

locations, climate and planting types. These data are not directly applicable to the subtropical environment. The objectives of the research are as follows:  To investigate the environment thermal comfort enhancement over the rooftop lawn greening.  To understand thermal insulation performance of the lawn greening which contributes to the reduction of interior heat gain. The first subject intend to quantified the reduction of ambient temperature and the surrounding longwave radiation due to the rooftop lawn, which is essentially the two key factors that affect the people’s willing of using rooftop as an recreation purpose. The second subject attempts to quantify the interior cooling load reduction amount from the lawn layer insulation perspective.

2. METHODOLOGY An experiment field of lawn greening were established on top of a four-storey student centre building located in National Chiayi University at Chiayi City, Central Taiwan, where its latitude is of 23.6 degree north. Five meter square lawn planted area with 10 cm growing medium was created at the centre of the rooftop to avoid any rooftop object shading overlay (Fig.1). The surface material of the rooftop exposed slab is grey concrete tile which is very common material used for flat roofs in Taiwan. Space underneath the rooftop experiment field is public corridor. Cynodon dactylon was chosen as the rooftop lawn to plant over the 10 cm-thick Finland KEKKILÄ peat moss studied herein, because of its drought and hot enduring as well as fast growing features. Furthermore, an additional 3 cm perlite layer for drainage was placed below the growing medium separated by a thin nonwoven layer. Therefor a minimum of 13 cm thick lawn grass layer paved over the original concrete rooftop was formed. Manual

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irrigation was performed when there was no natural precipitation during a consecutive period of one week to wet the grass. The experiment last for over a year and was carried out from 8th September 2008 to 9th October 2009. The comparative set (i.e. control set) of the experiment without rooftop greening where neighboured to the lawn planted field about five meters away was also carried out simultaneously (Fig.2). 

Figure 1: A five meter square lawn planted area with 10 cm substrates were created at the centre of the rooftop

For measurements of outdoor thermal comfort, two sets of instruments were placed above the lawn and the exposed slab respectively. Each set includes sensors for measuring globe temperature (Tg), drybulb temperature (i.e. ambient temperature), relative humidity, wind velocity and naturally ventilated wetbulb temperature. All the sensors were horizontally aligned at the height of one meter above the ground surface. Instruments used herein includes calibrated T-type thermocouples placed in the white louver shelters for measuring ambient temperature, black globe thermometers were used to measure Tg, omnidirectional hotwire air speed transmitters for measuring wind velocity. Naturally ventilated wet bulb temperature could be obtained via placing cotton-wrapped Pt100 sensor within 2/3 water filled vacuum stainless bottles. Moreover, pyranometer was installed to record the incident total horizontal solar radiation that reaches to the surface. All the values were simultaneously recorded by a Delta GL800 data recorder at an interval of 10 seconds (arranged as in Fig.3). For measurements of indoor heat flux, another two sets of instruments were deployed above and under the floor slab with and without lawn conditions. Thin heat flux sensors were seamlessly attached beneath the floor slab with aluminium foil cover over it to prevent heat intervention from the corridor making sure the measured values only accounts for heats that transferred through the floor slab. Moreover, to further understand the fluctuations of the surface temperature of the slab due to lawn greening, several T-type thermocouple wires were placed above and beneath the floor to fetch values of surface temperature, as shown in Fig. 4. The indoor ambient temperatures were also taken measured by placing thermocouples five centimetres under the floor slab ceiling. SR A

B

C

D

A

B

C

D

Figure 2: The comparative set of the experiment S S S T

S Q

S

Q

T

Figure 4: Sensors deployment in the field (A: globe temperature, B: ambient temperature & relative humidity, C: wind velocity, D: naturally ventilated wet bulb temperature, S: surface temperature, Q: heat flux, SR: solar radiation)

Figure 3: Values of varies parameters were constantly recorded in the data logger every 10 seconds

2.1. Deployment of the measurements The experiment in the research comprises two sections, one is for studying outdoor thermal comfort and another is for understanding the effect of indoor heat flux reduction.

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Figure5: Indoor heat flux, surface temperature and indoor ambient temperature measurement

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

2.2. Indices for describing thermal comfort There were two indices used to describe thermal environment. The mean radiant temperature (MRT) is a key variable in thermal calculations for the human body. It is the uniform temperature of an imaginary enclosure in which radiant heat transfer from the human body equals the radiant heat transfer in the actual non-uniform enclosure [2]. The simplified calculation method of MRT can be easily obtainable using the physical measured parameters as described in Eq. 1. The MRT index is closely related to parameters including globe temperature (Tg), ambient temperature (Ta) and wind velocity (Wv). It can efficiently responses the long-wave radiation from surrounding environment enclosure which is considered the most influential factor to the comfort sensation. Furthermore, the energy balance of one's body is highly responsive to changes in MRT and is more suitable and direct for describing human's thermal sensation. 0.5 MRT=Tg+0.237×(Wv) ×(Tg-Ta)

(Eq.1)

The wet bulb globe temperature (WBGT) index is widely used for estimating the heat stress potential of industrial environments concerning activity status. It is a composite temperature used to estimate the overall effect of temperature, humidity, and solar radiation on humans. Ambient temperature (Ta), naturally ventilated wet bulb temperature (Tnwb), and globe temperature (Tg) each multiplied by a corresponding weighted values to calculate WBGT index as in Eq. 2 [3]. WBGT=0.7×Tnwb+0.2×Tg+0.1×Ta

Figure 6 reveals that when without lawn greening, the maximum temperature of the exposed slab surface could reach 61.3℃ seven minute later when solar radiation was at its daily high of 1015 W/m² at 12:52. The maximum daily variation of surface temperature was 35.4℃. For lawn planted area, the surface temperature measured during daytime was not as high as that of the exposed slab surface. The maximum surface temperature of lawn field was around 32.4℃ and the maximum daily variation of surface temperature was only 3.5℃ which is much lower than those measured on the exposed slab surface. The reason could be due to the combination effect from the grass leaf shading and the evaporation of moisture in the soil. As for the surface temperature beneath the floor slab, maximum surface temperature of 41.1℃ was occur at 17:06, at which time was around four hours delay when its top surface temperature reaches its high. For lawn planted area, maximum surface temperature of 32.3℃ was occur at 23:04, at which time was around 10 hours delay comparison to the exposed slab. It indicates that with a 13cm substrate layered lawn greening on top of the roof could extend the time lag of sub-surface temperature to around six hours. With this effect it could also alleviate the daytime indoor cooling load by delaying heat transfer into space.

(Eq.2)

3. RESULTS AND DISCCUSION Although the experiment lasts for one year, it is rather difficult to process such a huge amount data, therefore, typical day was selected for analysis. The day that ten days before it is without precipitation or cold draft or other exceptional weather conditions is considered a typical day to rule out unusual weather influences. Moreover, the daily averaged differences of dry-bulb temperature, wind velocity and total horizontal solar radiation of the typical day should all fall between 1% margin compare to long-term recorded seasonal data. According to the above criteria, 10th December 2008 and 10th June 2009 were selected as typical days for further analysis each representing winter and summer respectively.

Figure 5: Surface temperature variation above slab in different seasons

3.1. Surface temperature variation The top surface temperature diurnal variation of the typical days selected for winter and summer are plotted as in Fig. 5. It shows that the variation patterns from the two seasons, either with or without lawn, are of similar shape. The major difference is its absolute values. By comparing the surface temperature drop in winter, temperature decreases more on the exposed slab surface than on the lawn soil surface. With the similar variation pattern observed from Fig.5, therefore, for the following discussion, only the selected typical day of summer is discussed afterward.

Figure 6: Diurnal surface temperature variation in summer

3.2. Outdoor thermal comfort performance On discussing outdoor thermal comfort of spaces between above lawn and above exposed concrete

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slab, Tg, MRT index, WBGT index, ambient temperature and relative humidity measured at a height of one meters from above both conditions were compared. The daily averaged ambient temperature above the lawn was 0.24℃ lower than the exposed slab. After sunset there was significant reduction of ambient temperature above the lawn planted area and lasted until the next day sunrise. It indicates that the lawn constantly lowering the ambient temperature during non-solar-radiation period. Maximum difference of 2℃ was observed at around 7:00. The comparison of relative humidity measured at one meter heights above exposed slab surface and lawn planted area is shown in Fig.7. When in night time, lower relative humidity was observed above the lawn planted area with a maximum difference value of 10.48%. But when in daytime it was a bit higher by around 5%, it could be due to the grass transpiration in daytime that slightly moisturize the surrounding air. Based on the ambient air temperatures, global temperatures (Tg), and wind velocity measured at one meter heights, the MRT above the exposed slab surface and lawn area were calculated. The Tg represents the integrated effects of radiation and wind. The measured Tg and calculated MRT were plotted in Fig.7 and Fig. 8 respectively. There were obvious differences in Tg and MRT on above lawn or exposed slab surface. Maximum differences of Tg and MRT were 2.6℃ and 3.19℃ was occurred at 13:18 when the solar radiation was strongest. It was due to the surface temperature on the exposed slab was relatively higher than that of the lawn planted surface, thus caused long-wave radiation emitted a lot more from the exposed slab surface resulting in higher Tg and MRT occurred. This indicates that lawn planted field will provide more comfortable environment for outdoor activities than with exposed slab conditions during daytime. On the other side, when during night time, heat dissipation was more quickly on the exposed slab surface than on the lawn planted area which leads to drastic surface temperature drop on the exposed slab surface. Without solar radiation, the radiation part of Tg and MRT mainly depends on the amount of long-wave radiation emitted from surrounding surfaces. When in early morning, around 6:00, surface temperature on the exposed slab surface reached to a maximum difference of 3℃ lower than the lawn planted area, resulting in 0.7℃ and 0.87℃ lower the Tg and MRT encounters on the exposed slab surface conditions respectively. Wet bulb globe temperature (WBGT) was also studied in this research, providing more overall view on the heat stress issue that relates to thermal comfort. The calculated WBGT was drawn in Fig.7 together with MRT over layered. According to regulations from Taiwan Council of Labour Affairs, maximum WBGT of 30.6 ℃ for continuously light work load activity is recommended. With the above criteria, from sieving the calculated WBGT during working hours (i.e. from 8:00 to 18:00), there was 52.3% and 63.5% for with and without lawn conditions respectively that would fall out of the

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criteria. There was 11.2% higher probability unable to meet the criteria on above exposed slab surface than on above lawn planted area. Furthermore, according to Hwang & Lin [4], a research of defining semi-outdoor thermal environment comfort zone for Taiwan, the result reveals that while MRT is between 21 to 47℃ it is considered comfortable. From this point of view, there is a probability of 24.79% the MRT above the lawn will fall out the comfort zone. Compares to the MRT above the exposed slab, there is 31.74% probable of falling out the comfort zone, which is 6.95% higher. All the fell-out period is between 8:00 to 16:00 in summer. 3.1. Indoor heat flux fluctuation On indoor heat flux, a considerable rate of heat flux was observed under the floor slab with exposed slab on top. The maximum heat flux, 48.5 W/m², occurred at 17:07, which was five hours later than daily maximum total horizontal solar radiation occurred. Heat gain was observed nearly all day long, except around five minute period at 8:50 heat loss was encountered. Diurnal heat flux variation could reach 50.7 W/m², as indicated in Fig. 9.

Figure 7: Diurnal relative humidity and globe temperature variation in summer

Figure 8: Calculated MRT & WBGT variation on a summer day at the height of 1m

For the area with lawn planted condition, most heat flux observed underneath the floor slab during daytime was of negative values, i.e. the space was encountering heat loss. The heat loss began at approximate 10:00 and continued till around 21:00 at night, which had positive influence on reducing

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

indoor cooling loads during work hours in daytime. Consecutive indoor heat gain began during the time period other than heat lost period, which was mainly at night. There was apparent time lags regarding heat gains under lawn planted area, as indicated in Fig.9, solar heat gain during the daytime was lagged for nearly 14 hours. Comparison with the exposed slab condition, there was only approximate four hour’s lags. Which indicates that with lawn planted above the rooftop, interior space underneath would not instantly response to the solar radiation that gain from top of roof during daytime thus results in less responsive to outdoor climate. The diurnal variation range of heat flux under lawn condition was 11.4 W/m², which is only around one fifth amount comparing to the exposed slab condition, the peak heat flux wasn’t apparent. The total heat gain of a day was -0.25 Wh/m² with lawn planted condition and was 19.21 Wh/m² without lawn planted. The lawn had a significant influence on the amount of heat flux transferred possibly due to its leaf’s sun blocking effect and the heat dissipation in substrate layer by both heat absorption and evaporation effect. Figure 10 shows the differences of transferred heat flux and indoor room temperature between with and without lawn conditions. Maximum indoor temperature difference, 3.1 ℃ , was detected at around 16:00 which corresponded to the maximum heat flux difference, which is around 50 W/m², occurring time. Comparing to Fig.9 and 10, it shows that the lawn planted layer provides a good heat storage as well as heat dissipating means, reducing the fluctuation range of indoor temperature and transferred heat flux. The interior space underneath the lawn planted roof will has more stable indoor climate which is significantly contributes to improve thermal comfort and reduce energy consumption.

parameters’ reduction effect. Conclusions drawn from this research are as follows: 1) There was reduction up to 9.12℃ on average for top surface temperature, while there was averaged 4.24℃ reduction of surface temperature beneath the slab. 2) Cooling effect from the lawn was confirmed by comparing the ambient temperature, an average reduction of 0.24 ℃ was detected above the outdoor lawn planted area, while there was averaged 1.22℃ reduction for indoor temperature. 3) Time lag effect of lawn planted area was confirmed by investigating the diurnal heat flux variations. There was 19.49 W/m² on average reduction for heat flux and cause extra 10 hours’ time lags with lawn planted above the rooftop. 4) Less long-wave radiation emitted from the lawn planted roof was confirmed through comparisons of Tg and MRTs measured on site. Diurnal averaged 0.99℃ and 1.16℃ reduction for Tg and MRT were found in the study respectively.

Figure10: Diurnal heat flux & indoor temperature difference

5. ACKNOWLEDGEMENTS The authors would like to express their greatest appreciation to Taiwan National Science Council for financial support to the research.

6. REFERENCES

Figure 9: Diurnal heat flux variation comparison

4. CONCLUSION In this research, comparisons of outdoor thermal comfort performance and indoor heat flux between lawn planted area and exposed slab area were made through investigating onsite field experiments in subtropical central Taiwan. Both with lawn and without lawn planted conditions on top of roof were established and were taken measurements simultaneously yearlong for studying varies

[1] Wong, N.H., et al., Investigation of thermal benefits of rooftop garden in the tropical environment. Building and Environment, (2003), V.38 (2): p. 261-270. [2] ASHRAE, ASHRAE Handbook – Fundamentals Chapter 8. (2005), Atlanta, USA: American Soceity of Heating, Refrigerating and AirConditioning Engineers, Inc. [3] Dukes-Dobos, F. and A. Henschel, Development of permissible heat exposure limits for occupational work. ASHRAE Journal, (1973), V.9: p. 57. [4] Hwang, R.-L. and T.-P. Lin, Thermal comfort requirements for occupants of semi-outdoor and outdoor environments in hot-humid regions. Architectural Science Review, (2007), V.50 (4): p. 60-67.

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Redefining Pavilions: Improving Upon Outdoor Comfort Conditions A performance study of London pavilions Ellen CAMERON, Milena STOJKOVIC, Konstantina SARANTI and Olga CONTO Sustainable Environmental Design Programme, Architectural Association School of Architecture, London, UK ABSTRACT: Pavilions have become a forum for explorative ideas and design due to their innate connectivity to the environment and lack of specific performance standards. This study seeks to redefine pavilions according to their ability to improve upon outdoor conditions. Based on fieldwork and simulations, the inputs of sun and wind, were assessed to find what made an effective difference in pavilion occupancy patterns. It was found that an environmental performing pavilion must have access to the limiting factor of comfort as defined by its location and climate specific criteria in order to maximize occupancy and time spent. Keywords: outdoor comfort, pavilion structures, sun, and wind.

1. INTRODUCTION A pavilion can be narrowly defined as an outdoor shelter whose function is to protect from extreme environmental conditions of rain, sun, and wind. It exists in a specific place and time and is perhaps the most locally microclimatic specific building type due to its coupling with the environment. This has made the subject of pavilions difficult to standardize. CIBSE Guide A Environmental Design states that “the standard does not cover hot or cold stress in thermally extreme environments, or comfort in outdoor spaces” [1].

1.2. Case Studies After reviewing built form and occupant use in pavilions throughout London, the pavilion typology became defined by two key variables: programmatic requirements and relative coupling to the environment (Fig. 1). Spot measurements of wind speed, lux levels, and temperature were correlated to occupant observations and interviews to understand how occupancy and activity over time and space were affected by environmental conditions. Two pavilions were analysed in detail: Frank Gehry’s 2008 Serpentine Pavilion (Fig. 2) and Hay’s Galleria (Fig. 3).

 

  Figure 1: Pavilion typology: Coupling to the environment is determined by the percentage opening to the exterior.

1.1. Key Research Questions To address the lack of performance standards, the goals of this study are to: (1) establish which environmental factors have most influence on the conditions in a pavilion; (2) establish if there is a general application of these determinate factors dependent on climate, surrounding environment and pavilion type; (3) define environmental performance criteria for pavilions based the role of the occupant in terms of program, expectations, perceived control, physical and psychological adaptation. By combining these elements, this study then outlines what can be expected of pavilions as a microclimate modifier and programmatic device.

  Figure 2: Serpentine Gallery Pavilion 2008, as example of a pavilion with an open programme in an open space.

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modulating solar exposure, on-site observations and spot measurements were used to calibrate models to calculate the amount of solar radiation available 2 (W/m ) on different times of day and year in case study locations. Analysis programs were then used to simulate different situations and to test potential control or manipulation of available solar radiation Shadows are simulated by Ecotect [5], Illuminance is mapped and measured with Radiance [6] under conditions of spot measurements with sunny sky. Satel-Light [4] data for London is used for percentage frequency of sky types. Direct and diffuse radiation values are calculated based on Meteonorm v6 data from case studies respective weather stations [3]. 2.2 Wind Analysis  

 

 

Figure 3: Hay’s Galleria is an urban pavilion, which is occupied year round with open and strict programme activities.

1.3. London Climate The London climate can be generally characterized as the absence of non-extreme conditions throughout the year but with minute-by-minute changes on a daily basis. In the “…UK weather can give considerable variations of outdoor temperature at much shorter than monthly intervals” [2]. In London, the mean monthly temperature ranges from 3.4°C in February, the coldest month of the year, to 19.7°C in July, the warmest month of the year [3]. Frequency of sky types had a similar distribution throughout each month and yearly averages of 30% sunny, 42% intermediate, and 27% cloudy skies [4].

2. ANALYTIC WORK Due to their coupling to the environment, pavilions are not mechanically cooled, heated or ventilated. As an outdoor structure for pavilions Tinterior = Texterior, therefore the tools of pavilions to modulate the environment are mean radiant temperature and wind. The effects of wind can be varied through its controlled presence or absence. Mean radiant temperature is affected by the protection or enhancement of solar gains and material characteristics.

 

2.1. Solar Analysis In London’s climate with a yearly average temperature of 10.7°C, solar heat gains generally are needed for increased occupant comfort. In this study, the amount of solar radiation available (W/m2) on different times of day and year is calculated in each case study location. To determine the key factors in

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Wind velocity has the ability to lower temperatures in summer and winter. It was observed that spaces with long-term employees were more enclosed but had increased complaints due to cold and wind. The analysis sought to understand how the perception of wind velocity changes depending on occupant activity and to determine which velocities of wind are entering the pavilion and how they may differ from exterior conditions based on comparison of interior and exterior spot measurements and Meteonorm 6 data [3]. Equations were then used to estimate the effect on occupant comfort in terms of the dT the wind could have on an occupant in summer and winter conditions. This data was then correlated to occupant responses in the pavilions. Applied equations are from PLEA Note 3 Thermal Comfort [7] and Arens [8] Equation for Summer Cooling [7]: dT = 6¥ (v-0.2) – 1.6¥ (v-0.2)2. Wind Chill Temperature [8]: WCI = (12.15 + 11.6 (√v) − v) ¥(33 − DBT) WCT = 33 − 0.03738 ¥ WCI Each equation had limitations for use due to assumptions made regarding internal/external situations, clo, and outside temperature. It is noted that there may be an innate assumption in comparing the two equations that indoor situations are a longterm occupancy while outdoor situations are short term.

3. OPEN PROGRAM, OPEN SPACE Open space pavilions have a greater ability to modulate their environmental characteristics due to the lack of external structures and buildings affecting the microclimate conditions. The Serpentine Pavilion is only occupied in the summer months with mainly an open program (Fig. 4).

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

In order for this environmental effect to work the sky type must be sunny or intermediate skies as there is no shade when the sky is overcast. The second factor of materiality deals with the opacity of the fritting and the transmittance of the clear glass in relation to the amount of solar radiation allowed into the space and onto occupants and surface materials. The orientation affects where the shadow will fall inside of the pavilion and depends on the time of year and day. Sunny skies are needed for the chaotic sunshade effect. The pavilion was open in London from July 19th to October 20th. According to Satel-Light data, sunny skies would only occur 34.25% of the time the pavilion was open to the public [4]. This compares with 81.25% of the time if the pavilion were located in a climate like Athens, Greece. Calculations for 12:00 noon on the opening date, the 20th of July, show the solar radiation levels at the Serpentine pavilion (Fig. 5). At their highest level, a potential increase of 8-10 K in the operative temperature for occupants in non-shaded positions and dependent on clothing absorption levels (Table 1). This is a very large and substantial increase in operative temperature for the occupant that could potentially lead to uncomfortable conditions and leaving or moving to a shaded position within the pavilion.

 

Figure 5: Solar Radiation in Serpentine Gallery Pavilion 2008 after Meteonorm v6 2008 [3] Figure 4: Frequency of events in the Serpentine Gallery th th Pavilion from July 20 to October 19 . Rain days from Met Office [9]

3.1. Serpentine Solar Analysis There are three determinate factors for solar radiation availability and control in Gehry’s Serpentine Pavilion. In order of importance, the first is the sky type, followed by materiality and orientation. Gehry attempts to create a chaotic environment within pavilion by using the fritting on the glass canopies as a tool to create a varied condition of sun and shade throughout the pavilion.

 

Smaller increases in operative temperature occur when an occupant is sitting in a position in full shade within the pavilion; however, when there are high levels of diffuse radiation there can still be up to a 5 K increase, which could make people uncomfortable. On the other hand in London, where sunny skies are present only 30.25 % of the time of the year, it has been observed that most people enjoy the sun undeterred by potentially uncomfortable hot or cold temperatures.

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4. STRICT PROGRAM, URBAN SETTING

Table 1: Solar radiation availability and operative temperature at noon after Humphreys 2006 [1] Date 20 Jun 20 – Jun 19 – Oct 19 – Oct

% Shade

Max Incident (W/m2)

Incident Radiation (W/m2)

5.88

36.88

57.24

Outdoor Temp (ûC)

Aprox Operative Temp. Increase (K)

20.4

8-10

Environmental performance of ground level pavilions within the urban setting is highly dependent on the surrounding structures and components of the urban environment. Hay’s Galleria is occupied year round with open and strict program activities.  

6.79

45.65

47.57

21

3-5

4.1. Hay’s Galleria Solar Analysis

5.48

40.40

54.12

14.8

5-9

16.39

51.58

32.03

14.8

1-2

Solar access for Hay’s Galleria is determined by its height-width ratio and orientation. Height-Width ratio is primary regardless of orientation because in the upper latitudes where London is located, a ratio of 1.2:1 will result in self-shading for a portion of each day during the year. The North-South orientation of Hays Galleria is the next key factor, as it will determine the portion of each day during the year when the structure will self-shade. The surroundings are not an environmental factor affecting the solar access, as Hay’s is the tallest of nearby structures. The surroundings are an architectural and psychological factor as the open face of Hays Galleria is oriented towards the Thames River. As a result of its height-width ratio and enclosed south oriented facade, the Galleria is in 100% shade for 95% of the year (Fig. 6). Direct sunlight only enters when the solar altitude is greater than 35° and the solar azimuth is between 195° and 225°. This occurs only occurs during the tourist filled summer months between the lunch hours from 12:00-15:00. Consequences of the almost constant overshadowing are daytime use of internal lighting, complaints of cold despite high clo values and shorter winter vendor hours. Due to the condition of total shade in the winter there is only a 0-1 K elevation in operational temperature in winter; this is a minute temperature gain, which will likely not be an effective difference for an occupant’s comfort. On the 21st day of June at 13:00, the peak time for solar radiation, there is a potential for a 3-5 K increase, which could lead to potential thermal discomfort in some locations of the galleria.

The Serpentine Pavilion’s open space location with minimal overshadowing by adjacent trees allows for shading devices to be used for solar control, in Gehry’s case: fritting, to create a variation of concurrent conditions and therefore a choice to sit in sun or shade. 3.2. Serpentine Wind Analysis In the summer London has a prevailing southwesterly wind, and in the Serpentine, as a freestanding open situation pavilion, the wind is unlikely to be obstructed (Fig. 2). Orientation is therefore important, so a pavilion could react to the prevailing wind. In terms of temperature, London summers do not reach high extremes and wind for cooling purposes is not an imperative. A sustained wind can be uncomfortable for occupants, but questionnaires revealed no complaints of draft or overheating. For Gehry’s pavilion the detrimental effect of wind was not related to operative temperature changes causing discomfort, but rather by the wind in conjunction with rain causing water to fall into the pavilion, making certain seats and occupants wet. Open only during the summer months, calculations show that there was a summer cooling effect of 2.6 K with spot measured wind speeds of 0.7 m/s. Occupants were also comfortable in wind speeds above 2.0 m/s. This is important because 74% of the time that the Serpentine pavilion is open, wind speeds are above 2.0 m/s and spot measurements showed little to no difference in interior/exterior wind speeds (Fig. 2). Of the 74%, 15% of the time wind speeds were greater than or equal to 6.0 m/s, which would be uncomfortable and according to Penwarden [10]. Total protection from wind speeds at or above 6.0 m/s would probably not need to be a design priority, as more than 98% of the time the pavilion has an open program and people would either not come or leave the park when wind speeds are that high. 3.3. Open Program, Open Space Conclusions Free standing pavilions situated in an open space enable the architect to use a device to modulate shading and to choose whether to allow or mediate solar radiation levels. Orientation is the determinant factor of detrimental effects of wind since it is located in an unobstructed open environment. Additionally, wind can also very easily become a compound variable with rain due to the limited protection provided in an open setting.

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Figure 6: Shadow Analysis of Hay’s Galleria after Ecotect v 5.6 [5]

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

4.2. Hay’s Galleria Wind Analysis

5. REDEFINING PAVILIONS

The year-round use of Hays Galleria is a key factor in determining the effects of wind, as occupant needs and criteria vary depending on summer or winter use. The Height-Width ratio also plays a role, by having the potential to change the wind speed and direction Entering the pavilion, there is a 2 K difference in temperature as a result of the wind chill. According to the equation, wind chill does not become a factor until wind speeds are greater than 2.0 m/s [8]. Wind speeds just above 2.0 result in a negligible difference. Inside the Hay’s Galleria the measured wind speed never exceeded 2.0 m/s, but the occupants considered it to be drafty. Essentially, the data analysis shows that even on a windy day, the wind chill is not lowering the temperatures inside Hay’s Galleria, however there is still discomfort for long term occupants. The discomfort may be associated with the human perception of wind. A direct relationship was not found between increased percentage opening of the structure and increased wind speed inside the pavilion, the locations of the openings in relation to occupant use and pavilion form may be more important. In cold climates, contrary to the equation, the effect of wind speed seems to be dependent on how long the occupant is in the space. While the wind chill temperature equation is a function of the outdoor temperature, it appears to apply to short-term visitors. When visitors enter a pavilion, the equation did correlate a less windy environment to a decrease in dT caused by wind, which was noticed by shortterm occupants as an improvement in the environmental condition. Long-term employees were uncomfortable in the same conditions, which does not match the premise of the equation where speeds less than 2.0 m/s caused no change in temperature. The results show that users need to be differentiated in terms of time spent within the pavilion in order to assess subsequent effects of different wind velocities throughout the year. Essentially, in colder climates, long-term occupants were noted to have stricter criteria more attuned to indoor standards of discomfort for cold wind, while short-term occupants have a looser criterion matched more with the outdoor equation for Wind Chill temperature. Summer conditions results suggested that higher wind speeds would be tolerated by both groups of occupants.

A pavilion can exist and function based solely on programmatic features with little reference to environmental factors. However, to reach its full potential in terms of maximizing numbers of occupants and time spent within the structure, pavilions must perform environmentally. In this study, pavilions have been defined by their building characteristics and program use. In conclusion, the study seeks to redefine pavilions according to environmental performance characteristics. Defining pavilions by their environmental performance leads to the question of what should be provided in terms of internal conditions of a pavilion, when can this be expected, and who would be the optimal occupants of the space. To be an environmentally performing pavilion, a structure must influence and/or improve upon the outdoor conditions. Contrary to interior single state standards and ideals, for pavilions establishing concurrent conditions of environmental variation across time and space it is critical to allow for occupant adaptation which relates directly to a widening of the comfort zone and an increase in time spent. Occupants with some degree of freedom of movement and clothing choice would be better suited to take advantage of varying conditions. Extremely strict programs for long periods of time would not be suited to this type of environmental condition. The ability to provide a variation of conditions is determined by the limiting factor of comfort and varies for different climates. If the desired performance of a pavilion is to improve upon the outdoor conditions, pavilions will probably be able exist and function in all climates but not all microclimates. Strictly speaking only in terms of environmental performance, access to the limiting factor of comfort defines to what extent a pavilion can be expected to perform and succeed in improving upon outdoor conditions. In upper latitudes, when temperatures are below comfort, solar radiation is the limiting factor. As a result, environmental performance pavilions must be located in open space. If located in overshadowed urban spaces, the lower solar altitude will inhibit or block all access to the sun. Without solar radiation in colder climates, pavilions cannot provide an environmental function and can even make the conditions worse for occupants. Although not specifically studied in this paper, the limiting factor of lower latitude and warmer climate is hypothesized to be access to wind velocity. Thus an environmentally performing pavilion could potentially exist in urban environments but it must have appropriate wind speeds to cool the space. By defining the limiting factor and environmental performance, a galleria in an upper latitude and cold climate does not meet the requirements of an environmentally performing pavilion. They have proven to be self-shaded yearround, diminishing the limiting factor for environmental modulation. However, the study showed that Hay’s Galleria is occupied, albeit in less

4.3. Strict Program, Urban Setting Conclusions Pavilions within an urban setting are directly dependent on their surroundings. If overshadowed for the majority of the year, important solar gains are severely reduced. Galleria types have an increased potential for total overshadowing through selfshading, a function of its height-width ratio. For general design briefs, pavilions used in the winter for occupants staying longer than 30 minutes need to have more protection from wind than summer pavilions or short term use winter pavilions.

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numbers and for shorter periods of time, in the winter months. Occupants were drawn into the pavilion, in spite of its environmental performance due to its function and spectacle. Elements of spectacle were woven into all pavilions studied. Spectacle can appear in various forms but should be an aspect of a successful pavilion. If success is defined by increased numbers of occupants drawn by conditions outside of basic shelter, spectacle gives a reason for potential occupants to make an unplanned stop at a structure such as a pavilion. By developing pavilions to also function environmentally, architects can extend the period of time spent in the pavilion, thus expanding its functionality.

6. ACKNOWLEDGEMENTS We would like to acknowledge SED course director Simos Yannas and tutors Ruchi Choudhary and Raul Moura for their advice and support. Milena Stojković would like to thank the Government of the Republic of Serbia’s Fund for Young Talents for their financial support.

7. REFERENCES [1] Humphreys, M. and F. Nicol, CIBSE Guide A. Chartered Institution of Building Services Engineers, London 2006, 1-1, 1-15. [2] CIBSE, Comfort, CIBSE knowledge Series KS 6. Chartered Institution of Building services Engineers, London, 2006, 41. [3] METEONORM v.6, Meteotest. Global Database for Solar Energy and Applied Climatology, 2008. [4] Satel-Light, accessed on 12/19/2008 at 12:19 pm, http://www.satellight.com/pub/Cameron12192008121909/soutdo or.htm [5] ECOTECT v.5.6, Square One / Autodesk, 2008. [6] RADIANCE, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, 2000. [7] Auliciems, A., S. Szokolay, Thermal Comfort. PLEA Note 3. PLEA International / University of Queensland, 1997. [8] Arens, E., L. Zeren, R. Gonzalez, L. Berglund, P.E. McNall, A new Bioclimatic Chart for Environmental Design. Proc. ICBEM Conference, Pavoa de Varzim, Pergamon, London, 1980, 645-657. [9] Met Office, 2008 Weather Summaries, http://www.metoffice.gov.uk/climate/uk/2008/ind ex.html [10] Penwarden AD., Acceptable wind speeds in towns, 1973, www.meteorologia.gr

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Thermal Strategies for Economical Dwellings in Warm Dry Climates in Mexico IRENE MARINCIC, JOSÉ MANUEL OCHOA AND MARÍA GUADALUPE ALPUCHE Dpt. Architecture and Design, University of Sonora, Hermosillo, Mexico ABSTRACT: The need for quick and economic construction of housing for low-income populations in Mexico has meant that in any climate, housing developments are designed and constructed without regional adaptation. The city of Hermosillo, in northwest Mexico, has a hot dry climate, but despite this situation, a large number of dwellings are not constructed according to local climate conditions. Field studies have been carried out in order to determine physical characteristics of the houses, social and physical characteristic of the people, electricity consumption, indoor climate variables and asked thermal sensation from the users. Some results of this research, presented in previous publications, show high thermal discomfort levels during most of the year, as well as high electricity consumptions. Federal regulations for thermal design in residential dwelling envelopes are being developed (NOM-020-ENER), but they are still in the draft stage. Although there is information available for designers and developers, thermal strategies are not usually applied in low-cost housing developments. Passive thermal strategies are presented in this article, based on regional needs and economic limitations. They focus more on cooling requirements. Some water conservation suggestions and integrated renewal energy techniques have also been taken into account. Keywords: passive thermal strategies, low-cost dwelling, hot dry climate

1. INTRODUCTION Tract housing has become common in many regions of Mexico. More often than not, the need for quick and economic construction means that dwelling designs are not adapted to local environment and climate conditions, and it is common to observe the same affordable housing models in different climate zones within the Mexican territory. Increasing housing demand drives developers to reduce spaces and utilize fewer materials and labor. The quality of housing in general, and energy-efficient design in particular, are not a priority, and this results in excessive energy use and high acclimatization costs. Within the framework of a research project titled Thermal comfort and energy efficiency in low-cost dwellings in Mexico: regions of warm dry and warm humid climates, supported by federal funding, several surveys were carried out which measured thermal comfort and energy use in low-cost housing in seven Mexican cities with hot dry and hot humid climates. Field studies yielded a database which shows the impact of housing design solutions on thermal comfort and electricity consumption due to acclimatization in very hot environments. This article proposes passive thermal design strategies, specific

to local needs and climate, while taking into account economic considerations. This type of research contributes to the knowledge base which supports actions aimed at reducing electricity consumptions, which greatly impacts the housing sector, particularly for lowincome populations, considering the large number of dwellings being constructed in cities like Hermosillo, and in Mexico in general.

2. LOCAL CLIMATE AND AVAILABLE HOUSING

LOW-COST

2.1. Climate The climate in Hermosillo is characterized by very high levels of solar radiation, clear skies throughout the year and large temperature oscillations daily and seasonally. The hot season is very prolonged (5-6 months), with daily temperatures between 25-30 °C and 40-45°C. The coldest season has a mild climate, with daily minimum temperatures of 0 to 7°C and maximum temperatures of 25 to 30°C. Relative humidity is very low during practically the entire year. Considering the climate is so harsh, architectural design criteria and application must be adapted stringently to environmental conditions in order to minimize the negative climate effects on occupants and their energy consumption.

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2.2.

Low-cost dwellings

The dwellings studied are part of a government program for families with a monthly income of between 100 and 400 €. The price of each dwelling is approximately 11723 €. They are one-story homes 2 with a constructed area of between 33.5 m and 39 2 m according to the model, on a lot with an area 2 which varies between 117 and 122 m . They have one bedroom, a combined living room-dining roomkitchen area and one bathroom, as well as an outdoor garage (Fig. 1, 2 and 3). Construction of these dwellings is very costeffective: walls are made of cement blocks in almost all cases, with joist slabs and polystyrene vaults, no insulation, and no solar protection devices on the windows.

Figure 3: Floor plan for a low-cost housing model.

3. THERMAL COMFORT WITHIN DWELLINGS Figure 1: Tract housing development on the outskirts of Hermosillo, Mexico (Google Earth)

Figure 2: Typical facade of a low-cost housing model.

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3.1. Field surveys Nine low-cost housing developments in Hermosillo constructed between 2002 and 2005 (Figs. 1, 2 and 3) were studied, which constitutes practically the total number of developments handed over to the municipality with full services and at least one year of inhabitance. Surveys were applied in order to study different aspects of the dwellings and their occupants. One survey focused on recording the physical characteristics of the homes, as well as establishing a profile of the inhabitants and their perception of the dwelling. The second survey, applied at two different periods of the year, was aimed at recording the thermal sensation of the inhabitants, while at the same time monitoring the thermal conditions within the home (Fig. 4). Subsequently, information was collected on electricity consumption of the surveyed dwellings during the corresponding period.

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3.2. Indoor thermal conditions and electricity consumptions During the thermal sensation surveys, several variables have been measured indoors: air temperature, globe temperature, relative humidity and wind speed. From these variables, may be the most representatives to illustrate the thermal conditions are the air temperature and relative humidity. We have plotted them in two graphs (Figs. 5 and 6) corresponding to winter and summer period surveys. 45

400

Average electricity consumptions per house per month (kWh)

Figure 4: Thermal comfort surveys and indoor thermal variables monitoring.

warm. In summer, indoor temperature is hot. Indoor relative humidity can be considered as low. The use of acclimatization systems by inhabitants is mostly during nights, because they generally work during daytime. Most of the families use evaporative coolers only in the bedroom, and in the rest of the house, fans or nothing. In some cases they use a window air conditioner in the bedroom. In almost all cases the devices are old and inefficient. Electricity consumptions were collected from the surveyed houses during more than one year. In general, according to the characteristics of the local climate, the year can be divided into two climatic periods: approximately a half of the year with hot dry climate (summer period) and the other half year (winter period) is temperate. Intermediate seasons are very short. There is also a differentiation between electricity costs, which received more or less government subsidies, according to these two periods. The cheapest prices are in summer. 350

300

250

200

150

100

40

50

35

Tint (°C)

0 Winter

30

Figure 7: Average electricity consumptions per house per month in winter and summer periods

25

20

15

10 0

10

20

30

40

50

60

70

80

90

100

HR (%)

Figure 5: Relative humidity and air temperature indoors during the winter survey period [1] 45

40

35

Tint (°C)

Summer

Period

30

25

20

At Fig. 7 average electricity consumptions per house per month in winter and summer periods are presented. However, maximal monthly electricity consumptions can easily reach about 700 kWh in the summer period. Considering the average constructed area of each house, the monthly average 2 consumptions are about 4.6 KWh/m in winter and 2 9.6 KWh/m in summer. This represents not only high energy consumptions but expensive electricity bills that poor families must pay for them. In the case of the lowest incomes families, the annual electricity account can reach about 23% of the annual incomes. Electricity consumption in housing sector has particularly greatly impact, considering the large number of dwellings being constructed in cities like Hermosillo, and in Mexico in general. 3.3. Occupants comfort

15

10 0

10

20

30

40

50

60

70

80

90

100

HR (%)

Figure 6: Relative humidity and air temperature indoors during the summer survey period [1]

As seen in the graphs, indoor temperature during winter varies, but can be considered temperate to

Results of the occupants thermal comfort survey will be discussed briefly, though a more extensive description can be found in [1][2][3]. Occupants indoor comfort perception during winter and summer was registered in terms of comfort votes between -3 and +3 on the ASHRAE scale. It should be noted that the inhabitants of these homes, according to survey

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results, have lived in this city for many years and are fully acclimated to the local climate.

Figure 8: Thermal sensation of inhabitants (% of votes) during winter and summer. Percentages are based on the total votes for each period, although they are graphed together for better compression. [1]

As shown in Fig. 8, the winter climate is very benign and the majority of respondents (more than 60%) feels thermally comfortable (vote 0). In contrast, during the summer, thermal conditions are extremely unfavorable, which is expressed by respondents as a high levels of thermal sensation (from 0 to +3) inside the dwelling. In previous studies [1][2], based on adaptive comfort methods, summer and winter neutral temperatures (Tn) were obtained for this population group. As expected for a desert climate, wide comfort ranges and high neutral temperatures are obtained, compared with reported values of cooler climates (see Table 1). Neutral temperature and limits of comfort range were obtained by the method of statistical regression by layers, proposed by Nicol [4] for “asymmetrical” climates. Table 1: Comfort temperatures obtained for the city of Hermosillo among occupants of low-cost housing.

Period

Winter (mild) Summer (hot)

Upper comfort limit (°C)

Tn (°C)

Lower comfort limit (°C)

23.5

26.9

31.3

29.6

32.2

34.7

Considering the high levels of discomfort, despite the thermal adaptation of the population to the local climate and the high neutral temperatures, thermal design strategies are proposed (based on classic literature [5]) which take into account climate conditions, the adaptation of inhabitants to the local climate, regional customs and economic limitations.

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4. THERMAL DESIGN STRATEGIES FOR LOW-COST HOUSING An Official Standard for the thermal design of residential building envelopes (NOM-020-ENER) [6] was developed for Mexico, but for years it has languished as a draft and has yet to be implemented. Nonetheless, there is sufficient public information available to housing developers and designers (CONAVI guidelines [7]), though the suggested strategies in most cases are not applied in affordable housing developments. Therefore, it is necessary to propose specific and local design strategies and disseminate them among multiple stakeholders. The following are thermal design strategies for low-cost dwellings in one-story tract housing developments, which are prevalent locally due to the availability of land (though they may not be ideal in terms of cost). Though these strategies focus on thermal aspects, lighting and water-management considerations are included, since these issues are relevant to local conditions. Integration of solar energy systems is also included, considering the availability of solar radiation in the region. We have included illustrations with basic explanations for a comprehensive document for all users. More extended and complete design guidelines will be included in a book which is currently in press. In addition, several local events have been organized in order to disseminate these ideas among developers, members of professional organizations, and local officials, among others. 4.1. Urban design strategies Urban design strategies (Table 2) are generally intended to make public and private outdoor spaces more pleasant in order to improve habitability and decrease the thermal load towards the dwelling. Table 2: Urban design strategies

Urban design strategy

Construction and design solution Compact grouping Separation which favors shading between dwellings

Promote the habitability of outdoor spaces and decrease heat exchange towards dwellings

Spaces which promote microclimates Urban layout for N-S orientation of facades Outdoor solar protection devices and deciduous vegetation (low-water trees) Perennial vegetation barriers against cold winds

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Decrease dust dispersal, albedo and glare Favor aquifer replenishme nt

Groundcover using lowwater vegetation

Provide thermal inertia to reduce temperature amplitude

Surface materials with moderate reflectance and low emittance

Permeable floors

The architectural design strategies (Table 3) seek to favor the habitability of indoor spaces, decreasing thermal gains, favoring heat loss, and reducing wide temperature oscillations. In order to do this, thermal insulation and high thermal mass are good options. Ventilation is not favorable except at nights during intermediate seasons due to the high temperatures, even at night, and the proliferation of dust. Table 3: Architectural design strategies

Architectur al design strategy Minimize heat gains in general

Provide solar protection devices for windows and walls

Minimize conduction gains

Construction and design solution Compact shape N-S preferent orientation of facades E and W location of service areas Solar protection devices in N and S openings

Icon

Natural convection through zenithal openings Evaporative cooling systems

Decrease heat exchanges by infiltration and dust entry via enclosures Optimize daylighting in perimetral zones and allow penetration of light indoors More efficient artificial lighting

Minimize openings on E and W facades Recessed windows Deciduous leaf vegetation on critical walls Thermal insulation on critical roofs and walls (S, E and W) Low absorption and high emittance finishes on building envelope Flexible (mobile) insulation for windows, according to season and day-night periods

Openings for crossventilation only during spring and fall nights High roof emissivity

Favor nocturnal heat loss

4.2. Architectural design strategies

Both sufficient heat capacity and thermal insulation in building envelope and indoor spaces

Optimize water consumption

Urban electricitysolar energy hybrid system Usage of solar-gas hybrid hot water system

Good quality enclosures Sealing devices on doors and windows

Properly sized, shaped and located windows Light-colored finishes on ceilings and walls Low-consumption luminaires (low energy consumption, low heat emission) Greywater recycling system Rainwater collection Drip irrigation in outdoor spaces Low-water vegetation Photovoltaic cells for low-power applications

Flat solar collectors for sanitary hot water

Although some of these strategies require relatively low investment and more creativity of the designer, others such as the integration of renewable energy techniques would require government subsidies or fiscal incentives.

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5. CONCLUSION

7. REFERENCES

The state of low-cost housing and its respective energy and habitability issues is a complex topic, influenced greatly by economic factors, particularly the price limits needed to ensure low-income populations have access to affordable mortgages. This consequently impacts the quality of low-cost dwellings, which is diminished to the point of being unreasonable. Key issues to address for possible solutions must include greater regulation of energyrelated aspects in buildings, as well as a revision of the loan programs available for low-income buyers and the possibility of fiscal incentives for energy generation and energy savings in dwellings. It is also necessary to promote the application of specific and locally relevant strategies among housing developers and all levels of government, as well as homeowners. In low-cost housing, where the majority of inhabitants do not have access to artificial air conditioning, the application of passive thermal design strategies is particularly important and can help bring indoor spaces closer to thermal comfort conditions, as well as promote the conscious use of energy resources used for cooling.

[1] Marincic, I.; Ochoa, J. M.; Alpuche, M.G. and Gómez-Azpeitia, G. Adaptive Thermal Comfort in Warm Dry Climate: Economical Dwellings in Mexico. Proc. 26th Conference on Passive and Low Energy Architecture PLEA 2009. Quebec, Canada (2009), pp. 510-515. [2] Gómez-Azpeitia, G. et al. Comfort temperatures inside low-cost housing. Proc. 26th Conference on Passive and Low Energy Architecture PLEA 2009. Quebec, Canada (2009), pp. 498-503. [3] Romero, R. et al. Thermal comfort and occupant perception in dwellings for the low-income sector in hot climates of Mexico. Proc. 26th Conference on Passive and Low Energy Architecture PLEA 2009. Quebec City, Canada (2009) (2.3.22). [4] Nicol, F. Thermal comfort. A handbook for field studies toward an adaptive model. London, University of East London, 1993. [5] Givoni, Baruch. Climate considerations in building and urban design. USA, John Wiley & Sons, 1998. [6] NOM-020-ENER, http://www.her.itesm.mx/cae/Ligas/Normas/Ante proyecto-NOM-020-ENER.pdf [7] CONAFOVI (now CONAVI), Guidelines for energy efficiency in dwellings (Guía para el uso eficiente de la energía en la vivienda), Mexico, 2006.

6. ACKNOWLEDGEMENTS The project "Thermal comfort and energy efficiency in low-cost dwellings in Mexico: regions of warm dry and warm humid climates" and the field surveys were supported by federal funding from Mexico´s National Housing Commission (CONAVI) and the National Council of Science and Technology (CONACyT). The research has been also supported by CONACyT and the German Federal Ministry of Education and Research (BMBF) in the project Proclima II. The results are also part of the project CB2006/59386, supported by the Mexican Research Found for Education and CONACyT.

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ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. ISBN xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

Subjective Thermal Comfort in Urban Spaces in the Warm-humid City of Guayaquil, Ecuador Erik JOHANSSON1, Moohammed Wasim YAHIA1 1

Housing Development & Management, Lund University, Lund, Sweden

ABSTRACT: The quality of urban spaces is important for ecological, economical and social purposes. The thermal environment in the outdoors affects both energy use and human health. Mental and physical performance is reduced at high temperatures and that is especially a problem in tropical climates. This paper deals with human comfort in the warm-humid city of Guayaquil, Ecuador. The outdoor thermal comfort was assessed through 537 interviews which were conducted in four different places of the city during both the dry and wet seasons. The subjective comfort votes were compared with the physiologically equivalent temperature (PET) which was calculated based on microclimate measurements. The results show that local people accept thermal conditions which are above acceptable comfort limits in temperate climates. The results also show that the subjective thermal perception varies within a wide range. It is clear, however, that the majority of the people in Guayaquil experience the outdoor thermal environment during daytime as too warm and therefore it is important to promote an urban design which creates shade and ventilation. Keywords: Ecuador, microclimate, outdoor thermal comfort, warm humid climate.

1. INTRODUCTION Cities are getting increasingly hotter which has adverse effects on health and well-being of urban dwellers. The problem is especially serious in tropical climates. Studies in the warm-humid climate of Colombo, Sri Lanka have shown that the outdoor environment is very uncomfortable during daytime, especially between 11:00 and 16:00 [1,2,3]. However, these studies were based on calculated thermal comfort and did not include the subjective thermal comfort of the local population. Subjective outdoor thermal comfort has received increased attention the latest decade [4,5,6,7,8]. The outdoor thermal environment is complex and there are large temporal and spatial variations. It has been found that outdoors the thermal comfort range is wider than indoors, spanning from thermal comfort to a stressful environment [4]. Thermal adaptation – which can include physiological, psychological and behavioural factors – has proven to play an important role in subjective thermal comfort assessment [4,6]. There have been few studies on outdoor thermal comfort in urban areas in warm-humid climates. However, in Taiwan, which has warm-humid summers, Lin [6] found evidence of thermal adaptation since the comfort (neutral) temperature proved to be higher than for temperate climates. This paper deals with subjective human comfort in the warm-humid city of Guayaquil, Ecuador. The main aim is to examine the influence of outdoor urban microclimate on people’s subjective perception of thermal comfort and to compare it with the physiologically equivalent temperature (PET). The aim is also to compare the thermal perception between the dry and the wet seasons.

2. GUAYAQUIL AND ITS CLIMATE Guayaquil is the largest city of Ecuador with about 2.4 million inhabitants. The city is situated at

sea level near the equator at latitude 2.11°S and longitude 79.53°W. Guayaquil’s historical centre was established during the Spanish colonial time to the west of the Guayas river and it is laid out in a regular grid iron street pattern. Due to marshlands in the west and the river in the east the city has grown mainly to the north and to the south. Temp.‐mean max

Temp.‐mean min

RH‐max

RH‐min

°C 32.5

% 100

30.0  

80

27.5

60

 

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40

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0 J

F M A M J

J A S O N D

Figure 1: Climate of Guayaquil.

As the rest of the coastal zone of Ecuador, Guayaquil has a warm humid climate. Precipitation, however, is limited to the period December to April. Nevertheless, the humidity remains high all year round due to the proximity to the Pacific ocean. The climate is very stable over the year with daily mean maximum temperatures of 28–30°C and minimum mean temperatures of 21–24°C (the higher values occur during the rainy season). The daily mean relative humidity is around 70% during the dry season and 75% during the wet season. See Fig. 1. The wind speeds are low, especially during the rainy season; monthly averages range from 1.5 to 3.2 m/s. Thermal comfort is poor due to a combination of high

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temperatures, high humidity and low wind speeds. The situation is worsened by the solar radiation; in spite of a high amount of cloud cover there are periods of clear skies, even during the rainy period. The rainy season has the worst thermal conditions since both temperatures and humidity are higher.

Table 1: The studied locations as well as the dates and times for the field campaigns.

Place

Description

Parque Centenário

Centrally located public park Waterfront recreational area

Malecón 2000

 

(a)

(b)

(d) Figure 2: The locations of the field campaigns: (a) Parque Centenário, (b) Malecón 2000 waterfront, (c) neighbourhood square in Mucho Lote and (d) arcade along Bulevar Nueve de Octubre.

3. FIELD CAMPAIGNS Both micrometeorological measurements and a questionnaire survey were conducted during the dry season (June 2009) and the wet season (March– April 2010). 3.1. Studied locations The field campaign took place in four areas in Guayaquil and included three open, public places and one avenue. Three of the areas – a public park, a waterfront area and a street canyon – were in the city centre whereas the fourth site consisted of a small neighbourhood square in the newly built suburb Mucho Lote in the north of the city. The studied locations are shown in Fig. 2 and are described briefly in Table 1. 3.2. Microclimatic measurements Most of the field campaigns took place between 11:00 and 16:00, i.e. during the hottest period of the day. This is also the period when the studied sites had the most visitors. In order to include cooler weather conditions, measurements and interviews were also carried out in the evening on one occasion during the dry season. The dates and the times of each field campaign are described in Table 1. The field campaigns took place during clear, partly cloudy and overcast weather conditions. Rainy days were excluded from the study.

 

2

578

Time

15.06.09 18.06.09 05.04.10 16.06.09 24.06.09 25.06.09 06.04.10 Newly built 19.06.09 residential 25.06.09 area 31.03.10 Main 26.06.09 avenue, N-S 07.04.10 oriented

11:10–12:10 11:50–13:05 14:50–15:50 11:30–12:30 13:50–15:10 18:30–19:40 14:40–15:40 14:20–15:30 13:30–14:30 14:10–15;20 13:30–14:30 12:50–13:40

Four micrometeorological variables that affect thermal comfort were measured: air temperature (Ta), relative humidity (RH), globe temperature (Tg) and wind speed (va). The type of sensors and their accuracy are shown in Table 2. The sensors were connected to a data logger (Campbell CR800) on which 1-minute averages were sampled.

(b) (c)

(c)

Small square, Mucho Lote Bulevar Nueve de Octubre

Date

Table 2: Measurement equipment and its accuracy. (Ta = air temperature; Tg = globe temperature; RH = relative humidity; va = wind speed.)

Variable Ta RH Tg va

Sensor Rotronic Hydroclip S3 Rotronic Hydroclip S3 AMR Pt100 PK 24 Gill windsonic anem.

Accuracy ±0.3°C ±1.5% RH ±0.3°C ±2% @ 12 m/s

                            Figure 3: The measurement sensors mounted on a camera tripod and connected to the data logger.

The sensors were mounted on a camera tripod, see Fig. 3. The measurements were taken at the height of 1.1 m, except for the wind speed which was measured at 1.5 m height. The temperature and relative humidity sensor was covered by a white, naturally ventilated radiation shield. The corresponding wind speed at 1.1 m was calculated as [4]: ͳǤͳ݉ ‫ן‬ ൰ ‫ݒ‬ଵǤଵ ൌ ‫ݒ‬ଵǤହ ൈ ൬ ͳǤͷ݉

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Where v1.1= wind speed at 1.1 m, v1.5 = wind speed at 1.5 m and α is the mean speed coefficient which depends on the roughness of the ground (e.g., α = 0.24 for parks and suburbs and α = 0.28 in the centre of large cities). The mean radiant temperature (MRT) considers both short-wave and long-wave radiation and represents the weighted average temperature of an imaginary enclosure that gives the same radiation as the complex urban environment. In this study, MRT was derived from the globe temperature and the wind speed, and it was calculated using the formula developed by [9]: ����� � ��� �� ���� ����� � ��� � �� ������ � ������

��� � ���� � �������� �

where Tg = the globe temperature (°C), va = the air speed (m/s), Ta = the air temperature (°C), D = the globe diameter (mm) and ε = the globe emissivity. The globe thermometer consisted of a flat grey painted table tennis ball. Its diameter, D, was 38 mm and its emissivity, ε, was assumed to be 0.97. It should be noted that the MRT calculated in this way is very sensitive to variations in wind speed. E.g. an increase in wind speed will mean that the globe cools down and Tg decreases, but as this will take some time to happen, MRT will be overestimated. Similarly a sudden decrease in wind speed will lead to an underestimated MRT. To reduce the sensitivity to wind speed variations, 10 minute averages of wind speed were used in the calculations of MRT. The measurement equipment was placed near places where people pass by. At the three open public sites the globe thermometer was exposed to solar radiation during the entire measurement campaign. At Bulevar Nueve de Octubre, however, the globe thermometer was in shade under an arcade. The measurement equipment used is shown in Table 2. 3.3. Thermal comfort investigation The questionnaire survey to estimate the subjective thermal comfort was performed simultaneously with the measurements at each location. The questionnaire was in Spanish and apart from thermal sensation it included questions regarding gender, age, type of clothing, reasons for being in the places, time spent outdoors as well as whether the subjects had air conditioning at home and in their office/school. This paper, however, discusses only the results related to subjective thermal comfort. The subjects were asked to report their thermal sensation on a 9point scale: very cold (-4), cold (-3), cool (-2), slightly cool (-1), comfortable (0), slightly warm (+1), warm (+2), hot (+3), and very hot (+4). The reason for using a 9-point scale instead of the commonly used 7-point scale was to link the results to the thermal sensation scale of the PET thermal comfort index [5], see Table 3. It was emphasized by the interviewers that it was the subjects’ sensation at the moment of the interview that was requested and not their

general opinion. In addition the subjects were asked about their thermal preference on a 3-point scale. They were asked whether they would like it to be: “cooler, no change or warmer?” as well as if they would like: “More sun, no change or more shade?”, “More humidity, no change or less humidity?” and “more wind, no change or less wind?”. Table 3: Thermal original sensation scale of the PET index [5].

PET (°C) <4 4-8 8-13 13-18 18-23 23-29 29-35 35-41 >41

Thermal Sensation Very cold Cold Cool Slightly cool Comfortable Slightly warm Warm Hot Very hot

Stage of Stress Extreme stress Strong stress Moderate stress Slight stress No stress Slight stress Moderate stress Strong stress Extreme stress

The subjects were interviewed as close to the measurement equipment as possible. This means that the subjects were exposed to solar radiation (if the sky was not overcast) at all sites except Bulevar Nueve de Octubre where the interviews took place in shade of the arcade, see Fig. 2. However, also at the “exposed” sites a limited number of subjects were interviewed under shade (trees) a little bit farther away from the equipment. The reason was that people preferred staying in the shade on clear sky conditions. The questionnaire survey was conducted by the author and students of the Catholic University of Guayaquil. Each interview took about three minutes to complete. About 30 to 50 questionnaires were answered at each field campaign. In the dry season there were two campaigns at each site and in the wet season one per site. A total of 358 questionnaires were answered during the dry season and 179 during the wet season. The two samples were similar in terms of gender and age distribution. About 35% of the respondents were women and 65% were men. The Interviewed subjects were young in general; the largest age group was 21–35 years (35%) followed by 36–50 years (27%). 3.4. Calculated thermal comfort In this study, thermal comfort was assessed using the physiologically equivalent temperature (PET). The PET, which is based on a steady-state heat balance equation of the human body, is defined as the air temperature at which the energy balance for typical indoor conditions is balanced with the same mean skin temperature and sweat rate as calculated for the complex outdoor conditions [5,6]. Table 3 shows the thermal sensation scale of the PET index. The PET index has been used widely in recent research in outdoor thermal comfort [2,5,6,8]. Thus the PET index was used in this study and was calculated using the PC application RayMan [10].

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

% 

4. RESULTS AND DISCUSSION 4.1. Subjective thermal comfort The subjective comfort votes for the dry and wet seasons are shown in Fig. 4. In order to make a comparison between the seasons possible, Fig. 4 does not include field campaigns where the maximum PET was below 36°C, i.e. Bulevar Nueve de Octubre (under shade), the 18 June 2009 (overcast sky and therefore low PETs) and the evening measurements of the 25 June 2009. For the campaigns included in Fig. 4, PET values ranged from 30 to 52°C. The numbers of included subjects were 172 and 125 in the dry and wet seasons respectively. % 40 35 30 25 20 15 10 5 0

   

Dry season

                       

Wet season

(b)

(c)

It can be seen in Fig. 4 that the people of Guayaquil perceive the daytime outdoor climate as uncomfortable (64% and 88% in the dry and wet seasons respectively), at least when the sky is clear or partly cloudy as was the case for the campaigns included in Fig. 4. The votes however vary considerably from one person to another and range from “slightly cool” (-1) to “very hot” (+4). A similar wide spread of votes have been found in other studies [7,8]. According to the results the wet season is more uncomfortable than the dry season, which was to be expected. It should be noted, however, that the difference found between the wet and dry seasons might have been strengthened by the fact that – in spite of selecting similar days in both seasons – the field campaigns of the wet season had higher PETs. Fig. 5 shows the preference votes as regards temperature, sun/shade, humidity and wind for the same sample as in Fig. 4. It is clear that most people want it to be cooler and they want more shade, less humidity and more wind. This tendency is more pronounced in the wet season. The tendency found here was stronger than for the summer of Sydney [4] and for the summer of Taiwan [6], which indicates that the climate of Guayaquil is really harsh.

 

4

  %    100   80   60   40   20    0     %  100   80   60   40   20    0

Figure 4: Subjective comfort votes on clear and partly cloudy days for the dry season (n=172) and wet season (n=125).

580

100   80   60   40   20    0 (a)

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  %    100  80  60  40   20    0

(d)

Dry season Wet season

Warmer

No change

Colder

Dry season Wet season

More sun

No change

More shade

Dry season Wet season

More hum.

No change

Less hum.

Dry season Wet season

More wind

No change

Less wind

 

Figure 5: Preference votes regarding (a) temperature, (b) sun/shade, (c) humidity and (d) wind on clear and partly cloudy days for the dry season (n=172) and the wet season (n=125).

4.2. Relationship between PET and comfort votes The relationship between the PET index and the subjective comfort votes are shown in Fig. 6 for both the dry and wet seasons. All field campaigns are included and the total number of votes was 537. It can be seen in Fig. 6 that there is a tendency of decreased thermal comfort with increasing PET. Similar relationships have been found by [7,8]. The slopes of the linear regression lines are not very steep. In general both seasons follow the same pattern, however, during the dry season the regression line has a steeper slope. It should be notified that the wet season consisted of only 179 subjects. Another reason for the discrepancy

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011 th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

between the seasons could be that the dry season included colder periods (evening) and thereby a larger range of PETs. The relationship between subjective comfort votes and PET is probably not linear; other studies have shown that there is a difference between colder and warmer seasons [6,8]. It seems that for high PETs there is no distinct pattern, i.e. the regression line tends to be more horizontal. It might also be that people feel less comfortable during the wet season and that this affects their votes (i e their votes are “general” rather than what they felt at the moment of the interview).

        Comfort    vote   4  3  2  1  0  ‐1   ‐2   ‐3   ‐4     22 24 26 28 30    

%

Comfort votes

PET

40  35  30 25 20 15 10

Comfort vote ‐ dry season

5

Comfort vote ‐ wet season

0

Linear (Comfort vote ‐ dry season) Linear (Comfort vote ‐ wet season)

      Figure 7: Frequency distribution of subjective comfort votes and calculated PET (according to Table 3) for the whole sample (n=537).

4.4. Thermal adaptation

32 34 36 38 40 42 44 46 48 50 52 PET (°C)

Figure 6: The relationship between the PET index and the subjective comfort votes including all field campaigns of the dry season (n=358) and the wet season (n=179). (4 = very hot, 3 = hot, 2 = warm, 1 = slightly warm, 0 = comfortable, -1 = slightly cool, -2 = cool, -3 = cold and -4 = very cold)

Fig. 7 shows a comparison between subjective comfort votes and calculated PET index (grouping the PET results according to Table 3). It is clear from Fig. 7 that the actual comfort votes and the calculated thermal comfort do not coincide at all. This is not in agreement with a study during the spring in Tokyo, which has a more moderate climate, where a fairly good fit between subjective and calculated thermal sensation was found [5]. In the case of Guayaquil, however, people tend to accept much higher PETs. 4.3. Clothing The clothing insulation varied between 0.2 and 0.9 clo with an average of 0.50 clo for the whole sample. The most typical clothing ensemble was short-sleeved shirt, long trousers and shoes which corresponds to 0.48 clo. No difference in clothing between the dry and the wet seasons was found. The clothing insulation was rather high because people tend to use a rather conservative dress code with long trousers and sometimes even long-sleeved shirts. Nevertheless, the amount of clothing was lower than found during the warm humid summer in Taiwan (around 0.6 clo) [6].

The fact that about 37% of the subjects perceived the climate as “comfortable” (Fig. 7) although the PET varied between 23°C and 51°C shows that the people of Guayaquil is thermally adapted to the local climate. Some behavioural adaptation was also observed. E.g., during strong sunshine people in public places was seeking shade, either under trees or man-made shading devices. Moreover, some people, especially women, sometimes used a parasol to protect themselves against the solar radiation. Similar adaptive behaviour was found by Lin [6] in Taiwan.

5. CONCLUSIONS This study examined the influence of urban microclimate on people’s subjective thermal perception in the warm-humid city of Guayaquil. It can be concluded that people perceive the climate as uncomfortably warm (62%) and in both the dry and wet seasons people wants more shade (77% and 93%, respectively) and more wind (60% and 68%, respectively). It can also be concluded that the original thermal sensation scale of PET (see Table 3) for a temperate climate is not applicable as an indicator to the warm humid climate of Guayaquil; the local population accept much higher PETs. In order to use the PET as an indicator of thermal comfort, the scale of the index needs to be adjusted to the local climate. The results of this study have urban design implications. Daytime human comfort can be enhanced in public spaces by urban form manipulation [3]. Such an approach could be coupled with the use of solar energy for buildings, where solar collectors and solar cells are applied on e.g. shading devices. Shading at street level is a function of street orientation as well as building height and distances

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between buildings: higher buildings and/or shorter distances between them will increase shade. Additional shading devices, e.g. arcades, overhead shading devices or shading trees are necessary to provide shade around solar noon when angles of the sun are high. Some existing examples in Guayaquil are shown in Fig. 8. Care should however be taken to promote ventilation at building and neighbourhood scales, which is necessary for urban comfort, air quality and indoor thermal comfort. This includes taking the prevailing wind directions into account, the use of straight, wide streets and variation of the building heights.

       

a

b

 

       

c

Figure 8: Existing examples of overhead shade in Guayaquil, (a) arcade, (b) overhead shading device and (c) shading trees.

6. FUTURE STUDIES Further analyses will be made to adjust the thermal sensation scale of the PET index to the local climatic conditions of Guayaquil. In order to develop solutions for enhancing the microclimate in Guayaquil, future studies will also deal with simulations of urban microclimate in which different shading and ventilation options will be studied.

7. ACKNOWLEDGEMENTS This research was supported by the Swedish International Development Cooperation Agency – Sida. The author is most grateful to those students of the Architecture faculty at Universidad Católica de Santiago de Guayaquil who assisted in the questionnaire survey.

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8. REFERENCES [1] R. Emmanuel and E. Johansson (2006), Influence of urban morphology and sea breeze on hot humid microclimate: the case of Colombo, Sri Lanka, Climate Research, 30: 189–200. [2] E. Johansson and R. Emmanuel (2006), The influence of urban design on outdoor thermal comfort in the hot, humid city of Colombo, Sri Lanka, Int. J. Biometeorol., 51:119-33. [3] R. Emmanuel, H. Rosenlund and E. Johansson (2007), Urban shading – a design option for the tropics? A study in Colombo, Sri Lanka, Int. J. Climatol., 27: 1995-2004. [4] J. Spagnolo and R. de Dear (2003), A field study of thermal comfort in outdoor and semi-outdoor environments in subtropical Sydney Australia, Building and Environment, 38: 721-38. [5] S. Thorsson, T. Honjo, F. Lindberg, I. Eliasson and E.-M. Lim (2007), Thermal comfort and outdoor activity in Japanese urban public places, Environment and Behavior, 39: 660-84. [6] T.-P. Lin (2009), Thermal perception, adaptation and attendance in a public square in hot and humid regions, Building and Environment, 44: 2017-26. [7] E. L. Krüger and F. A. Rossi (2010), Effect of personal and microclimatic variables on observed thermal sensation from a field study in southern Brazil, accepted for publication in Building and Environment. [8] M. W. Yahia (2010), Thermal comfort and outdoor urban spaces in a hot dry climate – The city of Damascus, Syria, submitted to Building and Environment. [9] S. Thorsson, F. Lindberg, I. Eliasson and B. Holmer (2007), Different methods for estimating the mean radiant temperature in an outdoor urban setting, Int. J. Climatol., 27: 1983-93. [10] www.urbanclimate.net/rayman/

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Comparison of the EN 15251 and Ashrae Standard 55 adaptive thermal comfort models in the context of a Mediterranean climate Astrid ROETZEL1, Aris TSANGRASSOULIS2, AIKATERINI DRAKOU2, GUSTAVO DE SIQUEIRA3 1

School of Architecture and Building, Deakin University, Geelong, Australia 2 Department of Architecture, University of Thessaly, Volos, Greece 3 Department of Architecture, HafenCity University Hamburg, Germany

ABSTRACT: Strong heat waves in the past decade and resulting legal cases which gave full responsibility for indoor thermal comfort to building professionals lead to an increased uncertainty how to maintain thermal comfort in offices without the use of a cooling system. Adaptive thermal comfort standards such as EN 15251 and Ashrae Standard 55 provide methodologies to evaluate comfort in naturally ventilated spaces. Based on a parametric study for a typical cellular office in the context of Athens, Greece, and using the building simulation software EnergyPlus, this study investigates the potentials for the applicability of natural ventilation in a Mediterranean climate. The Ashrae Standard 55 and EN 15251 adaptive thermal comfort models are compared in this context, and conclusions are drawn how the use of natural ventilation based on adaptive models can be further encourgaged. Keywords: adaptive thermal comfort models, comfort limits, exceeding criteria, occupant behaviour, weather data

1. INTRODUCTION After the occurrence of strong heat waves in the past decade in Europe and predictions for further temperature increase, the question how to maintain comfortable temperatures without increasing related greenhouse gas emissions has become a major challenge for building professionals. This refers especially to office buildings in warm climates, where internal heat gains tend to be high and occur at the same time with solar heat gains. For naturally ventilated buildings, adaptive thermal comfort standards like EN 15251 [1] and Ashrae Standard 55 [2] provide a method to evaluate the acceptability of room temperatures. They are based on field studies in real buildings [3, 4] and relate comfort limits to feedback from the outside climate. When the adaptive comfort criteria cannot be met, the evaluation according to a static model is recommended, which implies the use of an additional cooling system. Due to legal cases where building professionals have been given full responsibility for overheating, a tendency towards an installation of cooling systems can be observed in the past decade. Nevertheless it remains unclear in how far this is predominantly a measure towards legal safety rather than a question of comfort. Additionally, in the context of comfort prediction, especially when using building simulation, results are not only depending on building design, but also strongly influenced by the chosen weather data set, and the assumed occupants or tenants and their preferences and behaviour. This indicates that not only building professionals but also occupants have a potential and responsibility for improvement. This study therefore aims to evaluate the influence of building design, occupants and local climate variability on adaptive thermal comfort in

naturally ventilated offices. It is based on a parametric study for a typical cellular office room in the context of Athens, Greece, using the building simulation software EnergyPlus. For thermal comfort evaluation this study compares the two adaptive thermal comfort models which can be applied in Greece. EN 15251 to which the national building code refers for thermal comfort evaluation in public buildings and Ashrae Standard 55 which is applicable world-wide. Conclusions are drawn how the use of natural ventilation can be encouraged in Mediterranean climates, through the application of adaptive thermal comfort models.

2. SIMULATION MODEL 2.1. Weather data for Athens, Greece Due to the increase of greenhouse gas emissions within the last decades, projections of the Intergovernmental Panel on Climate Change [5] for the 21st century predict a global warming of about 0,2°C per decade for the next two decades. In Greece a sudden increase of the frequency of occurrence of particularly hot days as well as the duration of heat waves was observed [6] within the last decade. This supports indications from literature [7], that common weather data sets, like test reference years, which are based on data from the past, are likely to underestimate of overheating. For this reason weather data sets including climate change scenarios or the heat island effect are desirable, but were not available for the location of Athens. Therefore, based on measured temperature data for the average year 2005 and the hot year 2007 related weather data sets have been generated using the software Meteonorm [8]. Both years are representative for the past decade, 2005 reflecting a

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

typical year and 2007 a hot year with three major heat waves. 2.2. Building design The investigated office room is a typical cellular office in Athens, Greece, with a room depth of 5,4m, a facade width of 3,5m and a room height of 2,7m. The facade is facing south, with a centrally located top hung window which can be manually operated by occupants. For this basic configuration three different building design variations have been developed in order to reflect different priorities on the real estate market (table 1): The “prestige” variation follows current architectural fashion, with the fully glazed facade and internal shading as a symbol for a transparent company policy. Low-e glazing improves solar protection, light internal walls provide reversibility of the floor plan, and a false floor construction flexibility regarding furnishing. A suspended acoustic ceiling provides acoustic comfort and an advanced lighting system supports the representativeness of the interior and contributes to the luxury level of the office. The “low cost” variation is designed to provide maximum profit for rent or sale on the real estate market. Initial costs are kept to a minimum, by using a solid instead of a curtain wall facade, standard instead of low-e glazing, a standard instead of an advanced lighting system, and screed instead of a false floor construction. Light internal walls provide both, low initial costs and reversibility of the floor plan, and a suspended acoustic ceiling provides acoustic comfort. The “green” variation is designed to improve thermal as well as visual comfort and reduce the related energy consumption and running costs to a minimum. An overhang, external shading system and low-e glazing provide protection from solar heat gains, and a large window area allows for high daylight levels.

An advanced lighting system is used to minimise energy consumption. A solid facade, solid internal walls, a screed floor and an uncovered ceiling provide maximum mass to increase the thermal robustness of the building. However additional measures to provide acoustic comfort might be necessary and the floor plan is not reversible. 2.3. Technical systems For this study the use as an architectural office is assumed, which requires computer work as well as reading tasks for plans and drawings. Two different room related lighting design variations have been developed for the specific office room using the lighting design software “Relux” [9]. The standard variation has a installed lighting power of 21,3W/m² and the advanced variation of 13,1W/m². Both fulfil the requirements of DIN EN 12464-1 [10]. The heating system assumed in this study is a typical configuration for the Athens context based on natural gas, with a coefficient of performance (COP) = 0,85. 2.4. Ideal and worst case scenario for occupant behaviour In order to emphasize the range of influence of occupants in real buildings a worst case and ideal scenario has been developed for this study. These scenarios differ between parameters on a company and an individual level, based on the use in an architectural office. The ideal scenario represents from comfort and energy point of view the optimum use, the worst-case scenario the least optimized use. The scenarios are described in table 2.

Table 1: Characteristics of the building configurations

Building configurations configuration

1, “prestige”

2, “low initial costs”

3, “green”

Thermal mass

Light

Medium

heavy

Window area Glazing shading overhang Lighting system

100% Low-e internal venetian blind no optimised

20% Standard Interior venetian blind no standard

70% Low-e Exterior venetian blind 1m optimised

2

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 2: Ideal and worst case scenario for occupant’s influence

Worst case and ideal scenario for use of office equipment, ventilation, blinds, and lights Influenced on

parameter

company level

Office equipment

ideal scenario - With notebooks (82W) - possibility to disconnect office equipment from power supply outside office hours (0W) - night ventilation possible

Use of blinds

- blinds closed all day (passive user) - slat angle 10° (no view)

Use of lights

- light on during working hours (passive user)

- blinds opened + closed according to glare or heat protection (active user) - slat angle 45° (limited view) - light on/off according to daylight (active user)

ventilation Level of individual occupants

worst case scenario - With desktop computers (352W) - no possibility to disconnect office equipment from power supply outside office hours (40W) - no night ventilation possible

3. RESULTS 3.1. EN 15251 and Ashrae 55 in comparison Figures 1 to 3 show a comparison of the percentage of working time when the requirements of the different comfort categories according to EN 15251 and Ashrae Standard 55 are met. The comparison shows, that none of the investigated configurations of building design and occupant behaviour meets the comfort criteria in EN 15251 or Ashrae Standard 55. The only exception is the green building in combination with ideal occupant behaviour and the average weather data, which meets the requirements for EN 15251 category III when applying the 5% exceeding criterion.

 

Figure 1: Comparison of different adaptive thermal comfort standards and categories, green variation

The highest percentages of working time meeting the comfort criteria of the standards can be observed for EN 15251 category III for all configurations. Second highest values apply for EN 15251 category II, except for the green building with ideal occupant behaviour when Ashrae Standard 55 with 80% acceptability has a higher percentage of comfortable working time. The third highest percentages of working time meeting the comfort criteria can be observed for Ashrae Standard 55 with 80% acceptability, except for the green building in combination with ideal occupant behaviour. The forth largest percentage of working time when comfort criteria are met can be observed for EN 15251 category I, with the exception of the green building combined with ideal occupant behaviour. And fifth largest or lowest percentages of working time meeting the comfort criteria apply for Ashrae Standard 55 with 90% acceptability, again with the exception of the green building in combination with ideal occupant behaviour. As can be expected, for most building configurations and both comfort standards, the ideal scenario with average weather data lead to highest percentage of working time meeting the comfort criteria, followed by ideal scenario + hot weather data, worst case scenario and average weather data. Lowest percentages occur for the worst case scenario in combination with the hot weather data set. However a deviation can be observed for the green building in combination with ideal occupant scenario. For both weather data sets comfort percentages according to EN 15251 category I are lower than for the worst case scenario (figure 4). This is caused by operative temperatures exceeding the lower comfort limits for low outside temperatures. The largest difference between the ideal and worst case scenario occurs for the low cost building design. This is related to the fact that this variation has a small window in a solid wall, which results in a lower overall thermal transmittance (u-value) for the facade compared to the other variations. When no night ventilation is applied, as for the worst case scenario, this lowers the possibility for cooling of the room by heat exchange via the closed facade.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

When using the hot instead of the average weather data set, thermal comfort percentages decrease up to 13%. The influence of the weather data set is strongest when internal heat loads are low (ideal scenario). Additionally, when night ventilation is not applicable (worst case scenario), the influence of the weather data set is more strongly depending on the level of protection from solar heat gains and the facade insulation. Overall the green building variation has highest percentages of working time meeting the comfort criteria, but is also most sensitive towards weather data changes. 3.2 Exceeding hours and comfort limits

 

Figure 2: Comparison of different adaptive thermal comfort standards and categories, low-cost variation

Apart from the low cost configuration, the green building is more affected by different occupant behaviour than the prestige variation. This is caused by the high level of solar protection which minimizes solar heat gains so internal heat loads (especially office equipment) become the predominant influence.

 

Figure 3: Comparison of different adaptive thermal comfort standards and categories, prestige variation

Figures 1-3 indicate, that all variations are quite sensitive towards changes of the weather data set.

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Figure 4 shows a comparison of the Ashrae Standard 55 and EN 15251 comfort limits over the course of the year, together with the operative room temperatures for the green building with ideal or worst case occupant scenario. For a better readability of the picture, for EN 15251 only the comfort limits of category I and III are shown. The comparison of the comfort limits between Ashrae Standard 55 and EN 15251 reflects the different outside temperature reference in both standards. EN 15251 refers to the exponentially weighted running mean of the daily mean external temperature, and thus reacts to outside temperature changes on a shorter time scale than the Ashrae model, which is reflected in the distribution of the upper and lower limits. The Ashrae 55 adaptive model in contrast is based on the mean outdoor monthly air temperature, which leads to a smoother distribution of temperature limits compared to the EN 15251 model. Another obvious difference between both models is, that upper as well as lower comfort limits according to EN 15251 are significantly higher than those of Ashrae Standard 55. For the investigated climate, the upper limits of EN 15251 category I are in the same ballpark compared to the upper limits of Ashrae Standard 55 with 80% acceptability. And the lower limits of EN 15251 category III are as a first approximation comparable to the lower limits of Ashrae Standard 55 with 90% acceptability. The investigated green building configuration exceeds the comfort limits of both standards mainly in winter and in summer. Compared to Ashrae Standard 55, EN 15251 allows for higher temperatures during summer, whereas Ashrae Standard 55 allows for colder temperatures during winter. It can be concluded, that the fact that comfort criteria are not met, is not only due to overheating in summer, but to a large extent also due to exceeding of the lower comfort limits in winter.  The distribution of the comfort limits for both standards is interesting in the context of the operative room temperatures. Figure 4 shows two sets of operative room temperatures for the green building design, one with an ideal occupant scenario and the other with the worst case scenario. Temperatures for the worst case scenario are approximately 2-3 K higher throughout the year than for the ideal scenario mainly due to different use of office equipment and lighting.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 1315 July 2011 th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

 

 

Figure 4: Distribution of comfort limits for EN 15251 and Ashrae Standard 55 and operative room temperatures for the green building configuration

4. DISCUSSION Section 3 compares the EN 15251 with the Ashrae Standard 55 adaptive thermal comfort model for the climate of Athens, Greece. The comparison shows that is it almost impossible to meet the criteria of the two models for the investigated configurations of building design and occupant behaviour, because comfort limits are frequently exceeded. However this does not only refer to the upper limits and related overheating but to a large extent also to exceeding of the lower limits. Common interpretation of the exceeding criteria however, mainly refers to the upper limits. Thus exceeding hours are likely to be considered overheating hours. Most of the investigated configurations would still not meet the comfort criteria in both models when only the exceeding hours of the upper limits would be taken into account. Nevertheless a separate evaluation of exceeding hours of the upper and lower comfort limits might be helpful for thermal comfort evaluation based on the two adaptive models. Upper limits indicate a risk for overheating, and a possible need for an additional cooling system, whereas the lower limits refer to winter conditions and the use of the heating system. Both adaptive models have been designed to support the application of natural ventilation with focus on summer conditions. However just the number of exceeding hours without a differentiation concerning upper and lower limits might give an incorrect picture of the thermal conditions in summer and could lead to an overestimation of the need for air-conditioning.

Ashrae Standard 55 is supposed to be applicable world-wide and EN 15251 within Europe. Thus both standards can be applied in Greece, however the definition of the range of comfort temperatures in relation to outside conditions differ significantly between both models. As mentioned in the standard, the EN 15251 adaptive model is based on a limited database for temperatures above 25 degrees, so further investigation in a Mediterranean context could be helpful to validate the comfort limits. Especially the lower limits of EN 15251 category I are frequently exceeded for the investigated variations. However a field study [11] indicates that temperatures which the standard considers cool where perceived comfortable in real buildings, so a rethinking of comfort limits for the standard was suggested. Figure 4 illustrates the variability of operative room temperatures depending on the ideal or worst case occupant scenario. The magnitude of variability is significant and could lead to a different comfort classification according to EN 15251 or Ashrae Standard 55 just based on different occupant behaviour. This corresponds with other findings [12], where a significant adaptive resilience of occupants also led to the conclusion that strict temperature standards might be inappropriate and a more flexible evaluation strategy focused on the specific building more suitable. For the green configuration it can be observed, that during winter the worst case scenario with higher internal heat loads is actually beneficial for thermal comfort evaluation due to increased room temperatures caused by heat loads from office equipment and lighting. A large magnitude of variability can also be observed in figures 1-3 for the use of different weather data sets (average vs. hot)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

for the location of Athens. These effects should be considered when evaluating the influence of occupants on thermal comfort evaluation.

5. CONCLUSION Adaptive thermal comfort standards like EN 15251 and Ashrae Standard 55 are a useful tool to evaluate comfort in naturally ventilated buildings and to provide target values for operative temperatures based on field studies in real buildings. This paper addresses some key difficulties concerning the application of the adaptive models:  For the Mediterranean climate in Athens, Greece, it is very difficult to fulfil the criteria of the adaptive thermal comfort models according to EN 15251 and Ashrae Standard 55. In practice it can therefore be legally safer to rely on air-conditioning rather than on natural ventilation. A comment in the standards, how to deal with exceeding hours of different magnitude and to differentiate between exceeding the upper and lower limits could be helpful to support the applicability of natural ventilation in buildings.  The investigated configurations of building design and occupant behaviour led to different comfort classification according to EN 15251 and Ashrae Standard 55. Further validation concerning the comfort limits in a Mediterranean context could be useful.  This study shows, that the percentage of working time meeting the comfort criteria according to EN 15251 or Ashrae Standard 55 varied up to 10% depending on the climate data and up to 30% depending on occupant scenarios. This contradicts with the strict comfort limits as defined in EN 15251 and Ashrae Standard 55, which suggest a very high level of precision in terms of thermal comfort predictability. The introduction of a certain level of comfort negotiability in adaptive thermal comfort standards might be helpful, to take advantage of the individual range of adaptive possibilities in a specific building. This could support the application of natural ventilation in buildings as well as the satisfaction of occupants.  When predicting adaptive thermal comfort by using building simulation, the results should refer to the weather data set and occupant behaviour the study has been based on, and provide information concerning their likelihood for variability due to different influences.

6. REFERENCES [1] DIN EN 15251:2007-08, Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics, Beuth Verlag, Berlin, 2007. [2] ASHRAE 2004 ANSI/ASHRAE Standard 55R Thermal Environmental Conditions for Human

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Occupancy. Published by American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. [3] de Dear, R & Schiller Brager, G 2001, 'The adaptive model of thermal comfort and energy conservation in the built environment', International Journal of Biometeorology, vol. 45, no. 2, pp. 100-8. [4] Nicol, F & Humphreys, M 2010, 'Derivation of the adaptive equations for thermal comfort in free-running buildings in European standard EN15251', Building and Environment, vol. 45, no. 1, pp. 11-7. [5] Intergovernmental panel on Climate Change IPCC (2007): climate change 2007, synthesis report, summary for policymakers, [6] Founda, D., Papadopoulos, K.H., Petrakis, M., Giannakopoulos, C., Good, P. (2004): Analysis of mean, maximum and minimum temperature in At hens from 1897 to 2001 with emphasis on the las t decade: trends, warm events and cold events, G lobal and planetary change, 44, pp. 27‐38 [7] Pültz, G, Hoffmann, S. (2007): Zur Aussagekraft von Simulationsergebnissen auf Basis der Testreferenzjahre (TRY) über die Häufigkeit sommerlicher Überhitzung, Bauphysik 29, Heft 2, pp 99-109. [8] Meteonorm 6.0, Global Meteorological Database for Engineers, Planners and Education www.meteonorm.com (Accessed 17 Jan. 2010) [9] Relux professional 2007-5 calculation and light design program, http://www.relux.biz/ (Accessed 17 Jan. 2010) [10]DIN EN 12464-1:3-2003: Light and Lighting of work places Part 1: Indoor work places, Beuth Verlag, Berlin [11] Nicol, F., Cunill, E. 2010, ‘Rethinking the comfort limits for free-running buildings in EN 15251’ proceedings of Palenc Conference, 29.9.1.10.2010, Rhodes Island, Greece [12] Baker, N & Standeven, M 1996, 'Thermal comfort for free-running buildings', Energy and Buildings, vol. 23, no. 3, pp. 175-82.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The Influence of Environment on People’s Thermal Comfort in Outdoor Urban Spaces in Hot Dry Climates The example of Damascus, Syria Moohammed WASIM YAHIA1, Erik JOHANSSON1 1

Housing Development & Management, Lund University, Lund, Sweden

ABSTRACT: It is well known that the quality of outdoor urban spaces becomes one of the important items in the urban design process not only for ecological and economical purposes, but also it is important from the social point of view. This study is part of a project in the city of Damascus, Syria which aims to point out the impact of current urban design on microclimate and outdoor thermal comfort in a hot dry climate during summer and winter. The aim of this study is to examine the influence of urban spaces on people’s thermal perception. The aim is also to examine how people experience the aesthetical quality of the urban design in the studied areas (beautifulness, pleasantness). The study also examines the influence of the use of air conditioning devices on people’s thermal perception. This study is based on over 720 structured interviews during summer and winter. Results show clear differences between people’s thermal perception in both summer and winter seasons. Moreover, people's perception of pleasantness and beautifulness is influenced by the weather and climate. On the other hand, no significant impact could be found for the influence of air conditioning devices on people’s outdoor thermal perception. Keywords: hot dry climate, outdoor thermal comfort, outdoor urban spaces, thermal perception.

1. INTRODUCTION In urban settlements, the concentration of people and their activities create intensified demands on the environment. However, this concentration offers opportunities, through microclimatic adaptation, design and actions at an urban scale to minimize the impact on the ecosystem of the region without causing damage. It can then be said that a level of sustainable existence has been reached at which the community can live in symbiotic harmony between design, microclimate, and its environment. On the other hand, it is well known that the quality of outdoor urban spaces becomes one of the important items in the urban design process not only for ecological and economical purposes, but also it is important from the social point of view. Efforts by public agencies and private interest groups to revitalize the central business districts in urban environments have often included large expenditures for outdoor pedestrian spaces. Many such amenity spaces have failed to receive more than light use. This failure has been attributed partly to a general disregard for the physical-comfort needs of the users [1]. The need for thermal comfort is ubiquitous, but it seems often to be forgotten in the designs of outdoor spaces. On the other hand human comfort and energy use of buildings are affected by the local climate conditions within the urban canopy [2] and the microclimate in the urban environment may have a great influence on thermal comfort and the human body.

In warm climates, it is well known that mental and physical performance deteriorates at high temperatures and that heat stress may lead to  heatrelated illness [3]. Moreover, when the body´s adaptive mechanisms to heat stress fail to keep core body temperature close to 37°C, a number of physiological disorders can occur. Among the more common are: Heat exhaustion, heat stroke, heart attack [4]. Thermal comfort is defined as the condition of mind which expresses satisfaction with the thermal environment [5]. Variables of thermal comfort are the air temperature, radiant temperature, relative humidity, air velocity, activity and clothing [6]. The microclimatic factors are affected by the urban surface and at a given point; these factors affect the human activities from ground level up to 2 m height. Recently, the importance of the concept of thermal comfort can be noticed in the latest related scientific researches. Some studies have focused on the influence of urban design and urban geometry on outdoor thermal comfort [7, 8]. Some others have focused on thermal comfort and outdoor activity in urban public places [9]. Others tried to study the thermal perception, adaption and attendance in urban public spaces [10]. This study is part of a project in the city of Damascus, Syria (see Figure 1).which aims to point out the impact of current urban design on microclimate and outdoor thermal comfort in a hot dry climate during summer and winter. This is an area of research which has received little attention in the Middle East from the architectural perspective and it would be the first study of its kind in Damascus.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The main m aim of this study is to examine the influence of outdoor urban spacces on peop ple’s e perception of o thermal com mfort. The aim m is subjective also to exxamine how people p experie ence the therrmal environment in outdoorr urban space es during summ mer and winte er time in Dam mascus as an n example of the hot dry climate. This study is bassed on overr 720 structu ured ate people’s actual therrmal interviewss to evalua perceptio on and to estim mate the aesth hetical qualities of places in n six differentt types of ou utdoor spacess in Damascu us city (stree ets, parks, spaces s between buildings)). This study also takes into account the influence of the use of o air conditio oning devices on people’s thermal t perce eption in outdo oor urban spacces.

Da amascus in 1968 and in add dition he develloped new pla anning regulations for Dama ascus which determined urb ban form for a duration off 20 years 1965-1985. Mic chel Ecocharr’s master p plan and his planning reg gulations werre the essen ntial documents when upd dating the nexxt urban regu ulations in Dam mascus in 199 97.

3. CLIMATE IN DAMASC CUS Damascus ha as hot sunny summers from June to August and mild winters from December to February. Snowfall is com mmon in win nter on the mountains m surrrounding Dam mascus. Sum mmer tempera atures can rea ach in excess of 35°C during the day, butt evenings are e generally co ool. Spring and autumn are e the most com mfortable periods, averaging 22°C during g the day. The average e maximum airr temperature according to the weather stations s for th he period 196 61-1990 in Da amascus durin ng summer tim me is 35.6 °C C and the ave erage minimum temperature during summ mertime is abo out 17.6 °C. On the oth her hand, the e average ma aximum air tem mperature durring winter tim me is about 13.9 °C while th he average minimum air temperature me is about 2.5 5°C, see Figurre 2. durring winter tim

Figure e 1: The location n of Damascus city c in Syria.

2. THE E CITY OF DA AMASCUS The city c of Damascus (Elevation: 620 meters, Latitude: 33.5° N, Lon ngitude: 36.5° E) is located d in south-west of Syrian Arab Republic in the Mid ddle East. Dama ascus (Latitud de: 33.5° N) has a hot dry climate but it is actuallyy located on th he limit of hot dry zone which is normallyy found betwe een latitudes 15° and 35°. Damascus ha as two main pa arts: 1- The old part. Old Damascus has a wealth h of historical sites dating back b to many different periods of the ciity's history. It has a reg gular planning g in general, with w streets oriented o N-S and a E-W. Typ pical style of architecture a in Old Damascu us is simple frrom outside and rich fro om inside with w an inw ward orientatio on to the cou urtyards. Narrrow streets and canyons are the main form of outdo oor urban spa aces in Old Da amascus. 2- Th he modern part. p The app proach to urban design ch hanged radica ally during the e French colo onial period 19 920–1945. Ne ew areas werre built with wide w streets in a grid pattern n and buildings were outwardly e in oriented [11]. The currrent features of architecture modern Damascus were w derived from f the masster de by Frencch architect Michel Ecoch har. plan mad Ecochar presented the new master m plan for

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Figure 2: The average vallues of tempe erature and rela ative humidity in n Damascus cityy for the period 1961-90.

4. MATERIAL LS AND METHODS Field measurements and a questionnaire survey we ere conducted d during su ummer and winter in Da amascus Cityy to describe differentt thermal env vironments as a well as to determine e outdoor the ermal comfort.. However, thiis paper discu usses only the e survey studyy. Since the summer and d winter se easons in Da amascus have the most extrreme weather,, the study wa as only condu ucted during A August and September S 200 09 for the sum mmer, as well as during January and February 2010 for f the winterr time. In both h summer and d winter seassons, a surve ey in outdoor physical env vironment wa as carried o out through structured inte erviews, colle ecting data ab bout thermal sensation, s clo othing and pe eople’s activitiies both in old o and in mo odern Damasccus.

PLEA2011 - 27th International conference e on Passive an nd Low Energy Architecture, Lo ouvain-la-Neuve e, Belgium, 13-1 15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

4.1. Sam mple The sample of this study contained 720 nts of which 360 3 in the winter season and participan 360 in the t summer season. Sixx locations were w selected for case studies and 60 interviews were w conducted in each loccation. The in nterviewees were w between 20 and 65 ye ears of age of which 78% were w males and 22% were fe emales.

que estionnaire took an average of 5 min to complete. Approximately, 60 6 questionna aires were con nducted in ch area. eac SPSS 18 (Statistical Pa ackage for th he Social Sciences Softw ware for Win ndows) was used to ana alyze the ansswers by calcu ulating freque encies and Pearson Chi-Squ uare test.

4.2. Env vironment of the t studied areas a Since outdoor therrmal comfort is of importance dential areas as well as for parks in for resid Damascu us, six locatio ons were se elected for case c studies and were divided d into three kinds of es. The purp pose of dividing those six categorie locations into three ca ategories was to study various physical environments in Damascuss in order to see the differrences betwe een them con ncerning outd door thermal comfort and its relationsship with urban design. The first category - outtdoor spacess in modern Damascus D - contained c thre ee studied are eas: Al Gassa any area whiich is located d in the eastt of Damascu us, see numb ber 2 in Fig. 3, New Dumm mar area whicch is located in the west off Damascus, see number 3 in Fig. 3, and d Barzza area a which is loca ated in north east e of Damascus, see num mber 4 in Fig g. 3. The seccond categoryy - outdoor spaces in Old Damascu us - containe ed only dee ep canyons and narrow sttreets and Al Qaymarieh Q Strreet was seleccted to represe ent Old Dama ascus, see nu umber 6 in Fig g. 3. The third d category - parks p in mode ern Damascu us – contained d two measurrement areas: Al Tigara Park P which is located in the east of Damascus, see number 1 in Fig. 3, and Al Mazzza Park which h is located in n the west off Damascus, see s number 5 in Fig. 3. f study took place betw ween 12:00 and The field 15:00 on both weekdays and weeke ends. At this time t ay, both the air a temperaturre (Ta) and so olar of the da radiation reach their daily d maximum m, and all pla aces e most visitorrs. The field study was only o have the performed d on days without w precip pitation. Answ wers when pre ecipitation occcurred were exxcluded from the analysis. 4.3. Insttruments The questionnaire q was designe ed to assess the people’s thermal perce eption, climaticc and aesthettical overed questions preferencces in Damasscus, and it co about gender and age e, clothing, liviing or working g in f being in the places, time t the city, the reason for spent outtdoors and in the places, th he assessmen nt of the micro oclimate, the aesthetic a qualiities of the pla ace, emotiona al state, and assessing a the attitude to urban outdoor exposure. e This paper p discussses only the results r of therrmal comfort perception, p ae esthetical qua alities of placces, and the influence of the use of air condition ning o people’s the ermal perception. devices on 4.4. Procedure The structured s interview forms were w answered d by people in ndividually und der the supervvision of a group of studen nts belonging to Damascus University. Each

Figure 3: The e six urban spa aces in Damascus for the cas se studies. Read d section 4.2

 

5. RESULTS AND DISCU USSION In each sea ason, a totall of 360 peo ople were inte erviewed in order o to examine people’s thermal perrception, aestthetical qualitties of places s, and the inflluence of the e use of air cconditioning devices on peo ople thermal perception. p   5.1 1. Thermal co omfort perce eption Figure 4 illusstrates the cle ear differences s between peo ople’s answ wers concern ning thermal comfort perrception in bo oth the summ mer and winter seasons (Ch hi-square = 29 94.6, P=.000, df = 8). Figure e 4 shows tha at the people’s thermal perrception in the e summer tim me is between cool and veryy hot, whereas s in winter tim me their therm mal perception n is between very cold and d hot. The majority m of peo ople feel comffortable in the e winter time whereas w they feel hot in the summer tim me. The resultt shows that the distributiion of the ans swers are widely w spread in both sum mmer and win nter seasonss and that this is because of diffferences of people’s therm mal perception ns besides the e complexity of o the outdoor thermal en nvironment con ncerning the e weather cconditions. A similar

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

distribution between the summer and winter seasons has been found in the subtropical climate of Sydney, Australia [12].

                           

Figure 4: Percentage frequencies for people's thermal perception in both summer and winter seasons.

 

5.2. Aesthetical quality of the place Figure 5 shows the percentage frequencies for the aesthetical quality of the places (beautifulness, ugliness). Result shows that the majority of the people, 72% and 82% in summer and winter respectively, experience the same places during the summer and winter seasons as beautiful whereas, only 18% and 13% in summer and winter respectively experience the places as neutral, and 10% and 5% in summer and winter respectively experience the places as ugly (Chi-square = 10.52, P=.005, df = 2). In addition, the results show that the people experience the same places in the winter season more beautiful than in the summer season. The results imply that, people's perception of beauty is influenced by the weather and climate. The result agrees with other studies in different climates [13].

                         

only 19% and 16% in summer and winter respectively experience the place as neutral, and 13% and 6% in summer and winter respectively experience the place as unpleasant (Chi-square = 11.14, P=.004, df = 2). In addition, result shows that the people experience the same places in the winter season more pleasant than in the summer season. The results imply that people's perception of pleasantness is influenced by the weather and climate. The result agrees with other studies in different climates [14].

                         

Figure 6: Percentage frequencies for people's perception of beauty (pleasantness) in both summer and winter seasons.

 

5.3. The influence of air conditioning devices on thermal comfort Since Damascus has a hot dry climate, people usually have air conditioning devices either at home or at work. Figure 7 shows the percentage frequency in summer and winter seasons for people who use the air conditioning devices and for those who do not. The result shows that around 73% of the interviewees use air conditioning devices whereas, 27% of the interviewees do not use them. Thus, air conditioning devices in Damascus city are widely used during summer and winter time either for heating or for cooling purposes. This can be explained by the lack of the comfortable conditions and the need for better thermal adaption between indoor and outdoor environment.

Figure 5: Percentage frequencies for people's perception of beauty in both summer and winter seasons.

Figure 6 illustrates the percentage frequencies for the aesthetical quality of the places (pleasantness, unpleasantness). Result shows that the majority of the people, 68% and 78% in summer and winter respectively, experience the same places during summer and winter seasons as pleasant whereas,

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Figure 7: Percentage frequencies for people who use the air conditioning devices.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 8 shows the influence of the use of air conditioning devices on people's outdoor thermal perception in summer time. The result shows that there is no significant difference between the people who use air conditioning and those who do not concerning outdoor thermal perception (Chi-square = 6.3, P=.390, df = 6).

 

Figure 8: The influence of the air conditioning devices on people's outdoor thermal perception in summer season.

 

Figure 9 reveals the effect of the use of air conditioning devices on people’s thermal perception in winter time. Figure 9 illustrates that there is no significant difference between the people who use air conditioning and the people who do not concerning outdoor thermal perception (Chi-square = 10.5, P=.162, df = 7).

                         

Figure 9: The influence of the air conditioning devices on people's outdoor thermal perception in winter season.

 

Consequently, there is no clear relationship between outdoor thermal perception and the use of air conditioning devices. The reason could be that people adapt quickly to their outdoor conditions in spite of the differences between indoor and outdoor environments. Other studies for indoor environments reported that there is significant difference between the people who use air conditioning at home or in the office and the people who do not concerning thermal comfort perception [15].

6. CONCLUSIONS As regards the thermal comfort in Damascus city, the influence of microclimate on people's thermal perception in the summer season is completely different from the influence in the winter season at the same places. In summer time, the study found that the majority of interviewees felt hot. This can be improved by enhancing the urban design [16] in Damascus city as well as by adding trees or shading devices [17] in order to provide shade for people who pass or linger on these places. In spite of the differences in people's thermal perception at the same places between summer and winter seasons, people experience the places as beautiful and pleasant regardless of the differences in seasons. So the current urban design of the study areas has been recognized by interviewees as beautiful and pleasant. On the other hand, the beautifulness and the pleasantness of the place is affected by the quality of the urban design, In addition, thermal comfort is very well needed for enhancing the quality of the urban spaces especially in a hot dry climate. Therefore, the considerations of outdoor thermal comfort should be taken into account in the urban design process. Regarding the influence of the use of air conditioning devices on people's outdoor thermal perception, no significant result was reported in spite of the big number of the people who use air conditioning devices. However, when people use air conditioning, the microclimate in the summer time will be negatively affected because the exhaust heat from the air conditioning devices will lead to increased air temperatures in outdoor urban spaces. Therefore, encouraging people's desire to spend much more time in outdoor urban spaces will help to reduce the use of air conditioning. On the other hand, the good quality of urban design is needed to attract people to spend time in outdoor environments.

7. FUTURE STUDIES More studies, including both summer and winter seasons will be performed within the framework of the project including statistical analysis of the emotional states, preferable weather conditions, and evaluating the outdoor activities for the people who live in Damascus. In addition, simulation studies will be conducted in order to give examples to enhance the thermal environment in outdoor urban spaces in Damascus city.

 

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

8. REFERENCES [1] W. H. Whyte (1972), Please, just a nice place to sit .N. Y. Times Sunday Mag. 3 Dec. 1972. [2] B. Givoni (1998), Climate considerations in buildings and urban design. New York: Van Nostrand Reinhold. [3] D.A. McIntyre (1980), Indoor climate, Applied Science Publishers Ltd, London. [4] P. A. Bell (red) (2001), Environmental psychology, Fort Worth.Tex: Harcourt College. [5] H. J. Plumley (1977), Design of outdoor urban spaces for thermal comfort. In: Heisler, Gordon M.; Herrington, Lee P (Red). Proceedings of the conference on metropolitan physical environment; Gen. Tech. Rep. NE-25., 152-162. PA: U.S. Upper Darby. [6] ASHRAE (2004), Thermal environmental condition for human occupancy. Atlanta: American Society of Heating. [7] E. Johansson (2006a), Influence of urban geometry on outdoor thermal comfort in a hot dry climate: A study in Fez, Morocco. Building and Environment 41: 1326–1338. [8] E. Johansson (2006b), Uurban design and outdoor thermal comfort in warm climates – studies in Fez and Colombo. PhD Thesis, Housing Development & Management, Lund University, Lund, Sweden. [9] I. Knez and S. Thorsson (2007), Thermal, emotional and perceptual evaluation of a park: Cross-cultural and environmental attitude comparison. Building and Environment, 43 (2008) 1483-1490. [10] T. Ping Lin (2009), Thermal perception, adaption and attendance in a public square in hot and humid regions. Journal of Building and Environment, 44, 2017-2026. [11] K. Al-Kodmany (1999), Residential Visual Privacy: Traditional and Modern Architecture and Urban Design. Journal of Urban Design, 04, 283-312. [12] J. Spagnolo and R. de Dear (2003), A field study of the thermal comfort in outdoor and semioutdoor environments in subtropical Sydney Australia. Building and Environment, 38,721738. [13] I. Knez (2003), Climate: A nested structure in places. The 5th International Conference on Urban Climate (ICUC-5) (pp. 65-67). Poland: University of Lodz. [14] I. Knez and S. Thorsson (2006). Influences of culture and environmental attitude on thermal, emotional and perceptual evaluations of a square. International Journal of Biometeorology, 50, 258-268. [15] J.F. Busch (1992), A tale of two populations: thermal comfort in air- conditioned and naturally ventilated offices in Thailand. Energy and Buildings 18:235-249.

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[16] F. Ali-Toudert and H. Mayer (2007), Effects of asymmetry, galleries, overhanging facades and vegetation on thermal comfort in urban street canyons. Solar Energy, 81, 742-754. [17] J.M. Ochoa and R. Serra (2009), Vegetation influences on the human thermal comfort in outdoor spaces. Retrieved June 10, 2010, from School of Architecture of Barcelona, Dept. Constructions Arquitectòniques I & Dept. Física Aplicada, Web site: http://www-

fa.upc.es/personals/jroset/lyonvege.html          

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Statistical Model Evaluation and Calibrations for Outdoor Comfort Assessment in South Florida. Jean-Martin CALDIERON, Mate THITISAWAT, Kasama POLAKIT, Giancarlo MANGONE College for Design and Social Inquiry, Florida Atlantic University, Fort Lauderdale, Florida, USA. ABSTRACT: In tropical and subtropical areas, people can spend more time outdoors than in other latitudes. Understanding the sensitivity of outdoor comfort is a fundamental element for architects and urban designers working in these specific climates. This study is part of a research project attempting to relate climatic influences and human thermal sensation. The primary objective of this funded research is to study the influence of climatic parameters in outdoor comfort. This paper analyzes the climatic parameters such as temperature, radiation, humidity, and wind speed in four selected public spaces in the downtown area of the city of Fort Lauderdale, Southeast Florida. The climatic data was correlated with thermal sensation surveys of occupants using selected public spaces. This paper presents data from the surveys, evaluates two existing statistical models, and proposes two calibrated statistical models to predict thermal comfort based on the values of mean radiant temperature, wind velocity, relative humidity, and air temperature. The analysis of this data will establish parameters for architects and urban planners to have a more appropriate design for specific outdoor public spaces in the area of Fort Lauderdale. This research project is funded by Architectural Research Centers Consortium (ARCC) and Florida Atlantic University (FAU) Keywords: South Florida tropical climate, outdoor comfort, statistical model calibrations, climate surveys.

1. INTRODUCTION This study is based on survey data compiled in the City of Fort Lauderdale, which is located in a semitropical region. The four sites utilized are open public spaces within an urban fabric. These sites host a combination of variables: natural features vs. man made features, and linear vs. park/plaza space. The study presents data from the survey, evaluates statistical models, and calibrates them using the survey data. Most people living in South Florida do not walk or use outdoor public spaces as much as the inhabitants of other tropical and sub-tropical areas throughout the world. According to the survey, participants spend about 2.6 hours per day outdoors. Private cars transportation is more dominant than public transportation. Some reasons for less outdoor living are the availability of parking areas, the relative low density and the inadequate public transportation. Outdoor comfort plays an important role in the use of outdoor spaces. The millions of visitors that arrive each year to South Florida beaches and other attractions appreciate the climate of the region. However, temperatures can be very high during the summer months. Relatively high temperature together with high humidity is one of the reasons why many Floridians spend relatively little time outdoors. In the case of Fort Lauderdale, as with many other cities in the South and Central area of the state, one of the main problems is high solar radiation due to lack of shading to protect outdoor spaces. More than 70% of the participants in the sites with less natural features would like more shading trees or structures. In South Florida there is a predominant use of several species of palm trees in the cities landscape. Palm trees are considered exotic for the tourists

visiting the state from cold regions; however they do not produce enough shadow to encourage the use of the surrounding areas. Adequate and well-designed outdoor spaces in conjunction with the study of outdoor thermal comfort will help to improve the quality of outdoor public spaces.

2. OUTDOOR THERMAL COMFORT 2.1. Importance of outdoor thermal comfort: The development of design parameters and a more knowledgeable understanding of outdoor thermal comfort can enhance the quality of outdoor spaces. Well-designed outdoor spaces can improve the economy, natural ecology, social well-being, and lifestyles of the local communities. The development of outdoors spaces with optimal thermal comfort have been shown to increase local real estate values, urban pedestrian and cycling levels, and public transportation usage. Successful spaces that attract a large number of people have been found to attract businesses, workers, and residents (1). Therefore, the local communities can become more economically profitable through outdoor space designs that combine different strategies to respond to summer and winter conditions. The consumption of building energy can be reduced by providing shading from solar radiation in the summer and potentially providing a radiant heat source in the winter through the provision of an exterior thermal mass. 2.2. Metric model for Outdoor thermal comfort: A standardized metric model for determining optimal thermal comfort for occupants of outdoor spaces has undergone a development. The model development requires localizations responsive to

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local climates. Psychological adaptation plays an important role in the model development for the outdoor thermal comfort assessment (3). In previous research (4), the psychological adaptation includes effects from: naturalness, expectations, experience (short/long term), time of exposure, perceived control and environmental stimulation, These parameters have a variant percentage of impact, and should be considered in relation to whether these parameters can impact design decisions, and vice versa. The psychological adaptation effects can produce disagreement between model predictions and actual sensation votes. Hence, there are needs for model adjustment to fit the local climatic conditions.

 

People living outdoors falsely assume that the outdoor thermal microclimate cannot be controlled through architectural design or mechanical control, and thus, they perceive a broader range of conditions as ‘acceptable’ in regards to climate (2). Research has shown that quantifiable, microclimatic physical parameters can account for approximately 50% of the variation between subjective and objective comfort evaluation.

 

2.3. PMV model This research focused on modifying the internationally accepted thermal comfort prediction model for building occupants, PMV. Fanger developed this method in the late 1960’s via testing the comfort level of college students in steady airconditioned interior environments within moderate thermal climate zones (2). PMV predicts the mean thermal sensation vote on a standard scale for a large group of people in any given combination of thermal environmental variables, such as activity, and clothing levels. PMV has been shown to be inaccurate in predicting occupant thermal comfort in naturally ventilated buildings, as well as in outdoor spaces (3). Regardless of inadequate predictions of outdoor thermal comfort conditions using the PMV, the results of this research project developed substantive correlations between actual thermal comfort votes and predicted thermal comfort votes, through the development of a thermal prediction model based on PMV. Discrepancies still occurred, which can most likely be attributed to the lack of inclusion of psychological adaptation into the model, although further research into this phenomenon is required. Furthermore, this model cannot be applied at a global scale within varying climate zones, and has not been tested for varying seasons. Utilizing a standard metric system for multiple outdoor sites within a specific thermal climate region provides a basis to compare, quantify, and qualify the thermal qualities, comfort levels, and design characteristics of inherent heterogeneous outdoor environments. As previous research has identified (5), a city’s outdoor spaces cannot be analyzed and evaluated as a whole, but rather evaluated on an individual basis. Therefore each space is unique providing them with different thermal qualities due to the surrounding local environment. This methodology

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has the potential to identify the design parameters, qualities of outdoor space, and individual physiological and psychological parameters that lead to optimal outdoor thermal environments. In this paper, a statistical regression model is proposed. Researchers have been working with climatic data such as radiant temperature, wind velocity, and humidity as parameters for a statistical model. (1) and (6). This research is a pilot study to understand the validity of proposed models.

3. DESCRIPTION OF THE EXPERIMENT METHODOLOGY: 3.1. Selected Public sites: The research is based on interviews with the users of the selected public sites and climatic data collected during the process. The data was recorded in four different public areas located in downtown Fort Lauderdale during 2010 Summer and Fall. The first site is the Broward County Main Library Plaza/Park (Figure 1), this is one of the few spaces downtown where local people congregate. The plaza has a generous grass area surrounded by matured trees, the pavement leading to the library entry occupies less than twenty percent of the total area.

  Figure 1: Aerial view of the Broward County Main Library Plaza/Park

The second site is Riverwalk (Figure 2), a waterfront touristic pedestrian corridor adjacent to the New River. The proximity to the water is an opportunity to create a favourable microclimate. Nowadays, the discontinuity of shading and the abundance of hardscape pavement make this area uncomfortable to be used as a resting place.

 

Figure 2: Aerial view of the Riverwalk

The third site is Las Olas Boulevard (Figure 3), a longitudinal corridor with small commercial, retail, restaurants, and some shading trees. The

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

-Point measurements of the skin and the clothing temperatures of each interviewer. A modified version of the questionnaire is presented bellow.

commercial activities and shadows allow the continuous use of this outdoor space throughout the length of the corridor.  

 

Figure 3 : Aerial view of Las Olas Boulevard

  The last selected site is the University Plaza ( Fig 4). This sector is walled on two sides by University buildings. Due to the proximity of the educational buildings, it is expected to anticipate a significant participation of users within the gathering space. Unfortunately the plaza lacks sufficient shade and appropriate vegetation and it is also exposed to adjacent traffic on both east and west front. A better design will allow this space to be used by the public more frequently. As detailed in this section, the selected sites for the study have unique characteristics that allow for obtaining a diverse data pool.    

  Figure 4: Aerial view of the University Plaza 3.2 Survey interviews methodology: The surveys comprise an interview of almost 100 users at the four selected public spaces. User activities within the selected spaces range from walking, resting, exercising or just passing through. Most of the interviews were realized during the noon and afternoon hours due to higher levels of activities and user volume in the selected public areas. The survey questions revealed information such as: -The user’s characteristics including city of origin gender, age, height, weight and skin colour. -Activity that the user has been involved in the last 15 minutes. -Descriptions of clothing and clothing adaptation (preference to remove or add a clothing item). -Duration of being outdoors. -Daily average of time spent in an air-conditioned space and outdoors. -Sensation votes related to: comfort, humidity, wind, sunlight. -Opinions on the selected urban spaces and the use of public urban spaces.

Figure 5: Modified Survey interview questionnaire.

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From all the data collected in the interviews, this paper only uses the results of the actual sensation vote according to a proposed 9-point thermal sensation scale. The scale is similar to the ASHRAE scale, differing by an additional category to incorporate a very hot thermal sensation. The proposed 9-point thermal sensation scale is compared to the ASHRAE scale in Table 1.

Table 2: Climate data during the surveys interviews in Fort Lauderdale.

Avg WBT © Avg DBT © Avg Globe©

Table 1: 9-point thermal sensation scale compared with ASHRAE scale.

AvgWBGTout © 9-points

ASHRAE

St Dev

Min

Max

23.5

2.2

21

27.2

28.6

1.6

26.7

31.4

32.4

7.0

26.8

46.4

26.1

3.1

22.8

31.2

Value

AvgRH (%)

0.6

0.1

0.4

0.8

4

1.7

0.9

0.3

3.2

56.9

25.4

30.5

84.7

Hot

Hot

3

Airflow (m/s) AvgHea tIndex ©

Warm Slightly warm

Warm Slightly warm

2

4.2 Survey interviews results:

Neutral Slightly cool

Neutral

0

Slightly cool

-1

Cool

Cool

-2

Very hot

1

3.3 Climatic data methodology: Detailed climatic data was measured during each interview using portable mini-weather stations. The data comprises the following measurements: - Amplified Pyrometers to measure the global and diffuse radiation - A QuestTemp 36 portable monitor able to measure: - Mean radiant temperature, - Relative humidity - Wind speed - Dry and wet bulb temperature - Data loggers type CR200X record the data in intervals of 1 second during each interview, and generate averages every 1 minute to match the same recording resolution of QuestTemp 36.

4. RESULTS The collected data in the survey is complex and only some parameters are analyzed in this paper. Further surveys in all the seasons and additional user surveys will provide more complete results than in this pilot study. 4.1 Climate data results: The average values of the most important climatic data collected during the interviews are presented as a reference in Table 2. The data only includes interviews and measurements taken during the day. Early morning and night data is not part of this experiment. In future research, the climatic data will include additional hours and all the seasons of the year.

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From all the data recollected in the surveys, this paper uses only the actual sensation vote (ASV). Table 3 shows the percentage of each value of the thermal sensation scale in relation to the air temperature at the moment of the interview. The original 9-point thermal sensation scale described in Table 1 was reduced to six points because none of those interviewed voted for any of the last three cold thermal sensation options. The average air temperature or dry bulb temperature was 28.56 °C during the interviews and the standard deviation was 2.2 °C. This small deviation is explained by the fact that the data was gathered during the summer and fall seasons when changes of temperature usually are not pronounced in South Florida. Table 3: ASV of those interviewed in relation with the air temperature

(ASV)

Air Temperature © 26<28

28<30

30<32

Cool (%)

5.3

0

0

Comfortable (%)

30.6

14.7

2.7

Warm (%)

4

9.3

1.3

Slightly hot (%)

1.3

4

5.3

Hot (%)

0

4

14.7

Very Hot (%)

0

1.3

1.3

5. MODELLING THERMAL COMFORT: In order to find a correlation between the ASV and the data collected during the interview, two correlation models were developed.

 

5.1 Statistical Model SV1 The first one uses the following variables: MRT= Mean Radiant Temperature V= Wind Velocity RH Relative humidity AirTemp: Dry bulb temperature

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The original formula was developed by a pilot study in Greece by Nikolopoulou, (7), and its formula is as follow: SV1 = 0.061*(AirTemp) + 0.091*(MRT-AirTemp) 0.324*(v) + 0.003*(RH*100) - 1.455 SV1 is the sensation vote of the original formula. Figure 6 present a scattered diagram between the ASV and the original model SV1. Root Mean Square Error (RMSE) is used to evaluate the predictive power of the model. A lower value of the RMSE indicates a small degree of disagreement between model predictions and the ASV. The data has a RMSE of SV1 model is 1.1603.

Looking at the statistical influence of each parameter, the air temperature is the most important factor in the model. There is a stronger correlation between the standard vote of the model and the Actual sensation vote (ASV) of the public in model SV2 in comparison with model SV1. 5.3 Statistical Model SV3 A third model is proposed for this study. The original values for this model was developed by Marques and Peinado (6) The formula components are the same as the models SV1 and SV2, the equation is as follow: SV3 = -3.557 + 0.0632 (AirTemp) + 0.0677(MRT) + 0.0105(RH)- 0.304*(v) SV = sensation vote or thermal sensation perception MRT = mean radiant temperature RH = relative humidity v = wind velocity The RMSE of this original equation is 1.3999. Figure 3 shows a scattered diagram of the ASV and the model proposed SV3. Even when this model is working in a lineal pattern as expected and there is a strong correlation between the public opinion or ASV, the model SV3 has a RMSE much higher than in the statistical model SV2. The scattered table of the model is presented in Figure 8. .

Figure 6: Scattered table of actual sensation vote (ASV) in relation with the sensation vote in the calibrated model (SV1)

5.2 Statistical Model SV2 A second proposal is SV2, a calibrated model of SV1 expressed as follow: SV2 = 0.2336*(AirTemp) + 0.1886*(MRTAirTemp) + 0.0252*(v) + 0.0478*(RH*100) - 9.2268 It was found that the formula above yielded a root mean square error (RMSE) of 0.6967, has a very satisfactory performance. (Fig 7)

 

Figure 8: Scattered table of actual sensation vote (ASV) in relation with the sensation vote in the original model (SV3)

5.4 Statistical Model SV4 The final model proposed in this paper is SV4. This model uses the same formula as SV3 and the calibration realized yields:

 

SV4=9.2268+0.0450*AirTemp+0.1886*MRT+4.7846* RH+0.0252*v

Figure 7: Scattered table of actual sensation vote (ASV) in relation with the sensation vote in the calibrated model (SV2)

The prediction using SV4 produces a RMSE of 0.6967 This model works much better than the model SV3, Figure 9 represents the same type of scattered

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diagram presented for the other models. As in the SV2 calibrated model the ASV has a good correlation. As a conclusion the calibrated models can be used in future research after incorporating some changes. Interestingly, their root mean square errors between the prediction and the ASV are identical in the calibrated models SV3 and SV4. This is due to the fact that they are both linear regression models with similar climatic parameters in the equations.

7.

ACKNOWLEDGEMENTS

Architectural Research Centers Consortium (ARCC) and Florida Atlantic University (FAU) have financially supported this research project.

8. REFERENCES [1] Marialena Nikolopoulou, Nick Bakera and Koen Steemers, (November 2010) Thermal Comfort in Outdoor Urban Spaces : Understanding the Human Parameter , Solar Energy Volume 84, Issue 11, Pages 1879-1974 (November 2010) [2] J. Van Hoff, (2008) Forty years of Fanger’s model of thermal comfort: comfort for all? Indoor AirVolume 18, Issue 3. [3] Marialena Nikolopoulou, Koen Steemers (2003) Thermal comfort and psychological adaptation as guide for designing urban spaces Energy and Buildings 35 95–101 [4] Spagnolo, Jennifer; de Dear, Richard (2003) A field study of thermal comfort in outdoor and semi – outdoor environments in subtropical Sydney, Australia. Building and environment, Vol. 38, Issue 5, p.721-738.

Figure 9: Scattered table of actual sensation vote (ASV) in relation with the sensation vote in the original model (SV4)

6. CONCLUSIONS This paper is a pilot study of a research project investigating the complex parameters influencing thermal comfort in outdoor spaces. The complexity of the relationship between the different climatic and psychological parameters requires future research and a more complete data pool to include all the seasons of the year. The main problem is not only the thermoregulatory system of the human body responding to climatic conditions, but also the psychological adaptation parameters. Two previously proposed statistical models are evaluated. Their structures are comparable to each other due to the use of linear regression technique. Prediction results of the models exhibits trends that follow the ASV. One of the models SV3 was proposed for a subtropical area. However, the level of agreement between predictions using the models, and the ASV is not adequate. Subsequently, the two models were calibrated to develop two new models that yield considerable improvement. In future research the calibration can be improved and other parameters could be included in new model formulas.

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[5] H. Mayer and P. Höppe (1987) Thermal comfort of man in different urban environment Theoretical and applied climatology, Volume 38, Number 1, 43-49, [6] Leonardo Marques Monteiro, Marcia Peinado Alucci (2009) Thermal Comfort Index for the Assessment of Outdoors Urban Spaces in Subtropical Climates. The seventh International Conference on Urban Climate 29 June - 3 July 2009, Yokohama, Japan [7] Marialena Nikolopoulou, Spyros Lykoudis and Maria Kikira (2003) Thermal comfort in outdoors spaces, field of studies in Greece, 5th International Conference on Urban Climate, IAUC-WMO, September Lodz, Poland.

             

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Adaptive Principles for Thermal Comfort in Dwellings From Comfort Temperatures to Avoiding Discomfort Noortje ALDERS1, Stanley KURVERS1, Eric VAN DEN HAM 1

Delft University of Technology, the Netherlands

ABSTRACT: Many theories on thermal comfort exist and there are many ways to deliver this in an energy efficient way. Both aspects are often studied in a static way and most of these studies only regard one of the aspects, seldom investigating what influence the way of delivering thermal comfort has on the actual perceived thermal comfort. This paper analyses the knowledge of the different disciplines and integrates it to get a holistic image of comfort and its delivery systems as well as opportunities in energy saving and enhanced thermal comfort. Furthermore, it aims to understand the dynamics of weather, thermal comfort and occupancy in dwellings, finding the opportunities for quality improvement and energy saving. The paper explains the framework considered for further development of new concepts for comfort delivery and an analytical method for optimizing dynamic building characteristics. This research is part of a PhD project at the Delft University of Technology. Keywords: thermal comfort, dynamic analysis, energy, adaptive dwelling

1. INTRODUCTION As civilization is advancing, the demand for thermal comfort is increasing, as is the case for all kinds of comfort. With regard to the design of thermal comfort amenities for homes, new concepts for dwellings should be developed to meet the development in increase of comfort demand. Specifically the need for flexibility and adaptivity of the dwelling and its comfort system are eminent in the following shifts of focus in the Netherlands [1]: -

More varying use of the home and individual spaces. Individual differences in (thermal) comfort experience get more pronounced and important to account for. Increasing differences in health sensitivity. Individualisation increases the need for prevention of internal nuisance. Increasing need for adaptability to future climate chance.

Technically, it is possible to provide any thermal environment requested and so is the provision of diversity in thermal environment. However, various studies point out that it is not only the physical thermal environment that determines thermal comfort [2-4] and that over-conditioning leads to more health problems and general complaints [5]. Furthermore, the greater the difference between outdoor climate and requested indoor climate, the more energy is required to supply and maintain this indoor climate. Therefore, it is essential to define the range of environmental conditions under which people feel comfortable, optimizing circumstances for health and productivity while limiting energy consumption. Besides the physiological parameters, other conditions should be considered as well, like the possibilities for influencing the environment and the context of thermal perception as this greatly enhances the acceptance of the thermal environment and thus the range of accepted temperatures.

In the office environment where the setpoint temperature often is to be controlled centrally it is still useful to determine average comfort temperatures for the target group. In this way it is likely that, statistically, as many people as possible are satisfied, optimizing their productivity. However, in dwellings people are considered in charge of their own environment and they should be able to control their setpoint temperature individually. The dwelling and the comfort system should facilitate the occupant to create their own environment. Furthermore, various studies point out that thermal comfort is not related to only one fixed temperature or temperature range [68]. It is also not possible to calculate thermal comfort with a formula of only physical variables, like the ASHRAE definition already implicates: "thermal comfort is a state of satisfaction on the thermal environment". The main conclusions are that thermal comfort, like the demand for other types of comfort, is very personal and relative to time, place and situation. These aspects shift the question from an actual comfort temperature to a range of temperatures that should be avoided to ensure absence of discomfort likely to occur due to the thermal environment and the variability of this range as well as the constraints for other aspects that influence the perception of thermal comfort. The main question becomes; What is the range and diversity of thermal comfort demand that can be expected and what are the most appropriate ways of delivering this thermal comfort in an energy efficient way without compromising the feeling of homeliness? Because there are so many factors that determine whether there is a demand for influencing the thermal environment for comfort and at which level, answering this question requires a multi-disciplinary approach. Not only the physiological and quantitative approach should be considered, but also sociological and cultural as well as the technical approach are necessary to be able to meet these various demands

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in an energy efficient way. Furthermore this paper aims to clarify the non-quantifiable qualities that homes should have in order to propagate the wellbeing of its occupants. After all, a home is a place to feel at home. Above all it should offer protection and comfort in a wider sense.

2. COMFORT AS A SUBJECTIVE DYNAMIC CONCEPT

AND

When talking about comfort, the people that design and produce the systems to deliver it, quantify the concept of comfort by introducing standard calculation models, calculating the thermal neutral temperature using physical parameters as input. It takes the temperature of thermal neutrality as exact thermal comfort temperature, standardizing all people in one model. This approach is often applied as it is a clear method for assessing quality and predicting cost. These calculations by comfort models, like the heat balance model of Fanger [9], appear more scientific, because exact and finite. However, the requirements calculated from them are only reliably obtained by mechanical means, on which they are based. In this way, air conditioning created its own market and necessity because natural means cannot deliver these exact values [3]. However, quantifying this based on merely physical values leaves out important factors in perceived comfort. Without doubt, there is a thermal niche [10], defined by the range between a critical lower temperature and a critical upper temperature, outside which people would not survive for long. Inside this thermal niche there is also a general neutral zone, defined by a lower comfort limit and an upper comfort limit, within which there will be minimum effort to keep the heat balance between the body and the environment. However, the thermal neutral temperature isn’t necessarily the same as the thermal comfort temperature. When the thermoregulatory system is balanced there are many other factors that determine one’s comfort. If you are bothered by one aspect you are more likely to be uncomfortable by other things; so within the thermal niche, negative factors decrease tolerance for the thermal environment and cause to narrow the bandwidth in which people feel comfortable. Therefore, great care should be taken to how the comfort is delivered and the quality of the system, avoiding discomfort that can frustrate the feeling of comfort. Not only should the physical properties of thermal comfort be assessed, but also the nonquantifiable assets. Furthermore it deserves attention that people enjoy the action of alleviating discomfort rather than being comfortable all the time [11, 12]. The level of comfort is neither a static nor a global phenomenon. Neither is the occupancy or the activity in the house. The dynamics of stimuli experienced by the occupant, both thermal and non-thermal, bring about a perception of the thermal environment by the occupant. Depending on the thermal state moments before, but also the more distant past experience are important, as well as the state and personality of the occupant and the context of the thermal environment.

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The adaptive opportunities are of great influence as well, regardless of the actual physical change they cause. The perception of one and the same set of thermal conditions can be different almost any time. Therefore it should not be globally defined by standards and rigid numbers. In the end this can lead to expectations of homogenous thermal environments all over the world, which does not only have a negative effect on health and comfort, but can lead to excessive energy consumption, trying to fit all the indoor environments to that one rigid standard [2, 13]. Furthermore, people prefer diversity in their environment over a homogenous one, both in time as in locality [11, 14, 15]. In this way they are able to experience the thermal environment and enjoy it, which stimulates the feeling of homeliness. To determine a range of the comfort demand that could occur, this research uses existing comfort models. However, the way it deals with these models is different, because it regards the models as probabilistic information rather than deterministic as well as taking into account the dynamics of comfort perception and taking into account more aspects than just the physical aspects. In general, from the thermal comfort models developed from the 1930s, the adaptive comfort models (for example, ASHRAE 55 [16] or EN15251 [17]) best describe the situation in homes [18]. Because all of these standards were developed for offices, the following aspects need to be taken into account. The approach is evident in the following; this approach can be used as an opportunity to better provide the comfort demand and to achieve energy savings: Thermal sensitivity of people varies with the context and expectation. This means that per individual, thermal sensation and comfort experience may vary, at constant thermal environmental factors. These can be both physiological (body weight, vasomotion) and mental (expectation, habituation). In addition, people’s thermal sensitivity may vary from person to person. Older people for instance are more sensitive to discomfort and hypothermia or overheating due to reduced thermal perception and reduced physiological adaptation [19, 20]. This means there is no fixed optimal temperature at which least people experience discomfort in a given situation. In this study, the comfort temperatures are not regarded as a precision. Because in the home, there is a small population which can control their own environment, these bandwidths are regarded as a probability distribution of increasing improbability of occurrence. This statistical dispersion of comfort temperatures will be greater in homes than in offices, because the sample is larger, with more individual differences, and the setpoint temperature can consequently differ significantly per household. In homes the adaptive capabilities are typically greater than in offices by the possibility of customized clothing, activity, location and opening of windows and doors. This leads to greater acceptance of the

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

climatic conditions and thus a broadening of the bandwidth of accepted temperatures. Within the broad temperature limits that need to be secured, the controllability of the temperature and the thermal environment are almost as important as the temperature range itself. This means that the setpoint temperature is not a single value (like stated above) but a temperature range which can be easily adapted by the user within the given bandwidth and possibly even outside this bandwidth. Adaptive Comfort Models focus more on a steady state situation, with one comfort temperature per day. However, the activities change throughout the day and so is the assessment of the comfort. This is partly due to the expectation that the temperature on the day varies by the natural course of the outdoor temperature and the response of the dwelling and its comfort system. Different comfort bandwidths will be regarded for different functions because of the difference in activity levels, clothing insulation, expectations and adaptive opportunities. These algorithms are used as an example. Actual data for the Dutch situation is no available and the questions and data are mainly based on studies in offices, where the activities and overall circumstances are different than in dwellings. However, these algorithms are used as an example, to clarify the method. More data can later be implemented. The bandwidths for the living area are adopted from the SCATS project [7]. The bandwidths used for bedrooms and bathrooms are adopted from a Belgian research by Leen Peeters [21]. Figure 1 depicts boundaries for heating and (passively) cooling indoor spaces. The bandwidths are defined by the following boundaries; for heating, there is a minimum, given by the temperature above which most people feel comfortable and a predefined system boundary, above which more people will feel uncomfortable and therefore above which it would be inefficient to heat. Likewise, for cooling there is a minimum and a maximum of cooling for energy efficiency and thermal comfort. Even the width of the bandwidth can vary from person to person and even situation, according to the thermal sensitivity of people. The following constraints must be bared in mind too: For children the indoor climate is controlled by the parents. It is assumed that in general they have larger physiological adaptation, but because they have fewer behavioural adaptive capabilities it will comfort area within the same limits. Adaptive comfort models can not directly be translated to use for actively cooled residences. This project will attempt to provide comfort without active cooling (use of (additive) energy for the generation of cold). Combining the detailed weather data with detailed occupancy profiles can create detailed comfort demand profiles that inform about patterns in the required indoor environment. In this research, different occupancy patterns are compiled, for the

most common household compositions and for comparison, some less expected patterns. 

Figure 1: Example of adaptive bandwidths for space temperatures for living areas and bedrooms as a function of the prevailing outdoor temperature (Running mean outdoor temperature).

3. DYNAMICS OF WEATHER To make the system able to seize upon every conceivable situation, an analysis of variance should be made, in order to know what kind of combinations of factors are most likely to occur and which situations are so rare that they could be omitted. A combination of frequency distribution, weekly occupancy profiles, simulation and load duration curves will be used in this study. The following weather variables are most influential on the indoor climate and will be compiled into frequency tables for the past 30 years in weather station de Bilt (the Netherlands): -

Ambient temperatures Solar irradiation (total on surface) (during day) Daily and hourly temperature fluctuations (Wind speed and direction)

The coincidence of some weather variables can pose extra constraints on the indoor climate and comfort. These will be compiled in cross frequency distributions, to see where highest demand will occur, for example: -

High ambient temperature + high solar radiation Low ambient temperature + high wind speed especially coming from North

4. DESIGN OF ADAPTIVE DWELLINGS AND COMFORT SYSTEMS Most buildings are designed for average weather circumstances and the dynamic behaviour of the

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building is seldom regarded. However, if you look at the dynamic behaviour of weather and the occupant, the dynamic thermal behaviour of a building is crucial. Because of the diversity in perception and demand, the system should be flexible to be sufficient in all conceivable scenarios and adaptive to the changing user needs and be energy efficient in just delivering these fluctuations of need. A dwelling and its comfort system can be designed to benefit from the prevailing dynamics of weather and occupancy, adjusting various settings, like insolation, insulation and ventilation, according to these dynamic demands and outdoor climate.

 

T outdoor within comfort bandwidth

Figure 2: Frequency table depicting differences between outdoor temperature and demanded temperature bandwidth for a living room in July in ‘de Bilt’ (the Netherlands), with occupancy hours and bandwidth of comfort temperatures. With the frequency tables per hour of the day (possibly compared to average daily course per month) together with occupancy profiles per room, an estimate can be made of variance of occurring demand and possible solutions. In figure 2 an example is given with the comfort bandwidth (2K above and below the average comfort temperature) and an example of occupancy hours. The dynamic thermal behaviour of a building can be outlined by a number of specific properties. The properties of delay and damping the indoor temperature fluctuation relative to the behaviour of the outdoor temperature are most important. These influences can be calculated in an analytical way by an estimation model. In this model the settings of the building (e.g. high or low insulation / shading on or off) can be calculated, per hour or per day, depending on the techniques used. The following parameters are considered dynamic: Instantaneous (independent variables) T�∗ � required indoor temperature [°C] T� � outdoor temperature [°C] q��� � solar incidence [W/m2] W��� � internal heat gain [W]

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COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

Instantaneous (control variable)  ����� � characteristic heat loss coefficient by ventilation [W/K] Per day or season (control variables) ������ = characteristic heat loss coefficient by transmission [W/K] (e.g. thermal shutters) � � ratio of admitted solar incidence through a transparent surface [W/K] � � accessible thermal mass [J/K]

 

Instantaneous (Dependent variable) W���� � heating or cooling power applied [W]

 

The independent variables are q��� , T� , and W��� . The dependent variables are Ti and Winst; Ti should remain in the Tc range (thermal comfort bandwidth) and Winst should be minimized. All other variables can be considered control variables, that are adjustable within certain ranges and with a certain rate, depending on the variable and techniques used. With these equations, the optimal settings for these variables can be calculated per hour or per day and possibly per season. These settings could then be depicted in similar frequency distributions as for the weather and thus determine the required physical behaviour of adaptive comfort systems for dwellings and their components. Numerous Climate Responsive Building Elements and installation techniques are already available or being developed which can fulfil these required physical behaviours and this research can give an impulse for others to be developed.

5. ADAPTIVE COOLING

HEATING

AND

PASSIVE

The now remaining energy demand for comfort (Wheat) should be delivered in an energy efficient and flexible way with a high degree of user control. In the summer season the aim is to avoid all active cooling by preventively flushing excess heat to ensure that the upper limit of the comfort temperature is not achieved (not even during absence). However, these passive measures are slow and cannot prevent that the temperature still rises at the time of activation of the measures. Because these measures are far less energy demanding than active cooling, they can be used as a preventive measure, when the temperature has not yet reached the upper limit and also during absence. The Dutch climate is suitable to provide for the required indoor climate in this way for the major part of the year. If the dynamic behaviour of the home has been determined, the threshold temperature for preventive passive cooling can be specified as well. In winter, if passive measures are not sufficient, heating is required. However, the patterns of presence can be unpredictable and the general and average schedules programmed in the usual clock thermostat for heating can cause the heating system to be operational even if people are absent, or the need to adjust the thermostat when present unexpectedly. This almost always leads to unnecessary and unwanted energy use because the

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

thermostat is not turned off automatically at times of unscheduled absence and people will take a margin leaving the heating on, in case they would be home unexpectedly. Furthermore, normally the thermostat only controls the sensor in the living room, thus heating the entire dwelling at the same time. To account for this lack of predictability of the comfort demand, it is useful to operate the heating on momentary presence per room or zone. With an eye on comfort and energy saving, the heating preferably only switches on at presence. This means that the heat up time must be limited. There are various measures to ensure fast heating up: for instance enough capacity, low thermal mass or a certain lower limit for the temperature at absence. The behaviour of the total system, the passive and active components of the house, defines these parameters. During this heat-up-time the basic temperature should be reached and subsequently the temperature can be adjusted according to the preferences of the user. Basically, the heating can be turned off immediately when leaving the room. The temperature will not quickly drop in a well-insulated house. The building elements should be flexible and responsive to the dynamic circumstances of weather and user demand (operable shutters, blinds, windows etc). The ranges of flexibility of the different elements, like range of U-value for the windows or range of ventilation capacity, can be determined by the use of the estimation model mentioned in paragraph 4. Provided the temperature behaviour is predictable and there is a possibility to correct the temperature within the given comfort area, the temperature may fluctuate at a speed of 2 K/h maximally. This fluctuation is hardly noticed and has no negative impact on comfort [19]. With simulations, the outcomes will be validated.

6. FURTHER CONSIDERATIONS; ACCEPTANCE

USER

Like all (new) technologies, in order for people to accept them and to propagate the desired behaviour to make the system efficient, a number of factors need to be considered first before designing and being able to pronounce in the end on energy saving or quality of the building. The two most important factors are Perceived Usefulness and Ease of Use, like described in the Technology Acceptance Model (TAM) used in sociology and information management [22]: -

-

 

Perceived Usefulness: The degree to which a person believes that using a particular system would enhance his or her daily life. Ease of Use: The degree to which a person believes that using a particular system would be free of effort.

 

To ensure a high degree of Perceived usefulness and ease of use, the following aspects need to be considered

Motivation: The occupant needs to know why an amenity is there. For heating or cooling this is evident, but for ventilation this is not always the case, let alone if the ventilation system is combined with the heating or cooling system. In the case of energy saving it is even more difficult. Saving costs in energy is usually not so obvious. The energy bill is only presented in the end of the year and mostly people don’t know exactly how and where energy is saved.

 

Transparency in operation: The occupant needs to experience in one way or another, why the system is doing what it’s doing. If there are too many things going on of which the occupant doesn’t know what the purpose is, this can lead to stress, discomfort and counteractions to alleviate this discomfort. However, the counteractions can be irrational if the occupant doesn’t understand the systems action, which can lead to more energy consumption, system failure and even more discomfort. This is especially important for systems that operate things that concern our health, like ventilation and to a lesser degree heating and cooling. Flexibility: The settings should be flexible to be sufficient in all conceivable scenarios. Control: It is important that occupants have as much control as is practically possible. Various studies point out that when occupants can control their (thermal) environment, the tolerance for inconveniences increases. These controls should be, like the system itself, perceivably useful [12, 23, 24].

 

In their report on controls for end users, Leaman and Bordass discuss the requirements for good controls [23]. The main aspects are listed here:

 

Intuitive: To increase the ease of use for most occupants, the controls need to be intuitive as there is no possibility for training, other than a written guide. Feedback of control: If the control is used, there should be an immediate feedback that shows the system status. This could be a tangible feedback like a click, or an indicator light indicating the system had “read” the control input. Feedback of effect: The intended effect of the control should be noticeable. This could be the heating of the radiators that shows the furnace is on.

7. DISCUSSIONS AND CONCLUSIONS Contrary to what the thermal comfort legislation and standards claim, there is no need for precise comfort temperature prediction or measuring in dwellings. Regarding the diverse and dynamic character, together with the adaptive possibilities in a dwelling, make it feasible to assess the thermal comfort quality of a dwelling by its amenities, flexibility and control possibilities. Furthermore, to be able to design a flexible dwelling and comfort system, a method is proposed to analyse the dynamics of both the outdoor climate and the occupancy and comfort

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

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preferences, on which future comfort systems for dwellings can be based. The method can also provide more insight, besides simulations used for legislation purposes, to analyse the response of the building to the outside world (climate) and the possibilities of occupant’s interaction with the system and adjustment of the system to their needs. In that way a risk analyses can be made as to which extreme situations can be tolerated as rarely occurring and which situations need to be avoided and at which cost to prevent unnecessary excessive energy consumption. The remaining work for the PhD will be the development of concepts for comfort systems that can provide the required flexibility and comfort quality in an energy efficient way. The concrete results of the PhD will be guidelines for designing a flexible and adaptive dwelling with an integrated comfort system.

11.

12.

13. 14. 15. 16.

8. REFERENCES 1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

606

BouwhulpGroep, Duurzaam Bouwen, Werken en Wonen Na 2015 - WP 0, in Duurzaam Bouwen, Werken en Wonen Na 2015. 2007, Bouwhulp Groep: Eindhoven. p. 52. Chappells, H. and E. Shove, The environment and the home. Draft paper for the Environment and Human Behaviour Seminar, 2003. Healy, S., Air-conditioning and the "homogenization" of people and built environments. Building Research & Information, 2008. 36(4): p. 312 - 322. Haldi, F. and D. Robinson, On the behaviour and adaptation of office occupants. Building and Environment, 2010. 45(11): p. 24402457. Mendell, M.J., Q. Lei-Gomez, A.G. Mirer, O. Seppänen, and G. Brunner, Risk factors in heating, ventilating, and air-conditioning systems for occupant symptoms in US office buildings: The US EPA BASE study. Indoor Air, 2008. 18(4): p. 301-316. Cole, R.J., J. Robinson, Z. Brown, and M. O'Shea, Re-contextualizing the notion of comfort. Building Research & Information, 2008. 36(4): p. 323 - 336. McCartney, K.J. and J. Fergus Nicol, Developing an adaptive control algorithm for Europe. Energy and Buildings, 2002. 34(6): p. 623-635. Raja, I.A., J.F. Nicol, K.J. McCartney, and M.A. Humphreys, Thermal comfort: use of controls in naturally ventilated buildings. Energy and Buildings, 2001. 33(3): p. 235244. Fanger, P.O., Thermal comfort; analysis and applications in environmental engineering. 1970, Copenhagen: Danish Technical Press. 244 blz. Tracy, C.R. and K.A. Christian, Ecological relations among space, time and thermal niche axes. Ecology, 1986. 67(3): p. 609615.

COMFORT AND OCCUPANCY (INSIDE AND OUTSIDE)

17.

18. 19.

20.

21.

22.

23. 24.

de Dear, R., The theory of thermal comfort in naturally ventilated indoor environments "The pleasure principle". International Journal of Ventilation, 2009. 8(3): p. 243250. Brager, G.S., G. Paliaga, and R. de Dear, Operable Windows, Personal Control and Occupant Comfort. 2004, eScholarship Repository. Hitchings, R., Studying thermal comfort in context. Building Research & Information, 2009. 37(1): p. 89 - 94. Steemers, K. and M.A. Steane, Environmental Diversity in Architecture. 2004. Heschong, L., Thermal Delight in Architecture. 1979. American Society of Heating, R.a.A.-C.E., Inc. (ASHRAE), Thermal environmental conditions for human occupancy, in 55, ASHRAE, Editor. 2004, ASHRAE. Cen, Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics. 2007. Ubbelohde, M.S., G.M. Loisos, and R. McBride, Comfort Reports. 2003, California Energy Commission. Schellen, L., W.D. van Marken Lichtenbelt, M.G.L.C. Loomans, J. Toftum, and M.H. de Wit, Differences between young adults and elderly in thermal comfort, productivity, and thermal physiology in response to a moderate temperature drift and a steadystate condition. Indoor Air, 2010. 20(4): p. 273-283. Kingma, B., A. Frijns, W. Saris, A. van Steenhoven, and W. van Marken Lichtenbelt, Thermoregulation during mild temperature changes: The effect of age. In preparation. Peeters, L., R.d. Dear, J. Hensen, and W. D'Haeseleer, Thermal comfort in residential buildings: Comfort values and scales for building energy simulation. Applied Energy, 2009. 86(5): p. 772-780. Davis, F.D., Perceived usefulness, perceived ease of use, and user acceptance of information technology. MIS Quarterly: Management Information Systems, 1989. 13(3): p. 319-339. Bordass, B. and A. Leaman, Controls For End Users. 2007, BCIA. Haldi, F. and D. Robinson, On the unification of thermal perception and adaptive actions. Building and Environment.

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Investigation of space-heating strategies in very low-energy houses using dynamic simulations Case of decentralized wood stoves approaches Laurent GEORGES1,2, Catherine MASSART1 1

2

Architecture et Climat, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium Department of Energy and Process Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway

ABSTRACT: By definition, passive or very-low energy houses are characterized by low energy needs. From an economical point of view, it is important to minimize the investment for the space-heating system because low consumptions make difficult to amortize this investment. Space-heating using a wood stove is a good trade-off between a low investment and good environmental performances. Nevertheless, wood stoves ask for long production cycles and need to operate close to their nominal power in order to reach their best performances. Unfortunately, these requirements are not easily fulfilled in the context of passive houses as stoves are in general oversized for these applications. Furthermore, compared to a conventional heating, a single stove is expected to ensure the thermal comfort within the entire envelope. In this context, the present paper investigates the performances of this kind of space-heating sources in terms of energy consumption as well as thermal comfort. This is done using dynamic simulations on one single-family detached house geometry. Nevertheless, different architectonic properties are considered highlighting the major effect of the internal thermal inertia. Finally, differences between constant and intermittent heating are also analyzed. Keywords: low-energy houses, passive houses, space-heating, stove, dynamic simulations

1. INTRODUCTION Passive houses are characterized by very low space-heating (SH) needs and relatively small heating powers. This power is indeed limited to 10 W/m² which corresponds to the maximum power that an air-heating system can provide using standard hygienic ventilation rates. Air-heating using the ventilation network should significantly reduce the distribution system, typically by avoiding the installation of a conventional hot-water loop equipped with radiators [1]. This simplification reduces the investment allocated to the SH system, a saving that is preferably injected to improve the superinsulation of the envelope. In theory, the SH simplification is sufficiently important so that the passive house standard should be an economical optimum [2]. For the time being, overinvestment to ensure the envelope performances is most often higher than savings on the SH system and savings on operating energy so that the theoretical optimum is not always reached at the passive house level. In practice, this overinvestment is mainly affected by the tripleglazing as well as by the controlled mechanical ventilation. Nevertheless, in the context of very low energy houses, the environmental and economical equilibrium for SH systems is not straightforward. The consumption is, by definition, low so that it is more critical to pay off large investments. Unfortunately, larger investments typically correspond to the most efficient systems or to systems based on renewable energies. On the contrary, SH systems characterized by low investments, favourable from an economical point of view, often have poor environmental performances. The best example is the direct electric heating which lowers the investment drastically but has a high primary

energy consumption (as long as electricity is generated by classical power plants using fossil fuels). An interesting alternative is to resort to a stove using wood logs or pellets [3]. The investment is indeed relatively low and the environmental performances are ensured as wood is a renewable energy (as long as forests are exploited in a sustainable way and transport limited). The exact environmental footprint of wood heating is behind the scope of the paper but it is commonly admitted that it has a better impact on the CO2 emission than classical fossil fuels (i.e. natural gas or oil). The objective of the present contribution aims to analyse the performance of wood stoves in the context of the SH of very low energy houses.

2. CONSTRAINTS FOR THE SPACEHEATING USING WOOD STOVE IN PASSIVE HOUSES 2.1. Characteristics of the passive house spaceheating The required power to heat a passive house is relatively low. In design weather condition, this power is approximately ~2kW for a detached single-family dwelling in the Belgian temperate climate. In parallel, an accumulation domestic hot water (DHW) production asks for a power typically ranging from 2 to 4kW. Furthermore, an additional power is required if the building is heated intermittently in order to perform the boost phase after a set-back period. Nevertheless, the instantaneous heat demand of the house is in general lower than 2kW. The nominal powers of the main existing systems are well higher than these 2kW. This is true for condensing gas or wood boilers with 6-8kW,

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standard heat pumps with 6-8kW as well as wood stoves. Even with the power modulation of these systems (e.g. up to 10-30% of the nominal power for gas boilers), the heat output is larger than the heat demand of the building. Exceptions exist, for example, the electric heating and the so-called “compact” airwater heat pumps. When existing, this oversizing leads to on-off cycling of the production device unless a buffer tank is introduced between the production and emission. In passive houses, the internal and solar gains have a large contribution to counterbalance the losses of the envelope. In fact, their power can be equal or even higher than the envelope losses so that the heat demand of the building to the production system is well intermittent. Again, this shortens the production cycles.

Figure 1: Elevation of the two-storey’s house following the North, South, East and West façades, respectively.

The ground floor has a large living-room facing the South that is coupled with the kitchen. The second floor consists of four bedrooms with an adjacent bathroom. The building model considers 10 distinct thermal zones. All these zones are maintained at a set-point temperature of 20°C except a laundry room located on the first floor. During the set-back period, the set-point temperature is lowered to 16°C.

2.2. Requirements of the space-heating using wood stoves Wood stoves have two mains characteristics that have to be related to the aforementioned constraints. First, wood stoves have to operate on long production cycles in order to minimize their emission of pollutants and reach their best performances. The order of magnitude is a minimum of 30min for a pellets stove and 1h for a log stove. Second, best efficiencies are reached close to the nominal power. From a production point of view, the best scenario for a wood stove is long production cycles at nominal power while the passive house characteristics ask for small intermittent heating powers. 2.3. Detailed objective of the contribution The well-focused objective of the present investigation is to evaluate the performances of a stove operating on a long production cycle close to nominal power in a passive or very low-energy single-family house. The major risk is to obtain an overheating leading to a significant increase of the consumption (1) or a major discomfort (2). The first phenomenon will be translated by a loss of regulation efficiency while the second by the maximal temperature reached during the annual heating period.

3. METHODOLOGY The thermal behaviour of a detached single-family house is analyzed using dynamic simulations, here using TRNSYS. The present section aims to develop the numerical set-up and methodology.

Figure 2: Sketch of the ground and second floor, respectively (the South direction points upwards).

Distinct architectonic properties are considered. A first distinction is made between the inner thermal inertia using five different wall compositions, reported on Table 1. Let us mention that thermal inertia is here considered in the context of the SH and not for overheating issues during hot summer periods (although it is well known that inner thermal inertia is beneficial in this respect). Table 1: Wall composition of the five levels of thermal inertia.

3.1. Detached single-family house The geometry of the detached single-family is kept constant throughout the test cases. This is a twostorey’s building with a net heating surface of 150m². The envelope has a protected volume of 420m³, a 360m² transmission surface and 35m² of windows. The plans of the house are reported on Figs. 1 and 2.

Inertia Massive heavy (I1) Massive light (I2)

HVAC - EQUIPMENT AND REGULATION (COMPLEMENTARY TO DESIGN)

Lagging

Slab

CalciumConcrete Wood fiber silicate blocks (high-inertia)

Floor Concrete

Cellular concrete blocks

Mineral wool

Concrete (low-inertia)

Wooden

Wooden heavy (I3)

Wooden framework

Wood fiber

Concrete (high-inertia)

Concrete

Wooden light (I4)

Wooden framework

Mineral wool

Concrete (low-inertia)

Wooden

Wooden framework + concrete partition walls

Mineral wool

Concrete (high-inertia)

Concrete

Mixed (I5)

610

External walls

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

In order to discriminate the thermal behaviour specific to the passive standard, three different levels of insulation for the envelope are investigated. The first is representative of the passive standard. The second corresponds to the application of the current minimal requirements of the EPBD regional policy [4]. In between, an intermediate level is considered that is here termed low-energy. The passive and low-energy test cases are equipped with a controlled mechanical ventilation coupled to a heat recovery unit (its efficiency is here set to 0.85). Ventilation rates are established using the regional policy. Air tightness is also adapted according to the insulation level. The U-values of walls are summarized in Table 2. Table 2: U-values as a function of the insulation level under investigation (in unit [W/m².K]). Element

Passive

Low-Energy

EPBD

Glazing

0.6 (triple)

1.1 (double low-e)

1.1 (double low-e)

Window

0.8

1.6

1.6

Door

0.8

1.8

1.8

External walls

0.11

0.2

0.4

Ground

0.15

0.2

1.0

Ceilings

0.11

0.175

0.32

Table 3: Global thermal properties of the 15 variants using the EN ISO 13790 norm [5] (Total losses in [W/K], internal inertia in [MJ/K] and characteristic time scale in [h]). Insulation level

Inertia level

Passive (90 W/K)

LowEPBD Energy (354 W/K) (145 W/K)

I1 (69.8 MJ/K)

214.2 h

133.2 h

54.8 h

I2 (20.9 MJ/K)

64.4 h

40.0 h

16.47 h

I3 (32.7 MJ/K)

100.5 h

62.5 h

25.7 h

I4 (10.9 MJ/K)

33.5 h

20.8 h

8.56 h

I5 (43.5 MJ/K)

133.4 h

82.9 h

34.13 h

Zone

1

2

3

4

5

6

7

8

9

10

Pdmax Passive

0.6 0.2 0.1 0.2 0.2 0.2 0.1 0.2 0.3 0.1

Pdmax Low-E

1.0 0.4 0.3 0.3 0.3 0.3 0.2 0.3 0.4 0.1

Pdmax EPBD

2.9 0.7 0.7 0.9 0.7 0.6 0.4 0.7 1.0 1.5

Pmax solar

2.8 0.3 0.2 0.6 0.5 0.9 0.2 0.6 0.6 0.1

Pmax internal

0.7

Emax solar

16

Emax internal

3.9 0.0 0.2 0.2 0.8 0.9 0.1 0.9 1.4 0.1

0

0.1 0.2 0.1 0.1 0.1 0.1 0.2 0.1

1.4 1.8 2.8 2.8 4.7 1.1 3.2 3.3 0.5

3.2. Numerical set-up

Combining the five levels of inertia to the three levels of insulation gives fifteen variants. Some global thermal properties of these test cases are evaluated using the EN ISO 13790 [5] and reported in Table 3 (i.e. the inner thermal inertia as well as the characteristic time scale).

Characteristic time scale

Table 4: Maximum transmitted power (Pmax) in [kW] as well as maximal transmitted energy in one day (Emax) in [kWh] for the solar and internal gains during the heating season. Comparison with the maximal losses (Pdmax) in [kW] at design weather conditions (i.e. Text = -10°C). Critical zones are highlighted in grey.

By means of the weather conditions, these values enable to evaluate the theoretical valorisation rate of the solar and inner gains. Typical weather conditions using the METEONORM database are taken for the city of Uccle located in the centre of Belgium. In order to compare the solar and internal gains to the SH contribution, some of their properties are reported here below, see Table 4. The mean power of the internal gains is 2.2 W/m² which is very close to the value recommended in the PHPP (i.e. 2.1 W/m²).

Different types of space-heating (SH) are considered, here termed H1, H2 and H3:  The first one is the so-called ideal heating (H1) where the set-point temperature is maintained in each zone using a pure convective heat source that can modulate perfectly.  The second (H2) introduces the imperfections of the minimum cycle length and the lack of power modulation. A heat source is indeed place in each zone that is activated when the room temperature goes below the set-point temperature. Its power is maintained at the nominal value during a minimal cycle length. Furthermore, the ratio between convected and radiated power has also been changed between test cases. This configuration can be seen has a stove without modulation placed in each room.  The third configuration (H3) considers a single stove placed in the living-room (facing the South). Again, when the living-room temperature goes below the set-point value, the stove power is kept constant at its nominal value during a minimal cycle length. This approach can only ensure the thermal comfort for the passive house insulation level (at least theoretically). Internal doors are assumed to be closed during all the simulations. This assumption increases the temperature non-homogeneity between thermal zones, highlighting the worst situation possible. In order to capture properly the different thermal behaviors, the simulation time step is set to 7.5min. The simulation length is one year. The 5 distinct minimal cycle lengths investigated here are 7.5, 15, 30, 45 and 60 minutes. Installed nominal powers depend on the heating mode. In constant heating, the nominal power for each stove (H2) is equal to maximal total losses in each zone in design weather conditions, see Table 4. In the case of a single stove (i.e. H3), its nominal power is the sum of all the zone losses. In intermittent mode, the set-point temperature is changed depending the hour of the day and the day of the week following a realistic time schedule. In this case, the nominal power of the emitters is proportionally increased to have globally an extra 6kW during the boost phase (whatever the level of inertia considered).

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For test cases H2 and H3, the ratio between the convected and radiated power is fixed to 100% (pure convective source), 50% (mixed source) and 0% (pure radiative source). In the present work, stratification effects on comfort are not considered.

4. RESULTS All the test cases represent a total of 720 simulations. For the sake of clarity, only major configurations are commented here below. In order to decompose the physical phenomena, complexity is introduced in an incremental way.

The comfort is analysed using the maximal temperature encountered during the heating period. The overheating is then defined as the difference between the maximal and set-point temperatures. For the passive house level, Fig. 5, one clearly sees that this temperature strongly varies with the level of inertia. On the contrary, the type and length of heat emission has a minor influence. This can be explained as follows. As reported on Table 4, the leading heating process is the solar gains. Their maximal power is 3 to 4 times higher than the nominal power of stoves so that solar gains are the major variable to be controlled to ensure the thermal comfort.

4.1. Decentralized stoves in each thermal zone (H2) with a constant set-point temperature

Figure 3: Annual heating demand with a constant set-point temperature of the passive house H2 case as a function of the minimal cycle length for a pure convective (solid line) and pure radiative heating (dashed line). Ideal heating H1 is pictured at the origin of the X-axis as, in theory, no cycle length is imposed.

Figure 5: Maximal overheating with a constant set-point temperature in the passive house H2 test case as a function of the minimal cycle length for a pure convective heating (solid line) and radiative heating (dashed line). Ideal heating H1 is pictured at the origin of the X-axis.

The case of a constant set-point temperature is first analysed with a stove in each zone (H2). As depicted in Fig. 3, the higher the inertia, the lower the SH need. The difference is rather clear for the passive house but becomes negligible considering the EPBD test case, see Fig. 4.

Figure 6: Maximal overheating with a constant set-point temperature in the EPBD H2 test case as a function of the minimal cycle length for a pure convective heating (solid line) and radiative heating (dashed line). Ideal heating H1 is pictured at the origin of the X-axis.

Figure 4: Annual heating demand with a constant set-point temperature of the EPBD H2 case as a function of the minimal cycle length for a pure convective (solid line) and radiative heating (dashed line). Ideal heating H1 is pictured at the origin of the X-axis.

The curve shapes in function of the cycle length are similar between the different insulation levels. The influence of the convection/radiation ratio of the heat source has a noticeable influence on short cycle lengths (radiative sources have higher consumptions).

612

The situation is very different for the EPDB insulation level, as depicted on Fig. 6. Solar gains still have a strong influence. Indeed, overheating using perfect heating still ranges from 0.5 to 5.0°C depending on the level on inertia. A high level of inertia remains thus important. Nevertheless, the complementary heat emitted by the system has here a power comparable to the solar gains (see Table 4) so that the emitter can significantly worsen the discomfort. For example, overheating can be as high as 11°C using a pure convective heating during 1h. The nature of the source is here very important. Using a pure radiative source, the overheating remains almost unchanged with the production cycle length.

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4.2. Decentralized stoves in each thermal zone (H2) with an intermittent heating

4.3. Decentralized stove in one thermal zone (H3) with a constant set-point temperature

The present configuration considers an intermittent heating. The overall nominal heating power of the passive house is here increased by a factor 3.6 in order to perform the boost-phase (i.e. from 2.3 to 8.3kW). For a given cycle length, the energy delivered to the house is thus 3.6 times higher. As a consequence, consumptions reported on Fig. 7 are higher than in Fig. 3 for a same imposed cycle length.

The situation is here very different. A single stove is placed in the living-room and is switched on when the temperature goes below the set-point value. The temperature is thus enforced in a single place. In other rooms, it is expected that the ventilation, equipped with an efficient heat exchanger, will homogenize the temperature. In our case, the set-point temperature is never reached in these free-floating rooms. As a consequence, the heat consumption is lower than the reference net heat demand, by definition computed using a perfect heating (in each zone). This is well illustrated in the Fig. 9.

Figure 7: Annual heating demand in intermittent heating of the passive house H2 case as a function of the minimal cycle length for a pure convective (solid line) and pure radiative heating (dashed line). Ideal heating H1 is pictured at the origin of the X-axis.

Comparing the perfect heating in Figs. 3 and 7, the net heat demand is reduced for each level of inertia. Nevertheless, the higher the inertia, the lower the reduction induced by the intermittent heating, so that the difference in net heat demand between levels of inertia is significantly reduced. On the contrary, for long heating cycles, the consumption difference between inertia levels is rather important (i.e. diverging curves).

Figure 9: Annual heating demand with a constant set-point temperature of the passive house H3 as a function of the minimal cycle length for a pure convective (solid line) and pure radiative heating (dashed line). Ideal heating H1 is pictured at the origin of the X-axis.

(a)

Maximal overheating

Figure 8: Maximal overheating in the intermittent heating in the passive house H2 case as a function of the minimal cycle length for a pure convective (solid line) and radiative heating (dashed line). Ideal heating H1 is pictured at the origin of the X-axis.

In terms of comfort, comparing perfect heating in Figs. 5 and 8 shows, as expected, that the maximal temperature is almost unchanged using the intermittent mode. In intermittent mode, overheating is still dominated by solar gains. Nonetheless, for longer cycles, the delivered power is so high that the performances are worsened by the SH system. In this case, working with radiative sources is beneficial.

(b)

Maximal temperature default

Figure 10: Maximal overheating (a) and temperature default (b) with a constant set-point temperature in the passive house H3 as a function of the minimal cycle length for a pure convective (solid line) and radiative heating (dashed line).

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Comfort is analysed using the maximal temperature during the heating period and the minimal temperature encountered below the set-point temperature (here termed maximal temperature default, Figs 10). The first one takes always place in the living-room while the second corresponds to a bedroom facing the North with a relatively important external surface. The higher the inertia, the lower the overheating and lower the temperature default in the neighbouring rooms. As all the heating power in concentrated in a single place and is comparable to the solar gains amplitude, the nature of the emitters has a strong influence on the overheating. A pure radiative emitter limits this influence (i.e. a maximal temperature constant with the cycle length). On the contrary, a pure convective source gives an overheating as large as 7-9°C, which is not acceptable. Less obvious is the strong influence of inertia on the minimal temperature, in other words, on the homogeneity within the house. The smoothing effect of inertia lowers the extremum of temperature. 4.4. Decentralized stove in one thermal zone with an intermittent heating This test case represents the most realistic configuration where a single oversized stove of 8.3kW is placed in the living-room. This is indeed a representative power for the smallest stoves available. This oversized power is concentrated in a single room (with closed doors) so that the thermal comfort is highly critical, see Fig.11(a). Only a radiative source in a zone with high internal inertia can maintain an acceptable temperature with long production cycles.

Quite surprisingly, the stove power increase between Fig. 10(b) and 11(b) do not manage to reduce the temperature default in the cold bedrooms. The maximal temperature default is indeed almost unchanged between these two test cases.

5. CONCLUSIONS The present contribution aimed to investigate the thermal behaviour of wood stove-like heat sources operating close to their optimal conditions in passive and low-energy houses. In terms of efficiency, Fig. 3 translates the performances of the stoves for a setpoint temperature enforced in each zone. In terms of comfort when working with a single stove, simulations showed the importance of thermal inertia to avoid overheating but also to increase the thermal homogeneity within the passive house envelope. Furthermore, the source must be as radiative as possible to prevent overheating. At the present stage of the study, the objective is to have a proper insight into the physics and detect the dominant phenomena and parameters. It gives qualitative guidelines for the proper integration of wood stoves within very low-energy houses, dedicated to architects but also to the manufacturers. In this way, it takes part to the general effort to develop more efficient and extremely low emission wood stoves. The final objective of the research will be to develop simple quantitative models for the correct integration of wood stoves during the design phase of a very low-energy house. Results could then be generalised to other space-heating systems asking for long production cycles and/or presenting large power oversizing.

6. REFERENCES

(a)

(b)

Maximal overheating

[1] Feist, W. et al., Re-inventing air heating : convenient and comfortable within the frame of the Passive House concept. Energy and Buildings 37 (2005), 1186-1203. [2] Schnieders, J, Hermelink, A., CEPHEUS results : measurements and occupants satisfactory provide evidence of Passive House being an option for sustainable building. Energy Policy 34 (2006), 151-171. [3] Georges, L. et al., Technical and economic analysis of systems for passive and low-energy single-family dwellings: application to the market of th the Walloon region (in French). 9 Passive House symposium, Brussels, Belgium, 2010. [4] Walloon Government, Arrêté du 17 avril 2007 du gouvernement wallon déterminant la méthode de calcul et les exigences, les agréments et les sanctions applicables en matière de performance énergétique et de climat intérieur des bâtiments. [5] EN ISO 13790, Thermal performance of buildings: calculation of energy use for space heating. Brussels, Belgium, 2004.

Maximal temperature default

Figure 11: Maximal overheating (a) and temperature default (b) with an intermittent heating in the passive house H3 test case as a function of the minimal cycle length for a pure convective heating (solid line) and radiative heating (dashed line).

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ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBN th xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Hybrid ventilation as an energy efficient solution for low energy residential buildings Peter FOLDBJERG1, Thorbjørn Færing ASMUSSEN1 and Karsten DUER1 1

VELUX A/S, Daylight Energy and Indoor Climate, Ådalsvej 99, 2970 Hørsholm, Denmark

ABSTRACT: The energy performance of two hybrid residential ventilation systems have been investigated and compared to an all mechanical system. The hybrid systems were a manual control based on fixed dates, and an automatic control which chooses the energy optimal mode on an hourly basis. Three different climates were investigated (Brussels, Berlin and Paris). Results from the thermal simulations show that the energy demand of the hybrid systems is less than the all mechanical system. The reduction with the manual control is in the range of 0 – 2.4 kWh/m², while the intelligent control has a larger potential in the range of 4.0 – 4.9 kWh/m². Natural ventilation is more energy efficient than mechanical ventilation for 45% - 48% of the year. Achieving the potential of the intelligent control requires a control system and automatically openable windows. Presently, no such control systems for residential buildings is widely available at a low cost. As the legislation on energy demands is being tightened, automatic hybrid ventilation control becomes increasingly attractive. A 4 kWh/m² reduction for a Danish 2015 building would correspond to a saving of 11% of the maximum primary energy demand. Keywords: Hybrid ventilation, natural ventilation, residential buildings, energy efficient ventilation.

1. INTRODUCTION

2. METHOD

As the energy demand of residential buildings is reduced due to continued tightening of building codes, the electricity demand for operating the house will represent an increasing part of the total demand. Pumps, fans and other equipment will represent an increasing part of the energy use for residential buildings. The European Union has 20% energy savings by 2020 as a target [1], and member states are obliged to draw up national plans increasing the number of nearly zero-energy buildings [2].

The energy performance of residential buildings with hybrid ventilation systems is compared to fully mechanical ventilated buildings. The demand for heating and fan operation is determined for three scenarios shown in Table 1.

Mechanical ventilation systems with heat recovery provide good energy performance in the heating season. But the mechanical ventilation systems for residential buildings are often designed to be in operation all year, which include the summer period. Even though systems can often bypass the heat exchanger during summer, an electricity demand for fan operation remains. If natural ventilation is used instead during the summer period, the electricity demand for fan operation is eliminated. The potential energy savings from hybrid ventilation systems are increasingly important when the energy demand of buildings is reduced. A previous study showed that the performance of the control system is the main factor, and that automatic control performs better than manual control systems in intermediate and warm climates [3]. The present study investigates the performance of manual and automatic control of hybrid ventilation with regards to energy performance in northern European climates.

Table 1. Short description of the three scenarios simulated.

All mechanical Hybrid with manual control

Hybrid with automatic control

Mechanical ventilation with heat recovery all year. Change from mechanical to natural ventilation at a specific date, where the optimal date is determined for each location, based on minimizing the energy demand Sensor-based control switches between mechanical and natural ventilation based on outdoor conditions, which hour-by-hour chooses the most energy efficient mode of operation

The analyses have been performed for three locations in: Brussels (Belgium), Berlin (Germany), and Paris (France). The used software was the dynamic simulation tool IES VE version 6.02 [5]. 2.1. House topology A 1½-storey house with an 8x12 m footprint is used at all locations. The house is defined in [4]. See Figure 1 for a visual representation.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The manual control algorithm is purely based on fixed dates for turning on or off the operation of the systems. The used dates are found empirically based on preliminary simulations of each location. The following dates were used: • Start natural ventilation: April 1st • End natural ventilation: November 15th The automatic control algorithm is based on the energy demand for the two ventilation methods. The principle is show in Figure 2.

Hybrid Ventilation Control Algorithm Figure 1. Visual representation of the house used in the study.

The total floor area is 163 m², and the window area corresponds to 20% of the floor area, i.e. 23 m² façade window and 4 m² roof window. The windows have a declared U-value of 1.4 W/m²K in vertical position, a g-value of 0.60 and a visual transmittance of 0.77. The floor has a U-value of 0.2 W/m²K, walls have a U-value of 0.3 W/m²K, and the roof has a Uvalue of 0.2 W/m²K. 2.2. System setup A heating system was assigned, with set point at 21°C. The internal loads consist of two persons occupying the building all year and equipment of 3.5 W/m². There is no cooling system installed but the windows are used to vent the building when the outdoor temperature is above 22°C with a maximum opening area of 25%. Half of the windows are used for venting. A constant air change rate of 0.5 ACH is assumed for both the mechanical and the natural ventilation system, to allow comparison between the two ventilation modes. The actual ventilation rate in the case of natural ventilation will depend on the driving forces (wind speed, direction and temperature difference between inside and outside) The mechanical ventilation system is an efficient system with low energy consumption and good heat exchanger performance. The fan power consumption is 1.37 W/(l/s), equal to 82 W at an air change rate of 0.5 ACH. The efficiency of the heat exchanger is 88%. 2.3. The Control Strategies of the hybrid system The purpose of the hybrid ventilation control is to benefit from the advantages of the two ventilation solutions: The heat recovery of the mechanical and the free ventilation of natural ventilation. During cold periods the mechanical ventilation system will have the best energy performance due to the heat exchanger. During warm periods the natural ventilation will perform better as it uses no extra energy for fans (and there is no need for heat recovery).

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Tout > Tsetpoint or Tin > 25°C Yes

No

Use Natural ventilation

Use Mechanical ventilation

Figure 2: Principle of the automatic control algorithm.

Where Tout is the outdoor air temperature [°C], and Tin is the indoor operative temperature [°C]. Tsetpoint is the setpoint temperature for changing between natural and mechanical ventilation mode [°C]. The setpoint is determined based on the most energy efficient mode of operation, where the demand for heating and fan operation is included. When the outdoor temperature is below the setpoint temperature, natural ventilation will cause a higher heat loss than mechanical ventilation with heat recovery. The outdoor temperature is considered a practical indicator of “season”, and more accurate than a calendar-date based indicator, as the weather on a specific date varies from year to year. The setpoint temperature depends on the energy performance of the house, as it will be lower for a high performance house. The optimal setpoint temperature was determined as the first step of the present study. 2.4. Operation costs The costs for running the systems include costs for heating and electricity for fan operation. A mechanical ventilation system needs maintenance in order to function correctly. The ducts and diffusers need cleaning and filters have to be changed on regular basis. The number of filter changes is assumed to be proportional to the number of hours the system is in operation. This is included in the total running costs; cleaning and service of the

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The energy cost is different for each location depending on taxes and energy sources. Statistical data about the energy prices has been found via energy.eu [6]. Electricity is converted to primary energy with a conversion factor of 2.5. The cost of a unit of primary energy is assumed to be the same for electricity and heating. See Table 2 for the price of natural gas and filters in each country. Table 2. Energy and filter costs.

Energy costs (natural gas)

Filter costs

[€/kWh]

[€/pcs]

Berlin

0.08

42

Brussels

0.07

33

Paris

0.06

30

3.2. System feasibility Figure 4 shows the part of year when natural ventilation is used in the two hybrid controls strategies. In the manual control strategy, natural ventilation is used more than in the automatic control strategy. This includes hours during nighttime when mechanical ventilation would have been more energy efficient. The automatic control only uses natural ventilation when it is more energy efficient than mechanical ventilation.

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

systems is not included. It is assumed that filters are changed four times per year for a constantly running ventilation system, i.e. 4 filters per 8760 hours of operation.

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The price for a filter change is based on the price in Denmark. It is assumed that the correlation between energy costs and filter costs is constant.

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3. RESULTS

Figure 4. Part of year when natural ventilation is used.

3.1. Setpoint temperature



The optimal setpoint temperature for the automatic control was determined for the design reference year by determining the primary energy demand for a series of setpoint temperature candidates. Figure 3 shows the primary energy demand, which is determined for Copenhagen only, as the result depends on the thermal properties of the house and is independent of the location. The optimal setpoint temperature is identified as 11°C.

Primary energy demand [kWh/m²]



50

With the automatic control, natural ventilation is the most efficient mode of ventilation for 45% (Berlin), 46% (Brussels) and 48% (Paris). 3.3. Energy demands For each location and case the energy demand as primary energy is calculated. The electricity is converted into primary energy with a factor of 2.5. The annual primary energy demand per square meter is shown in Figure 5. The figure also shows the savings potential in kWh/m² when using hybrid systems compared to the fully mechanical solution.



The saving potentials are in the range of 0 – 2.4 kWh/m² for the manual control, and in the range of 4.0 – 4.9 kWh/m² for the automatic control.

49

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48

47

46

45 8

10

11

12

14

16

18

20

Outdoor temperature [ C]

Figure 3. Primary energy demand for heating and fan operation depending on outdoor temperature.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

  

    

  

4. DISCUSSION



With the automatic control, natural ventilation is more energy efficient than mechanical ventilation with heat recovery for 45% - 48% of the year, highest for the warmest location (Paris).

   







Figure 5. Annual primary energy demand in kWh/m².

The maximum primary energy demand for the 2010 Danish Building regulations for a 150 m² house is 64 kWh/m² which is expected to be reduced to 37 kWh/m² by 2015. A reduction of 4 kWh/m² would correspond to 6% in the current regulations, and 11% by 2015. 3.4. Operation costs



The costs are calculated based on the energy demands and the filter costs, see Figure 6. The filter costs are calculated based on the number of operation hours. In all cases the heating costs are the biggest expense. The filter costs are higher than the electricity costs.   

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



Figure 6. Annual system operation costs.

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The saving potentials are in the range of 0.5 – 0.7 €/m² for the manual control, and in the range of 0.7 – 1.0 €/m² for the automatic control.

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Hybrid ventilation decreases the total primary energy demand at all locations. The decrease is largest with the automatic control (4.0 – 4.9 kWh/m²) but is also present for the manual control (0 – 2.4 kWh/m²). The slightly warmer climate in Paris presents greater potential for savings than Brussels and Berlin. The reduction of operation costs with the manual control (0.5 – 0.7 €/m²) are close to the automatic control (0.7 – 1.0); the operation costs of the two hybrid controls are lower than for a system with mechanical ventilation all year. The manual control is dependent on choosing the optimal dates for changing from mechanical to natural operation. Weather conditions can vary from year to year, so these dates would not be the same from year to year in a physical implementation. The automatic control will adjust to actual climate conditions, and therefore the performance of the automatic system will be relatively better in a physical implementation than in this study. A dedicated control device that chooses the optimal mode of operation for a residential building is presently not available on the mass market. As electrically operated windows are becoming increasingly widespread, the additional price of a control device that switched between natural and mechanical ventilation will be low. As the legislation on energy demands is being tightened, the investment to reduce the demand by 1 kWh/m² will increase. This will make automatic hybrid ventilation control increasingly attractive. A reduction of 4 kWh/m² for a Danish 2015 building would correspond to a saving of 11% of the maximum primary energy demand.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

5. REFERENCES [1] European Commission. 20 20 by 2020: Europe's Climate Change Opportunity, (COM (2008) 30 final). Commission of the European Communities, Brussels (2008). [2] European Commission. DIRECTIVE 2010/31/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 19 May 2010 on the energy performance of buildings (recast). Commission of the European Communities, Brussels (2010). [3] Foldbjerg, P., Asmussen, T.F. and Duer, K. Hybrid ventilation as a cost-effective ventilation solution for low energy residential buildings. Proceedings of Clima2010 (2010). ISBN: 978975-6907-14-6. [4] Kragh J., Laustsen J. B. and Svendsen, S. Proposal for Energy Rating System of windows in EU. DTU-R201. Technical University of Denmark (2008). [5] IES VE 6.1.0. http://www.iesve.com. Integrated Environmental Solutions Limited, Glasgow, UK (2010). [6] Europe’s Energy Portal (last accessed November 2010). http://energy.eu.

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Design Strategies for Community-Scale Renewable Energy Solutions Lisa D. IULO1, Rohan R. HAKSAR2 and Seth BLUMSACK3 1

Department of Architecture, The Pennsylvania State University, University Park, PA, USA Department of Architecture, The Pennsylvania State University, University Park, PA, USA 3 Department of Energy and Mineral Engineering, The Pennsylvania State University, University Park, PA, USA 2

ABSTRACT: The strategies, policies, and financial models for community-scale renewable energy production and distribution exist and in some cases are immediately achievable. A gap in information seems to be that the spatial and regulatory implications for implementation of community-scale renewable energy are widely unknown to the architects and developers responsible for planning these projects. This problem is two-fold: 1) even if a community is interested in pursuing a renewable energy project, very little information exists on how to achieve the goals; more detrimental is the fact that 2) most people are unaware of the possibilities for locally owned / used, community-based renewable energy production and distribution, or fearful of exploring this option due to misconceptions. This focused study explores precedents for renewable energy production and distribution in architecture and community design, specifically projects that demonstrate efficient renewable energy strategies at the community scale, in the interest of demonstrating proven methods for implementation. Keywords: community-scale renewable energy

1. INTRODUCTION The energy demands associated with buildings are a major contribution to greenhouse gases and other harmful emissions. The technologies and strategies for achieving goals associated with transitioning to a low-environmental-impact renewable energy future exist, and although they will continue to improve with time, the precedents are sufficiently advanced at the present to allow for major penetrations of renewable energy into mainstream design and societal infrastructures [1]. Communityscale generation and distribution of renewable energy - specifically solar, wind, and non-fossil fuel based combined heat and power plants (CHP) - are clean, efficient, and reliable approaches to generating energy. In addition to reduced environmental impact, potential benefits of community-based small-scale distributed generation include increased security/reliability as well as economic opportunities (in many states and throughout the EU this includes the opportunity to sell surplus power to the utility-owned power grid) and the potential for improved services and economic savings for customers [2]. Most important to our work, community-scale energy projects allow communities to make energy decisions consistent with mutually shared preferences and goals. Existing literature, including Karl Mallon (ed.), Renewable Energy Policy and Politics: A handbook for decision-making (London: Earthscan, 2006), Greg Pahl, The Citizen-Powered Energy Handbook: Community Solutions to a Global Crisis (Vermont: Chelsea Green Publishing Company, 2007) and Barry G. Rabe, Statehouse and Greenhouse: The Emerging Politics of American Climate Change Policy (Washington, D.C.: Brookings Institution Press, 2004), and several articles (including reports by the Pew Center on Global

Climate Change), provides background for community-scale renewable energy projects. Urban Infrastructure In Transition: Networks, Buildings, Plans edited by Simon Guy et al (London: Earthscan, 2001) considers ‘sustainable’ infrastructure, including green building design, and particularly the reactions of various stakeholders to case study projects. One book, Photovoltaics in the Urban Environment: Lessons Learnt from Large-Scale Projects (London: Earthscan,2009), presents successfully implemented strategies for community-scale renewable energy projects related to solar. Although collectively this literature presents some examples and speaks to specific technologies and policies for realizing community-scale renewable energy solutions, it largely does not comprehensively present spatial information of value to the professional responsible for the design of a community-scale project that will include production and distribution of renewable energy. This study, currently in its beginning stages, explores strategies relevant to the integrative design of groups of buildings and renewable energy systems. Specifically this research considers planning and implementation strategies for renewable energy production and distribution in existing and new mixed-use and residential communities. The focus of the study is on models that directly benefit a community. Projects where energy assets are located within the community and serve that community, rather than a development model where renewable energy assets are built on community property by a private energy company and connect directly to regional utility transmission networks. The development model is already well studied and documented; we feel that there is opportunity for wider applicability of the communityscale model.

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2. BACKGROUND Twenty (20) case-study projects of existing and planned sustainable communities that implement renewable energy strategies in Europe and the United States were analyzed. These case studies were used to identify commonalities and trends with the intention of eventually informing spatial guidelines for community scale renewable energy solutions. The case studies were analyzed across a broad range of parameters including renewable energy solutions applied, cost, incentives and ownership models. The projects studied are located in Europe and the United States, most between the latitudes of 19°N and 48°N, with the exception of the proposed Low2No project in Helsinki, Finland (60°N). The average area of the communities studied was 710 hectares (approximately 2.75 square miles) and include multiple buildings, typically mixed-use, with 50 or more residential units. Some smaller communities were studied, typically representing rural or suburban communities. Some of the larger communities, for example the Kronsberg district of Hannover, Germany, tended to account for future urban expansion. The motivation for the implementation of renewable energy in the communities studied were generally in response to rising fuel costs and/or the need for a local financial stimuli, sustainable initiatives taken by local citizens or government (especially in the EU). A few projects in the US were the initiative of an individual project developer. See Table 1. Table 1: The graph below shows initiators of communityscale renewable energy projects most often identified in the case study projects. Local “Sustainable Initiative,” including policy, was the most significant motivating factor (fifth column from left); “Citizen movement” (often in opposition to other energy projects, most notably nuclear), “High Fuel Costs” and “Financial Stimuli” (first three columns from left) were other frequently cited initiators. A couple of projects (2 each) employed renewable energy in response to “Outdated Energy Systems” and the necessity for improved “Energy Security”.

Table 2: The bar graph at the top right of this page indicates types of renewable energy and other sustainable design strategies most commonly employed in the projects including (from left) wind, solar, biomass, geothermal, “Green Design” measures including reducing energy demand, and strategies for the use / reuse of resources.

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Table 2: Types of Renewables employed




The most favoured form of renewable energy used in the projects studied was solar followed by biomass gasification. Many of the projects also implement additional strategies including groundsource geothermal and other sustainable planning strategies. Table 2 indicates types of renewable energy and other sustainable design strategies most commonly included in the projects studied. It goes without saying that reducing energy demand through passive low-energy design and energy-efficiency measures must come before considering renewable energy production. Overall project costs varied greatly depending on the scale of the project, the renewable technologies used, and how they were implemented; also a few revitalization projects were considered. Our best attempt was made to determine overall cost (construction + renewable energy) standardized by size. The average cost of the communities studied was approximately US$132,49 million / square mile. Incentives available are a major factor in the formation and success of a project. As indicated in Table 3 below, incentives range from government-based grants, Renewable Energy Credits and tax credits to donations from companies. As expected, a distinct trend is that government funding is more prevalent in the European case studies than in the United States.

Table 3: Incentives for the implementation of communityscale renewable energy projects include government-based grants, Renewable Energy Credits, other tax credits and donations.




Utility-owned renewable energy projects and Co-ops are the favoured ownership / management models used by most sustainable communities. This is mainly because a firm owns or manages the renewable energy systems reducing up-front costs for the customers while providing reliability and

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

quality. The customer-generated model allows the community to control the energy resources and the potential for profit. Management in this case is obviously more complex and requires additional study. In some of the case-study projects individual customers could invest in a share of the community energy system or retain control of photovoltaic arrays on their rooftop.


3. TYPOLOGIES Four typologies for retaining control of renewable energy resources are identified below and illustrated using simplified line diagrams to indicate energy use and distribution. In all cases the icon of the sun represents any renewable energy source. They are divided into two categories: Direct and Distributed Energy Resources.




Figure 1: Diagram of a stand-alone renewable energy system.

3.1. Direct: Individually owned and used For the most part, renewable energy systems in the built environment have been limited to single building applications, small-scale applications where energy is used directly. This configuration is generally referred to as “distributed generation” or “behind the meter generation” and encompasses not only renewable installations such as rooftop PhotoVoltaics (PVs), but also emergency power supplies such as backup generators fuelled by diesel oil or propane.




1. Non grid-tied / self-sufficient: A non grid-tied settlement generates and uses renewable energy to meet its own energy demand. Such a settlement, or individual residences within, generally use passive sustainable design features and are appropriately insulated to reduce energy demand. Renewable energy features may include PVs and/or wind turbines. Some incentives, including tax credits or low interest rate energy loans may be applicable. The 2002, 2005, and 2007 NREL Solar Decathlon Competitions simulated a non grid-tied community since the individual homes were collectively configured into a “Solar Village,” but each home was electrified by its own Building Integrated PhotoVoltaic (BIPV) system and excess energy was stored on-site for use when power was not being generated (fig. 1). For the most part non grid-tied systems should not be considered where reliable utility access exists. 2. Grid-tied / non-interconnected: A variation of the self-sufficient model is where renewable energy generates all or some of the electricity necessary to power an individual home or building. The balance of energy is provided through a connection with the utility grid. This configuration results in reduced energy bills, since not all electricity is purchased from the utility, serving as an incentive for building owners (fig. 2).





Figure 2: Diagram of a grid-tied, non-interconnected renewable energy system.




3. Grid-tied / Interconnected: In an interconnected scenario communication between the utility grid and the building works in two directions; balance of energy is provided through interconnection and excess energy generated is fed back into the utility grid (fig. 3). Prior to considering a grid-tied project in the United States, interconnection regulations and protocols must be investigated since many states are non-permissive or otherwise restrict tying into the utility grid. Feed-in tariffs (EU) or Netmetering is an accounting system for grid-tied renewable energy projects. These projects are provided with credits for surplus electricity that is supplied to the utility grid. Selling excess electricity to the utility offers cost savings compared to purchasing grid electricity from a utility and is a promising way to reduce the costs of installing community energy projects. Net metering regulations also vary widely in the US; although the 2005 US Energy Policy Act encouraged individual states to adopt net metering regulations, not all have done so. Those states that do allow net metering vary widely in the sell-back price as well as the procedures required to register with the utility as a net-metered customer. For the 2009 Solar Decathlon competition homes were grid-tied and extra points in the “Energy Balance” competition were awarded to teams that provided excess energy to the grid.

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Figure 3: Diagram of an interconnected renewable energy relationship where energy is generated from renewable sources on site and supplemented by the utility grid. Through interconnection, excess energy generated is fed back into the utility grid.

3.2. Distributed Energy Configuration:

Resources

(DER)

For renewable energy to have a more significant impact in realizing carbon-neutral goals installation at the community (neighbourhood) scale must be considered in a distributed energy resources (DER) configuration. DER provide benefits of a centralized system, generating and distributing power, but have distinct characteristics that are locally beneficial: 1) DER are smaller in size than typical power plants; 2) they are located near customers and serve individual or small groups of customers; and 3) they are generally modular and scaleable, utilizing off-theshelf technology that can be scaled up as demand increases [3].




4. Micro-grid connected community: This type of community consists of energy-efficient buildings where all or some energy is produced by renewable energy (fig. 4). The community is connected by a localized grid and interconnects with the utility grid at a single point. Potential for increased ownership and control of the project are advantages of a micro-grid for a community-based energy project. Incentives for such a model are in the form of government grants that help offset the costs of establishing the micro grid. Tax credits may apply to individual buildings and serve as an incentive for people to buy into the community. A benefit of the micro-grid configuration is that renewable energy may be used in a community even where all buildings are not ideally oriented. A major barrier to the deployment of microgrids in the US is the fact that no state has a legal definition of a micro-grid. As a result, even where micro-grids have the right to exist their legal status could vary based on the interpretation of the utility regulators or the politicians who appoint them.




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Figure 4: Diagram of a micro-grid configuration where all or some energy needed for the community is produced by renewable sources and the community is connected by a localized grid that interconnects with the utility grid at a single point.

A successful variant of the micro-grid model is being implemented in the state of Maine, USA. The Fox Islands community-owned wind project provides electricity to the island residents and sells surplus power directly to the New England transmission operator through the wholesale market, rather than to an electric distribution utility. The Fox Islands project was able to side-step interconnection negotiations with the electric utility because of its relatively large size (4.5 MW) for a community-scale energy project. The island community has begun experimenting with the use of distributed thermal storage to “store” surplus wind power for heating and hot water, thus reducing the need of the island residents to import fuel oil or propane from the mainland [4] [5]. Deployment of micro-grids require significant expertise and capital investment beyond the source of the power supply, since inherent in the micro-grid is the existence of a local electricity distribution network. In the case of Smethport, Pennsylvania, a biomass CHP system that will provide electricity and district heating to the existing town is being considered in the context of an expensive infrastructure replacement project. Inspired by a similar initiative in the town of Gussing, Austria, Smethport is planning to construct a biomass reactor fuelled by low-grade timber (low-value wood that would otherwise be discarded as waste). The economics of the project are appealing, and local technical expertise exists since the municipality owns some of the electric distribution assets within the community. The project will also help the town meet its environmental and economic development goals, since providing fuel for the biomass plant will help support the town’s timber workers [6].

4. LESSONS LEARNED Through analyzing the various case studies across Europe and the United States certain common lessons were learned that, while not absolute, might be useful in establishing guidelines




PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

for the design of renewable sustainable communities [7]:

energy-based

4.1. Integrative Design One of the main factors required for a successful community is the need for an integrated design approach. This requires project stakeholders and agents to be involved in the design process, especially in setting and agreeing upon clear project goals and objectives at the outset. Coordination to attain these goals must take place throughout design and construction. Additionally, experience plays a significant role in the realization of complex community-scale energy projects. For example, in the case of the Nieuw Sloten PV houses (The Netherlands, Amsterdam) where leaking occurred in some of the PV roofs due to the complexity of the field conditions and lack of experience by the installer in both PV installation and in roofing [8]. Another example is the ‘City of the Sun’ (Stad van de Zon) also in the Netherlands. Although “from a purely technical point of view, there were no problems in the design and realization of the project,” barriers in the process included “lack of knowledge of PV by the urban designers” and some of the architects considering “PV as a design limitation rather than a challenge.” As a result, PVs were not always a priority and in some cases designs were produced that “were unsuitable for PV” due to inappropriate orientation, structure and shading [9]. New communities are already learning from these cases and trying to involve all the concerned parties from the very start. This is evident in the approach taken by ARUP for the design and development of the Low2No project in Helsinki. They followed a methodology of:
Setting objectives at the very outset;
Integrating processes like economics and environment to identify synergies and benefits early on;
Involving the client at the core of the development process through workshops and meetings; and;
Carrying out testing and inspection of systems to have a level of accountability. [10] 4.2. Community Participation Community Participation is an extension of the integrative design approach and involves getting the community involved in setting goals and aspirations for the project. Such participation was evident in the Sustainable Model City District Vauban (Frieburg, Germany) where a NGO called Forum Vauban was formed to foster participation between the planners and community. This was particularly helpful in bringing citizens to the table and brainstorming creative ideas that helped overcome the obstacles the planners were facing with regard to traffic [11]. 4.3. Changes in Policy Lack of government support, both for project funding and as incentive for investments in training and education, has lead directly to lack of

competency in the implementation of renewable energy, significantly in North America, but also in Europe where existing incentives are constantly threatened by changing politics. These trends affect project cost, relating directly to funding sources, and potentially the success of a community-scale renewable energy project. 4.4. Multiple Funding Sources It is evident from the case studies that the cost for renewable based sustainable communities is quite high and that despite incentives it is hard to raise project funds from a single source. Multiple sources to raise the necessary finances can be a mix of equity and debt. The projects at Rieselfeld, Germany and Fox Islands, Maine, USA, are examples of multiple and varied sources of funding being used. The Rieselfeld financial model was based on government incentives and tax credits along with the main funding from the City through a trust account covered by the KE LEG GmbH. Rieselfeld saw state support for residential construction discontinued and tax advantages for investors cut. However, in this case the financial model was tweaked to allow small investors as well as private and industrial groups to buy into the community. This helped to eventually develop the community and has keep demand strong even today [12]. In the case of Fox Islands, it was a combination of PTC/ITC funding and RUS debt financing at a fixed rate of 4% for 20 years that made the project viable [13].


4.5. Post-Occupancy Maintenance Loss in energy efficiency due to a lack of post occupancy maintenance was another problem recognized in some the case studies examined, adversely affecting overall energy performance. Post occupancy maintenance problems were foreseen in the proposed Port of Barrow redevelopment project (Barrow, UK) where community-member’s feared that energy saving and PV features would be eliminated by the developer to cut costs or not maintained by the homeowners over time. Although these are difficult problems to address, innovative measures were considered to counter these problems including implementing planning restrictions to prevent energy-saving fixtures from being removed and establishing procedures for educating homeowners about long-term benefits of maintaining energy-related features including PV [14].

5. CONCLUSIONS / NEXT STEPS: For successful implementation of community-scale renewable energy projects, zoning regulations that are consistent with energy development goals need to be devised. Zoning regulations and property rights must be designed especially carefully if the desired system is distributed in nature (such as a community with multiple rooftop solar installations). Since a building with a rooftop photovoltaic installation may be affected by nearby tall buildings or trees, “solar

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shadow” regulations that provide some property rights related to rooftop solar have been adopted by a couple of states [15]. Homeowner covenants can also be designed with energy goals in mind. For example several of the projects studied separated rooftop ownership from control to ensure that community managers had access to install and maintain renewable energy systems. The preliminary research results included in this paper will be used by this team to develop spatial guidelines that will reveal principal modes of interaction between buildings and energy systems by summarizing findings related to physical form in a series of schematic diagrams. Building orientation and relationships relative to different renewable energy implementation strategies will naturally be important to our spatial representation approach, but other decision-making dimensions, including regulatory considerations (ie. innovative zoning strategies, ownership/management models and property rights and homeowner-association covenants), will also be researched and incorporated. The resulting guideline will present high-dimensional visualization information that integrates built physical form with economic, regulatory, and policy-relevant implementation factors.

6. ACKNOWLEDGEMENTS The research and finding summarized in this paper was supported by a grant from the Pennsylvania State University College of Arts and Architecture Competition for Faculty Research Grants program in 2009-2010.

7. REFERENCES [1]

D. W. Aitken, ‘Transitioning to a Renewable Energy Future’, International Solar Energy Society (ISES) White Paper, Frieburg, Germany, (2006).

[2]

The benefits of distributed energy related to CHP are summarized in a U.S Department of Energy report (2007) available at : . Other reports including Carlson and Hedman 2004, Bailey et al. 2002, King and Morgan 2006, Pepermans, 2005, Poore et al 2002, summarize advantages to customers.

[3]

D. King, Discussion of distributed generation and distributed energy resources as distinguished from centralized generation from Electric Power Micro-grids: Opportunities and Challenges for an Emerging Distributed Energy Architecture. PhD Diss., Carnegie Mellon University (2006), Pp. 130-131.

[4]

The VCharge Transactive Energy Management website has details of VCharge Wind Integration Fox Islands Smart Grid Project, Fox Islands ME, (Fall 2010 through Spring 2011). .

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[5]

L.D. Iulo, J. R.S. Brownson, S. Blumsack, R.A. Kimell, ‘Potential and Implementation Strategies for Renewable Energy in the Planned World’, Interdisciplinary Themes Journal, vol. 2, no.1 (2010).

[6]

S. Williams, Reinventing Smethport, (2009) .

[7]

B. Gaiddon, H. Kaan, and D. Munro, (ed.), Photovoltaics in the Urban Environment: Lessons Learnt from Large-Scale Projects, Earthscan, London, Sterling VA (2009).

[8]

J. Cace, and E. t. Horst, ‘The Netherlands, Amsterdam, Nieuw Sloten PV houses’, in Photovoltaics in the Urban Environment, eds B Gaiddon, H Kaan, and D Munro, Earthscan, London, Sterling VA (2009), pg.58.

[9]

M Elswijk et al, ‘The Netherlands, HAL location ‘City of the Sun’, in Photovoltaics in the Urban Environment, eds B Gaiddon, H Kaan, and D Munro, Earthscan, London, Sterling VA (2009), pp70-71.

[10] Website has details about the project, ARUP, ‘C_Life City as Living Factory of Ecology’ (2010, . [11] C. Sperling, ‘Sustainable Urban District Freiburg-Vauban’ (2002), . [12] Energie Cities, ‘Rieselfeld: quality and local life combined’,. [13] G. Baker, ‘Fox Islands Wind: A Case Study of Community Ownership’ (2010), . [14] D Munro, ‘UK, Barrow, Port of Barrow redevelopment, in Photovoltaics in the Urban Environment, eds B Gaiddon, H Kaan, and D Munro, Earthscan, London, Sterling VA (2009), pp135-136. [15] Information, including a list of relevant States, is available from the U.S. Department of Energy U.S. Department of Energy Energy Efficiency & Renewable Energy, “Solar Powering your Community: A Guide for Local Governments (2009), .

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Technologies and Sustainable Policies for Decreasing Energy Consumption in Buildings in Greece N. PAPAMANOLIS, M. MANDALAKI Department of Architecture, Technical University of Crete El. Venizelou 127 (Former French School), 73133, Chania, Greece ABSTRACT: This paper investigates and introduces the present situation regarding energy consumption in buildings in Greece. Based on the available statistical data, it evaluates the energy behaviour of corresponding buildings. It also describes the measures and the practices which are applied in the country to reduce the consumption of energy in the building sector. It includes references to the existing legal framework, the prevailing design and construction practices, the construction materials etc. It also examines and suggests measures that could help to improve the framework of energy consumption in buildings in Greece. Keywords: Sustainable technology, Sustainable policy, Building, Greece

1. INTRODUCTION Greece, with an overall land area of approx. 2 132,000 km , consists, by the four-fifths of its mainland, of mountainous terrain. Greece is also a maritime country with numerous islands and a coastline of over 15,000 km in length. The bulk (i.e. about 59%) of the country‟s population which, according to the estimation of the National Statistical Service, stands at about 11.3 million, lives in urban areas [1]. Most urban centres and the largest of them, including the conurbation of the capital, Athens, with its population of about 4 million, and the second largest city, Thessaloniki, with its population of about 1 million inhabitants, lie on the coast. Greece has a Mediterranean climate [2]. According to the relevant climatic data, the annual cycle can be divided into a cold and rainy season (October to March) and a warm and dry season (April to September). Temperatures on the Greek mainland present intense contrasts mainly due to geographic factors. Greece is between the average annual isothermal of 14.5 and 19.5 °C. The extreme temperatures are close to -25 °C (during winter in the mountainous and northern regions) and +45 °C (during heatwaves on the mainland). The mean relative humidity ranges from 65% to 75%, according to location. It displays a simple annual fluctuation, with the maximum occurring during the winter months, and depends on the proximity of natural concentrations of water. In Greece, the general circulation of the atmosphere and the prevailing synoptic systems in the wider area contribute to the prevalence of western and northern wind components and fairly moderate speeds. However, in interaction with them, the complex relief of Greece plays an important role in determining the prevailing wind direction and speed in many regions. Greece is a very sunny country. The average annual rates of incoming solar radiation, moving from north to south, range 2 from 5000 to 6100 MJ/m /yr [3]. The climatic data

above relate mainly to the countryside. In urban environments, in which the majority of buildings are situated, these data change as a result of the influence of the factors which make up the urban climate [4]. Buildings in Greece, according to statistics for 2008, consume about 39,8 % of the total annual energy consumption [5], while, of this amount, the energy consumed in households (for space heating and cooling, water heating, lighting etc.) is estimated to be about 61% [6]. The energy consumption of the building sector in Greece, on the basis of the statistics of recent years, has a upward trend (from 6.21 Mtoe for 1997 to 8.45 Mtoe for 2008), understandably, as a result of the increase in the number of buildings and the energy-consuming applications and in particular air conditioning systems in them [7]. Buildings in Greece are wasteful in energy terms. It is interesting that, while the country is in the southern area of Europe, the percentage representing the energy consumptions of building sector over the total is close to the mean value of all 27 EU countries (40.8 % for 2008). Also, based on the climate corrected household energy consumption for space heating, 2 Greece, with about 21.5 Kgoe/m for 2005, is ranked first between all the European countries [8]. The factors influencing energy performance of buildings in Greece, under the particular climatic conditions, are more or less specific, similar throughout the country and outlined [9]. These factors remain unaltered during the last decades. More specifically, neither the way that buildings are designed and constructed, nor the behavior of their users - in what concerns the building‟s energy performance - has changed dramatically during this time. In this respect, it is indicative that the regulatory framework remains essentially the same since 1979. Unsuccessful efforts for its improvement have been done in the past. It is only since October of 2010, that the application of a set of measures for the improvement of the energy performance of buildings

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in Greece started, in order to apply the EU Directive 2002/91/EC. This study briefly describes the present situation in terms of energy performance of buildings in Greece. The most important factors that influence this situation are emphasized. The biggest part of the study focuses on the principal practices and measures currently proposed and applied in order to reduce energy consumption in buildings in the country.

2. THE MAIN DATA FORMING THE ENERGY BEHAVIOR OF BUILDINGS IN GREECE In Greece, the vast majority of buildings - above 90 % - are residential buildings [10]. Second in terms of frequency comes the category of buildings housing productive activities, which are commonly known as commercial buildings (housing commercial operations, services etc.). In constructional and architectural terms, this category displays many similarities to the previous one. The smallest group includes buildings housing social services or functions (schools, hospitals, meeting halls etc.) and buildings serving special uses. In this category, the greatest variety of architectural forms is to be found, despite the fact that the basic constructional characteristics of corresponding buildings are the same as those in the other two categories. The concrete, perforated bricks and other building materials, as well as the building practices that prevail in the construction of buildings in Greece, have a direct impact on their energy behaviour. Thus, the great heat capacity of the building materials, the low air permeability of the envelopes, the presence of thermal bridges, the high levels of fire resistance and mechanical resistance, as some of the typical properties of the particular construction model used, of course play a role in shaping important parameters in the behaviour of the buildings concerned. So, too, do those properties relating to thermal conductivity, moisture permeability, sound-insulating power and other parameters of the construction elements. The quality of construction of buildings in Greece, at least during the last few decades, has, by and large, been average. The building materials that are used and the practices that are applied, with regard mainly the invisible surfaces of buildings (such as layers of insulation) are often governed by a rationale of low cost and ease of application. The underlying causes of this reality can be sought in different areas. Its consequences, however, are reflected in building pathology issues and of course in the low performances of the buildings in terms of their energy behaviour [9]. Another important group of factors affecting the energy performance of buildings in Greece concerns the way that users behave in the buildings in which they live or work. One aspect of this behaviour includes the attempt of constructors to exploit the weaknesses of the existing system of building construction in order to make financial gains at the expense of the quality of construction. Another important aspect of the user‟s behaviour concerns his active intervention in processes that influence the

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behaviour of the buildings they live in. In this area, although no available data exists, it can be assumed that the Greeks are by and large insufficiently sensitized. The way in which they face their role in the energy behaviour of buildings is rather superficial and their conduct in this respect could be described as being based on reflex actions. For example, the actions they take to control the parameters of the internal environments of their buildings, rarely go beyond using the available electro-mechanical installations [9]. The principal piece of legislation that concerns the energy behaviour of buildings in Greece was until the October 2010 the Thermal Insulation Code. The Code, which has been in force since 1979, provides for three stages of assessment and control in respect of thermal losses in buildings. The first stage concerns the thermal properties of the different building elements in the envelope. The second stage concerns the mean heat transmission rate of the building‟s envelope on each floor. The final stage monitors the mean heat transmission rate of the overall surface of the building‟s envelope. In this respect, the country is divided into three climatic zones and for each zone the Code provides for a maximum mean heat transmission rate, which ranges 2 from 0.616 to 1.553 W/m K, in relation to the ratio between the volume and envelope surface area of each building [11]. A large proportion of buildings in Greece were built before the Thermal Insulation Code came into effect and do not possess thermal insulation of any kind. It has been estimated that the average heating energy demand of Greek apartment 2 buildings built before 1980 is about 96 kWh/m , while for those built after 1980 the demand is estimated to 2 be between 75-94 kWh/m [12]. A second important piece of legislation with provisions relating to the health and comfort of occupants, the protection of the environment and energy saving in the building sector in Greece is the Construction Code for Buildings [13]. This Code deals specifically with the natural lighting, ventilation, damp protection, sound insulation and fire protection of buildings, amongst other things. In the recommendations that it contains, the Code uses mainly qualitative criteria; wherever quantitative criteria are used, these relate indirectly to the physical magnitudes of the phenomena being examined (e.g. the dimensions of openings for natural lighting or ventilation). A drawback for the Code, which renders many parts of it ineffective, is the lack of legislation concerning their implementation. An attempt has been made to improve the legislation relating to the environmental and energy behaviour of buildings within the framework of the national programme called „Energy 2001‟ [14]. This programme was the main measure taken to comply with the EU Directive 1993/76/EC (SAVE Directive). A key action of „Energy 2001‟ was the elaboration of a new national building energy code which would replace the existing Thermal Insulation Code. Additionally, it was introducing the legislation of building construction standards, promotion of renewable energy in building construction and refurbishment, energy certification and energy audits of buildings, as well as specific, obligatory energy-

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

saving measures for public buildings. Legislation supporting the programme was never completed.

3. CURRENT POLICIES REGARDING ENERGY MANAGEMENT IN THE BUILD ENVIRONMENT IN GREECE Greece incorporated the EU Directive 2002/91/EC on the Energy Performance of Buildings [15] with the Law 3661/2008 “Directions for reducing energy consumption in buildings and other regulations”. For its implementation, the law entitled: “Energy Efficiency Building Regulations” has been published on the 9th of April 2010 and it is active since the 1st of October 2010 [16]. It is important to note that, while the EU Directive‟s application was planned for 2003 and for Greece this date was postponed for the end of 2006 [17], the actual activation of the Directive came in force 4 years later. With the announcement of the “Energy Efficiency Building Regulations” (EEBR), sustainable design and construction has been typically introduced in Greece. This has been done in order to improve all buildings‟ energy efficiency, their energy savings and to protect and preserve the natural environment. These goals are achieved through four basic actions: 1. The legislation of the energy efficiency study. 2. The introduction of minimum standards for a building‟s energy efficiency. 3. Buildings‟ energy classification that leads to a Building‟s Energy Certificate. 4. The Building‟s Energy Inspection, and the Inspection of its Technical Systems (the boiler system, heating system and air conditioning). The Energy Efficiency Study is replacing and abolishing the Thermal Insulation Code. This study is necessary for the building permit of every new 2 building over 50m and for all existing buildings that will be renovated. This study is based on a specific methodology with two main steps: a. The implementation of required standards for the examined building in terms of design, performative quality of its envelope and quality of its technical systems (heating, cooling, ventilation, hot water, lighting and combinations of them). b. The comparison of the examined building with a reference building. The reference building is a model building with the same geometrical characteristics, the same site position, orientation, the same use and operating characteristics with the examined building. It also follows the minimum energy requirements and has specific technical characteristics. The total primary energy consumption of the examined building should be the same or less than the primary energy of the reference building. The examined building (new or existing that requires renovation), has exactly the same technical characteristics and consequent energy performance as the reference building. Building Energy Performance Certificate indicates the energy performance of a building and classifies it into one out of nine categories. The Certificate is 2 mandatory for all new buildings over 50m or buildings that are being renovated. It is also 2 necessary for buildings over 50m that are about to be rented or sold and for all public buildings. This

Certificate is valid for ten years. In the case of rented or sold buildings, the Certificate is required from the 9th of January 2011. The results of the report of the energy inspector are among the information inscribed on the building Energy Performance Certificate. On the same Certificate, there are recommendations for the improvement of the energy efficiency of the building in such a way, that users can compare and assess their energy consumption and recognize any opportunities for energy efficiency improvement of their building. The Building Energy Inspection is the basic tool for the evaluation of the Energy Performance of existing buildings and for the recognition of the potential of their energy consumption improvement. All certified buildings‟ Energy Performance Inspectors belong to the general records of the Greek Ministry of Environment, Energy and Climate Change and are the only ones certified for the Energy Inspection and the approval of the Energy Performance Certificate. They inspect the existing buildings and produce the building Energy Efficiency Study, in order to assess the examined building. This assessment is based on the ratio of the energy consumption of the building to the energy consumption of the reference building. In order to become a certified Energy Inspector, an engineer should: a. have at least four years of professional or research experience in building design and/or in energy savings systems and b. attend the certified seminar organized by the Technical Chamber of Greece and pass the exams. The seminar should be at least 60 hours in order to become buildings‟ inspector and 30 hours for the case of technical equipment and air conditioning systems inspection. The general management of the application of this framework is being held from the Special Service Energy Inspectors and is under the supervision of the Ministry of Environment, Energy and Climate Change. There are multiple benefits from the implementation of the EEBR law. These are financial, social and of course, environmental. The financial benefits occur because of the reduction of the operating and maintenance costs of the buildings and because of the expected revival of the building industry sector. The social benefits are connected with the creation of new working places and the improvement of the quality of life. The environmental benefits concern the reduction of dioxide emissions and especially of CO2 emissions, the stabilization of climate change and the reduction of energy consumption form non renewable sources. In order to create motives for energy savings in the building sector, the Ministry of Environment and Climate Change in collaboration with other institutes, has prepared two basics action programs : a. “Energy savings in the housing sector” and the b. “Building the Future”: a. The first action concerns subsidies for energy upgrading housing buildings. It refers to three categories of owners, according to their income. The lower the income of the owner, the higher the subsidy and the percentage of the interest-free loan, offered [18]. b. The second action is going to enter into force on 2011 and finished on 2020. It concerns the reduction, of energy consumption in build

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environment, of the financial costs for building owners for the energy upgrade of their building and of the operating cost of the building. It is focus on integration of advanced technology for energy saving in buildings, on demonstration and construction of zero energy buildings and on research actions for design of high- tech environmental efficiency products [19]. The new legislative framework for the Energy Performance of Buildings in Greece has a lot of features that make it seem promising. But during the first period of its entry into force, defects and abeyances that create difficulties in its application have been noticed. For example the deadline for applying for a position of temporary Energy Inspector was after the date of entry into force of the EEBR (1st October) and till now (middle of February), the educational process of the formal Energy Inspectors has not been clarified. The only educational process that has been organised till now is unofficial seminars conducted by the Technical Chamber of Greece, in order to inform the temporary Energy Inspectors and the Energy Consultants. It is important to note as well, that the information of the Engineers and all others involved in these processes (for example buildings‟ owners), about these new measures, has not been as profuse as their importance imposed.

4. CONCLUSIONS According to the statistical data, energy performance of Greek buildings is low. Based on the fact that the climatic conditions of the country are mild, the reasons for this unpleasant reality should be searched at the quality of the buildings‟ design and construction and at the users‟ energy behavior. Indeed, the average design and construction quality as well as the low sensitivity of buildings‟ users in terms of energy savings, have been defined, among other reasons, as the most important facts influencing building energy performance in Greece. Nevertheless, the intervention for optimizing the buildings‟ energy performance was delayed for several decades, despite the fact that the reasons that till now were contributing to the energy wastage, in them were already known. The second semester of 2010, an ambitious legislation package and other related initiatives began, in order to upgrade the energy performance of buildings in Greece. Energy measures and actions that have been taken, in accordance with relative EU‟s directives and support, have not been tested yet. Some problems in the beginning of the application of these measures have already been noticed and can justify the negative critique about some aspects of them that have not been sufficiently studied. However, the main subject that has to be clarified is the compatibility of these legislation measures to the local conditions. Is important, that, these new measures, that intend to upgrade the energy building performance of the existing building stock, could be supplemented with others that will directly help the way that buildings are designed and constructed in the country. These new measures, in order to be effective, should cover all the production chain of

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buildings (including education of all specialists involved in the building industry and detailed control of building construction) and, primarily, should be based on the specific climatic and environmental conditions in Greece.

5. REFERENCES [1] http://www.statistics.gr/portal/page/portal/ESYE [2] http://www.hnms.gr/hnms/english/climatology/cli matology_html [3] A.A. Flocas (1980), Estimation and Prediction of Global Solar Radiation over Greece, Solar Energy Journal, Vol. 24 (1), 63-70. [4] H. E. Landsberg (1981), The Urban Climate. Academic Press, London. [5] http://epp.eurostat.ec.europa.eu/tgm/table.do?tab =table&plugin=1&language=en&pcode=ten00101 [6] http://epp.eurostat.ec.europa.eu/tgm/table.do?tab =table&init=1&language=en&pcode=tsdpc320&pl ugin=1 [7] http://www.cres.gr/energy_saving/Ktiria/ktiria_intr o.htm (in Greek). [8] http://www.eea.europa.eu/data-andmaps/figures/household-energy-consumptionspace-heating-perm2-climate-corrected [9] N. Papamanolis (2006), Characteristics of the Environmental and Energy Behaviour of Contemporary Urban Buildings in Greece, Architectural Science Review, Vol. 49 (2), 120-126. [10] http://appsso.eurostat.ec.europa.eu/nui/show.do? dataset=cens_rdhh&lang=en [11] Hellenic Ministry of Environment, Planning and Public Works: Thermal Insulation Code for Buildings, Decree-Law 1/6/1979, The Hellenic Official Gazette, 362D, 1979. [12] C.A. Balaras, K. Droutsa, E. Daskalaki and S. Kontoyannidis (2005), Heating Energy Consumption and Resulting Environmental Impact of European Apartment Buildings. Energy and Buildings, Vol. 37 (5), 429-442. [13] http://portal.tee.gr/portal/page/portal/teelar/NOM OTHESIA/KTIRIOOIKODOMIKOS%20KSNONIS MOS (in Greek). [14] Hellenic Ministry of Environment, Planning and Public Works: “Energy 2001”: Action Plan for Sustainable Construction, Athens, 2001. [15] http://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ: L:2003:001:0065:0065:EN:PDF [16] http://www.ypeka.gr/LinkClick.aspx?fileticket=aiS 4GyKxx04%3d&tabid=525&language=el-GR (in Greek). [17] International Energy Agency, Energy Policies of IEA Countries, Greece 2006 Review, p. 164. [18] http://www.ypeka.gr/Default.aspx?tabid=526&loc ale=el-GR&language=en-US (in Greek). [19] http://www.ypeka.gr/Default.aspx?tabid=362&sni[ 524]=637&locale=en-US&language=el-GR (in Greek).

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Building Regional Intelligence Christopher DOMIN, Larry MEDLIN, Brent D. VANDER WERF University of Arizona, College of Architecture and Landscape Architecture Tucson, Arizona USA ABSTRACT: The SEEDpod dwelling prototype enters into a pact with nature as it interacts with local climatic conditions. The envelope creates a selective filter, which protects the interior from varying environmental conditions. Active and passive elements include a 9 Kw photovoltaic roof array, operable wall assemblies with insulated panels and glazing systems with ventilation options. The primary objective is to provide a compact, highly efficient building strategy that can advantageously interact with natural forces. A remedial engagement with the local environment provides further direction for our performance-based design process. The intention is to literally grow liveable interior and exterior spaces. An important catalyst for the development of regional building intelligence at the University of Arizona: College of Architecture and Landscape Architecture is the design studio with associated materials laboratory. Research prototypes developed in this empirically engaged setting of thinking, drawing and building are artefacts of a uniquely integrated way of working. Iterative development over time in service of both the particular condition of experimentation and also comprehensive final integration into a full-scale assembly is imperative to the method. Prototype system development is the focus of this presentation, along with fabrication and assembly of a dwelling unit. Research and development programs at both the graduate and undergraduate level became essential components of the fully operable prototype: a pivoting structural rib assembly, which facilitates adaptability to optimum solar incidence, a compliant shading system that registers the movement of light throughout the day, and the thermally tuned water wall. Prototyping, performance analysis and implementation of the compliant shading system within the holistic framework of the building envelope is the focus of this investigation.

attuned to the natural climatic cycles and unique ecological niches and micro-environments of their dwellings. Drawing from this acquired awareness, the inhabitants became progressively more efficient in the use of energy and other resources during the subtle operation of daily life. This inspired a goal of the SEEDpod team to create a dwelling that would facilitate the development of human intelligence and wisdom attuned to a unique climate and ecological environment [1]. In Southern Arizona and Northern Mexico the Sonoran Desert’s clear skies with limited cloud cover offer large diurnal temperature swings of over 30°F throughout the year. This results in comfortable outdoor ambient temperature conditions during select seasonal conditions. In this context, natural energy forces of solar radiation and air movement can be utilized in passive environmental design strategies to create advantageous microenvironments for indoor/outdoor living. Comfortable ambient environmental conditions frequently occur during winter days, early summer mornings and evenings and often throughout the day during the spring and fall. Historically we have built to overpower nature with minimal concern for environmental impact. Recognition of, and a desire to, advantageously utilize the unique characteristics of the Sonoran Desert climate and the ecology of each site were key considerations during the conceptual design phase. The outcome is intended to provide residents with a tool for engagement and interaction with the specific microclimate and natural elements of its location— these include the sun used to create electricity, heat water and air and to provide daylight; water harvested for domestic needs and irrigation of edible plants and landscaping; and air used for ventilation and maintain a healthy environment [2].










 Keywords: sustainable building, desert architecture, regional technology, materials research, bimetals, shade

1. INTRODUCTION Drawing from experience with multiple passive solar design residences, members of The University of Arizona SEEDpod design team recognized that residents, over a period of time, became more





 Figure 01, SEEDpod perspective.




Much recent thinking of value engineered energy efficient buildings has led to airtight,

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unplanned for cross ventilation, poorly day lit, highly insulated environments. Some are fully automated systems with limited or no possibility for occupant interaction in operating the systems. A few have even suffered from sick building syndrome [3]. A primary objective of the SEEDpod is to provide a compact, highly efficient dwelling, which includes mechanical, kitchen, bath and workspace modules in a continuous core that frees the remaining open floor plan for adaptable use of space. This enables SEEDpod residents, as desired, to easily interact with surrounding spaces and natural forces. The intention is to facilitate the growth of liveable outdoor spaces. A detached green house module on the northeast will serve as a biofilter and provide edible food products. The large pivoting doors will permit moving the bed outside during summer nights to the western deck for sleeping under the stars and the clear (radiant) night sky. Similarly, an expandable table component of the kitchen counter can be moved to the eastern deck for outdoor dining and other activities.

water can be cooled by taking advantage of the large diurnal temperature swing at night. This water can be introduced into the tanks at night and then into the water wall the next day to absorb heat from the ambient air in the space. The north, east and west walls have zinc clad insulated panels with operable doors and windows that can be opened to facilitate and control cross ventilation.

2. STUDIO ~ LABORATORY A majority of the building components incorporated into the SEEDpod were developed through extensive student/faculty research and iterative prototype development. The design and construction phase took place over a two-year period and utilized the architecture studio as a place of hypothesis development and the materials laboratory as the site of continual testing and proof.
















 







 








Figure 02, SEEDpod with Compliant Shading System installation: exterior view.

. The SEEDpod is designed as a selective filter that operates to advantageously interact with its natural climatic context. It consists of a series of skin systems, that can be operated to collect solar energy, harvest water and control ventilation. The optimally sloped southern facing roof is sheathed with photovoltaic solar panels that produce electricity for the dwelling and above the mechanical core an array of evacuated cylinders provides hot water for the dwelling. The solar panels power a heat pump that provides heating or cooling during periods of high heat and/or humidity and cold nights. However, Tucson’s low humidity and large diurnal temperature swings will permit the system to be operated in a vent only mode or turned off with fenestration opened to allow cross ventilation. The south wall consists of insulated glazing and a vacuum formed and vacuum filled water wall made from recyclable and UV resistant PET plastic. The water, which has three times the thermal mass capacity of brick or concrete, will absorb the sun’s energy during the day and reradiate it to the interior space at night. In Tucson, when cooling is desired,

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Figure 03, SEEDpod full-scale prototyping in CALA Materials Laboratory.

Multiple ground-up research projects dealing with the thermal envelope and modular construction were integrated into the final full-scale working prototype. Utilization of digital fabrication, vacuum forming and traditional wood, metal, fabric and glass fabrication techniques allowed the team to develop, refine and test prototypes in a single location. Some of the most challenging issues confronted during project development were thermal performance, cost of final production, ability to produce at a logical scale within a marketable demographic, refinement of details to meet production goals, and transportation limitations. The quality control procedures implemented in the materials laboratory along with exacting engineering standards allowed for the integration of individual research initiatives within the larger structural framework. The final dwelling unit is comprised of a durable material palette and advanced thermal

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

envelope, which will allow for long-term testing in the Sonoran Desert.

3. COMPLIANT SHADING SYSTEM

3.1. Overview The compliant shading system investigates elastic structures and materials in terms of mechanical and physical properties for the design of a bi-stable (capacitor) mechanism, which is programmed to deform an aperture. The design of the apperture promotes compliance to variable radiant-energy sources while providing passive shade and thermal comfort regulation [4]. Elastic properties, precedents and materials were studied and modeled to identify the maximum stress and strain force by which materials and structures were capable of deforming and returning to an original size and shape without permanent deformation a material characteristic known as the elastic proportional limit. Bi-stable structural mechanisms, organized with elastic spring steel strips and pin connections, form an aperture or eyelike opening, and are investigated as a capacitor. The capacitor functions through the pre-stressing of the spring steel strips, which, when paired with a thermostat coil, deform the apertures through diurnal thermal loads from the sun. The increasing storage of elastic strain energy is programmed to rotate and close the aperture at a maximum stressed position, at which point, it is capable of releasing the stored kinetic energy with a decrease in heat input, triggering the mechanism to open the aperture instantly. The arrangement of the self adjusting shade system is organized and manipulated spatially through a variety of prototype developments as a passive glass enclosure for the east and west facades of buildings. The University of Arizona’s SEEDpod prototype dwelling was used as a testing platform for the final iteration, which allowed for the evaluation of its performance, function and value as a potential building component. To comply, can mean to adapt, respond or agree based on a requirement or direct request. In terms of the external environmental and its influence on buildings and structures, architects and engineers are often required to comply with certain regulatory codes, both regionally and internationally, to control the interior environment of buildings for the health and well being of the user. A few examples of control that relate to this study include: providing and controlling light between interiors and exteriors; protecting the structure and inhabitants from rain, sun, snow and extreme temperatures; and controlling the interior HVAC environment for human comfort with mechanical systems [5]. The ability for the design of a building to comply to modern regulations set forth without means of electrically controlled, monitored or managed systems is rarely found as an option in building components and devices. However, as a method,

this strategy should not be ignored. Advancements in knowledge associated with material science and its relationship to physics and other environmental responsive stimuli has influenced many contemporary artists, engineers and architects to push the boundary of designs which have a direct effect on its surrounding or user by means of passive, non electrical means. The research associated with the Compliant Shading System is one of these passive responses and the study investigates a particular way in which light and shade can be controlled between an exterior and interior condition based solely on the energy from the sun. 3.2. Research Methods and Prototypes The research began by considering the following question— how can an enclosure be designed and organized structurally to comply to the sun, both diurnally and annually, in order to produce shade when required? The sun’s light rays are electromagnetic wavelengths with variable frequencies from which a constant level of thermal radiation is transmitted. The amount of radiation which reaches a given body of material is dependent on the angle of incidence against the body’s orientation. Throughout the day, the amount of thermal radiation will vary greatly from sunrise to sunset and through a deductive process the ability to track the sun is a possible by quantifying the amount of radiation reaching a particular surface or material for a set time. Furthermore, given that the sun’s incident energy acts on all objects each and every day, thermal expansion and contraction properties inherently occur as well and are directly associated to all materials based on density, color, surface properties, and molecular structure. A magnitude of force is thus present in all movements. Thermal expansion provides a consistent and definable passive action to appropriately quantify the amount of thermal radiation present on a body. Given this foundation and known dependent variables for solving a problem, an initial hypothesis was defined: If smart materials possess characteristics of passively sensing or adjusting to external environmental stimulus, e.g. change in temperature, light intensity, etc., then the energy from the sun can actively adjust a smart material to regulate the transmission of light and heat based on the placement of the material in relationship to its region and environment. From the hypothesis, an iterative research methodology followed and included: membrane prototypes capable of opening and/or closing 'space' to regulate light; modeling and empirical investigations of structural systems to form an aperture; researching and testing actuation materials which exert a force solely based on the energy from the sun; and the physical forces associated with the pairing and tessellation of actuators with moving frames.

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3.3. Membrane Prototypes The research on membranes was aimed at discovering a fabric which could serve as the primary enclosure material. The intent was that the fabric could stretch, and strain by means of an adjustable frame, which, in turn would open and close pores that were cut into the membrane. The pores would then act as a functional performance property, allowing for air and or light to penetrate through the enclosure. In the end, nylon, silicone polyester and spandex fabrics were tested and the performance of the membranes ability to strain, open apertures, and recoil back to its original shape was determined to be successful. However, an appropriate dynamic frame which could deformed linearly and provide the force required to strain the membrane and produce the opening of the pores was unsuccessful, as it was assumed that the mechanism to deform the membrane was nonmechanical, and thus there was a design struggle to balance the required high strain force with the minimal non mechanical passive force (Figure 04).

shade. Once the sun was no longer on the surface, the mechanism would then release its stored energy and return or recoil to an open aperture.

Figure 06, Enclosure Model Digital Prototypes.

After numerous iterations of models, sketches and testing of the bistable mechanism, the empirical research concluded with a few missing variables related to system adjustment to passive solar exposure. These variables included: what is the actuator that rotates the strip?; and how does the membrane fit appropriately within the bi-stable mechanism? The focus shifted to finding the appropriate actuator, one which responds to the force required to deform the aperture and one that rotates the required angular degrees over an appropriate change in temperature. 3.5. Actuator

Figure 04, Polyester / Nylon Apertures - Laser Cut and Stretched.


 3.4. Bi-stable Modeling Bi-stability can be defined as a mode of deformation for a mechanism between stable and unstable states. Energy transfers from maximum stress, an unstable form, to minimum stress, a stabile form [6]. Figure 05 identifies the initial empirical modelling of a single planar bi-stable model, and Figure 03 illustrates digital modelling of the bi-stable planar frame in the form of an enclosure skin.

Figure 05, Bi-stable Model - CFRP Strips / Elastomer Pin Connection.

Numerous physical models failed during the process of organizing the bi-stable frame into an enclosure. It was realized through modelling that if single bi-stable unit could be offset and mirrored, it could produce an aperture, or large-scale pore with two bi-stable strips, that then could open and close as the strips were rotated. The aperture was thought of much like a camera lens or iris, which could adjust to the exposure of the sun, based on its orientation. Thus, as the sun was to be exposed to the mechanism, the strips would deform and overlap each other, providing a surface of continuous

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A variety of solar passive actuators were researched, including, linear expansive fluids, bimetals, and temperature responsive polymers, but in the end, a simple thermostat coil was determined to be the most efficient and productive thermally responsive actuator to deform and set the shade enclosure with a rotational motion. Figure 07 identifies the form and mathematical principles of a typical thermostat coil. Thermostat metals are composite materials, which consist of two or more metallic layers having different coefficients of thermal expansion. When the layers are permanently bonded together, the different coefficients of expansion between the metals cause the resultant shape to curve or deform when subject to a change in temperature. The bending of the material in response to temperature change is know as the flexivity of the material and is an inherent principle to all thermostat metals [7]. As the thickness and length of the coil is manipulated, a range of programmable regions or a series of change in temperature characteristics allows the design of the thermostat coil to comply to any climatic region.





 Figure 07, Bimetal Equations for Coils, Engineered Material Solutions [8].

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

3.6. Prototype Synthesis With the research objectives established, the beginning of a working prototype was no longer a theory but a tangible objective focused on the specific organization of research elements: bi-stable mechanism, bi-stable strip, membrane, actuator, and enclosure. Based on the previous research and tests, it was determined that the appropriate coil for a dry and arid region required a minimum 1.5 degree rotation per 1.0 degree Fahrenheit change. This would allow for a 90 degree angular rotation with a change in temperature of 60 degrees Fahrenheit. Both the angular and temperature degrees were over estimated for the system, allowing for adequate design tolerances throughout. An initial test began in the middle of the morning, 9:30am, with an internal temperature of 80 degrees Fahrenheit and an outside ambient temperature of 70 degrees Fahrenheit. Within, fifteen minutes the actuator had rotated the strip almost 30 angular degrees. The expansion of the coil continued to rotate the strips until the maximum internal temperature of 120 degrees Fahrenheit was reached in the sealed enclosure, while the outside temperature was recorded at 80 degrees Fahrenheit. At this point, the heat stabilized and the coil actuator did as well, reducing the aperture to a sliver, but not yet 100% closed. It was not until the sun had passed Solar Noon that the box was now in shade and the internal temperature began to decrease (90 F) and in turn opened the aperture. The test was repeated several times over the next few mornings and afternoons and yielded similar results. Figure 08 identifies the photographic documentation of the test. This concluded the prototype applications and research. The following section identifies the performance criteria and potential applications for the self-adjusting shade system in various forms, manipulating the scale, placement and performance functions to theorize on the optimal product.




Figure 08, Sequence of Movement, 9:30am-12:30 pm

.

3.7. Performance Criteria The performance goal for the compliant shading prototypes was to design an enclosure system, which simply adapts to exposure from the sun. With direct exposure to sunlight, the enclosure was anticipated to produce a “miosis” function, or the constriction of light, based on thermal expansion properties of smart materials and programmatic structural arrangement. With no exposure to sunlight, the enclosure can reverse or contract and a “mydriasis” or dilation function, will occur allowing for indirect light to penetrate into interior spaces based on the orientation and the material’s ability to recoil with lack of heat input (Figure 08).


 Figure 09, Eye Adaptation, National Eye Institute. (Miosis -Left, Mydriasis - Right).

Functionally, the shading system’s passive characteristics were aimed to minimize heat gain, glare, and undesired reflection of sunlight in and on an enclosure while optimizing visual contact to the exterior. Physiologically, the interior space is intended to be a place to reside, whether one is working, studying, reading or praying-- a place where time is expressed by the movement of the sun with a direct expression of life based on the diurnal and seasonal display of light and shadow. To evaluate the design, the Solar Heat Gain Coefficient (SHGC) scale, which provides a value of measure based on the systems material and design characteristics, was used to qualify the design. The optimization of a low SHGC is constantly contrasted by the amount of visual connection from interior to exterior and vice versa, a high SHGC allows maximum visual contact but minimal thermal properties. The research and prototype development aimed at adapting these performance values to maximize functional properties and the resultant system is proposed to have the following values: R-Value between 4.00 to 5.00; U-Value between 0.20 to 0.25, and SHGC of 0.25 to 0.30. These estimated values are comparable to a variety of exterior shading systems, including, exterior vertical fins, canvas awnings, roof overhangs, and trees, to name just a few.

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With every prototype an installation is necessary to evaluate the design and for the compliant shading enclosure, the east and west building facades in a hot and arid climate was the intended platform. The alternating exposure from intense direct light to indirect diffused light and finally to no light from east to west is a known phenomenon, which allows for design creativity in consort with the sun’s energy as a power source. The north building facade was not used for this research given our location in the northern hemisphere and the minimal direct light penetration throughout the year. In the same manner, the south building facade was not used due to the existing shading techniques developed for passive solar shading.

mechanism and attached fabric closed, and back open in a cyclical manner.




Figure 11, SEEDpod Compliant Shading installation: interior view from kitchen/eating module.

The compliant shading system promotes diversity in adaptable surfaces with the capabilities of regulating solar exposure throughout a single day and throughout an entire year with no user input and no maintenance. More testing and fine-tuning of the bi-metal actuators metallurgical properties will allow future prototypes to adapt to variable climatic regions and would allow for the incorporation into buildings in extreme arid lands to moderate and even mild regions. This future research agenda is an important component of sustainable practice, which assists in maintaining and regulating levels of human comfort in the built environment. Figure 10, Open to Closed Conditions.




The precise measurement of the R-Value, UValue, SHGC values have yet to be conducted with regulatory testing procedures and proper data allocation at this time but it is the intent to conduct these guideline tests for future prototypes. Furthermore, these figures can be altered with other known relationships, such as: triple pane windows, Low-E glazing applications, and ventilation systems for windows.

4. CONCLUSION The final prototype window system was incorporated into the SEEDpod dwelling was a 6' by 6' double glazed window panel that was located on the East facade of the structure, challenging the question of how the suns rays can be responsive to the enclosure from the early morning to midday. The glass panel incorporated 66 actuators of thermal expansion bi-metal coils, a movable frame established by a spring-like bi-stable mechanism with 54 apertures, and a secondary system of polyester fabric to shade the window. By placing the bi-metal coils within a sealed glass enclosure, an elevated change of temperature could be obtained due to the greenhouse effect, increasing the range of rotational motion and force exerted by the coiled actuator, which in turn could snap the bi-stable

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5. ACKNOWLEDGEMENTS Research, prototyping, and construction of the SEEDpod dwelling unit was based on work initially proposed for the UASD grant proposal submitted to the United States Department of Energy: completed by Larry Medlin, Joseph Simmons, Dale Clifford, and Jason Vollen, 2007. Grants from the University of Arizona College of Architecture and AzRISE provided significant project support through the duration of the project and beyond. Principle Investigators include: Christopher Domin, Larry Medlin, Álvaro Malo, Joseph Simmons and Matt Gindlesparger The core student team included both graduate and undergraduate members: Eddie Hall, Anton Toth, Peter Secan, Sherwood Wang and Brent Vander Werf. Tom Reiner at Buro Happold: Los Angeles provided structural engineering consultation and analysis.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

6. REFERENCES [1] [2] [3] [4]

[5]

[6] [7] [8]

Domin, C. Medlin, L. 2010. Homeostasis and Perpetual Change. Eco Architecture III. Wessex: WIT Press. Clifford, D. Vollen, J. 2009. Smart and Sustainable rd Built Environments. SASBE 3 CIB International Conference. Healthy Buildings, Healthy People: A Vision for the st 21 Century: EPA 402-K-01-003, October 2001. Principal Investigators Larry Medlin and Christopher Domin worked with Brent Vander Werf (graduate student at CALA) and his thesis committee: Alvaro Malo, Larry Medlin, Nancy Odegaard on the development, prototyping, and integration of the selfregulating skin system into the SEEDpod prototype dwelling. Medlin, R.L. 1985. Portable/Adaptable Membrane rd Structures. 3 International Symposium on Widespan Structures, Vol. 2, University of Stuttgart, Sec. 3.4: 41-48 Howell, Larry L., Compliant Mechanisms / Larry L. Howell - New York ; Chichester [England] : Wiley, c2001. Thermostat Metals Designer’s Guide. Texas Instruments, 1991. “EngineeredMaterialSolutions.” .

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Development of the Solar Cooling in the Mediterranean Area Francesco PATANIA1, Antonio GAGLIANO1, Francesco NOCERA1, Aldo GALESI1, 1

Energy and Environmental Division of DIIM, University of Catania, Catania, Italy

ABSTRACT: Cooling demand is rapidly increasing in many parts of the world, especially in moderate climates, such as in most EU member states. This results in a dramatic increase in electricity demand on summer season, which causes an unwanted use up of fossil and furthermore the instability of electricity grids. Demand Reduction is, therefore, the key to ensure the sustainability of energy supply, making existing buildings more efficient and constructing new buildings with optimum energy demands As many cooling applications, such as air conditioning, have a high coincidence with the availability of solar irradiation, the combination of solar thermal and cooling obviously has a high potential to reduce the electricity consumption of conventional air conditioning. Using solar thermal energy is an interesting option for heat-driven air conditioning: e.g. desiccant cooling, absorption chillers. In this paper, the autonomous operations both of a solar desiccant cooling plant and absorption chillers powered by direct-flow vacuum-tube collectors are investigated. The overall cooling efficiency of the two systems is evaluated using simulation for humid and moderately humid climates, the overall cooling efficiency is studied and finally the overall efficiency of the collectors is calculated for the studied cases. It is found out that the proposed system can lead to significant electricity consumption reductions. Keywords: [cooling energy, desiccant cooling: solar collectors]

1. INTRODUCTION The growth of cooling loads in modern buildings with low thermal inertia causes the increases of the peak electricity demand during the day. Solar energy for cooling purposes could make a significant contribution to lowering the energy consumption. The main argument for the applicability of solar energy is that cooling loads and solar availability are approximately in phase Recent advancements in desiccant dehumidification and evaporative cooling technologies signal the incipience of new HVAC products that further enhance the technological portfolio of distributed energy resources. Through different system configuration and integration, such systems can facilitate effective temperature and humidity control for buildings with the most stringent ventilation requirements in a vast domain of climatic conditions The so-called Desiccant Cooling Systems (DCS) combine sorptive dehumidification, heat recovery, evaporation and heating to create a cooling process which can offer energy savings compared to conventional air conditioning systems. DCS takes air outside or inside the building, dehumidifies it with a solid or liquid desiccant, cools it by heat exchange and then cools it to the desired state The dehumidification achieved depends on the inlet conditions of the entering air, on the velocities in the process, the regeneration section and the regeneration temperature and humidity.

Furthermore, the rotation speed influences the performance significantly: faster rotation leads to incomplete regeneration and dehumidification, lower rotation speeds lead to a lower dehumidification, as the maximum possible water content in the adsorbent is reached some time before entering the regeneration section. The desiccant must be regenerated by heat. This can be achieved with extra heat produced by existing processes, i.e. heat coming from CHP process (Combined Heating and Power) - thus resulting in a CCHP system (Combined Cooling, Heating and Power) - or solar energy coming from solar air collectors or liquid collectors. The use of the solar source in summer justifies the economic investment for the installation of the solar collectors which, in winter time, reduce the energy demand of the conventional heating system with a further reduction of dioxide release. Implementation of such cooling technologies can also lead to significant downsizing of on-site power generators.

2. DESCRIPTION OF PROPOSED SYSTEM Several studies show that desiccant cooling system have a limited dehumidification potential for given features of the desiccant rotor, the regeneration temperature, the supply air flow rates and so on. Therefore an auxiliary cooling power for dehumidification is required to fulfil the desired supply air conditions. [1]

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In fact, if the humidity ratio and/or temperature set point of supply air is not reached, further decrease of dehumidification and temperature can be achieved by means auxiliary cooling coil. The objective of this paper is to study the thermodynamic efficiency of an hybrid desiccant cooling system applied in the context of a hot and humid region located in the South of Italy. As depicted in Figure 1, the system consists of an Air Handling Unit (AHU) equipped with an hybrid desiccant cooling that integrates desiccant, evaporative and conventional cooling technologies The thermodynamic transformation of the air are shown below:  The ambient air, point 1, flows through a rotary desiccant wheel (DES) and becomes hot and dry, point 2.  This air then flows through a sensible heat exchanger (HX),to be cooled down, point 3.  The dry, cooler air then flows through a cooling coil (CC) to be cooled toward the request

temperature and is delivered to the house, point 4 (I).  The exhaust air from the house, point 5, flows through the humidifier (HU) to be cooled to point 6, and then flows through the sensible heat exchanger (HX) to exchange heat with processed air.  The exhaust air from the heat exchanger, point 7, flows through the heating coil (HC) to elevate its temperature to point 8. This hot exhaust air is used to regenerate the desiccant dehumidifier. The desiccant dehumidifier is regenerated with solar energy from vacuum tube collectors. An heat storage tank balances the heat produced by the solar system and the heat supplied to the heating coil (HC) in order to reach the regeneration temperatures of 70°C at the least in the inlet of the desiccant rotor.

Figure 1: DCS System configuration

Figure 2: Daily Temperatures and Solar Irradiation.

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Humidity Ratio

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Dry Bulb Temperature

Figure 3: Thermodynamic transformations on the psychometric chart

  Figure 4: Thermal Storage temperatures

3. OPERATIVE CONDITION The Authors show the results achieved for the summer climatic conditions of a town located in Southern Italy (Catania) and for three value of supply air demand of 1500,0, 2.000,0 and 3.000,0 m3/h, considering a time of occupancy between 9 a.m. and 6 p.m. The indoor space load is characterized by the following design supply - and return-air conditions: - Supply air (S.A.) at a temperature of 20°C and humidity ratio of 9.8 g/kg of dry air - Return air (R.A.) at a temperature of 26°C and humidity ratio of 12 g/kg of dry air. The sensible heat factor, SHF, of the indoor space load is considered equal 0.7.

This approach is important for the assessment and performance comparison of the desiccant cooling with other conventional systems. The values of outside temperature Te and Solar Irradiation used in the simulations are referred to the th 15 July. The selected desiccant wheel is equally split (50/50) between the process and regeneration air streams and rotates at an optimum or near-optimum speed (18 to 24 RPH). The process-air velocity is maintained between 2.8 m/s and 3.0 m/s at standard conditions (15°C and 101.039 kPa). The desiccant is assumed to be regenerated at 70°C, representing the regeneration air temperature downstream of the Heating Coil (Figure 1).

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To evaluate the performance of this commercially available unit, the manufacturer's performance software has been used [2] The heat recovery efficiency (0.85) and the  humidifier efficiency (0,90) are assumed constant. Figure 3 shows the thermodynamic transformations of the air in the AHU on the psychometric chart considering for the air at the state 1 ( outside air): T=30,5 °C and x =14 g/kg; It can be noted that no additional dehumidification is generally required to reach the desired supply humidity ratio, due to the moderate humidity ratio of the outside air ( about 14 g/kg). The expected supply temperature of 20°C is reached by means of the auxiliary Cooling Coil (CC). In this case, for the post-cooling the temperature of 12°C is enough and consequentially the vapour compression chiller COP increases. As shown, it is not necessary the post-heat and the dehumidifying cycle will be much more efficient from the energy point of view

4. SYSTEM ANALYSIS For the three values of supply air demand analysed was calculated the minimum area of solar collectors needed to supply the energy to the regenerative heat exchanger (HC). In this way, the heat produced by the collector field is stored and available to the HC when its temperature is adequate. For the storage tank was considered a capacity of 25 litres per square meter of solar collector 4.1. Energy Balance The temperature of heat storage has been calculated by means its Energy Balance m  C H 2O  Ti 1  Ti  

Δτ

 (Qcol  Qd  Q R ) (1)

where: m = mass storage [kg ]; C = specific heat [ kJ/kg°C] ; Ti = storage temperature at time “i” [K]; Ti+1 = storage temperature at time “i+1” [K] Qcol = solar collector heat flux [kW] ; Qd = storage thermal loss [kW] ; QR = regeneration energy [kW] ; Q R  m Ra  Cpa  Tu  Ti 

 

Table 1: Technical parameters of the DCS

mSa (m3/h)

1500

2000

3000

mRa (m /h)

750

1000

1500

Whell Diameter QR (kW)

500

770

965

7,10

10,2

15,4

QDEC

7,40

9,60

14,40

QCC(kW)

3,02

4,02

6.03

15

22

32

400

550

800

3

Area of Solar 2 collector (m ) Heat storage capacity(liter)

The results obtained show that it may be possible to reduce the regeneration air flow without a significant reduction in the dehumidification efficiency, enabling desiccant cooling systems to run with high COPs The figure 4 shows the temperature variations in the accumulation for the three scenarios examined

 

It can be observed that the temperature of the thermal storage is always higher than the expected regeneration temperature during the operating time. Moreover, there is a nearly constant relationship between the regeneration heat provided through solar collectors and the air flow of 1 kW every 200 m3/h of supply air, resulting in a ratio of 1m2 of solar collectors every 200 m3/h of supply air 4.2. Performances indicator of DCS

(2)

mRa = mass rate of air regeneration [kg/s ]; Cpa = specific heat of air [ kJ/kg°C] Tu =outlet temperature from heating coil (HC); Ti = inlet temperature into heating coil (HC)

On the basis of the previous results the following energy performance indicators have been calculated[3]. Q (4) SFDEC  1  CC Q DEC

 

Q HC I Q COPth  DEC QHC

 

PE 

Qcol = Qsun* ηcol Qsun = heat rate from sun to the solar collector, [kW] The performances of the evacuated heat-pipe solar collectors have been calculated utilising the following equation [2]: ηcoll = 0.82 - 2.19 (Tm-Ta)/ G

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where Tm is the mean collector temperature, equal to (Toutlet+Tinlet)/2 , Ta is the ambient air temperature and G is the solar 2 irradiance (W/m ). The main technical parameters of the system and the contributions of the cooling power produced by the desiccant cycle (QDEC) and the auxiliary cooling power (QCC) are summarized in the following table for the considered operative conditions.

(3)

HVAC - EQUIPMENT AND REGULATION (COMPLEMENTARY TO DESIGN)

 sh 

Qel Qre  heating  el  fossil

(5) (6) (7)

Q AHU (8) PE The SFDEC is the fraction covered by the desiccant cycle to the total cooling energy delivered PER 

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

by the AHU (QAHU) and has been calculated by equation (4). The solar heat efficiency (sh) describes the quantity of incident irradiation what is usefully utilized in the system and has been calculated by eq. (5) The thermal COPth of the desiccant AHU indicates the ratio between the cooling energy produced by the desiccant cycle and the regeneration heat delivered by the solar heating coil HC and has been calculated by eq. (6) The Primary Energy (PE) consumption has been calculated by eq. (7) The Primary Energy Ratio PER which is a benchmark for energy efficiency has been calculated by the formula (8) In evaluating the energy for the fan have been considered the pressure drop across the wheel ranges from 140 Pa to 215 Pa for the process side and from 220 to 363 Pa for the regeneration side. Table 2 shows the values calculated for the above parameter Table 2: Calculated Energy performance Indicator .

Supply air demand SFDEC

1500

2000

3

(m /h)  0.59

3

3000 3

(m /h)  (m /h)  0.58 0.58

sh

0.64

0.63

0.63

COPth

1.04

0.94

0.93

PER

1.94

2.03

2.03

It is possible to notice that:  the system is able to supply about 60% of the total cooling required for the transformation of moist air  the efficiency of solar collectors, under the operational conditions, take more than satisfactory values remaining above 60%.  the primary energy ratio indicates a production of 2.0 kWhcold / kWhPE primary energy supplied.  desiccant systems achieve a primary energy coefficient of performance (COP) between 0.94 and 1.0, that is a real good result. The results confirm that the solar energy is an excellent, practical heat source for desiccant regeneration

5. COMPARISON SYSTEM

WITH

CONVENTIONAL

The energy performance of the proposed system, have been compared with a traditional AHU where the cooling energy is supplied by means a traditional Vapour Compression Refrigeration (VCR) system or by means an Absorption Refrigerator (AR). The energy needed for the cooling coil for a traditional AHU, in the case of volumetric air flow of 3000 m3/h, is about 27.20 kW that is significantly higher than the one required for the DCS system. For the absorption refrigerator the heat needed for the generator could be supplied entirely by solar

panels. This condition would required about 80 m2 of solar panels to fully supply the energy needed for the generator during the operating time. To allow proper comparison between different cooling systems for the case of absorption chiller, thermal energy needed for the generator is supplied by solar collectors for a rate corresponding to an area of 32 m2, that is the same area utilised for the DCS system. The remaining rate of thermal energy is supplied by an auxiliary source In addition the following assumptions have been utilised to compare the three cooling systems. : - the absorption chiller is single stage with efficiency equal to 0.7. - the energy required for the post-heating is provided in all cases by the solar panels. - since the desiccant wheel and the additional coils cause higher pressure losses than in a conventional AHU, different electricity consumption for ventilation have considered for the two systems. The calculated electricity consumption for ventilation of the reference AHU has considered to 47% of the one of the desiccant cooling AHU [1] In the calculation of the primary energy consumption related to the cooling energy it also was assumed the same chiller performances of that one used in the DEC system. In order to estimate the energy saving obtained in comparison to a reference AHU, the primary Energy consumption of all systems have been calculated with the general formula (8) taking in account for the absorption chiller unit also the necessary heating energy delivered from a gas boiler to achieve the necessary energy for the generator. Table 3 shows the values calculated for the energy performance indicators. The overall COPsAR of the solar absorption refrigerator has been calculated such as the product of the efficiency of the solar collector (ηs) and the COPAR of the absorption refrigerator given by equation (9). COPsAR = ηs COPAR

 

(9)

Table 3: Energy performance comparison

Cooling System sh

DCS

VCR

0.63

0.54

COPth

0.93

0.35

PER

2.03

0.86

AR

0.81

The primary energy ratio for the desiccant unit, PER is 2.03 kWhcold/kWhPE, whereas the one for the vapour compression system amounts to 0.81 kWhcold/kWhPE and the one for the absorption chiller is 0.86 kWhcold/kWhPE In other terms, the primary energy saving of the desiccant system is more than 50% for the considered operational conditions. The following table shows the obtainable amount of economic and emission savings for a period of functioning of 800 hours per years.

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7. REFERENCES Table 4: Economic and Emission savings

Supply air demand Economic Saving [euro]

1500 3 (m /h) 

2000

3000

3 3 (m /h)  (m /h) 

343,30

475,00

712,50

986,70

1324,10

1986,20

 

Emission Saving [kgCO2 ]

 

So it is possible to affirm that desiccant cooling systems provide a significant energy-saving advantage over conventional systems.

6. CONCLUSION The results obtained for the calculated energy perfermorce confirm that the solar energy is an excellent, practical heat source for desiccant regeneration. Particularly in Mediterranean Area characterised by mean summer temperature of 30°C and absolute humidity of 14 g/kg, no additional dehumidification device are necessary. For the analysed operational conditions it is possible to notice significant energy saving, more than 50%, respect both to conventional system and absorption refrigerator. The significant energy-saving advantage over conventional systems indicates the possibilities of a large use of desiccant HVAC systems. The replacement of compressor cooling systems by solar driven desiccant cooling systems or a combination of both could offers an important contribution to environmental protection. In addition the DEC reduces energy operating costs significantly where peak electric utility demand charges are high, moreover these system could contribute to reduce grid congestion, energy price volatility, and emissions. Nevertheless the initial investment for a DCS is higher than conventional system and it is a real limit for a large diffusion of the solar cooling technologies In our point of view, the following conditions are needed: efficient integration techniques plus an utility incentive grant could eliminate any first-cost penalty for desiccant equipment.

 

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[1] www.cibse.org [2] http://www.osti.gov/bridge [3] M. Beccali, P. Finocchiaro, M. Luna, B. Nocke (2008) Proc. Eurosun 2008 - Lisbona [4] A. Jalalzadeh-Azar, S. Slayzak, R. Judkoff, T. Schaffhauser &I R. De Blasio (2005) International Journal of Distributed Energv Resources. 1614 [5] V. C. Mei and F. C. Chen Z. Lavan R. K. Collier, Jr. G. MecklerAn Assessment of Desiccant Cooling and Dehumidification Technology Prepared by the Oak Ridge National Laboratory [6] E. Wurtz, C. Maalouf, L. Mora, F. (2005)Allard Ninth International Ibpsa Conference Montréal, Canada , 15-18,

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Methodological development of seasonal cooling energy needs by introducing ground-cooling systems Marta OLIVEIRA PANÃO, Helder GONÇALVES LNEG, National Laboratory of Energy and Geology, Lisboa, Portugal ABSTRACT: In past years, building professionals increased their interest on passive systems as sustainable solutions to reduce energy needs. This has been driven by the building certification program and new Portuguese building thermal code enacted in 2006. For residential and small office buildings, the methodology adopted is a seasonal quasi-stationary approach for calculating cooling energy following EN ISO 13790:2007. However, this method lacks specific recommendations for accounting passive cooling systems, namely groundcooling systems. In this paper, the ground-heat exchanger contribution is included in the energy needs method. This development is sustained by measurements obtained in the ground-heat exchanger running on Solar XXI office building at LNEG campus, complemented by simplified and Fourier theoretical formulations. The horizontal ground-heat exchanger at Solar XXI is constituted by 32 concrete ducts, with a 30 cm diameter and buried 4.6 m deep. The air entrance is made from a feeding well about 15 m away from the building and its functioning during summer warm days supplies cool air for room offices. Keywords: energy needs, ground-cooling, ground-heat exchanger, ventilation, passive building

1. INTRODUCTION In European Union, building sector is the largest energy user and carbon dioxide (CO2) emitter, where 40% of the energy and CO2 emissions derive from energy use in residential and commercial buildings [1]. To overcome this situation, in 2000, the European Commission identified the need to introduce specific measures in the building sector, namely with the Energy Performance of Building th Directive (EPBD) published on December, 16 th 2002 [2] and followed by its recast on June 18 2010 [1]. This Directive proposes, among other issues, the adoption of common methodologies for calculating energy consumption and opens the way to net zero energy buildings in 2020 [1]. According to the EPBD, Portugal prepares the evaluation of national requirements for energy performance of new buildings until 2011, which is an excellent opportunity to devise a national strategy making way to very low energy buildings. Summer Mediterranean climate causes a great thermal stress in buildings, nevertheless, traditional and passive architecture shows reduced cooling energy demanding examples, so that HVAC systems are not required [3]. In the latest years, architects and building professionals increased their interest on passive systems as sustainable solutions to reduce energy needs. However, the method for calculating cooling energy needs incorporated into Portuguese thermal building code [4], RCCTE, which is based on the method developed by Dijk and Spiekman [5] and gave rise to EN ISO 13790 [6], lacks specific recommendations for accounting passive cooling strategies, namely ground-cooling. This fact penalizes passive buildings, especially residential and small services, because when

compared with standard buildings similar cooling energy needs are estimated. This paper studies a simplified method to account for the additional heat transfer by ventilation with supply of air from a ground-heat exchanger (GHE), therefore cooler than external air for the most part of the day during summer. Calculation of cooling energy needs follows EN ISO 13790 and the groundto-air heat exchanger approach in EN 15241 [7], which proposes a methodology to account for preheating air supply for commercial buildings, instead of cooling air supply.

2. EN ISO 13790: SUMMER 2.1. Cooling energy needs The method developed by Dijk et al. [8] is also described in detail in EN ISO 13790 and consists of a numerical estimative of the physical quantities of heat transfer (QC,ht) and heat sources (QC,gn), different from a merely comparison between gains and losses. The heat transferred by ventilation (including infiltration) and transmission (conduction, convection and longwave radiation) directly depends on the inside-to-outside air temperature difference and is part of the first term. The exchange of energy which does not fit in the first term constitutes the heat sources, e.g. shortwave radiative gains, additional sky longwave radiative exchange and internal gains. There are two formulations of the same numerical method to calculate cooling energy needs (QC,nd), one uses the loss utilization factor (C,ls) and the other uses the gain utilization factor (C,gn). In the gain utilization factor formulation, the one adopted in RCCTE, cooling energy needs are given by

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female secondary school students in Tehran and to investigate the thermal comfort and indoor air quality in the classrooms.

2. CLIMATE OF IRAN AND THE CITY OF TEHRAN Iran is a country located in the Middle East and covers over 1,648,195 km², with a land area of 1,531,595 km² and a water area of 116,600km². It extends between latitudes 25°N and 40°N and longitude 44°E and 63° E. The city of Tehran is located on the southern border of the Alborz Mountain. Tehran has hot-dry summers and cold winters. The climate of Tehran is generally characterised by its geographic location and it is usually cooler on the north side compared to the southern part. The annual precipitation is low and the average rainfall on the plain is about 218 mm and the maximum rainfall is about 50 mm in November [5]. Figure 2 shows the average annual temperature range in Tehran.

Table 1: Summary of samples

Classroom N (north facing) S (south facing) Total

Number taking part in survey 23 22 45

3.1. Objective Physical Measurement The school is located in south-west of Tehran and has four storeys. The measurements assessed thermal condition of the classrooms during lesson hours in the warm months of April and May for three weeks, 26th April 2010 to 15th May 2010, on the top floor. Thermal comfort variables such as indoor air temperature and relative humidity were measured by HOBO loggers. HOBOs were located at a height of 2.0 metres above the floor, on top of the blackboard. They were collecting indoor temperature and relative humidity with a logging interval of 15 minutes. Daily local weather data were also extracted from local weather station reports. Table 2 presents the means of indoor temperature and relative humidity as well as their standard deviations for the two classrooms. Measurement results were divided in to weekdays (W), representing 17 days, and weekends (WE), representing 3 days. Table 2: Mean indoor temperature, mean relative humidity and standard deviations in two classrooms for weekdays (W) and weekends (WE).

Classroom Figure 2: Temperature range in Tehran [6]

Moreover, relative humidity reaches 66% in December and decreases to 27% in July and also the average dry bulb temperature is 5°C in January and 32°C in July [6].

3. METHODS AND DATA COLLECTION In order to achieve the study‟s aims, a series of field studies, that used survey questionnaires and field measurements, were conducted in a four storey female secondary school for three weeks during spring. The measurements assessed thermal conditions during lesson hours in the warm months of April and May. Overall, 45 questionnaires were completed in two classrooms on the 4th May 2010 by the students. Thermal comfort variables were measured for a three week period, which included the survey date, by HOBO data loggers. HOBO loggers tracked temperature and relative humidity inside two classrooms. Details of the classrooms occupants are given in Table 1. A comparative analysis has been performed on the result of the field studies from the classrooms, which were located on the north (N) and south (S) facing sides of the school on the top floor. Later, the results from the field measurement were compared with the results of the questionnaire survey.

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N S

Mean S.D Mean S.D

Indoor temperature (°C) W WE 24.9 24.1 1.3 0.5 25.0 24.2 1.5 0.5

Indoor relative humidity% W WE 34.0 31.7 6.3 5.8 29.3 27.8 7 6.2

From Table 2 it can be seen that the mean indoor temperature, mean relative humidity and their standard deviations during the weekdays are higher than at weekends. Generally, the standard deviation of indoor air temperature is smaller than the standard deviation of indoor relative humidity. During the weekends the school does not have any occupants, which results in lower humidity levels. However, the mean temperature of the classroom rises during the weekdays, possibly due to increasing activity levels in the classrooms. Moreover, although the school has an air conditioning system, it is hardly used during the warm seasons in order to keep energy bills low. During the three week assessment, the air conditioning system was kept off and classrooms were naturally ventilated, which resulted in a higher temperature range during the weekdays. 3.2. Questionnaire Assessment of thermal comfort in the classrooms was based on a questionnaire survey. A total number of 45 students from classroom N and classroom S th participated in the survey at noon on the 4 May 2010. They answered questions on their perception of

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4. CASE-STUDY 4.1. Solar XXI building Solar XXI office building [9], at LNEG campus (Fig. 1), has a GHE constituted by 32 concrete ducts (Fig. 2), 30 cm in diameter and buried 4.6 m deep. The air entrance is made from a feeding well about 15 m away from the building (Fig. 3) and the system is projected to function during summer warm days supplying cool air to the room offices facing south. Each office room in the south part of the building has two ducts supplying an air flow rate that corresponds to 8.7 ACH.

annual measurements for ground temperature at the corresponding depth (Table 1). Annual average and amplitude swing are taken from a typical reference year of Lisbon climate and are, respectively, 16.3 and 8.5ºC. Table 1: Ground characteristics.

Ground-cooling system Amplitude correction factor, am

0.34

Ground material factor, gm

1

Curve shift, m (h)

0

4.3. Ducts characteristic constant For one duct of the GHE of Solar XXI building (see characteristics in Table 2), the estimated airduct heat transferred is 64.9 W/K and the convective inflow is 65.7 W/K, which results on =0.987 and a GHE efficiency of A=0.63. Table 2: Duct physical characteristics and air flow rate. Figure 1: South façade of Solar XXI building. Architects: Pedro Cabrito and Isabel Diniz.

Ground-cooling system Inside surface coefficient

4.7 W/(m2K)

Concrete conductivity

2.0 W/(m2K)

U-value

2 4.6 W/(m K)

Total surface area Air-flow rate

14.1 m

2

3

200 m /h

The complete analytical solution for the heat diffusion of a cylindrical air/soil heat-exchanger proposed by Hollmuller [10], was used to compute, on an hourly basis, the room supply air from the GHE - ghe - for the summer period of Lisbon’s climate. The theoretical dashed line (Fig. 4) of that model can be approximated by

Figure 2: Semi-buried floor plan: ground-heat exchanger ducts.

Figure 3: Building cross-section: ground-heat exchanger.

4.2. Ground temperature The amplitude correction factor at 4.6 m deep (d) is obtained from the empirical correlation [7]: with c1=3.35x10-4, c2=1.382x10-2 and c3=1.993x10-1. The other parameters were set according to the

Figure 4: Ground-cooling efficiency from a theoretical approach (dotted line), Fourier analysis (dashed line) and fitted to measurements (solid line).

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It is noteworthy, that the duct constant physically estimated for this system - the ground-heat exchanger efficiency, A=0.63 - is above the calculated by a detailed hourly method based on Fourier analysis of the external air temperature (A=0.53), which takes also into account the soilduct-air heat transferred. Furthermore, the ground-cooling system was monitored during a summer week keeping the fan continuously on. During that period the office room was unoccupied and the external shading devices were kept semi-opened. The empirical correlation found for the experimental data (Fig. 4) establishes a duct characteristic constant of 0.83. It is noteworthy, that an efficiency of 0.83 requires that ratio between Htr and Hcv be =1.7, therefore the air-duct heat transmission should be higher than the estimated or the convective inflow be lower. For example, ducts tightness could cause differences between fan and duct flow rate. Future measurements will take into account the above discussed issues to infer about the GHE efficiency.

Mechanical ventilation supplying air from GHE for limited hours of use, infiltrations of 1 ACH for the remaining period. In this analysis, cooling energy needs are only influenced by the overall ventilation heat transfer coefficient, Hve, calculated from the air flow rate and the adjustment factor, bve, for each type of ventilation type according to the hours of use. Table 4 shows the average values for external-toground and internal-to-external temperature differences, which are the parameters used to obtain bve. Those adjustment factors (Table 5) are calculated assuming that int-set (different from ’int-set) is 3.44, the average temperature difference for 24h, and a GHE efficiency equal to 0.63. 

Table 4: Average external-to-ground and internal-toexternal temperature differences, calculated for Lisbon climate, from June to September, for different periods.

hours of use

’ext-grd (ºC)

’int-ext (ºC)

0-24 h

4.06

3.44

9-18 h

8.50

-1.00

22-7 h

-0.14

7.63

9-13 h

5.75

1.75

5. COOLING ENERGY NEEDS

14-18 h

10.81

-3.32

The test case for cooling energy needs calculations is a double office room, located in the first floor of Solar XXI building, with the characteristics of Table 3.

9-11 h

3.69

3.80

11-13 h

7.80

-0.31

13-15h

10.71

-3.22

15-17 h

11.13

-3.64

17-19 h

8.97

-1.48

Table 3

Thermal descriptive parameters for office room.

Office room Floor area (m2)

30.6

Volume (m3) Overall transmission heat transfer coefficient (W/K) South effective collecting area (m2) Horizontal effective 2 collecting area (m ) Thermal inertia, aC

91.8

Fans total air-flow rate (ACH)

53.8

Hve [W/K]

bve

1.66

Hours of use

EXT

0.13

Infiltrations

1

-

30.6

-

0-24h

1

1.74

266.7

464.9

9-18 h

-0.29

2.56

-9.9

274.8

22-7 h

2.22

0.97

240.9

116.6

9-13 h

0.51

2.05

48.1

116.7

14-18 h

-0.97

2.98

-17.4

157.9

9-11 h

1.10

1.68

52.6

65.3

11-13 h

-0.09

2.43

26.0

82.0

13-15 h

-0.94

2.96

7.2

93.9

15-17 h

-1.06

3.04

4.5

95.6

17-19 h

-0.43

2.64

18.5

86.8

2.6 8.7

Calculations are performed for Lisbon climate, 38.8ºN, 9.1ºW, for a four-month period (June to September), with an average external air temperature of 21.6ºC and an integrated global 2 horizontal solar radiation of 792 kWh/m . The setpoint temperature is set to 25ºC. The cooling energy needs are estimated for the following ventilation strategies:  No mechanical ventilation, infiltrations of 3 1 ACH (qve,inf = 91.8 m /h);  Continuous mechanical ventilation 3 (qve,mech = 800 m /h) supplying air from exterior (EXT);  Continuous mechanical ventilation 3 (qve,mech = 800 m /h) supplying air from GHE;  Mechanical ventilation supplying air from exterior for limited hours of use, infiltrations of 1 ACH for the remaining period;

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Table 5: Ventilation thermal parameters for different hours of use of mechanical ventilation with supply air from exterior (EXT) and ground-heat exchanger (GHE).

HVAC - EQUIPMENT AND REGULATION (COMPLEMENTARY TO DESIGN)

GHE

EXT

GHE

From the above overall ventilation heat transfer coefficients for each solution, it can be concluded that air supplied by GHE is always the best solution, with the exception of night-time ventilation (22-7 h) where bve and, therefore Hve, are higher compared with GHE use. This study underlines, therefore, that daytime ventilation is not recommended for warm summer periods because it increases thermal loads.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

On the other hand, GHE use is a good solution to ventilate during daytime hours. It is also relevant that the two-hours period where for most efficient GHE use is 15-17 h characterized by an exterior-to-ground temperature difference of 11.13ºC, which results in the maximum value for be of 3.04. In respect to the selection of preferential period to use GHE, morning or afternoon, the results show that bve and Hve are higher for 14-18h in respect to 913h. The results obtained for cooling energy needs of the tested office room (Fig. 4) show that mechanical ventilation with external air supply reduces office cooling energy needs if it occurs during nocturnal and morning periods. When the air is supplied by GHE, however, mechanical ventilation can also be promoted during afternoon hours, characterized by air temperatures above the set-point temperature, so that the average external-to-internal air temperature difference is above 3ºC (Table 4, 13-15h, 15-17h).

6. CONCLUSION This paper proposes a simplified formulation to include ground-cooling systems, i.e. mechanical ventilation where air is supplied comes by a groundheat exchanger (GHE). For the ground-cooling system of Solar XXI building, the measured GHE efficiency was compared with two theoretical formulations – physically simplified [7] and Fourier method [10] – having been obtained lower estimatives compared with measurements. The adjustment factor, bve, already established in EN 15241 for air preheating with GHE is here adapted for cooling ventilation. This factor depends on ducts characteristic constant, A, or GHE efficiency and average external-to-ground temperature difference for mechanical ventilation hours of use. The method proposed can be easily implemented in both seasonal and monthly methods, as well as in the Portuguese thermal code (RCCTE). Future studies should address the ground-heat exchanger efficiency, as well as climate characterization in terms of period’s average air temperature, in order to enable extrapolating the method for multiple cases.

7. ACKNOWLEDGEMENTS Solar XXI building project and construction was funded by European Union, FEDER, and Portuguese Ministry of Economy, Program Prime.

Figure 5: Cooling energy needs for mechanical ventilation with external air (EXT) and GHE (ground-heat exchanger) for different periods.

Table 5 shows also that the bve factor is generally above one whenever GHE is used, and it is largest when GHE use is restricted to the warmest day hours. For example, for a two-hours period, 15-17h, the exterior-to-ground average difference is 11.1ºC (Table 4). It is noteworthy that, compared with no 2 mechanical ventilation use (21.9 kWh/m ), cooling energy needs decrease by 43%, when air supplied by GHE is fanned for the aforementioned two hours (Table 4). For the most part of the ventilation strategies with air supplied by GHE, cooling energy needs are 2 reduced to values below 15 kWh/m . The possibility of GHE use during 9-daytime hours leads to cooling energy needs below 2 5 kWh/m . This fact leads to conclude that the ground-cooling system is an effective passive strategy toward very low energy buildings during summer season. In fact, Solar XXI does not have any active air conditioning system and 73% among users manifested that thermal environment is acceptable during summer [11].

8. REFERENCES [1] CEC. Energy Performance of Building Directive, Directive 2010/31/EU. Official Journal of the European. [2] CEC. Energy Performance of Building Directive, Directive 2002/91/EC. Official Journal of the European [3] H. Goncalves, M. Oliveira and A. Patricio. How did the solar houses perform in Portugal? In Proceedings of the 22nd National Passive Solar Conference, Vol.22:17-21, Washington DC, 2530 Apr 1997. [4] Decreto-Lei nr. 80/2006. Regulamento das Características do Comportamento Térmico dos Edifícios, RCCTE. Portugal; 2006 (in Portuguese). [5] D. van Dijk and M. Spiekman. Energy Performance of Buildings; Outline for Harmonised EP Procedures. Final report of EU SAVE ENPER project, Task B6. TNO Building and Construction Research, Delft (NL), June 29, 2004. [6] EN ISO 13790 Energy performance of buildings, calculation of energy use for space heating and cooling; 2007. [7] EN 15241 Ventilation for buildings, Calculations methods for energy losses due to ventilation and infiltration in commercial buildings; 2007.

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[8] D. van Dijk, M. Spiekman and P. de Wilde. A monthly method for calculating energy performance in the context of European building regulations. In Proceedings of the Ninth International IBPSA Conference, Building Simulation 2005. Montreal, Canada; 2005. [9] H. Goncalves. Solar XXI Towards Zero Energy, LNEG, Lisbon, Portugal; 2010. [10] P. Hollmuller. Analytical characterization of amplitude-dampening and phase-shifting in air/soil heat-exchangers. International Journal of Heat and Mass Transfer 2003;46:4303-4317. [11] Solar XXI Building, Case Study nr.12, Advanced Ventilation Strategies, Building Advent IEE Project.

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Building integrated micro- generation systems for cooling, heating, and dehumidification in hot and humid climate zones Thomas Spiegelhalter1 1

Florida International University, Architecture, Co-Director Environmental Technology Lab (ETL), Miami, FL, USA

ABSTRACT: Out-of-control peak loads, power outages, and billions of dollars losses are often faced in hot and humid seasons through extensive fossil-fuel based electrical operated building air-cooling systems, barely capable of meeting the rising energy demand. The resulting fossil energy use and CO2 emissions are expected to increase continuously. However, the fact that peak cooling demand are associated with high solar radiation offers an excellent opportunity to exploit the use of combinations of passive climate design mitigation strategies with building integrated micro-energy generation systems that can match heat-driven space cooling strategies. Those are of particular interest in urban areas where adverse outdoor conditions of high outdoor pollution and the urban heat island effect, encourage the use of air-conditioning with a direct negative impact on peak loads. Suitable energy efficient building integrated hybrid technology such as combined solar assisted cooling and heating, decoupled dehumidification and air supply systems can help alleviate the problem as it is already increasingly practiced in the US, Europe and Asia. This paper will assess from the architect’s point of view research results of US, European, and Asian innovative projects with solar micro-regeneration systems for combined production of electricity, heating and cooling for 5 to 2000 kW applications. Keywords: Hybrid technology, Micro Energy Generation, Solar Assisted Air-Water Space Conditioning Systems, Thermo-Active Mass, Dehumidification,

1. INTRODUCTION: BUILDING LOADS AND CLIMATE DESIGN Climate engineering as a planning discipline develops solutions for energy efficient buildings that can adapt to different situations in which form and function are synergized in a holistic way. Every building location has its own individual micro-climate with respect to orientation, solar radiation, temperature, humidity, wind, noise, and air pollution. For climate responsive design, it is important to ensure the highest possible comfort for building occupants with the lowest possible impact on the environment. Therefore buildings have to be seen as an active system of constantly shifting loads, external inputs such as changing temperature, solar gain, acoustics, and moisture moving into and out of the spaces. Looking at the building as a complex system requires analysis and modelling tools since there are indirect and direct processes going on all the time. (Fig.1)

2. CRITERIA 2.1. Reduce Loads and Resource Demand First with Passive Design Strategies over Active Systems To use passive natural systems over active mechanical systems wherever possible is the starting point for any energy efficient building design to carefully analyze the contextual annual building load based on meteorological data, occupancy activities with psychometric indoor conditions, and to conduct economic comparisons of selected solutions over the

  

Fig.1 Criteria Chart for Thermal Driven CoolingDehumidification Processes, Source: T.Spiegelhalter whole life cycle. Another priority is to only use onsite renewable to meet all energy needs, or combined with local and regional renewable to make up the

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difference (doing the above steps before will result in the need for much smaller space conditioning systems, making sustainable, carbon neutrality in design achievable).

and the CO2 neutrality in the energy supply. It is necessary when using electrical cooling to ensure to use renewable energy.

2.2. Careful Building Load Design is Mandatory to Avoid Mismatches

2.3. Solar hybrid system driven Air-Conditioning

Human comfort is based not just on temperature and relative humidity in Thermal Comfort Design, but also on radiant temperature (the apparent temperature of surfaces), air flow, metabolic rate, clothing and even controllability of systems. By removing the emphasis on radiant effects, dressing appropriately and having remote and individual control of systems, planners can effectively provide comfort in buildings and save significant primary energy. Mismatches in load design and thermal design must be early identified in the design process, because buildings operate in dynamic environments that have an important influence on mandatory thermal comfort standards (ISO 7733, ASHRAE 55-2004). Building performance and air quality problems may arise with concerns on increased humidity levels and condensation during the space conditioning process of thermal-load shifting systems. These mismatches can lead to poor architectural and mechanical design choices and limit the ability to properly assess some of the most promising technologies of solar cooling and heating with decoupled humidification and air supply systems for hot and humid climates. Cooling loads are often caused by undesiredable internal (People, equipment, lighting, etc.) and external heat sources (Solar radiation, conductivity, transmission losses, thermal bridges, infiltration, etc.). One successful solution for those mismatches among different heat-driven technologies (absorption, desiccant, adsorption, jet cycles) combined with different types of building micro generation integrated PV-Wind, Solar Thermal and Heat Recovery Systems (Fig. 2.), for shifting loads in changing climatic conditions, is decoupled cooling (or radiant cooling), with systems combining chilled ceilings or shear walls with AHU for airdehumidification and ventilation (CC+AHU). Radiant cooling with independent air dehumidification and ventilation can act as a complementary cooling and ventilation technology that has the potential to provide better thermal comfort, air quality (with lower air velocities), and significant energy consumption reductions than conventional all-air systems. For example in terms of energy savings planners should prefer to use water as a heat transfer medium, instead of air, since water will transfer 1000 times as much energy as air for the same temperature difference. So far, in hot and humid regions of the U.S., fears for the risk of condensation on ceiling the market penetration in the implementation of waterand air based systems. To address this challenge, indoor humidity behaviours associated with decoupled cooling in hot and humid climate have been successfully tested in Europe and parts of Asia. To date, most of the cooling in the U.S. is performed by electrical non-renewable energy with compressor type refrigeration plants and reversible heat pumps. The electrical energy required has an unfavourable effect on the primary energy balance of the building

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The one of the most promising applications for micro generation solar hybrid cooling is solar assisted air conditioning (Fig. 3). The most common technologies used in combination with solar heat driven systems are generally classified into: Closed systems: these are closed cycles of thermally driven

 

Fig.2 Building Integrated Micro Generation Systems chillers which provide chilled water, that is either used in air handling units to supply conditioned air (cooled, dehumidified), or that is distributed via a chilled water network to the designated rooms to operate decentralized room installations, e.g. fan coils. Market available machines for this purpose are absorption chillers (most common) and adsorption chillers (a few hundred machines worldwide, but of rising interest in solar assisted air conditioning); Open systems: these are open sorption cycles allowing complete air conditioning by supplying cooled and dehumidified air according to comfort conditions. The “refrigerant” is always water, since it is in direct contact. with the atmosphere. Most common systems are desiccant cooling systems using a rotating dehumidification wheel with solid sorbent.

 

2.4. Liquid Desiccant Cooling Systems New developments are desiccant cooling systems using a liquid Water/Lithium-Chloride solution as sorption material. This type of system shows several advantages such as higher air dehumidification at the same driving temperature range as solid desiccant cooling systems, and the possibility of high energy storage by storing the concentrated solution. This

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

technology is a promising future option for further increasing the exploitation of solar thermal systems. The produced cooling capacity can be similar stored like heat energy in water tanks, in thermo-active system or in heat sinks. Efficient storage such as cold water tanks (which are limited to 0º Celsius), and ice storage, where the latent heat of the ice formation is stored in addition to the sensible heat, succeeds the storage densities approximate 10-times higher as the cold water tank. Ice storage can help to optimize the systems efficiency in situations with high cooling requirements and severe fluctuating supplies and peak utility rates.

can be significantly reduced and operating efficiency improved (because the system is operating less of the time at partial loads).

 

3. THERMO-ACTIVE MASS RADIANT COOLING SYSTEMS Compared with air systems, hydronic radiant-cooling systems only use approximately half the horsepower and materials to move heating and cooling energy within a building. Radiant-cooling systems have been used in Europe for decades and they are starting now to be examined and installed in the US. Low-flow injection-pumping systems can help make radiantcooling systems even more efficient. Injectionpumping systems deliver heating and cooling energy to a variety of terminal units, including chilled ceiling panels, chilled beams, fan coils, and heat pumps, in the same piping distribution system, even if each unit requires a different temperature. Like many hydronicbased-system developments, residential, and commercial radiant-cooling HVAC systems originated in Western Europe during the 1980s. For example, by lowering chilled panels below a ceiling, an individual panel's convection cooling component can be increased to approximately 370 to 475 Watt/h/m2 of the passive child element. This configuration resembles a chilled system when mounted below a ceiling and is passive because natural convection is the convective-cooling component. The installation space in the area under the double floors can be used for electrical and data cables, ventilation ducts, cooling and heating pipe work. Displacement diffusers can be installed close to the ducts and the under floor convectors integrated into the double floors. Cooling can be done by thermo active ceiling or flushfitted chilled ceiling. Luminaries, fire sprinklers, communication and acoustical systems can be attached in a synergistic fashion directly to the massive structural slab. This also means there is no need for expensive and material consuming suspended ceilings in buildings (in fact, they work against this system). One challenge with using active slabs that provide both radiant space conditioning and thermal energy is that it will not respond as fast to changes in sunlight, outside temperatures and internal loads as a standard overhead ducted air conditioning system. To solve this problem real-time control systems have to manage the load changes. As a result, it’s easier to operate the system with natural energies, particularly ground-coupled heat exchangers, or with solar systems. During the cooling season, the heavy reliance on the thermal mass of concrete slabs provides a “thermal lag” that offsets peak cooling loads, so that the size of the equipment

 

Fig. 5: Decision Flow Diagram, Th. Spiegelhalter

 

4. SOLAR STATISTICS

ASSISTED

HYBRID

SYSTEMS

 

Since 2006 more “than 100 micro-generation solar cooling and air-conditioning (A/C) systems have been installed in Europe. Their specific collector area is ~3 m2/kW for water chillers, or 10m2 per 1000 m3/h of air volume flow in desiccant systems. Their primary energy savings potential is between 30 60%, but these potentials are often not yet realized with Fig. 5: Decision Flow Diagram, Source: Th. Spiegelhalter the current systems (due to sub-optimal design, installation, and operation). Cost wise the systems have a pay-back period of 6 years (best systems) to over 20 years, at today’s energy prices.”(1) Most of the monitored solar cooling systems in the European Union have been installed in Germany (~40%), in Spain including the Northwest African Canary Islands (~28%), Italy (~9%), in France including tropical Guadeloupe (~6%). In comparison there is a greater diversity of climate zones in the U.S. than in most EUzones, except the EU-oversea locations in the Caribbean member states. It is challenging to be able to use European approaches in the US for significant adaptations in the hotter and more humid regions in the U.S. Southern States (Fig.4). Following are selected examples of existing and monitored systems in hot and humid climates with high internal loads. In

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many cases, the systems used familiar components and climate-control mechanisms in different ways than in the U.S., but there is little that experienced architects. engineers with mechanical contractors should find overly challenging in the U.S. As with all climate control systems, each building integrated micro generation system must be commissioned, serviced, maintained and monitored to ensure operation in compliance with design intent.

4.2. Hybrid Solar Thermal Driven District Cooling and Heating Plant at Los Angeles Valley College Campus, California, USA. (2009-) 34° 10′ 33″ N, 118° 25′ 90″ W

4.1. Hybrid Micro-Energy Generation with Desiccant Dehumidification and Ventilation Systems and Radiant Cooling in Thailand, (2006-), 13°45′N 100°29′E The strategy of Thailand's Department of Alternative Energy Development and Efficiency (DEDE) has been positive since they started a governmental subsidy programme for commercial customers in 2007: “37 commercially installed solar thermal systems between 50 and 500 m2 received subsidies in Thailand over the last two years. DEDE approved 17 applications in 2008, among them 9 hotels, 5 factories, 2 hospitals and 1 school – all in all, 4,000m2 of collector area. 2009 brought forth Phase II of the incentive programme, with 20 systems profiting from subsidies: 14 hotels, 3 factories, 1 hospital and 2 schools - a total of 3,000m2 of collector area. The biggest installation was a food factory with 499m2.”(2) In 2006 Vangtook and Chirarattananon studied already before the governmental subsidies desiccant dehumidified ventilation for radiant cooling systems in high latent load space such as operating theatres and hospitals under hot and humid climate conditions in Thailand. The temperature of the radiant cooled water was limited to 24ºC to avoid condensation. They found that the low heat reception capacity of the radiant panel would limit its use only to situations when loads were low, and they identified that desiccant dehumidified ventilation provides very dry air to decrease the supply air flow rate, because the humidity ratio islower than that obtained with a conventional vapor compression chiller used for all-air systems. They summarized that hybrid air-water conditioning system (water-air based with desiccant demudification) are desirable for buildings in hot and humid regions, like southeastern countries of Asia, where the risk of condensation is very high due to the low surface temperature in the radiant cooling panels. Another advantage they identified is that sensible and latent cooling load are decoupled and con-trolled separately, which means that control of humidity can be achieved better than with conventional vapor compressive systems. “Their results showed also that up to 44% primary energy demand could be reduced with the hybrid water-air-system, in comparison with a conventional all-air system.”(3)

     

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(Fig. 4), PV-Wind-Solar Thermal Hybrid Micro generation System in Los Angeles Valley College, Image courtesy Allenergyusa, Serge Adamian, 2010

(Fig. 5), above image: Campus Chilled Water Production and ICE Farm Auxiliary to Absorption Chiller, below image: Storage Discharge to Heating and Cooling Demand, Image courtesy Serge Adamian, 2010

The 1,231 kW solar thermal air conditioning micro generation project was completed last year in May 2009 at Los Angeles Valley College, one of the nine campuses of the LA Community College District (Fig. 4). As a demonstration project it is considered to install similar solar thermal driven air conditioning and space heating installations at all of its L.A. campuses to save electricity and to avoid future power outages during peak times within the LADWP utility infrastructure. The overall micro generation technology integration consists of central plant, solar thermal driven absorption chiller, hot water tanks, space heating, ice-on-coil thermal storage as backup to absorption chiller and off-peak cooling, PV, energy efficient lighting, and enterprise management system.

 

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

As solar thermal energy in combination with the absorption chiller is stored in insulated tanks, and used to offset peak electric rates and demand charges. It was estimated that the campus peak cooling load after completion of an additional new campus building was going to be 5,275 kW (1,500 tons). To meet the added cooling and heating loads the central plant capacity was expanded by replacing one of the two electric chillers with a new one capable of ice making, adding one new 1,231 kW (350 tons) Broad solar thermal driven absorption chiller, 497 SUNDA SEIDO 1-16 vacuum tube collector modules (7,952 tubes), and adding 2 new ice storage units to a total of 6 (Fig. 5). Hot water is collected in 3 insulated vertical tanks 469,391 L each (total 272,549 L) staged next to the central plant. The maximum allowed temperature at the solar hot water tanks is 110°C. During the summer season the solar hot water is directed to the absorption chiller for space cooling. The solar hot water system has the flexibility to bypass the absorption chiller in the winter for space heating. The ice storage and electric chillers act as backup/ auxiliary to the absorption chiller. Boilers serve as backup to the solar hot water tanks for space heating. The major innovation with the EnterprizeDX Building Management System is represented through the peak load, because the peak electric rate and demand charge period at LADWP territory is 1:00 PM-5:00 PM, Monday through Friday in the summer season (Fig. 6). The absorption chiller is turned on at 12:45 PM Monday through Friday and turned off at 5:15 PM to save peak electric rates and demand charges. Before 12:45 PM the cooling demand of the campus is met by melting ice. Once the absorption chiller starts operating, when the cooling demand exceeds the capacity provided by the absorption chiller, ice is melted to maintain the chilled water supply temperature. Because peak electric rates and demand charges apply during the weekdays in the summer, the absorption chiller normally operates on weekdays only. Thus, during the summer the hot water tanks are charged by the solar thermal collectors for 7 days per week and discharged only for 5 days (Fig. 7, 8). (4)

(Fig. 7.), Monitoring Excerpt: Sunny Day in Winter, Solar Hot Water loop with Solar Chiller on a Winter Day, Tue. Jan. 4th,

 

The first trending results using EnterpriseDX metering software was conducted by LACCD and ARUP from December 2010 to January 2011. The trending results show that the micro-generation solar cooling and heating system achieved a 53% overall efficiency, whereby the Chiller COP was measured with 0.71. However, the Chiller COP overall losses are recorded with 27% and the System Inefficiencies is with 20% (Fig. 8). (5)

                       

 

 

(Fig. 6) Trending using the BMS (building management system) EnterpriseDX software, diagram courtesy Serge Admanian, 2010

(Fig. 8), Data Visualizer Tool for analysis, Jan. 4th, 2011. Diagram courtesy Serge Admanian on behalf of LACCD and ARUP, January 2011

 

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The average daily kWh output during the two months monitoring of the Solar Chiller & HX2 was recorded with 6,872 kWh/day (23,447 kBtu/day), and the Chiller COP is calculated with 0.71. The lessons learned after the first winter monitoring are: to incorporate better quality sensors to improve the management and control systems performance in avoiding energy losses to insulate all exposed pipes add 3-way valve before heat dump heat exchanger use pool to dump the heat instead of cooling towers, and use condensing loop to heat the pool The next trending results for the hottest climate period in Los Angeles will be conducted between July and September 2011, when cooling loads are assumedly the highest.

    5. WORLD-WIDE NEGATIVE ENVIRONMENTAL IMPACT OF FOSSIL-FUEL DRIVEN ACSYSTEMS A critical growth in the competitive market for conventional fossil-fuel driven AC-systems can be observed worldwide due to increasing comfort expectations for cooling and dehumidification. “The number of sold units increased from about 26 million units worldwide in 1998 to more than 74,2 million units in 2007” is alarming. (6) Which technology is employed, small RAC split units, multi-split systems, centralized chilled water technology, centralized air handling units, depends strongly on regional markets and cultural attitude, politics, know-how of the trades, and practicing MEPs. Conventional cooling technologies exhibit several clear disadvantages:

 

· Their energy consumption and environmental impact is unacceptably high and GHG reduction goals are hard to match; · They cause high electricity peak loads and power outages in many states of the US and in similar world climate zones · In general, they employ refrigerants with a considerable global warming potential. In order to limit the negative impact on the energy consumption at peak load and causing increased pollution (global warming potential GWP), new environmentally sound concepts for small capacity range are of urgent importance. The utilization of micro-generated solar thermal energy to drive affordable heat-driven cooling machines is a way to address these problems. A well designed micro generation solar assisted air-conditioning system produces cooling with considerably less electricity demand than conventional air-conditioning systems. Furthermore, the working fluids used in sorption chillers and desiccant rotors will not contribute to

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global warming, contrary to most working fluids in conventional compression chillers

  6. CONCLUSION FOR POSITIVE TRENDS OF BUILDING INTEGRATED SOLAR MICROGENERATION COOLING SYSTEMS  

Thermally driven cooling design concepts with building integrated water-air-based distribution systems play a major role for energy efficiency in the building and utility sector as well in industrial refrigeration. Waste heat with poly generation, heat from co-generation with tri-generation, district heat and cooling to solar energy use have the potential to curb the ever increasing demand for conventional energies used for cooling purposes. Because of this, it contributes to lessening the dependence on “imported fuels and increasing military expenditures for resource wars and supply protection and to avoid CO2 emissions in the long run (7)”. As all the previous case study projects demonstrate, it also lowers electricity demand at times of peak loads; it increases the stability and costs of the electricity grids. As solar cooling is still an emerging technology, it faces many growth barriers which are different from other heating and cooling technologies. Because of these strong benefits, the market penetration in the U.S. of solar cooling should be better supported by governments. Major R&D efforts and training of all professional and decision making players involved are necessary to exploit the full potential of this promising technology in the U.S. Optimistic scientists and politicians in the European Union are expecting a major progress on system level for all sizes (small, medium, and large scale) towards single-effect systems with usual solar collector technology for heating and cooling with significant cost reductions for small capacity absorption and adsorption chillers with typical system operation temperatures of 70º to 110º C. “First Small chilli®Solar Kits are already on the European market for architects and planners with first operation experiences of small capacity systems (solar heat, biomass, CHP waste heat, process heat). These systems are available with specific cost ranges and an increasing level of standardization:

 

-5000 to 8000 EUR/kW in 2007 -4500 EUR/kW in 2008 -500 to 3000 EUR/kW are expected in the near future. The solar cooling hybrid kit consists of solar thermal collectors, hot water storage, pump-set, chiller, recooler, partly cold water storage and digital systems controller. The specific costs are without cold distribution and installation costs.”(8) But also building integrated hybrid systems for small, medium and large capacity using single-axis solar tracking with optical concentration will become increasingly efficient and cost-competitive for planners in the near future, when typical operation temperatures between 150–250ºC allow efficient large capacity ranges with dominant use of cooling for

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

industrial processes and large-scale buildings and communities. It is imperative, that all involved key players, researchers, planners, engineers, politicians, policy makers, and educators have to work together to success with innovative fundamental and applied research and development approaches to increase energy efficiency (COP by greater than 50 percent), and reduce GHG emissions due to cooling and heating of buildings.

   

7. ACKNOWLEDGMENTS W. Hoenmann, F. Nuessle, „Kuehldecken verbessern Raumklima. Kuehldecke und Raumlueftung“, Fachinstitut Gebaeude-Klima e.V., BietigheimBissingen, Germany, 1991. Robert A. Meierhans, Slab cooling and earth coupling, ASHRAE Trans.,pg. 99, 1993. IEA International Energy Agency, The Solar Heating and Cooling Programme, established in 1977, France. http://www.iea-shc.org/ Dr. Hans-Martin Henning. “Solar-Assisted Air-Conditioning of Buildings - A Handbook for Planners”, Berlin New York, Springer Verlag Edition, ISBN-10: 3211730958, ISBN-13: 9783211730959, 2007. Thomas Spiegelhalter: “Innovative Building Integrated, Solar-Assisted Air-Water Space Conditioning Systems with Dehumidification, and Thermo-Active Cooling Systems for Hot and Humid Climates”, ASES SOLAR 2010 Conference Proceedings, USA, 2010

 

(7) Stockholm International Peace Research Institute (Top Global Think Tank), Research on questions of conflict and cooperation of importance for international peace and security http://www.sipri.org/yearbook/2009/05 (8) H. Beckmann, Dr. U. Jakob. ”Solar Cooling Kits im kleinen Leistungsbereich“. Fachforum Klimatisierung mit Solarenergie, SolarNext AG, Bauzentrum Muenchen, pg. 5, Sept. 23, 2008.

   

9. INTERVIEWS

 

Serge Adamian, HVAC Engineer Los Angeles, Interview: Monitoring Data and Results for Los Angeles Valley College, January 2011 Prof. Elmar Bollin, Director of the Research Group NET –, University of Applied Sciences Offenburg, and Prof. Ursula Eicker, University of Applied Sciences Stuttgart, zahf-net Baden-Wuerttemberg Intl., Interviews at the German Symposium “Sustainable Energy Technology in Germany and the U.S.”, Los Angeles, Nov. 2009. Christoph Ingenhoven, Ingenhoven Architekten, Düsseldorf, Germany, Interviews “A Green Future”, at USC, Los Angeles, USC Energy Institute, and GLUMAC, Oct. 2008. Robert Meierhans, Indoor-Climate-Engineer Zuerich, Switzerland and professor at the Department of Urban Design at Wuhan University, China. Dialog and joined Solar Design Teaching at USC in Los Angeles, Fall 2004.

8. REFERENCES (1) Intelligent Energy Europe. ”Project Key Issues for Renewable Heat in Europe (K4RES-H). ESTIF EUROPEAN SOLAR THERMAL INDUSTRY FEDERATION, Solar Assisted Cooling, WP3, Task 3.5 EIE/04/204/S07.38607”, pg. 12, Aug. 2006. (2) Solar Thermal Utilization in Thailand, Somsak Chutanan, World Alternative Energy Sciences Expo 2009 Impact Exhibition, Muang Thong Thani, March 6, 2009. (3) Prapapong Vangtook and Surapong Chirarattananon, “An experimental investigation of application of radiant cooling in hot humid climate” Energy and Buildings, Volume 38, Issue 4, pp. 273-285, April 2006. (4) Product review and interviews with Project Engineer Serge Adamian, MS, MBA, PE, CEM, SunChiller ALLenergie USA, Inc., Glendale, CA, USA, http://www.allenergyusa.com/ http://www.sunchiller.com/ , Febr. 2010, Nov. 15 (5) Serge Adamian, Carlos Urrutia. “The Application and Management of Renewable Energy Resources Project Location Los Angeles Valley College”, ICEPAG International Colloquium on Environmentally Preferred Advanced Power Generation Angeles Community College District (LACCD) Feb. 9, 2011 (6) B. Griffith, N. Long, P. Torcellini, R. Judkoff, D. Crawley and J. Ryan. “Assessment of the Technical Potential for Achieving Net Zero-Energy Buildings in the Commercial Sector” National Renewable Energy Laboratory, U.S. Department of Energy, 2010

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ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBN th xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Approach to classification and evaluation of naturally cooled buildings Gianluca CADONI Laboratoire ABC, ENSA-Marseille, Marseille, France Thesis Director: Stéphane HANROT; Co-director of thesis Jean-Louis IZARD ABSTRACT: Passive cooling systems are the combined technical solutions and design strategies used to promote low carbon cooling. The aim of our research is to evaluate the performance and efficiency of these systems, why and when they do not function correctly, and to assess what impact they have on architectural design. The objective of this methodological approach is to allow us to compare passive cooling systems in contemporary architecture in different parts of the world. Our analysis was carried out by dividing each building into its separate architectural elements in order to analyze how each of them function and how they function together. Keywords: Passive cooling system, low carbon cooling, building-system, an architect’s position, methodological approach

1. INTRODUCTION 1.1. Article plan The present article will explain the methodology used to analyze, compare and evaluate passive cooled buildings. The aim of the present research is to estimate the efficiency of these systems, the reason for their success or failure and what impact they have on architecture. Thus, an analysis and evaluation methodology was set up to verify the viability of passive cooling systems in contemporary architecture. Two tools were set up to evaluate the buildings: firstly, a data matrix, which we shall call a critical database that allows for comparisons to be made between qualitative and quantitative data, and secondly, files on each building that contain both quantitative data and a critical analysis of their architecture. Firstly, the files serve as instruments of communication. Moreover, the architectural appraisal they contain aims at understanding the architect’s position regarding the integration of passive cooling systems. To explain the methodological approach, I will use the iGuzzini headquarters in Recanati, Italy, designed by the architect Cucinella, as an example. 1.2. Presentation of the issues raised by this research We consider that the number of contemporary buildings that adopt passive cooling as a design strategy to promote low carbon cooling is very limited. The PHDC (Passive and Hybrid Downdraught Cooling) research group, for example, estimates that no more than 50 buildings, cooled by evaporative cooling systems, have been built worldwide over the past 15 years. Our methodological approach aims at comparing and evaluating summer bioclimatic performances of buildings, as well as understanding the integration of passive cooling systems in architecture. The adopted method has led us to compare buildings with different functions in different parts of the world. We have put into place a number of indicators that will

enable us to make critical analyses and comparisons of different buildings. These indicators will also help us to analyze both summer and winter bioclimatic performances.

2. METHODOLOGY ADOPTED BUILDING ANALYSIS

FOR

2.1. Methodology-based research The buildings were studied as systems, the objective of which was to guarantee the thermal comfort of users. The analysis was carried out by dividing the building into progressively smaller architectural devices [1], starting with territorial implantation and concluding with design details. The functions within the building system were also analyzed, based on LE MOIGNE’s [2] systemic approach, by adapting the method’s four precepts to our problem. The aim of this division into individual elements was to analyse each element following its function within the whole system. The building was analyzed on different definition levels ranging from a territorial scale down to architectural detail: territory, groups of buildings, single buildings, entities, divisions and constituent parts. In order to evaluate and divide the building up we followed the method used by S. HANROT [3], adding an extra level of definition to the existing research: systems to improve user comfort. This definition level was inserted between entities and divisions, thus abiding by the rule that definition levels are in `cascading` order, whereby the first level includes the second which includes the third, etc... The vertical breakdown of buildings gave rise to a matrix of both quantitative and qualitative data, which we designated as the critical database. The evaluation of the architectural devices followed S. HANROT’s method [4], with critical appreciation for them ranging from 1 to 6: 1=very poor, 2= poor, 3= sufficient, 4=good, 5=very good, 6=excellent. Hence, by using these grades, the bioclimatic performances of buildings could be evaluated. A satisfactory mark (3)

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

corresponded to a well-designed device that was congruent with the building system. Lower grades signified that the device was not congruent with this system and may therefore affect its functioning. It may even have reached a critical point – the point at which a single factor causes the non-functioning of the building system - where the building was unable to guarantee user thermal comfort. On the other hand, higher grades signified that the device contributed to the functioning of the building system and it improved user thermal comfort. 2.2. Choice of buildings The first difficulty was choosing the buildings to be analyzed. Precise parameters were defined in order to determine choices. The buildings had to conform to the following criteria: (1) the architect’s or structural engineer’s objective is to design a building that ensures user thermal comfort by creating a low carbon building. (2) Absence of mechanical airconditioning systems (AC), but a building-system that works actively to reduce overheating. (3) Access to scientific data. The iGuzzini Group building corresponded to the above criteria. (1) The project of the architect, M. Cucinella, aimed at reducing energy costs and environmental consequences. (2) The cooling strategies were: efficient protection against overheating and a passive downdraught cooling system, which works thanks to a central atrium that acts like a chimney to extract air. In the higher part of the atrium and in the offices, automatic windows work in synchronisation with a weather station. The weather station controls the internal and external temperatures and can open or close windows according to different programs. To improve downdraught cooling, the thermal mass of the building was exposed to the air flux. (3) Many different types of research were carried out on this building.

Figure 1: composition of critical database.

One of the aims of the critical database is to compare different passively cooled buildings. Given that over 60 architectural devices have been analysed, the amount of data is too large for easy comparisons to be made between any two buildings. To resolve this problem we chose the most significant indicators - those which are badly designed or built can jeopardise the bioclimatic functioning of a building - and created a radar graph that had 11 indicators with an average mark attributed to each element.

3. CREATION OF THE DATABASE The critical database is a data matrix analyzed at different definition levels. It contains technical and quality data as well as critical analysis data as well as the grades that enable one to evaluate the bioclimatic performances of buildings. The critical database is broken down into the following definition levels: territory => latitude, longitude, the climate, heating degree days, etc. Group of buildings => implantation, orientation, morphology of the group, etc. Entities=> morphology, volume and shape of buildings, etc. Systems to improve user comfort => cooling, natural lighting, thermal inertia, control strategy (automatic or human) etc. Divisions => outward vertical divisions, outward horizontal divisions, partitioning, patios, etc. constituent parts => inert materials, types of glass, thermal insulation etc. Each device is accompanied by a short description and is assigned a grade using the method that we have described.

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Figure 2: most significant indicators for the iGuzzini building.

The most important indicators are: Morphology of the group: defines the shape and the layout of the buildings in the total operation. Usage: defines how the building functioned at the time of researching. Functional plan: defines the organizational structure of the building. Shape coefficient: defines the ratio between the 3 outside surface and the volume of a building m²/m . Rate of active glazing: defines the ratio between the glazed surfaces and the peripheral floor shape m²/m². Natural lighting: defines what percentage of daylight penetrates the building. Thermal inertia: defines the susceptibility of keeping a stable temperature. Functioning of the passive cooling system: defines how passive cooling systems function and how they are adapted to the building.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Control strategy of building services, both automatic and human: defines the control mode of passive cooling systems and how they relate to the whole building. Partitioning: defines the internal barriers preventing air flowing through buildings. Solar protection of vertical surfaces: defines the presence and quality of sunscreens. If one or more of these indicators is badly conceived or implemented, then the entire building system cannot guarantee the thermal comfort of its users. The image that this radar graph provides concerning the iGuzzini headquarters is easily interpreted. The building is well conceived and built, although two badly-ranked indicators underline certain weak points. The critical indicators are: (1) usage and (2) the rate of active glazing. (1) Usage: the function of the headquarters contains cultural constraints which are contradictory to the bioclimatic strategies adopted by the architect. The designers set the comfort temperature at 26°C within the conception of the building, but due to the wearing of clothes such as jackets and long-sleeved shirts, typical of managerial offices, the 26°C temperature did not guarantee a state of comfort. Moreover, the best performances in downdraught strategies occur when air flux is not hindered, thereby promoting open space architecture. The top floor of the iGuzzini headquarters is composed of small offices cooled by AC, and thus, we can say that the building’s usage contradicts the architect’s strategies to guarantee user comfort. (2) The rate of active glazing is an indicator introduced to link the glazed areas to the nearest floor space. The glazed area is calculated on the surface area of the floor space, with the influenced area being defined by a 5meter wide strip along the perimeter of the building. This indicator allows us to evaluate the surface area of the glass walls, given that they are a problem for the bioclimatic performances of the building. The image below shows the iGuzzini building’s floor space influenced by glazing.

Figure 3: representation of rate of active glazing in the iGuzzini building.

The other indicators of this building highlight how well it was designed and built. The morphology of the group is compact and the functional plan is efficient with the central patios containing all the necessary vertical and horizontal distributions. The patios act like chimneys to extract warm air, and the shape coefficient demonstrates that the building has a very compact volume. The natural lighting is very well designed as the central patio enables light to reach the centre of the building. Thermal inertia is not optimal because, due

to the large glass bays, the architect had to limit the thermal inertia of the building and concentrate it within the floor slabs. The functioning of the passive cooling system is well adapted to the use of the building. The control strategy is an automatic one, with a weather station automatically managing the opening and closing of the windows. The weather station functions well, although occasionally it conflicts with the employees` space usage. Over the first two years of building usage, the control strategy program was changed many times in order to find the best equilibrium. The partitioning of the building was well studied in relation to the passive cooling system, where the open-space offices allowed air to circulate freely. The solar protection was very well studied and several experiments were carried out in designed phases by the Ove Arup company. The average grade of all sixty devices was the final indicator.

Figure 4: iGuzzini building. KIRIOCOMUNICAZIONE [23]

The IGuzzini building has an average grade of 3,60. This building was analyzed by EULEB [5] who wrote: “After the initial period of the building’s life, user dissatisfaction recommended opening the high level louvers and changing the temperature value at which the windows open. The failure of this second temperature control attempt has led to manual control of the louvers in order to allow users to change the temperature in each working environment. The resulting measurements covered the entire period during which the different types of operating modes were tested, but, as shown, the hybrid ventilation system has not been sufficient to establish both winter and summer thermal comfort conditions. For this reason, except in spring and autumn, the building has operated under the mechanical mode for the remainder of the year. In spring and autumn, the PMV values have not always been acceptable, even if the CO2 values have reached the right levels”. This confirms our analysis: the building is well designed and built, although some critical aspects risk jeopardising the bioclimatic performances of the building. This methodological approach has enabled us to compare different buildings in different parts of the world. In this article, we are comparing the iGuzzini building with the French Lyceum in Damascus.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 5: French lyceum in Damascus. 02KM817, [24]

We used the second tool created to improve the knowledge of the architect’s position in relation to the integration of passive cooling systems. While the data matrix facilitates understanding in how passive cooling systems function, files on buildings enable us to highlight their architectural aspects and communicate the results of the research.

iGuzzini building logo is a sectional diagram showing the type of passive cooling, how it functions within the central patio, the type of roof, the position of thermal inertia and the type of façade. The second part details the devices analyzed in the critical database, with some images helping us to understand better the synthetic analyses. The iGuzzini example file demonstrates how the critical database and files are linked. Moreover, the files contain the images and graphs, which illustrate and explain the analyses more clearly and coherently.

Figure 6: radar-graph of comparison between the iGuzzini building and the French Lyceum in Damascus.

Comparing different buildings can provide us with some interesting information about the causes of success or failure of building systems. The graph shows us that the two buildings have a similar average grade, but the Damascus building does not have any critical indicators that may compromise the functioning of the building. This methodology enabled us to compare them although the buildings are in different locations.

4. CREATION OF FILES 4.1. Aims of the database and files To improve the knowledge of the architect’s position in relation to the integration of passive cooling systems, we used the second tool that we created. While the data matrix enables us to understand the way passive cooling systems function, files on buildings allow us to focus on their architectural aspects and communicate the results of the research. Today, there is a keen debate on this subject. According to Architect Mario CUCINELLA “we are in a transitional architectural phase. The issue of sustainability… forces us to re-examine our design approach…some architects continue to make projects in the old way and all they do is add some devices to reduce energy consumption. We should instead interpret architecture as a whole and carry out projects with the active contribution of different actors, such as structural engineers, thermal engineers etc.”: the Bologna SAIE conference, October 2009.

Figure 7: first page of files with detail of synthetic logo.

The third part is devoted to architectural reviews that aim to analyze the architect’s position in relation to the integration of passive cooling systems. Previous analyses have allowed us to understand the bioclimatic functioning of the building. The methodological approach that we used has enabled us to assess the different architectural devices and to contrast different buildings. The architectural reviews aim at replying to another question: what is the impact of passive cooling systems on architecture?

4.2. Content of files The layout of building files derives directly from the critical database, and is divided into three parts: A synthetic, analytical description of the building appears on the first page, along with the file index, the building’s geographical and climatic positions and a synthetic logo of the building that facilitates understanding of how the building functions. The

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Figure 8: a page of files.

The images presented in the files have helped us to understand this aspect. Moreover, when data is accessible, the results of pre-construction

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

simulations and the real performances of the buildings, as well as post-occupancy assessments, are presented and analyzed. These supplementary analyses have added to our knowledge of the building and of the decisions made by architects to obtain the final results. As we can see, the architect Cucinella opted towards complete integration of passive cooling systems into the architecture. The aspect of the building is contemporary and the presence of passive cooling systems is difficult to envisage. The glass walls, typical of this kind of commercial building, protected by sun screens do not indicate that any particular attention has been paid to environmental problems. The first objective of the architect is to create “una bellissima architettura” (Elisabeth FRANCIS vicepresident of the cabinet MCA, interviewed in Bologna SAIE October 2009), thereby naturally integrating, from the first design phases, bioclimatic concepts to create a low carbon building. The building does not have an environmentally explicit or “educational” aspect, but rather that of a commercial building that aims to represent the firm that it houses. The two buildings, the iGuzzini building, designed by Cucinella, and the French Lyceum in Damascus, designed by architect Ives Lion, were chosen to be analysed due to the different design approaches. Those working with Lion decided to take inspiration from traditional Mediterranean architecture. The solar chimneys, guaranteeing the continuous circulation of air are reminiscent of the Iranian Bagdirs. In this project the ventilation system had a “pedagogical aim”, and relied on the active participation of the pupils and teachers to adjust the vents that let air in and out to guarantee thermal comfort. This pedagogical objective is made explicit in the architectural design itself, with the architect wanting users to know immediately how the building works. This architectural approach is linked both to the building functioning and to the architectural style.

enable us to compare many buildings and to know when, how and whether passive cooling systems work well or not. We aim to create a database of rules that will allow the architect to reduce the errors to a minimum.

5. ACKNOWLEDGEMENTS I would like to thank all the people who contributed to the article, namely: The Sardinian Region, which financed the Master and Back Research Program, Jean-Louis IZARD, Stéphane HANROT, and Elisabeth FRANCIS, the vicepresident of the Mario CUCINELLA architectural company.

Figure 5: French lyceum in Damascus. 02KM817, [24] Conclusions

It was possible to compare two architectural approaches and two different buildings thanks to the critical database. The architectural appraisal has enabled us to understand the decisions made by the architects. The data matrix has allowed us to understand better the functioning of passive cooling systems in the same way as the files have allowed us to give prominence to the architectural aspects and the architect’s position regarding the integration of cooling systems in his project. Although only two buildings have been compared in this article, our methodological approach will

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

6. REFERENCES [1] Definition of dictionary CNRTL - device : set of elements arranged for a precise propose, from: http://www.cnrtl.fr [Accessed 20/05/2010] [2] LE MOIGNE Jean-Louis, “la théorie du système général théorie de la modélisation“, Collection Les classiques du réseau intelligence de la complexité, internet, 2006, 360 pages. [3] HANROT Stéphane, “Modélisation de la connaissance architecturale pour un outil de CAO intelligent“, Plan Construction et Architecture, 1989, 246 pages, ISBN 2100 85419-7 [4] HANROT Stéphane, avril 2005, “Evaluation relative de la qualité architecturale : une approche par le point de vue des acteurs“, « Cahiers Ramau - La Qualité Architecturale - Acteurs Et Enjeux », Editions De La Villette, 2009, N° 5, ISBN 978-2-915456-47-9 [5] Intelligent Energy Europe, “EULEB – European high quality Low Energy Buildings“, 2005-2006, from: http://www.euleb.info/ [Accessed 15/05/2010] [6] COOK Jeffrey, “Passive Cooling“, Edition M.I.T. Pres Cambridge 1989. 593 pages. [7] GIVONI Baruch, “Passive end low energy cooling of buildings“, Edition John WILEY & Sons 1994. 263 pages. [8] GIVONI Baruch, “Climate considerations in building and urban design“, Edition John WILEY & Sons 1994. 464 pages. [9] SANTAMOURIS M., ASIMAKOPOULOS D., “Passive Cooling of Buildings“, Edition James & James, 1996. 472 pages. [10] Auteurs divers, “Confort d’été, rafraîchissement ou climatisation des bâtiments”, (journées techniques, 14 et 15 sept 1995). Edition ADEME 1995. 287 pages. [11] SANTAMOURIS M., ADNOT J., ALVAREZ N., KLITSIKAS N., ORPHELIN N., LOPES C., SANCHEZ F, “Cooling the cities, rafraîchir les villes“, Edition Ecole des Mines Paris 2004. 263 pages. [12] IZARD Jean-Louis, “Architectures d’été“, Edition EDISUD 1993. 141 pages. [13] BUONO M., “L' architettura del vento. Soluzioni tecnologiche per il raffrescamento passivo“, Edition CLEAN 1998. 144 pages [14] STEELE J., “An Architecture for people: The complete works of Hassan Fathy“, Edition Academy Editions 1997. 208 pages.

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[15] FATHY Hassan, “Construire avec le peuple : Histoire d'un village d'Egypte Gourna“, Edition Martineau 1970. 310 pages. [16] KWOK G., AIA, GRONDZIK T., PE, “Green studio HandBook“, Architectural Press, Amsterdam 2007. 378 pages. [17] GROSSO Mario, “Il rafrescamento passivo degli edifici in zone a clima temperato“, Maggioli Editore, San Marino 2008. 648 pages. [18] R. SCHIANO-PHAN and B. FORD, Post Occupancy Evaluation of non-domestic buildings using downdraught cooling: Case studies in the US, 25st PLEA Passive and Low Energy Architecture, Dublin - Ireland (2008). [19] GAUZIN-MÜLLER Dominique, “strategie climatique en milieu aride“, « EcologiK », Architectures à Vivre, 2009, 08, 72-81, 19617267 [20] SIMONELLI Giuliano, “ediliziainrete“, 1998, from: http://www.ediliziainrete.it/scheda_real.asp?r ec=530 [Accessed 05/09/2009] [21] Intelligent Energy Europe, “EULEB EUropean high quality Low Energy Buildings“, 2005-2006, from: http://www.learn.londonmet.ac.uk/packages/ euleb/fr/home/index.html [Accessed 15/02/2009] [22] Architectural Association School of Architecture Graduate School, “idea“, 9 January 2003, from: http://www.unige.ch/cuepe/idea/frm_one.htm [Accessed 04/04/2009] [23] KIRIOCOMUNICAZIONE, “MC Architects“, from: http://www.mcarchitects.it/index.php?id=19& projid=100 [Accessed 15/01/2011] [24] 02 KM 817, Morin Gaël, Lioselet Axel, “Ateliers Lion“, from: http://www.atelierslion.com/ateliers_lion.swf [Accessed 20/03/2010]

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Passive & Hybrid Cooling for Production SingleFamily Housing Thomas A. Gentry1 1

University of North Carolina at Charlotte

ABSTRACT: In many warm-humid regions of the world the opportunity exists to offset a significant portion of the conventional air conditioning load of buildings with various forms of ventilation. This paper investigates the feasibility of the opportunity for detached single-family production housing in Charlotte, North Carolina. Integrating passive stack-effect ventilation with mechanical whole-house ventilation and PCM (phase changed material) gypsum board, it outlines a strategy that is user-friendly to production housing designers, developers, materialmen and tradesmen. There are two reasons why it is important to address this issue. First, in the United States detached single-family production housing accounts for more new construction, measured in square feet or dollars, than any other type of building; consequently, modest improvements in energy efficiency for this building type result in significant aggregate reductions in greenhouse gas emissions. Second, several decades of low cost energy has resulted in conventional air conditioning being the sole method for cooling production housing. The industry needs cost effective alternative cooling methods to help preserve markets. Keywords: natural ventilation, fan-forced ventilation, high thermal mass with night flushing, production housing, single-family housing

1. INTRODUCTION In many warm-humid regions of the world the opportunity exists to offset a significant portion of the conventional air conditioning load of buildings with various forms of ventilation. This paper investigates the feasibility of the opportunity for detached singlefamily production housing in Charlotte, North Carolina. Integrating passive stack-effect ventilation with mechanical whole-house ventilation and PCM (phase changed material) gypsum board, it outlines a strategy that is user-friendly to production housing designers, developers, materialmen and tradesmen. There are two reasons why it is important to address this issue. First, in the United States detached single-family production housing accounts for more new construction, measured in square feet or dollars, than any other type of building; consequently, modest improvements in energy efficiency for this building type result in significant aggregate reductions in greenhouse gas emissions. Second, several decades of low cost energy have resulted in conventional air conditioning being the sole method for cooling production housing. The industry needs cost effective alternative cooling methods to help preserve markets. Using a design developed by the Laboratory of Innovative Housing (LIH) at the University of North Carolina Charlotte this paper outlines the work being conducted by the LIH to promote the incorporation of passive and hybrid cooling into detached singlefamily production housing.

2. PRODUCTION HOUSING The vast majority of new single-family detached housing built in the United States is produced as a market commodity by production developers and trades. As with most commodity manufacturers –

whether they are producing cars, appliances or shoes – the goal is to optimize production in terms of profits. While this description may sound harsh and somewhat cynical it does describe a system that is easy to understand. Any changes that are going to happen without government regulation are only going to happen if it improves the bottom line.

Figure 1 - LIH Production House with Modifications

3. CLIMATE & DESIGN STRATEGIES Charlotte, North Carolina is located in a mild temperate climate. In an average year, heating is required for 6,077 hours, and cooling is required for 1,786 hours. More than half of the cooling load can be addressed through natural ventilation and/or fanforced ventilation. This is based on data produced with Climate Consultant 5.0. [1] Providing high thermal mass with night flushing reduces the need to use conventional air conditioning by an additional 265 hours per year. The challenge is to affect these strategies in production housing. [2]

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3.1. Natural Ventilation The model building codes used for single-family detached housing in the United States require the use of operable windows to provide natural ventilation; however, there are two problems with the requirements that routinely result in inadequate window arrangements for passive cooling by natural ventilation. The first problem is the minimum area of operable windows that is required is based on providing enough ventilation to maintain indoor air quality. With the exception of periods when the indoor temperature is only a few degrees above the desired temperature, cooling with natural ventilation requires significantly more ventilation than what is needed to maintain indoor air quality. The second problem is there are no requirements for locating the operable windows to promote natural ventilation. Quite often there is only one window for each space that is expected to function simultaneously as an inlet and an outlet for air. When there are multiple windows in a space it is not unusual to have all of them located in a single wall with the operable portions at the same height. Again, the expectation is that the undifferentiated configuration will function as an inlet and an outlet for air. Expecting developers to install more windows solely on the merits of accommodating passive cooling with natural ventilation is unrealistic, given

the unit cost of windows is higher than the unit cost of most residential exterior walls. With that in mind, designers must be more critical when selecting window locations and they must demonstrate a benefit to the bottom line in providing additional windows. Computation fluid dynamics (CFD) software is the tool for analyzing window locations and sizes to accommodate passive cooling with natural ventilation. It generates three dimensional models of air movement, heat transfer and temperature within spaces, and presents the data numerically and graphically. The problem is, with few exceptions, residential designers do not use the software because there are no incentives for them to invest the time and money. Window manufacturers are the stakeholder that most directly benefits from using more and larger windows, so it makes sense that they should provide the CFD analysis, and/or the incentives for designers to provide the analysis. One possible approach for the window manufacturers is to provide an easy to use web based analysis/design tool similar to the luminaire layout tool, Flashindoor, that Cooper Lighting provides. [3] The incentive for the designer is a tool that generates the required luminaire layouts in less time than it takes using a worksheet and calculator. The problem with this type of approach is that it provides no direct incentive for production developers to use more and/or larger windows. There needs to be a bottom line benefit.

Figure 2 - Climate Consultant 5.0, Natural and Fan-Forced Ventilation Cooling

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Figure 3 - Climate Consultant 5.0, Natural and Fan-Forced Ventilation Cooling with High Thermal Mass and Night Flushing

3.2. High Thermal Mass

4.1. Developers vs. Homeowners

Introducing high thermal mass into single-family detached housing in the United States is challenging because the leading structural system is Western Platform (lightweight wood construction). The materials that are traditionally used to provide high thermal mass with passive heating and cooling strategies – masonry and containerized water – are too heavy to be supported by a system developed to carry live loads of 40 pounds per square foot. Furthermore, the building systems that use the traditional thermal mass materials are more costly to construct than Western Platform. What is needed is a lightweight system that is compatible with Western Platform and no more expensive to install. One system that is showing promise is gypsum board containing micro-encapsulated PCM (phase change material). ThermalCORE™ is the PCM gypsum board manufactured by National Gypsum, [4] and it is currently being evaluated by the LIH. The advantage of this type of thermal mass system is that no construction modifications are required to use the system. It only requires substituting one gypsum board product for another. The disadvantage of this system is the additional cost of the material, which goes straight to bottom line of production developers.

To have natural ventilation and high thermal mass with night flushing become viable design strategies for production housing there needs to be a benefit to the developers’ bottom line; however, there is no benefit in increasing the cost of windows and gypsum board, when the cost of energy is not included in the bottom line. This is where the disconnect occurs. The cost of materials is the developers’ responsibility. The cost of energy is the homeowners’ responsibility. The developers see no connection between their bottom line and the cost of energy for the homeowners. What the developers are beginning to see is the connection between marketing and the cost of energy for the homeowners. An ever increasing number of developers are voluntarily participating in the Energy Star Program that is administrated by the United States Environmental Protection Agency. They are doing so because prospective homebuyers associate added value with Energy Star, much in the same way they associate added value with granite countertops. Both are perceived as features –physical pieces – that make the house more marketable. This is particular interesting because Energy Star is about energy performance but in the world of production housing Energy Star performance has been usurped by marketing campaigns. Unfortunately, or fortunately, depending on how important it is to have the goal align with the environmental and social benefits, the performance

4. FINANCIAL APPLICABILITY These approaches to cooling are financial applicable to developers and homeowners.

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of passive cooling via natural ventilation and high thermal mass with night flushing has not been usurped by marketing. It is unfortunate if the goal is to get developers and homebuyers to adopt the strategies as features with intrinsic value, because it

is unlikely these strategies will be adopted by marketers. It is fortunate if the goal is to get developers and homebuyers to begin to thinking more critically about the return on investment (ROI) for housing.

Figure 4 - DesignBuilder CFD Model for LIH Production House with Modifications

4.2. ROI for Natural Ventilation Housing in the United States became an investment instrument shortly after the Federal Housing Administration (FHA) and the Department of Veterans Affairs (VA) established their loan programs in the mid 1900s. Subsidized by the federal income tax deduction for mortgage interest, housing remained a sound investment for most homeowners until the market collapsed in 2008. Today, housing developers are struggling to modify their antiquated business models as they try to find the market. It is similar to what the American auto industry faced in the 1980s when their outdated business models allowed foreign competition to capture the market. Returning to the notion that there needs to be more critical thinking about ROI, the current lack of a market for most developers has motivated some to look at financial opportunities that were once considered too roundabout to be marketable to potential homebuyers. This is not to say developers no longer fixate on the bottom line. What is being said is the scope of what impacts the bottom line has gotten wider. Two of the developers in the Charlotte area that are deep into this process are working with the LIH to develop designs that employ passive cooling via natural ventilation and high thermal mass with night flushing. Both of them were working with

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the LIH before the collapse of the housing market to explore the marketing of “green housing” in the area, so making the decision to think more critically about the ROI for natural ventilation was not difficult for them. Going into the details of how to determine the ROI for natural ventilation is beyond the scope of this paper, but an overview is not. 4.3. The Process As stated earlier, more than half of the cooling load for housing in the Charlotte area can be addressed through natural ventilation and/or fan forced ventilation. Additional cooling can be realized by including high thermal mass with night flushing. Knowing this, and the annual cooling degree-days, building envelope u-factor, HVAC efficiencies, and utility rates it is possible to determine total energy savings in dollars. Using a CFD application it is possible to determine the quantity, sizes and locations of windows needed to optimize passive cooling. It is also possible to determine the benefit of using a whole house fan to provide hybrid cooling. Quite often the additional energy savings of transforming a purely passive system into a combined passive and hybrid system justifies the cost of the equipment. Knowing the extent of the additional windows and equipment makes it a simple

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

task for the developer to cost out the items, and calculate how much it will increase the monthly mortgage payment for the homeowner. When interest rates are low and utility rates are high –as they are now – it is possible to offset every dollar increase in the monthly mortgage payment with a dollar decease in the monthly utility bills. This approach improves the ROI for the prospective homebuyer in three ways. 1. It dampens the financial impact of increasing utility rates. 2. It allows for greater accumulation of equity by transferring a portion of the utility payments to the principle on the mortgage. 3. It reduces their federal income tax burden by transferring a portion of the utility payments to interest on the mortgage, which is tax deductible. All the developer needs to do is package these into a feature. This approach also provides benefits to the developer. 1. It provides access to a market of homebuyers seeking housing that is environmentally and financially more sound. 2. With profits typically being a fixed percentage of the cost, it increase profits by increasing the cost per house. An astute developer will identify financing opportunities for homebuyers that take into account the financial benefits for the homebuyers in transferring monthly utility expenditures to the mortgage.

5. DEMONSTRATION PROJECT One developer, who is working with the LIH, has been using a more environmentally sustainable approach with the horizontal development – infrastructure and site improvements – of communities he has developed in the past few years. He is now taking the same approach to the vertical development – housing and other buildings – on his next community. The project has roughly 900 housing units, as well as some commercial and light manufacturing. Features for the housing include; heating and cooling systems that use district energy, compact floor plates, greater use of local materials, and more. Passive and hybrid cooling for this kind of project is an ideal fit. What is particularly telling about this project is that in a time when most projects are struggling to find investors and gain municipal support, the developer of this project has had relatively few problems securing these stakeholders.

housing. Now that the housing industry has to rethink how it does business, the benefits of passive and hybrid cooling via natural ventilation are easier to see.

7. ACKNOWLEDGEMENTS The rendering titled, “LIH Production House with Modifications” was produced by Professor John Nelson. The rendering titled, “DesignBuilder CFD Model for LIH Production House with Modifications” was produced by Michelle MacDonnell, Research Assistant and Masters of Architecture candidate.

8. REFERENCES [1] Climate Consultant 5.0, Department of Architecture and Urban Design University of California, Los Angeles. [2] Ibid [3] Cooper Lighting, Flashindoor 1.33 Build by Lighting Analysis, Inc. provides luminaire layouts using IESNA methods and recommendations. Follow this hyperlink to an example for the Neoray Direct/Indirect Suspended Luminaire Shell II, http://www.cooperlighting.com/iesCalculator/Flas hIndoor.cfm?fp=/specfiles/ies/NeoRay/Suspended/Shell/201IP/&fn=201IP-S-P-2T8.ies [4] National Gypsum. ThermalCORE™, http://www.thermalcore.info/product-info.htm, March 7, 2011.

6. CONCLUSION Passive and hybrid cooling via natural ventilation has been and continues to be well suited for production single-family housing in the United States. While this paper focuses on a case study in Charlotte, North Carolina, similar opportunities do exist in temperate regions throughout the United States. Unfortunately, the benefits of using this technology were not widely recognized when quick profits could be realized with less energy efficient

HVAC - EQUIPMENT AND REGULATION (COMPLEMENTARY TO DESIGN)

669

BUILDING PHYSICS (HYGROTHERMIC AND ACOUSTIC)

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The influence of thermal properties of the envelope components on the thermal performance of naturally-ventilated houses Enedir GHISI, Ana Gabriela S.A. CARDOSO Federal University of Santa Catarina, Department of Civil Engineering, Laboratory of Energy Efficiency in Buildings, Florianópolis-SC, 88040-900, Brazil ABSTRACT: The objective of this article is to assess the influence of thermal properties of the envelope components on the thermal performance of naturally-ventilated houses in Brazil. Twenty-nine rooms in five houses located in Itaberá, southeastern Brazil, were selected for measurements. Internal air temperatures were measured over 41 days, from 26 December 2005 to 4 February 2006, in the 29 rooms. External air temperature was measured outside one of the houses. HOBO data loggers were used to measure the air temperature. Thermal properties such as thermal transmittance, thermal capacity, thermal time lag, and solar factor were estimated for each envelope component. The absorptance of the external surfaces was measured by using a reflectance spectrometer. The assessment was performed by correlating average of minimum, mean and maximum air temperatures with the thermal properties. The main conclusion is that increasing thermal time lag and therefore thermal capacity, and decreasing absorptance, thermal transmittance and solar factor of the envelope components helps to improve the thermal performance of naturally-ventilated houses under the climatic conditions of Itaberá. Keywords: thermal performance, thermal properties, naturally-ventilated houses, Brazil

1. INTRODUCTION

3. LOCATION AND AIR TEMPERATURE

Thermal performance of buildings has been a matter of concern in many countries. It is well-known that the better the thermal performance of a building the better the thermal comfort of users and the lower the energy consumption to keep comfort temperature levels. Thus, thermal performance of buildings have been studied in India [1], [2], in Brazil [3], [4], [5], [6], in Israel [7], in Zambia [8], in Japan [9], in Canada [10] and many other countries. Thermal performance of vernacular [11], [12], [13] and historical buildings [14] has also been studied. There have also been some more specific studies, such as the effect of passive cooling on indoor air temperature [15], [16], the importance of roof [17], [18], of colour of the external surfaces [18], [19], of inertia of external walls [20] on the thermal performance of buildings, as well as mathematical modelling for predicting the performance of roofs in the warm humid tropics [21]. The effect of natural ventilation on the thermal performance of buildings has also been studied in different countries [22], [23], [24], [25], [26], [27]. Thus, this study contributes to improving the knowledge about thermal performance of buildings by assessing the influence of thermal properties of envelope components on the thermal performance of naturally-ventilated and occupied houses in Brazil.

Brazil is located between the latitudes 5o north o and 34 south. Fig. 1 shows the map of Brazil with location of Itaberá. Fig. 2 presents the average air temperature variation along the year for ten cities in Brazil. It can be observed that there is a great variation in temperature according to the location of the city. Recife, for example, has average o temperatures ranging from 24.1 to 27.3 C over the o year and Curitiba, from 12.6 to 20.2 C. The cities of Natal, Recife, Maceió and Salvador present annual amplitudes ranging from 3.1 to 3.4oC indicating little difference between summer and winter. For the other five cities, the annual amplitude ranges from 4.3 to o 7.6 C. The annual amplitude for the city of Itaberá is o 7.2 C.

2. OBJECTIVE The main objective of this paper is to assess the influence of thermal properties of envelope components on the thermal performance of naturallyventilated houses located in the city of Itaberá, southeastern Brazil.

4. METHODOLOGY 4.1. The houses The research was performed in five houses located in the city of Itaberá, state of São Paulo. Houses 1-4 are very close to each other and house 5 is 2.7km away from house 1. Amongst all houses, 29 rooms were selected for analysis. Construction details for the rooms selected for monitoring were obtained by performing some measurements and by asking the owners. This was done in January 2006. The dimensions of all rooms, as well as wall thickness and ventilation area were measured on site. Types of walls and roofs were informed by the owners so that their thermal properties could be estimated.

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Each data logger was installed in the centre of each room at 1.70m from floor level. The data loggers were attached to a nylon thread that was stuck on the ceiling. The data logger placed outside house 2 was protected from solar radiation and rain. In order to avoid errors due to different response from each data logger, they were calibrated. All data loggers were programmed to register air temperature every fifteen minutes over a 24-hour period and were placed in a polystyrene box for 24 hours. The data were downloaded into a computer and average figures were calculated. Results from one data logger were taken as reference figures and eventual discrepancies for the other data loggers were then considered when processing the data obtained during the monitoring. 4.4. Absorptance and reflectance of external surfaces The reflectance of external surfaces were measured by using an ALTA II Reflectance Spectrometer. In order to obtain reflectances by using this equipment, measurements have to be obtained both directly from the surface and by covering the surface with white paper. The reflectance considered for the white paper was 90% and the reflectance of the surface can be obtained by using Eq. (1).

Figure 1: Map of Brazil with location of Itaberá.

Air temperature ( oC)

28 26 24 22 20 18 16 14

 = (Ec . 90)/Ep Dec

Oct

Nov

Sep

Jul

Aug

Jun

May

Apr

Mar

Feb

Jan

12 Month Natal

Recif e

Maceió

Salv ador

Brasília

Vitória

Rio de Janeiro

São Paulo

Curitiba

Itaberá

 

Figure 2: Average air temperature for ten cities in Brazil.

The solar orientation of the houses was obtained on the 27 December 2005 by using a compass. Magnetic north was converted to true north by using the Magnetic Declination computer programme. Input data for this programme were latitude (23°51’43” south) and longitude (49°08’14” west) for Itaberá, and the date the solar orientation was obtained. Thus the angle to convert from magnetic to true north was –18°28’51”. 4.2. The monitoring period Air temperature was measured over 41 days, from 26 December 2005 to 4 February 2006. All houses were occupied by their dwellers over this period. 4.3. Equipment Air temperature was registered simultaneously in the 29 rooms and outside house 2. Such data were registered by HOBO portable data loggers. The data loggers were programmed by using the computer programme Boxcar Pro 4-Onset. The same programme was used to download the data to a computer. The data were registered every fifteen minutes over the 41-day period.

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BUILDING PHYSIC (HYGROTHERMIC AND ACOUSTIC)

Eq. (1)

where ρ is the reflectance of the surface (%), Ec is the illuminance reflected by the surface (lux), Ep is the illuminance reflected by the white paper (lux), and 90 is the reflectance assumed for the white paper (%). This method was applied on site and eleven sets of measurements were performed for each surface. The reflectance of each surface was obtained by calculating an average for the eleven values. The absorptances were then calculated by using Eq. (2).  = 100 - 

Eq. (2)

where α is the absorptance of the surface (%), and ρ is the reflectance of the surface (%). 4.5. Thermal properties of envelope components Thermal transmittance (U-value), thermal capacity, thermal time lag and solar factor of all envelope components were estimated following the procedure presented by the Brazilian standard NBR 15220-2 [28]. As all rooms have different roof, wall and window areas, weighted averages were performed in order to obtain an average absorptance, thermal transmittance, thermal capacity, thermal time lag and solar factor for each room. 4.6. Data analysis Data were analysed by verifying the correlation between temperature and thermal properties of the envelope components. Six possibilities for temperatures were considered, that is:

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Average of minimum daily internal temperature for each room; Average of mean daily internal temperature for each room; Average of maximum daily internal temperature for each room; Average of daily difference between minimum external and minimum internal temperatures for each room; Average of daily difference between mean external and mean internal temperatures for each room; Average of daily difference between maximum external and maximum internal temperatures for each room. Each of these six temperature cases were correlated to five variables as shown below: (1) Absorptance of external surfaces; (2) Thermal transmittance; (3) Thermal capacity; (4) Thermal time lag; (5) Solar factor.

capacity and thermal time lag of the envelope components on the internal air temperatures. Average of daily internal temperatures and average of daily differences between external and internal temperatures for each room are shown in Table 2. Such temperatures were correlated with thermal properties of the envelope of the houses. It can be seen that mean temperatures ranged from o o 25.31 C (in house 3) to 27.40 C (in house 3). By analysing the average of daily differences between external and internal temperatures, it can be noticed that all rooms in house 3 and some rooms in houses 2 and 4 have maximum internal temperatures lower than the external ones (positive figures).

 

Table 1: Weighted average for the thermal properties of the components for the monitored rooms. House Room Living 1

Solar factor for walls, roofs, doors and windows with venetian blinds was estimated by using Eq. (3). For windows composed of single glass panes, their solar factor was obtained from the literature. FSo = 100.U..Rse

Eq. (3)

2

where FSo is the solar factor of opaque components (%), U is the thermal transmittance of the component (W/m².K), α is the absorptance of the external surface of the component (non-dimensional), Rse is the thermal resistance of the external surface of the component (m².K/W). 5.

RESULTS

This section presents the results obtained and also the correlations performed to assess the influence of thermal properties of envelope components on the thermal performance of houses located in the city of Itaberá. Table 1 shows the weighted average for the thermal properties of the components for the monitored rooms.

3

4

 

5.1. Measured air temperatures Fig. 3 shows, as an example, daily maximum, average and minimum air temperatures for the six rooms in house 3 as well as the outside temperature. It can be observed that external air temperatures ranged from about 17-32oC over the period. As for the internal air temperatures, they ranged from 2133oC. In general, maximum internal air temperatures were lower than outside temperatures in most rooms. As for the average and minimum internal temperatures, they were higher than the external temperatures all over the period. It can also be noticed that over hot days, although the external air temperature drops to about 21-23oC, internal air temperature ranges from 25o 28 C. This indicates the influence of the thermal

5

Abs. TT TC TTL SF (%) (W/m².K) (kJ/m².K) (hours) (%) 44 2.79 161 2.76 4.63

Dining

50

2.62

130

2.45

5.08

Bedroom 1

43

2.82

165

2.80

4.68

Bedroom 3

50

2.61

129

2.43

5.38

Living

48

1.84

157

4.35

3.34

Bedroom 1

45

1.54

130

4.77

2.65

Bedroom 3

42

1.73

137

4.52

2.74

Bedroom 2

41

1.74

138

4.51

2.74

TV room 1

45

1.69

146

4.42

2.66

Office

41

1.76

139

4.47

2.63

TV room 2

49

2.13

77

2.09

3.84

Living

51

2.01

136

3.83

3.75

TV room

39

1.49

128

3.76

3.01

Bedroom 1

34

1.69

136

3.83

2.79

Bedroom 2

35

1.68

135

3.83

2.81

Bedroom 3

40

1.46

127

3.75

3.19

Living 2

24

2.10

152

4.00

1.91

TV 1

28

2.10

152

4.00

2.27

Living

40

2.14

168

3.99

3.35

Bedroom 1

38

2.05

144

3.86

3.06

Bedroom 2

37

2.01

132

3.80

3.57

TV room 2

38

2.00

131

3.79

3.45

Bedroom 3

35

2.03

136

3.84

3.09

Bedroom 3

59

2.17

112

2.72

5.10

Bedroom 2

64

2.14

98

2.46

5.56

Bedroom 1

56

2.16

150

3.67

4.93

Living

63

2.14

100

2.49

4.75

Bedroom 4

84

2.00

32

1.30

6.70

Dining

59

2.14

146

3.66

4.74

Note: Abs stands for absorptance, TT stands for thermal transmittance, TC for thermal capacity, TTL for thermal time lag, and SF for solar factor.

BUILDING PHYSIC (HYGROTHERMIC AND ACOUSTIC)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Air temperature (oC)

33 Living

29

appropriate to improve the thermal performance of the houses.

 

TV room Bedroom 1

25

Bedroom 2 Bedroom 3

Table 2: Average air temperatures obtained for each room.

21

24.09 26.48 29.32 -2.98

-1.99

-0.83

Bedroom 1 23.87 26.43 29.28 -2.76

-1.94

-0.79

Bedroom 3 24.49 26.74 29.91 -3.37

-2.24

-1.43

Living

24.49 25.78 27.17 -3.38

-1.28

1.32

Bedroom 1 25.45 26.57 27.94 -4.33

-2.07

0.54

Bedroom

HouseRoom

4/2/06

2/2/06

31/1/06

29/1/06

27/1/06

25/1/06

23/1/06

21/1/06

19/1/06

17/1/06

15/1/06

9/1/06

13/1/06

7/1/06

11/1/06

5/1/06

3/1/06

1/1/06

30/12/05

28/12/05

26/12/05

Date (day/month/year)

(a) Daily maximum 1

33

Air temperature ( oC)

Dining

Outside

17

Living

29

TV room Bedroom 1

25

Bedroom 2 Bedroom 3 Living 2

21

Outside

2

4/2/06

2/2/06

31/1/06

29/1/06

27/1/06

25/1/06

23/1/06

21/1/06

19/1/06

17/1/06

15/1/06

13/1/06

11/1/06

9/1/06

7/1/06

5/1/06

3/1/06

1/1/06

30/12/05

28/12/05

26/12/05

17

Date (day/month/year)

(b) Daily average 33

Air temperature (oC)

Living

Average daily difference between external and internal temperatures (°C) Min Mean Max Min Mean Max 24.20 26.35 28.58 -3.08 -1.85 -0.09

Living 2

Living

29

TV room Bedroom 1

25

Bedroom 2 Bedroom 3

3

Living 2

21

Outside

4/2/06

2/2/06

31/1/06

29/1/06

27/1/06

25/1/06

23/1/06

21/1/06

19/1/06

17/1/06

15/1/06

13/1/06

11/1/06

9/1/06

7/1/06

5/1/06

3/1/06

1/1/06

30/12/05

28/12/05

26/12/05

17

Date (day/month/year)

(c) Daily minimum Figure 3: Daily air temperatures in house 3.

4

5.2. Correlations between thermal properties and average internal air temperature

25.14 26.44 27.80 -4.02

-1.94

0.69

Bedroom 2 24.60 26.01 27.48 -3.48

-1.51

1.01

TV room 1 25.20 26.59 27.87 -4.09

-2.10

0.62

Office

25.44 27.02 28.70 -4.32

-2.52

-0.22

TV room 2 24.00 26.22 29.12 -2.88

-1.72

-0.63

Living

24.33 26.06 27.79 -3.22

-1.56

0.69

TV room

24.97 26.47 27.81 -3.86

-1.97

0.68

Bedroom 1 24.12 26.11 28.17 -3.00

-1.61

0.32

Bedroom 2 24.26 26.01 27.76 -3.14

-1.52

0.73

Bedroom 3 24.61 26.11 27.65 -3.49

-1.61

0.84

Living 2

-0.81

1.52

5

23.67 25.75 28.27 -2.55

-1.25

0.21

Living

24.35 26.11 28.09 -3.23

-1.61

0.39

Bedroom 1 24.09 26.19 28.62 -2.98

-1.69

-0.13

Bedroom 2 24.92 26.26 27.63 -3.81

-1.76

0.86

TV room 2 24.34 26.28 29.14 -3.22

-1.78

-0.65

24.13 26.39 28.80 -2.92

-1.78

-0.18

Bedroom 3 23.64 26.62 29.63 -2.52

-2.12

-1.14

Bedroom 2 24.06 26.73 29.38 -2.95

-2.24

-0.90

Bedroom 1 23.82 26.80 29.98 -2.71

-2.31

-1.49

Living

25.22 27.11 29.29 -4.07

-2.61

-0.80

Bedroom 4 25.68 27.15 28.70 -4.63

-2.66

-0.21

Dining 24.81 27.40 30.17 -3.69 -2.90 -1.68 Note: Negative figures indicate that internal air temperature in the room is higher than the external air temperature. 31 30 29 28 y = 0.0387x + 26.751 R2 = 0.2856

27 26 20

5.3. Summary of results Table 3 shows the coefficient of determination for all correlations. By analysing these coefficients it is possible to identify the strategies that can be more

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BUILDING PHYSIC (HYGROTHERMIC AND ACOUSTIC)

24.03 25.31 26.97 -2.92

TV 1

Bedroom

Air temperature (°C)

Figures 4-8 show the correlation between maximum average internal air temperature and some properties for the five houses. Correlations are weak as the coefficient of determination (R2) ranges from 0.0530 to 0.5046. From Figures 4-8, it can be observed that correlations with solar factor are stronger, which indicates that maximum internal air temperatures are dependent on solar factor. The second best correlation is due to thermal time lag, and the third, to thermal transmittance. As solar factor and thermal transmittance increase, internal air temperatures also increase, which may cause thermal discomfort over summer. Thus the thermal performance of such houses, and as a consequence the thermal comfort of their occupants, would improve by decreasing solar factor and thermal transmittance and increasing thermal time lag.

Average daily internal temperature (°C)

30

40

50

60

70

80

90

Absorptance (%)

Figure 4: Correlation between maximum average internal temperature and absorptance.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

transmittance of external components, and increasing thermal time lag. Therefore, the strategies more adequate to improve the thermal performance of the houses along the year are to decrease solar factor by decreasing absorptance and/or thermal transmittance of the envelope components, and increase thermal time lag.

Air temperature (°C)

31 y = 1.4391x + 25.602 R2 = 0.3330

30 29 28 27 26 1

3

2

2

Table 3: Coefficients of determination (R ) obtained from the correlations.

Thermal transmittance (W/m².K)

Figure 5: Correlation between maximum average internal temperature and thermal transmittance.

Air temperature (°C)

31

Properties

30 29

Min Mean Max Min

28 y = -0.0073x + 29.479 R2 = 0.0530

27 26 20

70

120

170

Thermal capacity (KJ/m².K)

Figure 6: Correlation between maximum average internal temperature and thermal capacity.

Air temperature (°C)

31 30 29 28 y = -0.5964x + 30.619 R2 = 0.3406

27 26 1

2

3

4

5

Thermal time lag (hours)

Figure 7: Correlation between maximum average internal temperature and thermal time lag. 31 Air temperature (°C)

2

R for correlations 2 R for with average daily correlations with difference between average daily external and internal internal temperature temperatures Mean Max

Thermal transmittance 0.22 0.02 0.33 0.21

0.02

0.33

Thermal capacity

0.11 0.17 0.05 0.11

0.17

0.05

Thermal time lag

0.02 0.16 0.34 0.02

0.16

0.34

Absorptance

0.09 0.54 0.29 0.10

0.55

0.29

Solar factor

0.00 0.41 0.50 0.00

0.41

0.51

Equations for the best-fit straight lines were obtained from correlations with average minimum, mean and maximum daily internal temperatures. From such equations, the internal temperature differences for the range of thermal properties observed on site could be estimated as shown in Table 4. For example, by reducing the solar factor from 6.70% to 1.91% (maximum and minimum solar factors observed on site), the maximum air temperature in the rooms would be reduced in o 2.54 C. Therefore, an easy solution to improve the thermal performance of such houses would be the reduction of the solar factor by painting the external surfaces with low absorptance colours.

 

Table 4: Internal temperature range obtained by using the interval value of thermal properties observed on site.

30 29

Properties

28 y = 0.5312x + 26.533 R2 = 0.5046

27 26 1

3

5

7

Solar factor (%)

Figure 8: Correlation between maximum average internal temperature and solar factor.

In order to increase minimum air temperature in the rooms, the thermal transmittance of the envelope components should be reduced. On the other hand, absorptance and solar factor should be reduced in order to decrease mean air temperature. Over the summer, the thermal performance of the houses can be improved by reducing absorptance of external surfaces, solar factor and thermal

Interval observed on site

Internal temperature o range ( C) Minimum Mean Maximum

Thermal transmittance Thermal capacity Thermal time lag Absorptance

24-84%

0.84

1.65

2.32

Solar factor

1.91-6.70%

0.06

1.18

2.54

2

1.46-2.82 W/m K

1.01

0.24

1.96

32-168 kJ/m K

0.90

0.92

0.99

1.30-4.77 hours

0.34

0.72

2.07

2

6. CONCLUSIONS The following are the major findings from the analysis shown herein: (1) The methodology presented can be applied to evaluate the influence of the thermal properties of the envelope components on the thermal performance of houses.

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(2) The influence of the thermal properties of the envelope components on the internal air temperatures is not very strong (the highest coefficient of determination obtained from the analysis was 0.55). (3) Although the correlations were weak, it was observed that maximum and mean air temperatures could be reduced by decreasing solar factor and increasing thermal time lag of the envelope components. The solar factor can be reduced by reducing absorptance of the external surface and/or the thermal transmittance of the component. And minimum air temperatures could be increased by reducing thermal transmittance. (4) Absorptance and thermal transmittance together, i.e., solar factor, affect the maximum air temperature in the rooms more than each one separately. (5) An easy way of improving the thermal performance of the five houses, or any other house in Itaberá or under similar climatic conditions, would be the painting of the external surfaces of the envelope components with low absorptance colours. Finally, it is important to mention that correlations between temperature and parameters other than thermal properties were investigated. Some of these parameters were solar orientation, ventilation area, façade area, and roof area. All correlations were weak and not presented herein due to limitation of space.

7. REFERENCES [1] A. Chel and G.N. Tiwari, Thermal performance and embodied energy analysis of a passive house – Case study of vault roof mud-house in India, Applied Energy 86(10) (2009), pp. 1956-1969.

[2]

R.K. Jha, G.N. Tiwari, H.P. Garg and Z.H. Zaidi Thermal evaluation of a “Winter House”, Energy Conversion and Management 32(6) (1991), pp. 555-563.

[3]

G. Grigoletti, M.A. Sattler and A. Morello, Analysis of the thermal behaviour of a low cost, single-family, more sustainable house in Porto Alegre, Brazil, Energy and Buildings 40(10) (2008), pp. 1961-1971.

[4]

[5]

[6]

[7]

[8]

[9]

E. Ghisi and R.F. Massignani, Thermal performance of bedrooms in a multi-storey residential building in southern Brazil, Building and Environment 42(2) (2007), pp. 730742. E.L. Krüger and P.H.T. Zannin, Acoustic and thermal field investigation of low-cost dwellings, a case study in Brazil, Applied Acoustics 68(10) (2007), pp. 1213-1223. E. Krüger and B. Givoni, Predicting thermal performance in occupied dwellings, Energy and Buildings 36(3) (2004), pp. 301-307. E. Krüger and B. Givoni, Thermal monitoring and indoor temperature predictions in a passive solar building in an arid environment, Building and Environment 43(11) (2008), pp. 1792-1804. S. Sharples and A. Malama, Thermal performance of traditional housing in the cool season in Zambia, Renewable Energy 8(1-4) (1996), pp. 190-193. H. Yoshino, S. Matsumoto, M. Nagatomo and T. Sakanishi, Five-year measurements of thermal performance for a semi-underground test house, Tunnelling and Underground Space Technology 7(4) (1992), pp. 339-346.

[10] R.W. Besant, R.S. Dumont and G. Schoenau, The Saskatchewan conservation house: Some preliminary

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performance results, Energy and Buildings 2(2) (1979), pp. 163-174. [11] M.K. Singh, S. Mahapatra and S.K. Atreya, Thermal performance study and evaluation of comfort temperatures in vernacular buildings of North-East India, Building and Environment 45(2) (2010), pp. 320-329. [12] L. Borong, T. Gang, W. Peng, S. Ling, Z. Yingxin and Z. Guangkui, Study on the thermal performance of the Chinese traditional vernacular dwellings in Summer, Energy and Buildings 36(1) (2004), pp. 73-79. [13] M.M. Eftekhari, Comparative thermal performance of new and old houses, Energy and Buildings 25(1) (1997), pp. 69-73. [14] R. Cantin, J. Burgholzer, G. Guarracino, B. Moujalled, S. Tamelikecht and B.G. Royet, Field assessment of thermal behaviour of historical dwellings in France, Building and Environment 45(2) (2010), pp. 473-484. [15] B. Givoni, Indoor temperature reduction by passive cooling systems, Solar Energy, In Press, Corrected Proof, Available online 4 November 2009. [16] R. Tenorio, Dual mode cooling house in the warm humid tropics, Solar Energy 73(1) (2002), pp. 43-57. [17] S.A. Al-Sanea, Thermal performance of building roof elements, Building and Environment 37(7) (2002), pp. 665-675. [18] M.T.R. Jayasinghe, R.A. Attalage and A.I. Jayawardena, Roof orientation, roofing materials and roof surface colour: their influence on indoor thermal comfort in warm humid climates, Energy for Sustainable Development 7(1) (2003), pp. 16-27. [19] N.K. Bansal, S.N. Garg and S. Kothari, Effect of exterior surface colour on the thermal performance of buildings, Building and Environment 27(1) (1992), pp. 31-37. [20] N. Aste, A. Angelotti and M. Buzzetti, The influence of the external walls thermal inertia on the energy performance of well insulated buildings, Energy and Buildings 41(11) (2009), pp. 1181-1187. [21] C. Kabre, A new thermal performance index for dwelling roofs in the warm humid tropics, Building and Environment 45(3) (2010), pp. 727-738. [22] N.A. Al-Hemiddi and K.A.M. Al-Saud, The effect of a ventilated interior courtyard on the thermal performance of a house in a hot–arid region, Renewable Energy 24(3-4) (2001), pp. 581-595. [23] C. Simonson, Energy consumption and ventilation performance of a naturally ventilated ecological house in a cold climate, Energy and Buildings 37(1) (2005), pp. 2335. [24] G. Makaka, E.L. Meyer and M. McPherson, Thermal behaviour and ventilation efficiency of a low-cost passive solar energy efficient house, Renewable Energy 33(9) (2008), pp. 1959-1973. [25] M.-H. Kim and J.-H. Hwang, Performance prediction of a hybrid ventilation system in an apartment house, Energy and Buildings 41(6) (2009), pp. 579-586. [26] T.J. Kim and J.S. Park, Natural ventilation with traditional Korean opening in contemporary house, Building and Environment 45(1) (2010), pp. 51-57. [27] R. Tang, I.A. Meir and T. Wu, Thermal performance of non air-conditioned buildings with vaulted roofs in comparison with flat roofs, Building and Environment 41(3) (2006), pp. 268-276. [28] ABNT (Associação Brasileira de Normas Técnicas). NBR 15220-2, Desempenho Térmico de Edificações - Parte 2: Métodos de Cálculo da Transmitância Térmica, da Capacidade Térmica, do Atraso Térmico e do Fator Solar de Elementos e Componentes de Edificações [Thermal performance of buildings – Part 2: Method to calculate thermal transmittance, thermal capacity, thermal time lag and solar factor of elements and components of buildings], Rio de Janeiro-RJ, 2005 (in Portuguese).

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Effect of two exterior louver systems on solar transmittance and indoor thermal conditions: Experiment and simulations Abel TABLADA DE LA TORRE1,2, Dirk SAELENS 1, Staf ROELS1 1

2

Division of Building Physics, Department of Civil Engineering, K.U.Leuven, Belgium Department of Research, Direction of Architecture and Urbanism, Office of Havana’s Historian, Cuba

ABSTRACT: The main objective of this study is to compare measured and predicted transmitted solar radiation through a double-glass window with exterior louver systems and the resulting indoor thermal conditions. A vertical and horizontal louver system (both with movable horizontal slats with an elliptical section) were installed at the exterior facade of two well insulated boxes. The exterior global and the transmitted solar radiation and the indoor air temperatures at different locations have been measured in the test set-up and are compared with dynamic simulations by solving the energy balances with a Building Energy Simulation program (EnergyPlus) which includes an algorithm for exterior louvers. The comparison of the experiments and simulations show that solar transmittance is better predicted for horizontal than for vertical louver system. In the case of the vertical system, solar transmittance through slats with an inclination of 45° was better predicted than through open slats. The vertical louver system provides more efficient solar protection than the horizontal louver system. The average deviation between the predicted and measured indoor temperatures was less than 1 K. Keywords: shading devices, solar transmittance, solar radiation, measurements, building energy simulation.

1. INTRODUCTION Exterior shading devices can reduce solar gains inside buildings. Due to the variation of solar position along the year and during the day, the use of movable exterior louvers instead of fixed shading devices can imply an advantage in terms of energy savings and user thermal and daylight comfort. The exact prediction of Total Solar Energy Transmittance (TSET: sum of the short-ware transmittance and the secondary heat flux due to the heating of the shading and glazing systems) through louver systems is very complicated and most of the time, simplified. Common simplifications in the calculation of TSET are the assumption of slats as flat or without thickness. Also, specular and diffuse reflections are limited and the effect of the secondary heat flux from the louver system towards the glazing facade is often neglected. Experiments on glazing facades with exterior blinds have been performed both at laboratory test facilities [1] and on actual facades in outdoor test [2] in order to obtain TSET values and to validate analytical and numerical models. However, apart from the different slat-shape used on these experiments (blinds vs. elliptical louver in this study), no comparison was made between different shading systems, e.g. vertical vs. horizontal systems. In order to measure and predict short-wave radiation and the secondary heat gain on facades with exterior louvers, laboratory experiments and Computational Fluid Dynamics simulations [3] have been performed as part of a larger research. In addition, simulations have been performed using two Building Energy Simulation (BES) programs in order to propose passive design strategies on an apartment block using exterior louvers [4].

Incorporating the response to actual and fluctuating weather conditions is a prerequisite for a complete evaluation of thermal conditions inside actual buildings. Therefore, a test set-up with two separated insulated boxes inside the Vliet-test building was constructed having a glass facade oriented towards the south-west. Measurements were performed first without shading devices and then with exterior louver systems during two periods with a duration of three weeks each. In this paper, the measured transmitted global solar radiation (short-wave transmittance) and the resulting indoor thermal conditions reported in [5] are compared against dynamic simulations by solving the energy balances with a BES program (EnergyPlus).

2. METHODS 2.1. Experimental set-up Two shading systems are installed at the exterior of two well insulated boxes which have a double2 glass window of 1.2 x 1.2 m (see fig. 1 and 2). A vertical and horizontal louver system (both with movable horizontal slats) were installed on box 1 and box 2 respectively after measuring several parameters without the shading devices. The boxes were constructed inside a test building at the Campus Arenberg of the Katholieke Universiteit Leuven in Belgium (50.9° N, 4.7° E). Table 1 gives an overview of the construction of the boxes. The walls are made up of strongly insulating sandwich panels with 16 cm XPS and plywood on both sides. The windows are highly insulated due to an argon filling and a low-emissivity foil inside the cavity. The plywood surfaces inside the

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

boxes were painted in black to achieve the maximum absorption of incident solar radiation.

Box 2

Box 1

device. More details on the set-up description is explained in [5]. The pyranometer inside each of the boxes is placed on the central axis at 30cm from the bottom of the window and separated 3 cm from the glass pane. A third, reference, pyranometer is placed outside the boxes on a vertical position at the same facade facing south-west as can be seen in figure 1-top. The pyranometers are able to measure the solar radiation in the spectral band of 310 to 2800 nm with 2% of daily uncertainty. The transmitted solar radiation (vertical plane) and interior air temperature during two periods were analyzed by comparing measured and predicted values by a BES program (EnergyPlus). Each period had a duration of 20 days. During the first period st th from August 21 till September 9 the slats were completely opened, thus the slats on the vertical and horizontal system are parallel and perpendicular respectively with respect to the ground as can be seen in figure 1-top. These positions will be further referred as 'open' for both louver systems. During the rd th second period from September 23 till October 12 both louver systems had the slats at 45° with respect to the ground. In this position the upper side of the slats is facing the sky and the exterior environment as shown in figure 1-bottom.

Figure 1: Top: location of louver systems (open position) at each box facing southwest at the test building, bottom: interior of box 1 with slats at an inclination of 45 degrees. Table 1: Wall properties.

Floor

Area m² 1.24

U W/(m²K) 0.276

Ceiling

1.24

0.211

Outer-side wall

1.72

0.33

Inner-side wall

1.72

0.317

Material name and position

Back wall

2.21

0.207

Outside panel above window

0.58

0.284

Figure 2 shows a section of box 2 with the location of the measurement equipment inside and outside the test set-up. The width, depth and height 3 equal to 1.23 x 1.0 x 1.67 m respectively. Each box and its corresponding louver system are equipped with 48 thermocouples, 1 pyranometer and 1 anemometer. To eliminate radiative effects, the thermocouples are shielded with aluminium tape. Box 1 has identical geometry and instrument position, but is equipped with a vertical shading

2

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Figure 2: Section of the set-up on Box 2 at the test building (VLIET) with main dimensions and location of measurement instruments. Width = 1.23m, depth = 1.0m.

The optical properties of the aluminium slats and of each layer of the glass were obtained from laboratory measurements [6]. The aluminium slats have a high solar reflectance (67 %) from which 6 % is specular. This feature, together with the curved surface, has an important effect on the solar radiation transmittance towards the interior. The values of solar transmittance fraction (τ) can be seen

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

0.585

2.2. Building Energy Simulation program The Building Energy Simulation (BES) program used to solve the energy balances is EnergyPlus [7]. The program uses an algorithm to calculate vertical systems of louvers and blinds. The geometry of the louvers (flat only) and separation from the facade are inputs. It also takes into account heat and mass transfer from the slats to the glass facade. The program uses a simplified raytracing method to calculate direct and diffuse beam reflections between the slats and towards the glazing but only a single value of reflection coefficient can be given for diffuse and specular reflection. In addition, the sky is considered isotropic when shadings are present. On the other hand, for the horizontal system the program does not have such an algorithm, thus each slat is considered as an independent shading object with no heat emission. For external shading the program calculates direct and diffuse radiation passing through the slats. The coordinates of each slat at open and inclined position are therefore inserted.

3. RESULTS 3.1. Measured solar transmittance First we describe the measured transmitted global radiation inside each box and the measured incident global radiation on the facade oriented southwest for two sunny days representing each measurement period. These are plotted in figure 3 and 4. For the first period with the stats open, on box 1 (vertical louver system) the solar transmittance is mainly the result of diffuse radiation. Only in the afternoon direct sunrays penetrate twice in between the slats. On box 2 (horizontal louver system), there are intermittent direct sunrays at noon when the sun is at high position and the slats are on vertical (open) position which produce a thin shade. Then, in the afternoon, with the sun at lower positions, the horizontal louver system acts as an opaque overhang. 900

2.3. Weather data

700 600 W/m 2

direct τ through slats

500 400 300 200 100 0 7:00

Hourly data from the station outside the test building are used as a weather file. These include, air temperature, relative humidity, wind speed and direction, and global radiation on a horizontal surface. The values of direct beam and diffuse radiation are also needed in the BES program but they where not measured on the site. Therefore, this data was partially provided by the Belgian Building Research Institute (BBRI) which is in the outskirts of Brussels. At BBRI only the global (Rgl) and diffuse (Rdiff) radiation on a horizontal surface is measured, but with this data the value of the direct radiation (Rdir) can be calculated as shown below. Subscripts b represents values from BBRI and v from the VLIET test building.

800

31 Aug. Slats open

Box 1

Box 2

18:00

0.585

0.75

17:00

0.72

BES - Box2 (horiz)

16:00

BES - Box1 (vert)

The measured value of Rgl_v, together with the calculated Rbeam_v and Rdiff_v are used in the EnergyPlus weather file. This method proved to be more accurate for validation purposes than other conversion methods using the global radiation, air temperature and relative humidity as input.

15:00

0.585

14:00

0.598

0.79

α = sun altitude

13:00

0.8

BES – No shading

Rbeam_v = Rdir_v / cos (α)

12:00

Measured at Lab

EnergyPlus uses the value of beam radiation (Rbeam) instead of Rdir on a horizontal surface. Therefore, according to the sun altitude we obtain Rbeam as follows:

11:00

τ int. low-e glass (-)

r = Rdir_b / Rgl_b Rdir_v = r * Rgl_v Rdiff_v = Rgl_v - Rdir_v

10:00

τ ext. clear glass (-)

With a ratio (r) of Rdir_b with respect to Rgl_b at the BBRI site the Rdir_v at VLIET building is calculated from Rgl_v. Then, the diffuse radiation is obtained from the subtraction of Rdir_v from Rgl_v. The procedure is shown below:

9:00

Table 2: Solar transmittance fraction (τ) measured at a laboratory and input values at BES for each box considering dirtiness/dust on the glazing surfaces.

Rdir_b = Rgl_b - Rdiff_b

8:00

in table 2 for the exterior clear and interior low emissivity glass. These original values were adapted as input at BES in order to take into account glass dirtiness and dust accumulation. Separated measurements at different positions and glass dirtiness were performed on both boxes to get approximated values of τ, first without shading systems, and then, after the installation of the vertical and horizontal louver system. In box 1, the reduction of solar transmittance is higher than in box 2 due to the vertical louver system which enhances more dust accumulation over the glass surface than in box 2 with the horizontal louver system. The interior glass pane dirtiness is also considered.

Reference

Figure 3: Incident and transmitted radiation on a sunny day in August corresponding to period 1 of measurements with the slats in open position.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

For the second period with slats at 45 degrees, there is no direct radiation inside box 1; therefore the solar transmittance is only the result of diffuse and reflected radiation. On box 2 the solar transmittance is similar to the one on period 1, but due to the lower position of the sun in the afternoon (27/Sept. instead of 31/Aug), the direct transmittance is produced earlier in comparison with the first period. At noon, the slats at 45° do not allow any solar transmittance as in the case with slats open. However, before noon with sunrays almost parallel to the southwest facade, there is still incident solar radiation at the lower and left part of the window due to the limited lateral extension of the horizontal system (0.44 m on each side of the window).

(reference) and transmitted radiation into each box per day for the measuring campaign without shading devices. As can be seen, the first source of error is the calculated value of incident radiation on the facade (2.8% lower than the measured one). In addition, the predicted values of transmitted radiation were also smaller than the measured ones with an error of 7.3 % and 6.4 % for box 1 and 2 respectively.

900 800 700

W/m

2

600 500 400 300 200 100

27 sept. Slats at 45°

Box 1

Box 2

18:00

17:00

16:00

15:00

14:00

13:00

12:00

11:00

10:00

9:00

8:00

7:00

0

Reference

Figure 4: Incident and transmitted radiation on a sunny day in September corresponding to period 2 of measurements with the slats at an inclination of 45°.

3.2. Measured vs. predicted solar transmittance In order to compare both measured and predicted solar transmittance the radiation values have to be adjusted to represent the average transmitted radiation per square meter. Since the pyranometer measures global radiation at a single point, several measurements were performed at different positions behind the glass in order to obtain a correlation of transmission values in function of height. From that correlation a constant coefficient for each box was obtained to be multiplied by the integral value measured at 30 cm height from the bottom of the glass. In Box 1 with exterior vertical louver system, the coefficient was 1.03 due to the larger solar transmittance on the top of the window. On box 2 with the horizontal louver system, the coefficient was 0.72 due to the gradually smaller solar transmittance from the bottom to the top of the window. On the other hand, in EnergyPlus, the outputs of total solar transmittance (W) through the window were divided 2 by the area of the glass (1.25 m ) to obtain an 2 equivalent W/m . Before and after the installation of the shading devices, the solar transmittance was determined. Solar transmittance and thermal conditions were practically the same on the two boxes. In that way, differences on thermal conditions once the shading was installed could be attributed to the type of louver system. The same conditions were simulated and then compared with the measured values. Figure 5 shows the average incident radiation on the facade

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Figure 5: Average incident on facade (reference) and transmitted radiation on each box per day without shading devices.

The results from the periods with shading are summarised in figure 6. The bars indicate the average per day of total transmitted radiation in KWh per squared metre. The predictions of transmitted radiation on box 2 with a horizontal louver system were closer to the measured values than for box 1 with a vertical louver system. The deviations for box 1 were -12 % and +30 % for open and slats at 45 degrees respectively. However, the total difference is 2 higher on open slats (-70 Wh/m .day) having larger thermal impact than the case with slats at 45 2 degrees (+26 Wh/m .day) where there is only diffuse and reflected transmittance. For box 2 the deviations were around +4 % and almost zero for open and slats at 45° respectively. On box 2, there is a better agreement on period 2 when the slats are at 45°, which means the horizontal louver system performs similarly to a typical opaque overhang. For the open 2 slats the program predicts 26 Wh/m .day less transmitted radiation than the measured value. Figure 7 compares the measured and calculated transmitted percentage of solar radiation in relation to the incident radiation on the facade. In that way only the error due to the shading and glass transmittance are considered and not the error (-2.8 %) due to the predicted radiation on the facade or due to the calculated beam and diffuse radiation for the weather file. In terms of the slat position, for box 1, EnergyPlus predicts a relatively closer value when slats are open than with an inclination of 45 degrees. For the case of slats at 45 degrees, the large deviation shown in figure 6 is reduced. On the other hand, on box 2, the differences with respect to the measured values are smaller than the case with vertical louver system. The relative transmittance with respect to the incident radiation on the facade is almost the same as the measured values.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

deviation of 0.8 K. With slats at an inclination of 45 degrees, there is a slightly better agreement between measured and predicted air temperatures with an average deviation of 0.7K.

Figure 6: Average transmitted solar radiation on each box per day for open slats and with slats at 45°

Figure 8: Measured (Measur) and predicted (BES) average air temperature on box 1 for the two periods (4 days). Only the sequence of hours coincides between the two periods but not the actual days.

Figure 7: Percentage of transmitted solar radiation on each box in relation to reference incident radiation on facade. The reference values are from measurements and BES respectively.

3.3. Measured temperatures Temperatures are evaluated based on average air temperatures inside each box. These averaged temperatures are obtained from thermocouples at the positions shown in figure 2. There is no direct correlation between the measured temperatures and the thermocouple positions. The standard deviation between the measured temperatures at different heights is 0.15 K and 0.1 K for box 1 and 2 respectively. EnergyPlus, on the other hand, gives a single value for each thermal zone. In figure 8 and 9, the hourly measured and predicted air temperatures during four days are plotted for the two periods for box 1 and 2 respectively. In table 3 the average air temperatures over the whole period are shown for all cases. For box 1 with a vertical louver system (fig. 8) there is, in general, a good agreement when the slats are open and the differences are not directly related to a specific time of the day. When the slats have an inclination of 45 degrees the predicted values are somehow higher than the measured ones during the daytime while during the night they are lower, above all, after cloudy days. The average deviation is, however, only +0.2 K. For box 2 with a horizontal louver system (fig. 9) the predicted temperatures are higher than the measured ones, above all for the case with open slats during the night. This produces an average

Figure 9: Measured (Measur) and predicted (BES) average air temperature on box 2 for the two periods (4 days). Only the sequence of hours coincides between the two periods but not the actual days. Table 3: Measured (Measur) and predicted (BES) average air temperature on box 1 (vertical louvers) and box 2 (horizontal louvers) for the two periods: open slats and slats at 45º .

Measur (ºC)

BES (ºC)

ΔT (K)

Error (%)

Open B-1

27,3

27,1

-0.2

0.5

Open B-2

27,5

28,3

+0,8

2.9

45° B-1

14,5

14,7

+0,2

1.5

45° B-2

16,2

16,9

+0,7

4.1

4. DISCUSSION Several reasons may have produced the differences between the measured and predicted values by the BES program. A source of error is the different beam radiation implemented in the weather file due to the lack of on-site measurements of direct or diffuse radiation. However, applying this method -

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

explained in section 2.3- for validation purpose provided more accurate results than using existing models to predict direct and diffuse radiation from global radiation values. In order to separate the errors produced by the different beam radiation and by the incident radiation on the facade, the fraction of transmitted radiation was plotted in figure 7. The transmitted radiation deviations can be attributed to both the errors on glass and shading devices transmittance calculation. Therefore, in order to isolate the error due to the shading device the shading transmittance factor on both the measured and predicted cases were obtained by dividing the final solar (short-wave) transmittance when there is shading by the transmittance of the glass only. Table 4 gives the shading transmittance factor for the four cases as a result of measurements and simulations. Table 4: Measured (Measur) and predicted (BES) average solar transmittance due to shading only.

Open slats Measur BES

Slats at 45° Measur BES

Box 1

0.46

0.41

0.13

0.17

Box 2

0.54

0.57

0.56

0.59

However, still these factors are based on the assumed transmittance of the glass that could be slightly different due to the effect of the dust and dirtiness on the glass that change over time and from one position to the other on the glass. The values inserted on the simulation were obtained from several measurements, but only at specific time and at a reduced number of positions behind the glass. One aspect that should be revised is the higher solar transmittance (and shading transmittance factor) on the vertical system when slats are at 45 degrees. Due to the actual multiple reflection between the slats, it was expected that measured values of transmitted solar radiation were higher than the ones predicted by the BES program which only accounts on a limited number of reflections. A possible cause of that 'over-prediction' could be the coefficient used to modify the measured values. The used coefficient (1.03) accounts the influence of height on transmitted radiation but it may be different along the year. In the case of the slats at 45 degrees it was not measured and could be higher due to the much higher difference between the transmittance on top of the louver system than on the bottom in comparison with the case of open slats. The single coefficient to describe in EnergyPlus both the diffuse and the specular reflection on the slats could also contribute to an over-estimation of the reflections between the slats. In addition, the fact that slats can only be modelled as flat planes in EnergyPlus may also produce a higher transmittance due to reflections than the actual case with elliptical slats. Concerning the thermal conditions, the average deviation between the predicted and measured indoor temperatures was less than 1 K. The small errors could be the result of uncertainty on air infiltration, and measured/assumed material properties.

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5. CONCLUSION In this paper measured transmitted global solar radiation and indoor air temperatures are compared against dynamic simulations by solving the energy balances of two test boxes with exterior shading devices with a BES program (EnergyPlus). The solar transmittance was better predicted for the horizontal than for the vertical louver system. In the case of the vertical system, solar transmittance through the slats with an inclination of 45° was better predicted than through open slats. The average deviation between the predicted and measured indoor temperatures was less than 1 K (STDV=1.1) for the two types of shadings and slat position. The vertical louver system provides higher protection from solar radiation than the horizontal one. Measurement errors and modelling limitations may have provoked the differences between measured and predicted transmittance through the louver and glazing system. However, these differences can be considered of minor importance for long term energy analysis. Furthermore, more accurate TSET calculation method will be proposed to be integrated at BES programs and compared with measurements.

6. ACKNOWLEDGEMENTS The authors are grateful to Reynaers Aluminium NV for their financial support. We appreciate the contribution of Erik Rasker, Danny Geysels and technicians from Reynaers Aluminium. Thanks also to Patricia Elsen, Wim Bertels and Paul Verbeek for the technical assistance.

7. REFERENCES [1] T. E. Kuhn, C. Bühler and W. Platzer, Evaluation of overheating protection with sun-shading systems. Solar Energy. (2000) 69, 59-74. [2] H. Simmler and B. Binder, Experimental and numerical determination of the TSET of glazing with venetian blind shading. Building and Environment. (2008), 43 (2), 197-204. [3] A. Tablada, D. Saelens, J. Carmeliet, M. Baelmans, Investigation on airflow and heat transfer of a glazing facade with external louvers. 4th International Building Physics Conference, Istanbul. (2009). [4] A. Tablada, J. Carmeliet, M. Baelmans, D. Saelens, Exterior louvers as a passive cooling strategy in a residential building. 26th International Conference on Passive Low Energy Architecture, Quebec City. (2009). [5] A. Tablada, D. Saelens and S. Roels, Cooling potential of exterior louver systems, REHVA world congress, Antalya, Turkey (2010). [6] G. Flamant, Report: 632xb760, Belgian Building Research Institute, Limelette, Belgium (2009). [7] http://apps1.eere.energy.gov/buildings/energypl us/

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Hygrothermal Performance of Vegetation on Cladding and Translucent Façade Systems Javier ALONSO1, Francesca OLIVIERI1, Javier NEILA1, César BEDOYA1 1

Department of Construction and Technology in Architecture, Technical University of Madrid, Madrid, Spain.

ABSTRACT: This report aims on evaluating architectural greening as a passive cooling technique. Two green wall systems have been installed and monitored continuously during summer period in an experimental building. One of these prototypes consists of a freestanding, cladding enclosure, made with modular pre-vegetated panels, while the other façade is a three layered translucent system, forming an extra-flat greenhouse where a creeper plant grows. The translucent façade can be in order to ventilate the building. Both enclosure prototypes were analyzed simultaneously with and without vegetation, in order to describe the plants effects separately from the hygrothermal performance of each system. After the selection of the most representative monitored days, hygrothermal analysis revealed that vegetation cooling effect was higher on the opaque prototype and also suggested that translucent façade mitigated indoor overheating better when its inner layer was not open. Keywords: Thermal analysis, Energy efficiency, Green wall, Monitoring.

1. INTRODUCTION

2. OBJETIVE

As energy management has become a valuable point lastly, most published studies on architectural greening refer to vegetated roof systems and their thermal performance. Researching [1] and developing of roof gardens [2] and vegetal façades has increased, but designing constructive systems with vegetated elements implies an awareness of plants as constructive elements. Urban greening also assures lower level of CO2 emissions, as well as it offers a thermal response [3] that varies depending on climatic conditions. Hygienic ventilation [6], sound insulation [4], microclimate [5], thermal ventilation and solar protection are improved in dwellings, as mentioned reports point. At Tokyo Institute of Technology [6] Hoyano contrasted thermal performance of an ivy-covered balcony and an unprotected one. Solar irradiation passing across plant-protected window was up to 45% lower. Concerning superficial temperatures, indoor floor remained 14°C cooler behind ivy layer. Also, air temperature remained higher during the night time due to heat loss retention of the vegetated layer. Similar study [7] on blank walls covered by creeper plants thrown even more notable overheating mitigation on vegetated façades. Vegetation on cladding façades has been studied widely [3, 8], and their results found strong associations between the moisture in growth media, vegetation coverage and cooling effect, demonstrating the importance of maintaining a healthy plant cover and a hospitable substrate. It is also remarkable the research reported at TU Delft [9], whose objective was to define the thermal performance of a double skin façade containing creeper plants. A simulation model was developed to analyze heat flows through this enclosure, concluding benefits for indoor climate as overheat mitigation under summer conditions. Also this paper was mentioned assuming a starting point for translucent façades.

This investigation aims on evaluating hygrothermal performance of two green wall systems at a hot-summer climate: cladding vegetated panels and a three layered translucent green wall. The objective includes measuring effects of plants as overheating regulators, and focuses on vegetation influence separately from each green wall system, considering previous studies.

3. MATERIAL AND METHODS An experimental approach was used to assess the hygrothermal effect of vegetation. As in mentioned reports [7-9], the test consisted in contrasting monitoring data from two buildings whose only difference was the plants presence on their enclosure. This research started at the end of 2007 with the installation of four façades in an experimental building in Colmenar Viejo (Madrid, Spain). The constructive systems used included two cladding enclosures and two translucent façades. 3.1. Experimental prototype Each green wall prototype was installed on the South-faced façade of two identical modules (hereinafter M1, M2, M3 and M4), whose other enclosures were thermally insulated so as to be considered adiabatic (Figure 1). Thus, heat gains came through studied façades.

Figure 1: Experimental building partial plan and adiabatic modules M1, M2, M3 and M4.

M1 and M4 modules tested the cladding green wall system. This constructive solution consists of

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modular, pre-vegetated panels filled with substrate, a drip irrigation system, and vertical bearing structure (Figure 2A). Green panels can be taken apart easily through a simple metallic coupling system, although they do not allow air flow between inside and outside as they are sealed together with silicone. Panels of M1 South façade had no vegetation, nor irrigation. As a consequence, substrate in M1 was dry. Cladding panels of M4 were covered with vegetation, and drip irrigation system was active. Since there is no wall or glazing behind the panels, behavioral differences result from the effect of vegetation.

enclosure. Thus, it is possible to estimate insulation and cooling effects from plants and moisture of the substrate by contrasting M1 and M4 monitoring data.

Figure 3: Translucent façade positions

On the other hand, the monitoring of each façade position permitted describing the six translucent wall performances, where ventilation through chamber and the thermal buffer effect varied. It was expected that the system improved hygrothermal indoor conditions during summer, as a consequence of the air flow through the humid vegetal layer. Figure 2: Cladding (A) and Translucent (B) systems

The translucent system was installed in M2 and M3 modules. It consisted of an interior layer with a sliding sash window in two leaves, an intermediate chamber which contained vegetation and a selfirrigation system, and an external layer based on a truss of adjustable polycarbonate slats (Figure 2B). What made the modules enclosure different was a vegetal layer incorporated inside the chamber of M3. In order to respond properly to variable climate and seasonal needs, the façade design permitted six different positions by opening the inner window and adjusting the outer slats (Fig.3). Thus, this feature tries to analyze two expected results: convection effect inside the chamber by opening only upper and lower slats, and ventilation of the indoor environment by opening the sash window. Façade positions 1 and 2 attempted to evaluate the hygrothermal performance of the system without communicating indoor with outdoor environment. Sash window remained opened during all day for façade positions 3 and 4, though. For façade positions 5 and 6, the study included night ventilation by opening the sash window, from 21:00 to 9:00. On the one hand, this experiment was designed to study the thermal influence of vegetation separately from expected isolation effects of the substrate. As in M1 and M4 only the pre-vegetated cladding was considered, monitoring data are not applicable as a real façade, but as a contribution to global performance of a building added to a blank

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3.2. Monitoring description The experimental procedure consisted on registering temperature and relative humidity data in the different layers of each described enclosure. A weather station incorporated to the roof of the experimental building registered data related to horizontal solar radiation, pluviometry, wind speed and outdoor relative humidity. As reported by Eumorfopoulou and & Kontoleon [7], glass mercury thermometers were not used because of their lower sensitivity and precision. Moreover, their study revealed different phase values of manually and automatically observed temperatures. Surface temperature data from each façade component was measured by three-threaded state probes. Four-threaded state probes were used to measure the ambient temperature in each constructive layer. The outdoors probes that could be affected by direct solar radiation were protected by a specially designed box, as it was done in previously mentioned test. In order to assure the accuracy of the measurements in all the cases, the installation of probes was duplicated. This duplicity was also useful for probe failures, and it would not be necessary any reinstallation. Each probe registered data in periods of five minutes. An average was obtained from every three values (15 minutes). Besides, programmable automation equipment transforms the analog signals

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

from probes and flow meters into temperature and flow values. During the 2010 summer, each position of the translucent façade was monitored continuously for two weeks (Table 1). Table 1: Monitoring periods for translucent façade during 2010 summer

Month June July August

Dates 1st to 15th th th 16 to 30 st th 1 to 15 th st 16 to 31 st th 1 to 15 th st 16 to 31

Position FP5 FP6 FP1 FP2 FP3 FP4

3.3. Vegetation Plants selection aimed on incorporating local species to adjust properly to Continental Mediterranean climate that characterized the location where the monitored building was placed. Hot summers and mild winters are the main features regarding this type of climate. As it has been previously demonstrated [8], an adequate plant caring was necessary for this study. Sedum species were chosen for M4 since their characteristics imply a minimal maintenance. Generally, these species constitute herbaceous flowering plants with water-storing leaves that tolerate adverse weather conditions without significant water requirements. The perennial Sedum species selected were Sedum acre (Goldmoss Sedum), Sedum sexangulare (tasteless stonecrop), Sedum sediforme (pale stonecrop), Sedum reflexum (Sedum rupestre). These evergreen species are characterized by a proper plant growth as a ground covering, despite of varying light conditions and limited substrate. Also, these hardy plants have a dense growth. For this reason, it was important to guarantee an accurate percentage of compost in the growing media composition to avoid an invasive development. The substrate, which was placed inside the panels, was wrapped up with a geotextile layer that contributes to its better drainage. Plant placed inside the greenhouse space of M3 was jasminum officinale (jasmine), which grew there during since 2009. As it was noticed by other reports [7, 9] the most gainful choice is to employ deciduous plants, in order to shade the façade in summer, but allowing light and irradiation incoming during the winter. 3.4. Analysis trough days-type Experimental and monitoring setup described in 3.2 generated a great amount of information, which made a previous selection from data necessary to make them legible. In order to analyze vegetation influence on each prototype, and on each translucent façade position separately, this study includes a comparison between daily data from certain days selected among each monitoring period. This method, focused on complete registered days, enables to consider similar exterior conditions and

avoided inaccuracy from daily average values. Also, as described further, particularities from the statistical sample were minimized. Therefore, day-type selection aimed on choosing those days that presented no irregularities or peculiarities to what a statistically representative day would be for each month. The comparison method consisted in contrast data from M1 and M4 separately from M2 and M3, whose only difference was vegetation presence. Also, this day-type analysis leaded to calculate indoor hygrothermal comfort hours behind translucent façade, according to Olgyay research for mild climates. 3.5. Day-type selection method The six positions of the translucent façade obviously determined the number of minimum daystype necessary for a complete analysis. Thus, these six days-type were the same used to evaluate vegetation performance over the cladding façade, in order to contrast the performance of the two systems under equal weather conditions. Selection method for days-type was developed from generation of ISO Test Reference Years (TRYs) procedure [10]. These TRYs are created through monthly averages of temperature, humidity, solar radiation and wind speed values from, at least, last decade. In a similar procedure, a Reference Day was created for each monitoring month, based on hourly averages of last ten years (from 2000 to 2009, both included) [11]. This Reference Day for each month was used to choose each day-type for each position, and from each corresponding monitoring period. Selected days would be those with most similar values registered, contrasted with the Reference Day hour to hour. As for ISO TRYs, temperature, humidity and solar radiation were more relevant features than wind speed. For each monitored day, the procedure consisted on calculating the summation of the absolute value of difference between hourly data from Reference Day of that month. Therefore, each day considered showed a value for each variable, composed by the summation of the difference of each of the 24 hourly values. Then, each day was assigned a rank for each parameter, starting at 1 for the closest value to the corresponding Reference Day (lowest value for absolute difference hour to hour). ΣRank value came from summing the three individual ranks of temperature, solar radiation and relative humidity. The 3 days with lower ΣRank were chosen, because they were the most similar to Reference Day. Finally, from these 3 pre-selected days, the one with lower rank of wind speed was selected as day-type.

4. RESULTS 4.1. Climate trends on summer days-type Monitoring data showed a lower daily average temperature in June than July and August (Figure 5), and July registered highest temperature peak values.

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Solar radiation in June was also irregular due to rainy days.

Table 3: Layer temperature values (ºC) for each module. th

July 28 17:30 - Te = 34.87ºC (daily maximum) Tf / Tsf Tse Tsi Ti M1 60.3 36.6 31.9 M4 38.9 / 39.8 29.9 23.7 24.1 Tss 48.1 45.8

M2 M3

Tc 44.0 37.9

Tsw 43.8 36.9

Ti 36.5 29.8

4.3. M1-M4 differences

Figure 5: Daily values for each day-type

Selected day-type for each position is shown on Table 2. First day-type (FP5) in June presented the lowest solar radiation, and the rest of data suggested a rise from June to August. Indoor and chamber values pointed that temperature increases in July have a higher influence, and both values were mild in June. Table 2: Day-type for each position, during 2010 summer

FP1 July th 5

FP2 July th 28

FP3 August th 4

FP4 August th 24

FP5 June nd 2

FP6 June nd 22

4.2. Temperature gradient Monitoring data showed how temperature values decreased especially across the substrate in M1 and M4, and through the chamber for M2 and M3. Figure 6 and Table 3 present values for the second daytype of July at 17:00, when outdoor ambient temperature was the daily maximum. It is remarkable how vegetation of M4 reduced more than 30ºC overheating on exterior face, and indoor environment remained almost 8ºC cooler than M1. However, both M2 and M3 presented similar temperature values on the slats surface. Across the chamber, vegetation and convection made temperature fall about 6ºC in M3 respect M2, and indoor environment was also cooler.

Indoor temperature values in M4 remained under values from M1 during the six days-type. These differences were quite uniform during all the day, th with a maximum range of 4ºC in August 24 . Table 4 summarizes these data, where maximum differences th th were noticed for hottest days (June 28 , August 4 th and 24 ). Table 4: Indoor temperature M1-M4 difference (∆TM1M4)

DATE nd

Jun. 2 nd Jun. 22 th July 5 th July 28 th Aug. 4 th Aug. 24

∆TM1M4 in each day-type (ºC) Average Median Max. Min. 3,66 3,48 5,40 2,45 3,39 3,10 5,40 1,90 2,62 2,45 3,90 1,85 6,21 6,10 7,90 4,85 5,37 5,20 7,30 4,15 5,35 4,65 7,60 3,70

Except for night values, temperature registered inside M4 remained cooler than outdoors temperature. Sunrise made temperatures increase, and until noon it did not exceed indoor surface temperature values of M1. The sun irradiation overheated M1, and at afternoon hours indoor surface was hotter than the outdoors (Figure 7).

Figure 7: Indoor surface temperature values (Tis) during the six days-type at M1 and M4

4.4. M2-M3 differences

th

Figure 6: Layer temperature variation for July 28 .

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Temperature values were always lowest in M3 than in M2 during the day, but not as uniformly as it was in M1 and M4. Meanwhile, night peaks in M3 remained over M2 values, composing a smallest daily temperature rank. Both indoor temperature average and median values fared quite similar for FP5 and FP6, FP1 and FP2, and finally FP3 and FP4, as seen on Table 5. Also, night ventilation made no difference for temperature values of M2 and M3. Moreover, temperature difference between the two chambers reached highs in FP6, FP2 and FP4.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 5: Indoor temperature M2-M3 difference (∆TM2M3) M2M3 Position

FP5 FP6 FP1 FP2 FP3 FP4

∆TM2M3 in each day-type (ºC) Average Median Max. Min. 2,33 1,65 5,90 0,00 2,41 1,83 5,35 0,25 3,40 3,08 6,15 1,40 3,81 3,18 7,00 1,75 1,30 0,92 3,70 0,00 1,51 1,13 4,70 0,00

FP3 and FP4 produced less vegetation influence, as suggested in Figure 8. There was not a relevant difference between FP5 and FP6 as thermal buffer both in peak and average values. The same fact happened for FP1 and FP2, but buffer values were slightly higher for FP2. Despite peak differences, FP3 and FP4 average data were almost the same.

5. DISCUSSION 5.1. Differences between the two systems Only FP1 mitigated indoor overheating in daily average more than the cladding system, during the day-type where both temperature and humidity values had lowest ranks of variation between day and night. Despite this, indoor peak temperatures were higher in M3 than in M4. For the rest of the positions, thermal buffer was more sensible through opaque wall, and indoor values in M4 were more stable during the entire day. Indoor temperature data were an average of between 1ºC and 4ºC cooler, although mitigation peaks were similar for FP5 and FP6 to those reached in M4 during the day. The differences were highest between the cladding opaque system and FP3, where thermal buffer appears to be of only 1ºC daily. 5.2. Overheating and vegetation effects Cooling effects of vegetation were remarkable in the cladding system concerning indoor temperature values. Also, these values were up to 6 hours out of phase for the South irradiance peaks (Figure 9).This lag lasted a maximum of 2 hours in M3. Moreover, overheat mitigation was stable in M4 during the day, with mild peaks, opposed to what revealed the translucent façade.

Figure 8: Indoor temperature values (Ti) for the six daystype at M2 and M3

4.5. Energy savings and comfort conditions In order to estimate energy savings, cladding panels system and translucent façade were considered separately. For the first case, maximum acceptable inner surface temperature value was 26ºC (To). Since it is not a complete enclosure of a building, this limit was chosen as suggested by Spanish Technical Building Code [12]. For the translucent façade, comfort conditions described by Olgyay for mild climates were adopted. In this summer case, acceptable temperature values are in a rank of 21,97ºC and 27,53ºC(Tol), and relative humidity should be under 50%. As Figure 7 shows, Tsi at M4 was under To during more than 94% of the time, and only overcomed this th value at July 5 . Meanwhile, at M1 Tsi remained under To for 43% of the time, almost always at night. Indoor comfort conditions were reached for 8 hours more in M3 than in M2 in FP1 and FP2, but their days-type presented lower outdoor temperature values (Figure 8). For FP5 and FP6, indoor temperature and humidity values were equal when sash window opened, at 21:00. Therefore, any energy saving considered stops at this hour. Table 6: Energy savings on cooling (hours) considered from comfort conditions in each day-type

FP1 8h

FP2 8h

FP3 2,5h

FP4 3h

FP5 6h

FP6 3h

Figure 9: Solar irradiation and indoor temperature values (Ti) for the six days-type at M1 and M4.

Unlike in the vegetated modules, thermal performance of M1 was significantly worse than M2, particularly on outer layer overheating during the noon. This fact suggested a more sensible influence of vegetation on cladding system than in translucent façade, which is a complete enclosure system. Hence, maintenance works and appropriate irrigation should be taken in care if this cladding system is placed over a blank wall as a passive cooling technique. Analyzed data also suggested a continuous mitigation of indoor overheating in M3, and FP6 being the most favourable position to maintain the comfort conditions during the afternoon for this climate. Although cladding panels revealed hygrothermally as the most effective solution, the possibility of ventilation through translucent façade must be emphasized. 5.3. Improved indoor environment More than 90% of the time, indoor temperatures were cooler in M4 than outdoors, from 1ºC to 5ºC in

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average. Also, these indoor values were close to a comfort situation, so it has been revealed as a useful input for blank façades in order to avoid summer overheating. The biggest difference between indoor M3 and outside temperature was given in FP6, with peaks of up to 9 ° C difference. The lower values of cooling were shown in FP4. Except FP6, the other positions fail to keep cooler module than the outdoor throughout the day, although this condition was maintained for one hour at positions with convection inside the chamber (FP2 and FP4) for which open all slats (FP1 and FP3). The similarities between FP1 and FP2, FP3 and FP4, and FP5 and FP6 suggest a higher influence on sash window opening and night ventilation than on slats openings than sash window opening or night ventilation, in overall performance. Again FP6 seemed to be the most favourable position, because inside the module were given lower temperatures during longest period. 5.4. Future research This study is in process, by monitoring M2 and M3 positions in different months, due to different climate conditions registered in June, July and August. This aims to confirm thermal performance suggested regardless monthly values and likely punctual day-type singularities. Currently, two new experimental buildings are being built, where the cladding green panels system will be tested and monitored. These façades will be combined with glazed areas, which will introduce the possibility of ventilation too. This will provide a real building performance data, and will lead to test and verify heat transfer models. Also there is a vegetation monitoring model in process, based on previous reports [8], since plant foliage development has shown as the most relevant factor in overheating mitigation values from 2009 to 2010. Aiming to spread the use of this façades, it is interesting to consider similar studies in other climatic regions and for other seasonal periods. Moreover, it is pertinent a study concerning the efficiency of different species that can thrive in this two enclosures, with the possibility of being native to each region.

6. ACKNOWLEDGEMENTS This study was supported by Intemper Española, S.A. over CECOS project (Technologic Development of Enclosures for Construction, Energy Savings and Energy Production in Buildings), and by Spanish Ministry of Science and Innovation inside project INVISO (Industrialized and Sustainable Housing).

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7. REFERENCES [1] Kumar, R. and Kaushik, SC. 2005, “Performance evaluation of green roof and shading for thermal protection of buildings.” Building and Environment, vol. 40, pp.1505-1511. [2] Neila, F.J., Bedoya, C., Acha, C., Olivieri, F. & Barbero, M. 2008, “Las cubiertas ecológicas de tercera generación: un nuevo material constructivo”. Informes de la construcción, vol.6, pp. 15-24. [3] Wong, N.H., Tan, A.Y.K., Chen, Y., Sekar, K., Tan, P.Y., Chan, D., Chiang, K. & Wong, N.C. 2010, "Thermal evaluation of vertical greenery systems for building walls", Building and Environment, vol. 45, no. 3, pp. 663-672. [4] Wong, N.H., Tan, A.Y.K., Tan, P.Y., Chiang, K. & Wong, N.C. 2010, “Acoustics evaluation of vertical greeney systems for building walls.” Building and Environment, vol. 45, no. 2, pp. 411-420. [5] Onmura, S., Matsumoto, M. & Hokoi, S. 2001, “Study on evaporative cooling effect of roof lawn gardens.” Energy and Buildings, vol.33, pp. 653666. [6] Hoyano, A. 1988. “Climatological uses of plants for solar control and the effects on the thermal environment of a building”, Tokyo Institute of Technology, Japan. [7] Eumorfopoulou, E.A. & Kontoleon, K.J. 2009, "Experimental approach to the contribution of plant-covered walls to the thermal behaviour of building envelopes", Building and Environment, vol. 44, no. 5, pp. 1024-1038. [8] Cheng, C.Y., Cheung, K.K.S. & Chu, L.M. 2010, "Thermal performance of a vegetated cladding system on facade walls", Building and Environment, vol. 45, no. 8, pp. 1779-1787. [9] Stec, W.J., van Paassen, A.H.C. & Maziarz, A. 2005, "Modelling the double skin facade with plants", Energy and Buildings, vol. 37, no. 5, pp. 419-427. [10] International Standards Office, 2005. ISO 15927-4 Hourly data for assessing the annual energy use for heating and cooling. Geneva: ISO. [11] Lee, K., Yoo, H. & Levermore, G.J. 2010, "Generation of typical weather data using the ISO Test Reference Year (TRY) method for major cities of South Korea", Building and Environment, vol. 45, no. 4, pp. 956-963. [12] Architecture and Housing Policy Directorate General of the Ministry for Housing of Spain, 2008, Technical Building Code (TBC). Madrid: Higher Council for Scientific Research (CSIC).

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Housing beyond the technical, a social realisation A comparative examination of energy efficient housing PHILLIPA MARSH1 1

School of Architecture & Built Environment, University of Nottingham, Nottingham, UK

Housing is often identified as a core contributor to the UK energy concerns (Edwards & Hyett:2002; DECC:2009), to which housing design has increasingly focused on technical efficiency to limit this issue. This technical focus appears prevalently linked to delivering efficiency, but limitedly highlights the social dimension that these technologies may have an impact on. In losing sight of the social, many technical oriented built environments have been shown to be significantly less efficient during their occupancy than predicted (Rochracher & Ornetzer:2002; Chappells & Shove:2001). The pessimistic presentation of a ‘doom-and-gloom’ scenario to technological inclusion has become evident, however this paper looks takes a more rounded view, in examining technology beyond functional efficiency; not entering into the beneficial/detrimental debate of technocentric design. Through literary reviews and comparative study of two occupied exemplars, this research will consider the inclusion of technologies from a functional and social perspective that is the basis of Feenberg’s (1999) instrumentalisation model. In doing so, this paper highlights the concept of sustainable housing beyond a means of technical efficiency and considers wider social values of the domestic environment. For designers, moving beyond the technological view may offer opportunities to be perceived less as technical administrators (Williams:2008) and more aligned to the creative social practices inherent to pre-existing Design practice. Keywords: Feenberg, sustainable design, social, technologies, housing

1. ENERGY EFFICIENT HOUSING & THE ESSENCE OF TECHNOLOGY “The house is not a device but an extremely rich and meaningful life environment” (Feenburg:1999, xi). Within the UK, housing has become a principle factor in addressing the nation’s energy concerns, with almost a third of UK carbon emissions produced from burning of fossil fuels in domestic environments (Edwards & Hyett: 2002; DECC:2009). In light of this, continual attention has been placed on technological efficiency; promoting technological inclusions as means to achieve efficiency (Smith:2003). This dominating technocratic emphasis is argued to misinterpret sustainable philosophies, losing sight of the socio-cultural elements (Guy & Moore:2005). Equally, some technically-oriented built environments have been shown to be significantly less efficient than predicted due to the limited account of the social complexity of technical change (Rochracher & Ornetzer:2002; Guy & Shove:2000). Mainstream domestic environments present a substantial challenge to sustainable architecture in its relationship between society and nature. Dwellings can be seen to represent social practices that produce and transform different natures and different values (Macnaghton & Urry:1998). Equally housing can provide a vehicle to aid in developing elements of community; creating sustainable communities in a resource efficient manner (Guy & Moore:2005) and reflecting relationships between the individual, family and community (Mallett:2004). Housing can therefore be seen more broadly than simply technical efficiency, bringing the physical, social and cultural factors into one agenda (Edwards

& Hyett: 2002). If the house environment is framed simply by valued social meanings, it may be that domestication or ‘making it ours’ have little do with functional efficiency (Feenberg:1999). This paper will examine sustainable architecture that is focused on common energy efficient technologies and the consideration of the occupants of sustainable housing projects specifically. Energy efficiency provides a specific insight of the wider sustainable field, and housing offers foci to the broader built environment context. Predominantly the preoccupation of this work looks to develop a deeper understanding of technology within a socialised context and in the specific housing environment; questioning technology and its wider value. To determine this essence of technology, this work relates to Feenberg’s (1999) instrumentalisation theory as an analytical approach. Here technology’s essence is based on crosscutting the boundaries between the social and the technical, not the distinction of these ingredients, refer to figure 1. Differentiation Primary Instrumentalisation

Secondary Instrumentalisation

Decontextualisation Autonomy Reduction Positioning

Systematisation Mediation Vocation Initiative

Concretisation Figure 1: Instrumentalisation Theory (from Feenberg:1999).

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This model works on two levels. The first level seeks to find affordances that can be mobilised in devices and systems, and the second level introduces designs that can be integrated with other already existing devices and systems that have various social constraints; such as ethical and aesthetic principles (Feenberg:2005). The value of this approach is that it has absorbed wider grounded theories, and evolves these within a pragmatic realised context. The primary level of the model is similarly reflective of Heidegger (1977) and Habermas’ (1970) differentiation theories, that were themselves framed on Weber’s similar propositions relative to premodern and modern societies. In these notions, differentiation was between the technical and social, seen as an unavoidable consequence. However the concept of technical action, whether relative to the object (Heidegger) or the subject (Habermas), appears to limit the essence of technology to these segregated categories. Technical and social differentiation can be overcome in the secondary level as contextualisation (Veak:2006; Feenberg & Feng:2008). Thus by taking a two-level perspective, the wider relationships to broader contexts can be presented with simplified technological perspective; understandings how simplified objects integrate into social environments. At the core to Feenberg’s theory is that the social dimensions of technological systems belong to the essence of technology (Feenberg: 1999). As this work will show, the emphasis of functionalised technology clearly dominates much of sustainable housing thinking however this view provides a restricted and basic perspective on technology; as neutralised tools. Sustainable housing literature appears to skim the surface of already establish philosophical perspectives where technology is often discussed as part of value-laden networks (Latour:1993) or where socialised values directly shape technological systems (Bijker et al:1989; Mackenzie & Wajcmann:1985). The instrumentalisation theory offers an opportunity to progress from these pre-existing views of technology, and a mediation between the celebration of technocratic triumphant versus the gloomy Heideggerian prediction of techno-cultural disaster (Feenberg: 1999). Using pilot research findings, later discussions will demonstrate the presence of socialised values in the energy efficient home environment and their potential to influence the acceptance of efficient technology. Discussions will loosely apply Feenberg’s model, using views of autonomy and mediation, to energy efficient housing. It will consider the emphasised functionalisation and the missing social realisation during occupation. There are some clear distinctions of what is and is not attempted in this work. Firstly, this paper aims to advance the perspective on social architecture rather than attempting to directly impact on sustainable theory overall. Using interdisciplinary perspectives, discussions will show the wider sustainable considerations and the missing values of social contexts within current sustainable architecture. Secondly, this research will look to develop a more detailed social perspective; it does

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not intend to enter into the debate of defining efficiency or sustainability directly. Finally, by highlighting the overly dominant technological focus, this research is not looking to restrict the value of the technical dimension, more that the social considerations should complement and not compete with technology (Moore: 2001). Overall these discussions propose a move away from the narrow focus on technological and economic perspectives as currently shown in sustainable architectural disciplines and more the need to combine this alongside the sociological standpoint to fully determine the sustainable achievement.

2. EMPHASISING FUNCTIONALISATION IN ENERGY EFFICIENT HOUSING “Technology is the single most important generator of design conscious. It is not what buildings are but what they do and how they do it” (Edwards & Hyett:2002, p.158) A wide spectrum of literatures has been reviewed, contextualising sustainable housing as the key dynamic of this investigation. Literatures were considered from grounded notions related to sustainability, technological and social change, housing, dwelling and the built environment. Sustainable architectural literature within the built environment was seen to present energy efficiency housing through the inclusion of efficient technologies (Edwards & Hyett:2002) and a ‘how it works’ or ‘can do’ perspective (Roy & Herring:2007). The technical functionalised agenda appears dominantly but does not look beyond the pragmatic achievements. However there appears to be a growing dissatisfaction with this approach which presents a potential to reconsider this dominance to include the more detailed social considerations within energy efficient housing practices. Within much of energy efficient housing literature, the notion of improving buildings’ functions and the technical elements were at the core of sustainable efficiency. Whilst this is important, it often curbs recognition of the housing environment and the presence of its social values. Sustainable literature showed an underlining persistence to this standpoint; the neutralised view of technology is the key driver to achieving energy efficiency. Innovations can often be seen as hard ‘facts’ that offer a measurable success to solved necessary problems (Williamson et al:2003). The descriptor for an existing energy efficient housing project highlights this well: “The design uses a high performance factory built panellised building fabric together with micro generation, mechanical ventilation and low-impact heating technologies, that help achieve significant reduction” (Zero-carbon Hub:2009) This reflects notions of the primary functionalisation outlined by Feenberg’s (1999) theory, representing sustainable housing as neutralised technological tools. The inclusion of energy efficient tools within sustainable housing enables a means of determining the situation and discovering a range of technically efficient answers

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

(Williamson et al: 2003). Technically efficient structural components, construction details or the inclusion of appropriate appliances/devices are commonly presented in the literature as measures to achieve efficiency. These are then proven successful through measureable factors; such as statistics, ratings, external reports, or abiding with predetermined conditions in regulatory codes, thus limiting the potential socialised values. Technology as a tool to enable efficiency can be shown as socially value-neutral; social considerations were limitedly valued. In some approaches, such as the Balehaus project in Bath, this notion was reflected in their evaluative approach; using a simulated approach to human occupation using timed light bulbs. This was seen as more preferable to determining efficiency (Beadle et al:2009), but emphasises the view of occupants as ‘barriers’ to the energy efficiency (Guy & Shove: 2000). Many projects considered social factors but continued this as a validation of the success technology; occupants’ ability to use the measures. The Oxford Eco-house highlighted an example of this. The house is described as liveable and occupied but focuses on this in terms of a working home which can test and prove the solar technology (Roaf:2007). Some projects did present an alternative view in examining occupants’ responses to energy efficiency. The EoN house, part of the Creative Homes project at the University of Nottingham, endeavours to consider energy efficiency alongside occupational habits (EoN:2008). However these approaches can accentuate the functional view of technology primarily; understanding social behaviours to inform efficient use of the technology not understanding behaviours in sustainable house environments. Occupational considerations and evaluations simply offer another means of measuring technical efficiency, not a socially realised notion in the home environment; contextulising technology into a value-laden sociocultural context (Feenberg & Feng:2008). There appears to be a growing scepticism of this techno-centric functionalised approach within architectural literature. Some identify the dominance of technology as a means to hide behind the measurability of science (Tyszczuk:2009). Others show a rushed reliance is reflective in the potential for technological failure (Williams et al:2008). Sustainable architecture can appear to be providing ‘technological fixes’ with limited social considerations (Till:2009). Whilst ‘fixes’ may provide some benefits, they may not provide all the answers (Guy & Shove:2000) and presents a one-sided primarily functionalised approach to efficiency. Broadly viewed, such perspectives can enhance an illusory visions of technological salvation and the dangers of isolating sustainable architecture as solving technical problems (Wines:2000).

3. REALISING THE SOCIAL THROUGH ENERGY EFFICIENT CASE STUDIES “The house is not a device but an extremely rich and meaningful life environment. Yet it has gradually

become an elaborate concatenation of devices” (Feenburg:1999, xi). Having outlined the functional dominance of technology, case study research was conducted to determine a wider view of the technological context of energy efficient housing. Two projects were chosen as pilot case studies in Nottinghamshire. Initially, the project intentions for these may appear on the surface different; one sought to present the possibilities for a sustainable community approach to self-supported living whereas the other aimed to demonstrate how new materials and technologies can be used to create an energy efficient and affordable home. Whilst these differences are distinct, the overarching aim of both projects offered similarity; in minimising the environmental impact and maximising energy efficiency through the use of materials. Thus these projects offered a useful case basis for further analysis. To determine these more socialised realisations, unstructured interviews were conducted with occupants of both housing projects. Interviews were conducted to identify qualitative results related to their experiences of energy efficient technologies in the home environments and their perceptions of efficiency. It is important to note that as pilot studies, these results are not fully conclusive but do provide a ‘social’ insight into users’ actual experiences of living in existing energy efficient housing; in terms of the acceptance and adoption of energy efficient practices and the potential for further investigation. Overall results showed that measures offered key benefits in influencing their living patterns, in terms of how they interrelated to the measures within the design. In some instances notions of hidden measures were shown preferably; in terms of insulation offering an unseen way of achieving energy efficiency. However, in other cases occupants highlighted the need to draw attention to the measures; such as incorporating recycled materials that offered embodied energy but also made a statement about the essences of the project or the homeowner. Pragmatically, findings also suggested the apparent need to consider maintenance and flexibility of the design. Many discussions centred on the inconvenience of maintaining new measures and the flexibility for adaptation for living, specifically over ‘normal’ or conventional house types. As will be shown, this can have a direct impact of use and potential adoption of these energy efficient measures, or indeed the characterisation of the house environment. 3.1. Mediating technology in use – embedding in context Results from both interviews highlighted aspects where occupants coped with technological difficulties, relative to unfamiliar technologies and unfamiliar user actions. Whilst evidence of similar results has been found in other research projects, the impact of how users felt; their experiences and the subsequent perceptions of the technologies, are less covered. The process of persevering and

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whether users were happy with the results of their actions offers a link to the potential for accepting the technology into their social environment: “difficulties can mean you don’t want to use them or you work them out” “some things take time to get right, but then you work them out & see that it does work” Perseverance was discussed by some occupants more, in terms of their involvement and the resulting rewards they receive; whether their actions delivered positive or negative results and if these were considered worthwhile. The ventilation technology was one example of this, where the occupant described their initial perception of the technology as, “a simple premise that was hard to understand at first, what to open/close or when to use it”. Once understood, the occupant described the technology as: “it works well because you see and feel physically what it does...it’s satisfying to work it out”. This occupant shows that in seeing the results of their actions, they reflected positively on the technology. There is an additional value, in working out the mode of operation successfully. However not all evolutionary perceptions of the technology resulted in a positive reflection. Some technologies were viewed negatively after users persevered with unfamiliar technology and their actions. The Biomass technology was one example that the occupant described as a: problematic technology...it took 7 months to fully understand the system...sometimes, it was impossible to light it. To make sure we’d get warm showers when there was not enough solar radiation, we’d used the immersion control and a few times we use electrical heaters, neither are energy efficient”. The user appears as a central actor in these evolutionary technological processes where users’ understanding of the technologies’ functions were shown to impact on their awareness of wider conditions. Users appeared more aware of their affect on efficiency. As they became familiar with the technology, they show awareness not simply on how the technology works but in some cases why it works to achieve efficiency. These results are relative to Norman’s (2004) theory on technological attachment, where users’ behavioural involvement in operating the technology is a key level to developing an attachment and acceptance of that technology being embedded in context. These values form user’s attachment to a technology and can be short/long term values dependant on the attained stage (Norman:2004). Forming attachment is often shown in line to the concept of self (Ball and Tasaki:1992; Kleine et al:1995) thus repeating the social dimension. Ball and Tasaki (1992) show that attachment, and subsequent detachment, for an object develops over five stages: pre-acquisition, early ownership, mature ownership, pre-disposal, and post-disposal. Once something is accepted, it often belongs to one of the three intermediate stages of attachment: early and mature ownership and predisposal. This, in part, is resonant to notions of lifecycle, and often referenced in response to retaining attachment in alternative views of sustainability. Till (2009) also relates the

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transient and durable objects to the renovations of Georgian terrace housing which creates value and (ideally) infinite life spans. In both Ball and Tasaki (1992) and Till (2009) recommendations to prolonging lifespan through durable or attached values in essence relates to the sustainable premise, but one which again appears restrictive in much of sustainable housing discussions. The notions of technological acceptance parallel to wider literature that considers technological efficiency with housing. Rybczynski (1987) illustrated that efficiency is more in tune with user comforts, demonstrating that inefficient used or misused of technologies often occurred because the technology addressed the home physical, behavioural and psychological comforts of the occupants. Harris (2009) echoes this idea, showing the impact of comfort on the adoption of cast iron stove technology in a historically US housing context. His work stresses that to be accepted into daily life, the technology needed to offer values of comfort in terms of convenient efficiency. These findings demonstrate that a technology can be positively and negative received into a social context. It is not simply the answer to say that a technology functions in one way and then to evaluate how the user interpret this. More so, these findings shows that understanding the contextualised embedding of technologies within an environment can relate to both users’ actions, involvement and the processes they experience as well as the technicalised functions of the technology. The varying results from all of these can therefore lend to the mediation of technology. 3.2. Mediating with domestic values & meanings- embedded into a homely context Interestingly within much of the established sustainable housing literature, notions of domestic values and meanings are limited reference, if not ignored. This research has found that in these sustainable case studies, housing values are still present in occupants’ considerations. In both cases, the house appeared to offer a distinct value to the occupants primarily as a means of energy efficiency use rather than as domesticated home: “The character of the house is different. Because of the technology & what you have to do, it feels like more of a technical energy device than home.” Whilst these results reflect technised values, in part due to the projects’ premise as conceptual exemplars, the findings also suggest notions of a different value to these house environments. The traditional notion of home appears in these environments by the occupants; in adapting and developing the environment to suit their requirements and tastes. At times occupants discussed how the original design offered the potential for homeliness: “Some of the spaces feel quite homely, in that you can have your own space and hide”) However others discussed the difficulties that these designs had to fully form a value of home: “if I wanted to make it more mine, as my home, I’d have to change this, that affects the way it works”

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

These views highlight the restrictions of the designs for users to adapt to their preference and the impact that other features might have on efficiency. Whilst these are physical adaptations, the premise appeared as a desire to personalise. Occupants suggested a need to make a home theirs to which reflected the need to physical change the design. This corresponded with perceived missing features, focal points and valued features that provide a feeling homely comfort. In both cases the fireplace was outlined as a key homely feature, a concept Holl (2006) echoes where the fireplace offers a means of experiencing the home through values of comfort and intimacy. The experience within the home relates to developing values and associated meanings that merge the space to the individual involved. These ideas ultimately return to Feenberg’s (1999) paradigm of the house environment framed by valued social meanings and technological inclusion. Housing is therefore not simply about the physical function as a shelter but as psychological security, drawing connotations of societal status, a communal or family base and a haven for privacy to maintain well-being (Daly & Daly:1996). Mallett (2004) questions the notion of home, relating this to the house, family, haven, self, gender and journeymaking. Danby (1993) addresses similar thinking in context to architectural design, suggesting that housing can reflect the relationship between individual, family and community. Thus a home has much broader connotations than the physical and functionalised house referenced within sustainable works, aligned to the meanings of house, household, dwelling, refuge and affection. From these results, this work suggests that it is not simply enough for post-occupancy evaluation to consider technologies and users efficient use or misuse. More so this research has shown that there is a different level of understanding to technology when implemented into the social and natural environment; understanding the mediation or embedding into the social context. This mediation, outlined by Feenberg’s (1999) realisation stage, has been shown to be lacking in the current perspectives of energy efficient technologies within housing. However as these initial results show, in taking this more developed view of technology, a fuller concretised understanding of technology within the embedded social environment can be determined.

4. A ‘SOCIAL’ CONCLUSION BEYOND THE TECHNICAL

LOOKING

“Environments do shape technologies but are in turn shaped by them...technologies do shape places but in turn are shaped by them” (Moore:2001, p. 54.) From this critical review, an apparent limitation to the socio-technical perspectives has been presented. Not only is there a need to consider the social elements in context to efficiency within sustainable housing but also to consider the interrelating factors between technology and social contexts within the housing environment. In understanding the technological emphasis within sustainable housing

literature, there is a clear socio-technical disparity of extremes. To one extent, sustainable architectural literature appears to separate the technology from the social, considering technical functions to be a means of measurable efficiency. To the other, the social dimension was included but from a limited functionalised physical view; evaluating occupants’ use of the technology. The core focus of this paper centres on domestic housing, highlighting the importance of this area beyond being technically efficient. It has identified a more widespread consideration to social elements; comfort, acceptance and adoption of technology as well as showing a consideration to ‘home’ in understanding the social relationship of domestic project. Whilst this focus may appear specific, there is strong correlation to the wider understanding of technologies and the built environment alongside society, thus expanding the sustainability debate. The question therefore remains, why is this research relevant? These critical discussions provide opportunities for sustainable architecture to reconsider the domestic environment, and to reinterpretation current architectural views on energy efficient housing, as a means of reconnecting to the domestic environment. This work is not simply showing that the social dimension is important and needs wider consideration. Discussions support the need to reinterpret energy efficient housing environments beyond the view of technical efficiency and expand considerations to social notions of home, dwelling, technology, comfort and efficiency. Through a wider understanding, sustainable practice has the opportunity to reconnect with the domestic environment alongside the application of technical efficiency and developing a broader view of sustainable housing; in the perception of efficiency alongside the values of the domestic environment. Having determined the current standpoint of sustainable housing literature to be highly limited, it would be quite simple to present this piece as a pessimistic dismissal of technological notions and alternates this by calling for the inclusion of social dimension. However this work draws similar parallels to Moore’s (2001) thinking to the context of place, technology and sustainable practice. The inherent interrelationship between social, technological, and place needs to be considered to fully determine a clear understanding. By emphasising one over others appears to have clouded a picture; providing a view of a technical environment, whilst not understanding the other social constructs that are influential within this network.

5. ACKNOWLEDGEMENTS This paper acknowledges the help and guidance from Graham Farmer of the University of Newcastle, and Michael Stacey of the University of Nottingham. It also notes the Architecture and Urbanism research division of the University of Nottingham for it welcomed support to enable this research to proceed.

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6. REFERENCES [1] Ball, A. D., & Tasaki, L. H., (1992). The role and measurement of attachment in consumer behaviour, Journal of Consumer Psychology, 1(2), 155-172. [2] Beadle, K., Gross, C., & Walker, P., (2009). Balehaus: The design, testing, construction and monitoring strategy for a prefabricated straw bale house, Non-Conventional Materials & Technologies Conference, Bath. [3] Bijker, W., Hugher, T., & Pinch, T., (1989) The Social Construction of Technological Systems: New Directions in the Sociology and History of Technology, MIT Press. [4] Chappells, S., & Shove, E., (2001). Debating the future of comfort: environmental sustainability, energy consumption and the indoor environment, Building Research & Information, vol. 33, issue 1, pp. 32-40. [5] Daly, G. & Daly G., (1996). Homeless: policies, strategies, and lives on the street, Routledge. [6] Danby, M., (1993). Privacy as a culturally related factor in built form, in Framer & Louv (1993) Companion of contemporary architectural thought, Routledge. [7] Department of Energy and Climate Change, (2009). Digest of United Kingdom energy statistics, DECC. [8] Edwards, B. & Hyett, P., (2002). Rough guide to sustainability, London: RIBA. [9] EoN (2008) Project objectives, EoN. [10] Feenberg, A., (1999). Questioning technology, London: Routledge. [11] Feenberg, A., (2005). Critical Theory of Technology, Tailoring Biotechnologies Vol. 1, Issue 1, pp: 47-64 [12] Feenberg, A., & Feng,P., (2008). Thinking About Design: Critical Theory of Technology and the Design Process, in P. E. Vermaas et al. (eds.), Philosophy and Design. Springer. [13] Guy, S. & Shove, E., (2000). A Sociology of Energy, buildings & the environment, Routledge [14] Guy, S. & Farmer, G., (2001). Reinterpreting Sustainable Architecture: The Place of Technology, Journal of Architectural Education, pp. 140–148. [15] Guy, S., & Moore, S., (2005). Sustainable architectures: cultures and natures in Europe and North America, Taylor & Francis. [16] Harris, H., (2010). Conquering winter: US consumers and the cast-iron stove, from Shove, Chappells, & Lutzenhiser, L. (eds), Comfort in a Low Carbon Society, Routledge. [17] Habermas, J., (1970). Technology and Science as ‘Ideology’, in Towards a Rational Society, trans. J. Shapiro, Beacon Press [18] Heidegger, M., (1977). The Question concerning Technology, trans. W. Lovitt, Harper Row

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[19] Kleine, S. S., Kleine, R. E., & Allen, C. T., (1995). How is a possession “me” or “not me”? Characterizing types and an antecedent of material possession attachment, Journal of Consumer Research, 22(3), 327-343. [20] Latour, B., (1993). We have never been Modern, New York: Harvester Wheatsheaf [21] MacKenzie, D., & Wajcman, J., (1999). The Social Shaping of Technology, Open University Press. [22] Macnagton, P., & Urry, J., (1998). Contested Natures, Sage Publishers [23] Mallett, S., (2004). Understanding home: a critical review of the literature, The Sociological Review 52, (1): 62–89, February 2004. [24] Moore, S., (2001). Technology & place: sustainable architecture & Blueprint Farm, University of Texas Press. [25] Norman, D., (2004). Emotional Design, New York: Basic Books. [26] Roaf, S., (2007). Ecohouse, Architectural Press. [27] Rochracher, H., & Ornetzer, O., (2002). Green Buildings in context: improving social learning processes between users and producers, Built Environment Journal, 28, (1): 73-84. [28] Roy, R. & Herring, H. (2007). Technological innovation, energy efficient design and the rebound affect, Technovation Journal, 27, (4): 194-203, April. [29] Rybczynski, W., (1987). Home: A Short History of an Idea, Penguin Books Ltd. [30] Smith, A. (2003). Transforming technological regimes for sustainable development: a role for alternative technology niches? Science and Public Policy, volume 30, number 2, April 2003, pages 127–135. [31] Till, J., (2009). Architecture Depends, MIT Press. [32] Tyszczuk, R., (2009). Architecture and Interdependence, Ethics & the built environment Conference, University of Nottingham [33] Veak, T., (2006). Democratizing technology: Andrew Feenberg’s critical theory of technology, Suny Press [34] Wines, J., (2000). Green Architecture: The Art of Architecture in the Age of Ecology, Taschen. [35] Williams, A., (2008) Enemies of Progress: Danger of Sustainability, Imprint Academic [36] Williamson, T., Radford, A., & Bennetts, H., (2003). Understanding Sustainable Architecture, Taylor & Francis. [37] Zero Carbon Hub (2009). LZ carbon profile: ecoTSenntECH Organics Smart House, BRE

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Turn the gas off Zero-energy achievement based on free floating internal conditions between health-related limits Geoffrey van Moeseke1 1

Architecture et Climat, Université catholique de Louvain, Louvain-la-Neuve, Belgium

ABSTRACT: The current trend in low energy building design is to reduce heating needs at ambitious levels – e.g. the Passive House concept - and to compensate residual consumptions with renewable. This leads to so called net-zero-energy buildings. This paper explores another possible definition of zero energy: a building that, without mechanical heat supply, maintains winter internal conditions between health related limits. Thanks to dynamic simulations, it is shown that an apartment designed according to passive architecture best practices is matching this definition. The paper concludes on a proposition of shared responsibility between the designers and the inhabitant: the passive achievement of healthy indoor conditions is the designer’s responsibility, while the achievement of more comfortable indoor conditions falls to the inhabitant’s share. Keywords: Zero energy, Passive House, free float, health, comfort

1. INTRODUCTION 1.1. Energy design tendencies The net-zero-energy buildings (NZEB) concept is now strongly promoted : the European Parliament recently approved a recast of the Energy Performance of Buildings Directive proposing that all new buildings in the EU be at least ‘net-zero energy’ by 2019 [1]. Hernandez and Kenny give an interesting overview of the NZEB concept [2]. According to them, “the most common approach to ZEB is to use the electricity grid both as a source and a sink of electricity (…). The term ‘net’ is used in grid connected buildings to define the energy balance between energy used and energy sold, the term ‘netzero energy’ being applied when the balance is zero”. They show that the actual definition of NZEB is not satisfactory, especially because it is not base on a life cycle approach. Another criticism of NZEB concepts is that they are not very useful at the design stage. Only two attitudes are possible at this stage. The first one is to determine the energy supply capacity of the site and to design the building in order to be lower or equal to this value. If the supply capacity is high, there is no guarantee that the building will be energy efficient. Such an attitude does not follow the Trias Energica [3]. The second attitude is to design the building as energy efficient as possible, and then to care about renewable energy supply sources in order to overwhelm the residual energy consumption. This attitude corresponds more to concepts such as “Passive House” [4] supplemented with renewable than to the NZEB concept. 1.2. Objective From this introduction we formulate the following question: are they other ways to design net-zero energy buildings than through the idea of grid connected buildings? Obviously, there is one

solution, which is designing a building that actually does not use energy to maintain healthy indoor climate conditions. Next to a carbon footprint limited to embodied energy, such a building would ideally tackle fuel poverty. It would answer to environmental, social and economical aspects of sustainable development. The aim of this paper is to check whether a dwelling designed according to Passive House principles may fulfill this definition. Since internal gains are a major factor in a passive house energy balance, the evaluation has to be conducted for occupied dwellings. But it cannot be asked to inhabitants to live a winter season without heating. So the evaluation is done through dynamic simulations.

2. METHODOLOGY In order to complete this exercise, we describe the studied dwelling (section 2.1) and define simulation parameters (section 2.2). We also discuss indoor climate conditions. At first, we consider commonly accepted comfort zones (section 2.3). Then, following the idea that before being comfortable, a dwelling should be healthy, healthy conditions are proposed based on existing literacy (section 2.4). 2.1. Example dwelling The 119m² apartment investigated is shown in figure 1. An 11 zones model is created in trnsys17. Technical data’s are summarized in table 1. Two performance levels are investigated. The first one allows the apartment to fulfill Belgian criterions of the “Passive house” standard (heating demand <15kWh/m²an and n50 infiltration rate <0.6). The second one proposes further improvements. Internal gains are integrated in order to represent a 4 person family with typical working schedules. Metabolic gains represent 1.8MWh/y, equivalent to a

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Figure 3: Temperature profile for the reference year and the cold wave Table 2: Meteorological monthly values Figure 1: Studied apartment plan: 2 north rooms, 1 south room, south living room and internal technical spaces Table 1: Technical apartment

characteristics Case 1

Construction type External wall Glazing

of

the

Passive

Case 2

Massive concrete building with outside insulation 0.183 W/m²K 0.10W/m²K 0.7 W/m²K+ 0.52 W/m²K spacer g=0.59 g=0.5

Frame

0.87W/m²K

0.87W/m²K

Hygienic ventilation

Mechanical inlet and exhaust

Mechanical inlet and exhaust

Flow rate

144kg/h 0.43 ach

144kg/h 0.43 ach

Heat exchanger

Flat plate Constant 76% efficiency

Hygroscopic Constant 80% efficiency

4.3 m³/hm²

2m³/hm²

External wall air tightness Q50

constant gain of 1.7W/m² (gross floor area). Daily occupation profiles are shown in figure 2. Electrical consumptions relative to lighting and other uses represent 1.8MWh/y. This value is lower than the 2.5MWh/y value representative of a Walls family of 4 people without electrical cooking facilities [5]. The cumulated value of internal gains is 3.55MWh/y, equivalent to a constant gain of 3.4W/m² (relative to gross floor area). This is higher than the typical 2.1 W/m² (net floor area) proposed in the Passive House certification assessment tool [6] but nevertheless seems representative of actual conditions in an apartment.

Figure 2: Daily occupation profiles

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Coldest month of the typical year

Cold wave

Mean temperature °C

2.5

-2.4

Min. Temperature °C

11.3

11.1

Max. Temperature °C Global horizontal radiation kJ/m²/month

-7.9

-14.9

72306

76223

Humidity production is considered. A 65gr/h/person production is assumed. Cumulated with vapor production in the bathrooms and the kitchen, an average humidity production of 6.3l/day (0.053 l/day/m²) is obtained. Trnsys17 capacitance humidity model is used with a humidity capacitance ratio of 4 in every zone. 2.2. Simulation parameters Simulations are conducted for both an extreme winter month (“cold wave”) and a typical Belgian winter (Meteonorm file for Uccle). Figure 3 shows external temperature profiles. Table 1 summarizes meteorological values for the cold wave and the coldest month of the typical year. The simulation is conducted with a 0.5h time step and a 6 month initialization period. 2.3. Definition of comfort zones Criticisms are expressed against too simple definitions of thermal comfort. Especially, the variability of comfort feeling with the subject behavior and their adaptation to the climatic conditions has been discussed [7]. So called adaptative approaches based on field surveys have been developed to define thermal comfort guidelines including both physical parameters and behavioral and psychological parameters [8, 9, 10, 11]. Nevertheless, traditional comfort zone definitions explicitly consider ambient humidity, while adaptative methods use functions of the external and indoor operative temperature only. Since the humidity ratio is a key parameter regarding health, as exposed in section 2.4, we choose in this study to consider traditional comfort indexes. Two comfort zones are drawn in the psychometric chart (Figure 4). The first one is the ASHRAE Standard 55-2004 acceptable range of temperature based on a PMV evaluation [12]. The

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 4: Health and comfort limits.

second one comes from ASHRAE handbook 2005 [13]. This last one includes a minimal humidity limit. Both comfort zones are originally defined regarding operative temperature. In order to express all our results in ambient air temperature we make the hypothesis that operative and ambient temperatures are equals. This implies that Tmrt=Tamb. Thanks to high insulation levels, highly compact design and mostly convective internal gains, we consider this hypothesis as reasonable in Passive Houses. We invite the reader to keep in mind that if Tmrt
into account transient situations, although resistance and sensibility to climatic variations should be considered. So the limits of the proposed “healthy zone” are to be seen as indicative only. The proposed temperature and humidity limits are expressed as mean ambient conditions. It must be kept in mind that mean internal conditions are not representative of local conditions, such as those occurring on cold bridges. Nevertheless, we will assume such equivalence. This assumption is supported by the high insulation levels and the exhaustive resolution of cold bridges asked for by the Passive House concept. Both elements help bring about small differences between surface and ambient conditions. The proposed limits are the following: 1/Maximal humidity: excessive dampness appears to be the most determinant parameter for fungal growth and house dust mites. Laboratory measurements have demonstrated that mould grows when wall surface RH is above 80% for a period of several weeks, although some moulds will grow at relative humidity as low as 70% [18]. It is usually accepted that a relative humidity of 70% is sufficient to sustain mould growth [16, 19]. About dust mites, maintaining a relative humidity lower than 50% thorough the year is recommended in homes [20]. This limit should be respected for mean daily RH, with maximal periods for 2 to 8 hours daily above 50% [21]. Also, it has been shown that almost no house dust mites are able to survive below 45% relative humidity at 20–22 °C but at higher humidity the number of mites increases rapidly [22]. The World Health Organization set a figure for absolute humidity of 7g/kg as the limiting factor for the growth of colonies of dust mites [23]. Below this level numbers of mites begin to fall, due to direct desiccation of the mites themselves plus the dehydratation of the skin scales on which they feed. This last expression of maximal humidity is in good agreement with the 50%RH limit for temperatures between 18 and 21°C, but stricter for higher temperatures. Considering that dust mites are hazardous only for allergic people while mould is hazardous to everyone, both maximal humidity limitations do not have to be regarded as equivalent. Only the mould related humidity limit will be considered further. 2/Minimal humidity: Too dry conditions cause the development of irritation symptoms in eyes and upper airways. Studies indicate that RH about 40% is better for the eyes and upper airways than levels below 30% [24]. It is also shown that the occurrence of upper respiratory tract infections increases when indoor relative humidity is below 30% [16]. 3/Minimal temperature: Below 18°C the risk of adverse effects – respiratory infections, bronchitis, heart attacks, stroke – rises. The risk increases the more temperature falls. Below 10°C the risk of hypothermia becomes appreciable, especially for the elderly [15]. Other studies have shown that 15°C appears to be the threshold temperature for pressor effects in elderly people and therefore this would be a minimum level at which elderly people should live in their homes [25].

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3. RESULTS Results for cases 1 and 2 for the coldest month of the typical year are shown in figures 5 and 6. Figures 7 and 8 show results for the cold wave. In all those figures, each dot represents a daily mean value in one thermal zone. Figures only show thermal zones with long term standing, e.g. the living room and sleeping rooms. Figure 5 indicates that the gap between internal conditions and health related limits is large during the coldest parts of a typical year in Brussels. It is of course worse for a more extreme period (Figure 7). Thanks to technical improvements (case 2) healthy conditions are achieved for typical periods (Figure 6), but not for extreme periods (figure 8). In order to illustrate daily variations, figure 9 shows hourly values for the coldest week of the year for the living room in case 1 and 2. Daily variations appear to be horizontal ones, indicating temperature shifts of 2 to 3.5°C and absolute humidity stabilit y. This stability indicates an adequate hygienic ventilation rate.

crucial. We assumed neither winter holidays nor even an evening totally unoccupied. Such reductions in internal gains would result in lower temperatures. It is well know that Passive House standards achievement is rather sensitive to internal gain variations. Those gains typically account for 1/3 of the heat demand [26]. In the case of apartments, thanks to very low conductive losses, this proportion is higher. For the coldest month of the typical year, it reaches 47% in case 1, while solar gains only account for 15%. Figure 10 shows, for the coldest week of the typical year, values of internal and solar gains and total heat demand and supply in order to maintain a 21°C ambient temperature, for case 1. 4.2. Use Our results demonstrate that it is possible to achieve healthy conditions thanks to passive heating measures only, for an occupied apartment and

4. DISCUSSION This section discuss interpretation and use of the results exposed in section 3. 4.1. Interpretation Both case 1 and case 2 use existing technologies and correspond to best practices matching Passive House recommendations. The hypothesis of a continuous occupation is

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Figure 7: Internal conditions in the living and sleeping rooms of the “case 1” apartment for a coldwave.

Figure 5: Internal conditions in the living and sleeping rooms of the “case 1” apartment for the coldest month of a typical year.

Figure 8: Internal conditions in the living and sleeping rooms of the “case 2” apartment for a coldwave.

Figure 6: Internal conditions in the living and sleeping rooms of the “case 2” apartment for the coldest month of a typical year.

Figure 9: Hourly internal conditions in the living room in cases 1 and 2 for the coldest week of a typical year. Daily mean values are also indicated.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

efficient dwelling. It is to share the responsibility between the designer and the inhabitant. Each one’s responsibility is exposed. The designers’ responsibility is about healthy conditions and the quality of heating systems, while inhabitant’s responsibility is about comfort conditions and the proper use of heating systems.

6. FUTURE WORKS Figure 10: Case 1 gains compared with total heat demand and heat supply for the coldest week of a typical year.

for typical meteorological condition. Although, it do not allows to design housing unequipped with heating power. Because the proposed healthy limits are less strict than comfort limits. And because heating power is needed to reach comfortable or healthy indoor conditions, after inoccupation periods or during extremely cold periods. We consider that our results are above all of conceptual use. In northern Europe, heating supply as until now be seen as inevitable. Recently, heating consumptions in buildings where seen as normal but to be reduced in order to face climate change. But full disappearance of this consumption was not hoped for, and an attitude based on their compensation was developed (i.e. “NZEB” concepts). In this context, both heating consumption reduction and renewable energy supply are seen as part of the design team responsibility. Thanks to our results, another vision may rise, based on the sustainability principle of shared responsibility [27]. This principle urges both designers and inhabitants to act at their own level. This paper suggests that the responsibilities of architects and designers may be: 1/ to design the building in order to achieve healthy conditions without heating and 2/ to design an heating system allowing the inhabitant to use it an adequate an efficient way. When living in such a dwelling, the inhabitant responsibilities would be: 1/ to choose living conditions that, although matching his own particular comfort feeling, are as close as possible as the without heating supplied healthy conditions and 2/ to use the heating system in order to create these comfort conditions with the least energy. This idea that the inhabitant has to share responsibility in the buildings environmental performance is consistent with the 2009 Plea manifesto [28].

5. CONCLUSION This paper presents two developments. Healthy temperature and humidity limits are exposed based on a literature survey. Those limits are compared with ASHRAE comfort zones. Dynamical simulation results are presented for a free float running Passive house apartment. It indicates that healthy conditions can be maintained without mechanical heating supply for a typical winter in Belgian, as long as the apartment is inhabited. Based on these results, we propose a conceptual development about the necessity to achieve energy

The survey of medical references should be pursued in order to determine maximal temperature limits. Since comfort limits in summer have been shown to be transient, it may be suspected that health limits will be too. An alternative graphical or numerical expression of health limits that is best suited for transient criterions should then be developed. The ability of Passive House apartments to fulfill these criterions without mechanical cooling should be demonstrated. But since such dwellings have been shown to be comfortable if properly designed [27, 28], this demonstration should be implicit. Other buildings types such as row houses or commercial buildings have to be studied. Finally, this article indicates that the proposed definition of the designers’ responsibility correspond to slightly improved best practices in passive building design. Further development could determine practical and methodological recommendations in order to adapt Passive House recommendations to this new objective.

7. REFERENCES [1] European Parliament, Report on the proposal for a directive of the European Parliament and of the Council on the energy performance of buildings (recast) (COM(2008)0780-C60413/2008-2008/0223(COD)), 2009. [2] P.Hernandez and P.Kenny, From net energy to zero energy buildings: Defining life cycle zero energy buildings (LC-ZEB), Energy and Buildings 42 6 (2010), pp. 815-821 [3] Erik H. Lysen. The Trias Energica: Solar Energy Strategies for Developing Countries. Eurosun Conference, Freiburg, 16-19 Sept 1996. [4] CEPHEUS: Cost efficient Passive Houses as European Standards, A project within the THERMIE Programme of the European Commission, Directorate-General Transport and Energy, Project Number: BU/0127/97, Duration: 1/98 to 12/01, Available from: http://www.cepheus.de [5] Institut Wallon, La consommation électrique d'un ménage URE, 2004 W.Feist, E.Baffia, J.Schnieders, R.Pfluger, O. Kah. Passivhaus Projektierungs Paket 2002, Anforderungen an qualitätsgeprüfte Passivhäuser, 4. Auflage, Fachinformation PHI2002/1, Darmstadt, Passivhaus Institut, January 2002.

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[6] F. Nicol and M.A. Humphreys , Thermal comfort as part of a self-regulating system. Building Research and Practice (Journal of CIB) 6 3 (1973), pp. 191-197 [7] R. deDear and G. Brager , Developing and adaptive model of thermal comfort and preference. ASHRAE Transactions 104 1 (1998), pp. 145-167 [8] M.A. Humphreys, Field studies of thermal comfort compared and applied. Journal of the Institute of Heating and Ventilating Engineers 44 (1976), pp. 5-27 [9] M.A. Humphreys , Outdoor temperatures and comfort indoors. Building Research and Practice (Journal of CIB) 6 2 (1978), pp. 92-105 [10] A. Auliciems and R. deDear, Air conditioning in Australia. I. Human thermal factors. Architectural Science Review 29 (1986), pp. 67-75 [11] American Society of Heating Ventilating and Airconditioning Engineers, ASHRAE Standard 55 2004 -Thermal Environmental Conditions for Human Occupancy (ANSI Approved), Atlanta, USA, 2004 [12] American Society of Heating Ventilating and Airconditioning Engineers, 2005 ASHRAE Handbook – Fundamentals, Atlanta, USA, 2005 [13] B.Boardman, Introduction, in Cutting the cost of cold : affordable warmth for healthier homes, E&F Spon, 2000 [14] P.Wilkinson, M.Landon and S.Stevenson, Housing and winter death: epidemiological evidence, in Cutting the cost of cold : affordable warmth for healthier homes, E&F Spon, 2000 [15] K.Collins, Cold, cold housing and respiratory illnesses, in Cutting the cost of cold: affordable warmth for healthier homes, E&F Spon, 2000 [16] G.Payling-Wright and H.G.Payling-Wright, Etiological factors in bronchopneumonia among infants in London. Journal of hygiene 44 (1945), pp.15-30 [17] T.Oreszczyn, I.Ridley, S.H.Hong and P.Wilkinson, Mould and winter indoor relative humidity in low income households in England, Indoor and Built Environment 15 2 (2006), pp. 125-135 [18] O.Adan, G.Schober, F.M.Kniest and J.Vorenkamp, Changing the indoor humidity conditions, an allergological sanitation method for the indoor environment, Revue Française d'Allergologie et d'Immunologie Clinique 28 2 (1988), pp.147-151 [19] L.G.Arlian, J.S.Neal, M.S.Morgan, D.L. Vyszenski-Moher, C.M.Rapp and A.K. Alexander. Reducing relative humidity is a practical way to control dust mites and their allergens in homes in temperate climates. Journal of Allergy and Clinical Immunology 107 1 (2001), pp.99-104

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[20] L.G.Arlian, J.S. Neal, M.S. Morgan and D.L. Vyszenski-Mohe. Reducing relative humidity to control the house dust mite Dermatophagoides farina. Journal of Allergy and Clinical Immunology 104 4 (1999), pp.852-856 [21] Ib.Andersen and J.Korsgaard, Asthma and the indoor environment: Assessment of the health implications of high indoor air humidity. Environment International 12 1-4 (1986), pp.121-127 [22] S.Howieson and A.Lawson, Dust mite allergens, indoor humidity and asthma, in Cutting the cost of cold : affordable warmth for healthier homes, E&F Spon, 2000 [23] P.Wolkoff and S.K.Kjargaard, The dichotomy of relative humidity on indoor air quality, Environment International 33 6 (2007), pp.850857 [24] J.Goodwinn, Cold stress, circulatory illness and elderly, in Cutting the cost of cold: affordable warmth for healthier homes, E&F Spon, 2000 [25] W.Feist, S.Peper and M.Görg, CEPHEUSProjectinformation No. 36, Final Technical Report, July 2001 [26] United Nations Environment Programme, Rio Declaration on Environment and Development, United Nations Conference on Environment and Development, Rio de Janeiro, 1992 [27] R.J.Cole, Z.Brown, and S.McKay, Building human agency: a timely manifesto, Building Research & Information 38 3 (2010), pp.339-350 [28] J.Schnieders and A.Hermelink, CEPHEUS results: measurements and occupants’ satisfaction provide evidence for Passive Houses being an option for sustainable building, Energy Policy 34 2 (2006), pp.151-171 [29] S.Peper, W.Feist and O.Kah, Meßtechnische Untersuchung und Auswertung; Klimaneutrale Passivhaussiedlung in Hannover-Kronsberg, Fachinformation PHI-2001/6, CEPHEUSProjektinformation Nr. 19, Passivhaus Institut, Darmstadt, 2001

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

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Thermal performance evaluation of four low cost houses in Santa Maria - Brazil Giane GRIGOLETTI1, Renata ROTTA2, Sâmila MULLER1 1

Departamento de Arquitetura e Urbanismo, Universidade Federal de Santa Maria, Santa Maria, Brazil 2 Curso Técnico em Edificações, Instituto Federal Farroupilha, Santa Maria, Brazil

ABSTRACT: Since 2008 in situ measurements for typical Brazilian low cost housing have been taken in order to verify their thermal performance and to propose suitable patterns for them. This paper presents the results corresponding to research stage where four houses located in a medium city in the South of Brazil were evaluated. The houses differ in the constructive system (ceramic and concrete blocks) and in their solar orientation. The aim is verify the thermal performance in accordance to solar orientation and constructive system. Three methods are considered: simulation based on Brazilian standards for transmittance and time delay of walls and roofs, survey and in situ measurements of external and internal temperatures. The survey was applied to thirty seven families. The used tool is a questionnaire about habits and domestic equipments such as stove, fan, and heating. In situ measurements were carried with thermal sensors during the months January and April. The hours of discomfort and degree-hours were analyzed. The three methods indicated the same undesirable thermal behaviour for the four houses. The results reinforce the importance of solar passive heating for winner conditions. In relation to system constructive, the performance of houses did not present significant differences. Keywords: thermal performance evaluation, low cost housing, thermal comfort

1. INTRODUCTION

2. OBJECTIVE AND METHOD

In Brazil low income housing has presented several thermal comfort problems and this kind of housing has been subject of researches and evaluations. Studies based on in situ measurements are very important since they allow the evaluation of thermal performance of housing in real conditions. In the South of Brazil some analysis based on in situ measurements were carried by Becker [1], Grigoletti et al. [2] and Morello et al. [3] among others. The variables monitored by authors include external and internal temperatures and relative humidity. The main conclusions pointed to not satisfaction of thermal comfort conditions defined by Givoni [4]. This paper presents the results obtained for four houses submitted to in situ measurements of internal temperatures during the months February and March 2010. Two houses (A and B) have one bedroom and they are built with ceramic blocks. The two others (C and D) have two bedrooms and are built with concrete blocks. The four houses differ in solar orientation (see Table 2) and they are located in an urban zone (characterized by low density) of a medium sized city in South of Brazil. In 2009 measurements were carried for three similar houses [5] and located in the same city. They were submitted to in situ measurements for 14 days and preliminary results demonstrate that internal air temperatures were very near to external temperatures mainly for the maximum. The measured internal temperatures were above the highest limit comfort zone for developing countries (equal to 29C) according to Givoni [4] and there was not significant difference between internal air temperatures of different rooms in which the measurements were carried.

The research intends to define thermal performance for local housing for the poor, initially considering two possible categories of solutions: appropriate to the local standard and no appropriate. In this step, the behaviour of four houses was evaluated in aim to verify the influence of solar orientation and constructive system elements (walls and roof). The four houses were selected starting from the indication of local government responsible by the project and construction of low cost housing. The government indicated a settlement as a solution no advisable because the houses, along the time, presented problems of thermal comfort according to the occupants' perception. The houses were selected starting from two typologies: one and two bedrooms, ceramic and concrete blocks for walls and asbestos cement and ceramic tiles like illustrated in table 2. The houses were analysed through in situ measurements, Brazilian standards and occupant’s opinion. 2.1. In situ measurements The houses were submitted to in situ measurements during the months February and March, 2010. External and internal air temperatures were registered on an hourly basis. Two sensors were installed in each house (kitchen/living room and bedroom) at approximately 1.9 m above the floor and they were located on southwest (house A), northeast (house B), north (house C) and south (house D). Additionally an external sensor was fixed under the eaves with the aim of measuring the external air temperatures. Measurements extended from January

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PLEA2011 - 27th International Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

30th to April 08th 2010 (1,657 hours). The used equipment was a HOBO Temperature, Rh © Onset 1996. The comfort zone for developing countries according to Givoni [4] is used to analyse de thermal behaviour of housing through the concepts of total hours of discomfort and degree-hours.

Table 2: Characterization of the analyzed houses

2.2. Standard recommendations

House A

The Brazilian standards concern to limits for the wall and roof thermal transmittance (U), time delay () and the external colour of those represented by the solar factor (FS=100%×U×Rse×, where Rse is the external resistence of surface and  is the absortance of surface). The city in question belongs to Bioclimatic Zone 2 that prescribes light walls and roofs (see table 1). Table 1: Brazilian standards for the city of analysed houses

Walls thermal transmittance (W/m².K) Wall thermal delay (hour) Roof thermal transmittance (W/m².K) Roof thermal delay (hour)

BioZone 2 ≤ 3,0 ≤ 4,3 ≤ 2,0 ≤ 3,3

2.3. Occupants’ opinion Additionally 37 occupants of the houses answered to a questionnaire that intended to verify their satisfaction in relation to the thermal comfort, sources of heat inside the housing and habits in the use of the houses among others topics. Topics included in the survey were occupants’ age and how long they have been living in the residence; how long they daily stay at home; if occupants consider the house hot in the summer; if they use fans or other cooling equipment and the period of time they use it; what is the hottest room; what room is more comfortable in the summer; if occupants consider the house cold in the winter; if they use artificial heating and the period of time they use it; what is the coldest room; what room is more comfortable in the winter; if the house is humid.

3. FINDINGS 3.1. Housing description The four analysed houses are located in a urban low density zone. The neighbourhood is characterized by one-store houses isolated in individual plots (without shared walls between them). Table 1 presents the plan floor with the sensors location and the characterization of walls and roofs. 3.2. In situ measurements Figure 1 illustrates respectively internal and external air temperatures for A, B, C and D houses st th from 1 to 15 March. The occupants stayed at home during the days of measurements, except for D house. For A house, bedroom with south-west orientation presents higher internal temperatures than the maximum external temperatures and lowest

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internal temperatures than the minimum registered outdoor. It is indicative of housing low thermal inertia that causes their fast response to external changes of climatic conditions. Other possibility concerns to occupants’ habits such as maintaining the windows open.

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- Wall – white colour, ceramic blocks with mortar plaster in both sides - Roof – grey colour, asbestos tile (6mm thickness) and internal layer of concrete (8cm thickness) House B - Wall – white colour, ceramic blocks with mortar plaster in both sides - Roof – red colour, ceramic tile and internal layer of concrete (8cm thickness) House C - Wall – white colour, concrete blocks (10cm thickness) with mortar plaster in both sides - Roof – grey colour, abestos tile (6mm thickness) and internal layer of light wood House D - Wall – salmon colour, concrete blocks (10cm thickness) with mortar plaster in both sides - Roof – grey colour, abestos tile (6mm thickness) and internal layer of light wood

For B house, with north-east orientation, internal temperatures are higher than the minimum external temperatures. This fact could be explained considering the solar orientation of B house that promotes natural heating and its roof that presents high thermal resistance (ceramic tiles). However

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

maximum internal temperatures are higher than 29°C (limit of comfort zone according to Givoni [4]). In some days registered internal temperatures are higher than 35°C.

For C and D houses internal temperatures are closer to maximum external temperatures than to the minimum temperatures. Also maximum internal temperatures present values above 29°C. The room with west orientation presents temperatures higher than the south orientation. For C house significant differences between north and east orientation was not verified. In addition the medium temperature (MT) and standard deviation (SD) for internal and external temperatures were generated for the period of 1st to 15th March. The table 3 presents the results. The solar orientation also is indicated in the table 5. Table 3: Medium and standard deviation for internal and external temperatures

House

A (SO) B (NE) C (L-O) D (O-L)

Living room MT SD 27.5 2.25 27.2 3.24 27.9 2.58 28.0 3.37

Bedroom MT SD 27.1 3.41 27.2 2.28 27.8 2.91 28.1 3.20

External MT SD 26.7 2.74 25.3 4.34 24.8 3.93 26.7 4.58

Although the medium internal temperatures were lower than 29°C, they were higher than the average external temperatures measured close to houses. The standard deviation reached values higher than 3°C for rooms orientated to Southwest, Northwest (wall) and West. The results indicate that, in addition to poisoning of windows, the heating of walls due their solar orientation (thermal load) must be considered in the distribution of rooms, even for small buildings as the presented in this research. Table 4 presents the discomfort hours for cold and heat verified for A, B, C and D houses. B house presented lower percentage for heat discomfort what could be explained by solar orientation and the higher thermal resistance of its roof. C and D houses presented higher percentage that corroborates the local government agents’ opinion. However C house, with north orientation, presents better performance than the D house. Table 4: Discomfort hours percentage for analysed houses

Houses A B C Discomfort percentage (%) living 34.3% 30.2% 37.1% bedroom 32.6% 28.6% 37.1% living 0.6% 0.8% 0.3% bedroom 2.2% 0.6% 0.7% Room

Heat Cold

Figure 1: Internal and external temperatures for houses st th A, B, C and D respectively from 1 to 15 March

D 38.5% 40.0% 0.5% 0.8%

Table 5 presents the degree-hours DH (number of degrees Celsius by which the hourly internal temperature is respectively above and below the standard temperatures of 29 and 18°C) for analysed houses in the measurements period (two months). The table 5 also presents the mean degree-hours MDH in the same period (degree-hours divided by the numbers of hours where the temperatures were above or below 29°C and 18°C).

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Cooling

Living

Heating

Table 5: Degree-hours and mean degree-hours for analysed houses

Living

Bed

Bed

DH MDH DH MDH DH MDH DH MDH

A 1,222 2.15 1,503 2.77 4 0.44 38 1.02

houses B C 1,318 1,477 2.64 2.54 900 1,600 1.96 2.75 7 0 0.67 0.10 7 20 0.42 2.82

D 1,992 3.12 2,000 3.02 4 0.48 26 2.00

The analysis of degree-hours and mean degreehours indicates A and B houses have better performance for summer conditions (cooling) than the C and D houses. Although cooling degree-hours for A and B are lower, they are more concentrated (mean degree-hours). This behaviour could be related to thermal inertia of them. However C house also presents performance similar to A and B houses for cooling. This behaviour could be related to solar orientation of living room and bedroom (with walls oriented to west and east). Additionally the D house has not been occupied during measurements that influenced its behaviour for summer and winter conditions. For heating the B house (with north-east orientation) did not present difference for degreehours of bedroom and living room. However A, C and D houses presented a significant difference between degree-hours measured for living room and bedroom. Degree-hours for bedrooms are higher than living room. This behaviour could be explained through solar orientation of bedrooms that do not receive solar radiation during afternoons. 3.3. Standard recommendations Thermal properties of wall and Brazilian standards for thermal transmittance, time delay and solar factor are presented on table 6. Thermal transmittance standard references for walls are satisfied for A and B houses, but not for C and D. Time delay and solar factor standard references are satisfied for the four houses, except D house that factor solar is higher than the proposed level.

For the roofs only B house satisfied Brazilian standard for thermal transmittance. Time delay was not satisfied by any houses. The solar factor was satisfied by all houses. However considering the regional climatic conditions suggest that recommendation for time delay could be specified for a minimum value. In other words houses with higher thermal inertia could be desirable since temperatures have significant daily variance. 3.4. Occupants’ opinion The survey was based on a questionnaire with closed questions that include if the occupants consider their houses hot or cold for summer and winter; if they use artificial ventilation or heating; what rooms are more comfortable in summer and winter; if they open the windows during the summer, among others. Table 8 presents the results obtained through the survey. The occupants are very unsatisfied with winter and summer conditions for the four houses. A and B houses presented higher unsatisfied percentage for the winter conditions whereas C and D houses presented higher dissatisfaction for summer conditions and humidity. Table 8: Survey results and occupants’ opinion

Questions

Hot conditions in summer Cold conditions in winter Humidity Artificial ventilation in summer Heating in winter Stay at home during the day

AeB (yes) 71% 86% 43% 100% 29% Yes/yes

CeD (yes) 97% 67% 73% 100% 17% Yes/no

Houses built in concrete blocks presented more problems of humidity than the ones built in ceramic blocks. The high percentages of heating reinforce the unpleasant with winter conditions of A and B houses. Considering the results obtained with the in situ measurements and the occupant’s opinion, the Brazilian standards recommendations do not guarantee an adequate thermal performance and occupant’s comfort.

Table 6: Brazilian standards and thermal properties of wall

Wall prop. U (W/m²K)  (h) FS (%)

Standard ≤ 3,0 ≤ 4,3 ≤ 5,0

A 2,81 3,4 2,20

B 2,81 3,4 2,20

C 4,24 2,4 3,40

D 4,24 2,4 5,10

Thermal properties of roofs and Brazilian standards for thermal transmittance, time delay and solar factor are presented on table 7. Table 7: Brazilian standards and thermal properties of roof

Roof prop. U (W/m²K)  (h) FS (%)

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Standard ≤ 2,0 ≤ 3,3 ≤ 6,5

A 2,17 3,5 5,64

B 2,00 3,5 5,64

C 2,20 3,4 5,72

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D 2,20 3,4 5,72

4. CONCLUSION The findings corroborate the importance of solar orientation of housing and thermal resistance of roof with the proposal to reduce the discomfort caused by hot climate. Additionally local government agents’ opinion, A and B house (ceramic blocks) presented better thermal performance than the C and D (concrete blocks), was confirmed by the results. Concerned to rooms and their degree-hours and mean degree-hours, there was relevant difference between them according to their solar orientation that indicates the importance of solar orientation of rooms as their use by the occupants (daily permanency for a long time). Considering the hours of discomfort,

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

there was no significant difference between them. This result could suggest that degree-hours and mean degree-hours are more indicates for thermal analysis than the hours of discomfort. Brazilian standards could be revised with the proposal of improve the thermal inertia of housing for BioZone 2. The occupants’ opinion indicates a elevate dissatisfaction with analysed typologies. Finally the general results suggest that the standards adopted in Brazil should be more stringent.

5. ACKNOWLEDGEMENTS The authors acknowledge the support of FIPE (Fundo de Incentivo à Pesquisa) of Universidade Federal de Santa Maria for the financial support and the PPGEC/UFSM for material support.

6. REFERENCES [1] Maria de F. M. Becker, Análise do desempenho térmico de uma habitação unifamiliar térrea Dissertação de Mestrado, Porto Alegre (1992). [2] G. Grigoletti, M. A. Sattler, A. Morello, Analysis of thermal behaviour of a low cost, single-family, more sustainable house in Porto Alegre, Brazil. Energy and Buildings 40 (2008) 1961-1971, [3] A. Morello, G. Grigoletti, M. A. Sattler, Analysis of thermal behaviour of a low cost, single-family, housing prototype considering specific climatic conditions, Proc. 23th PLEA, Genève (2006). [4] B. Givoni, Comfort, climate analysis and building design guidelines. Energy and Buildings 18 (1992) 11-23. [5] G. Grigoletti et al., Thermal performance evaluation of low cost in Santa Maria – Brazil, Proc. 26th PLEA, Quebèc (2009).

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Performance of Shading Device in Classrooms of Zero Energy Building in Singapore Nyuk Hien WONG 1, Erna TAN2 1

Department of Building, National University of Singapore, Singapore Department of Building, National University of Singapore, Singapore

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ABSTRACT: Zero Energy Building (ZEB) of Building and Construction Authority (BCA) Academy in Singapore is a retrofitted building with different green building design features and technologies, used as a test-bed for innovative building designs and energy efficient building solutions, especially for existing buildings. The building has air-conditioned office space and naturally ventilated classrooms, with existing building orientation of east and west and main functioning rooms face the west. Several passive design strategies were installed to minimize the impact of the solar radiation from the west and to be more energy efficient. The paper focused on the performance of different configurations of shading device in reducing heat again under afternoon sun for the west facing naturally ventilated classrooms. Field physical measurements were conducted to compare the space with and without the shading device. The study found out that the performance of 4-panel configuration was more efficient than complete setting configuration in reducing heat gain into the building. Keywords: shading device, passive design, heat gain, Zero Energy Building, Singapore

1. INTRODUCTION In tropical climate area with abundant solar radiation throughout the year, shading device is a feature that can shade the building from direct solar radiation and hence, reduce the heat gain and make the space under the shade cooler. The paper discussed the performance of different configurations of shading device in reducing heat gain under afternoon sun for the west facing naturally ventilated classrooms. The heat gain study compared the mean radiant temperature of the room with and without the shading device for 2-panel, 3panel, 4-panel and complete setting configurations. The next section of the paper gave general overview of shading device, and the shading device installed in the classrooms of Zero Energy Building. It was followed by discussion on the method of the physical measurement and the results. Finally, it was closed with conclusions, limitations and future study.

2. LITERATURE REVIEW 2.1. Passive design - shading device According to Ochoa and Capeluto, there has been a growing interest to include intelligence in buildings to be energy-efficient [1]. It can be done by the smart architectural design decisions (passive design strategies) or intelligent technological devices. They defined passive design strategies as strategies in developing a building to respond adequately to the climatic requirements, while active features are elements of buildings which can self-adjust to the changes initiated by the internal or external environments. There are different passive design strategies available for different climate. For tropical climate, the common strategies are to harness the prevailing wind for natural ventilation and the available sunlight

for daylighting, and to prevent heat gain into the building from the excessive solar radiation. One of the passive design strategies is shading device. It is the basic strategy to reduce the temperature build-up due to ambient air or solar incidence [2]. There are different types of shading device. Horizontal overhang is more efficient to shade from high sun angles, while vertical fin and parallel-to-thewall screen are more efficient for lower sun angles [3]. 2.2. Singapore climate Singapore is located at North 1.3° and East 103.8°. The climate is hot and humid with uniform high temperatures, humidity and rainfall throughout the year. The diurnal temperature variations are small, minimum of 23°C to 26°C and maximum 31° C to 34°C [4]. (Fig. 1) shows the sun path diagram of Singapore. The sun rises at around 07:00 in the east, travels quite symmetrically along the North/South and East/West axes, reaching the peak altitude at around 13:00 and sets in the west at around 19:00. There are two monsoons in Singapore. The Northeast Monsoon occurs between November and March with the prevailing wind blows from North to Northeast, The Southwest Monsoon occurs between June and September with the prevailing wind from South to Southwest. The sun rises at around 7am reaching the peak altitude at around 1pm and sets at around 7pm. Throughout the year as the earth rotates and orbits around the sun, the sun is above the equator on 21 March and 23 September, travels southern during 23 September to 21 December and northern during 21 March to 21 June [5].

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wall. Hence, the maximum depth of shading is 1200mm. (Figs. 2, 3, 4 and 5) show the 2-panel configuration, 3-panel configuration, 4-panel configuration and complete setting configuration of the shading device respectively.

  Figure 1: Sun path diagram of Singapore

Figure 2: The 2-panel configuration of shading device

2.3. Shading device in Zero Energy Building Zero Energy Building (ZEB) is a retrofitted existing building in the Building and Construction Authority (BCA) Academy, Singapore. It is also the first of such building in Southeast Asia and fully retrofitted with green building design features and technologies. It is used as a test-bed for innovative building designs and energy efficient building solutions [6]. The block of ZEB is facing East and West. One third of the ZEB block was retrofitted into naturally ventilated classrooms. It covers two structural grids of the three storey high building. There are two classrooms each and common area on 1st storey and nd rd 2 storey, and a school hall on 3 storey. All classrooms and school hall have windows on the west facade which receive direct solar radiation, while the east side open to shaded common area or corridor. st On the 1 storey facade, there were modular shading devices installed, which configuration can be changed. On the 2nd storey, there were lightshelves installed. On the 3rd storey, there were permanent shading devices installed.

3. METHODOLOGY

  Figure 3: The 3-panel configuration of shading device

  Figure 4: The 4-panel configuration of shading device

3.1. Weather condition There was weather station installed for the ZEB block, providing the data of ambient solar irradiance, wind velocity and air temperature. This sensor was installed on the open air of the roof without any shade. The solar irradiance data was used as a guide to choose clearer day for analysis. There were also pyranometers installed on the west facade of the classrooms to measure the actual solar irradiance exposure that reached the rooms used for the comparison study. 3.2. Shading device A horizontal and vertical system of shading device was used for study. Modular panels of 300mm width each were made. Each system can hold up to 4 horizontal panels, 4 vertical panels on each side, and a vertical panel parallel to the facade

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  Figure 5: The complete setting configuration of shading device

The paper studied different configurations of 2 horizontal panels (600mm depth), 3 horizontal panels (900mm depth), 4 horizontal panels (1200mm depth), and complete setting. (Fig. 6) shows the complete setting configuration of the shading device

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

irradiance was at around 2pm when the sun was at high altitude and the solar radiation went through between the trees and the building facade. It dropped at between 3pm to 4pm when the solar radiation was blocked by the tree canopy and increased at 5pm as the solar radiation went below the canopy. The graphs of mean radiant temperature of 2panel, 3-panel, 4-panel, and complete setting configurations between shaded and non-shaded zones from 7am to 7pm were shown in (Fig. 7) until (Fig. 10) respectively.

  Figure 6: The shading device on the west facade of 1 storey classrooms.

st

3.3. Indoor measurement The objective of the indoor measurements was to determine the heat gain through the difference of mean radiant temperature under different configurations. Globe thermometer was used for continuous measurement to measure the mean radiant temperature. The room was divided into two zones of equal size. Each zone has similar opening on the west facade. One zone has no shading and the other zone has shading depending on the configuration. For each zone, a globe thermometer was located at 200mm away from the middle of the west facade windows and another at 1000mm away. At one time, the measurement was conducted for one zone without any shading and one zone with one configuration of shading device. Hence, the measurement was done on different days for different configurations.

  Figure 7: Mean radiant temperature of 2-panel configuration of shading device.

3.4. Data analysis method The analysis was started by finding the clearer day for each configuration measurement through the weather station’s ambient solar irradiance data. In general, the day with high ambient solar irradiance in the afternoon was used. The west facade solar irradiance was also evaluated to make sure the amount and time of solar exposure for different configurations were similar. Mean radiant temperature of shaded and nonshaded zones of 200mm away and 1000mm away from the west facade windows for each configuration were plotted into graph. The readings were compared among the different configurations, and between the shaded and non-shaded zones.

Figure 8: Mean radiant temperature of 3-panel configuration of shading device.

4. RESULTS AND DISCUSSIONS A brief analysis on the ambient and the west facade solar irradiance data was conducted. It was found that the west facade solar irradiance profile started to follow the ambient solar irradiance profile at 1pm. Therefore, the analysis was based on afternoon data from 1pm-7pm. Through this analysis, it was also found that the irradiance on the west facade was much affected by the shading from the trees in front of the west facade and the roof of the building. The peak of the

Figure 9: Mean radiant temperature of 4-panel configuration of shading device.

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From all the readings, the 4-panel and the complete setting configurations showed the best performance in reducing the heat gain into the building. Comparing from the construction cost and effort, it could be inferred that the 4-panel configuration was more efficient to reduce the heat gain than the complete setting configuration.

5. CONCLUSION

Figure 10: Mean radiant temperature of complete setting configuration of shading device.

In general, the mean radiant temperature profile for 2-panel configuration was similar to 3-panel configuration, and the profile for 4-panel configuration was similar to complete setting configuration. At 200mm away from the west facade windows, at the peak time around 3pm, the reduction of mean radiant temperature between the shaded and nonshaded zones of the 2-panel and the 3-panel configurations in average was less than 1°C, while for the 4-panel configuration was around 1°C, and for complete setting configuration was around 2°C-3°C. At the peak time around 3pm, there was high difference between the shaded and the non-shaded zones, i.e. 2-panel configuration and 3-panel were around 9°C, and 4-panel configuration was around 8°C. The high difference was caused by the nonshaded zone’s 200mm away from the west facade windows’ globe thermometer’s direct exposure to the solar radiation at the peak time. At 1000mm away from the west facade windows, the 2-panel, 3-panel and 4-panel configurations showed similar difference of shaded and non-shaded zones, i.e. around 1°C-2°C. The complete setting configuration showed 2°C-4°C difference. At peak time, the difference was not as high as the reading from 200mm away from the west facade windows as the globe thermometers were not directly exposed to the solar radiation. For non-shaded zone at 200mm away from the west facade windows, the 2-panel and 3-panel configurations showed around 2°C higher than the 4panel and complete setting configurations. For shaded zone at 200mm away from the west facade windows, the difference is around 1°C-2°C. For non-shaded zone at 1000mm away from the west facade windows, the difference was around 1°C-3°C. For shaded zone at 1000mm away from the west facade windows, the difference was around 1°C. From all the readings available, it could be concluded that 2-panel and 3-panel did not have significant difference and either did 4-panel and complete setting configurations. The difference at 200mm away from the west facade windows was more than that at 1000mm away from the west facade windows.

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The study showed that shading device can reduce the heat gain into the room. The reduction among different configurations was not significant due to the shade from the trees on the west facade. In general, the 2-panel and 3-panel configurations were quite similar, while the 4-panel configuration was similar to the complete setting configuration. From all the readings available, it can be concluded that the 4-panel configuration was more efficient in reducing the heat gain than the complete setting configuration. The reduction between the shaded and nonshaded zone expected in the study was not very high as the shaded zone received more solar radiation than the non-shaded zone due to the shade of the trees on the west facade. Study of the mean radiant temperature at the center of the room is proposed to have better understanding on the impact of the shading device deeper in the room. Study of the difference in illuminance level due to the use of different configurations of shading device is also proposed to achieve an integrated evaluation.

6. ACKNOWLEDGEMENTS This research is supported by Singapore Ministry of National Development (MND) research fund, Singapore Building and Construction Authority (BCA), and Department of Building, National University of Singapore.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

7. REFERENCES [1] Ochoa, Carlos Ernesto and Capeluto, Isaac Guedi, 2008. Strategic decision-making for intelligent buildings: Comparative impact of passive design strategies and active features in a hot climate. Building and Environment, 43, 1829-1839. [2] Wright, David, 1984. Natural Solar Architecture: rd The Passive Solar Primer. 3 ed. New York: Van Nostrand Reinhold Company. [3] Rumbarger, Janet, 2003. Architectural Graphic Standards for Residential Construction. New York: John Wiley and Sons. [4] Jusuf, Steve Kardinal., (in press) Development of estate level urban climatic mapping framework for air temperature prediction in Singapore. Singapore: National University of Singapore. [5] Gaisma, 2010. Sunrise, sunset, dawn and dusk times around the world! [online] Available at:< http://www.gaisma.com/en/location /singapore.html> [Accessed 8 April 2010]. [6] Ministry of National Development, 2009. Zero Energy Building Unveiled! Available at:http://www.mnd.gov.sg/MNDLink/2009/2009_ Nov/BCA_article.htm [Accessed 8 April 2010]

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                                                                                     

                                                                                                                                              

                                                                  

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                                                                                                                                                                                                                                                                     

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BUILDING PHYSIC (HYGROTHERMIC AND ACOUSTIC)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                              

                         

                                            

  

                                                                                                                                                                        

716

BUILDING PHYSIC (HYGROTHERMIC AND ACOUSTIC)

                                    

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  •  •    •  • •  •    •  •  • •  •    •  •  • •  •    •  •  •                                          

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                 

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 • • • • • •   •   

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                                                      

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

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

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

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







 



 

 







 





  

 

                                     

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





 

 











                   

                              





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





   



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    

















 

                                       

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BUILDING PHYSIC (HYGROTHERMIC AND ACOUSTIC)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

 

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      





 

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     

 





 

   















 



















 

 

                                                                           

                                       

     











 







     







 



















 



    

















 

                                                                                    

718

BUILDING PHYSIC (HYGROTHERMIC AND ACOUSTIC)

                                                                                             

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

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      







                            

      

















 

                                  



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    





 











 

  











 



      















 

                                                                      

                                                                                                                                                                                                              

                     

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BUILDING PHYSIC (HYGROTHERMIC AND ACOUSTIC)

719

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Delayed gratification: Interseasonal heat storage, as a carbon-neutral refurbishment strategy for 19th Century dwellings. Greg KEEFFE 1, 1

Leeds School of Architecture, Landscape and Design

ABSTRACT: In the UK there are nearly five million terraced houses, that were built in the nineteenth century. The houses allthough robust and popular perform poorly from an energy point of view. This Paper describes an ambitious project to develop a carbon neutral refurbishment strategy for these houses without massive aesthetic change.. Taking a case study of one archetypal terrace, the project aims to show that, by using PV-thermal panels coupled with an interseasonal store housed in the redundant basement space, a carbon neutral in use solution can be found. The approach adopted minimises the disturbance to existing tenants by focusing on collecting, storing and saving energy all outside the habitable shell and improving the efficiency of that shell from the outside. This approach potentially offers huge savings in the otherwise unnecessary costs of decanting tenants and storing furniture, replacing kitchens, bathrooms and redecoration. Planning issues are minimised by proposing very little change to the front elevation in the context of a uniform street appearance The project incorporates several innovative features, firstly, the project uses a large area of PV-T panels. These produce not only electrical output but also thermal output.The panels chosen are ones with a glazed cover that improve their thermal performance (with a small loss of electrical efficiency). Over the year, the panels produce enough thermal energy to heat the property and enough electricity to power it. Secondly the project utilises an interseasonal store in the cellar of the property. The key idea is to store energy from the summer and autumn and use this to supplement the winter output of the panels to provide thermal output that matches the heating needs of the property. Finally, there are fabric improvements to lower the heat loss of the house. The project shows that, with minimal intervention to the fabric and aesthetic of the dwelling, it is possible to produce a robust, carbon-neutral in use solution, that is applicable to a large number of Victorian dwellings.

Keywords: carbon neutral, inter-seasonal store, pv-t, terrace

1. INTRODUCTION In the UK there are nearly five million terraced houses, that were built in the nineteenth century [1]. The houses allthough robust and popular, perform poorly from an energy point of view. This paper describes an ambitious project to develop a carbon neutral refurbishment strategy for these houses without massive aesthetic change. Taking a case study of one archetypal terrace, the project aims to show that, by using PV-thermal panels coupled with an interseasonal store housed in the redundant basement space, a carbon neutral in use solution can be found. The approach adopted minimises the disturbance to existing tenants by focusing on collecting, storing and saving energy all outside the habitable shell and improving the efficiency of that shell from the outside. This approach potentially offers huge savings in the otherwise unnecessary costs of decanting tenants and storing

furniture, replacing kitchens, bathrooms and redecoration. Planning issues are minimised by proposing very little change to the front elevation in the context of a uniform street appearance The project incorporates several innovative features, firstly, the project uses a large area of PV-T panels. These produce not only electrical output but also thermal output.The panels chosen are ones with a glazed cover that improve their thermal performance (with a small loss of electrical efficiency). Over the year, the panels produce enough thermal energy to heat the property and enough electricity to power it. Secondly the project utilises an interseasonal store in the cellar of the property. The key idea is to store energy from the summer and autumn and use this to supplement the winter output of the panels to provide thermal output that matches the heating needs of the property. Finally, there are fabric improvements to lower the heat loss of the house.

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The project shows that, with minimal intervention to the fabric and aesthetic of the dwelling, it is possible to produce a robust, carbon-neutral in use solution, that is applicable to a large number of Victorian dwellings. 1.1.

1.2. The House.

Project brief

The system devised uses two innovative technologies, and a series of simple heatloss measures to provide a true energy-neutral solution to renovation, which is highly replicable, can be completed in a very short length of time, and without decanting the occupier of the house. This is achieved, by the development of a system that stores summer heat, in an underground store, to be used in the winter months. The approach adopted will minimise the disturbance to existing tenants by focusing on collecting, storing and saving energy all outside the habitable shell and improving the efficiency of that shell from the outside. This approach potentially offers huge savings in the otherwise unnecessary costs of decanting tenants and storing furniture, replacing kitchens, bathrooms and other fittings and redecoration. The proposal can be applied to one-off properties or even more efficiently to grouped properties. Planning issues are minimised by proposing very little change to the front elevation in the context of a uniform street appearance. Whole terrace retrofits could propose more radical aesthetic transformation with greater energy efficiency.

Figure 1: Typical Victorian terrace circa 1880.

The Property is situated in Salford, Manchester UK. It is a 3-bedroom, Victorian mid-terrace with single-storey, front bay-window, two-storey rear outrigger and cellars. It is typical of the type with solid brickwork construction and slated roof on timber rafters and purlins. Ground and first floors are suspended timber construction, except for the rear kitchen which appears to be ground bearing concrete. There are brickwork chimneys to all main rooms and cellars. There is a small rear garden accessible from a rear alleyway, and a small front garden. Car parking is all on-street.

The project had to satisfy the demands of the ‘real world’ in order to be sustainable in use and priorities have been set to utilise methods which will: ¥ have the least possible disruption to the lifestyle of existing occupiers and have the simplest control systems ¥ have the least possible disruption to residents during refurbishment works (although they will decant for this prototype) ¥ be carbon neutral in use ¥ be effective when applied to an individual house or a whole street ¥ have long life expectation and low maintenance requirements ¥ build on and reinforce the qualities of the existing building fabric ¥ make little visual impact to the property and the character of the street ¥ not impinge on the internal dimensions and features of the rooms ¥ minimise internal work to main living areas.

 

Figure 2: Plan of house

The house type is typical of thousands owned by Great Places Housing Association and whilst it is a typical 'northern terrace', the main features are applicable to millions of houses around the UK. The existing house is very thermally inefficient, as seen below in Table 1.

   

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 1: Elemental U-values before and after refurbishment Element Wall Floor Roof Window Airchange rate Heatloss parameter

Existing U-value (W/m2/K) 2.0 2.1 0.5 5.9 1.5 ach

Renovated U-value (W/m2/K) 2.0 front 0.24 rear 0.15 0.11 0.9 0.45 ach

3.55 W/m2/K

1.17 W/m2/K Figure 3 Sectional GRP tank

2. STRATEGIES FOR CARBONNEUTRALITY 2.1. Solar Thermal and electric. The system comprises a roof-mounted array of Zen Solar Twin PV-T panels. These panels are an innovative design comprising a standard PV panel inside a glass fronted insulated box, combined with a copper pipe water collect affixed to the back of the panel. This design utilises more than 75% of solar energy that falls on the panel. Over the year, the panels produce enough thermal energy to heat the property and enough electricity to power it. The overall energy yield is approximately 40% greater than separate PV and Solar Thermal panels could provide over the same area. Over the year, the panels will produce enough thermal energy to heat the property and enough electricity to power it (with small changes to the fabric and use of a feed-in-tariff). Calculation shows that the panels insitu should produce some 1276kWh/a electricity and 4278kWh/a usable heat.

2.2. Interseasonal store. The project utilises a previously untried interseasonal store in the cellar of the property. The main problem with solar water space heating is that when heat is needed for space heating, there is very little output from the panel. Our design solves this problem by storing the excess thermal output of the panel in summer in a large water store situated in the cellar rooms of the property and then uses this to supplement the winter output of the panels to provide thermal output that matches the heating needs of the property. The design utilises the largest store physically capable of being installed in the cellar. A pair of sectional GRP tanks are assembled in the cellar, and fully insulated with 500mm of rigid and beaded insulation, these are then filled with water. The total capacity of the tank(s) is around 23 m3 of water, and they are capable of storing some 3.03GJ of energy.

Figure 4: PV-T panels capable of producing not only electrical energy but also thermal output

The tank itself is self-supporting and puts no load on the party walls, its only load is on the floor of the cellar. This is considered sustainable as the extra load on the floor will help to maintain the structural stability of the party walls that support the floors and walls. The tanks can be filled directly from the mains over the course of a day, additives can be added to limit biological growth, but it is unlikely these will be needed. If the neoprene bag was used – there would be no need for venting, but with the sectional tank, venting is solved using a feed and expansion tank in the attic. The rest of the heating system is unchanged: using the existing radiator system, with an improved envelope allows the use of a lower water temp to maintain comfort which works well with the interseasonal store. The GRP Hot Water Tanks are manufactured locally in Stockport by Drayton Tank & Accessories Ltd. An off-the-shelf sectional tank technology has been used for the prototype but this suffers the risk of seals & joints failing. With the prospect of a larger roll-out, there is the incentive for innovation in finding a suitable seamless tank which can be delivered and installed where there is confined access and to suit more bespoke dimensions – possibly a thermosetting polyurethane liner on an insulated back that would incorporate restraining hoops.

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2.3. Careful control of fabric losses. The two thermal components above, at maximum size create a heatloss target for the house. This target has then been met through careful choice of insulation and airtightnesss methods, commensurate with the need to allow the tenant to stay in situ, and the need to maintain the aesthetic qualities of this historic house type, both inside and out. These include triple glazing; insulation to roofs and floors, external insulation of rear façade, and general airtightness strategies such as floor and ceiling sealing, chimney blocking, and heat recovery extract fans.

 

maintain performance at the expected temperatures and can be fully removed in emergency (laid unbonded). This project demonstrates a new use for the ecobead which is usually injected to provide cavity wall insulation.

 

3. INTER-SEASONAL STORE DESIGN The store size was calculated using a custom spreadsheet authored by the team. The spreadsheet uses actual degree day data for Manchester Airport to create a demand profile for the house, and this then compared with the monthly thermal output of the proposed PV-T array, to give a nett positive or negative gain to the store. The store can then be sized according to the cumulative aggregate of energy needed from the store throughout the winter period.

 

  Figure 5: Diagram showing integration strategy for Victorian terrace.

2.4. Heat Loss Reduction Windows - Replacement high performance, tripleglazed windows (U-value 0.9) are used throughout from the Eco-Contract Window Range - supplied and assembled by Green Building Store in Huddersfield. Theses are FSC certified and made with engineered timber components manufactured in Latvia, and glass from the UK. Rear Walls - The rear walls are externally insulated and rendered (U-value 0.24) Roof/Ceiling - High level of insulation is installed to gain a U-value of 0.11 W/m2/K with improvements also to bay roofs Airtightness - This is improved by the installation of the windows, sealing of chimneys and also an attention to detail such as suspended floor junctions, new loft hatch, careful filling of any extant cracking internally, etc; as much as possible with the tenants insitu. Platinum EcoBead loose fill insulation round hot water tanks - loose fill insulation is from Expanded Polystyrene (EPS) with a graphite based constituant which improves its k-value to 0.033W/mK (compared to 0.04W/mK for standard EPS beads). It is a breathable insulant, Green Guide A-rated, will

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  Figure 6: Graph of monthly thermal energy requirement versus energy collected

There are four months (Nov, Dec, Jan, Feb), when the store has to contribute to the panels' output to heat the house. This energy must be stored in the tank before the winter period starts, and thus the volume of the tank is calculated from this need. In addition, over time there will be heatloss from the large store, although this will be small as there is 500mm of mix of u/f and polystrene insulation, around the tank. The tank losses are then aggregated over the period, using a degree-day calculation. (This is a relatively unknown quantity, because much of the heat willl probably find its way into the house - but the asssumptions seem reasonable). The size of the tank is then aggregated from these two figures. The calculations show that for the design the shortfall of energy in the winter months is approximately 3GJ. In order to store this, the interseasonal store needs to be around 22.5 m3 of water, and this can easily be accommodated in the two rooms of the cellar, even with the extensive perimeter insulation.

       

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

removal of one would make the project impracticable, from a carbon neutrality point of view.

Table 2: Interseasonal store tank sizing

The house strategy is developed around three factors, that are the limits for the project. The first is the orientation of the house: in the demonstration case the front of the house is almost perfectly South (within 5 degrees). The second is the size of the PV-T panels on the South -facing roof of the property. 2 x 2800 Solar Twin Panels and 2 x 4200 Solar twin panels are the maximum possible for the roof of the house , taking into account flashing detail and overshadowing by the chimneys. the active area of the panels is some 14.2m2.

Over the winter the tank will be depleted and its temperature will fall from 70 to 35 deg C. It is presumed however, that stratification in the tank will allow the flow temperature from the tank, not to reduce below 65 degC, even at the end of the season, and as the ouput from the panels is prioritised to DHW, the lower temperature in the store should not reduce performance unduly. The use of the existing radiator system mean that itis oversized for the new heatloss of the buildings, and should be able to be run at lower flow temperatures, as the larger emitters, should help to keep radiant levels in the house comfortable.

The final factor is the size of the interseasonal heat store accomodated in the cellar. This is fabricated using a grp sectional system, which was chosen because can be carried easily down the cellar steps, which are situated in the dwelling. This method of tank construction needs 500mm of space for assembly around the sides and top of the tank. This space is subsequently used for insulating the tanks. There are two chambers to the cellar in this type of house, and this limits the store to a max capacity of 22.5 m3 of water. The cost of this tank as a one-off is excessive, but this could easily be reduced by mass-production in the future. Overall, the figures show carbon-neutral performance, that equates to a saving 3.46 tonnes of CO2 per annum, and a tenant saving of £640 in fuel. Calculation of the saving per element in the strategy is difficult as they are all linked but a reasonable assessment is as follows:

 

Table 3: Design assessment re. CO2 Element

4. EVALUATION The thermal performance of the house was assessed using the UK’s Building Research Establishment’s Standard Assessment procedure [2], which use a modified degree-day method, tied with statisical information to provide an annual energy use and Carbon rating. The equivalent numbers calculated with SAP 2005 are: Space Heating Demand Whole House Primary Energy Demand House space heating demand Overall CO2 Target Range

21.7 kWh/m2/yr 15.7 kWh/m2/yr 1814 kWh/yr -1.7 kg/m2/yr

This shows that the house should be carbon negative in use- generating more energy than it needs. The total carbon saving over the existing house is 5667kg of CO2 per annum. The strategy employed is a whole house strategy, with the PV-T panels, interseasonal thermal store and heatloss reduction measures, working together. It is difficult to separate out various features, as the

Usable Thermal energy from PV-T Electrical energy from PV-T Total for PV-T

Energy saved kWh/a

Conversion kg/CO2/kWh

Amount of CO2 saved Kg/annum

1426

0.194

276.6

1276

0.420

535.9 812.5

 

Interseasonal store energy saved Fabric measures

 

842

0.19

163.3

12810

0.194

2485.2

The fabric measures do well in this assessment, due to the terrible thermal performance of the house at present, which is 3.55W/m2/K. The fabric modifications reduce this to 1.17W/m2/K, which is comparable with houses built today to the current UK Regulations. The energy then needed to heat and power the house is provided by the panels, inconjunction with the store.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

5. CONCLUSION There are range of issues regarding large-scale replication of the project. 5.1. Size and orientation of collector space - differing collection potential and efficiency will impact on the size of storage required to supplement meagre winter collection rates. South facing is ideal but panels can work to 85% efficiency facing East or West. Map-based analysis of a typical victorian neighbourhood showed that 75% of the properties had suitable orientation of a reasonable area of roof. Of the other 25%, all could be made to work – with more than one array on less appropriately oriented roofs.

and its replicability. Only detailed monitoring will give accurate results re buildability and reliability. The project is due to go on site in Spring 2011, with completion due in June 2011, in time for the summer charge up of the store. Monitoring of the project will run for 2 full years from completion of building works and will include all tests and monitoring required by the Technology Strategy Board for the Retrofit for the Future fund.

 

6. ACKNOWLEDGEMENTS The author wishes to thank Ian McHugh of Triangle Architects, and Jim McMillan of Great Places Housing Association, for their help in the project.

5.2. Interseasonal heat storage tank size, and integration

7. REFERENCES

In the project the cellar was used to accommodate the store. Surveys by Residential Social Landlords estimate that around 70% of Victorian terraces in Manchester and Salford have cellars. Properties without cellars could utilise the garden to locate a storage tank, indeed grouped properties could utilise communal systems.

[1] The Commission for Architecture and the Built Environment. Housing Market Renewal: Action Plan. HMSO, London. June 2008. [2] SAP 2005, The Government’s Standard Assessment Procedure for Energy Rating of Dwellings 2005 edition, Revision 3. [3] Ofgem. Introducing the feed-in tariff scheme. HMSO, London. April 2010.

5.3. Thermal fabric improvements The thermal improvements were limited to those that could be performed without removing the resident, and without resort to mechnical ventilation. The aim of the project has been met. Further thermal reductions are possible, but not with the tenant in-situ. 5.4. Cost reduction. The two most expensive elements of the cost plan are the PV-Twin panels and the GRP hot water storage tanks. Since these are both generic solutions, it is anticipated that when the system can be shown to be effective, a more industrial scale of production and competitiveness would stimulate reduced prices and alternative manufacturers. The cost of the project, including design fees and enabling works will be in the region of £120,000. Undertaking works to a group of properties would also reduce construction and design costs significantly. Recently feed-in tarriffs for renewably-produced electricity have been introduced in the UK[3], these offer a garranteed return of £0.41 (0.5 Euro) per kWh generated, index-linked for 25years, which for this scheme, producing 1276kWh/a gives a return of £530 per annum. This will also help to make the design more cost effective 5.5. Replication The scheme is a prototype for a proposed roll out over up to 4 million UK homes. There are still a range of issues unresolved regarding its performance

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Residential Buildings with Green Walls Advantages, Disadvantages and Symbols Evoked by the Use of Ficus pumila and Parthenocissus tricuspidata Species Mariene VALESAN, Beatriz FEDRIZZI, Miguel Aloysio SATTLER Programa de Pós-Graduação em Engenharia Civil / NORIE, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil ABSTRACT: The aim of this paper is to analyze the most common species of green walls in Porto Alegre (a city in the south of Brazil): Ficus pumila and Parthenocissus tricuspidata (both self-clinging climbers), based on the perception of 52 dwellers of residences with this vegetation. The in-depth interviews confirmed as being the main advantages of both species: the aesthetic improvement on the landscape, the integration between urban environment and nature, the positive effects for well-being and the positive influence on environmental comfort. The majority of dwellers associated the analysed green walls with positive symbols – beauty, contact with nature, well-being – supporting researches on biophilia, which claims that human beings have a genetic predisposition to answer positively to vegetation. Contrary to popular belief, the association between biophobia and green wall is infrequent among those interviewed. Just 10% of the interviewees tend to reject green walls due to possible presence of bugs and spiders. Ficus pumila is the most recurrent species, however, its vigorous growth and intense demand for maintenance makes its use more difficult. Conversely, Parthenocissus tricuspidata seems to be best accepted among interviewees. Keywords: Green Wall; Environmental Perception; Vegetation; Buildings.

1. INTRODUCTION Vegetation is one of the most effective possibilities to incorporate sustainable practices in the cities, due to its capability of improving the quality of the air, reducing the levels of carbon emissions and influencing positively the thermal conditions of buildings [1, 2]. Biophilia, according to Ulrich [3] is a group of positive reactions that human beings have when they are in contact with natural elements which were important in the past, due to their relation to our primary needs, such as food, water and security. On the other hand, biophobia is defined as a genetic predisposition to immediately associate strong fears and aversive reactions, based on negative exposure or information, to some natural stimuli which possibly were threatening during the evolution of humans [3]. The most common human fears are related to snakes, spiders, heights, closed spaces and blood. Despite the fact that recent large-scale transformation in humans’ habitat (after natural settings and now industrialized places) eliminated the real dangers related to fears and phobias, these feelings persist [3]. One of the possible uses of vegetation in urban environment is the green wall (vegetation covering façades of a building, a wall or another vertical element). This paper aims to analyze green walls of residential buildings in Porto Alegre (a city in the south of Brazil), based on the environmental perception of their dwellers, comparing the two most common species: Ficus pumila and Parthenocissus tricuspidata. We also examined the symbols evoked by green walls on humans and the possible relation among this covering and biophilia and biophobia concepts.

2. GREEN WALLS 2.1. Definition According to Dunnett and Kingsbury [4], the green wall is the covering of walls or other vertical elements with vegetation, through a self-clinging mechanism or with the aid of supports, which can be rooted in soil or some sort of growing medium at the base of the wall. Green walls could be classified in two different types: self-clinging and those that need support. Self-clinging green walls are those climbers that have the ability of attaching to surfaces using aerial roots or sticky-tipped tendrils. The most common self-clinging species in the south of Brazil are: Ficus pumila L. (Moraceae), Hedera helix L. (Araliaceae) and Parthenocissus tricuspidata (Siebold & Zucc.) Planch. (Vitaceae). Ficus pumila is a species with origin in eastern Asia. It is popularly known as climbing fig and creeping fig (figure 1). This species have a vigorous growth and uses aerial roots to attach to surfaces [5, 6]. There is a botanical phenomenon, called heterophylly, related to this species. Due to this phenomenon, it is possible to identify two different features in Ficus pumila: the young form (in which the plant have herbaceous branches and small leaves) and the mature form (in which branches are woody and with little adherence, leaves are larger and fruits, similar to edible figs, are produced) [7].

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Figure 1: Example of a Ficus pumila green wall.

Parthenocissus tricuspidata is another selfclinging species, popular named as Boston ivy or Japanese ivy, originated from Japan and China (figure 2). This deciduous species has sticky-tipped tendrils, which are responsible for its adhesiveness [5, 6]. Its leaves are trifoliate, shining green colored and in variable size. In regions of temperate climate, its leaves acquire a crimson color in autumn before falling [5, 8].

as green walls can be beneficial to wildlife [11] because many of these species provide shelter for birds and its nests and also hibernation sites for insects [4, 9]. Contrary to popular belief, green walls act as a barrier against excessive humidity in winter, because their leaves avoid rain water from reaching the masonry [4, 13]. Analyzing possible deterioration caused by vegetation in walls, Johnston and Newton [13] affirm that, in fact, the layer of vegetation protects the masonry. Due to the protection created by green walls, the deterioration of masonry is slower than if exposed to heavy rainfall, hail, ultraviolet light and abrupt changes in the temperature [4, 11]. The green wall also acts as an insulator for indoor spaces because a layer of air is created between the masonry and the foliage. This layer involves the buildings and is capable of reducing the energy demand to either warming or cooling indoor locations [1, 11]. McPherson, Simpson and Livingston [14] indicate a 20% savings of energy in buildings covered by vegetation. Cantuária [15] calculates a reduction of up to 50% in the air conditioning cost of a building, when comparing a indoor temperatures of a building with green walls and a similar one without green walls. It is also known that the temperatures of a masonry covered by vegetation are perceptibly lower than the temperatures of an exposed masonry, due to the effect of the vegetation in reducing the heat gains of the building [1, 16]. 2.3. Disadvantages

Figure 2: Example of a Parthenocissus tricuspidata green wall.

Köhler [9] explains that there is a long-term tradition in using ornamental plants on buildings and the use of green walls is a well established practice, mainly in Europe. Big cities, such as London, Seattle and Toronto have established policies to motivate the adoption of green walls, green roofs and vegetation in general. As a result this increases vegetated surfaces and reduce the environmental impact in the urban areas [1, 10, 11]. 2.2. Advantages Green walls are an excellent solution to improving urban spaces with vegetation, mainly those where planting trees are impossible due to the lack of space. The attractive variation throughout the year on the aspect of some species of green walls creates a more interesting landscape to users and population [1, 12]. Similar to trees, green walls can capture airborne pollutants, retaining them on the surface of the plant and preventing them from floating in the atmosphere [1, 9]. In addition to this, heavy metals concentrated in rainwater and carbon dioxide can be assimilated by green walls [4, 11]. The climbers generally used

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The main disadvantages of green walls can be explained by problems in their design or in their planting process [4, 11]. In addition, a poor-quality mortar render can cause damages to the surfaces, even if vegetation and supports are appropriated. Insufficient maintenance can also result in abnormal growth or in undesired vegetation covering elements, such as windows and gutters. 2.4. Maintenance Regular maintenance is essential to a successful green wall. Dunnett and Kingsbury [4] emphasize the importance of the pruning of shoots spreading in undesirable directions as the main care for selfclinging plants.

3. METHOD This paper is part of a MSc dissertation [17], developed during 2008 and 2009. It analyzed the environmental perception of dwellers of buildings with green walls, with the aim of identifying its main characteristics and acceptance. The sample for research was defined by the allowance, or not, by dwellers, to acess the building and by their acceptance to participate in the research. The method used was a series of in-depth tape-recorded interviews, in which a structured questionnaire was applied. This structured questionnaire contained 10 open questions and 10 closed questions, divided into themed groups (satisfaction of dweller and

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

characterization of green walls). The closed questions investigated the perceived influence of green walls in environmental comfort (summer and winter indoor temperature, thermal and acoustical insulation, humidity, animal presence, maintenance and aesthetics). After the interviews, their recordings were transcribed and, afterwards, the analysis of the answers was conducted according to Bardin recommendations [18].

4. RESULTS A total of 49 residential buildings with green walls in at least one of its façades were identified in Porto Alegre: 7 were collective residences (buildings) and 42 were private homes, summing up a total of 80 households. A total of 52 interviews were accomplished, 31 with private homes dwellers and 21 with collective residences dwellers. Dwellers of 38 different buildings (collective buildings and private homes) were interviewed. The two most frequent species found in the residential buildings analyzed were: Ficus pumila in 26 buildings (71%), Parthenocissus tricuspidata in 11 buildings (27%) and one building with both species (2%). The age of the green walls varied – as informed by the residents – between 2 and 32 years, with an average of 14 years. 4.1. The Symbols Evoked by Green Walls The interviewees were questioned about mental associations when thinking about green walls. The motivation of this question was to investigate which symbols were associated to this type of vegetation. The majority of residents – 92%, or 48 interviewees – associates green walls to positive aspects. Only 15% (8 dwellers) associates this vegetation to negative aspects (figure 3). 0%

10%

20%

30%

48%

Nature 27%

Psychological Positive Responses

Ancient Buildings Practical Aspects Undesirable Animals Humidity Others

50%

50%

Beauty

Benefits to Thermic Comfort

40%

12% 12% 10% 10% 8% 15%

Figure 3: Responses to the question “When you think about green walls, what do you relate to it?”

Beauty was the most common response, as 50% of the interviewees (26 respondents) related green walls to aesthetic improvements on the landscape and the building. Some researchers confirmed that there is a strong aesthetic preference for natural landscape sites compared to urban ones, especially when vegetation and water are present. The preference for urban environments that have natural elements also exists, when compared to similar urban environments without such elements [3, 19]. In the opinion of 48% of the interviewees (25 respondents), green wall is related to nature. This is

an obvious association, since the green wall effectively is a natural element on a building. Relations between this covering and less urban environments were also registered. Last but not least, 4 interviewees mentioned the benefits of green walls to the environment, pointing its capability to improve the air quality, the balance of wildlife, or simply saying that planting green walls is an ecofriendly practice. Another current association was between green wall and psychological positive responses, such as: peace, freedom, comfort, calm and well-being. These terms were cited by 14 dwellers (27%). It is noticeable that biophilia, i. e., the psychological positive effects due to the contact with green walls, is somehow perceived by dwellers. This is an evidence of the potential benefits to well-being of humans that can be provided by green walls. In addition to this fact, Ulrich [3] also mentions several researches in which results report that states of relaxation, peacefulness and other psychological well-being feelings are associated to exposure to landscapes with nature elements. It is also stated that reduced stress, mental fatigue and negative feelings (such as angry and fear) are verified in individuals in contact with natural landscapes [3, 20]. Increased thermal comfort inside the building were cited by 6 interviewees (12%). The fact that green walls have been applied for several centuries or that have traditionally been used in European countries was pointed by 6 respondents (12%). Its use in castles and ancient buildings were also mentioned. Five interviewees (10%) cited practical aspects of green wall, such as the protection of the masonry against graffiti, the possibility to mask imperfections of the mortar render or aesthetically unpleasant buildings and the lack of necessity of painting maintenance. Differently of the findings in other researches, a relation between humidity in the masonry and green walls was pointed only by 4 respondents (8%). On the other hand, other interviewees affirm that a reduction in the levels of humidity in the masonry covered by green walls is perceivable. Therefore, the influence of green walls on humidity of masonries is polemic, and requires further studies to clarify it. Another common matter during the interviews was the possible association between the green walls and the presence of undesirable animals inside the residence or on the wall. Only 10% of the respondents (5 interviewees) related green walls with undesirable animals, such as spiders and bugs. On the other hand, when they were questioned if they have ever visually verified any undesirable animal on the vegetation covering façades, those respondents affirmed that they have never seen any. They just explained that they believe that there is such relation. Additionally, a dweller informed that she use to keep the windows which are closer to the green wall closed in order to avoid the presence of undesirable animals inside her home. Ulrich [3] suggests that such extreme reaction could be evoked by seeing natural settings as a potential environment for the presence of snakes or spiders, even by non-phobic people. Despite the lack of evidence that could

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support their opinions, some interviewees believe that green walls are responsible for a higher incidence of undesirable animals in the residence and claim that this is their first thought about this type of vegetation. This can be seen as an evidence that, for some individuals, green walls incite biophobia. However, these feelings are not directly linked with the vegetation itself, but with the possible presence of threatening animals on it. Another worth mentioning evidence is that, for 44% of the interviewees (23 dwellers), a green wall easing the proliferation of undesirable animals is a myth. Ulrich [3, 19] addresses this issue, highlighting that humans could be biologically prepared to react to settings that might have hidden dangers or any other characteristic possibly related with threats by having moderate rejection or caution. Simply observing a fearful or strong aversive reaction of another person to a possible threat or being exposed to histories and myths of certain cultures about such dangers are sufficient to preempt aversive or defensive responses on human beings [3]. These statements clarify the reasons why, despite the lack of evidences, the myth of green walls being attractive to bugs and spiders can exert such feelings. Maybe, the persistent verbal repetition of the relation between green walls and undesirable animals had created a myth over the years that is now established in some kind of shared consciousness. It is also noteworthy that, in some cases, characteristics of the site per se can be the cause for the appearance of some bugs and small animals. It might be the case, for instance, of the proximity to a body of water or a forest and also previously known rodent infestation in local plumbing system and abandoned houses. While some people may ignore these evidences and think the green wall is responsible for the presence of undesirable animals, others understand that the whole environment may influence such presence. Therefore, the relation between green walls and undesirable animals was not confirmed by most dwellers. What is perceivable is that there is a rejection, by a small part of dwellers (only 10%), of green walls, due to the possible presence of undesirable animals, such as spiders and bugs. Indeed, there is no evidence that strong negative responses could be evoked by water or vegetation per se. A fearful or aversive reaction commonly occurs when the environment or the arrangement of natural settings are interpreted as a threat [3]. Accurate guidance about this non-occurrence can be effective in creating a stronger appreciation for the vegetation, because, according to some interviewees, there are people that reject green walls based on this myth only. 4.2. Advantagens pointed by dwellers Some positive characteristics about the use of green walls (both species) were pointed (figure 4) by the interviewees. Only 8%, or 4 dwellers, did not identify any advantage of its use. Aesthetic improvement to the buildings and, as a consequence, for the urban landscape was the most

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BUILDING PHYSIC (HYGROTHERMIC AND ACOUSTIC)

recurrent advantage, mentioned by 41 dwellers (79%). 21 respondents (40%) declared, as a positive aspect, the contributions of green walls to the integration between urban environment and nature. Psychological benefits were cited by 16 interviewees (31%). They describe these benefits as feelings of satisfaction, well-being and tranquility, as well as they believe that the presence of green walls creates a more comfortable and delightful environment. 0% 10% 20% 30% 40% 50% 60% 70% 80%

Aestethic Improvement

79%

Integration between Cities and Nature

40%

Psychological Positive Responses

31%

Maintenance

31%

Benefits to Thermic Comfort Redution of Humidity Others None

27% 12% 15% 8%

Figure 4: Advantages of using green walls, according to the interviewees.

For 31% (16 dwellers) maintenance of their residences is easier due to this covering. The remarkable characteristic, in this case, is the absence of the necessity of painting or doing repairs in the existent painting, because the vegetation hides imperfections on the masonry and protects it against acts of vandalism, such as graffiti. Benefits to thermal comfort, again, were related to green walls by 14 interviewees (27%). Among them, 7 affirmed that they perceive the thermal insulation provided by green walls and other 7 believe that temperature in summer is cooler in rooms whose outside is covered by this vegetation. Six dwellers (12% of respondents) declared that there is a reduction in the levels of humidity inside the house or in masonries due to the presence of a green wall on façades. 4.3. Disadvantages pointed by dwellers Henceforward, disadvantages of green walls are presented (for both species) according to the opinion of dwellers (figure 5). It is important to highlight that 9 interviewees (17%), were so satisfied that they did not identified any disadvantage of having green walls on their residences. Maintenance was the most remarkable disadvantage in the opinion of 37 respondents (71%). In some interviews, problems related to the development of the vegetation were cited, such as: disorder or intense development and need to restrict the area covered by vegetation. The necessary pruning of undesirable branches was the most recurrent complaint. In 12 interviews (23%) possible damages to the building caused by green walls were mentioned. Such damages could happen, according to them, on the painting, on the mortar render, on the masonry or on the structure. However, some authors disagree with such statements and many of those individuals were not able to properly identify the

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

problems on their own residence. For 21% (11 interviewees), undesirable animals are thought to be attracted by green walls and this fact is understood as a disadvantage of the covering. Presence of ants and mosquitoes was noticed on green walls. But this presence was considered of little disturbance and would not justify removing the vegetation. In case of Parthenocissus tricuspidata, there are evidences that, in summer, its flowers attract a certain species of bees. Besides, two events were reported about the presence of mice inside the residence. Despite the fact that the proliferation of mice is not related to green wall, its presence seems to have favored the access of such animals. This is why, in regions where there are rodents, the option for non-adoption of green walls take this into consideration. The increase in the levels of humidity due to green walls was mentioned by 7 respondents (13%) as a disadvantage of this vegetation. However, this statement contradicts reports of some authors and also statements made by others dwellers (for them, green wall acts as a protection against humidity, reducing the internal humidity). 0% 10% 20% 30% 40% 50% 60% 70% 80%

71%

Maintenance 23%

Damages to the Building

21%

Undesirable Animals Humidity Others None

13% 8% 17%

Figure 5: Disadvantages of using green walls, according to the interviewees.

4.4. Maintenance Regardless of the simplicity of the maintenance of green walls, it is important to reinforce that it must be regularly done and cannot be neglected. It was possible to identify that maintenance related to green walls could be divided into maintenance of the vegetation and maintenance of the masonry. The maintenance of the vegetation basically consists of pruning and removing the deciduous leaves in winter (in the case of the Parthenocissus tricuspidata). The interval between prunings for the species Ficus pumila, varied between 15 days and 6 months. On the other hand, for the species Parthenocissus tricuspidata, the interval between prunings varied between one pruning per month, in spring and summer (and no pruning in autumn and winter), and one pruning every two years. The bothersome due to the invasion of vegetation on the roof seemed to be the most common complaint. When developing on the roof, the branches of green walls can move shingles or block gutters, causing infiltration of water to the inside of the residence in periods of constant rain. Obstruction of gutters can also happen due to the concentration of deciduous leaves of the species Parthenocissus tricuspidata. Pruning green walls near doors and

windows is a necessity. Without such maintenance, damages might happen to the painting, as well as problems for the opening of doors and windows. We can conclude that Ficus pumila demands more maintenance, due to its constant and vigorous growing along the year. On the other hand, the species Parthenocissus tricuspidata demands less frequent pruning and, in winter, such care is unnecessary. Therefore, the use of Parthenocissus tricuspidata as green walls is the most advantageous in terms of maintenance.

5. CONCLUSION The results of this study confirmed that green walls can provide remarkable advantages and also have a great potential for the improvement of the urban environment. With regard to the symbolic meaning of green walls to dwellers, it is perceivable that, for the majority, this type of vegetation is associated to positive aspects. So, this supports the hypothesis that biophilia and green walls can be related. Contrary to popular myths, the relation between undesirable animals and green walls is infrequent among dwellers. Even so, such reports indicate that the biophobia related to animals, such as bugs and spiders, implies in rejection of green walls for some individuals, due to the supposition that this vegetation could work as shelter for such animals. For the interviewees, aesthetic improvement of façades; the integration between urban environment and nature and feelings of well-being are related to green walls. These testimonials, once more, reinforce the potential of green walls to improve the quality of life in the cities. We can also conclude that, in the view of dwellers, the disadvantages of this type of vegetation are mainly related to maintenance or controversial issues, for instance: damage on the masonries, presence of undesirable animals and increase in the levels of humidity. Regarding those possible problems, it is necessary to undertake further researches until these issues can be conclusive. After processing the analyses of the opinions in these interviews, it is possible to affirm that the most advantageous analyzed species of green walls is Parthenocissus tricuspidata. This is explained mainly by the demanding maintenance of the species Ficus pumila. For future studies we suggest the analysis of the environmental perception of dwellers of residences in which green walls had been removed, in order to compare to the results of this study. Moreover, researches focused in physical aspects of green walls (such as indoor temperature in summer and winter, humidity and damages on the masonries) will be of great significance.

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6. REFERENCES [1] PECK, S. et al. Greenbacks from Green Roofs: Forging a New Industry in Canadá. In: Research Highlight – Technical Series 01-101. Ottawa: Canada Mortgage and Housing Corporation, 2007. Retrieved oct, 10 from: http://www.cmhcschl.gc.ca/odpub/pdf/62665.pdf [2] SATTLER, M. A. Edificações Sustentáveis: Interface com a Natureza do Lugar. In: Menegat, Rualdo e Almeida, Gerson (org.). Desenvolvimento Sustentável e Gestão Ambiental nas Cidades: Estratégias a partir de Porto Alegre. Porto Alegre: Editora da UFRGS, 2004. [3] ULRICH, R. S. Biophilia, biophobia and natural landscapes. In S. R. Kellert & E. Wilson (ed). The biophilia hypothesis. Washington: Island Press / Shearwater Books, 1993. [4] DUNNETT, N.; KINGSBURY, N. Planting Green Roofs and Living Walls. Portland: Timber Press, 2004. [5] LORENZI, H. e SOUZA, H. M. Plantas ornamentais no Brasil: arbustivas, herbáceas e trepadeiras. 3 ed. Nova Odessa, SP: Instituto Plantarum, 2001. [6] GRAF, ALFRED BYRD. Tropica: color cyclopedia of exotic plants and trees: for warmregion-horticulture-in cool climate the summer garden or shelterd indoors. 4ª edição. East Rutherford: Roerhs, 1992. [7] CORREA, M. P. Dicionário de Plantas úteis do Brasil e das Exóticas Cultivadas. 6 vol. Rio de Janeiro: Ministério da Agricultura, 1926-1975. [8] GRAF, ALFRED BYRD. Exotica 3: pictorial cyclopedia of exotic plants: guide to care of plants indoors 9ª edição. New York: Roehrs, 1976. [9] KÖHLER, M. Green façades – a view back and some visions. In: Urban Ecosystems, vol. 11, nº 4, pg. 423-436. Springer Science + Business Media: 2008 [10] DESIGN FOR LONDON. Living Roofs and Walls – Technical report: Supporting London plan policy. London: Greater London Autority, 2008. Retrieved oct, 10 from: http://www.designforlondon.gov.uk/uploads/medi a/5_Living_Roofs_technical_report.pdf [11] SHARP, R. et al. Introduction to Green Walls – Technology, Benefits & Design. In: Green Roofs for Healthy Cities, 2008. Retrieved oct, 10 from: http://www.greenroofs.net/components/com_lms /flash/Green%20Walls%20Intro%20908b.pdf [12] GRUB, H. Ajardinamientos Urbanos. Trad.: José Luis Moro Carreño. Barcelona: Gustavo Gili, 1986. [13] JOHNSTON, J.; NEWTON, J. Building Green: a guide to using plants on roofs, walls and pavements. London: The London Ecology Unit, 1992.

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[14] MCPHERSON, G.; SIMPSON J.; LIVINGSTON, M. Effects of Threee Landscape Treatments on Residential Energy and Water Use in Tucson, Arizona. In: Energy and Buildings, nº 13. pg. 129-138. Netherlands: Elsevier Sequoia, 1989. [15] CANTUÁRIA, G. Microclimatic impact of vegetation on building surfaces. MA Dissertation – Environment and Energy Studies Programme. London: A.A. School of Architecture, 1995. [16] EUMORFOPOULOU, E. A. e KONTOLEON, K. J. Experimental approach to the contribution of plant-covered walls to the thermal behaviour of building envelopes. In: Building and Environment, nº 44, pgs. 1024-1038. Netherlands: Elsevier, 2009. [17] VALESAN, M. Percepção ambiental de moradores de edificações residenciais com Pele-Verde em Porto Alegre. MSc Dissertation. Programa de Pós-Graduação em Engenharia Civil da Universidade Federal do Rio Grande do Sul. Porto Alegre, 2009. [18] BARDIN, L. Análise de conteúdo. 3ª ed. Trans.: Luís Antero Reto e Augusto Pinheiro. Lisboa: Edições 70, 2004. [19] ULRICH, R. S. Aesthetic and Affective Response to Natural Environment. In: Altman, Irwin e Wohlwill, Joachim (ed). Behavior and the Natural Environment. New York: Plenum Press, 1983. [20] BERTO, R. Exposure to restorative environments helps restore attentional capacity. Journal of Environmental Psychology, n º25, pg. 249-259, 2005.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Energy Efficiency of a Pre-vegetated Modular Facade Prototype Maria Isabel TOUCEDA1, Francesca OLIVIERI1, Javier NEILA1 1

Department of Construction and Technology in Architecture, Technical University of Madrid, Madrid, Spain

ABSTRACT: The present paper focuses on the evaluation of the thermal performance of a pre-vegetated modular facade on draining cells implemented on an experimental mock-up installed in Seville, Spain. The frontage design was conceived as the external layer for a ventilated facade. The experimental procedure was based on the analysis of data obtained from the installation of this system on the mock-up in comparison with the other implemented solutions. With those data, a model could be made in order to simulate different solutions of facade for their comparison. Results indicated that the performance of this pre-vegetated facade was better than a solar protection system which minimized overheating. During summer, vegetation kept in shade the inner layers of the wall and leaves absorbed the incoming radiation, but also the evapotranspiration of the modules and plants was significant: It cooled the air chamber, decreasing the temperature in contact with the wall. Hence, energy consumption for cooling under summer conditions is considerably lower than with other facade solutions. Keywords: Thermal performance, Pre-vegetated facade, Ventilated facade, Experimental mock-up, Monitoring procedure

1. INTRODUCTION Green roof technology has been widely used in northern countries for a long time. Nowadays, in Germany, it is used in 14% of all flat roofs [1], but in Spain green roofs have only now become more common after their introduction and study in the 90’s [2]. However, green walls are much less studied and used. Over the past few years, the number of architectural interventions with vegetation introduced on the facades of buildings has been increasing [3], but mostly for reasons other than the envelope energy efficiency. Green roof thermal performance has been studied extensively. The current state of knowledge of the potential benefits of green roofs in relation to building energy consumption has been reviewed by Castleton et al. [4]. But in the case of green facades, more research is needed on their thermal performance. With more specific knowledge about thermal behaviour, green wall solutions could be taken into account within building legislation. Introducing vegetation on architecture has not only an effect on the thermal performance of buildings, but also on the environment. 1.1. Building thermal performance The vegetated solutions improve internal comfort and reduce energy consumption. -Reduction of heat flux and solar reflectivity: The vegetation provides protection against overheating and also provides some cooling through the evaporative process in the plants [5]. The solar radiation is balanced by sensible (convection) and latent (evaporative) heat flux from soil and plant surfaces. In summer the exposed area of a black roof can reach 80 ºC whereas the equivalent area beneath a green roof is only 27ºC [6]; A green roof can have an equivalent albedo of 0,7-0,85 [7], compared with the typical 0,1-0,2 of a bitumen/tar/gravel roof [8].

-Green roofs not only act to reduce heat loss in winter and heat gains in the building during the summer. They add thermal mass to help stabilize internal temperatures throughout the year [4]. 1.2. Impact on the environment Vegetation improves air quality, providing O2 and absorbing CO2. Calculations from Akbari have shown that the average sequestration rate for a 50m2 tree was estimated at about 11kg of CO2/year [9]. Also, soil and leaves absorb pollutants such as lead, cadmium or other heavy metals that would otherwise remain suspended in the air. The incorporation of vegetation in buildings contributes not only to better air quality, but also to reduce urban heat island effects in densely built areas [10] and enhance psychological well-being. Natural elements in urban spaces enrich the urban landscape and create micro-climates in streets and squares.

2. OBJECTIVES The objective of this research is to analyse a prototype of a pre-vegetated modular facade. The prototype has been installed on an experimental building at Seville, Spain. It has been realized in three steps: Design, construction and use phase. The objective at design phase was to describe the prototype: the general components of the system and the specific components for the experimental construction. The protocols and a plan to proceed were fixed for construction and measurement phases. The construction phase involved the manufacture of pre-vegetated panels, their development, transport and installation to the experimental building. The objectives of this phase were to verify the lightness and the ease of installation of the planted modules, to benchmark the results with existing commercial solutions, and to identify possible weak points in the

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process. For these objectives, each step of the process was described and timed. During the use phase, (the current one), the objective was to analyse the thermal performance of the facade constructed with vegetated panels, as well as to study the behaviour of chosen plant species and drip irrigation cycles. The thermal behaviour of different facade solutions can be analysed through data gathered by monitoring the experimental building.

3. DESCRIPTION 3.1. Description of the system The modules consist of polypropylene draining cell panels. The dimensions of the draining cell pieces are 480 x 260 x 52 mm, and they can be assembled in order to adapt the module to the support, being the only limitation the easy to manipulate the module. The cavities of the draining cells are filled with soil specifically mixed up for this case and climate: the proportion of turf, perlite and worm humus can vary. The ensemble is wrapped up with polyester felt. Several cuts are made into the felt in order to insert the plants. Plant species must be selected depending on the place: native species need low irrigation and maintenance. As opposed to what happens with hydroponics, with this system, vegetation grows up naturally on soil: bacteria and organisms adhered to the roots, they capture humidity and feed the plants with processed nutrients. When the roots fill the panels, their growth stops and no pruning is needed. Irrigation is a dripping system circuit. Spare water leaks into a water tank under the facade. This water will then be fed back into the circuit. The panels are used as the outermost layer of a ventilated facade. They can be placed directly on a vertical support or on a substructure fixed to the supporting element, and sustained by horizontal profiles, with a vertical removable bolt in order to allow an easy and quick installation of any of the modules and to prevent he panels from turn over (Fig. 1).

The modules are completely finished (assembled, wrapped and with vegetation) prior to the installation. Hence, the installation can be done faster. 3.2. Selected species The selection for the experimental building in Seville has taken into account the climate and the native vegetation. Seville has a Mediterranean climate. Summers are hot and dry and winters are mild. Koppen climate classification is Csa [11]. The annual average temperature is 18.6ºC (65ºF). January is the coolest month, with average maximum temperatures of 15,9ºC (61ºF) and minimum averages of 5,2ºC (41ºF). July is the warmest month with daily average highs of 35.3ºC (96ºF) Average minimum temperatures in July are 19,4ºC (67ºF) and every year the temperature exceeds 40ºC (104ºF) on several occasions. Rainfall varies from 600 to 800mm per year, concentrated in the period from October to April. The plant species have been selected taking into account the orientation of the facade where they are placed. On the South facade, where isolation is difficult in the summer, we have used native aromatics and sedum, such as Lantana sellowiana, Lampranthus, Drosanthemun hispidum, Rosmarinus officinalis postratus, Lotus maculatus, Plectranthus madagascariensis Plectranthus coleoides, Hebe buxifolia, Thymus vulgaris, Viburnum tinus On the North facade, where there is no direct radiation we have used Vinca pervinca, Hedera hélix (small leaf), Russelia equisetiformis, Plectranthus neochilus, Plectranthus ecklonii erma, Plectranthus madagascariensis, Grevillea lanigera Mt Thamboritha, mirtus communis 3.3. Description of the experimental building This facade has been installed in an experimental building in Las Cabezas de San Juan, Seville (Fig. 2). The mock up is an industrialised construction: 10m long x 3m wide x 3m high.

  Figure 1: Front and section of pre-vegetated facade. 01.Drainage cells; 02.Metallic frame; 03.Fix profiles; 04.Drip irrigation tube; 05 Removable bolts; 06.Enclosure wall

Between the wall and the vegetated layer, there is a ventilated air chamber. The air flow dissipates the humidity coming from the vegetated modules and takes heat from the back of the panels.

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  Figure 2: South facade and Plan of the Experimental building. Seville, Spain.

The building consists of five rooms: a kitchen on the West side, three test rooms (room 1, room 2 and room 3), and a bathroom on the East side. Every

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

room has a different facade solution. Facade panels P-08, P-09 & P-10 (facing north) are the same as the corresponding panels P-04, P-03 & P-02 (facing south) in order to have “slices” for qualitative measurements and comparisons among the indoor conditions in the three different rooms. Each of the facade panels has different U-values. The vegetated facade is installed on the North and South facades corresponding to room 3 (Fig. 2). The dimensions of the vegetated facade are the same both for North and South: 2186 mm long x 3720 mm high. The South facade has a 1197x1191 mm window in the middle.

(8) The internal partitions are formed by 2x15mm gypsum plaster-boards + 46mm of glass fiber + 2x15mm boards (Table 1). Table 1: U (transmittance coefficient) for the different layers of the envelope at Seville experimental building

Month

U (W/m2·K)

GRC panel

0.40

Thickness (mm) 80

Solar factor (%) Clear/dark 0.00

Floor

0.54

220

0.00

Partitions

0.53

106

0.00

Roof

0.00

195

Window

1.08

0.00 6/40

  4. MONITORING 4.1. Objective of monitoring

  Figure 3: South pre-vegetated facade of the Experimental Mock-up at Seville: Section, plans and image.

Composition of the Pre-vegetated facade from inside to outside (Fig. 3): (1) G.R.C. panel (Glass fibre reinforced concrete) with an innovative typology consisting of a GRC Sandwich with its smoother side facing indoors, overlapping the slab externally. (2) The metal frame is anchored to the main structure through cast-in channels in the sandwich, giving support to the external element of the facade. The frame is made of stainless steel, hollow rectangular profiles (cross-section 80x40 mm, thickness 2 mm); fixed profiles anchored to the metallic frame to hold the modules. (3) Vegetated modules; (4) The window (south facade) is an ElectroChromic Glazing Unit (SGR) with a low emissivity pane; (5) The prefabricated module is covered by a slab made of concrete poured over corrugated metallic sheets. (6) On the floor, the thermal insulation is achieved by the concrete slab (14cm) + expanded polystyrene foam (4cm) + projected mortar (3cm) + stoneware tiling. Over this slab it is installed an under-floor radiant heating system. For the design of the heating system, the chosen U min. has been that corresponding to the climatic zone of Madrid/Seville (the most restrictive one) described in the Spanish standard DB-HE 1[12] (Table 1). (7) Tank to save the spare water after the irrigation cycle before being fed back into the circuit.

After construction and assembling of the different elements, the monitoring systems were installed. Different sensors are placed at different layers of the green panels with this objective [13]. The obtained data are: outside dry-bulb temperature variation measured at the weather station; surface temperature variation at each layer of the enclosure; Interior temperature variation (air and superficial); relative humidity inside the air chamber; energy saving in the conditioning system. The floor radiant heating system in winter conditions and the air cooling in summer conditions (both independent for each room), keep the temperature inside each test room constant at 20ºC. With no flux exchange between the spaces (checked with a fluximeter), a comparison can be drawn between the thermal performance of different facade solutions by checking the energy consumption of the conditioning systems in the different rooms. 4.2. Equipment The measurement equipment comprises: A weather station located close to the building. It measures the following meteorological parameters every 15 minutes: outside air temperature, solar radiation, relative humidity, rainfall and wind speed. (Table 4) 14 surface temperature sensors (STS). The probe is in a flexible and adhesive silicone capsule. They are Pt-1000 (compatible with LON control and registration system) 1/3 DIN. This yields ΔT=±0,13°C at 20°C. 8 air temperature sensors (ATS). Pt-1000 is also used. 4 relative humidity transmitters with remote probe of 14x130mm with a range of 5-98%. Software for data registration. A clock-Calendar An energy counter for heat pump consumption. A fluximeter. The position of the probes is specified in Table 2 and Figure 4.

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Table 2:Probes and sensors at South (S) and North (N) facades; ST: Surface temperature Sensor, AT: Air Temperature Sensor; RH: Relative Humidity transmitter: FM: fluximeter; WS: Weather Station.

01, 02

S

Sensor Type ST

17,18

N

ST

03, 04

S

AT

19, 20

N

AT

05, 06

S

ST

24, 25

N

ST

07

S

ST

23

N

ST

08, 09

S

ST

15, 16

N

ST

10, 11

S

RH

21, 22

N

RH

12,13

S

AT

14, 26

N

AT

Num.

Facade

27

AT

28

FM

29

WS

Position External surface of vegetated modules In the shade, vegetated area External surface of the GRC panel

4.4. Measuring procedure Measurements are taken every five minutes and an average is calculated after three subsequent values. Energy consumption is registered once a day.

5. OBTAINED RESULTS OF MONITORING The data gathered after monitoring the experimental building show the differences in temperature on each layer of the facades. As an example, the graph shows a punctual measurement of the South facade under warm conditions (Fig. 5).

Internal surface of the GRC sandwich panel Internal surface of vegetated modules Inside the air chamber Inside the air chamber Hanged inside the local Internal partitions Outside the experimental building

On the South facade (Table 2), the external probes that can be affected by solar radiation are insulated. The probes are duplicated in order to assure that there is no period without data if any of the probes failed. The air temperature probe inside the test room checks if the temperature remains constant; The Fluximeter on the partitions between the different rooms checks that there is no energy flux between the rooms through the partitions; The weather station allows us to compare the data obtained in the test building with external data.

  Figure 5: Measurement of the temperatures at the different th South facade layers. November 12 2010, 13:47h.

We can see that the surface of the vegetated modules (polyester felt) reached, under no shade, 34ºC whereas the outside dry-bulb is 22,5ºC. The temperature inside the air chamber was about 4ºC lower, because of evaporative cooling and the convective air flow. Analysing other moments during the day, the decrease of temperatures inside the air chamber becomes more significant as the outside dry-bulb is higher. The graph (Fig. 6) shows the variation in temperatures during two warm days with the conditioning system off.

Figure 6: Measurements of South facade of the experimental building with conditioning system off. Seville, nd rd October 2 and October 3 2010

  Figure 4: Situation of air temperature sensors (AT), surface sensors (ST) and relative humidity transmitters (RH) at prevegetated facades.

4.3. Measuring period The measuring period started on September 2010 and will finish on July 2011.

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The first day there was an important temperature difference when the cloudy day became sunny and hot. For that first day, the graph shows an average of decrease about 7 degrees inside the air chamber during the hottest hours of the day, in relation to the outside dry-bulb temperature. During the second day, when the temperature is more constant, but lower than the day before, the graph shows a decrease between 3,7 and 7,9

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

degrees inside the air chamber during the hottest hours of the day. The variation of temperature inside the air chamber shows that the peak of temperature is completely absorbed. It also shows that the decrease of temperature inside the air chamber is more important as the outside dry-bulb is higher.

room temperature be about 3-4 degrees lower than with the shading facade without plants. The module with the vegetated facade keeps the air temperature under comfort ranges during the day with no air conditioning system needed. In another room without the ventilated façade, the average temperature of the day is 24 ºC.

6. SIMULATION Thanks to the monitoring data, a model of the experimental building could be developed in order to make a threefold comparison between the thermal performance of different case studies (Fig. 7): The facade composed just by the bare wall (case 1); The wall with a shading layer (case 2); And the wall with the vegetated modules (case 3).

  Figure 8: Simulation .Temperature variation with the 3 case study facades and no conditioning system on a typical summer day.

The second simulation was carried out with the cooling system on. It works from 7am to 11pm in order to keep the temperature inside the module constant on 20ºC (Fig. 9). On the graph (Fig. 9), we can conclude that the energy consumption for the building with the vegetated facade would suppose energy savings of 69% in relation to the solution with the bare wall for the day of the simulation, and 33% is the percentage of energy savings of the vegetated facade in relation to the ventilated facade without plants for the same day. Figure 7: Three cases for simulation: CASE 1.Bare wall; CASE 2.Wall with shading element; CASE 3.Wall with vegetal facade.

The model has been simulated with DesignBuilder software, which uses the EnergyPlus simulation engine [14]. Case 1: the climate data introduced for the simulation are taken from the meteorological station; In case 2, despite the limitations of simulating ventilated facades with this software, it can be deduced that the temperature inside the test room is mainly affected by the adjacent temperature (the temperature reached within the air gap) rather than by the outside dry bulb temperature; Case 3: In order to simulate the third case, the outside dry bulb temperature is replaced by the temperatures obtained inside the air gap after monitoring the experimental module. The first simulation was carried out with the conditioning systems off, and with no natural ventilation. The graph shows the air temperature evolution during a warm day (Fig. 8). It shows how the ranges of temperature variation are minimised and the peak values are absorbed. The average temperature of the day is 22ºC. The test room with the bare wall as facade reaches the higher temperatures. The wall with a shading element makes the room have a similar behaviour than with the bare wall, but the temperature is about 4 degrees lower. The wall with the vegetal facade makes the

  Figure 9: Simulation 2: Cooling energy consumption for the three case study facades on a typical summer day.

7. CONCLUSION Since the facade is conceived as a ventilated facade, the thermal properties of plants, such as insulation or absorption of leaves don’t have a direct effect on the building but on the environment. The ventilated facade is effective since it stops incoming solar radiation, keeping the wall in the shade. After the comparison between this vegetated facade system and any other ventilated facade, we will see that evaporative cooling behind the modules is the main factor explaining the drop in temperature inside the air chamber. The decrease in Seville reached 7 degrees in the hottest hours of the day.

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Using the monitoring data for the simulation, it yields energy savings around 33% in the cooling system in relation other ventilated facade solutions. With no conditioning system, the vegetated facade has an effect on stabilizing the temperature oscillation during the day. The air temperature is mostly under comfort conditions. We can conclude that the pre-vegetated modular facade system is an effective solution for hot and dry climates under summer conditions, where protection against insulation is advantageous and evaporative cooling has a higher potential. The vegetated facade is also an effective solution for the North facade in hot and dry climates. Even if there is almost no incoming radiation, the effect of evaporative cooling and the convective air flow causes a decrease of some degrees in the temperature in contact with the wall. 7.1. Future research The monitoring is still ongoing. Winter 2011, spring 2011 and summer 2011 periods are planned to be monitored. The conditioning systems will be working in order to keep the temperature inside the test room constant on 20ºC. The energy counter will gather the energy consumption for each test room with different constructive solutions. So we will know the annual energy savings in relation to the other facades. After the analysis and conclusions for this experimental mock-up, it would be hopeful to draw a comparison with the thermal performance under different climate conditions.

ACKNOWLEDGEMENTS The research has been funded by the research project INVISO (for the optimization of energy efficiency in housing, part-funded by the Spanish Science & Innovation Ministry, and ERDF) The experimental building has been constructed by DRAGADOS and SEIS, in the framework of I3CON project (a 4-year industry-led collaborative research project, part-funded by the EU). The authors also acknowledge technical contributions of Óscar Domínguez.

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8. REFERENCES [1] Herman, R 2003, ‘Green roofs in Germany: yesterday, today and tomorrow’, in: Greening Rooftops for sustainable Communities, Chicago, pp. 41-45. [2] Neila, F J, Bedoya C, Acha, C, Olivieri, F, & Barbero, M 2008, ‘Las cubiertas ecológicas de tercera generación: un nuevo material constructivo’, Informes de la construcción, vol. 6, pp. 15-22. [3] Lambertini, A 2007, Vertical: bringing the city to life, Thames and Hudson, London, UK. [4] Castleton, H F 2010, ‘Green roofs; building energy savings and the potential for retrofit’, Energy and Buildings, vol. 42, no. 10, pp. 1582-1591. [5] Del Barrio, E 1998, ‘Analysis of the green roofs cooling potential in buildings’, Energy and Buildings, vol. 27, no 2,.pp. 179-193. [6] FiBRE (Findings in Built and Rural Environments) 2007, ‘Can Greenery Make Commercial Buildings More Green?’ Cambridge University. [7] Gaffin 2005, ‘Energy balance modelling applied to a comparison of white and green roof cooling efficiency’, in: Greening Rooftops for Sustainable Communities, Washington, DC. 2005. [8] Reflective Roof Coatings 1993, Energy Efficiency Factsheet, Washington State University. [9] Akbari, H 2002, ‘Shade trees reduce building energy use and CO 2 emissions from power plants’, Environmental Pollution, vol. 116, pp. S119-S126. ‘ [10] Wong, N H 2009, ‘Energy simulation of vertical greenery systems’, Energy and Buildings, vol. 41, no. 12, pp. 1401-1408. [11] Guía resumida del clima en España: 19712000; 1961-1990, 2004, Dirección General del Instituto Nacional de Meteorología, Madrid. [12] Código Técnico de la Edificación: CTE 2009, España Ministerio de la Vivienda. [13] Wong, N H, Tan, A Y K, Chen, Y, Sekar, K, Tan, P Y, Chan D, Chiang, K, Wong, N C 2009, ‘Thermal evaluation of vertical greenery systems for building walls’, Building and Environment, vol. 45, no. 13, pp. 663-672. [14] http://www.designbuilder.co.uk/

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Passive strategies for roofing design in Costa Rica Shading, Form and Materiality Michael SMITH-MASIS Programa de Investigación en Diseño y Construcción Sostenible. Instituto de Investigaciones en Ingeniería de la Facultad de Ingeniería. Universidad de Costa Rica. San José, Costa Rica ABSTRACT: The roof in Costa Rica’s tropical climate has a critical role to provide shading and protection of heavy rains and solar radiation. It has a hierarchical role within the building’s envelope to prevent any indoor temperature raise above external air temperatures. This paper aims to define passive design strategies for the roof based on empirical and analytical studies. Form and materiality was analyzed with local low cost materials through a series of parametric simulations and analogical models. Keywords: Passive Design, Comfort, Shading, Roof form & Materiality

1. INTRODUCTION In Costa Rica the roof is commonly provided as a lightweight structure with a mono or double pitch. It is covered in the exterior with corrugated galvanized steel sheeting and gypsum or plywood board as ceiling. Even though of its decisive role on the overall building thermal performance, it is typically found in local practice (mainly due cost) a lack of ceiling boards, poor insulation or any reflective foils to minimize heat gains, and if a ceiling due exists, trapped air inside unventilated cavities find no escape for any heat surplus. Therefore heat is conducted through the underside of the roofing sheets and re-radiated to the interior spaces producing thermal stress and occupants discomfort, the latter has a double effect when occupants are wearing light clothing (Szokolay, 2004), especially in low cost buildings. Locally speaking it is of common believe that this issue can be easily solved by applying international standards usually associated with recognized commercial materials. However on the local practice there are clearly misconceptions with poor design decisions based on air-conditioned buildings, and expensive materials that can be avoided with simple design techniques, informed upon appropriate criteria. The aim of this paper is to generate a series of practical exercises to evaluate form and materiality of roofing systems for Costa Rica. The research focuses on testing local materials and low cost alternatives through a series of parametric simulations and laboratory tested models to validate the exercises with further explorations upon shading, form and materiality.

2. THE ROOF HIERARCHICAL ROLE “In the tropics, it is the shade that refreshes and unifies, […] and it is everywhere. In the tropical latitude the local experience of family cohesion becomes relative and dilutes through the open

spaces – some members of the family lie on a hammock under the shade of a tree, others in the corridor seated on a bench under the shade of the eaves.” (Bruno Stagno,1999). The quote above describes from a socio-cultural perspective how outdoors experience is part of the ‘way of living’ in Costa Rica, and open spaces under shade are traditionally conceived for family spatial delight; where shading becomes a key-performing feature in which the roof has a hierarchical role. The roof in Costa Rica’s is primarily required to provide shading and protection of heavy rains and solar radiation. It is the element that yearly receives the highest amounts of solar radiation. Since openness in the building is required in such climates, the roof has a hierarchical role among other elements, which practically remains it as the only considerable element that protects interior spaces or any external surfaces from solar irradiation impinge. Well designed, a roof can prevent any indoor temperature raise above external air temperatures, by keeping surface temperatures under the roof (ceiling) around the same level as other surfaces in the interior space.

3. COSTA RICA’S CLIMATES & DESIGN Costa Rica is a tropical country located between latitudes 8º and 11º north and longitudes 82º and 86º west. It is a relatively small country nevertheless with a great diversity of ecosystems and climates. Annual temperatures are not very accentuated; with only two season variations throughout the year (dry and rainy). However climate differences exist due dominant winds and variety of altitudes up to 3.820 meters above the sea level. There are more than 50 known microclimates in Costa Rica. For building design purposes, based on temperatures, relative humidity, rainfall and general design recommendations, four main regions are distinguished among others; cool (moderate,) warm, warm-dry and Warm-humid.

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5. ROOF MORPHOLOGY The outside, middle and inside sections of a roofing system contribute to prevent heat transmission. All together determine layers of thermal resistance with its correspondent U-value (Figure 2).

Figure 2: Roof Morphology & Layers.  

Figure 1: Sun-path Diagram, Solar radiation Stress & Typical Warm Regions Temperatures.

In all climatic design regions, the roof has decisive protective role, especially to keep indoor air temperature comfortable. In this latitude, solar radiation has a strong impact over all exposed surfaces, and unwanted radiant heat can be conducted inside the dwelling through the buildings elements, especially during sunshine hours close to the zenith, were solar radiation reaches its peak loads (Figure 1). The same sun path diagram can be used due the country’s small size.

4. A THERMAL COMFORT TARGET Research from various writers has proven that the ASHRAE summer recommendation of 26.1ºC is not applicable for tropical climates. In fact, in developing countries due the limited available resources, constructions are simple and operate without any conventional cooling i.e. air conditioning. People are more likely to tolerate higher temperatures, hence to adapt to external ambient conditions. Nonetheless, predominant corrugated galvanized roofs under severe exposure can create intolerable indoor conditions; with external surface temperatures 30ºK higher than the air temperature. A rule of thumb suggested by Koenigsberger & Lynn (1974) for these type of climates, establishes that the ceiling temperature should not exceed air temperature by more than 4 ºK to keep comfortable conditions. Despite the fact of a “relative elderly” benchmark, the recommended standard has practical implications for low cost materials that can be easily provided.

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The outside layer or “roofing sheet” contributes to reflect solar radiation, depending on surface finishes. A white or shiny silver surface is preferable because of its highest reflection, lowest absorption and emission of radiant heat. Givoni (1998) suggests assuming an absorbance value of 0.6, unless the building is periodically painted because it is impractical to assume a perfect white colour (0.9) in warm humid climates, due abundant fungi growth or even corrosion over roof and walls. The middle layer separates the roofing sheet from the ceiling, containing an attic space or air cavity and linings of a reflective foil. In warm climates the roof surface is warmer than the interior surface of the ceiling, thus an air gap can help to reduce heat gains by convection. Also, air spaces are good insulators, however at higher temperatures, external surfaces and airspaces conductance increases and resistances become smaller. To prevent any heat excess in the cavity, ventilation might be necessary when the external air temperature is below internal air temperatures. Heat gains can be furthered reduced by adding a radiant barrier (reflective foil) in the cavity; it reflects most of the long wave radiation but if it absorbs any heat, very little will be reradiated to the colder surfaces in the cavity. According to Givoni (1995), lining one surface of the air gap with a reflective lining increases its thermal resistance by two to threefold and placing the lining on the upper horizontal part of the air cavity reduces the possibility of dust accumulation, which can greatly lower its power to reflect or low emit. The Inside layer is composed of insulation materials and ceiling boards. Additional thermal resistance comes along with materiality to prevent ceiling’s interior surface temperature rise above the performance standard, depending on surfaces emittance.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

6. THERMAL RESISTANCE RECOMMEND U-VALUE

AND

In spite of the performance standard (4ºK) and taking into account the sol-air temperature concept, a temperature radiation gain can be estimated in the roof surface, along with its correspondent thermal resistance. Givoni (1998) suggest a procedure to calculate the required thermal resistance, with approximating assumptions as a function of external colour, shading conditions and acceptable elevation of indoor radiant temperature (Figure 3). The sol-air temperature elevation can be estimated by the equation: dTs-a = (a.I/Ho)-4ûK (Where: Ho: heat transfer coefficient, a: absortivity and I: Solar Radiation) The required thermal resistance for mediumcolour roof: R =(R * dTs-a) / 4¼K- R) The assumptions for this calculation considered 0.6 of absorbance, external surface coefficient (Ho) of 2 15 w/m ºC with very light winds, internal surface 2 resistance (R) of 0.14m *ºC/w, where Ti = To and 2 solar radiation is 896 w/m . After Givoni’s procedure and by using the 1 correspondent climatic data the external roof surface temperature elevates 35.8 ºK above the external air temperature. After subtracting the recommended performance standard (4 ºK) the final temperature radiation gain is 31.8 ºK, with its 2 required thermal resistance of 0.96 m ºC/W. Knowing the required resistance, individual values are assessed for each layer of the roofing system.

Figure 3: Required Thermal Resistance.  

Figure 4: Layers of resistance & U-Value  

 

Figure 4 shows that the most significant resistance comes from the air cavity and insulation materials, however the latter can be expensive. Also by comparing the obtained U-value with similar roofing systems, a range from 1 to 1.5 W/m2ºC can be deduced for this purpose; expecting ceiling temperature to be 2.5 to 3.5 ºK. above external air temperature.

7. FORM CONSIDERATIONS In Costa Rica, roofs are typically provided as double-pitched slopes (15% to 20% gradient), with short overhangs (0.50m), where economical issues restrict orientation and any sloping criteria. Thus careful attention has to be paid towards surface tilt (slope degree), orientation and eaves extension to obtain the best possible performance. Figure 5 shows how solar radiation approaching an exposed surface can be reduced as function of the tilted plane (Weather files of Metenorm V.6); such criteria has been well understood by local vernacular architecture with prevailing 35% roof slopes. On the other hand, local regulations establish overhangs with a minimum extension of 0.50m, where only high altitude angles can be covered and certain critical periods (Figure 6.A,B,C) are unshaded. Also south and north facades should encourage longer eaves, without diminishing daylight availability; and considering protection from diffuse radiation coming from the whole sky hemisphere. Balconies or shaded verandas are preferable for this asset, however careful attention has to be paid in terms of cost and daylight availability. Figure 6: 1,2,3 presents shading studies where VSA can cover almost all critical periods. For example a VSA of 53º, can provide sufficient shading to a 2,40m wall height. A fully year coverage can be enhanced by adding HSA. On the other hand east and west facades are difficult to shade. In this case VSA of 45º can cover periods from 8:00 to 16:00 hours. The addition of horizontal elements underneath the overhang i.e. louvers, or vegetation can enhance shading provision.

 

1

Day 141 peak radiation at 13 hrs of 896 w/m2. Source: Meteonorm V.6.

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A parasol roof concept was tested under the same assumptions with different distances between the roof and a highly reflective lightweight fabric (0.9) as second skin. The roofing sheet was kept alone (uvale 5.8) with the second skin (u-value 4.6). Then the roof was improved as on the previous studies (0.9). Figure 7.B illustrates that such element mitigates the temperature raise of the ceiling interior surface until 5 ºK above the external air temperature. The temperature difference between offset distances of 0.15 to 1m is 1.3ºK, with a threshold after 0.25m. It can be observed that short distances have a greater chance to provide shading with similar effects to a fully ventilated air gap situation, and with less material consumption. Ultimately a roof u-value of 0.9 drops the ceiling’s temperature below the acceptable standard.

Figure 5: Effects of solar radiation as a function of a tilted plane.

Furthermore shading the roof can reduce both; solar radiation loads and cost for any expensive insulation. This can be easily achieved by means of adjacent trees, trunks or wide natural canopies. However if natural means are absent, a ‘Parasol roof’ (Szokolay, 2004) can be used over the roof itself to provide shade. Figure 6.G illustrate a lightweight textile-shading element that can be set on top of a roof. Such element can provide enough shading and allow convective cooling underneath. At night it can be folded if radiative cooling is required. Lightweight roofs can cool down very fast, specially during night hours, when its temperature is often below the ambient air temperature, owing to long-wave radiation to the sky (Givoni,1998).

8. DIGITAL TEST

EVALUATION: PARAMETRIC

A series of parametric simulations with TAS 9.0 (dynamic thermal simulation software) were performed to determine the individual contribution of each layer and materials. To ensure the comparability of results, all other factors (wall construction, window type and openings) were kept the same for a 27 cubic meters generic box. The internal surface of the ceiling was measured to distinguish the differences by adding each layer and materials. The external and ceiling temperatures were taken at the same day (121) Figure 7.A. The results show that starting from the roof sheet alone, the greater impacts were perceived by adding the ceiling board and air gap. Insulation showed less improvement over the peak hours, and attain temperatures higher than any other roof tested. Lower U-values tend to dissipate heat at slower rate; keeping ceiling’s temperature higher at night. In opposition higher U-values dissipate heat immediately to the environment. However it cannot be denied that finding the right insulation material will benefit the overall thermal performance targeted.

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Figure 6: Shading studies & Parasol Roof Concept.

Despite the fact of the software sensibility and materials calibration, the resulting computational values were approximates which help to illustrate what was approached with the ‘manual calculations’. Even though there are some minor discrepancies between simulations results and manual calculations, the performance contribution of each layer can be visualized in a practical way.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

November ensuring perpendicular solar radiation during peak hours (due equinox proximity). Environmental measures were taken from a local weather station and infrared surface thermometers. Sets of 4 boxes were displayed daily to compare performance, each set of 4 boxes was arranged under 6 categories varying: % ventilated air cavity, slope degree, air gap width, thermal insulation, external colour and a parasol textile. Exercises 1,2 and 3 pursued form studies, revealing slightly differences, upon a range not greater than 2ºK. The external ceiling surface temperature performed closely to the external air temperature. Exercises 4,5,6 explored materiality variations. As expected, temperature differences were evident between performance curves (Figure 8) and 4ºK standard. Test 4 (insulation) registered more temperatures outside the required standard, whilst test 6 showed a significant shading impact from the parasol roof. The later can be easily achieved with low cost fabrics for plants shading (“zaran”) or by means of reused publicity tends.

10. CONCLUSIONS CONSIDERATIONS

Figure 7: Roof performance simulations  

9. ANALOGICAL TESTING: MODELS All theoretical exercises studied digitally were validated and tested under a series of 1:1 scale models. The main objective was to explore low cost local materials and a parasol roof. A set of plywood 2 boxes of 0.60 m where built to explore form and materiality. DBT, RH, solar radiation and ceiling interior surface temperature were measured. The latter and external DBT were the main performance indicators. Measurements were taken under real exterior conditions from September to early

&

DESIGN

Roof design is contextual-dependant (location), and should consider occupant’s needs and materials optimization. Its main goal is to reduce the envelope exposure against adverse climatic conditions. Eaves extension or overhangs should be encouraged as much as possible to ensure shading, without diminishing daylight availability. Pitch angles on a range of 15º to 30º or higher can reduce the effects of solar radiation impinge. A double pitch roof oriented north to south will benefit from less exposure. To prevent any ceiling’s temperature increase above the recommended standard of 4ºK, it should be considered reflective external surfaces (Light colours), ventilated air cavities and resistive insulation if necessary. A U-Value of 1.5 is recommended for this asset. Whenever the roof has no access contextual shading (e.g. trees or natural canopies) a parasol roof should be consider; reducing heat loads from solar radiation. Previous analysis recommended an offset distance of 0.25m, for a lightweight textile element. Finally analogical studies reveal the importance to explore alternative low cost materials, while typical applications can be furthered measured on local case studies. Further qualitative research upon the 4ûK standard may be encouraged to validate its feasibility.

11. ACKNOWLEDGEMENTS I will like to acknowledge UCR-INII director Mrs. Ofelia for her support along the process. Also Ernesto Viquez and Javier Castro for their assistance and contribution to develop field studies, environmental measurements and model fabrication.

 

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Figure 8: Roof types test Models and performance

12. REFERENCES [1] Auliciems, A. & S. Szokolay (1997) PLEA Notes: Design Tools and Techniques 3 Thermal Comfort. PLEA, Brisbane. [2] Corbella, O.D. and Magalhães, M.A. (2002). Reflections about Bioclimatic Architecture in the Tropics, pp693-696, PLEA 2002, Touluse. [3] Givoni, B. (1998) Climate Considerations in Building and Urban Design. John Wiley & Sons, Inc., New York [4] Givoni, B. (1994) Passive and Low Energy Cooling of Buildings. Van Nostrand Reinhold. [5] Hyde, R.(2000). Climate Responsive Design. E & FN Son, London.

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[6] Koenigsberger, O., T. Ingersoll, A Mayhew and S. Szokolay (1973) Manual of Tropical Housing and Building, Part 1: Climatic Design. Longman Group Ltd., London. [7] Koenigsberger, O. & R. Lynn (1965) Roofs in the Warm Humid Tropics. Architectural Association, London. [8] Stagno,B. Ugarte, J.(1998). Rural Architecture in the Tropics. Institute of Tropical Architecture, San Jose. [9] Szokolay, S.(2004) Introduction to Architectural Science: the basis of sustainable design. Architectural Press, London.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBN xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011 th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The Application of Passive Downdraught Evaporative Cooling in Hot and Dry Climate of China Huang XUAN 1 and Brian FORD 2 1

Department of Architecture, School of Naval Architecture, Ocean and Civil Engineering Shanghai Jiao Tong University, 800 Dongchuan RD. Minhang District, Shanghai, 200240, China 2 Department of Architecture and Built Environment The University of Nottingham, University Park, Nottingham, NG7 2RD UK ABSTRACT: This paper describes the work on investigating the application of Passive Downdraught Evaporative Cooling (PDEC) in hot and dry climate in China and the integration of different passive design strategies with PDEC system in this climate. To test the systems performance in practice, made possible by the very similar climate characteristics of the two locations, a full scale prototype field monitoring experiment was carried out in collaboration between Nottingham University and AICIA, in Seville, Spain. The performance analysis showed that the system can achieve significant cooling in Hot and dry climate conditions. Problems emerging during the field work related to disturbances in air flow and the lack of integration of other passive environmental strategies with PDEC were tested by PHDC - Airflow and TAS simulation. The optimal design found was tested in the climate conditions of Kashi, results proving that the PDEC system can be a viable alternative to air conditioning in hot and dry climates of China. The environmental strategy for a new commercial building in Kashi, China was assessed with bioclimatic analysis. A natural ventilation and passive cooling strategy was developed taking in consideration of the results of the previous testing and analysis. Keywords: Passive Evaporative Downdraught Cooling, Climatic applicability, Hot and Dry climate, China

  1. INTRODUCTION The majority of projects adopting Passive Downdraught Evaporative Cooling (PDEC) are located in hot and dry climate conditions, where the use of PDEC is the most appropriate, and together with other passive strategies it can provide almost 100% of the cooling requirement in summer [1]. Despite a significant percentage of the climate in China falls in this category, at present there is no example of the use of PDEC. This paper investigates the potential of using PDEC in the hot and dry climate of Xinjiang, China through an experimental prototype in Seville, South Spain characterized by similar climate conditions. It describes a theoretical design project of a new commercial building in Kashi, southern Xinjiang, China, showing that the PDEC system can be applied in the hot and dry climate of China and can achieve good cooling performance.

2. CLIMATE OF XINJIANG AND SEVILLE China is a large country with varied climate. To assess the downdraught cooling climatic applicability in China maps were developed for the first time as part of the thesis research on The Application of Downdraught Cooling in China. [2] A new approach was proposed for the maps, which were developed based on three related climatic characteristics: CDH (Cooling Degree Hours), TDBT-TWBT (Dry Bulb Temperature – Wet Bulb Temperature) and 26℃TWBT (26℃ – Wet Bulb Temperature). The two indexes, TDBT-TWBT and 26℃ - TWBT, indicate the potential of evaporative cooling and the possibility of using evaporative cooling to reduce the cooling

demand. Seven climate zones for downdraught cooling were classified. Three climate zones (Dry, Moderate Humid and High Humid) were identified by TWBT depression, which were divided into two subzones with the difference of cooling degree hours (hot and warm). Based on the map it was identified that almost 100 km2 of floor space of non-domestic buildings (non residential) is located in the Hot and Dry climate and thus suitable for PDEC. [2] Adopting PDEC in non-domestic buildings in this climate locations in China has a great energy and CO2 saving potential. The market analysis of China showed that almost 100km2 non-domestic building can achieve 500 million RMB and more that 50000 tonnes of CO2 savings per year when PDEC is applied. [2] Xinjiang is located in the northwest of China, and stands in the centre of Eurasia, far from both the Pacific and the Atlantic Oceans, leading to an arid and rainless, typical type of inland dry climate. The climate of Kashi is a temperate continental arid climate. It is a typical south city in Xinjiang province with hot and dry climate. The highest monthly average high temperature is 32.1 °C in July. In summer(Jun.-Aug.), daily maxima dry bulb temperature is above 35°C, RH minima is below 30% and Wet bulb temperature generally is lower than 21°C, providing ideal conditions for the application of evaporative cooling. Furthermore in the difference of temperature change between day and night is large, meaning the possible use of night ventilation. Kashi is located in the Hot and Dry zone. (Figure 1) The TDBT-TWBT and 26 °C – TWBT value is 7.7 and 9.3 respectively. [2] This indicates the use of PDEC

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systems to cool the air is applicable in Kashi. The significant cooling potential of PDEC can yield improvements in thermal comfort, and significant reductions in energy demands compared with equivalent air-conditioned buildings. [3]

Figure 2: Location of Seville in the PDEC applicability map of Spain Temperature. Map showing the difference between outdoor Dry Bulb Temperature vs. outdoor Wet Bulb Temperature. Average over 24hours for June – September.

 

Figure 3: Location of Seville in the PDEC applicability map of Spain Temperature. Map of China showing the difference between indoor Dry Bulb Temperature (taken as 25°C) vs. outdoor Wet Bulb Temperature. Average over 24hours for June – September.

3. FULL SCALE FIELD MONITORING OF THE EXPERIMENTAL BUILDING IN SEVILLE Figure 1: Location of Kashi in the Downdraught Cooling Applicability Map of China a) Map of China showing the difference between outdoor Dry Bulb Temperature vs. outdoor Wet Bulb Temperature. (b) Map of China showing the difference between indoor Dry Bulb Temperature (taken as 26°C) vs. outdoor Wet Bulb Temperature. June – August.

The climate of Seville is a typically Mediterranean climate throughout the year, with cool winters and sunny, hot and dry summers. The highest monthly average high temperature is 36 °C in July & August. Seville’s climate in the summer is very similar to that of Kashi. The TDBT-TWBT value is in the range of 7.29.4 and 25 °C –TWBT is between 5.5-7.8. (Figure 2 and 3) [4] As the summer climate of the two locations is highly similar the results of full scale field monitoring there, can provide good indications about the application of PDEC in hot and dry regions of China and can be applied in Kashi as well.

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3.1. Background To look at the PDEC system operation in real climate conditions, a full scale prototype experiment was carried out in collaboration between Nottingham University and AICIA, in Seville, Spain. [5] The experiment took place in the cell installed in the School of Engineers of the University of Seville during the months of August and September 2009. One of the main aims was to see the effectiveness of PDEC from the temperature difference achieved between the outside temperatures and the inside ones. The experimental plan was based on measures of temperature inside the cell under various conditions: with or without cooling system and various configurations of this. To measure the inside temperature 9 sensors were used. Furthermore, during the field work spot measurements to record or surface and air temperature, air velocity and RH were done. The experimental cell consisted of a prefabricated house with a tower attached to the system installed with micronisers. (Figure 4) 

 

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011 th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Temperature without system obtained by correlation (Ti (corr)) was 42°C, meaning a 10°C reduction by the PDEC cooling effect. (Figure 6)

Figure 4: Photo of the prototype building and Prototype Airflow strategy

3.2. Cooling System The system comprised of 8 nozzles at 1pair/bay in four sets provided. The water volume flow required for each nozzle is approximately 1litres/hour. Nozzles operate with a total volume of 8 L/h of water, with 4 possible settings. The wind catchers (north side of top tower, 2m×0.5m) are subjected to considerable wind condition (opening with no wind), the vent is operated by five steel louver, rotated by pinions located on a tubular drive shaft operated by motors. The tower high level inlet vent is fully open with 2m×0.3m which located at top of south side. The cell had 4 fans on a door, two extracting fans 400 m3/h Φ0.2 and the other two fans 600 m3/h Φ0.25, with 2 setting, 1000 m3/h and 2000 m3/h9. When the air extraction fan are switch on, the inside warm air exhausts via these fans, or when the fans are switched off, inside warm air exhausts via these fan vents by natural convection. 3.3. Cooling performance During the testing period the system could achieve significant cooling even in the hottest days. With natural ventilation (8 microniser, no fan) the system could achieve a 7 °C reduction in the internal temperature (Ti(medida)) compared to the External temperatures (Te). (Figure 5)

 

Figure 6: Internal temperatures on the 7th of September (8 micronisers, 4 fans)

These results are promising and show the potential of the PDEC system for cooling in Hot and dry climate conditions. However the measurements and observations also revealed more features which could be improved such as insufficient air flow, disturbance in air flow patterns in natural ventilation, high humidity and stuffiness of the air, furthermore still too high temperatures for comfortable conditions. When looking at the results it needs to be taken in consideration that no other environmental strategies, such as shading, high thermal mass, night ventilation were incorporated in the experimental building, as it was solely build for testing purposes and not to represent comfortable living conditions. To address these problems air flow and TAS simulations were carried out. First the cooling load and the required air flow with the original conditions was estimated and problems related to air flow were investigated by using the PHDC Air Flow software, created by AICIA [6]. After the findings it was concluded that the cooling load is too high for the PDEC system and by using TAS simulation different environmental strategies were incorporated in the design and an optimal design was suggested. (Table 1) The optimal design included the addition of an exhaust tower to increase air flow and thermal mass, night ventilation and solar shading to reduce the cooling load were added. The optimized example prototype was tested in the climate conditions of Seville (day 202 in the Seville Spanish Weather for Energy Calculations weather file) [7] and also Kashi (specifically for day 215 in the Kashi CTYW weather file) [8].

Figure 5: Internal and external temperature on 28th August, (8 microniser, no fan)

While when the system used forced convection (8 micronisers, 4 fans) the maximum Internal Temperature is 32°C and Temperature at tower low level outlet (Tsaltorre(med)) 24°C while the

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 1: Added environmental strategies for optimal design

Environmental strategy

Details

Exhaust Tower

Height : 2.4m, Exhaust stack height: 2.7m, Width: 1m, Cross section: 2.6m2, Free section of Exhaust: 1.5m2

Thermal mass

Cell wall and ceiling: 200mm concrete (density of 1800 kg/m³) with 100mm rock wool insulation (U-value: 0.34W/m2°C) Tower: 6mm steel with 100mm rock wool insulation and covered with low emissivity membrane (Uvalue:0.37W/m2°C)

Night ventilation

Open with low night-time temperatures

Solar shading

Adding to the south, west and east facade

temperature reduces significantly and follows that of outside as a result of night ventilation.

 

 

The analysis below shows the results for the TAS simulation specifically for day 202 in the Seville SWEC weather file. This is chosen as a reference day for all comparisons as the warmest hour of the day occurs on this day and reaches 41°C. After adding the proposed environmental strategies (thermal mass, insulation, night ventilation and solar shading the external heat gain was reduced to 365W. This together with increased air flow by the exhaust tower (1104.5 m3/h) resulted in the office hours’ peak internal temperature reducing to 27.1°C at its peak. (Figure 7) A very good result considering the high external temperature 41°C used as a reference.

Figure 8: Cell T, External DBT, External WBT in Kashi

 

Findings and experiences of the field work and simulation were considered when developing the environmental, natural ventilation and passive cooling strategy for a new commercial building in Kashi below.

4. XINJIANG DESIGN CASE STUDY The project of the Tuman River Resort, in Kashi, Xinjiang was a unique initiative in China, the only one using PDEC system. Although due to financial reasons the project was postponed, it has significantly contributed to the knowledge of application of PDEC cooling system in hot and dry climate of China, as performance and emerging problems already can be investigated in the design process. 4.1. Local Context The project of the Tuman River Resort located at the south of Kashi city centre and close to Tuman 2 River. The Resort has a total of 116309 m building areas, which includes retail-hotel buildings, theatre, administration commercial and reception centre. The experimental building for passive cooling is one of the retail-hotel buildings of 1577 m2. The building incorporates a three-storey atrium surrounded by perimeter cellular rooms. The rooms on the first and second floor are hotel rooms and ground floor is a retail area.

Figure 7: Cell T, External DBT, External WBT in Seville

Testing results in Kashi proved that the PDEC system can be a viable alternative to air conditioning also in the hot and dry climate regions of China. When outside temperatures reached 36.7°C the cell temperature is below 27°C its trend is fairly stable, without bigger swings as a result of high thermal mass. (Figure 8) During the night hours the

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Figure 9: Perspective of Tuman River Resort proposed retail building

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011 th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The starting point for Kashi Tuman River Resort Experimental Building is a new commercial building in Xinjiang, China, which was designed by Xinjiang architectural design institute. The author and some other partners provided design proposes and developed a natural ventilation and PDEC cooling strategy for the Tuman River Resort Experimental Building in Kashi, Xinjiang. 4.2. Environmental Design Strategy The project aimed to explore the application of PDEC in a new building scheme in urban sites of China. The objective was to develop a natural ventilation and passive cooling strategy able to provide comfort conditions throughout the year to the occupants of the experimental building. To assess the environmental strategy Building bioclimatic charts (BBCCs) were used, as they provide an approach of rapid testing whether or not PDEC is likely to produce comfortable conditions in buildings [9]. The hourly temperatures for the period of June to August for Kashi were plotted on the Givoni BBCC (Figure 10). To assess PDEC, the hourly values for June to August are plotted along with the direct evaporative cooling boundary (27%). Integrated with other passive strategies, such as natural ventilation (17%), high thermal mass with night ventilation (31%), sun shading (42%) thermal comfort can be achieved all the summer time.

warmth and coolness by night ventilation, the thermal mass will dampen the temperature swing as well. The building has different environmental strategies for different seasons. The environmental design strategy proposed a PDEC Tower to provide cooling in the summer. The implementation of PDEC within the central 14 metre high atrium provides cooling air by using micronisers. In summer passive evaporative cooling and ventilation is provided by a PDEC atrium. The air is cooled at high level by mean of water misting nozzles supplied by Ingeniatrics S.L. and delivered by openings in the corridor to the occupancy spaces. The air will be then exhausted via the perimeter shaft. The perimeter stacks are designed to exhaust air at both high and low level, depending on the existence (or absence) of wind. (Figure 11) The PDEC system relies on 3 lines each one of 20 nebulizers, with a predicted water consumption of 20 l/h and a pressure of 2 bars in the line of nebulizers. The average size of droplets is 15-30 microns. The PDEC system is controlled by a control panel, it start, stop and purge in automatic operations by temperature and RH sensors. The PDEC system also operates in conjunction with the motorized dampers. When the system is on, both the motorized dampers at top of the atrium and high level vents at corridor are set to fully open or 50% open, according to the wind speed/direction.

 

Figure 11: Kashi experimental building summer PDEC Strategy Figure 10: Bioclimatic Chart for Kashi (after Givoni)

This analysis suggests that PDEC can be effective at maintaining thermal comfort and become a viable alternative to air conditioning in buildings located in hot and dry climates, but other applicable passive strategies need to be used at the same time. Taking this in consideration alternative environmental strategies were incorporated in the design proposal to minimize the solar gain and reduce the cooling demand. The building has a 200mm concrete wall with 100mm external insulation. The solar shading and low-E double glazing in the south façade reduces the heat gain significantly. The concrete walls are exposed, to absorb and store

 

When the external temperature drops well below the ‘neutral’ temperature, which occurs frequently at summer night, useful convective cooling is promoted. This is achieved by encouraging flow reversal in both still and windy conditions. The air comes in from the perimeter windows and exhausts through the atrium at high level by buoyancy forces reversing the daytime air movement pattern under downdraught cooling (Figure 12). The night cooling is controlled via the motorised dampers. Night-time convective cooling coupled with the mass of the building is also part of the design strategy to enhance the performance of PDEC.

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

5. REFERENCES

Figure 12: Kashi Experimental building summer night cooling and mid-season ventilation strategy (right).

During the Mid-season (spring and autumn) the building is naturally ventilated (by stack or wind pressure differences) until the outside air temperature is several degrees above internal. The use of natural ventilation for cooling the building will depend on the external temperature. When the outdoor temperature are below internal temperatures, indoor cooling can be achieved by natural ventilation. 4.3. Conclusion The results from the full scale field monitoring and TAS and Air flow simulation in Seville and Kashi showed that the system can be applied in the hot and dry climate of China and can achieve good cooling performance. The findings and observations from this project can give a good picture about the potential of the application of PDEC in hot and dry climates of China. The theoretical design project of a new commercial building in Kashi, southern Xinjiang, China considered the observations and results of the previous testing. The results of the bioclimatic analysis in line with the previous findings showed that other environmental strategies are necessary for the PDEC system to function well and to maximize its cooling performance. To ensure the system is working the first principle should be to try to reduce external heat gain furthermore the cooling load of the building. The right distribution air flow inside the building (without fan) is extremely important. This can decide if the system is able to work or not. The building needs to be designed to achieve the required air movement. Furthermore the location of the cooling tower should be carefully considered to avoid solar heat gain and by considering prevailing wind directions. 4.4. Acknowledgements I would like to recognise the efforts of Professor Servando Alvarez and Professor José Salmerón, AICIA, University of Seville, Spain, for providing technical guidance of the field monitoring of the experimental building in Seville.

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[1] FORD, B., (2001). Passive downdraught evaporative cooling: principles and practice. Environmental Design. Architectural Research Quarterly, 5, pp.271-280, Cambridge University Press [2] Xuan, H., (2010), The Application of Downdraught Cooling in China, PhD Thesis University of Nottingham, England [3] FORD, B. and HEWITT, M.G. (1996), Passive down-draught evaporative cooling in nondomestic buildings: A review of the current state of the art. Proc PLEA'96, Berlin [4] ALTENER II, 2003. Solar Passive heating and Cooling. Market Assessment of the Potential Application of Passive Downdraught Evaporative Cooling in Southern Europe 2001-20034.1030/c/00-009/2000, Applicability Mapping, Part of final report, ALTENER II Project on Solar Passive Heating and Cooling, European Commission – DG Research. [5] Alvarez S., Salmeron JM., Sanchez J., Ford B., Gillot M., ‘Analysis of a PHDC (Passive and Hybrid Downdraft Cooling) experimental facility in Seville and applicability to the Madrid climate’. Submitted to Energy and Buildings. In review. [6] Ford.B, Schiano-Phan.R, & Francis.E. ‘The Architecture & Engineering of Downdraught Cooling: a Design Sourcebook’ ISBN 978-09565790-0-3. PHDC Press, UK. 2010 [7] Spanish Weather for Energy Calculations (SWEC). Available at : http://www.eere.energy.gov/buildings/energyplus/ cfm/Weather_data.cfm [Accessed: 07.03.2011] [8] Zhang Qingyuan and Joe Huang. 2004. Chinese Typical Year Weather Data for Architectural Use (in Chinese). ISBN 7-111-14810-X. Beijing: China Machine Press. [9] LOMAS, K.J. et al. (2004). Building bioclimatic charts for non-domestic buildings and passive downdraught evaporative cooling. Building and Environment 39, pp.661 – 676

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Evaluation of passive cooling in low energy police office HILDE BREESCH1, BRAM DE MEESTER2, RALF KLEIN1, ALEXIS VERSELE1 1

Catholic University College Ghent, Department of Industrial Engineering, Sustainable Building, Ghent, Belgium 2 Arcadis Belgium NV, Ghent, Belgium

ABSTRACT: Natural night ventilation is driven by wind and stack generated pressures and cools down the exposed building structure at night, in which the heat of the previous day is accumulated. This passive cooling technique is applied in the low energy police office Schoten (Belgium). Thermal summer comfort in the offices is analysed based on the adaptive temperature limits indicator. Design, operation and performance of natural night ventilation are also evaluated. The design is compared to design guidelines for natural night ventilation. The operation is evaluated by comparing measured opening/closing of the windows to the designed control system. The performance is analysed based on the achieved temperature drop overnight. Measured data of indoor temperatures and opening/closing of windows were collected from the building management system during short periods in the summers of 2009 and 2010. Good thermal summer comfort is noticed during normal and warm summer periods. Only when the maximum outdoor temperature exceeds 30°C, high indoor temperatures are measured. Too low temperatures in the morning are noticed in some landscaped offices in normal summer periods. This can be solved by raising the set point for indoor temperature. The users have a large impact on the achieved thermal comfort by manual opening and closing of the windows by day. A rather good agreement is found between measured and designed operation of natural ventilation. Daytime activation requirements have to be checked. The temperature drop overnight varies between 0.3°C and 2.9°C. Keywords: low energy building, passive cooling, natural night ventilation, thermal comfort

1. INTRODUCTION Natural night ventilation uses the outside air at night as a heat sink to cool down a building [1]. The air enters the building and cools down the exposed building structure, in which the heat of the previous day is accumulated. This airflow is driven by natural ventilation forces as thermal buoyancy (stack effect) and wind. The cooling mechanism of natural night ventilation is based on the convective heat transfer from the exposed building structure to the cold air flow at night, i.e. when the cooling potential of the cold outdoor air temperature is maximal. By day, the thermal mass of the building structure is used to accumulate solar and internal heat gains and prevent uncomfortable conditions during building operation hours. This has three important consequences. Firstly, to make natural night ventilation work, heat storage in the internal structure is necessary [2], [3]. The phase difference between heat transfer to and from the building structure has to be bridged. Secondly, natural night ventilation is most effective in cool and moderate climates with a large diurnal temperature difference over the summer [4]. Thirdly, since this technology provides primarily sensible cooling, natural night ventilation is less applicable in warm humid climates. The humidity ratio of the outside air should be less than 15 g/kg dry air [4]. Natural night ventilation is applied to cool several office buildings in Belgium, e.g. Renson in Waregem [4], SD Worx in Kortrijk [5] and PROBE in Limelette [6], office building of the Law Courts in Antwerp [7]. In addition, Pfafferott et al. [8], [9] studied the performances of natural night ventilation in Germany in the laboratory and office building of Fraunhofer

ISE (Freiburg) and office building of DB Netz AG (Hamm). Voss et al. [10] monitored the energy consumption in 21 office buildings in Germany with night ventilation. Finn et al. [11] examined the role of design and operational parameters in a naturally night ventilated library in Ireland. Thermal comfort was examined by monitoring the indoor temperature and the relative humidity in these buildings. These examples demonstrate that the requirements of good thermal comfort can be fulfilled in a moderate climate in case of a low cooling load. Natural ventilation by day and night is designed to guarantee a good thermal comfort and indoor air quality in the low energy police office in Schoten (Belgium). This paper aims to evaluate the design, operation and performance of natural night ventilation. Moreover, thermal summer comfort in the offices is analysed. Measured data of indoor temperatures and opening/closing of ventilation openings were collected from the building management system during short periods in the summers of 2009 and 2010. This evaluation is based on the results of Cnudde and Swankaert [12].

2. LOW ENERGY POLICE OFFICE 2.1. Building description Figure 1 shows the low energy police office in Schoten (Belgium). This office building has been in use since September 2008 and is a design of Huiswerk architecten (architect) and Arcadis (engineering office HVAC systems and structural engineering). The building includes individual and landscaped offices, meeting rooms, storage rooms, cells, sanitary and changing rooms on two floors with a net floor area of 2514 m² (see also Figure 2).

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As only the offices are naturally ventilated, this analysis is limited to the offices.

Figure 1 Low energy police office Schoten (Belgium)

The building has a global insulation level K24 and an energy performance level E55, significantly lower than the required level for new office buildings in Flanders: K45 and E100 [13][13]. In 2009, an electricity consumption of 82.8 kWh/m².a and a natural gas consumption of 76.1 kWh/m² were measured. The U-values of the walls are discussed in Table 1. All walls are constructed of thermal capacitive materials (e.g. concrete brickwork in façade, hollow core concrete slab in floor) and the internal surfaces are unfinished so that heat can be stored in the internal structure.

velocity, but can also manually opened or closed by the user. The installed power of the lighting is on average 7.2 W/m² in the offices. The lighting in the offices is occupancy controlled. Most offices are occupied from Monday till Friday from 7h30 till 17h30. Some landscaped offices are also used in the weekends. Table 2 gives an overview of the total internal heat gains in each office during occupancy. In the offices, a large variation is noticed, between 14 W/m² in the individual offices and 26 W/m² in the landscaped office vk2. The maximum internal heat gains in the lunch and meeting room are higher, approximately 36 W/m². Table 2 characteristics of windows, ventilation openings and internal heat gains room

Awindow/ Afloor (%)

Internal heat gains (W/m²)

Aopening/ Afloor (%)

Office corps head

29

14

1.7

Office adjunct corps head

29

14

1.7

Landscaped office ggpz

14

20

1.4

14

14

0.8

11

17

0.9

28

17

1.1

Façade

U (W/m².K) 0.28-0.44

Landscaped office bp Landscaped office intervention Landscaped office cb Landscaped office vk1

30

20

1.0

Table 1:U-values of walls

wall Roof

0.18

Landscaped office vk2

28

26

0.7

Floor on slab

0.31

Lunch room

30

37

1.1

Window

1.92

Meeting room

23

35

1.6

2.2. Passive cooling

Figure 2 plan of first floor of police office (n°6 meeting room, n°7 landscaped office ggpz, n°8 office corps head, n°9 adjunct corps head, n°10 landscaped office cb)

The area of the windows, in relation to the floor area, for each room is shown in Table 2. This percentage varies from 11% to 30%. The solar heat gain coefficient g of the windows is 0.60. The windows in the atria have a g-value of 0.33. Figure 1 shows a large overhang on the west side of the building. Moving blinds are provided as external solar shading devices on the east and the south façade. The solar blinds are automatically controlled based on the measured illuminance on the façade and wind

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Natural ventilation by day and night is designed to guarantee a good thermal comfort and indoor air quality. The air enters the building in the offices through automatically controlled bottom hung windows and leaves the building at the top of 4 atria in the centre of the building (see Figure 3). These atria are marked in grey on Figure 2. The area of the exhaust openings is 14.7 m². The area of the supply ventilation openings, in relation to the floor area, is shown in Table 2. This percentage varies between 0.7 and 1.7%. The height difference between supply and exhaust openings measures 2m and 5m on respectively the first and ground floor. The openings are designed to deliver an airflow of 5 ac/h, considering a temperature difference of 7°C. These supply openings are automatically controlled, as shown in Table 3. The exhaust openings in an atrium are opened when the supply openings in at least one ventilation zone are opened and the indoor temperature in the atrium exceeded 24°C by day. The same bottom hung windows are used for hygienic ventilation and maximally opened for 25% by day. This day ventilation is controlled by occupancy in the individual offices and by CO2concentration in the landscaped offices i.e. opening when the concentration is higher than 900ppm and

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 3 principle of natural night ventilation in police office Table 3: Activation requirements natural night ventilation

Daytime activation requirement θi,max > 24°C θe,mean > 12°C

Night ventilation activation requirements 22h < time < 6h θi > 21°C θi - θe > 1°C v < 10 m/s no rain θi : indoor temperature (°C) θe : exterior temperature (°C) v: wind velocity (m/s)

3. EVALUATION PASSIVE COOLING On the one hand thermal summer comfort in the offices and on the other hand the design, operation and performance of natural night ventilation are evaluated. Measured data of indoor temperatures and opening/closing of windows were collected from the building management system during short periods in August 2009 and July 2010. An overview of the meteorological data of these periods is shown in Figure 4. Both periods had extremely high average and maximum temperatures. July 2010 and August 2009 had 15 respectively 14 summery days, i.e. maximum temperature exceeding 25°C, significantly higher than normal (6 days). Sunshine duration was normal in August 2009 and abnormally high, i.e. an occurrence of once every 6 years, in July 2010.

Te,ref =

(T

today

25

+ 0.8Tyesterday + 0.4Tday beforeyesterday + 0.2T2 daysbeforeyesterday 2.4

32 30 28

(1)

Tmax 65% acceptability Tmax 80% acceptability Tmax 90% acceptability Tmin 90% acceptability Tmin 80% acceptability Tmin 65% acceptability

24 22 20 8

10

12

T

14

e,ref

20

)

26

18 6

30

16

(°C)

18

20

22

24

Figure 5 Limits of the adaptive temperature limits indicator for an alpha building [14]

15

3.2. Design, operation and performance natural night ventilation

10 5 0

This criterion, developed in the Netherlands, is based on the adaptive thermal comfort theory [15]. The adaptive temperature limits indicator distinguishes two types of buildings. The type alpha and beta buildings differ in the availability of operable windows and the possibility to adjust the indoor temperature and clothing. The police office building in Schoten is caracterised as a type alpha building. Thermal comfort is divided into three levels, Level A corresponds to 90% thermal acceptability and is applied in buildings with high performance requirements to thermal comfort. Level B (80% thermal acceptability) means good indoor thermal comfort and is the standard level. Level C (65% thermal acceptability) finally, is only applied in temporary situations in existing buildings. Figure 5 shows the adaptive temperature limits for an alpha building. The minimum and maximum limiting indoor operative temperatures on a given day depend on the effective outdoor temperature Te,ref, i.e. the running mean external temperature of that and the three preceding days (Eq. 1). The effective outdoor temperatures of 3, 9, 16 and 22°C correspond to winter, autumn/spring, summer and hot summer situations in The Netherlands respectively. Comparison of the climatological normals for Uccle [17] and De Bilt (1971-2000) [18] shows that the Dutch weather is comparable to the Belgian.

Ti,o (°C)

closing when it is lower than 600ppm. In addition, the users can manually open and close these windows.

average Tmean (°C)

average Tmax (°C)

average Tmin (°C) 13.1

normal

17.1

21.6

jul/10

20.5

25.8

15.6

aug/09

19.4

24.9

13.8

Figure 4 meteorological data of July 2010 and August 2009 in Uccle (Belgium)

3.1. Thermal summer comfort The adaptive temperature limits indicator (ATL) [14] is chosen as the criterion to evaluate the long term performance of the police office building with natural night ventilation in respect of thermal comfort.

The design of natural night ventilation in the police office in Schoten is evaluated by comparing it to design guidelines for natural night ventilation of Breesch and Janssens [19]. Firstly, good thermal comfort is only possible when the internal and solar heat gains are restricted. The internal heat gains are recommended not excessing 20 to 30 W/m² floor area. In addition, the window area is recommended to be limited to 20% of the conditioned floor area. External sunblinds have to be provided with a solar heat gain coefficient g (glass included) smaller than 0.2. Secondly, to make natural night ventilation work, heat storage in exposed heavy ceiling or walls is necessary. This means that a lowered ceiling is

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31 30 29 28 27

Ti [°C]

discouraged. Moreover, it is recommended to construct the façade or one or more internal walls in heavy materials. Thirdly, cooling with natural night ventilation requires large airflows and thus large ventilation openings, i.e. an effective opening area of 1 to 3% of the cooled floor area. Finally, automatically controlling of the ventilation openings is recommended to maximize the cooling capacity and to overcome overcooling in the morning. The most important set point is the minimum zone or ceiling temperature. Night ventilation should also only be permitted when the zone temperature exceeds the external temperature. To evaluate the operation of natural ventilation, measured opening and closing of the bottom hung windows is compared to the designed control system in Table 3. The performance of natural night ventilation is analysed based on the achieved temperature drop overnight (between 10 p.m. and 6 a.m. the next day).

25 24 23 22 21 20 17

18

19

min 2010

20

21 22 23 24 Te,ref [°C] max 2010 min 2009

25

26

27

max 2009

Figure 7 evaluation thermal summer comfort (ATL) in office corps head

4. RESULTS AND DISCUSSION

Ti [°C]

4.1. Thermal summer comfort Thermal summer comfort is evaluated in an individual office, i.e. the office of the corps head (n°8 on Figure 2) and two landscaped offices, i.e. ggpz (n°7) and bp (same location as ggpz but on the ground floor). Figure 6 shows the indoor temperature in the office corps head in a warm week in July 2010. nd On July 2 , no registration of temperatures was noticed from 13h till 20h. The indoor temperature varied between 22.2 and 29.1 °C.

26

31 30 29 28 27 26 25 24 23 22 21 20 17

18

19

20

21

22

23

24

Te,ref [°C] max 2010 min 2009

min 2010

25

26

27

max 2009

Ti [°C]

Figure 8 evaluation thermal summer comfort (ATL) in landscaped office bp

Figure 6 indoor temperature in office corps head

To evaluate the indoor temperatures in this office, the adaptive temperature limits indicator is applied in Figure 7. Minimum and maximum temperatures in July 2010 and August 2009 are compared to the limits of thermal acceptability levels. In normal and warm summer periods, thermal comfort in the office of the corps head had a thermal acceptability of 80%, i.e. level B. However, in hot summer periods, thermal acceptability was only 65% or level C. This conclusion corresponds to the observations in the Renson office building [4].

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Figure 8 and Figure 9 show the evaluation of thermal summer comfort with the adaptive temperature limits indicator in the landscaped offices bp and ggpz respectivelyFigure 7. It can be noticed that indoor temperatures in office ggpz were on average 2°C higher than in office bp. Lower internal heat gains in the latter office (see Table 2) explains this difference. Moreover, too low temperatures in the morning were noticed in the office bp in normal summer. Due to this, thermal acceptability was less than 65% in this

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

office with regard to the lower temperature limit. This problem can be solved by raising the night ventilation control set point. 4.2. Design natural night ventilation Firstly, Table 2 shows that the internal heat gains in the offices in the police office are lower than 30 W/m² as advised in the guidelines. The window area does not meet the recommendation but is restricted to 30% of the floor area (see Table 2). External sunblinds are provided in the police office. Secondly, heat storage in internal structure is possible because all walls are constructed in thermal capacitive materials and the internal surfaces are unfinished. Thirdly, the area of the ventilation openings varies between 0.7 and 1.7% in Table 2, barely exceeding the minimum guideline of 1%. Finally, the automatic control system in Table 3 meets the guidelines for controlling night ventilation. In conclusion, the designed natural night ventilation system in the police office in Schoten in general meets the recommendations for natural night ventilation.

Figure 10 operation night ventilation in office corps head

4.3. Operation and performance natural night ventilation

Figure 11 operation night ventilation in landscaped office bp 3.0 2.5

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The operation of natural night ventilation in the office corps head is shown on Figure 10. The daytime activation requirements were fulfilled every day in this short period in July 2010. Consequently, natural night ventilation has operated every night in this summer period. On July 1-2 and 7-8, night ventilation started later than 22h because the indooroutdoor temperature difference was lower than 1°C. Regularly opening and closing of the ventilation openings was noticed on July 2-3, probably caused by wind and/or rain. In the nights of July 4-5 and 5-6, a low temperature drop overnight was noticed although a large indoor-outdoor temperature existed. Figure 11 discusses the operation in the landscaped office ggpz. The operation in the landscaped office bp is similar. Natural night ventilation has only operated during short periods although the activation requirements were fulfilled. The maximum daytime indoor temperature exceeded 24°C during the whole summer period. This set point has to be checked to guarantee a good thermal summer comfort. Consistent with the operation in the individual office, delayed start was noticed on July 12 and 7-8 and regularly opening and closing on July 2-3 in the landscaped offices. The performance of natural night ventilation in the office corps head and landscaped offices bp and ggpz is shown on Figure 12. The temperature drop overnight in the individual office varied between 0.7 and 2.9°C with an average of 1.6°C. In the landscaped offices, the temperature drop overnight was slightly lower with an average of 1.0°C and a variation between 0.3°C and 2.2°C. The temperature drop in the police office building Schoten was significantly smaller than the average temperature drop of 3 to 4°C in the Renson office building [4].

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4.4. User impact The users have a large impact on thermal comfort by manually opening and closing the ventilation supply openings and the windows by day. The latter was not registered in the building management system. This is demonstrated on Figure

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13 showing the operation of hygienic ventilation in the office corps head. A large increase of indoor temperature on August 20 was noticed in this office when the user manually opened the bottom hung window for natural ventilation on a hot summer day. In addition, Figure 6 shows a temperature drop in the morning of July 5 in office corps head, probably caused by manually window opening.

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5. CONCLUSION A good thermal summer comfort is noticed during normal and warm summer periods. Only when the maximum outdoor temperature exceeds 30°C, high indoor temperatures are measured. Too low temperatures in the morning are noticed in some landscaped offices in normal summer periods. This can be solved by raising the set point for indoor temperature. The users have a large impact on the achieved thermal comfort by manual opening and closing the windows by day. A rather good agreement is found between measured and designed operation of natural ventilation. Daytime activation requirement with regard to the maximum indoor temperature has to be checked. The temperature drop overnight varies between 0.3°C and 2.9°C.

6. REFERENCES [1] M. Santamouris, D. Asimakopoulos (Eds.) Passive cooling of buildings, James & James, London, United Kingdom (1996) [2] B. Givoni, Passive and low energy cooling of buildings, Van Nostrand Reinhold, New York, USA (1994) [3] C. Balaras, Heat attenuation, in: Santamouris, M. and Asimakopoulos, D. (Eds.), Passive cooling in buildings, James & James, London, United Kingdom, (1996) 185-219. [4] M. Kolokotroni, Night ventilation in commercial buildings. Annex 28: Low Energy Cooling, Subtask 1. IEA. United Kingdom (1995) 7-11

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[5] H. Breesch, K. Descheemaeker, A. Janssens, L. Willems, Evaluation of natural ventilation systems in a landscaped office, proc. 21st PLEA Conference, Eindhoven, The Netherlands (2004) 157-162 [6] H. Breesch, A. Bossaer, A. Janssens, Passive cooling in a low-energy building, Solar Energy 79 (6) (2005) 682-696 [7] N. Heijmans, P. Wouters, Pilot study report: Probe, Limelette, Belgium, In: Heiselberg, P. (Ed.), Principles of Hybrid Ventilation, Hybrid Ventilation Centre, Aalborg University,Aalborg, Denmark, http://hybvent.civil.auc.dk (2002) [8] W. Reyntiens, Monitoring of thermal summer comfort of the new Antwerp Law Courts, Ghent, Belgium, Ghent University, M.Sc, (2008) [9] J. Pfafferott, S. Herkel, M. Jäschke, Design of passive cooling by night ventilation: evaluation of a parametric model and building simulation with measurements. Energy And Buildings 35 (2003) 1129-1143 [10] J. Pfafferott, S. Herkel, M. Wambsganss, Design, monitoring and evaluation of a low energy office building with passive cooling by night ventilation. Energy And Buildings 36(5) (2004) 455-465 [11] K. Voss, S. Herkel, J. Pfafferott, G. Löhnert, A. Wagner, Energy efficient office buildings with passive cooling – Results and experiences from a research and demonstration programme, Solar Energy 81 (3) (2007) 424-434 [12] D.P. Finn, D. Connolly, P. Kenny, Sensitivity analysis of a maritime located night ventilated library building. Solar Energy 81(6) (2007) 697710 [13] W. Cnudde, S. Swankaert, Evaluation of passive cooling in police office Schoten (in Dutch), M.Sc, Catholic University College Ghent (2010) [14] http://www.energiesparen.be/epb/overzichteisen (in Dutch) [15] A.C. van der Linden, A.C. Boerstra, A.K. Raue, S.R. Kurvers, R. de Dear, Adaptive temperature limits: a new guideline in The Netherlands A new approach for the assesment of building performance with respect to thermal indoor climate. Energy and Buildings 38 (1) (2006) 8-17 [16] R.J. de Dear, G.S. Brager, Thermal comfort in naturally ventilated buildings: revisions to ASHRAE Standard 55. Energy and Buildings 34 (6) (2002) 549-561 [17] http://www.kmi.be/meteo/view/nl/360955Maandelijkse+normalen.html#ppt_4285694 [18] http://www.knmi.nl/klimatologie/normalen19712000/per_station/stn260/4normalen/260_debilt.pdf [19] H. Breesch, A. Janssens, Natural night ventilation in office buildings built in passive house standard, proc. Passive House, Brussels, (2007) 271-278

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Sustainability and Heritage Conservation Assessment of Environmental Performance and Thermal comfort conditions of historic churches. MAGDALINI MAKRODIMITRI1, JAMES W. P. CAMPBELL2 1 2

Department of Architecture, University of Cambridge, Cambridge, UK Department of Architecture, University of Cambridge, Cambridge, UK

ABSTRACT: Large hall structures are particularly common in historic buildings. The way large halls have been designed with very high ceilings, massive un-insulated masonry walls and cold stone floors, provides particularly difficult environmental challenges. This paper consists part of a doctoral research currently being undertaken in Cambridge, which focuses on a common type of hall structure-the church. The scope of the research is to study the problems involved and provide guidance to allow managers and curators of historic buildings to understand the consequences of the various decisions they take in devising suitable modern heating systems and strategies. This paper presents the survey data of two pilot studies. The analysis of results is oriented to the evaluation of current environmental conditions of the two representative cases in terms of thermal comfort provision and risk of historic elements deterioration. The pilot study involved a sustained monitoring of the internal environmental conditions coupled with carefully-designed questionnaires used to determine perceived levels of comfort. This paper highlights the problems of sustainable thermal comfort provision in large hall structures in historic buildings that host collections of artworks and proposes a route forward for finding acceptable methods of heating such buildings without causing long-term damage. Keywords: conservation, thermal comfort, churches, heating

1. INTRODUCTION Reducing energy consumption from buildings reduces bills, releasing funds to be spent in other areas and helps to reduce the volume of harmful greenhouse gases being released into the atmosphere. A growing range of issues are involved in managing properties. Churches are large structures, which are of value to local communities and are often significant tourist attractions, yet they are usually under-utilised. Historic buildings could be put to alternative uses, but in order to attract more activities, they need to provide a more comfortable environment. However it is important that any increase in thermal comfort level does not compromise conservation requirements and the need to reduce energy consumption and carbon emissions. This study focuses on historic churches in the UK, because:  They are quite complex structures  Their large hall spaces present particular difficulties when it comes to space heating and managing humidity levels, air movements and heat currents.  They are infrequently occupied  They are often listed buildings; therefore any environmental adaptation needs to have no adverse effect on the appearance and behaviour of the structural materials and artworks. The Stern Review Report (2006) concluded that Climate Change is an urgent problem that requires immediate action. [1] The Church Buildings Council accepted this, stating in The Church of England’s

Seven–Year Plan: “Shrinking the footprint”, published in October 2009, that it aims to achieve a 80% reduction in Churches’ carbon emissions by 2050. [2] Figures presented by “The Carbon Trust project 2008” reveal that most energy usage in church buildings is attributed to heating, [3] However modern heating systems are usually associated with particular conservation problems. A wellheated church is largely a Victorian invention and a late twentieth-century expectation [4], while modern society’s demand for increased thermal comfort conditions cannot be ignored. The problem is how to improve thermal comfort conditions in historic buildings, while reducing energy consumption and making sure all conservation requirements are still met. This paper examines the problem from thermal comfort perspective and presents and evaluation of comfort levels in two representative types of heated churches.

2. BACKGROUND 2.1. The challenge of historic churches adaptation Reducing energy consumption of church buildings is a significant challenge. More than 2/3 of churches (16,000 in total) are listed buildings (that is buildings protected under UK legislation and recognised as being of great historic importance). This means that conservation of historic fabric needs to be carefully considered. [2] Thus, passive measures, i.e. ceiling or wall insulation, windows draught-proofing etc. are often impractical.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. The Church of England consists of 16,200 churches, 43 cathedrals, around 100 offices, roughly 13,000 clergy homes and other buildings. The figures released in the Carbon Trust project in 2008 estimated that during 2006 – 2007, these building emitted over 330,000 tCO2 [3] (Fig. 1), of which a staggering 65% of emissions (approximately 212,000 tonnes) could be attributed to churches and halls. [2]

etc.); Heat tends to rise to the upper levels of the internal space, while the intermittent operation of heating causes high intensity heating-cooling cycles. (Fig. 2) [8]

Figure 2: a).Temperature (T) and relative humidity (RH) profiles sampled 4.5 m above the altar of a church with intermittent heating in Italy. Source: Camuffo, 2007

2.3. Conservation vs Thermal comfort Figure 1: Carbon Dioxide Emissions from Church of England estimated by source. Source: CofE, 2008

43% of churches were found to use natural gas for space heating and 21% used oil. [2] In all cases it was found that space-heating is the most significant factor in terms of carbon dioxide emissions. [5] 2.2. Heating strategies in historic churches Heating methods until now were chiefly designed to serve economic and thermal comfort requirements, while conservation issues have been very rarely considered. [6] There are two heating strategies often used in English Churches:  Constant operation of Central Heating system: the whole church volume is heated and, it is expected that uniform thermal conditions will be achieved throughout. The most popular types of central heating nowadays are warm-air heating, convective and fan-assisted heating, under-floor heating, and footboard heating. [6] In the case of central constant heating, higher indoor temperatures are generally expected to provide higher levels of thermal comfort. [Camuffo 2007] However, when a constant heating strategy is adopted in cold regions, Relative Humidity (RH%) might fall below the threshold of tolerability for wood and other organic materials (30% - 60%). [7]  Intermittent operation of central or localised heating: Local heating cuts the energy bills, since heating is targeted at the occupied areas of the church. Usually, IR heating from high-temperature emitters and pew heating are used. [6] The local method is less common than central heating, and although it usually fails to provide thermally comfortable conditions for the occupants, it causes particular conservation problems. Intermittent or mixed operation of heating often causes damage to the upper parts of the structure (e.g. ceiling, upper parts of walls, wall paintings

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The historic structures and artworks that are often found in church buildings are invaluable. The problems arise from rising demands for increased levels of thermal comfort and most importantly requirements for higher. [6] Modern heating techniques have changed perceived levels of thermal comfort. However, changes to the internal environment always affect the historic fabric and artworks which are at risk from a number of different types of deterioration: a). rising damp which is caused either by dispersed or ground water [9] b). Mould growth due to high humidity levels in the interior, mainly because of rapid changes in microclimate conditions c). Condensation on cold wall surfaces, due to changing thermal conditions, the increase of indoor air’s moisture content and condensation of vapours. There is a strong correlation between the deterioration processes and the dynamic changes room climate. The main factors which are responsible for historic elements deterioration are [10]:  Liquid Water: If drainage systems are not maintained properly or the envelope itself is damaged, rain or ground water may be able to enter the structure through penetration, infiltration or capillary action. The source of moisture is generally easy to be identified, simply by examining the distribution of damage in the building elements.  Water Vapor: Dampness is strongly correlated with high relative humidity and sudden temperature rise. When temperatures and relative humidity fluctuations are sharp, water vapour rises on the cold wall, ceiling or window surfaces and condenses, causing deterioration in paintings, surface elements of walls and stained glass.  Salt Activity: Hygroscopic salts are contained in different types of construction and artifacts. Levels

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. of hygroscopic salts are determined by relative humidity. As they have a particular equilibrium, when RH rises above that point the salt dissolves and usually moves into the porous structure of traditional building materials. So when RH decreases again the salt crystallizes and potentially disrupts the pores of materials, which are normally smaller than the crystals.  Microbiological growth: Microbiological growth, also known as bio-deterioration, can cause either physical disruption, as the micro-organisms colonise an area of the affected element, or chemical disruption, due to the by products, which are produced by the life-cycle of the microorganism.  Dimensional Change: Changes in humidity levels cause expansion and contraction of the cellular structure of wood. Especially painted elements, which consist of different layers of materials that are vulnerable to dimensional changes. As each layer expands by different percentage when humidity levels rise, stress can be caused across the structure resulting in delamination and flaking of wood. Historic fabric consists of porous materials and the whole structure is often characterized by high levels of porosity and air exchanges as a form of natural ventilation. As a result, the internal microclimate responds quickly to changes in external conditions. The historic structure quickly achieves a state of equilibrium with the ambient air. However, when modern heating / ventilation techniques are applied to historic structures this “moisture” balance between elements and ambient environment can be disrupted. [11]

3. THE PILOT RESEARCH 3.1. Methods employed As part of the Pilot research, two case studies were selected and surveyed. (Fig. 3) The case studies chosen were: I. A church with central gas boiler driving a water pipe under-floor heating system in constant operation (Great St Mary's university church in Cambridge, UK) II. A church with local electrical heating system intermittently operated. The case studies were chosen to evaluate the indoor environment and thermal comfort conditions occurring in the representative cases of constantly and intermittently heated large spaces and thus to extract conclusions on the effectiveness and suitability of environmental controls in each case. The final project will combine both quantitative and qualitative research methods. This initial pilot survey engaged only part of this methodology and it is the results of the pilot study that are presented here. Monitoring and site measurements took place between 26/02/2010 and 24/4/2010. Datalogger devices were installed around the churches to measure Temperature (ºC) and Relative Humidity (%) at different heights and locations.

Figure 3: Left: Gt St Mary’s church, Right: St Botolph;s church, Cambridge, UK

The assessment of thermal comfort levels is based on structured written questionnaires, consisting of close – ended questions, which were distributed to occupants during services. In the forthcoming academic year a Thermal Comfort Monitor will be used to produce scientific measurements of thermal conditions. The results will be analysed statistically to evaluate the current environmental performance of historic ecclesiastical structures and the potential for thermal comfort provision. In addition IR thermography method will be used to inspect the effect of heating strategies to the moisture content of several structural elements. The pilot research will also allow the case studies to be modelled using advanced simulation software to test possible alternative strategies for improving the indoor conditions. A similar method has been successfully employed by Geva (1998), to produce systematic analyses of the energy performance of historic structures. [12] 3.2. Results and Analysis The constant under-floor heating in Gt St Mary’s church, gives satisfactory levels of internal temperature and relative humidity, resulting in relatively comfortable indoor conditions (Tav.=16,30°C, RHaverage=59%). However, the internal space is not heated uniformly, i.e. there are several spaces, such as the chancel, and other ancillary areas which are not heated directly by the under-floor heating system. It is believed that vertical heating currents result in noticeable contrasts (2°C-3°C difference) between warmheated spaces and colder-unheated ones, creating a possible risk of condensation in colder areas. The second church (St Botolph’s) appears to be more efficient in terms of energy consumption, as it is heated only for limited periods during the week. However, the instantaneous local heating often fails to provide thermally-comfortable conditions, as most of the heat escapes to the top of the building to the cold ceiling, where rapid changes in temperature conditions, in combination with cold ceiling surfaces create a major risk of vapour condensation. (Fig. 4) In Gt St Mary’s church, because the central heating system is constant throughout the day, temperature fluctuation is rarely bigger than 1°C 2°C, while the relative humidity increases by approximately 5% during services. In St Botolph’s church, the temperature increases more rapidly during services, when the heating is turned on, and the micro-climate is disrupted. The sharp

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. fluctuations of temperatures in St Botolph’s church are more likely to cause the sort of wet and dry cycles at the ceiling level that according to Olstad (2001) [13] are responsible for dimensional changes and damage to painted wooden elements.

Figure 6: Relative Humidity occurrence in Gt St Mary’s and St Botolph’s

In summary, the locally-heated church provided very low temperatures combined with high relative humidity, while the constantly-heated church provided more acceptable, higher temperatures with more appropriate humidity levels. (Fig. 7) As the following graph illustrates, the results from Gt St Mary’s are less dispersed, while at St Botolph’s the results are more scattered and are more likely to cause intense heating-cooling cycles in the upper parts of the building, and thus excess moisture levels, which can lead to conservation problems. [8]

Figure 4: Temperature and Relative Humidity Fluctuation in St Mary’s and St Botolph’s church during a typical Sunday

Applying the thermal comfort criteria produced by CIBSE in 1980 [14], Gt St Mary’s church’s central constant heating seems to provide more satisfactory conditions than St Botolph’s local intermittent heating. Most of Gt St Mary’s temperatures during services in occupied areas lie e Occurence in occupied in areas the thermal comfort range (17°C - 13°C), while all temperatures occurring in St Botolph’s church lie ge of Temperature Occurence occupied areasof the following graph. (Fig. 5), in theinCold range suggesting that the local intermittent heating is simply not good enough to provide adequate levels of thermal comfort even when it is turned on. Percentage ofSt Temperature Occurence in occupied areas Mary's 1

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Similarly the relative humidity in Gt St Mary’s is within thermal comfort range, while in St Botolph’s the high relative humidity in combination with low temperatures often causes the air to feel chilly.[15] (Fig. 6) Research suggests that low comfort temperatures of 20°C combined with relative humidity 40% - 70% are likely to provide more pleasant conditions. [16] The following graph also shows that St Botolph’s internal fabric and artefacts are more vulnerable to deterioration. However, in St Botolph’s, the relative humidity of 80% - 95% should not cause mould growth as long as the temperatures do not rise above their current low levels. It is this conservation aspect of the problem, which is critical when studying the thermal comfort in historic churches as rapid changes in indoor relative humidity can be particularly detrimental.

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Figure 7: Temperature and Relative Humidity correlation in Gt St Mary’s and St Botolph’s

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The questionnaire survey results showed that occupants in both pilot studies felt generally cooler at head level. Only a very few occupants have stated that they felt too warm at head level, in St Mary’s church where the warm air coming from underfloor heating, next to, but not under the pews, rises and fails to provide the lower pew areas with warm air, thus creating a gradient, as relevant thermal comfort studies have shown. [6] This is rarely large enough to cause discomfort for St Mary’s occupants (because the constant heating creates almost uniform conditions). However, when virtually the same situation occurs in St Botolph’s church, where localised heating in the pews is used, thermal panels seem to be providing only small amounts of heat mainly at knee level leaving the upper parts of the body cold. (Fig. 8)

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. lie completely outside the thermal comfort zone as defined by the CIBSE guidance for the thermal comfort and optimum indoor conditions for public and commercial buildings. (Fig. 10 & 11)

Figure 8: Thermal Comfort distribution on feet and head level for Gt St Mary’s and St Botolph’s

Occupants answering the survey agreed that the performance of the heating system at Gt St Mary’s is satisfactory, (Fig. 9) while the St Botolph’s intermittent heating method has gathered more dispersed votes, which tended to rate the heating system as poorly performing.

Figure 10: Psychrometric chart for St Botolph’s church: Local Intermittent Heating

Figure 11: Psychrometric chart for St Botolph’s church: Local Intermittent Heating

Figure 9: Heating System Performance in Gt St Mary’s and St Botolph’s

4. DISCUSSION AND CONCLUSION This paper investigates the effectiveness and suitability of two representative heating strategies in historic church buildings in terms of (1) provision of thermal comfort and (2) provision of acceptable indoor conditions (Temperature and Relative Humidity levels) to protect fabric and artefacts from deterioration [4] The pilot survey has shown that neither strategy is wholly satisfactory from the conservation point of view, both raising issues of possible deterioration of the historic fabric, either by physical damage or by condensation, salt-activity or dimensional change when indoor conditions change rapidly. The other side of the equation is thermal comfort. Thermal conditions were investigated in both pilot studies and suggest that constant operation of heating offers more satisfactory levels of thermal comfort than intermittent local heating, although the energy consumption per capita appears to be higher. When the results were plotted in psychometric charts, to test if the perceived thermal comfort estimation based on occupants' responses agrees with the predicted thermal comfort based on the actual environmental conditions, most of the points laid within the thermal comfort zone for Gt St Mary's church (17ºC < T < 22ºC & 40% < RH < 70%), whereas the results from St Botolph's church

At the moment the majority of surveys within the UK and across Europe concentrate on conservation issues and suggest that environmental control systems should have the least possible impact on the micro-climate and serve occupants' needs as locally as possible. This paper suggests that this strategy – of intermittent localised heating – may not yield the best results and indeed may be positively detrimental while not achieving the thermal comfort levels required. In addition, any environmental control needs to ensure efficient usage of energy resources, if it is to meet the demand for limiting Climate Change. Therefore more research urgently needs to be done on the improvement of thermal comfort levels and energy conservation in historic buildings before inappropriate strategies are implemented, possibly putting historic buildings at risk. The work done so far raises three questions:  Presuming that the future of these buildings must lie in their continued use, how can they be heated satisfactorily without deterioration to the fabric?  If localised systems alone fail to provide comfort and are detrimental, what are the alternatives?  How can sustainable retrofit measures work together with conservation and thermal comfort requirements to limit current levels of energy consumption? The intention in the next part of the study is to use modelling to explore a wide range of environmental control strategies in more depth and suggest the most energy - efficient ones to be used in specific situations. Data collection through interviews and structured questionnaires and observations will

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. take place in a larger number of historic hall structures to gather sufficient samples of information to check the assumptions of the pilot study and produce suggestions for performance assessment and decision-making procedures for controlling the internal conditions in historic structures.

5. LIMITATIONS OF EXISTING STUDY AND FUTURE WORK As a final remark, there are some limitations of the study, which are acknowledged. Firstly the thermal comfort evaluation was generated by statistical analysis of the occupants’ answers to the questionnaire but no account was taken of clothing worn (clo = 1,2 assumed) or metabolic rate (1 Met assumed). Having carried out the pilot study, a more elaborate survey will be employed in the main study looking more widely at thermal comfort perception of individuals in public places to extract more accurate conclusions. Secondly, the pilot study is based fundamentally on environment data gathered by monitoring instruments and the conclusions on environmental performance are based on assumptions based on those individual measurements. The main study will check these measurements by expanding the number and variety of churches monitored and doing so over a longer period. In addition to create a better understanding of the conditions and air flows occurring in large hall spaces, each case will be modelled in simulation software. The computer model will then be used as the starting point to test possible adaptation scenarios.

[6]

[7]

[8]

[9]

[10]

6. ACKNOWLEDGEMENTS We would like to thank Professor Koen Steemers and Dr Nick Baker, for their valuable comments and suggestions during this study and for their continued interest in the research.

7. REFERENCES [1] Stern, N., 2006. Review on the Economics of Climate Change, UK: HM Treasury, [online]. Available from: http://www.sternreview.org.uk (Accessed on 15/10/2009) [2] CofE (Church of England) 2009, Shrinking the Footprint, Church and Earth 2009 – 2016, The Church of England’s Seven – Year Plan on Climate Change and the Environment, CofE, October 2009 [3] Carbon Trust, Introducing Local Authority Carbon Management, UK, April 2008, [online]. Available from: http://www.carbontrust.co.uk/ publications/pages/publicationdetail.aspx?id=C TX601 (accessed on 10/04/2010) [4] Bordass, W. and Bemrose, C., 1996. Heating your Church. London: Church House Publishing Ltd [5] CofE (Church of England) 2008. Shrinking the footprint, The Church of England’s National

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[11]

[12] [13]

[14] [15] [16]

Environmental Campaign, Guidance on Energy Efficient Operation and Replacement of Plant and Equipment, Deliverable D9 Carbon Management Programme, Church of England September 2008, [online]. Available from: www.shrinkingthefootprint.cofe.anglican.org (accessed on 10/04/2010) Camuffo, D. and Della Valle, A., 2007. Church Heating: A Balance between Conservation and Thermal Comfort, Contribution to the Experts, Roundtable on Sustainable Climate Management Strategies, held in April 2007, in Tenerife, Spain. The Getty Conservation Institute. Erhardt, D., Mecklenburg, M., Tumosa, C.S & McCormick-Goodhart, M., 1997. The determination of appropriate museum environment. In: Bradley S., eds., The Interface between Science and Conservation. London: British Museum, Occasional paper., 1997(116): p. 1 53 –163. Arnold, A. and Zehnder, K., 1987. Monitoring Wall Paintings Affected by Soluble Salts. In: The conservation of wall paintings; proceedings of a symposium organized by the Courtauld Institute of Art and the Getty Conservation Institute, London, July 13-16, 1987. pp. 103-135 Massari, G. and Massari, I., 1985. Damp Buildings, Old and New, Bulletin of the Association for Preservation Technology, Association for Preservation Technology International (APT), 17 (1): 2-30 Curteis, T., 2004. Environmental Conditions In Historic Churches: Examining Their Effect On Wall Paintings And Polychrome Surfaces, Transactions of the Ecclesiastical Architects and Surveyors’ Association, 5 (2004). pp. 36 – 46 Camuffo D., Sturaro G., Valentino, A., Camuffo, M., 1999. The Conservation of Artworks and Hot Air Heating Systems in Churches: Are They Compatible? The Case of Rocca Pietore, Italian Alps, Studies in Conservation, 44 (1999): 209216 Geva, A., 1998. Energy Simulation of Historic Buildings: St Luis Catholic church, Castroville, Texas. APT Bulletin, 29 (1): 36-41 Olstad, T.M., Haugen, A., Nilsen, T.N., 2001. Polychrome wooden ecclesiastical art - Climate and dimensional changes, Oslo: NIKU Publications, pp.1 - 24 Brundrett, G.W., 1990. Criteria for Moisture Control. London: Butterworth & Co. Ltd McMullan, R., 2002. Environmental Science in Building, Fifth edition, Hampshire and New York: Palgrave Macmillan Olesen, W., Schøler, M. and Fanger, P.O. 1979. Discomfort caused by vertical air temperature differences. In: P.O. Fanger and O. Valbjørn, eds., Indoor Climate, Copenhagen: Danish Building Research Institute

BUILDING PHYSICS (DAYLIGHTING)

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Daylight performance assessment and design strategies in the adjoining spaces of atrium buildings Jiangtao DU1, Steve SHARPLES2 1

School of Architecture, University of Sheffield, Sheffield, UK

2

School of Architecture, University of Liverpool, Liverpool, UK

ABSTRACT: Daylight use in an atrium is particularly beneficial as the natural light can illuminate potentially dark core areas and decrease energy consumption. This study has investigated, for overcast sky conditions, the vertical daylight levels on atrium well walls and the horizontal daylight levels in adjoining spaces in atria. The daylight levels in the rooms and on the walls were derived from scale model measurements, theoretical calculations and predictions from the lighting simulation package Radiance. A comparison of the three data sets showed generally good agreement. Some limitations in the calculations used in determining the daylight factors in rooms with large window area to total wall area ratios were observed. In terms of the well geometry and well façades (decided by the ratio of window area to solid wall area) and well surface reflectance, the variations of daylight level in the adjoining rooms have been analysed and some design strategies for supporting preliminary design decisions are presented. Keywords: atrium, well wall, adjoining spaces, daylight performance, design strategies

1. INTRODUCTION Daylighting is one of the most significant environmental advantages an atrium can bring to a building. The natural light from the atrium well can not only decrease artificial lighting use but also improve the interior on psychological and ergonomic grounds. According to two reviews [1, 2], the daylight levels in the adjoining rooms are significantly influenced by the vertical daylight levels on the well wall and the room properties (size and surface reflectances). The well geometries and surface reflectances are very important atrium characteristics which have a direct effect on the vertical daylight levels [3, 4]. The reviews [3, 5] indicated that much of the research investigating daylight in atria has tended to focus upon illuminance levels on the atrium well floor. Studies relating to daylight levels in adjoining rooms and on well walls are less common. Two studies [6, 7] suggested changing the proportion of glazing or open areas between well and adjacent spaces could be a practical solution to the imbalance of light flux received at the top and bottom of the atrium walls and adjoining spaces. Based on a twostage concept [1], Aizlewood et al [8] and Degelman et al [9] have developed theoretical approximations to predict the average daylight levels in the adjoining spaces from the known vertical daylight levels on the window wall. A study [10] also analysed the impact of atrium characteristics on the daylight levels of rooms at ground floor level in atria using numerical simulations. In most of these investigations the geometric and reflectance ranges of the atrium models studied were rather narrow. Most of the atrium models just had a specific plan (square or linear), while their shapes were defined by the various heights. Some measurements only focus a

small number of typical surface reflectances. Moreover, the theoretical approaches that were developed and their applications need more testing. It is still important to carry out more investigations for a broader range of parameters to get more detailed information which could effectively support preliminary design practice. This study utilized Radiance as a simulation tool for the calculations of daylight factors in atria. Firstly, a comparison between model measurements and Radiance simulations was undertaken to validate the Radiance outputs. Next, more simulations were carried out to test the application of an analytical theory. Thirdly, the impact of atrium shapes and surface configurations on the average daylight factors in rooms was considered. Finally, some design strategies have also been developed.

2. ATRIUM GEOMETRY The atrium geometry [1] can be quantified in terms of the well index (WI), which is a function of well length (l), width (w) and height (h). The other two factors are plan aspect ratio (PAR), which just relates to well width (w), and well length (l) and section aspect ratio (SAR), which is the ratio between well width (w) and well height (h). The equations are: h w h( w + l ) SAR = PAR = WI = w 2 wl l (1); (2); (3).

3. MEASUREMENT AND SIMULATION A physical atrium model (scale: 1:40) was used in a mirror box artificial sky that reproduced a CIE standard overcast sky. The measured data were compared with the simulated data by Radiance. The scale building model had an atrium well and adjoining spaces (Fig.1). In the centre of the building

xx.x SECTION NAME

BUILDING PHYSIC (DAYLIGHTING)

1

765

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

the atrium well had a square plan of 200mm × 200mm whilst the whole building had a square plan of 500mm × 500mm. With a height of 350mm the atrium well had a WI value of 1.75, which represents a medium atrium. Four-storey adjoining spaces were set around the well and the height and the depth of each side room at each floor were 70mm and 150mm respectively.

point; 3, 75% point. Other points at other floors follow this sequence so numbers 1, 4, 7, 10 are the positions near the well while numbers 3, 6, 9, 12 are the positions near the back wall. Fig. 2 shows the comparison of measurements and simulations at these positions. It can be seen that, generally, the simulations agree with the measurements, especially at the ground floor and the positions at a greater distance from the well. Taking the measured value as reference, the average relative difference between the results is around 12%. The larger divergence occurs at the first floor and second floor for positions near the well. This might be explained by the geometric and photometric deviations between the physical model and the Radiance model. However, the general trends in the data still indicate the validation of the Radiance simulation.

4. SIMULATION AND THEORY A theoretical formula developed in an earlier study [8] was used for the calculation of the ratio of average daylight factor (DFavr) in rooms to the vertical daylight factor (DFw) at the centre of the window. The original equation is given as:

DFavr =

2 AwTi DFw Ar (1 − Rr2 )

(4). Then, the ratio between them can be derived as:

DFavr 2 AwTi = DFw Ar (1 − Rr2 )

Figure 1: Scale atrium model in a mirror sky.

Photocells were positioned along the centre line of the rooms at one side of the square plan. There were twelve points altogether and each floor had three photocells. For each floor, the distances of the measured positions to the border of well were 25%, 50% and 75% of room depth (150mm) respectively. The top surfaces of the photocells were level with the working plane (20mm) in the room of each floor. 18

M-g S-g M-1 S-1 M-2 S-2 M-3 S-3

16

Daylight Factor (%)

(5). where Aw is the area of the room’s windows and Ti is its visible transmittance. Ar is the total area of the room’s surface and Rr is the surface’s area-weighted reflectance. In this study the theoretical calculations of the ratio in a number of atrium models were compared with simulated data from Radiance. The atrium models studied were used with a broad array of WI (0.9 to 2.2). Well surface reflectance (solid part) ranged from 0 to 0.8. The adjacent rooms had a fixed ceiling reflectance of 0.8, a wall reflectance of 0.5 and a floor reflectance of 0.25. In addition, all the models were divided into four groups in terms of the façade/balcony type - see Fig. 3 where (a) = window with no balcony; (b) = 1/4 room height balcony; (c) = 1/3 room height balcony and (d) =1/2 room height balcony.

14 12 10 8 6

(a)

4

(b)

2 0

0

1

2

3

4

5

6

7

8

9

10

11

12

13

Position No.

Figure 2: Comparison of measured (M) and simulated (S) data at the three positions of each floor (g: ground floor; 1: 1st floor; 2: 2nd floor; 3: 3rd floor) in an atrium model.

The positions on the ground floor can be expressed by the numbers: 1, 25% point; 2, 50%

xx.x SECTION NAME 7662 BUILDING PHYSIC (DAYLIGHTING)

(c)

(d)

Figure 3: Four different types of façade.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

(rooms in the lower positions near the base). The divergence starts from vertical daylight factors above 20% and increases with increasing daylight levels at the window. The regression equation of the simulated data is:

Models with opening window

Average DF in the room

18 16 14 12 10 8

DFavr = 0.19 DFw

6

simulation theory

4 2 0

0

20

40

60

80

Vertical DF on the window Models with 1/4 balcony

Average DF in the room

14 12 10 8 6 4

simulation theory

2 0

0

20

40

60

80

Vertical DF on the window Models with 1/3 balcony

Average DF in the room

12 10

(6). The theoretical expression of the open window models is: DFavr = 0.24 DFw (7). The deviations from these models might occur because some reflected light in the room escapes from the opening. The other linear relationships between the two daylight factors are expressed as: (8); 1/4 balcony: DFavr = 0.18 DFw 1/3 balcony: DFavr = 0.16 DFw

(9);

1/2 balcony: DFavr = 0.12 DFw

(10).

The equations demonstrate that the higher balconies block more received light in the rooms even though they might increase the reflected light from other façades. Radiance simulations can be seen to be a valid tool from the agreement with the theoretical data.

5. DF IN ADJOINING ROOMS

8

Radiance simulations were used to investigate the impact of well geometries and surface configurations on the average daylight factors in the adjoining rooms for a range of atrium properties.

6 4

simulation theory

2 0

0

20

40

60

80

room

Vertical DF on the window

well

room

Models with 1/2 balcony

Figure 5: General plan of atrium models.

Average DF in the room

9 8 7 6 5 4

simulation theory

3 2 1 0

0

20

40

60

80

Vertical DF on the window

Figure 4: Comparisons of theoretical calculations and Radiance simulations in models with four different facades.

Fig. 4 compares theoretical calculations and Radiance simulations in models with different window areas/balcony heights on the well façade. Most of the simulated data agree well with the theoretical calculations from equation (5), except for the models with an open, unobstructed window. There is a clear linear relationship between the vertical daylight levels on the window and the average daylight levels in the adjoining rooms off the atrium well. The slopes of the lines relates to the room size and room surface reflectances. For the models with no balcony the theory data are close to the simulations for vertical daylight factors < 20%

All atrium models consisted of a seven-story building with a centre well and two sides rooms (Fig. 5). The well had two different plans: square and rectangular. The WI value of the seven-story square atrium was 2.17, which is a deep atrium. The rectangular models were expressed by four different PAR values (0.8, 0.67, 0.5 and 0.4) and one fixed SAR (2.17). The solid part of the well had reflectance values of 0, 0.2, 0.4, 0.6 and 0.8.The rooms had a fixed ceiling reflectance (0.8), wall reflectance (0.5) and floor reflectance (0.25). Similar to Section 4 and Fig 3, four facades were used in the models. 5.1. Square models With a WI = 2.17 and square plan the models had various façade types and well surface reflectances. Fig. 6 shows the variations of average daylight th factors on the top floor (6 floor). It is apparent that the increased well reflectance increases the ADF (average daylight factor) in rooms. The higher balcony reduces the incident light for the rooms, giving a lower ADF. The 1/2 balcony room had the least daylight. The daylight level in the 1/4 balcony room was similar to the room with no balcony. Interestingly, the daylight factors decease at a

xx.x SECTION NAME

BUILDING PHYSIC (DAYLIGHTING)

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767

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

proportionally greater rate than the increase in the height of the balconies. Fig. 7 expresses the variations of average daylight factors on the middle rd floor (3 floor). Again, increased well reflectances Top floor 9 8 7 6

opening 1/4 balcony 1/3 balcony 1/2 balcony

5 4 3 2 1 ref0

ref0.2

ref0.4

ref0.6

ref0.8

Well surface reflectance

Figure 6: Variations of ADF in top floor rooms with four facades and different well surface reflectances. Middle floor Average daylight factor (%)

3.5

5.2. Rectangular models

3 2.5 2

opening 1/4 balcony 1/3 balcony 1/2 balcony

1.5 1 0.5 0 ref0

ref0.2

ref0.4

ref0.6

ref0.8

Well surface reflectance

Figure 7: Variations of ADF in middle floor rooms with four facades and different well surface reflectances.

Ground floor Average daylight factor (%)

1.8

9 8 7 6 5 4 3 2 1 0

PAR 1

PAR 0.8 PAR 0.67 PAR 0.5

PAR 0.4

Plan aspect ratios

1.4

Short side (top floor)

1.2 1

opening 1/4 balcony 1/3 balcony 1/2 balcony

0.8 0.6 0.4 0.2 ref0

ref0.2

ref0.4

ref0.6

ref0.8

Well surface reflectance

Figure 8: Variations of ADF in ground floor rooms with four facades and different well surface reflectances.

increase the ADF in the rooms. Also, the varying trends among the different curves are similar to the top floor. The slopes of the curves are much steeper than those of the top floor, which means increased magnitudes of DF by increasing reflectance are larger than those for the top floor. For example, the relative difference between refl0 and refl0.8 of the open window and 1/2 balcony on top floor are 24% and 27% respectively, whilst the two values have increased to 85% and 140% on the middle floor. This

4

Long side (top floor)

1.6

0

768

With a SAR=2.17 (see equation (3)) the rectangular models had various PAR (see equation (2)) values (0.8, 0.67, 0.5 and 0.4) and façade types and well surface reflectances (including well wall, floor and external side of the room balcony). Average daylight facor (%)

0

xx.x SECTION NAME

BUILDING PHYSIC (DAYLIGHTING)

Average daylight factor (%)

Average daylight factor (%)

10

demonstrates that for the middle the rooms receive more reflected light from the well surface. In addition, the curves of the 1/3 balcony tend to approach the curves of the open window and the 1/4 balcony, which implies that the impact of the lower balcony height is decreasing at the middle floor. Fig. 8 shows the variations of average daylight factors on the ground floor. All the patterns of ADF variations are very similar to the middle floor. However, the two shorter balconies do not significantly influence the daylight levels in rooms at ground floor – only the 1/2 height balcony is having a detrimental impact. The slopes of the curves have become much steeper than the curves of the middle and top floors. For example, the relative difference between the ADF for refl0 and refl0.8 of the open window and 1/2 height balcony at ground floor are 253% and 490% respectively. This means that the changing magnitudes of ADF for various reflectances are much larger at the ground floor. This might be due to the fact that the main components of ADF at deeper positions in atria consist of reflected light.

9 8 7 6 5 4 3 2 1 0

PAR 1

PAR 0.8 PAR 0.67 PAR 0.5

PAR 0.4

Plan aspect ratios

Figure 9: Variations of ADF in rooms on the two sides of the top floor of atria with 1/3 height balcony and different well surface reflectances and PAR values.

Fig 9 displays the variations of average daylight factors in rooms on two sides of the top floor in atria with 1/3 height balconies. For the room on the long side of the top floor the ADF values slightly increase with the decreasing PAR; for the room on the short side of the top floor, the ADF does not clearly vary

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

with a changing PAR. Only the higher well reflectances (0.6 or 0.8) can bring a little impact. This suggests that on the top floor the stretched well space could take more sky light to the rooms of the long side, but the rooms on the short side do not receive significant more sky light compared with the square well. The increasing well reflectances increase the daylight factors in rooms on both sides.

4.5 4 3.5 3 2.5 2 1.5 1 0.5 0

Long side (ground floor)

PAR 1

Average daylight factor (%)

Average daylight factor (%)

Long side (middle floor)

rooms on both sides of the middle floor – as the PAR values get smaller the daylight levels in the rooms get bigger. The rooms on the short side have a proportionally greater increase in ADF with the decreasing PAR than the rooms on the longer side. Comparatively, the increasing rate of ADF in rooms on the ground floor is much larger than the changes in rooms on the middle and top floors. For the ground floor the average relative differences between PAR1 and PAR0.4 for the short side and long side are 142% and 89% respectively.

PAR 0.8 PAR 0.67 PAR 0.5 PAR 0.4

Plan aspect ratios

3 2.5 2 1.5 1 0.5 0

PAR 1

Short side (ground floor)

Average daylight factor (%)

Average daylight factor (%)

6 5 4 3 2 1 0

PAR 0.8 PAR 0.67 PAR 0.5 PAR 0.4

Plan aspect ratios

Short side (middle floor)

PAR 1

PAR 0.8 PAR 0.67 PAR 0.5

PAR 0.4

Plan aspect ratios

Figure 10: Variations of ADF in rooms on two sides of the middle floor of atria with 1/3 height balcony and different well surface reflectances and PAR values.

Fig 10 indicates the variations of average daylight factors in rooms on two sides of the middle floor in atria with 1/3 height balconies. In contrast to the variations on the top floor, the rooms on the long and short sides of the well express a similar varying trend of ADF. The decreasing PAR will tend to increase the daylight levels in the rooms. The rooms on the short side, however, will get a proportionally greater increase than the rooms on the long side. For instance, the average relative difference between PAR1 and PAR0.4 for a room on the short side is 62%, whilst the value for a room on the long side is 50%. For both sides, with the increasing well surface reflectances, the ADF values increase and the increasing magnitudes between two adjacent curves increase proportionally. Each curve for the long side expresses a parallel trend with others in the whole PAR range. However, the slopes of the curves on the short side increase with increasing reflectance. This shows that the rooms at the middle positions of the short wall are more easily influenced by the stretched well length. Fig 11 expresses the variations of average daylight factors in rooms on the two sides of the ground floor in atria with 1/3 height balconies. The variations of average daylight factors in rooms on both sides of the ground floor are very similar to the

4 3.5 3 2.5 2 1.5 1 0.5 0

PAR 1

PAR 0.8 PAR 0.67 PAR 0.5 PAR 0.4

Plan aspect ratios

Figure 11: Variations of ADF in rooms on two sides of the ground floor of atria with 1/3 height balcony and different well surface reflectances and PAR values. Table 1: Average daylight factors in rooms on the long side of the middle floor with open window and different well surface reflectances (R) and PAR values. PAR1

PAR0.8

PAR0.67

PAR0.5

PAR0.4

R 0

1.63

1.91

2.12

2.46

2.7

0.2

1.87

2.17

2.4

2.74

2.97

0.4

2.17

2.47

2.71

3.04

3.26

0.6

2.53

2.86

3.09

3.39

3.59

0.8

3.01

3.31

3.53

3.81

3.97

Table 2: Average daylight factors in rooms on the long side of the middle floor with 1/2 height balconies and different well surface reflectances (R) and PAR values. PAR1

PAR0.8

PAR0.67

PAR0.5

PAR0.4

R 0

0.97

1.12

1.27

1.47

1.61

0.2

1.16

1.35

1.49

1.71

1.85

0.4

1.40

1.62

1.78

2.00

2.15

0.6

1.76

2.00

2.17

2.41

2.56

0.8

2.33

2.58

2.77

3.00

3.15

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BUILDING PHYSIC (DAYLIGHTING)

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769

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 1 and Table 2 indicate the variations of average daylight factors in rooms on the long side of the middle floor in atria with an open window and atria with a 1/2 height balcony respectively. It can be seen from the data that the variations of ADF in rooms with various windows and balconies are very similar. The only difference is the absolute values of ADF. Generally, the rooms with the higher balconies get the lower daylight levels.

6. DESIGN STRAGETIES Based on the results and discussions above, some suggested strategies for supporting daylight design in the adjoining rooms of atria are: (i). The average daylight levels in the adjoining rooms have a linear relationship with the vertical daylight level on the centre facade of the floor. The former can be derived from the latter using equation (4). However, when full windows are used at the well side, the calculated result should be multiplied by a value of 0.8. (ii). High balconies can block direct sky light and reflected light on different floors in atria whilst low balconies do not have much effect on the incident light. Medium balconies will only block the direct sky light on the top floor. On the ground floor no significant reflected light is obstructed by the medium balconies. (iii). For a given SAR (a fixed atrium height), decreasing the PAR value of the atrium well would increase the average daylight factors in rooms at middle and low positions in the atrium. The rooms on the short well wall have a proportionately bigger increase in ADF than the rooms on long well wall. (iv). For the rooms near the top of the atrium changing the PAR value of the atrium well would not significantly change the average daylight factors in rooms at different positions because they are dominated by the sky component. (v).Increasing the reflectance of the well surfaces of an atrium could improve the average daylight factors in the rooms. As the reflectance values are increased incrementally the average daylight factors increase at a proportionally greater rate.

7. CONCOLUSIONS This study has investigated the average daylight levels in the adjoining spaces and vertical daylight levels at the centre of windows in atria. Validated by measurements and theory, Radiance, a ray-tracing package, was used to calculate the daylight factors for a wide range of atrium geometries and reflectances. The theory used for calculating average daylight factors in rooms was also tested and a few small limitations have been found. The impact of atrium geometries, well façade configurations and well surface reflectances on the average daylight levels in adjoining rooms has been assessed through Radiance simulations. Based on the results, some design strategies have been suggested.

6

770

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8. REFERENCES [1] M. Aizlewood, “The daylighting of atria: a critical review.” ASHRAE Transactions 101(1995), 841857. [2] P. Littlefair, “Daylight prediction in atrium buildings.” Solar Energy 73(2002), 105-109. [3] S. Sharples and D. Lash, “Daylight in atrium buildings: a critical review.” Architectural Science Review 50(2007), 301-312. [4] J. Du and S. Sharples, “Computational simulations for predicting vertical daylight levels in atrium buildings.” Proc. of Building Simulation 2009, Glasgow – UK (2009). [5] J. Wright and K. Letherman, “Illuminance in atria: review of prediction methods.” Lighting Research & Technology 30 (1998), 1-10. [6] R.J. Cole, “The effect of the surfaces adjoining atria on the daylight in adjacent spaces.” Building and Environment 25(1990), 37-42. [7] M. Aizlewood, K. Isaac and P. Littlefair, "A scale model study of daylighting in atrium buildings", Proc. of the IESANZ, Perth – Australia (1996). [8] L. Degelman, J. Molinelli and K. Kim, "Integrated daylighting, heating and cooling model for atriums", ASHRAE Transactions 94(1988) 812825. [9] Ø. Aschehoug, “Daylight in glazed spaces.” Building Research & Information 20(1992), 242245. [10] B. Calcagni and M. Paroncini, “Daylight factor prediction in atria building designs.” Solar Energy 76(2004), 669-682.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Daylight and solar control in building: a new angle selective see-thorough PV-façade for solar control Francesco FRONTINI1 1

Fraunhofer Institute for Solar Energy sytems ISE, Heidenhofstr. 2, 79110, Freiburg, Germany

Abstract: In a World more and more concerned about carbon emissions, global warming, and sustainable design, the planned use of natural light in buildings and the design of good solar control façade has become an important strategy to improve energy efficiency by minimizing lighting, heating and cooling loads. Buildings account for almost 40% of overall energy consumption. The majority of this demand is due to the energy needed to provide sufficient indoor comfort. In addition electricity is required for artificial lighting and equipments. But fortunately it has been shown by various projects that especially new buildings are able to become a neutral energy balance on an annual basis (“net-zero-energy buildings”). To produce the same amount of energy, using renewable energy sources, as it consumes during the entire year, significant reduction in energy consumption and the use of renewable or nonfinite energy sources are required. As result building envelop becomes really important as it provides the necessary area for the installation of the collectors. An example of a new multifunctional angle selective glazing PV façade is here presented. It combines in one-element four important tasks: solar protection, glare protection, visual contact and integrated PV-system for electricity production. These four elements, as are completely integrated in the function of the façade, do not reduce the architectural goal of the glazed façade and the view from the interior to the exterior is guaranteed. RADIANCE simulations are carried out to assess the visual contact and the daylight level in office space. The paper shows the capability of this new system together with the building integration. Keywords: Daylight, Solar control, BIPV, Photovoltaic, Simulation

1. INTRODUCTION In 2009 the regulatory framework and the business environment for the construction sector has changed significantly in order to reduce the CO2emissions of existing and new buildings. It is now officially agreed within Europe that Net-Zero-Energy buildings are the goal for the future. For the renovation of existing buildings a net-zero energy balance is not mandatory, but the reduction of the annual primary energy balance is the target. In order to achieve this goal, we have to do two things: ƒ to increase the efficiency, especially in case of existing buildings; ƒ to cover the remaining energy demand with renewable sources. In case of single family houses and large single or double-storey factory buildings with flat roofs it might be sufficient to use only the roof of the building for renewable energy conversion. But for many other buildings with relatively small roofs it will be necessary to use also the façade for energy conversion in addition to the roof in order to achieve a net-zero energy balance. This is especially the case for multi-storeys buildings. Solar energy could be utilized in buildings in several ways. Often we differentiate between two main ways to utilize solar energy. Either by letting the solar radiation transmits through windows to passively contribute to space heating and offer daylight that could reduce the electricity need for lighting. Or by using active solar systems on the building envelope to produce solar heat and electricity that could be used to reduce the building’s need for non-renewable energy supply. Passive solar gains are part of the building’s energy balance. Passive solar gains can have both

positive and negative impacts as they can reduce heating and lighting demands together with cooling demands and the risk of glare is a possibility. Windows are used in most buildings and often well integrated in the building envelope. Shading devices are in many regions also frequently used even if there are regional differences both regarding the need and the tradition of using them, which sometimes could be improved. Active solar systems are sometimes integrated in new buildings as well as put on existing buildings to produce hot water or electricity. Most existing solar collectors are developed as purely technical elements, starting from the “energy production” point of view only, sizing the collectors to optimise energy collection, manufacturability, handling and installation, but only giving a marginal attention to architectural integration issues. Collectors must be developed to respond to their own technical constraints, but should furthermore become architectural elements, easy to integrate into the building envelope. They should possibly fulfil more than one function, consequently supporting designers’ integration efforts and reducing the overall cost. In this paper a new See-Through Integrated PVEnvelop system (STrIPe) is presented. BIPV systems offer many advantages compared to adding a PV system onto an existing building. BIPV systems: ƒ Require no additional support structures because they use the building’s frame (structure) ƒ Have limited additional construction expenses

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Can be designed to provide also daylighting, heat control, and other benefits Are designed in an aesthetically appealing manner to maximize visibility or educational impacts. Can be financed as part of the entire building

Figure 1: On the left: schematic view of the new seethrough, angle-selective façade. The stripes (represented in blue) can be produced with photovoltaic technology.

The new system (Figure 1) is a static, transparent glazing façade, which can be produced using the usual production technologies for windows and glazing units. It is easily installable in conventional double or triple glazing unit. Due to the different refractive indices of air and glass together with the specific position of the opaque stripes on the glass, the new façade offers high solar control and can protect the occupants against glare. The visual contact to the outside is also guaranteed and varies with the viewing direction. The opaque stripes can be produced in different materials or colours, depending on the architectural concept and on the shading requirements: dark colours are favoured to maximize the shading and anti-glare performance. The invention (patent application n° DE 10 2007 013 331 A1, submitted by T. E. Kuhn - FraunhoferISE) can be implemented with photovoltaic stripes on either the outer and/or the inner layer. The electrical efficiency of the system strictly depends on the design and on the technology adopted in the construction.

2. VISUAL CONTACT, GLARE AND SOLAR CONTROL PERFORMANCES OF THE SYSTEM A mathematical analysis and Radiance [7] simulations were carried out by the author to optimize the geometry and to assess the visual transmittance and the optical properties of the new window (see [4] for further details).The stripes dimensions and the glass thickness were varied to maximize the visual contact from the inside to the outside [6]. The main viewing angles are considered to be in the range of − 35° ≤ φ ≤ 20° , where negative angles represent the downward viewing direction and positive angles the upward one. A detailed description of this analysis can be found in [4] and [6]. Only the final structure is presented here together with the architectural integration and the installation details. The new façade was modelled in Radiance as a dielectric box (see [7] for a further description of the dielectric material in Radiance) with opaque stripes. The stripes were described as a plastic material. To asses the visual contact, a cellular office space was considered. The simulations presented in [4] reveal the good transparency of the system in particular in the lower area of the façade. As the following picture shows (Figure 2) this is due to the angle dependent transmittance of the system. The angle-dependent transmittance ( τ ang ) was determined from laboratory measurements and Radiance simulations. The angle-dependent total solar energy transmittance (g-value, [2]) of the new façade was simulated with the GWERT program developed by S. Kühn [7]. To allow the measurements and to validate the simulations, a prototype was produced in collaboration with a German glazing industry partner (the angle dependent light transmittance is shown in Figure 2). The simulations reveal the good performance of the new façade concerning visual contact to the outside (more than 30% transparency for downward viewing) and solar control (the effective g-value of the new façade can be less then 10%, Table 1).

Figure 2: Photos of the first prototype. The angular dependency transmission is shown tilting the prototype from -30° on the left (very high transmission) to +30° (the façade is more or less opaque).

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Table 1: The table reports the angle-dependent direct transmittance of the system and the angle-dependent total solar energy transmittance (for a solar azimuth of 0° with respect to the normal to the vertical façade). The solar altitude and positive viewing angles are identical by definition. A double glazing unit with Argon gap is considered.

60°

Viewing angles (positive upward, negative downward) and solar altitude 45° 30° 15° 0° -15° -30°

-45°

τ ang

< 0.01

< 0.01

< 0.01

0.05

0.12

0.19

0.24

0.22

gvalue

< 0.05

0.06

0.06

0.07

0.14

0.20

0.25

0.23

Figure 3: The pictures present an idea of the integration of the new façade as an extra construction. The external pane can slide among the façade changing the visual and solar transmission depending on the performance the users want to achieve.

Figure 4: The picture presents an idea of the integration of the new façade as external shading device. The external pane can slide among the balcony. The user can move it to change the solar protection and the view to the outside.

Figure 5: The picture presents an idea of the integration of the new façade in the normal window. The new window pane can tilt over a certain angle (>35°) to change the visual and solar transmission depending on the performance the users want to achieve.

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Within the program “Evalglare” (implementing a new method for the Daylight Glare Probability, DGP, which is described in [10]) the glare protection of the system was evaluated. The new DGP index is considered. DGP is a function of the vertical eye illuminance as well as the glare source luminance, its solid angle and its position index. Three different simulations were carried out by the authors in order to compare the new systems (Design 1 and 2) with a conventional glazing façade with external venetian blind (Design 3). ƒ Design-1 is a fully glazed façade with the new angle-selective façade covering 100% of the window; ƒ Design-2: the 70% of the external façade is covered by the new system and the upper part is transparent. While the conventional system reveals different glare sources due to the blind position (the slat angle of the blinds is considered to be fixed at 35°) with a critical DGP value (more than 40%), the other two systems provide good glare protection (e.g. the design 1 has a DGP1=0.22) (more details about the DGP simulation can be found in [4]).

3. BUILDING INTEGRATION Despite the fact that several parts of the building skin are suitable for the integration of active solar systems, a great potential of utilizing solar energy in architecture is still unused. There are several reasons for this situation, covering economical, technological and architectural issues. The research community is moving to this direction: find out a way for good solar energy technology building integration. The International Energy Agency launched the Task 41 titled Solar Energy and Architecture (http://www.iea-shc.org/task41) that gathers researchers and practitioners to focus on the latter by developing guidelines for architects and recommendations for manufacturers to help instigate the wide spread of high quality architecture and efficient solar buildings; the European commission lunched several project in the Seventh Framework program, like for example the EU-Cost Effective (www.costeffective-renewables.eu) project that was launched on October 1st 2008. The main focus of the project is to convert facades of existing “high-rise buildings” into multifunctional, energy gaining components. It is in the framework of this project that the new angle selective faced was developed.

internal comfort, the office space and the windows (Figure 3). Especially for open space office or airport hall, the new façade integrated with PV technology can be installed instead of double or triple glazing façade. If it is coupled with another glass pane and filled in with gas e.g. argon gas the new system has very height performances: ƒ low solar transmission (effective g-value less than 10%), ƒ visual contact to the outside, ƒ good daylighting, ƒ electricity production. Both in residential and in office buildings the façade can be used as external movable shading device (Figure 3, Figure 4) in order to protect the windows area when the sun is shining (especially during summer period). This solution has the advantage to let the users decide when they need more solar protection and in mean time to have full transparency when the shading system is retracted. Maintenance cost has to be taken into account together with the control strategies of the system. This solution needs also accurate technological design in order to allow it to slide among the windows. Figure 5 shows another integration possibility: the BIPV system replaces the existing windows and can be tilted by the user to let the fresh air coming into the building and to increase the transparency of the window. In this case the system completely replace the existing building element reducing on the same time the g-value and the transmission of the glazing system, no extra costs have to be considered. In order to leave part of the façade area fully transparent, as requested by the user (to have a direct contact with the surround), it is suggested to install the STrIPe in just part of the windows, as shown afterward, replacing the remaining glazing systems with high performance glass. This is the case of small office space where the occupants are really close to the external façade and the black stripe of the system can disturb the view quality.

3.1. Façade integration The new angle-selective façade can be used either as a stand-alone system for a glazed façade or as an extra shading device layer. It is thought mainly for retrofitting. In this paper different façade designs and different integrated concepts will be present in order to give an idea of the capabilities of the new system. The STrIPe façade can be either installed into existing building, just replacing the existing windows or into new buildings. The new PV façade can be installed as sliding external shading device to protect, depending on the

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Figure 6: the new façade can be easily installed in airport spaces or big open spaces. The picture shows an example of the façade installed in a complete glazed façade of a big open space (e.g. airport hall).

4. BUILDING SIMULATIONS Thermal simulations with ESP-r [1], modified to allow the modelling of such complex glazing systems ([3] and [5]), and Daysim/Radiance simulations (see

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

www.daysim.com and [8]) were performed to evaluate the optimum position of the new system in the glazing façade. The thermal behaviour and the daylight level (daylight autonomy and glare) of an office space were assessed. Different sizes of openings were simulated. There is no pat answer to this question, it depends on the function of the room and on the user tasks, for this reasons only qualitative results will be here presented. 4.1. Model description Six different façades were considered in order to asses the contribution of each glazing system and find out the optimum one (see Figure 7). The glazing systems were changed between normal low-e glazing ( τ vis = 73% and g win = 60% ) and the new STrIPe façade.

Figure 7: Six different façade designs were considered. Table 2: Geometry description

Type

Office

Net Floor Area [m²] 17.00

Room height [m] 2.85

Façade surface [m²] 10.30

Transparent area [m²] Different (A,B,C,D,E,F)

The Annual simulations were carried out for the location of Frankfurt (DE) (Lat: 50.10, long: -8.36) and the working hours are considered to be between 8:00 AM and 6:00 PM. Two working areas were placed at 1.0m from the window and facing each other. 4.2. Results The simulations reveal the importance of designing correctly the external glazing façade in order to have a good balance between the different comfort metrics (daylight autonomy, glare protection and the visual contact) together with the energy performances of the systems (solar protection and electricity production). The first simulated design (design A in Figure 7) has a fully glazed façade covered by the new angle selective façade with integrated PV. This configuration (treated as start case) has the highest solar protection (façade gvalue of about 10%) together with the optimum glare control (DPG less than 0.24). As the full façade is covered by photovoltaic element it also has the

highest electricity production index (see Table 3). On the other hand the visual contact from the inside to the outside is not enough and the daylight autonomy (DA) during the whole year is always less than 40%, that means that during 60% of the working hours the luminaries must be switched on to reach an internal illuminance of about 300 lux (benchmark for this study). For all the other designs (B, C, D, E and F) the natural lighting entering the room is higher during the whole year, differences are in the visual contact from the inside to the outside and on the Glare protection. As the window in the parapet level (design C) does not provide light in the depth of the room it is possible to leave the lower part of the façade semitransparent with the new system, also because the visual transmission downward is more than 30% and let the occupants see through. A window of equal dimension at mid-height position provides much light to the front (task position) of the room but does not deliver sufficient light to the rear. For this reason it is proved a good solution to leave the upper part of the façade transparent (design B). A good balance is reached with designs D, E and F. The area close to the windows is normally too bright (glare). Local anti glare screen (like internal rolling blinds) can be used to prevent glare on the task positions and an accurate office design must be planned. To have also a considerable electricity production (with photovoltaic), in order to balance the energy need of the building, solution D has to be chosen. Table 3: The table resumes the analysis performed with Radiance and ESP-r and shows the daylight-autonomy (DA), the solar control (SC), the Glare protection (GP), and the visual contact (VL) performances together with the electricity production (EP) of the six different façade designs.

DA SC GP VC EP

A -++ ++ ++

B o + ++ ++

C + o ++ --

D o + + + +

E + + + ++ o

F ++ + -

5. CONCLUSIONS The new angle selective pv-façade, proposed by the author, is a static shading device. It combines in one element four important tasks: solar protection (gvalue less than 10%), glare protection (DGP=0.22 for fully glazed external façade), visual contact (good visual transmission for view angle in the rage of − 35° ≤ φ ≤ 20° ) and integrated pv-system for electricity generation. These four elements, as are completely integrated in the function of the façade, do not reduce the architectural goal of the glazed façade and the view from the interior to the exterior is guaranteed. The system can be easily integrated in façade design as glazing façade, as window or as movable shading devices to protect the occupant from glare and to reduce the solar gains. RADIANCE and ESP-r simulations were done to assess the daylight and energy performances of the system if it is integrated in an office space façade.

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Six different façades design are assessed by the author, in order to give a first guideline on the optimum installation of the new system. The simulations reveal the good performances of the system especially for large office spaces or in fully glazed large-buildings (e.g. airport hall, tradefair,…).

6. REFERENCES [1] J. Clarke, Energy Simulation in Building Design, second ed., Butterworth-Heinemann, 2001. [2] EN410: Glass in building - Determination of luminous and solar characteristics of glazing, March 2000. [3] F. Frontini, S. Herkel, T.E. Kuhn, Validation of a new method for solar control calculation in the ESP-r building simulation programme, submitted for publication to Energy and Buildings. 2010 [4] F. Frontini, T. E. Kuhn, A new angle-selective, see-through bipv façade for solar control, Proc. Eurosun 2010, Graz, 2010 [5] F. Frontini, T.E. Kuhn, S. Herkel, P. Strachan, G. Kokogiannakis, Implementation of a new bidirectional solar modelling method for complex façades within the ESP-r building simulation program and its application, Proc. of the 11th International IBPSA Conference, 2009. Glasgow. [6] F. Frontini, T.E. Kuhn, Development of a new vertical angle-selective façade for solar control. 7° convegno nazionale ISTeA, Lerici 2008. [7] S. Kühn, Modellierung von Transparenten Wärmedämmaterialien auf der Basis spektraler Daten, Diplomarbeit, University of Freiburg, 1996. [8] G.W. Larson, R. Shakespeare, Rendering with Radiance: the art and science of lighting visualization, Morgan Kaufmann: San Francisco, 1998. [9] J. Wienold, Daylight Glare in Offices. Doctoral Thesis, University of Karlsruhe. 2009. [10] J. Wienold, J. Christoffersen, Evaluation methods and development of a new glare protection model for daylight environments with the use of CCD cameras, Energy and Buildings, 2008.

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A Method for integrating visual comfort criteria in daylighting design of school BEATRIZ PIDERIT1, MAGALI BODART2, TOMAS NORAMBUENA3 1

Departamento de Diseño y Teoría de la Arquitectura, Universidad del Bio-Bio, Concepción, Chile 2 Architecture et Climat, Université catholique de Louvain, Louvain-la-Neuve, Belgium 3 Molecular Genetics and Microbiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile. ABSTRACT: This paper presents the principles and methods for the integration of natural light and comfort criteria into architectural classroom design. The aim is to create the basis for incorporating these principles in the design of Chilean classrooms, to improve daylighting design in order to minimize glare and achieve more uniform daylighting levels throughout the school year. Firstly, the fundamental principles that directly affect design are defined. Secondly, the evaluation methods and measurements for those principles are described. Finally, we give some preliminary results for the various typologies and daylighting strategies. The research context is the city of Concepción, in Chile. Virtual models of classrooms were evaluated with the Radiance software. The annual assessment of the light performance of each classroom type was made for each of the four cardinal directions (north, south, east and west) and under the four sky types defined by CIE during the school year, March to December. The methods used and the formats for the representation of results are defined for each design principle. This paper proposes a new methodology, which could be implemented in future classroom design and also could be employed to evaluate existing classrooms. Keywords: daylighting, classrooms design, simulation, glare, visual comfort.

1. INTRODUCTION Natural lighting and external views have significant beneficial effects on human health and wellbeing as well as on the productivity of the building occupants [1]. Moreover, daylighting has the potential to improve student performance [2]. Some studies show that teachers and students can have clear preferences in classroom lighting [3] and that teachers prefer daylight. In Chile, the relationship between daylighting and wellbeing, and between visual comfort and performance, has not yet been explored. Building standards regulate daylighting in classrooms by specifying minimum window area to be 20% of room floor area. The minimum illuminance level required is 180 lux on the desk in “the least illuminated sector of the room” [4]. However, this value is very low in comparison to international levels. There is no design recommendation to guide architects and these standards fall far below those recommended by the standards set by the Illuminating Engineering Society of North America [5]. The objective of this paper is to create the principles, analysis methods and representation mechanisms for the study of natural illumination and visual comfort in classrooms, and to provide a basis for appropriate Chilean design standards. Four fundamental criteria are established, which should be integrated into architectural classroom design in order to guide architects in how to optimise natural light and avoid the risk of glare. These basic principles are listed below: 1. Providing the adequate amount of daylight in the classroom. 2. Achieving the adequate daylight uniformity in the classroom. 3. Ensuring visual comfort in the field of view of the students.

4. Preventing direct sunlight penetration in the classroom.

2. METHODOLOGY

The method used in this study can be divided into three parts: the calculation of illuminance, the evaluation of the risk of glare and the determination of sunlight penetration. These methods were applied in a preliminary study, which helped to define the method and to set the parameters for Radiance. The definition of these parameters was supported by a convergence study, which demonstrated that the accuracy of the data is proportional to the simulation time: the greater the accuracy of data obtained, the more will the Radiance simulation be delayed. 2.1. Illuminance Value The illuminance metric suggested in this study is based on Lightsolve illuminance metric [6], which presents the evolution of illuminance performance over the year. It was used to evaluate if the first two principles were achieved in the case studies. Three ranges are proposed: satisfying illuminance values („in range‟), too low illuminance values („too low‟), or too high illuminance values („too high‟). This method allows for the identification of satisfactory illuminance for multiple-purpose classrooms. IESNA recommends illuminance values for classrooms with a maximum between 150-2000 fc (1614-2150 lux) and a minimum between 30-70 fc (322-753 lux) [5]. These ranges were adapted according to the task performed in the classroom: „in range‟ illuminances between 500-1500 lux; „too low‟, < 300 lux; or „too high‟, > 2000 lux. The horizontal illuminance on the students‟ work plane was calculated with 15 sensors, distributed uniformly throughout the classroom, at a height of 70cm. Vertical illuminance was calculated on the blackboard surface to evaluate light distribution on it.

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We located five sensors at a height of 1.5m on the whiteboard surface (Fig. 1).

subjects rated the glare within their field of view to be imperceptible for DGP < 35%, perceptible for DGP between 35%-40%, disturbing for DGP between 40%-45% and intolerable for DGP > 45% [8]. 2.3. Sunlight Penetration For the fourth principle this work included a study of patches of sunlight on classroom surfaces. Fisheye view (quick rendering) images were created which showed the whole room, from above looking down (with the window at the top of each image), and the sunlight patch patterns from the windows to assess the moments in the year for which direct sunlight entered the classroom (Fig. 3). Sunlight�Penetration����������������������������������������������������������������������������������������������������������������������������������������������������������������������������Period�1 16h

16h

16h

Typology�g1

Typology�g2

Typology�g4

Typology�g5

Fig. 1: Horizontal and vertical grid.

2.2. Glare Metric The third principle suggests preventing sources of glare. The risk of glare was evaluated through the calculation of the Daylight Glare Probability (DGP)[7], which determines the percentage of persons disturbed by a daylighting glare source and was calculated using the evalglare command-line in Radiance. DGP values were validated in the range of 0.2-0.8, i.e., between 20% and 80% of disturbed persons. This index is vertical illuminance at eye level, luminance source, solid angle of source and glare position. For evaluating the discomfort glare in daylit classroom we chose the least favourable view of the preliminary study, where we studied four positions within the classroom as seen in the figure. The DGP was calculated for one direction: the horizontal view in the direction of the whiteboard and teacher area for a seated student (Fig. 2).

Fig. 2: Radiance rendering of view and classroom chosen, with four positions taken from the preliminary study.

In order to guide and simplify the understanding of the GDP index, we complement the glare risk study with DGP rating proposed by Wienold who organizes the DGP index in ranges in which human

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Typology�g3

Fig. 3: Fisheye view images of patches of sunlight corresponding to the five typologies, period 1(march 21) at 4pm for intermediate sky condition.

3. SIMULATION OF CLASSROOM DESIGN OPTIONS Five classroom design options, differing by their daylighting strategies, were modelled. Modelling was conducted for classrooms located in Concepción in the south of Chile at 36°46‟S, 73°3‟ W. For the design of these models, three common points are used: a) The classroom dimension was defined according 2 to national standards, with a floor area of 56m for 45 students, a typical 6 x 9m room, and a standard furniture arrangement was chosen as well (Fig. 4). b) We organize the main window into two windows, a view window to provide visual connection to the outdoors and a high sidelight window. c) The main window does not touch the wall of the whiteboard, leaving a distance of 1.50 meters The typologies differ by their second open façade (opposite to the main façade) as illustrated in Fig. 5. In order to compare and assess the four configurations according to the previously mentioned principles, Radiance simulations were done for each of the four main orientations: North, South, East and West, with the purpose of determining the favourable and unfavourable aspects of each orientation in search of the most optimal solution. 3.1. Time Segmentation The analysis was performed with Radiance for 20 time periods defined on the basis of the Chilean academic year, which starts in March and ends in December. Representative days and hours were fixed: the 21st March, the 21st June, the 21st

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

September and the 21st December, 8am, 10am, 12pm, 2pm and 4pm hours.

Fig. 4: Classroom dimensions and main façades

the intermediate sky [10], the clear sky and the clear turbid sky [11]. The TMY2 climate data provides average horizontal illuminance for these types of skies and the percentage probability in which each sky type occurs for each representative period: February to April, May to July, August to October and November to January (Fig. 6). The average sky conditions were obtained from the middle of the four periods considered. Using these average values and weights, we were able to create four realistic, instantaneous sky maps which still represent the entire period in question [12]. We calculated the average illuminance based on the equation from the ASRC-CIE model with the following formula: Ei = pc Ei,c + pct Ei,ct + pi Ei,i + po Ei,o , where Ei is the illuminance at the sensor and Ei,c, Ei,ct, Ei,i and Ei,o are the illuminance values at the sensor under the four defined skies. The weighting factors pc, pct, pi and po were obtained from the weather data and represent the frequency of each sky type over the considered period, according to a methodology similar to that developed by Andersen et al [13]. The risk of glare was evaluated through an average DGP in the same way, using the average value and weights. Finally, we made two graphs for the DGP index: one for the predominant sky and the other for the most glaring sky.

Fig. 6: TMY2 weather-based graph, period 1 (February to April), period 2 (May to July), period 3 (August to October), period 4 (November to January) skies frequency.

4. DAYLIGHTING ANALYSIS PRESENTATION OF RESULTS

AND

The next stage of this study was to generate a database of daylighting results. The preliminary results and conclusions of the analysis carried out are presented in graph form. Results are separated into temporal information that corresponds to the annual information on the weighted values and supplementary information with detailed information for 20 moments of the year. 4.1. Temporal Information Fig. 5: Sectional cuts showing five different classroom designs.

3.2. Sky Conditions For the definition of sky conditions for each period, we considered weather data on the basis of the TMY2 weather data file and the four standard skies of the ASRC-CIE model [9]: the overcast sky,

Illuminance and glare information are displayed in temporal maps, annually [14]. The temporal maps were produced in MATLAB in order to show, in a single graph, the periods of the year in which the design objectives were achieved, represented in the following way: x-axis for date, y-axis for time of day (fig 6). For illuminance temporal maps we used

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triangular scale proposed in “Lightsolve” in order to easily interpret the range of values obtained in the maps (Fig. 7). This scale summarises the percentage of daylighting that annually falls either in range, too high or too low.





4.1.1. Temporal Illuminance Maps The Temporal Illuminance maps were drawn according to goal values (goal oriented approach) and represent the percentage of the task area fulfilling these goals. The values shown are the percentage that achieved the range defined between the minimum required illuminance of 500 lux (with partial credits up to 300 lux) and the maximum acceptable illuminance of 1500 lux (with partial credits up to 2000 lux).



“irregular spatial distribution”, is defined as irregular if there is less than 50% of the space whose values are “in range” throughout the year. “regular spatial distribution”, is defined as regular if it is between 50% and 75 % of the space whose values are “in range” throughout the year. “optimal spatial distribution”. The distribution of daylighting is defined as optimal if there is more than 75% of the space whose values are “in range” throughout the year.

4.1.3. Temporal DGP Maps Two temporal DGP maps are presented: the first has the DGP for the whole year weighted according to weather and the second is maximum DGP for the whole year when considering only skies which induce the strongest glare (Fig. 8). The best way to analyse the temporal maps is to compare the different configurations tested.

Fig. 7: Temporal maps’ distribution and triangular scale.

4.1.2. Spatial Illuminance Distribution maps In order to understand the distribution of illuminance in the classroom, we showed illuminance distribution in different areas of the classroom, allowing for an easy identification of areas within the classroom that meet target illuminance values or, in the same way, knowing which areas have too much or too little daylight. This map is represented in the following way: xaxis and y-axis are the meters, the size of the classroom. The illuminance distribution is related to the horizontal grid (Fig. 1).

Fig. 8: Temporal DGP and DGP max Maps of North-facing Typology g1.

4.2. Supplementary Information It is essential to present the global illuminance and the average horizontal illuminance inside the classroom for the four periods analysed for each simulated sky in order to know both the available global illuminance and the average illuminance within each classroom configuration during a specific period of the year for each sky type: overcast („o‟), clear („c‟), intermediate („i‟), and clear turbid („ct‟), (Fig. 9).

Figure 7: Spatial maps distribution with triangular scale for North-facing Typology g1.

Along with the development of spatial graphs, we determined the percentage of space over the year whose values are in range, too low and too high. The three levels are defined to describe the distribution and they are described below:

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Fig. 9: Graph for Global illuminance (outside), average internal illuminance values. Below: Illuminance for the predominant sky.

In order to study the daylight distribution in classrooms types, both on the horizontal plane (Fig. 9) and on the whiteboard surface (Fig. 10), the

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

illuminance obtained with the predominant sky type of each period was shown, with an initial graph that displayed the minimum and maximum values and average values, also observing the obtained uniformity. Subsequently, the internal light distribution could be determined for each moment of the day, hour by hour.

being typology 3 the most unfavourable with a 44% average “too high” illuminance value. In contrast, nearly all South-facing typologies achieve values above range 50% of the time, with the exception of typology g2. In case of the East-facing classrooms, all the typologies have problems in the morning with sunlight penetration. For this reason, none achieves the design goal. In the case of West-facing classroom results, four typologies (g1, g3, g4, g5) nearly reach the objective of the design, but it is necessary to optimize the design by adding some afternoon sunlight protection. Table 1: Summary of average range value results for horizontal temporal illuminance maps.

Fig. 10: Graph from the preliminary database of the illuminance on the whiteboard.

The DGP study was complemented by a graph illustrating two represented values: first, the DGP values for the predominant sky and, secondly, the DGP values for the most glaring sky at each of the dates and hours studied (Fig. 12). These graphs are then used in order to qualify glare perception as per the adjectives proposed by Reinhart and Wienold [15].

Fig. 11: Images displayed in database.

To complement glare information, 20 views are created for each classroom configuration. These views represent the whole year (represented by 20 moments) and the predominant sky at each moment. The views are represented in false-colour image with a scale of luminance between 0 and 2000 cd/m². Also, we show the glare source image and the human sight(Fig. 11) in order to help the understanding of where is the glare source.

The results of vertical illuminance on the whiteboard, for the South-facing classroom temporal maps, show that all the typologies achieve a good illuminance level, in range > 60 % of the year. Northfacing typologies g1 and g5 achieve the design goal while the others have problems of sunlight penetration in the whiteboard area. Table 2: Summary of Spatial Illuminance distribution maps, percentage of space over the year whose values are in range, too low and too high

Fig. 12: Example of DGP rating graph.

5. RESULTS With regard to light distribution in the classroom, the design objective is to ensure illuminance levels within the proposed range over 50% of the time. Table 1 summarises the temporal map results for annual horizontal illuminance, where we can see that no North-facing typologies fulfil this design objective,

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The spatial illuminance results illustrated in Table 1 show the average values for each typology and the qualification of classroom distribution illuminance weight. We find for North, East and West-facing class illuminances "too high" next to the window. They have critical periods from March to April and from August to October. Only typology g2 achieves a regular distribution for all orientations. Finally, the glare risk analyses with DGP index results indicate that all _North-facing classrooms‟ DGP and DGPmax are within the intolerable range. The East and West-facing classrooms have a DGPmax also within an intolerable range. Most of the South-facing typologies have no sources of glare, with the exception of typology g2.

6. CONCLUSION AND DISCUSSION In conclusion, the research findings of this study have provided some evidence that there is a relation between the horizontal illuminance temporal maps and the spatial temporal maps. If the average "in range" is more than 55%, the result would be an "optimal” spatial distribution of weighted illuminances. It would be useful to optimise the architectural design of those typologies that do not achieve an optimal distribution, particularly of those classrooms that have very high illuminance, in order to try to achieve the proposed design range and optimal distribution. The next step of this work is to generate a database that enables architects and designers to read the results clearly and easily, and to use it as a design tool. While the architectural possibilities are endless, we believe it is possible to advise architects in order to foresee and avoid potential problems that some classroom configurations might cause. The results of this study should be replicated for other classrooms or for other cities in Chile or other countries that could, hence, expand the database.

7. ACKNOWLEDGEMENTS The authors would like to thank the Bioinformatics Laboratory of the Catholic University of Chile, in particular to Dr Francisco Melo for his support in conducting the large number of Radiance simulations.

8. REFERENCE [1] Boyce, P. R., 2003, Human factors in Lighting. Troy: Lighting Research Center, 2nd Edition. [2] Heschong Mahone Group. 1999. Daylighting in Schools: An Investigation Into Relationship Between Daylighting and Human Performance; Detailed Report, Pacific Gas and Electric Company. [3] Schneider, M.,2003. Linking school facility conditions to teacher satisfaction and success. Washington, DC: National Clearinghouse for Educational Facilities.

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[4] Ordenanza General de Urbanismo y Construcciones. Titulo 4: Cap.5, Articulo 4.5.5. “Locales escolares y hogares”, Chile. [5] Rea, M. 2000. The IESNA Lighting Handbook. published by the Illuminating Engineering Society of North America. ISBN 0-87995-150-8 (New York, NY: IESNA). [6] Cauwerts C., Bodart M., Andersen M. 2009. A first Application of the Lightsolve Approach: Predesign of the new Belgian VELUX headquarters. Proc. 26th International conference on Passive and Low Energy Architecture (PLEA) : 373-378. [7] Wienold J., Christoffersen J., 2006. Evaluation methods and development of a new glare prediction model for daylight environments with the use of CCD camera. Energy and Buildings, 38(7): p.743-757 [8] Wienold, J., 2009, "Dynamic Daylight Glare Evaluation", Proc. of Building Simulation 2009, Glasgow (UK). [9] [CIE] Commission Internationale de l‟Eclairage. 1994. Spatial distribution of daylight –luminance distributions of various reference skies. Vienna (Austria). CIE. Publication No110–1994. [10] Perez R, Michalsky J, Seals R., 1992, Modeling sky luminance angular distribution for real sky conditions: experimental evaluation of existing algorithms. J ILLUM ENG SOC., 21, 84-92. [11] Igawa N, Nakamura H., 2001, All Sky Model as a standard sky for the simulation of daylit environment. Building and Environment 36(6): 763–770. [12] Kleindienst S., Bodart M., Andersen M., 2008, Graphical Representation of Climate-Based Daylight Performance to Support Architectural Design. Leukos, 5, 39-61. [13] Andersen M., Kleindienst S., Yi L., Bodart M. and Cuttler B., 2008. An intuitive daylighting performance analysis and optimization approach. Building Research and Information, 36(6): p 593-607 [14] Mardaljevic J., 2004, Spatio-temporal dynamics of solar shading for a parametrically defined roof system. Energy and Building 36(8): p. 815-823. [15] Reinhart C. and Wienold J., 2011, The daylighting dashboard - A Simulation-based design analysis for daylit spaces, Building and Environment 46 (2): p.386-396.

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A Novel Louver System for Increasing Daylight Usage in Buildings Kevin THUOT1, Marilyne ANDERSEN2 1

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ABSTRACT: Advanced daylighting systems can be effective in increasing light levels in building spaces and reducing energy consumption due to electric lighting. However, a recurring issue found in most existing daylighting systems is the necessity of coupling the light-redirecting technology with a separate light shade to reduce glare risks. A different approach is proposed here, based on the use of a louver system which scatters incoming light onto a reflective ceiling, where it is redirected deep into the space. This type of system is effective for both diffuse daylight and direct sunlight without causing glare and without the need for a shading system. Annual simulations of workplane illuminance were conducted with Radiance using Tokyo weather data and a generic south-facing deep-plan office space. Glare was evaluated through testing of a physical prototype of the system. The new system was compared to a base case consisting of an unshaded window of equal area to the louver system. The results show that the novel louver system enables a significant decrease in electric lighting usage and outperforms the uncovered window, while adequately controlling direct sunlight to prevent glare. Keywords: daylighting, louver, anidolic, building technology

1. INTRODUCTION This paper introduces the design and operation of a new type of daylighting system. Daylighting systems are used to provide natural light to building spaces, reducing the need for electric lighting. Effective use of daylight has several positive benefits including lower energy bills, lower fossil fuel consumption for electricity generation, and increased work environment satisfaction for occupants [1]. The intention of this paper is to provide a proofof-concept for the new daylighting system. The system described here is best suited for buildings with deep open-plan spaces, commonly found in office buildings. Both direct sunlight and diffuse skylight are directed into the room at an angle near horizontal, which allows the light to penetrate deeply. The system is designed to laterally diffuse incoming light in order to minimize glare resulting from direct sunlight. In this paper, the nature of the design problem is discussed and a description of the system is given. Test results from computer simulations, as well as a physical prototype, are also provided.

2. CONTEXT OF DESIGN In general, daylighting systems can be divided into two categories: passive and active. Passive systems are fixed and contain no moving parts. Active systems contain moving parts, which are usually used to track the sun as it moves across the sky. Since they have no moving parts, passive systems are generally less expensive and require less maintenance than active systems. However, these passive systems are typically only effective for a limited range of sun and sky conditions and some allow direct sun to pass through unimpeded at times, potentially causing glare. As a result, a separate

shading system is often required, which leads to additional problems resulting from suboptimal control of the shading system [2]. Active systems are typically used to respond to the active nature of the sun. A common example is the venetian blind, whose slats can be adjusted, manually or automatically, in response to different insolation conditions. When automated, these systems are typically more expensive in both upfront and maintenance costs than their passive counterparts because they require rotating machinery, an accurate control system, and human monitoring [1]. Another limitation is that since most active systems are designed to use the sun‟s radiation as input, their effectiveness is severely reduced under overcast conditions. In cloudy climates it may be difficult to justify the additional expense of a sun-tracking active system.

3. EXISTING SOLUTIONS In broad terms, the goal of this design effort is to develop a passive system that performs well under all sky conditions, without causing glare. Two existing groups of technologies that informed the design of the new system were anidolic and louver daylighting systems. 3.1. Anidolic Systems The search for a passive system that could redirect light deeply into a room, while also preventing direct sunlight from entering at a downwards angle, led to the science of non-imaging optics and a technology called the Compound Parabolic Collector (CPC). The field of non-imaging, or anidolic, optics was initially used in the development of solar energy collectors. The CPC was first used as a solar concentrator that could accept all light rays from a defined angular extent

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and concentrate them on a smaller area. The CPC, when used for daylighting applications, uses the same type of reflector profile, but light moves through it in the opposite direction. Light enters from all directions through a small inlet aperture and is aligned into a controlled angular range at the outlet [3]. Existing anidolic systems, based on the CPC, were found to have several major shortcomings when applied to an office building setting. First, for the system to be effective, it had to be excessively large, on the order of 1 to 2 m long and .5 to 1 m tall. This size reduces the ceiling height, makes using the space near the façade awkward, and complicates the construction of the façade. Second, when exposed to direct sun, the anidolic system is excessively bright and requires shading. In an open-plan office, blinds that are shut to control glare often remain shut for long periods of time [2]. This problem is only fully overcome by automating the shading system to eliminate the need for adjustments by the occupants. 3.2. Louver Systems Reflective louvers form a second relevant group of daylighting systems. The main advantage of a louver system over a full-size anidolic system is that the louver systems are easier to integrate into a building and maintain because they are much less bulky and can be located between the panes of a double glazing. Examples of existing louver systems include the Fish System and the LightLouver [1, 4]. These systems generally consist of a vertical array of identically-shaped curved slats, whose profile is defined so that daylight is redirected up onto the ceiling [1]. These existing systems, while useful, suffer from several drawbacks. For particular times of the day and year they can emit daylight at too high of an angle to allow the light to penetrate deeply, or worse, they can allow light to exit at a downward angle, potentially causing glare under direct sunlight. A second issue is the amount of light rejected by the outer part of the louver. When designed as passive systems, louvers often have difficulty admitting a wide range of incoming light directions while also effectively controlling the light output. Another drawback of these existing louver systems is that, although they may emit light at an angle near horizontal, light penetration depth is limited because they are designed to direct light onto a diffusing ceiling which scatters light uniformly in all directions.

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the system to minimize maintenance and space usage.  Effectiveness: The system must respond well to both overcast and sunny conditions throughout the day and year.  Visual Comfort: The system must avoid causing glary conditions inside the building space for all sky conditions.  Passive Operation: The system should not require either human or computer-based adjustments to operate effectively.  System Size: Real estate is usually very precious (and particularly expensive in Tokyo, the case study location), so the system size must be limited and must not interfere with the normal use of the office space, or the ability to see outside. The vertical extent of the proposed system is limited to the top .7 m of the façade. This distance includes .1 m for a horizontal mullion at the bottom of the daylighting unit, leaving .6 m of vertical height for the system itself.  Ceiling Height: The floor to ceiling height is fixed at 2.8 m. A higher ceiling would improve lighting performance but maximizing rentable area takes precedence.  Office Space: The space to be daylit is very deep at 12 m. The space is sidelit only.  Urban Surroundings: Tokyo's urban landscape is full of tall, densely packed buildings. The result is obstructed sky views, especially the lower portions of the sky.

5. SYSTEM DESCRIPTION A key insight gained during the review process of existing systems was that the principles of the CPC could be used to create a new louver system, which would improve on or eliminate the drawbacks of both the anidolic and louver systems described in Section 3. The resulting design is an original louver system that incorporates a CPC profile. The louvers, when combined with two other system elements, form an effective daylighting system which meets all of the requirements laid out in Section 4. The system is comprised of two major subassemblies. The first of these subassemblies is a window unit installed at the top of the daylit façade. The other subassembly consists of reflective panels which cover the ceiling from the daylit façade to a distance of 6 m inboard (distance varies based on room size).

4. PERFORMANCE OBJECTIVES

5.1. Window Unit

For the daylighting system to function effectively in a real office building setting, it will be subject to design constraints (visual comfort, space usage, etc.). As a result, a set of relevant reference performance objectives were developed based on the needs of the project sponsor, a commercial real estate development company located in Tokyo, Japan. Below are the key reference design requirements. The requirements reflect the desire for

Figure 1 shows views of the window unit‟s crosssection. The unit contains two glass panes, similar to a standard double glazed window unit. Two different optical devices are located between the outer and inner glass panes. Both of these devices are sensitive to dust and scratching, so placing them inside the window unit provides protection and eliminates maintenance.

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range, the more low angle light will be rejected at the inlet. For an urban setting such as Tokyo, the impact of losing light from near the horizon is less significant than it otherwise would be because the urban surroundings will often block the view to the bottom portion of the sky. All light that impinges on the louvers at an angle of 27° or greater will pass through the louver array successfully (minus absorption losses). 5.3. Refractive Rods

Figure 1: Window Unit Side View (Left) and Top View (Right)

The system is designed so as to ensure incoming light is redirected and diffused when entering the space so as to avoid glare risks. As a consequence, there is no view through the window unit itself, and the bottom of the unit should be no lower than approximately 2.1 m off the ground to allow for a view window on the rest of the façade. 5.2. Louver Assembly The core of the system is a vertical array of reflective louvers which redirects incoming light in a controlled manner deep into the space. Figure 2 shows the relative positions of two louvers in the vertical array. The absolute size of the louver crosssection can be increased or decreased, but the ratio of the dimensions must remain the same for the device to function properly. The louvers have a constant cross-section in the direction normal to the page. The output range for light emitted from the louvers is between 0° and 40° above horizontal, regardless of the incoming direction of the light. Figure 2 also shows how incoming rays at different positions and elevation angles will be redirected by the louvers. Notice that of all the ray paths traced in the image, none exits the louver channel at an angle less than 0° above horizontal.

The louvers change the elevation of the incoming light but they do not significantly alter the light‟s azimuth angle. Without the inclusion of the refractive rods, under direct sun, the reflective ceiling will exhibit a bright streak located on a line between the occupant‟s eyes and the sun, similar in appearance to the sun‟s reflection off a moving body of water. During mock-up testing (discussed in Section 7) a 2 maximum brightness of about 350,000 candelas/m (or .02% of the luminance of the sun at mid-day) was observed on the ceiling when using the louvers without the refractive rods and this level of luminance was deemed to be too high for an office environment. To mitigate glare concerns, a horizontal array of optically clear rods, made of either acrylic or glass, placed at the outlet of the louvers has the effect of spreading the incoming light in the azimuth direction, without affecting the light‟s elevation angle. Under direct sunlight conditions, the bright streak on the ceiling is replaced with a much larger area of lower brightness (see Figure 9). Diffusing direct sunlight in this manner helps prevent glare from being an issue. The total amount of light in the room is modestly reduced by adding the rods, but the glare protection they provide justifies their inclusion in the design. Figure 3 provides an illustration of how the rods affect light passing through them.

Figure 3: Ray Tracing through Transparent Rods Illustrating Their Ability to Mitigate Glare Resulting from Collimated Sunlight

5.4. Reflective Ceiling

Figure 2: Ray Tracing through Louvers for Varying Incoming Elevation Angles

One important limitation to note is that some low angle light is rejected by the louvers. The cut off elevation angle, where the majority of incoming light rays are rejected, varies between 27° (for light normal to the façade in azimuth) to 0° (for light nearly parallel to the façade in azimuth). With this type of louver design, the tighter the output light's angular

The final element of the proposed daylighting system is the reflective ceiling. The purpose of the reflective ceiling is to redirect light emitted by the window unit deeper into the space. To limit glare and distracting mirrored reflections on the ceiling, the reflective surface has bumpy texture, which helps to scatter the light without eliminating its directionality. If the surface of the ceiling had a typical matte or diffuse finish then most of the light exiting the window unit would hit the ceiling near the front of the room and be scattered onto the workplane immediately below. With a diffuse surface, impinging light is scattered in all directions evenly so only a small

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6. SIMULATION RESULTS 6.1. Model Description To give a quantitative idea of how the system performs, the figures in Section 6.2 show illuminance results for a generic south-facing building space with the full daylighting system compared to the same space with an unshaded window and a diffuse white ceiling for two different representative sky conditions. The unshaded window is a common point of comparison for daylighting systems under test and is one of two standard reference cases defined by the International Energy Agency‟s Solar Heating and Cooling Task 21 [1]. A generic unshaded window provides a simple reference case that is easily modelled and understood. The lighting simulation program Radiance was used to run the simulations [5]. To conduct annual simulations in a reasonable amount of time, the daylight coefficient method employing the rtcontrib Radiance program was utilized [6]. The façade below 2.2 m from the floor is modelled as an opaque wall for both cases to isolate the effects of the daylighting system. The base case leaves the top .6 m of the glazed façade uncovered, while the system case includes the full daylighting system. The building space is located using Tokyo‟s latitude and longitude and its south façade has an unobstructed view of the sky. Workplane illuminance

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values are measured along the centerline of the room moving away from the south façade. All walls, other than the top of the south façade, are completely opaque. The Tokyo weather file available from the Energy Plus website was used as the source for direct normal and diffuse horizontal irradiance values. Additional model details are provided in Figure 4 and Table 1.

Figure 4: Plan (Top) and Section (Bottom) Views of Model Space with Dimensions Table 1: Radiance Model Parameters Floor Reflectance Wall Reflectance Standard Ceiling Reflectance / Specularity Reflective Ceiling Reflectance / Specularity Louver Reflectance Rod Transmittance / Index of Refraction Window Transmittance (for Double Pane)

0.20 0.60 0.80 / 0.00 0.88 / 0.95 0.92 0.92 / 1.50 0.74

6.2. System Performance Under sunny conditions, the louver system outperforms the unshaded window base case, as shown in Figure 5. The louver system provides significantly more light than the base case for depths of 2.5 m or greater. Also, the louver system avoids the extremely high peak illuminance seen in the base case resulting from direct sunlight transmission. In practice, the illuminance peak from direct sun would likely cause the occupants to partially or fully close the blinds, reducing the room illuminance contribution from daylight. For reference, the minimum recommended illumination level for office work is typically between 300 and 700 lux. 4000

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portion would be reflected off the ceiling deeply into the space. This is true even of light that exits the louvers near horizontal. A diffuse ceiling wastes much of the benefit of the louvers, because the ceiling cannot take advantage of the fact that the light impinges on it at a shallow angle. Since increasing the distance from the louvers to the ceiling is not an option due to economic constraints, another solution to push light deeper was sought. Using a ceiling with a specular, rather than a diffuse, surface makes the overall system much more effective. Light hitting the ceiling at a shallow angle bounces off at a shallow angle. This means that all the light is directed deeper into the space at a favorable angle, rather than being diffusely scattered. The refractive rods and bumpy ceiling texture prevent the specular reflection off the ceiling from causing glare by reducing the peak brightness associated with direct sunlight. This method of diffusing incoming light should provide protection from thermal discomfort as well, since the building occupants are not exposed to direct sunlight. With regard to solar gains, this system will allow a heat input similar to the standard glazed curtain wall with interior blinds. Its overall impact on building loads will also be limited since the daylighting window unit only covers a fourth of the full façade height. For a daylit zone extending 12 m from the façade, the recommended length for the reflective ceiling is 6 m, but this could be reduced to 4 m with a relatively small impact on performance if cost or other considerations limit the allowable length. The rest of the ceiling beyond the end of the reflective section could use a standard acoustical tile layout.

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Figure 5: Sunny Case: March 24, 11:30am (Direct Normal Irradiance: 955 W/ m2, Diffuse Horizontal Irradiance: 97 W/ m2) *Base Case at 1.5 m is 20,413 lux

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Under totally overcast conditions, the overall illuminance levels for both cases are much lower than for sunny conditions. Despite the reduction in absolute illuminance, the proposed louver system still outperforms the uncovered window at distances of 4.5 m or greater from the façade, as shown in Figure 6. The system also increases the uniformity of light levels in the room. System Base Case

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Figure 6: Overcast Case: March 25, 11:30am (Direct Normal Irradiance: 1 W/ m2, Diffuse Horizontal Irradiance: 260 W/ m2)

For situations where there is significant sky obstruction near the horizon due to the daylit building‟s surroundings, the louver system performs even better relative to the uncovered window case. This is because the uncovered window relies primarily on light from near the horizon to illuminate the deep parts of the space, unlike the louver system. Also, for the open window case to be a viable option it would require some type of movable shading system to shield the office space from direct sunlight, a drawback the louver system does not suffer from. To give a more complete impression of the system‟s performance on an annual basis, Figure 7 provides the median annual workplane illuminance values for selected hours of the workday. The louver system consistently provides more light than the base case at distances greater than 3.5 m from the façade.

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Figure 8: Percent of Working Hours (8am-7pm) with Workplane Illuminance Greater than 300 Lux

In addition to outperforming the uncovered window base case, the new system appears to also outperform many existing passive daylighting systems. Aizlewood conducted a study of four different advanced passive daylighting systems: a light shelf, Okasolar louvers, a prismatic glazing, and a prismatic film [7]. All of these systems were found to reduce workplane illuminance compared to an unshaded window for overcast conditions. Under the variety of sunny conditions found over the course of the day and year, no system was able to consistently provide increased workplane illumination in the rear part of the room either. Furthermore, it was determined that all of the tested systems, other than the prismatic film, required a separate shading system in order to limit glare. Although these results suggest that the new system may provide superior performance in terms of amount of illumination, depth of illumination, and glare control, making a conclusive judgement of the relative effects of two different daylighting systems requires that both be tested under identical conditions.

7. PHYSICAL PROTOTYPE A physical prototype of the daylighting system was built to test for glare problems as well as to obtain a qualitative understanding of aesthetics of the system. The dimensions of the completed louver unit were .27 m wide and .15 m tall, not including the frame. The prototype used eight louvers, whereas the real system would use approximately 30 to fill the .6 m facade height allowed. Glare was evaluated using point luminance readings as well as qualitative assessments and was not found to be a significant concern. At its brightest, the reflective ceiling does not cause visual discomfort, provided the ceiling is not in the center of the field of view. The ceiling can cause slight visual discomfort if in the center of the field of view. These conclusions will be refined with additional testing. The addition of the refractive rods to the system reduces the peak luminance of the ceiling while increasing the ceiling„s average luminance, as shown in Figure 9. The data presented in Figure 9 was

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recorded on a clear November day in Cambridge, Massachusetts near 10:45am at a constant distance of 3.5 m from the window unit. The prototype was aligned so that the azimuth angle of the incoming direct sunlight was 90°.

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8. CONCLUSION The new daylighting system proposed here has the potential to bridge the gap between automated systems that are expensive and maintenanceintensive and passive systems which are often ineffective and cause glare. The system is simple, passive, and maintenance free. It is also well suited for both sunny and cloudy conditions without requiring any reconfiguration. The feasibility and performance of the system has been evaluated through the use of computer simulations and a physical prototype. The results are very encouraging, for both illuminance levels and visual comfort. Development of this technology is continuing and the completed system is planned to be permanently installed in a new Tokyo office building in 2012.

9. ACKNOWLEDGEMENTS With Rods Without Rods Figure 9: Prototype Ceiling Maximum Luminance (cd/m2) as a Function of Azimuth Angle to Façade

Figure 10 illustrates how adding the refractive rods reduces the peak luminance of the ceiling.

Figure 10: Peak Brightness of Prototype Under Direct Sun Without Rods (Left) and With Rods (Right)

Figure 11 shows a picture of a full scale mockup tested in Tokyo, Japan. Analysis of data from this more sophisticated mockup is in progress, but the results are well aligned with those of the initial mockup.

Figure 11: Full Scale Mockup Installed in Office Building Setting

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The authors would like to thank Hulic Co. Ltd., the Massachusetts Institute of Technology, and École Polytechnique Fédérale de Lausanne for their generous support of this research. Special thanks to Masashi Fukuda of Hulic and Dr. Leon Glicksman of MIT for their valuable input and collaboration. Thanks also to Lambda Research Corporation for supplying an educational TracePro licence.

10. REFERENCES [1] Ruck, Nancy C., et al. Daylight in Buildings: A Source Book on Daylighting Systems and Components. Washington, D.C.: International Energy Agency, 2000. Print. [2] Reinhart, C., and K. Voss. "Monitoring Manual Control of Electric Lighting and Blinds." Lighting Research and Technology 35.3 (2003): 243-60. Print. [3] Scartezzini, Jean-Louis, and Gilles Courret. "Anidolic Daylighting Systems." Solar Energy 73.2 (2002): 123-35. El Sevier Science. Web. 11 Aug. 2010. [4] Rogers, Zach L., Michael J. Holtz, Caroline M. Clevenger, and Neall E. Digert. Mini-Optical Light Shelf Daylighting System. Architectural Energy Corporation, assignee. Patent 6714352. 30 Mar. 2004. Print. [5] Larson, Greg Ward, and Rob Shakespeare. Rendering with Radiance: The Art and Science of Lighting Visualization. San Francisco: Morgan Kaufmann, 1998. Print. [6] Jacobs, Axel. "Understanding Rtcontrib (Version 5)." Luminance.londonmet.ac.uk. London Metropolitan University, 1 Feb. 2010. Web. 25 Feb. 2010. [7] Aizlewood, M.E. “Innovative Daylighting Systems: An Experimental Evaluation.” Lighting Research and Technology (1993): 141-152.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBN th xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The evaluation of solar energy potential and energy needs for heating and lighting using LIDAR data Applications on two real built up-areas Virginia GORI1, Carla BALOCCO1, Claudio CARNEIRO2, Gilles DESTHIEUX3, Eugenio MORELLO4 1

Départment of Energy Engineering "Sergio Stecco", Universtà di Firenze, Florence, Italy Geographical Information Systems Laboratory, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Swilzerland 3 Haute Ecole du Paysage, d'Ingénierie et d'Architecture, University of Applied Sciences Western Swilzerland, Genève, Switzerland 4 Laboratorio di Simulazione Urbana, Politecnico di Milano, Milan, Italy 2

ABSTRACT: A tool that estimates heating and lighting demand at the district level and at the same time computes the potential energy supply through solar and PV panels is proposed. The aim of this study is to provide useful guidelines to urban designers and policy makers in order to promote integrated energy strategies to be tailored according to the specific urban form. The tool is based on the use of digital 3-D data of cities derived from laser scanning to automatically compute energy needs at the district level. By focussing on urban geometry implications, such as shadowing conditions and leaning effect, we propose a method that allows calculating energy needs, available and useful solar energy of a group of buildings together. In particular, heating demand is calculated according to the current European Regulations, whereas for lighting demand a simplified method based on the Daylight Autonomy concept is suggested. Finally, solar irradiation is computed on all roof points and the potential of solar energy uses and applications is derived. The tool was validated by two case-study areas applications characterised by different building typologies: the centre of Florence (Italy) and the CERN campus in Geneva (France - Switzerland). Keywords: 3D data analysis, LiDAR data, 2.5-D urban surface models, digital image processing, renewable energy potential

1. INTRODUCTION The rational use of energy resources is the only way to reduce the environmental impact of human activities. Cities are thermodynamic systems that must be organized by relating variable energy demand to minimize entropy production. The aim of this work is to provide a tool that estimates the heating and lighting energy needs at the district level and at the same time computes the potential energy supply through solar and PV panels. Numerous and sophisticated tools that investigate and simulate the energy needs at the building level are available, but tools that inform decision makers at the urban scale are still lacking. In particular, the goals of this study are the following: To provide useful information and guidelines to urban designers and policy makers in order to promote integrated energy strategies to be tailored according to the specific urban form. In fact, depending on the availability and arrangement of urban surfaces, different solutions can be proposed. For example, incentives for the installation of PV panels can be provided on a very fine-grained basis, i.e. only where these are really effective. To set up an innovative tool to investigate energy problems at the scale of the neighbourhood and not of the building. We propose a new method that can use different

data sources and different data bases for evaluating energy needs at the urban scale, without complex and time consuming calculations. To provide a simple tool that considers a set of relevant variables at the urban scale: overshadowing by buildings, leaning effect (buildings touching each other’s thus reducing thermal dispersant surfaces). To make use of Laser Imaging Detection and Ranging (LiDAR) data which is an increasingly available and not so expensive source of information. The use of this type of data allows automatically reconstructing accurate 3-D city models with a Level of Detail (LOD) that includes superstructures, small objects and vegetation and, consequently, a synchronic picture of the urban environment (no time delays among the represented objects). The method applied in order to develop the tool is based on the use of digital 3-D data of cities derived from laser scanning and Digital Image Processing (DIP) techniques to automatically derive energy needs at the district level. By focussing on urban geometry implications, such as shadowing conditions and leaning effect, this innovative approach allows calculating a group of buildings together in a fast and accurate way. Our method is applied, on purpose, to two different urban areas respectively located in the centre of Florence (Italy) and the CERN campus

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

(France - Switzerland). In fact, these two sites differ in terms of spatial arrangements and configurations of buildings, typologies and materials of construction. In addition, the climatic data of the two locations are very different in terms of latitude, solar radiation, external air temperature and humidity and wind velocity and direction.

2. APPLICATION Numerous tools implemented at the building scale are based on expensive and dynamic calculations. This level of detail is not needed at the urban scale. In order to give back an overall idea of energy consumptions at the urban scale, a simplified tool is desirable. The method is based on the integration of several and different sectors and competences that include urban design and morphology, geography, energetic of urban systems, programming and image processing. In fact, the method is organized in a series of steps that cover those different technical competences (figure 1): 1. 2.5 Digital Urban Surface Models (DUSMs) reconstruction (mask construction); 2. The energy analysis of built up-areas based on the use of DIP techniques implemented on the Matlab ® environment; 3. Visualisation of results through maps; 4. Construction of energy scenarios for heating lighting and solar energy generation. ENERGY ASSUMPTIONS LiDAR DATA

2

1

URBAN MODEL CONSTRUCTION FROM RAW LiDAR DATA

2.5-DUSM GENERATION (DTM + nDSM of buildings)

PRODUCTION OF MASKS: 2.5 DUSM BUILDINGS BUILDING IDs ORIENTATIONS SLOPES

ENVIRONMENTAL DATA

ENERGY ANALYSIS THROUGH DIGITAL IMAGE PROCESSING OF URBAN MODELS

3 NUMERICAL OUTPUTS

4

A HEATING B LIGHTING C SOLAR IRRADIATION

CONSTRUCTION OF ENERGY SCENARIOS

NUMERICAL OUTPUTS

NUMERICAL OUTPUTS

HEAT MAPS VISUALIZATION OF RESULTS 2-D 2.5-D 3-D

Figure 1: The structure of the overall proposed method

In order to run our simulations, important information about buildings included in the two case study areas is inferred by two different databases respectively. For Florence a structured GIS database provides basic data on buildings belonging to a XIX century development of a part of the city. This database, that has been built up for the Municipality Environmental Energy Programming (PEAC), allowed to obtain thermo-physical parameters of the buildings and consequently thermal maps and energy savings scenarios basic for the whole urban area of Florence. It was built on building energy need evaluations on GIS using spatial analysis techniques to connect descriptive data of different plant typologies to the relevant buildings. A statistical method was used to evaluate the energy needs of the urban building system. The method utilises a numerical map to extend to the universe the evaluation obtained from a probability stratified

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simple random sampling design with the optimum allocation of sample buildings to the strata. The strata considered refer to the age of construction of buildings. This statistical approach to the energy analysis of the urban system required the primary definition of the energy characteristics of the universe of buildings. This was necessary to avoid systematic error in the calculation method of sample size and techniques to select the elements of sample units. An equal probability selection method (epsemdesign) of stratification by age classes was used, referring to existing information and data, cartography and historical series maps. Disproportionate stratification utilization was due to allocating sufficient sample size to certain strata, identified with the age classes of construction of buildings, in order to identify estimates of sufficient precision. Under these conditions sample estimates are required not only for the total population but also for various subpopulations which are termed domains of study. The energy balance of building provided variables connected to the thermo-physical parameters of the building and the energy consumption was evaluated by using a correlation between dimensionless numbers. Dimensional number correlation was extended to each building of the universe of buildings because the sample used has a statistical meaning. Using spatial analysis techniques and GIS, the energy consumption maps of the population of buildings were obtained [1]. The CERN has a very rich GIS database providing information about the year of construction, type of wall, type of roof, function and number of storey for each building under analysis. 2.1. Model reconstruction from LiDAR data and the hybrid approach LiDAR and GIS The 2.5-DUSMs here assumed as inputs for the extraction of urban indicators, are image-based georeferenced information. They are constructed using a hybrid approach that integrates: (1) raw LiDAR data and 2-D vector digital maps for the definition of building outlines; (2) raw LiDAR data and the 2-D projection of 3-D roof lines existing in 3-D urban models for the definition of roof outlines (this was applied to the CERN campus only, because we have a 3-D vector model). The LiDAR data used for the construction of 2.5-DUSM is classified according to the algorithms proposed by Axelsson [2]. Moreover, interpolation techniques, such as TIN, are applied to raw LiDAR data points in order to deduce terrain and building surfaces. The 2.5-DUSM constructed relies on two different assumptions: (1) terrain and buildings; (2) terrain, buildings and vegetation; the purpose of each depends on the type of application defined, for instance, on solar analysis along building roofs. A normalized 2.5-DUSM of buildings (representing the height of each building) is also interpolated by subtracting the altitude of terrain to the model representing the altitude of buildings. This type of model is used for the extraction of morphological properties of buildings, such as the area of facades, area of roofs and volume [3], [4].

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

2.2. Energy analysis based on the use of Digital Image Processing (DIP) techniques Once the urban model is reconstructed, it can be analysed with dedicated DIP techniques and mathematical scripts aiming at computing Urban Environmental Quality (UEQ) indicators. In particular, the urban model can be considered a raster image, where the intensity value of each pixel contains the information about the height of the pixel itself. Tools for the analysis and evaluation of the urban texture were implemented at the University of Cambridge in the 1990s [5], [6], [7] and further developed at the Senseable City Laboratory at the Massachusetts Institute of Technology in Boston [8]. The energy analysis includes here three parts: the estimation of energy needs for heating, artificial lighting and the electrical and thermal energy production from sun collectors. Inputs for this analysis are the models and a series of masks obtained from LiDAR data and GIS datasets, energy assumptions for building types according to the building class of age and environmental data referred to the locations. In both case studies different classes of age were established, according to the information stored in the two databases. Outputs of the analysis are visual maps and numerical data to be used to provide energy scenarios. A. Heating needs calculation (figure 2) The model computes the monthly energy requirement building by building for the heating period, taking into account the effects of mutual shadowing by the urban fabric. Results are stored in a data structure and these can be visualised either for the whole case-study area or for each building, or for each storey of the same building. Buildings are sliced at 3 meters intervals in order to consider each building storey. This subdivision allows to assign different uses to spaces. In this paper the residential use is considered. The core function calculates thermal losses and gains through the building envelope of each thermal zone corresponding to each storey. This function is repeated for every slice of every building. The heating period is provided by climatic data of the location. Two different internal climatic conditions for the heating period are set in order to simulate the intermittent regime of the heater during the day. As suggested in CEN standards for indoor air quality [9], the temperatures are set as follows: 20°C temperature and 50% relative humidity for the time span between 7 AM and 11 PM; 18.5°C and 50% relative humidity for the remaining hours. The input data from the two databases are the following: (a) thermal parameters of different materials according to the class of age of buildings (the transmittances of horizontal and vertical opaque and glazed surfaces, the transmittance of the ground floor, the conductivity of the ground, the solar transfer coefficient of the window glasses, the thermal capacity of the wall), (b) some constructive characteristics of the buildings (glazing ratios, external wall thickness). In case some accurate data is not available, the minimum values are set

according to the standards. In particular building geometry is provided by 2.5-DUSM. Initially, some geometrical quantities have to be estimated from the 2.5-DUSM. For each building, indeed, it is possible to derive the floor area, the volume and the lateral surface just using basic DIP techniques and matrix operations. Then thermal gains and losses of the side-walls, the ground floor or the top floor are computed. Heat losses through external surfaces – both caused by transmission and ventilation – are carried out. Thermal gains are split into internal and solar gains. Internal gains are computed referring to UNI/TS 11300-1:2008 Standard [10] taking into account different time intervals connected to building zones utilization. Solar gains related to both opaque and glazed surfaces depend on the solar radiation intercepted by the external building envelope, on the surfaces orientation and inclination and presence of surrounding buildings. A 3-D array stores the information containing the time percentage when each pixel is obscured by the surrounding buildings. The Sky View Factor (SVF, i.e. the visibility of the sky vault) calculation for each façade pixel is computed aiming at defining the correction factor to be used in order to consider the urban geometry in the solar gain estimation. The monthly and seasonal energy balance for all the buildings is carried out. For each building and each storey thermal needs are computed taking into account the intermittency and the efficiency of the heating system and the utilization factor of total heat gains. ENERGY ASSUMPTIONS: BUILDING DATABASE: - ID of building; - year of construction - use of the building - geometry

ENVIRONMENTAL DATA:

ASSUMPTIONS ABOUT THE YEAR OF CONSTRUCTION : -U-values of opaque and transparent surfaces; - GRs for different orientations - wall thickness - thermal capacity of walls

2A HEATING MASKS: 2.5 DUSM BUILDINGS BUILDING IDs

1. 2. 3. 4. 5.

Calculation of heat loss coefficients: H=Ht+Hg+Hv [kWh/m2yr] Calculation of heat losses: Ql = Qt+Qg+Qv [kWh/m2yr] Calculatio of free contributions: Qg = (Qi+ Qsi) [kWh/m2yr] Calculation of the utilisation factor η Energy needs of the building Qh = Ql - η*Qg [kWh/m2yr] Primary energy needs of the building Q [kWh/m2yr]

NUMERICAL OUTPUTS: Energy needs Q Qh ... VISUALIZATION OUTPUTS: energy maps SVF map

Figure 2: Heating calculation structure

B. Artificial lighting needs evaluation (figure 3) The simulation runs during the winter season and takes into account a time span from 9 AM to 5 PM to compute useful daylighting contributions. For the other hours of usage, an estimation of consumptions was made taking into account typical space utilisation patterns and occupancy rates during the day. The model used in this study is presented in Morello et al. 2009 [11] and here summarized. It is 2 based on the computation of solar irradiances (W/m ) intercepted on vertical urban surfaces [12]. The contribution of beam and diffuse irradiation at each point is derived using Ratti and Richens (2004) [6] shadow casting routine, which allows to distinguish among lit and shadowed pixels on the facades of the urban model. In particular, the beam contribution of irradiance is summed to the diffuse, only for lit pixels.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Moreover, the model is sliced at every storey (3 meters intervals are used) in order to account for solar admittance variations of vertically aligned pixels. Irradiances are then converted into illuminance values (lx). Illuminances spread out inside the building whereby the model considers a constant Glazing Ratio (GR) applied to all orientations and with openings run uninterruptedly along all the perimeter of the buildings. Hence, referring to the total flux method [13], the luminous flux φt (lm) entering the room can be calculated. The daylighting level dramatically drops with the increase of distance from the openings. We refer to literature (digital simulations and measurements) to derive simplified daylight factor’s profiles in indoor spaces assuming these identical over all orientations [14]. We calculate internal illuminance profiles on the passive zones only [7]. In this case, we define as passive zones the floor areas within a distance to the external perimeter that is twice the height of the ceiling, hence e.g. 6 meters. Once the patterns of indoor illuminance levels are mapped, the integration of natural and artificial lighting can be assessed. The model computes the 2 average hourly energy consumption in Wh/m over the passive zones required by the integration of 2 artificial lighting, whereas it assumes 5 W per m as the general electrical consumption for artificial lighting in the non-passive zones where full electric lighting system is always provided: this value is calculated considering a 100 W lamp that covers an 2 area of about 20 m whereby also unlighted floor areas occupied by furniture or facilities are included in this estimation. A threshold of minimum illuminances over the work plane have to be guaranteed, otherwise artificial lighting has to be provided. We assume 100 lux as the minimum illuminance that has to be reached on every point of space. Even if this threshold does not represent a high level of illuminance and is usually provided in spaces that do not require specific visual tasks, though it constitutes a good average limitation if spread out on all points of the building. ENERGY ASSUMPTIONS: BUILDING DATABASE

ENVIRONMENTAL DATA: - geodata (latitude) - statistical climatic data

ASSUMPTIONS FOR THE LIGHTING MODEL: - GRs for different orientations - hours of usage - common el. consumption for lighting - minimum illuminance for indoors

2B LIGHTING MASKS: 2.5 DUSM BUILDINGS BUILDING IDs ORIENTATIONS

- Assessment of beam radiation on vertical pixels with DIP technique (shadowing routine); -Assessment of global incident solar irradiation on pixels (solar geometry); - Irradiances are converted into illuminance values; - Calculation of the luminous flux using the total flux method; - Estimation of daylight factor’s profiles in indoor spaces; - Computation of the ave. hourly energy consumption needed for el. lighting as a compensation to natural lighting to reach minimum illuminance threshold.

NUMERICAL OUTPUTS: Daylighting VISUALIZATION OUTPUTS: daylighting maps -Percentage of irradiated facades (annual, monhly, daily, hourly maps) -- illuminance maps indoors

Figure 3: Artificial lighting calculation structure

C. Solar radiation calculation (figure 4) Solar geometry formulae allow deriving hourly global irradiation on inclined surface (Ig h) from the beam (Ib h), diffuse (Id h) and ground reflected (Ir h)

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components of hourly radiations for every orientation and inclination of surfaces. As meteorological input of radiation on horizontal surface, we used the database Meteonorm ® that generates statistical data for the period 1980-2000 for many cities in the world, and thus for Geneva and Florence. However, calculating irradiation for each hour and for each pixel of a high resolution 2.5DUSM model would result of several days of computer time simulation. Consequently, we reduced our solar irradiation dataset by averaging hourly values for each month. We compared in Geneva the irradiation results from applying strictly and average hourly: the relative error is statistically very few significant particularly for the south oriented surfaces. The model of diffuse component on inclined surface should be selected very carefully so as to take into account the anisotropy of the phenomenon. Among the numerous anisotropic models, those of Perez [15] and Hay [16] are the most common. The model of Hay was chosen as it is particularly addressed to the use of average hourly values as explained above. Both of the main components of the global irradiation – direct and diffuse – are multiplied by a shadowing factor according the following formulae: - Shadowing on direct component (Sb h) at a given hour {0, 1}: The same shadow casting routine as the one mentioned above (in 3.2/B) is applied to the input masks of roofs. - Shadowing on diffuse component (Sd) [0, 1]: the calculation of the Sky View Factor (SVF) on the model evaluates the reduction of the sky visibility from the roof point of view due to obstacles in the surrounding environment. It is thus not timedependent. Hence, when we are able to determine for every pixel its shadowing condition, its SVF, its orientation and its inclination, we can assign the global incident solar radiation calculated in W or J/m² for various time scales (hour, aggregation to month, year). Finally, from the global irradiation and on the pieces of building roof where irradiation is sufficient 2 (defined as > 1000 kWh/m yr) and the area is 2 significant (>20 m ), it is possible to calculate electrical and thermal energy production from sun collectors. For most of the common technologies of poly- and mono-crystalline, an electrical production equivalent to 9% of the global irradiation is considered. For the calculation of thermal production for heating and DHW (with glazed and unglazed collectors) the formulae used in the software EnerCAD ® [17] were implemented in the image processing script. The calculation is made for the hours when outside temperature is below 16°C (heating cut off).

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Legend [MJ]: ENERGY ASSUMPTIONS:

ENVIRONMENTAL DATA:

1511…50000 50000…250000

BUILDING DATABASE

250000…500000

ASSUMPTIONS ABOUT SOLAR IRRADIATION

500000…1000000 1000000…2884762

2C SOLAR IRRADIATION MASKS: 2.5 DUSM BUILDINGS BUILDING IDs

1. Calculation of hourly beam, diffuse and reflected components on inclined surface from such components on horizontal surface and pixel orientation and slope (solar geometry formulae).

NUMERICAL OUTPUTS: Energy needs Q Qh ...

North

2. Calculation of hourly shadowing on beam radiation and shadowing on diffuse radiation : Sb h = {Pixel_in_light = 1; Pixel_in_shadow = 0} Sd = SVF [0, 1] 3. Calculation of hourly global irradiation on inclined surface: Ig h = Ib h*Sb h + Id h*Sd + Ir h 4. Calculation of electrical and thermal energy production: EPV h = 0.09* Ig h Eheating h = f(Ig h, Texternal, Tinternal, Tdistribution, Arearoof)

VISUALIZATION OUTPUTS: solar maps (annual, monhly, daily, hourly maps) SVF map

Figure 4: Seasonal energy needs for heating visualized in 2-D on the CERN campus (MJ) and in 3-D in Florence (MJ)

Figure 4: Solar irradiation calculation structure

3. RESULTS AND DISCUSSION Two types of outputs were produced: numerical data and visualizations. Visualisations are fundamental in order to communicate and to program interventions in the decision making process and this is a novelty at the urban level. The great flexibility of the proposed method to interactively classifying features in many ways allows the production of a great number of thematic maps covering all the study area to highlight the distribution of: heat production structures; building geometry properties; building energy needs (thermal and lighting). Among the produced thematic maps we can mention: estimated Heat Power [kW]: partitioning of buildings to different age construction classes referring to estimated heat 2 power; energy consumption per m ; partitioning of buildings to different classes referring to energy consumption for square meters; available Heat Power [kW]: partitioning of buildings to different classes referring to available heat power and number 3 of installed plants; building Volume [m ]: partitioning of buildings to different classes referring to their volume; Form Factor (ratio between all the thermal -1 dispersing surface and volume) [m ]: partitioning buildings into eleven classes referring to their Form Factor; building height [m]: partitioning of buildings into different classes referring to their height; classes of construction age of buildings; daylighting and solar irradiation distribution. A series of 2-D and 3-D maps showing the energy needs and potential energy production follow (figures 4, 5, 6).

Figure 5: Annual solar irradiation (kWh/m2 yr): above, values are grouped for each roof on the CERN campus; below, the representation of irradiation on a pixel basis for the Florence case study.

Figure 6: Hourly shadowing (October 15th, 9 AM) map used for the determination of the pixels in shadow on the CERN campus

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

4. CONCLUSIONS AND FUTURE WORK The proposed method collects different and important analysis in one tool. It can be implemented by commercial software but it can also be easily adapted to use free open source software. It is dynamic because it allows to take into account new data and to reproduce visualizations to show the upto-date situation, giving powerful tools to investigate distribution of energy needs and solar irradiation accesses at the urban level. The update of the input data is fast, easy and cheap. It can be applied to several situations, it is friendly adaptable and it does not require high computation time and high PC performance (a PC with 7– 9 GB RAM is sufficient). Data and information used can be different from those used in the present work: after a strong check on the quality of the input data, the robustness and the efficacy of the method and the results accuracy are however guaranteed. Future work will expand the energy analysis to the estimation of needs for cooling, which is a fundamental issue in the overall energy balance of cities and is highly dependent on urban geometry aspects. More user-friendly interfaces and a higher integration among the software used are also desirable.

5. ACKNOWLEDGEMENTS We would like to thank the Territorial Information System (SIT) of Florence Municipality and the international organization CERN, hosted in Geneva, Switzerland, for providing us the information and data needed to run the analysis.

6. REFERENCES [1] Balocco C., Grazzini G., Andreani G., Rational Use and Energy Planning: A Thermodynamic and Geographical Approach, in “Energy Efficiency Research Advances”, Chapter “Research and Review Studies”,pp.11-62, NOVA Publ.Ed. D.M. Bergamann, N.Y. 2008. [2] Axelsson P., 1999, Processing of laser scanner data - algorithms and applications. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol. 54, 138-147. [3] Carneiro C., Morello E., Desthieux G., 2009, “Assessment of solar irradiance on the urban fabric for the production of renewable energy using LIDAR data and image processing techniques”, in Sester M., Bernard L., Paelke V. (editors), Advances in GIScience, Lecture Notes in Geoinformation and Cartography, Springer, Berlin. [4] Carneiro C., Morello E., Voegtle T., Golay F., 2010, “Digital urban morphometrics: Automatic extraction and assessment of morphological properties of buildings”, in Transactions in GIS, 14 (4), 497-531.

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[5] Ratti, C. (2001). Urban analysis for environmental prediction. Cambridge: University of Cambridge. [6] Ratti, C., & Richens, P. (2004). Raster analysis of urban form. Environment and Planning B: Planning and Design , 31 (2), 297-309. [7] Ratti, C., Baker, N., & Steemers, K. (2005). Energy consumption and urban texture. Energy and Buildings, 37 (7), 762-776. [8] Morello, E., & Ratti, C. (2007). Raster Cities: image processing techniques for environmental urban analysis. In K. Thwaites, S. Porta, & O. Romice (Eds.), Urban Sustainability through Environmental Design: approaches to time, people and place responsive urban spaces (pp. 119-122). London, UK: Spon Press. [9] EN prENV 1752: 1996. Ventilation of buildings. Design criteria for the indoor environment. [10] UNI - TS 11300-1:2008. Energy performance of buildings – Part 1: Evaluation of energy need for space heating and cooling. [11] Morello E., Ratti C., 2009, “SunScapes: ‘solar envelopes’ and the analysis of urban DEMs”, in Computers, Environment and Urban Systems, 33 (1), pp. 26-34. [12] Carneiro C., Morello E., Ratti C., Golay F., 2008, “Solar radiation over the urban texture: LIDAR data and image processing techniques for environmental analysis at city scale”, in Lee J., Zlatanova S. (editors), 3D Geo-information Sciences, Lecture Notes in Geoinformation and Cartography, Springer, Berlin. [13] Szokolay, S. V. (2004). Introduction to architectural science: the basis of sustainable design. Amsterdam, Boston: Elsevier, Architectural Press. [14] Krarti, M., Erickson, P. M., & Hillman, T. C. (2005). A simplified method to estimate energy savings of artificial lighting. Building and Environment, 40, 747–754. [15] Perez, R., Ineichen P., Seals R., Michalsky J., Stewart R. (1990). Modeling Daylight Availability and Irradiance Components from Direct and Global Irradiance. Solar Energy 44 (5), 271-289 [16] Hay, J.E., (1979). Calculation of monthly mean solar radiation for horizontal and inclined surfaces. Solar Energy 23, 301–330. [17] Lachal, B., 200, ENERCAD, calcul de la production de chaleur de capteurs solaire sur une base mensuelle. Rapport du CUEPE de l’Université de Genève.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

An Interactive Performance-Based Expert System for Daylighting Design Jaime M. L. GAGNE1, Marilyne ANDERSEN2, Leslie K. NORFORD1 1

2

Building Technology Program, Massachusetts Institute of Technology, Cambridge, MA, USA Interdisciplinary Laboratory of Performance-Integrated Design (LIPID), Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland

ABSTRACT: Architects are increasingly using digital tools during the design process, particularly as they approach complex problems such as designing for successful daylighting performance. However, while simulation tools may provide the designer with valuable information, they do not necessarily guide the user towards design changes which will improve performance. This paper proposes an interactive, goal-based expert system for daylighting design, intended for use during the early design phase. The expert system consists of two major components: a daylighting knowledge-base which contains information regarding the effects of a variety of design conditions on resultant daylighting performance, and a fuzzy rule-based decision-making logic which is used to determine those design changes most likely to improve performance for a given design. The system gives the user the ability to input an initial model and a set of daylighting performance goals in the form of illuminance and daylighting-specific glare metrics. The system acts as a “virtual daylighting consultant,” guiding the user towards improved performance while maintaining the integrity of the original design and of the design process itself. Keywords: daylighting, expert system, design process

1. INTRODUCTION Designers have long considered daylight as an important aid for architectural expression. In recent decades, we have come to understand that daylighting may provide additional benefits, such as reduced energy consumption and improved occupant health and well-being [1,2,3]. Nevertheless, simply providing daylight in a building will not always result in positive results. Daylighting is only as good as its delivery system, so careful design is necessary to ensure that enough light is available and that glare, shadows, and reflections are reduced [4]. Unfortunately, it is often a challenge to create a successfully daylit building. Digital tools offer new ways of helping architects create or find designs with high levels of daylighting performance using efficient and intelligent guided design exploration methods. Optimization algorithms are a common solution, largely because they have the capabilities necessary to find or generate successful solutions; however, these methods generally do not allow for user-interaction. As it is highly unlikely for a designer to simply accept a design generated by an optimization algorithm, a better approach would be a more interactive search method, which would accept input from a designer and which would grant the designer a larger degree of control. An example of such an approach is a knowledgebased or expert system. An expert system is one in which human expert knowledge about a specific domain is encoded in an algorithm or computer system [5]. In the daylighting domain, such a system

would function as a virtual lighting consultant, guiding the designer towards design modifications which improve overall daylighting performance. Knowledgebased systems have already been successfully implemented for artificial lighting scenarios [6,7]. For daylighting, a few simple expert systems exist. The Leso-DIAL tool provides users with a “qualitative diagnosis” using an expert system based on fuzzy logic rules [8]. The NewFacades approach considers energy and visual comfort based on a prescription energy code for hot climates to suggest a range of facade solutions to the designer [9]. These systems represent first steps in expert systems for daylighting in design, but they do not allow for a comprehensive understanding of daylighting or a large amount of user interactivity. This paper will describe a user-interactive expert system approach which enables a comprehensive analysis of daylighting. This approach includes two climate-based performance metrics, one for illuminance and one for daylighting-specific glare, in order for the designer to have an understanding of the amount of light and the visual comfort in the space. The method begins with a designer's own initial design and performance goals. It then evaluates the performance of the design and creates a series of suggestions for design changes which are likely to result in improved performance, thus enabling a search process that is highly specific to the user's design problem. Decisions are made using an expert system which is comprised of a precalculated database of daylighting-specific information connected to a set of fuzzy daylighting expert rules. Any design decision that the designer chooses to allow will be automatically generated in

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the original model and the new performance will be calculated. The designer is allowed to interact with the system during an iterative search process that is both agreeable to the designer and likely to improve the performance of the design.

2. EXPERT SYSTEM FOR DAYLIGHTING The expert system described in this paper is a fuzzy rule-based system combined with an external database of previously computed daylighting simulation data, called the daylighting knowledgebase. This system has been implemented as a functional tool within the Lightsolve project [10]. 2.1. A Daylighting Knowledge-Base Most expert systems are traditional systems in the sense that they are populated using knowledge from a human expert, and as a result, such systems are restricted in terms of accuracy and complexity. To create an expert system capable of more sophisticated analysis, the expert system described in this paper uses a daylighting-specific database, or “knowledge-base,” which has been populated using data from a set of completed daylighting simulations. These simulations were performed for a set of 512 models with differing facade characteristics, based on the Design of Experiments method [11]. For each model, the illuminance and a model-based approximation of the daylight glare probability (DGPm) [12] were calculated in five different zones within the space (and four different views from within each zone for the glare metric), over the whole year. These climate-based metrics were calculated using the Lightsolve Viewer (“LSV”) [13], the simulation engine native to the Lightsolve program. The knowledge-base contains information about the relative effects of ten different facade parameters on each of the two daylighting metrics from the various zones and views within the space. The ten different façade parameters considered are: window area, window height-to-width ratio, vertical and horizontal location of windows on the façade, window distribution (how close or far apart windows are to each other), total number of windows, length of horizontal overhangs and/or vertical fins, glass transmissivity, and glass type (regular or translucent). By using calculated data rather than heuristics to populate the knowledge base, the expert system can consider highly specific goals and multiple sets of goals for the same design, which can differ based on the daily time period(s), season(s), or zone(s) of interest within a space. It also allows for more logical and accurate comparisons of multiple design options than mere heuristics. A more detailed explanation of the knowledge-base can be found in [14]. The knowledge-base used in this paper used simulations from Boston, MA (USA). 2.2. Expert System User Inputs The expert system rule base is a decision-making algorithm that assesses specific design situations and creates lists of suggested design changes which should improve the current performance. The rule

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base uses fuzzy logic [15], which allows it to better emulate the human thought process than classical logic. It has been developed to be a flexible algorithm which can accommodate a wide variety of initial design scenarios. The system was also created in such a way that it requires user interaction and user inputs in order to function. The major user input is a 3d model of an original design with sensor planes for illuminance and/or glare. Additionally, performance goals for each sensor plane must be specified. For each illuminance sensor plane, the user must specify a desired illuminance goal range in lux, including the actual desired range and a buffer zone of acceptable values. For example, the user may desire the illuminance of a given sensor plane to fall between 400 lux and 1200 lux, but he or she will also accept illuminances as low as 200 lux and as high as 1500 lux. For each glare sensor or glare sensor group, the user must choose a glare tolerance. The glare tolerance options are “zero” (which means that no glare is tolerated), “medium”, and “high” (which means that a high amount of glare is allowed). These tolerance values correspond to the three glare ratings of “perceptible”, “disturbing”, and “intolerable” glare described by Wienold in [16]. In addition to the 3d model and performance goals, the user must also several other inputs. One set of inputs is the set of priority levels for each performance goal. The priority level is a number from 1 to n, where n is the total number of sensors. The highest priority value is 1, and multiple goals may have the same priority. The user must also select a window uniformity scheme from three possible choices: “All windows in the model should look the same”, “All windows on a façade should look the same”, or “Windows can look different from other windows on the same façade.” Finally, the user must indicate times and seasons of interest (the choices are: winter, fall/spring, summer, morning, mid-day, and afternoon) and input the latitude and a weather file for the desired location. 2.3. Fuzzy Sets and Rules After the user has begun the expert system process, the LSV engine is used to calculate goalbased performance metrics for both illuminance and glare. This information, along with the original user inputs, is used to create sets of fuzzy variables, which help to describe the current scenario. These fuzzy sets are: userPriority (high and low), sensorPerformance (good and bad), illuminanceSensorPerformance (too high and too low), glareSensorPerformance (too high), and distanceFromGoal (close and far). In addition to these fuzzy variables, the system also creates a customized knowledge-base, which is a subset of the knowledge-base described in section 2.1 that contains only the information most relevant to the current design. Based on this customized knowledge-base, each potential design action is given values for the fuzzy set actionResult (Fig 1). These fuzzy variables refer to the likely result of the given design action on a given sensor, for example

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

“Large Illuminance in Illuminance”. Each sensor in the model will have a unique actionResult fuzzy set. Once the fuzzy variables have been created, they are used to fire a series of fuzzy rules. The result of this process is a set of design actions which has been ordered based on which actions are most likely to improve the performance of the current design based on the user’s goals and preferences. The rules are fired in four steps: 1. Determine priority of each sensor. For example, IF SensorPerformance is Bad AND UserPriority is High, THEN SensorPriority is High. 2. Determine which change(s) will improve performance, based on the current scenario. For example, IF SensorPriority is High AND SensorType is Illuminance AND IlluminancePerformance is TooLow: (a) IF distanceFromGoal is Far, THEN DesiredChange is “Increase Illuminance by a Large Amount”; (b) IF distanceFromGoal is Close, THEN DesiredChange is “Increase Illuminance by a Small Amount”. 3. Evaluate each possible design action in the customized database using the desired changes determine in Rule Base 2. For example, IF DesiredChange is “Increase Illuminance by a Large Amount” AND ActionResult is LargeIncrease, THEN action is GoodForSensor. These rules are fired once per potential action, and once per sensor. 4. Each potential action is ranked based on how likely it is to improve each sensor and the sensor priorities. The final step is to sort the set of design actions from highest to lowest rank. The first design actions in the list will be those actions most likely to produce positive performance results in the current design, while those actions at the end of the list are likely to decrease overall performance.

Figure 1: Membership functions for ActionResult fuzzy set.

2.4. System Implementation and Process The expert system has been implemented within the framework of the Lightsolve project. Google SketchUp [17] is used as the 3d modeller, and the embedded Ruby application programming interface (API) within SketchUp is used to create pop-up interfaces which allow the user to enter the initial inputs and to perform the major processes and calculations. The LSV simulation engine is a standalone executable which is called directly from within the SketchUp/Ruby environment.

Figure 2: Schematic diagram of expert system process.

The expert system has a functional, stand-alone interface which allows designers to interact with the system (Fig. 3), which has been implemented using Adobe Flash. The interface has been designed to provide an intuitive and clear way of communicating the current performance of a design and the list of changes suggested by the expert system. The interface also allows designers to view the performance of their design over multiple iterations of the exploration process. The overall expert system process is shown in Figure 2 and consists of the following steps: 1. The user creates an initial 3d model of a design with illuminance and/or glare sensor planes and specifies all necessary initial inputs to the system (using pop-ups in SketchUp). 2. Daylighting performance for the current model is calculated using the LSV engine based on the user’s illuminance and glare goals. 3. The knowledge-base described in section 2.1 is used to create a customized database which contains only the information most relevant to the current design. 4. Information about the user’s preferences, the original 3d model, the current performance, and the customized knowledge-base is used to create the fuzzy variable sets. 5. Fuzzy rules are fired using the fuzzy variables. The results are a set of suggested design changes that the system will propose to the user in order to improve performance. 6. Results are presented to the user in the user interface (Fig. 3). 7. The user selects a design change to make, and a new 3d model is created automatically. The process begins again starting at step 2. 2.5. An Expert System Design Process The user’s process begins when he or she creates an initial 3d model in SketchUp and initiates the expert system. Once the first set of simulations is complete, the user interface will automatically open. From there, the user’s design process is as follows: 1. From the expert system interface, the user can view a list of suggested design changes that can be made to his or her initial model. The user may skip

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forward or go backwards between the various options on the list before choosing one. 2. After the user selects one design change to try, the expert system will automatically make the selected change to the 3d model, which should still be open in SketchUp. The expert system will make three different magnitudes of the selected change. For each change, the expert system will create and save a new 3d model, run the LSV engine, and calculate the goal-based performance. 3. After the three different magnitudes of change have been simulated, the expert system will display all three results in the interactive graph within the interface. The user may browse the views of the current design and the temporal maps to see how the performance and design have changed in each of the three options. The user must choose one of the three possibilities before continuing to the next design iteration. 4. After one or more design iterations have been made, the user may then choose either to select a new design change to try from the list presented by the expert system, or the user may return to a previous iteration of the design (including the initial model). If the user elects to make another design change, steps 2 and 3 repeat. 5. After several iterations, the user should be able to view the progressive performance of the design. The user may stop the process at any point.

3. EXPERT SYSTEM EVALUATION The main function of the expert system described in this paper is to effectively guide a user towards improved daylighting performance of an original design. It is of critical importance that users have confidence in the advice given to them by the

system, so a high level of performance is essential. Although the expert system differs from a traditional optimization algorithm due to its domain-specific and user-interactive nature, it should be capable of performing similarly to an optimization algorithm in a best case scenario. In order to assess the behaviour of the expert system, a series of case studies were completed which compare the performance of designs found using the expert system to high performing benchmark designs generated using a genetic algorithm (GA). This paper will describe the results of two case studies, which both have two illuminance goals. These case studies were considered for Boston, MA (USA). Although they are not presented here, additional case studies were also completed which consider other situations, such as conflicting illuminance and glare goals. These studies can be found in [18]. The GA used in these case studies was a microgenetic algorithm [19], which is a GA which uses a very small population size. For comparison purposes, the micro-GA was implemented within the Lightsolve system and uses the same 3d models and performance metrics as the expert system. This system is described in more detail in [20]. 3.1. Case Study Procedure A set of study procedures was developed to better compare results from the expert system to the GA, given their differences in algorithm type. While a GA is one that generates designs, the expert system always assumes that an initial design is given and suggests design changes based on the current design. The following procedure was used: • Micro-GA procedure: An initial massing model with no windows was used to generate a new model

Figure 3: Performance analysis and decision making interface for the expert system. Views of the current design are shown (top left) along with annual performance in temporal map form (top right). Performance over multiple iterations is shown in the interactive graph (lower left). Expert system design suggestions are given in the lower right.

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of each generated design. The algorithm was run for ten generations before stopping. If a perfect solution was not found, the best design was considered that with the highest performance found over all generations. • Expert system procedure: An initial model was created with generic rectangular windows. This initial model was designed to be of mediocre performance, so as to avoid starting out with an initial design whose performance was very poor or very good. For these case studies, a “perfect user” was assumed. The “perfect user” was defined as one who would select the first suggested design change at each iteration and the best performing magnitude of each design change. The “perfect user” scenario was also one in which the process continued even if performance decreased after a given design iteration. The algorithm was run for ten design iterations before stopping. As with the GA study, if a perfect solution was not found, the best design was considered that with the highest performance found over all completed iterations.

facades of interest (west and south). The performance goals for this case study were: • South zone: 400 lux minimum preferred (200 lux accepted); No maximum. • West zone: No minimum; 500 lux maximum preferred (800 lux accepted). Based on these goals, the known design solutions to this problem featured small, shaded windows on the west facade and larger windows on the south façade.

3.2. Case Studies

The second case study features a trapezoidal space (Fig. 5) where the two facades of interest, north and south, are perpendicular to the two sensor planes. The performance goals for this case study were: • East zone: 200 lux minimum preferred (100 lux accepted); 800 lux maximum preferred (1200 lux accepted) • West zone: 400 lux minimum preferred (200 lux accepted); No maximum. For this case study, it was assumed that good solutions would have windows on both facades shifted towards the west sensor. For both case studies, the best performing designs found after ten generations or ten design iterations are shown in Figure 6. For the L-shaped space, both the expert system and the micro-GA were able to find designs which were close to

Figure 4: Massing model and sensor plane locations for Lshape case study.

This paper will present two case studies, which both have two illuminance goals. The first case study features an L-shaped space (Fig. 4) where the two sensor planes are located roughly parallel to the

Figure 5: Massing model and sensor plane locations for trapezoidal case study.

Figure 6. Average performances for the starter expert system design, final expert system design, and final microGA design for both case studies.

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meeting the performance goals entirely. As expected, both “best” designs have either very small or highly shaded windows on the west facade with larger or less shaded windows on the south facade. For the trapezoidal case study, both algorithms had more difficulty finding good solutions. In this case study, the micro-GA was able to find a solution which performed about 5% higher than the expert system. This difference is due to the window uniformity scheme selected for the expert system (all windows on the facade must be uniform) and the univariate (“step-by-step”) nature of the expert system algorithm. While the micro-GA found a design solution that features windows clustered towards the west end of both facades as expected, the expert system focused on changing the properties of the windows without moving them. These case studies demonstrate that the expert system is successful at improving the performance of designs for two illuminance goals. The difference in performance between the expert system and the GA was small (4.4% at most) and acceptable given the fact that the expert system was designed with user interactivity in mind, while the GA was not.

4. CONCLUSIONS This paper presented a new user-interactive expert system approach which enables architects to consider daylighting goals in the early design stages by engaging them in a performance-driven design exploration process. The expert system was shown to be successful at making design decisions which improved the daylighting performance of two case study designs. In both of these case studies, the performances of designs found using the expert system were comparable to those generated by a micro-genetic algorithm (micro-GA). In addition to the case studies presented in this paper, additional case studies which consider more complex scenarios such as conflicting illuminance and glare goals were also completed. The expert system has also been tested on a group of designers who were asked to complete a design task with the system and to evaluate their experiences using the tool. These additional results will be presented in future papers.

5. REFERENCES [1] Rashid, M. and Zimring, C., 2008. A review of the empirical literature on the relationships between indoor environment and stress in health care and office settings: Problems and prospects of sharing evidence. Environment and Behavior, 40(2), pp.151–190. [2] Edwards, L. and Torcellini, P., 2002. A literature review of the effects of natural light on building occupants. NREL. [3] Boyce, P., Hunter, C., and Howlett, O., 2003. The benefits of daylight through windows. U.S. Department of Energy.

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[4] Boyce, P., Heerwagen, J., Jones, C., Veitch, J., and Newsham, G., 2003. Lighting quality and office work: A field simulation study. Pacific Northwest National Laboratory. [5] Luger, G., 2004. Artificial Intelligence: Structures and Strategies for Complex Problem th Solving. 5 edition. Boston: Addison-Wesley. [6] Jung, T., Gross, M, and Do, E., 2003. Light pen: sketching light in 3D. Proceedings of 10th International Conference on Computer Aided Architectural Design Futures, Taiwan. [7] Guo, B., Belcher, C., and Roddis, W., 1993. RetroLite: an artificial intelligence tool for lighting energy-efficiency upgrade. Energy and Buildings, 20(2), pp.115–120. [8] Paule, B. and Scartezzini, J., 1997. Leso-DIAL, a new computer based daylighting design tool. Right Light 4(1), pp.93–97. [9] Ochoa, C. and Capeluto, I., 2009. Advice tool for early design stages of intelligent facades based on energy and visual comfort approach. Energy and Buildings, 41(5), pp.480–488. [10] Andersen, M., Kleindienst, S., Yi, L., Lee, J., Bodart, M., and Cutler, B., 2008. An intuitive daylighting performance and optimization approach. Building Research & Information, 36(6), pp.593–607. [11] Montgomery, D., 2004. Design and Analysis of th Experiments. 6 edition. John Wiley & Sons. [12] Kleindienst, S. and Andersen, M., 2009. The adaptation of daylight glare probability to dynamic metrics in a computational setting. In Proceedings of LuxEuropa, Istanbul. [13] Cutler, B., Sheng, Y., Martin, S., Glaser, D., and Andersen, M., 2008. Interactive selection of optimal fenestration materials for schematic architectural daylighting design. Automation in Construction, 17(7), pp.809–823. [14] Gagne, J., and Andersen, M. A daylighting knowledge-base for performance-driven facade design exploration. LEUKOS (submitted). [15] Siler, W. and Buckley, J., 2005. Fuzzy expert systems and fuzzy reasoning. John Wiley & Sons. [16] Wienold, J., 2009. Dynamic daylight glare evaluation. In Proceedings of Building Simulation, Glasgow. [17] Google SketchUp, 2010. [online] Available at: [Accessed http://sketchup.google.com/ November 8, 2010]. [18] Gagne, J., 2011. An interactive performancebased expert system for daylighting in architectural design. PhD thesis, MIT. [19] Krishnakumar, K., 1989. Micro-genetic algorithms for stationary and non-stationary function optimization/ SPIE Proceedings: Intelligent Control and Adaptive Systems. [20] Gagne, J., and Andersen, M. A generative façade design method based on daylighting performance goals. Journal of Building Performance Simulation (in press).

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A comprehensive method to determine performance metrics for complex fenestration systems Shreya DAVE1, Marilyne ANDERSEN2 1

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Building Technology Program, Massachusetts Institute of Technology (MIT), Cambridge, USA Interdisciplinary Laboratory of Performance-Integrated Design (LIPID), Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland

ABSTRACT: The ability to accurately and concisely describe the performance of complex fenestration systems (CFS) is essential to their effective implementation into the building industry. CFS are a diverse category of daylighting technologies that manipulate the light that is permitted to enter a building space. The variety and degree of dynamics that exist in the range of such technologies require a robust and flexible set of metrics that can communicate performance simply and informatively. This paper presents an approach for processing their detailed optical properties - expressed as Bi-Directional Transmission Functions (BTDF) - into a comprehensible set of metrics that can convey useful information about a system’s adherence to visual comfort and energyefficiency objectives. These metrics can then inform non-technical members of the building industry about the performance capabilities of a façade. This paper describes the novel method by which performance is evaluated, accounting for spatial and temporal variation in environmental condition. Keywords: Daylighting, energy efficiency, metrics, complex façades.

1. INTRODUCTION Solar radiation is a natural and inevitable source of light and heat for buildings. Buildings in the United States account for about 40% of total energy use, 18% of which is attributed to lighting and 33% of which is attributed to heating and cooling [1]. Intelligent use of this resource by fenestration technologies provides an opportunity to reduce a building‟s energy load attributed to window by about 41% [2]. Ultimately however, buildings are designed to provide shelter and comfort for occupants, a goal that cannot be ignored in light of optimizing energy efficiency. Complex fenestration systems (CFS) manipulate light in a number innovative ways in order to achieve balanced performance objectives. In order to facilitate the implementation of complex fenestration systems in efficient building design, a comprehensive set of metrics that relates a product with relative performance is crucial. 1.1. Problem Context While existing metrics are a suitable comparison for heat transfer and visible light transmission for conventional glazings, they are far too limited to provide useful or even relevant information for more complex glazings or for shading systems. These façade systems require a detailed description of their optical properties, typically expressed mathematically as Bi-Directional Transmission Function (BTDF) data in order to communicate their actual performance characteristic [3]. A standard BTDFs format consists of 145 incident angles relating to 145 emerging angles [4]. The challenge is to develop a robust method to manipulate this mathematical representation into a form that is not simply a set of technical specifications, but one that can inform the user concisely of annual and spatial performance in terms of energy use and occupant comfort.

Furthermore, due to the variation in technologies, it is important that, despite their necessary brevity, these metrics can still reflect information to the extent that the user can differentiate or rank them according to performance priorities. 1.2. NFRC Rating System The technical specifications for windows, doors, and skylights are mandated in the United States by the National Fenestration Rating Council (NFRC). The NFRC‟s standards require that fenestration manufacturers report the system‟s U-factor, solar heat gain coefficient, and visible transmittance based on a single predetermined set of assumptions and environmental conditions. These qualifications are then presented as absolute values to the consumer using a concise, easy-to-understand label [5]. The NFRC specifications are appropriate for describing conventional fenestration systems. Although the established set of assumptions does not explicitly represent all realistic environmental conditions, it is reasonable to expect the user to be able to extrapolate general performance expectations using intuition about local temperatures and orientation. Complex fenestration systems, however, are much less intuitive. The complexities of these systems cannot be represented with the single set of conditions because this provides no insight for accurate extrapolation. Thus, a concise but more explicit set of performance-based metrics is required to supplement physical perception. 1.3. Daylighting Metrics A number of metrics have been developed to describe how well a space performs with respect to occupant visual comfort in daylit spaces. Most fundamentally, quantitative light levels are defined for various work activities by the Illumination Engineering Society (IES) [6]. These illuminance levels were later incorporated into metrics that define

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performance for determined conditions (for a static sky type, annually, etc) such as the Daylight Factor (DF), which is defined as the proportion of outdoor light under an overcast sky that enters the space at a given location [7]. Other metrics, such as Daylight Autonomy (DA) and Useful Daylight Illuminance (UDI) use climate-based simulation capabilities to provide more realistic metrics [8, 9]. The Daylight Glare Probability (DGP) metric evaluates the quality of light in a space. It is an empirical correlation to describe the likelihood of discomfort glare due to daylight [10]. A simplified version of the DGP metric, known as DGPs, has also been identified [11]. One of the vital advantages to the DGP metric is its glare prediction for daylight specifically, as opposed to being based on electric lighting conditions.

properties of a proposed experimentation module at the Ecole Polytechnique Federale de Lausanne (EPFL), which will be built for a similar purpose of assessing the effects of various façade system designs. The generic space is a single room with one window oriented in the direction of the façade being evaluated. The window is 3 by 1.5 meters and the room is 3 meters wide, 9 meters deep, 3 meters high. The reflectances of major surfaces are 0.87 (wall), 0.87 (ceiling), and 0.13 (floor). The locations of 2 measurement sensors form a grid at each 0.65 m interval. Figure 1 provides schematic of the test space.

1.4. Adopted Approach This paper presents the methodology for calculating quantitative performance-based metrics to inform about what effects a complex fenestration system will have on the performance of the space. The complete data set will consist of analysis of five selected complex fenestration systems defined by their BTDF in each of the five orientations (north, east, south, west, and horizontal) and in fifteen climate locations that represent the variety in typical conditions of the continental United States [12]. This data will then be evaluated through a series of sensitivity analyses in order to determine the critical variables that affect ultimate performance and provide insight as to how to reduce the information into a usable form. In this paper, the criteria most relevant to the performance of a façade system – namely relative energy impact, occupant visual comfort, and view through the façade – are defined within the context of a generic space and on an annual basis. A base case scenario of a double-glazed clear window is used to normalize assumptions and to provide an intuitive reference case with which the building industry is familiar. This base case scenario, along with a sample complex fenestration system, have been used to generate an initial dataset so as to illustrate the feasibility of the proposed methodology for a given climate location.

2. PROPOSED METHOD Three performance criteria have been defined to assess the performance of a complex façade system: one addressing annual energy efficiency and based on simplified lighting and heating/cooling estimations to determine Relative Energy Impact (REI), one related to visual comfort and approximated as a new metric named Extent of Comfortable Daylight (ECD), and one related to the ability to view through the system and approximated as a new metric named View Through Potential (VTP). These three criteria are presented in the following sections. 2.1. Reference Scenarios The generic space modelled for all spatial comparisons is based on the geometric and material

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Figure 1: Test module used for spatial simulations.

The base case fenestration system is a doubleglazed clear glass window with glass layers of 3.2mm thickness and an air gap of 6.4mm. In conventional NFRC metrics, the U-factor would be 2 defined as being 3.12 W/m and the overall visible transmittance is 81% [5, 14]. 2.2. Relative Energy Impact A fenestration system affects the energy performance of a space in two fundamental ways. First, the amount of light that is permitted to enter a space will, in an ideal situation (“perfect” daylightresponsive photosensors) correlate inversely to the amount of supplemental electric lighting required. Second, the heat addition associated with solar radiation and the heat loss associated with the thermal conductivity of the façade both have an impact on the heating and cooling loads within the space. This impact is complex to assess accurately but can generally be approximated with simplified calculations. Our proposed calculation procedure addresses each aspect. Lighting We suggest that the lighting load reduction potential be evaluated based on a set of essential assumptions to describe the behavior of the operator and presence of a dimming system. These are: - Lights may be on, dimmed, or off. - The test space consists of three lighting zones, the perimeter, the middle, and the deep zone. - Lights are by default on, but if all sensors in the zone receive sufficient daylight, lights may be dimmed or off. - Lights are turned on if the average illuminance level of the time step is below 300 Lux. Lights are off if the illuminance level is above 500 Lux. Lights are dimmed if shades are drawn due to uncomfortable glare (DGP > 0.33) [10].

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

- Bulbs are assumed to consume 10 watts per square meter of floor area. Dimmed bulbs consume 7 watts per square meter. Bulbs that are off consume no electricity [15]. The thresholds for lighting conditions have been derived from minimum IES recommendations and the DGP metric for discomfort glare. According to the IES Handbook, the minimum comfortable light level in an office is about 300 Lux [7]. Maximum light levels are less well defined, but too much light presents the issue of glare. Therefore, daylight is considered uncomfortable for occupants if the DGP is above 0.33 which is the point at which blinds are assumed to be drawn [10]. Estimation of the total amount of electricity is determined from simulations that integrate weather data with the façade‟s angle-dependent transmissivity to determine the indoor illuminance and DGP values for each moment of the year in order to suggest the amount of electricity required to light the space comfortably. It is then possible to determine a value for the annual electricity required for the space for the base case window scenario and thus each complex fenestration system as compared to the base case. Heating and Cooling The 2001 ASHRAE Handbook of Fundamentals defines energy flow through a fenestration product, neglecting humidity difference, as being the difference between heat flow in due to solar heat gain and heat flow out across the surface of the fenestration [16]. This net heat flow is calculated for each moment of the year. At each moment, the Solar Heat Gain Coefficient is calculated by first determining the solar position for each hour and applying the associated solar transmittance derived from the BTDF. It is then multiplied by the corresponding total incident irradiance using a global vertical irradiance model proposed by Hay and McKay [17]. The U-factor is calculated as a function of the hourly exterior temperature based on the heat transfer model embedded in LBNL‟s WINDOW 6 software [18]. Previous versions of WINDOW are used to calculate the single U-factor value for submission to the NFRC certification. The hourly climate data used both for the Solar Heat Gain Factor and U-Factor calculations determined from the typical-meteorological-year values (TMY3) provided by the US Energy Information Administration [18]. These represent the typical weather for a representative city in each of fourteen climate zones [19, 12]. At each climate location, 56 representative moments have been calculated to represent the year [22]. Weather data is binned and averaged into 56 periods and all calculations are based on this data set. The AHSRAE Degree-Day method for annual energy load suggests binning days into Heating Degree Days (HDD) or Cooling Degree Days (CDD) [16]. Karlsson et al. propose a simple annual energy model derived from this heat flow equation that allows for comparison of window performance [20]. Using the structure proposed by Karlsson et al. and

the assumptions of the Degree-Day method, we propose a method that first determines whether the net heat transfer is contributing to the energy load or to the energy efficiency of the space. Each day is identified as being a HDD or a CDD, so that the energy flow due to the fenestration is applied as contributing to or reducing the building‟s heating or cooling system accordingly. Summing these load contributions and reductions for the year yields a single number that characterizes the CFS‟s contribution to annual energy performance. 2.3. Occupant Visual Comfort While occupant comfort is a very subjective concept, quantitative suggestions have been made to define lighting conditions based on the avoidance of visual discomfort. Drawing on the literature as before, a minimum illuminance threshold of 500 Lux represents the lowest acceptable light levels for an office space [7]. Intolerable glare has been identified as a DGP of greater than 0.42 [10]. We propose a definition for the Extent of Comfortable Daylight (ECD) metric as the percentage of floorplan over the year which experiences comfortable daylight conditions within this range. The upper threshold in the ECD metric is thus defined with respect to uncomfortable and intolerable glare, and the lower threshold with respect to suitable illuminances. In order to simulate the threshold of acceptance, credit is assigned on a linear basis of semi-discomfort range from 200 to 500 Lux and 0.33 to 0.42 DGP. All light levels are determined from Radiance simulations, and the data analysis is conducted with MATLAB. If both the minimum illuminance target and maximum glare probability are achieved at a given time, the sensor location receives a credit of 1. If not, it receives a credit of 0, with fractional credits for the buffer range. Thus, for each moment of the year, we can identify how much of the space is “comfortably lit” as a percent of area. The ECD of a space will then represent a condensed version of information in the form of a single number for the year in a manner similar to the condensing process in Gagne‟s Goal Based Illuminance calculation [21]. As with the energy efficiency calculations, the ECD metric will be reported as a comparison to the base case window scenario. This provides a physical reference for how a complex fenestration is performing relative to a standard and intuitive alternative. Temporal maps are a visual means to represent data for an entire year. Horizontally, these images show annual performance and vertically they show performance along the hours of the day indicating when a space is lit comfortably, too little or too much [22]. 2.4. View Clearness The ability to see an accurate image through a window component has been identified as being a critical aspect of performance for its acceptance by occupants [24]. One simple and relevant way to characterize view is to define full, partial, or no view to an occupant inside. View is a function of the light

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that is transmitted directly and without distortion. We propose to define the View Through Potential (VTP) metric as being the percentage of space which receives direct and „undistorted‟ light, thus corresponding to a rough estimation of how much of the space will benefit from various levels of view. Quantitative thresholds for these qualitative definitions are being determined through sampling a larger set of fenestration systems that are correlated with particular levels of view. As before, the metric will ultimately be reported with respect to a clear double-glazed window in order for the user to correlate quantitative values with qualitative experience. In order to determine quantitative values, we use the visible spectrum BTDF data which provides local information about the ratio of visible light transmitted through the surface. We propose a quantitative method to analyze the BTDF of each sample as a comparison to a perfectly clear view. The ratio of the undistorted light to the total amount of light transmitting provides a quantity for how much scattering occurs. Moreover, a hole can be assumed to transmit light with no distortion, and thus has been selected as the reference case (not to be confused with the base case clear double-glazed window). Quantitatively, the BTDF of a “hole” sample – no fenestration surface – indicates how light behaves at each incident condition. The BTDF of each fenestration system can then be compared to the unmodified behavior as represented by the hole BTDF, as shown pictorally in Figure 3.

Figure 3: The quantity of direct undistorted light that reaches each sensor location will be compared for each system (e.g. right) to a “hole” reference case (left).

Each sensor location perceives each point on the window with a unique angle of reference. Figure 4 shows the range in possible view angles for a single sensor location. Each location on the window grid will be associated with unique BTDF ratio for a given sensor location. The average of these will then be the overall ratio associated with that particular sensor location.

this ratio approaches 1, a clear view is achieved and if this ratio approaches 0, no view is achieved. From these qualifications, each sensor location will receive a credit between 0 and 1 if it is provided with no, partial, or full view. Again, the total credit that a system receives will be compared with the base case clear double-glazed window to provide increased intuition for the user.

3. METHOD FEASIBILTY A requirement to the feasibility of any method, but particularly those relying on parallel ongoing research like ours, is ensuring that the tools or calculation procedures used to produce the desired outcomes are validated to be consistent and accurate. The use of BTDF data in Radiance calculations has been attempted [13] but the inclusion of BTDFs for time-efficient annual simulations is still a work-in-progress [25]. To determine which seems likely to produce the most reliable results in our approach, both methods have been applied for comparison and for a clear window without angular dependence; the processes have been shown to provide equivalent results. 3.1. Base case results Using the methods presented in Section 2, the base case scenario data set was constructed and is presented here to demonstrate the feasibility of the process. Relative Energy Impact The Solar Heat Gain Factor was calculated as a function of angle-dependent transmissivity and local weather conditions for each hour of the year. Using the temporal map form as presented previously, it is possible to view the heat flow due to solar irradiation for each hour in a single graphical representation as in Figure 5, which shows the angle dependence of the solar heat gain factor for a south facing CFS façade in Miami, FL. This graph does not speak to whether the solar heat gain factor is contributing to cooling loads or reducing the heating load but clearly shows the times of the year which a south facing façade receives direct sunlight due to solar angle. Solar Heat Gain Factor (W/m2) Temporal Map

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For each sensor location, the overall ratio of the system‟s BTDF to the value of the hole‟s BTDF will indicate how clearly an occupant can see outside. If

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Figure 5: Temporal map of Solar Heat Gain Factor in Watts per square meter of façade area for a sample CFS.

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Similarly, the hourly resistance heat flow across the façade can be calculated as a function of weather conditions. As is clear in Figure 6, there is little variation over the course of each day in amount of heat flow across the system although it does vary with season.

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Figure 6: Temporal map of Resistance Heat Flow in Watts per square meter of façade area for a sample CFS.

Combined, the data represented by Figures 5 and 6 show the total amount of heat transfer that occurs for the space as a result of the fenestration system. The net heat flow is described pictorially in Figure 7. When there is no sunlight (at night), the heat flow across the façade dominates, resulting in near or slightly below zero heat passage. Meanwhile, direct solar irradiation results in substantial heat gains. 24

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Occupant Visual Comfort While the ECD metric is a single value that represents the visual comfort performance over the year, Figure 8 shows more explicitly the profile of performance of two different façades, also in Miami, FL. For each moment of the year, the space achieves a certain value that can be represented as a percentage of sensors that achieve comfortable light conditions. Using the 56 representative moments [23], it is possible to quantitatively assess the relationship between the amount of time that achieve “comfortable conditions” as the requirement for the fraction of space that is comfortably lit the amount of time the room achieves those conditions decreases.

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Figure 8: Percentage of time and space that achieves comfortable light levels according to the ECD metric for the base case (top) and a sample CFS (bottom).

View Clearness Finally, the VTP metric was also calculated for the clear double-glazed window base case façade. Because the view range is within 60 degrees of normal incidence, this glazing does not exhibit any angle-dependent properties. (For a standard window, view angles greater than 60 degrees do result in a decrease in transmittance and an increase in reflectance.) As such, the VTP is equal to the façade‟s overall transmissivity of 82%. This façade is characterized as providing a clear view to the outside. The sample CFS is considered to provide no view to the outside and its VTP value is 8%.

4. CONCLUSION The method proposed is the first step toward creating a comprehensive and robust set of metrics that inform the user about the technical performance of a complex fenestration system. Once the method feasibility validation has been completed, detailed technical data can be computed. Following, a phase of data analysis will identify the critical aspects of fenestration technology in actual implementation through rigorous sensitivity analyses. Being able to isolate the variables to which performance is most sensitive will enable us to condense the data into more readable forms and ultimately generate a relevant rating system. The goal of this research is to promote utilization of complex fenestration systems to improve building energy performance by disseminating technical information in a form that is easily understandable, thereby generating demand for an energy-efficient product. By providing a standard on which manufacturers can compete, this will also stimulate innovation in a typically slow-moving industry. With improved communication, designers and engineers

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can engage in integrated design processes that will contribute to a transformed building industry that is mindful of the importance of energy efficient technologies and objectives.

5. ACKNOWLEDGEMENTS Shreya Dave was supported in this research effort by an MIT Energy Initiative Seed Grant. Marilyne Andersen received support through MIT and EPFL. In addition, a number of people were instrumental in the brainstorming and implementation of the method; the authors thank Anne Iverson, Mike Rubin, Greg Ward and Jaime Gagne for being resources in the development of these concepts.

6. REFERENCES [1] Environmental Information Administration (2008). EIA Annual Energy Outlook. [2] Arasteh, D., Apte, J., Huang, Y.J. “Future Advanced Windows for Zero-Energy Homes”, ASHRAE Transactions, Vol 109 Part 2 (2003). [3] Commission Internationale de l‟Eclairage (CIE). “Radiometric and photometric characteristics of materials and their measurements”. CIE 38 (TC2.3). (1977). [4] Klems, J.H., Warner, J.L. Kelley, G.O., “A comparison between calculated and measured SHGC for complex glazing systems. ASHRAE Transactions, Vol 102 Part 1 (1997). [5] National Fenestration Rating Council. Accessed 14 October 2010. [6] IES Lighting Handbook, 8th Edition. IES of North America, (1993). [7] Rienhart, C.F. “Tutorial on the use of daysim simulations for sustainable design,” Institute for Research in Contstruction, National Research Council Canada, (2006). [8] Association Suisse des Electriciens, Eclairage interieur par la lumiere du jour, Zurich, (1989). [9] Nabil, A., Mardaljevic, J. Useful daylight illuminances: A replacement for daylight factors. Energy and Buildings 38, pp. 905-913 (2006). [10] Wienold, J., Christoffersen, J. “Evaluation methods and development of a new glare prediction model for daylight environments with the use of CCD cameras.” Energy and Buildings 38 (2006). [11] Wienold J. “Dynamic daylight glare evaluation.” th Proceedings of the 11 International IBPSA Conference, Glasgow, July 27-30, pp. 944-951, (2009). [12] U.S. Climate Zones. United States Energy Information Administration. Accessed 25 January 2010. . [13] Konstantoglou, M., Jonsson, J.C., Lee, E. “Simulating Complex Window Systems using BSDF Data.” 26th Conference on Passive and Low Energy architecture. (2009).

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[14] U-Factors for Various fenestration Products in 2 W/(m K). ASHRAE Handbook – Fundamentals (2005). [15] “Reference Buildings by Building Type.” Commercial Building Initiative Database. United States Department of Energy – Energy Efficiency and Renewable Energy. < http://www1.eere.energy.gov/buildings/commerci al_initiative/new_construction.html> Accessed 14 October 2010. [16] American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and Illuminating Engineering Society of North America (IESNA). “ASHRAE Standard Energy Standard for Buildings Except Low-Rise Residential Buildings.” (1999). [17] Hay, J. E., McKay, D. C. “Estimating Solar Irradiance on Inclined Surfaces: A Review and Assessment of Methodologies.” International Journal of Sustainable Energy. Vol 3, No 4. 203-240. (1985). [18] WINDOW 6.1/THERM 6.1 Research Version User Manual. Lawrence Berkeley National Labs. (2006). [19] Wilcox, S. and W. Marion. User's Manual for TMY3 Data Sets, NREL/TP-581-43156. April 2008. Golden, Colorado: National Renewable Energy Laboratory, (2008). [20] Karlsson, J., Karlsson, A., Roos, A. “A simple model for assessing the energy performance of windows.” Energy and Buildings 33 (2001). [21] Gagne, J., and Andersen, M. A Generative Facade Design Method Based on Daylighting Performance Goals. Journal of Building Performance Simulation (forthcoming). [22] Kleindienst, S., Bodart, M., Andersen, M., “Graphical Representation of Climate-Based Daylight Performance to Support Architectural Design. LEUKOS - The Journal of the Illuminating Engineering Society of North America Vol 5 No. 1, pp. 39-61, (2008). [23] Andersen, M., Kleindienst, S., Gagne, J. Lightsolve Tutorial. Department of Architecture, Building Technology Program. Massachusetts Institute of Technology (2010). [24] Laouadi, A., Parekh, A. “Complex fenestration systems: toward product ratings for indoor environment quality.” Lighting Research Technology Vol. 39 No. 2 (2007). [25] Saxena, M., Ward, G., Perry, T., Heschong, L., Higa, R. “Dynamic radiance – predicting annual daylighting with variable fenestration optics using BSDFs” SimBuild – forthcoming. (2010).

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Balancing the Energy Savings and Daylighting Performance of External Perforated Solar Screens Evaluation of Screen Opening Proportions Ahmed SHERIF1, Hanan SABRY2, Abbas EL-ZAFARANY3, Rasha ARAFA1, Tarek RAKHA1 1 AND Mohamed ANEES 1

Department of Construction and Architectural Engineering, The American University in Cairo, Cairo, Egypt 2 Department of Architecture, Faculty of Engineering, Ain Shams University, Cairo, Egypt 3 Department of Urban Design, Faculty of Urban and Regional Planning, Cairo University, Cairo, Egypt

ABSTRACT: This paper aims at developing new types of external perforated solar screens by balancing between energy efficiency and daylighting. Three objectives were targeted: First, evaluating the energy saving potential of using solar screens in different geographic locations. Second: Examining the influence of screen opening proportions on illuminance values. Third, investigating recommended screen opening proportions for daylighting and their effect on energy efficiency. Two simulation software packages were used for the assessment: Energy Plus for energy performance and Radiance for daylighting performance. Results demonstrated the usefulness of utilizing external perforated solar screens in front of windows. The screens reduced energy consumption by 25% to 35% in a number of cities that lie between 14˚N and 40˚N. Their effectiveness was less obvious in cities that were further north. Daylighting performance investigations in a chosen geographic location (30˚N) suggested that changing the screen opening proportion (horizontal: vertical) from 1:1 to 18:1 efficiently enhanced daylighting. Changing the proportion to 18:1 was recommended as it improved the deficient daylighting behaviour of the North direction, while resulting in a marginal effect on energy consumption. The 1:1 proportion was recommended for the Southern orientation. As for the East and West orientations, it is up to the designer whether the improvement of daylighting due to change in opening proportion is worth the compromise in energy consumption. Keywords: Energy efficiency, Daylighting performance, Solar Screen, Desert Environment, Egypt.

1. INTRODUCTION In hot desert environments, solar radiation passing through windows contributes significantly to cooling loads and energy consumption of buildings. Shading of windows reduces such loads. However, this might compromise the availability of natural light. One of the shading systems used to diffuse daylight and reduce solar radiation indoors is a Solar Screen, which is an external perforated panel that is fixed in front of a window. It resembles a traditional solution named “Mashrabeya”, which is described as a wooden lattice of cylinders connected with spherical joints (Fig.1).

Figure 1: Exterior detail, Mashrabeya bay window by emoonstone – 2007.

The paper builds on previous publications by the authors that addressed the energy and daylighting

performance of perforated wooden solar screens. In a previous publication [1], the authors demonstrated that perforated solar screens were effective in achieving significant energy savings in hot desert climates. The energy performance of the screens was investigated by using Energy Plus simulation software. The highest saving potential was found in Solar Screens with 80 to 90% perforation. This research continued through investigating different screen depths. Highest energy savings reached 30, 30, 25 and 7% in comparison with windows without screens for West, South, East and North orientations respectively. Depth to perforation ratio 0.75 / 0.75 achieved the highest and most significant savings with 80% perforation in West and North orientations and 90% perforation in East and South orientations. In other publications [2 and 3], the authors addressed the daylighting performance of the perforated wooden solar screens. Minimum and maximum perforation percentages were recommended for daylighting purposes. A tool that could be used by architects for design of solar screens that effectively achieve functional needs, while maintaining visual comfort was provided. This was accomplished by performing a series of experiments using Radiance simulation software, where different screen perforation percentages were applied, and daylighting performance was analyzed. This was studied in terms of adequacy through illuminance levels and comfort through glare analysis for a designed living room.

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A number of related publications also addressed the performance of solar screens in regards to daylighting and energy performance. A publication by Aljofi examined the potentiality of reflected sunlight through “Rawshan” screens [4]. Lee and Selkowitz evaluated the performance of two daylighting control systems installed in separate areas of an open plan office, where automated roller shades were installed and controlled to block direct sun [5]. Irregular screen types, such as thermal louvers and vine screens, were previously investigated. Cool or warm water was circulated through the louvers, absorbing or radiating sensible heat. It was suggested that it would be used as a multi function tool that reduces overall annual energy consumption [6]. A vertical vine sunscreen and its passive cooling effect as a solar control technique by plants was also examined. A comparative experiment was conducted on verandas with and without the vine screens [7]. Other research work addressed issues of control [8], user’s response [9], and geometry and tilt angle of venetian blinds [10]. Reviewed literature demonstrates that solar screens investigations did not address the balance between energy performance in different geographic locations and its relationship to daylighting. Configuring Solar Screen parameters that provide acceptable daylighting levels, while controlling thermal comfort and achieving energy efficiency, could pave the way for their utilization in an effective manner that does not only build on historical precedents, but also achieves performance goals of today’s modern buildings.

2. OBJECTIVES AND METHODOLOGY This paper aims at the development of modern external perforated solar screens. The objectives of this paper and their investigation methodology are represented in following three phases:

Table 1: Architectural parameters for the tested space. Indoor Space Parameters Floor level Zero level Dimensions 4.20 m * 5.40 m * 3.30 m Wall Thickness 0.35 m Window Parameters Dimensions 2.30 m * 1.20 m Visual Lighting Transmission 85%

3. PHASE I: ENERGY SAVINGS IN DIFFERENT GEOGRAPHIC LOCATIONS The focus of the simulation process of this phase was to evaluate the energy demand resulting from the cooling, heating and artificial lighting loads of the modelled space. A “dwelling lounge” with a directexpansion, split-type, air-conditioning system was modelled. The base case was opening-tuned to focus on the thermal effect of using the tested screens. The floor, roof and three of the room walls were assumed adiabatic. The fourth wall had a double glazed window at its centre where the solar screen was attached. This wall was modelled as a brick cavity wall covered with plaster on both sides. Different cases of external perforated solar screens were applied in front of the window of the base case. Tested screen perforation percentages were 80% and 90%. The screen openings were square shaped and their depth ratios (opening height / opening depth) ranged from 0.25 to 2 in different window orientations during all seasons (Fig. 2). Monthly and annual simulation runs were conducted for the main four orientations using the weather files of a number of cities located in the latitude range of 14˚N - 60˚N. Simulation results of each of the simulated cases were compared with those of their “no screen” base cases (zero depth ratio).

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Phase I: Evaluating the energy saving potential of using solar screens in different geographic locations, and identifying locations that receive highest savings due to their shading effect. A computer model was created by the use of two computer simulation programs, Design Builder and Energy Plus 3.1. Phase II: Examining the influence of screen opening proportions as one of the parameters that aid in the effective utilization of solar screens in daylighting. Experimentation was conducted using simulation software Radiance. Phase III: Integrating results of Phase I and Phase II. This results in a solar screen design that balances between energy efficiency and visual comfort.

2.2. Base case parameters A typical indoor space with a number of assumed fixed parameters was used as a base case for experimentation. The architectural parameters were chosen to represent the principal features of a typical residential living room (Table 1).

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Figure 2: Geometrical Effect of Changing Solar Screen Depth Ratio.

3.1. Energy performance results The following is a summary of the annual energy loads resulting from changing the screen depth for the screen case having 80% perforation percentage. Results were analyzed for two geographic location types: high and low temperature. Analysis figures emphasize the 0.75 and 1 depth ratios, as they were identified as efficient for energy consumption needs. In the high temperature locations, such as the city of Jeddah 21˚N-39˚E (Fig. 3), the energy consumption is generally inversely proportional to the increase of screen depth. The lowest energy consumption was found in the range of depths between 0.75 and 1.25. As depth increased, window transmitted solar energy decreased with considerable rates till it reached the 0.5 depth ratio, where it decreased with lower rates afterwards. However, the lighting electricity is almost constant till depth 1.5, where it slightly increased.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Cooling loads significantly decreased with the increase of depth till a depth of 0.5. It slightly increased after depth 1.5 till depth 2 due to the increase in lighting loads.

Dakar (14˚N), Jeddah (21˚N), Kharga (25˚N), Taiwan (25˚N), Kuwait (29˚N), Damascus (33˚N) and Cairo (30˚N) respectively. In the cooling dominated climates, the use of screens reduced energy consumption by 29% in Barcelona (41˚N), 7% in Paris (49˚N) and 3% in Oslo (60˚N) (Fig. 6). In the North orientation, the savings could barely be recognized due to limited direct solar penetration.

Figure 3: Annual Energy Loads for a South Oriented Solar Screen with an 80% Perforation, Jeddah (21˚N-39˚E).

Figure 5: Energy Savings of a South Oriented Screen with an 80% Perforation at Different Geographical Locations West Orientation

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In low temperature climates, such as the city of Paris 48°N - 2°E (Fig. 4), the lowest energy consumption was found in depths ranging from 0.5 to 1.25. Lighting electricity was directly proportional to depth, especially after depth 0.5. Cooling loads decreased with the increase in depth till it reached depth 0.5, and then it became constant. Conversely, heating loads increased significantly with the increase in depth till depth 0.5, and then it stabilized. This is due to the increase in lighting loads, which generated heating loads that led to a decrease in the need for heating energy.

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Figure6: Maximum Energy Savings of a West Oriented Screen Having an 80% - 90% Perforation at Different Geographical Locations Figure 4: Annual Energy Loads for a South Oriented Solar Screen with an 80% Perforation, Paris (48°N - 2°E).

The energy savings resulting from using the screens in front of windows at different geographic locations was examined. Fig. 5 illustrates the energy savings due to utilizing an 80% perforated Solar Screen in the South orientation at different geographic locations. Different depth ratios were examined in search for the most promising energy savings. In the South orientation, savings reached 32, 34, 30, 26, 27 and 27% of total energy consumption in the cities of Dakar (14˚N), Jeddah (21˚N), Kharga (25˚N), Taiwan (25˚N), Kuwait (29˚N) and Damascus (33˚N) respectively. The use of screens reduced the energy consumption by 28% in the city of Barcelona (41˚N). On the other hand, limited savings were accomplished in Paris (49˚N) where it became almost 8%. Also, savings diminished to 3% in Oslo (60˚N). In the West orientation, the highest savings were found. These reached 38, 33, 30, 26, 27, 27 and 34 % of the total energy consumption in the cities of

3.2. Energy performance discussion In most locations, depth to perforation ratio 1/1 and 0.75/0.75 achieved considerable savings with 80% and 90% perforation percentages in the West and South orientations. In addition, the effect of depth/perforation configuration on energy consumption proved to be an important factor. It was found that while certain configurations reduced energy consumption; other configurations increase the energy consumption in some of the locations.

4. PHASE II: SCREEN OPENING PROPORTION AND DAYLIGHTING PERFORMANCE In this phase, the impact of the solar screen opening proportions on the daylighting performance was evaluated. The purpose was to explore their potential for performance enhancement, as daylighting has dynamic unique features that create visual richness and a productive atmosphere. Moreover, the utilization of solar screens diffuses natural light. This is important in the clear sky conditions of the desert

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environments. Consequently, an example clear sky condition location was chosen for daylighting simulation (El Sadat City, 30.2˚N - 30.2˚E), Certain parameters of the base case were adjusted due to their contribution to daylighting performance. They include increase of wall and ceiling reflectance to 85.7% (white colour paint) and addition of a solar screen with a perforated top sun-breaker. The solar screen dimensions and depth ratio were based on results of Phase I to be equal to 0.75/0.75 with perforation percentage 90%. Simulation results were tabulated according to different orientations of the window on which the solar screen was fixed (N, E, S, W) and different seasons (spring, summer, autumn and winter) with different times (9:00, 12:00, and 15:00). Research methodology was twofold; the base case was evaluated according to illuminance adequacy (≥200Lux) and daylighting performance was enhanced through change of the screen’s opening proportion (Fig. 7).

daylighting performance was found adequate in almost all seasons and at all three tested zones, except for summer at the mid and far zone at 9:00 and 15:00. However, in the North orientation, there was a significant decrease in illuminance values. Consequently, daylighting performance was found inadequate in almost all seasons in the mid-length and far zones. Conversely, the near zone was adequate in all the tests except for the winter season, On the other hand, in the East and West orientations, change in daylighting performance was considerably affected by the time of the day. For screens oriented towards East at 9:00 and West at 15:00, illuminance values were found adequate in most cases. However, at 12:00 only the near zone met minimum illuminance requirements in all seasons. All other cases were found inadequate. As a general result, the mid-length and far zones were defined as problematic. Further research, thus, focused on their enhancement.

South 800

1:1

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Figure7: Geometric Effect of Changing Screen Proportions: “Horizontal : Vertical” Dimension Ratio

Three zones were analyzed in the base case. The first zone is located near the window: the “near zone”, second zone at mid length of the indoor space: the “mid-length zone” and third zone is near the rear wall: “the far zone”. Each zone contained 84 measuring points in a grid of 0.3m *0.3m at a working plane of height 1 m (Fig. 8). The average of each zone was calculated, excluding the values of direct sun penetration points that were having illuminance levels higher than 5000 Lux.

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Figure 9: Base case evaluation at the three tested zones in different seasons and time ( ≤200 Lux = Inadequacy)

4.1. Daylighting performance simulation results

Figure 8: Phase II base case parameters.

Depending on the time of day and the season, each orientation had a different daylighting performance (Fig. 9). In the south orientation,

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The base case solar screen dimensions, perforation percentage and depth ratio were kept constant. Opening proportions were increased in the horizontal and vertical directions to be 1:3, 1:6, 1:12, and 1:18. A comparative analytical study was drawn in reference to the base case. The aim was to test the usefulness of changing the proportion in either direction on illuminance levels. As a general observation, the illuminance levels were directly proportional to the increase of opening proportion in both directions. For example, when the

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

constant as compared to 1:12. To verify if the observed reduction forms a trend, an extreme case of 1:32 ratio was tested. Results showed that performance either decreased or remained constant in comparison with-the 1:18 ratio (Fig. 13 & 14). South Autumn - 12:00 Noon 1200 1000

50%

45%

Illuminance (Lux)

Percent Increase from Base Case

opening proportions were tripled in the horizontal and vertical directions, the daylighting performance increased in all tested zones of all orientations, seasons and times. In the near and mid-length zones, all illuminance values increased by at an average rate ofTripling 23.5% in reference to the base case, Fin Proportion while the far zone(South increased 18% (Fig. 10). - FarbyZone) 40% 35% 30% 25% 20% 15%

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Near Levels Mid-length Far from Changing Figure 13: Illuminance Resulting Opening Proportion at 12:00 Noon in Autumn North - Summer - 12:00 Noon at South.

Vertical

1200 1000 Illuminance (Lux)

A comparative analysis of daylighting performance in terms of adequacy was undertaken for all tested cases. Analysis of improvement was based on the percentage of cases that became adequate after applying a change in opening proportion. Special attention was given to the midlength and far zones due to their identification as inadequateNorth in most of the baseZone cases - Mid-length - H(Fig. : V 11 & 12).

800 600 400 200

0 Base Case

3: 1

6: 1

12 : 1

18: 1

32 : 1

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600

Near

Mid-length

Far

Figure 14: Illuminance Levels Resulting from Changing Opening Proportion at 12:00 Noon in Summer at North.

500

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1 : 12 H: V

Figure 10: Effect of Changing Opening Proportion to 1:3 on the Illuminance Levels of the Far Zone in South Orientation.

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4.2. Daylighting performance discussion Base Case

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Figure 11: Effect of Changing Opening Proportion on the Illuminance Levels of Mid-Length East - Far ZoneZone - H :inVNorth Orientation. 600

In all orientations, the different opening proportions achieved comparable improvements in daylighting performance. However, it was found that the 1:18 ratio in the horizontal direction had the most positive impact in terms of adequacy and relative illuminance values. Table 2 compares improvement percentages of each orientation in all tested zones. Table 2: Percent Improvement Due to Changing Screen Opening Proportions. Orientations

500 Illuminance (Lux)

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15

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Figure 12: Effect of Changing Opening Proportion on the Illuminance Levels of Far Zone in East Orientation.

An increasing trend in performance was observed until the 1:12 ratio was reached. However in the 1:18 ratio, performance increased, decreased or remained

South

Zones Near Mid Far Near Mid Far Near Mid Far

Base Case 75% 8% 0% 83% 42% 33% 100% 83% 75%

H:V 18:1 100% 42% 8% 100% 58% 42% 100% 92% 83%

Total Improvement 22%

14%

6%

The percentage of adequate cases increased in the mid-length and far zone when the square proportions of the opening were changed in ratio to become rectangle-like. This is because the screen openings started to resemble light louvers that reflect daylight deep into the space. This effect was exploited till the ratio increased more than 1:18.

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5. PHASE III: POTENTIAL OF ENERGY SAVINGS THROUGH RECOMMENDED SCREEN OPENING PROPORTION

when selecting and designing solar screens. Further research is directed towards exploring other screen configurations and their efficient combinations.

In this phase, the overall energy performance of the screen proportion that resulted from phase II analysis (18:1) was tested. Cases with 1:1 and 18:1 opening ratio screens were compared with a no screen window. The same architectural parameters of the base case of Phase II were used. Energy savings through use of 1:1 solar screen reached 17, 15, 14 and 4% in West, East, South and North orientations respectively in comparison with the window without screen. However, savings through utilization of 18:1 solar screen configuration were only 8, 7, 9 and 1% respectively in comparison with the window without screen (Fig. 15).

7. ACKNOWLEDGEMENTS

3500 3000

KWH

2500 2000 1500 1000 500 0 West

East

South

North

Orientation H:V= 1:1

H:V= 18:1

Without Screen

Figure 15: Comparison of Energy Consumption.

6. DISCUSSION AND CONCLUSION The usefulness of utilizing external perforated solar screens in front of windows was demonstrated. The screens reduced energy consumption by 25% to 35% in a number of cities that lie between 14˚N and 40˚N. Their impact was less obvious in cities that were further north. The depth to perforation ratios of 1/1 and 0.75/0.75 achieved considerable savings in most locations with 80% and 90% perforation percentages in the West and South orientations. An in-depth investigation of the above configurations’ daylighting performance suggested that changing screen opening proportions (horizontal: vertical) from 1:1 to 18:1 would effectively improve daylighting. The energy behaviour of the suggested screen opening proportion was tested. Changing the opening proportion to 18:1 improved the deficient daylighting behaviour of the North direction, while resulting in a marginal effect on energy consumption. It is, then, recommended. On the other hand, the 1:1 proportion is recommended in the Sothern orientation, since use of the 18:1 proportion increased the energy consumption by 5.6%. This was not justified especially that the daylighting performance was almost satisfactory in the 1:1 proportion. As for the East and West orientations, it is up to the designer whether the improvement of daylighting due to change in opening proportion is worth the compromise in energy consumption, which ranges between 9-10%. A satisfactory balance between achieving efficient energy savings and daylighting performance within an indoor space constitutes the real challenge

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This publication is based on work supported by Award No. C0015, made by King Abdullah University of Science and Technology (KAUST).

8. REFERENCES [1] Sherif, A., Faggal, A., Arafa, R., 2010, “External Perforated Solar Screens For Thermal Control In Desert Environments: The Effect Of Perforation Percentage On Energy Loads”, Renewable Energy 2010, Joint with 4th International Solar Energy Society Conference, Asia Pacific Region, 27 June- 2 July 2010, Yokohama, Japan. [2] Sherif, A., Sabry, H. and Rakha, T., 2010, “Daylighting For Privacy: Evaluating External Perforated Solar Screens In Desert Clear Sky Conditions”, Renewable Energy 2010, Joint with 4th International Solar Energy Society Conference, Asia Pacific Region, 27 June - 2 July 2010, Yokohama, Japan. [3] Sherif, A., Sabry, H. and Rakha, T., 2010, “External Perforated Solar Screens for Daylighting in Residential Desert Buildings: Identification of Minimum and Maximum Perforation Percentages”, Solar Energy, submitted in August 2010. [4] Aljofi, E., 2005, “The Potentiality of Reflected Sunlight Through Rawshan Screens”, Proceedings from the International Conference: Passive and Low Energy Cooling for the Built Environment, Santorini, Greece. [5] Lee, E. and Selkowitz, S., 2006, “The New York Times Headquarters Daylighting Mock-up: Monitored Performance of the Daylighting Control System”, Energy and Buildings, vol. 38, pp. 914-929. [6] Hoyano A., 1985, “Solar Control by Vine Sunscreen and its Passive Cooling Effects,” Proceedings of the International Symposium on Thermal Application of Solar Energy, Hakone, Japan. [7] Meckler G., 1979, “Energy integrated building envelopes,” Specifying Engineer, Vol. 41 (1), pp. 54-60. [8] Lindelöf, D., 2009, “A fast daylight model suitable for embedded controllers”, Solar Energy, vol. 83, pp. 57 – 68. [9] Sutter, Y., Dumortier, D., and Fontoynont, M., 2006, “The use of shading systems in VDU task offices: A pilot study”, Energy and Buildings, vol. 28, pp. 780 – 789. [10] Tzempelikos, A., 2008, “The impact of venetian blind geometry and tilt angle on view, direct light transmission and interior illuminance”, Solar Energy, vol. 82, pp.1172 – 1191.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The Performance Evaluation of an Advanced Daylighting System in Multi-story Office Buildings: Measurement and Simulation Jianxin Hu1*,, Jiangtao Du2, Wayne Place1 1

College of Design, School of Architecture, North Carolina State University, Raleigh, USA 2 School of Architecture, University of Sheffield, Sheffield, UK * Corresponding author. Tel: +10 919-4234955, Fax: +10 919-5158951, E-mail: [email protected] ABSTRACT: This study investigates the climate-based performance of a lightshelf system in the context of multistory office buildings, which is regarded as one of the most important strategies for achieving the comfortable daylit environment in areas with a highly luminous climate. Computer simulations by DAYSIM are performed to predict annual light quantities in the daylit zones. The DAYSIM results are also compared to several simplified experimental methods, in which the systems are tested under diffuse skies only. These methods use either Daylight Factor (DF) or Coefficient of Utilization (CU) as the performance indicator. The findings show that certain simplified experimental methods, especially the ones based on CU, can be reasonably accurate for climate-based assessments of sidelighting systems in a daylight climate similar to Raleigh, North Carolina. Keywords: daylighting, lightshelf, DAYSIM, daylight factor, coefficient of utilization

1. INTRODUCTION Understanding daylight from a climate-based point of view differs greatly from the traditional approach of the Daylight Factor method, which only addresses overcast conditions and leaves out important design factors, such as building orientation [1]. Consequently, it would be more practical to assess daylighting systems in areas with a highly luminous climate by a climate-based method, in which case various types of sky conditions (e.g. clear sky or intermediate sky) are all taken into considerations. As a dynamic Radiance-based simulation tool, DAYSIM is capable of carrying out Climate-based Daylight Modelling (CBDM) using meteorological dataset [1, 2, 3]. By the comparisons with measurements, it has been proven to be accurate for performing annual daylight predictions [2]. Conducting climate-based daylighting research by physical experiments can be time consuming. Monitoring design options in a full year is normally not feasible for most research projects. Simplified methods are thus adopted by testing the systems on a heliodon so that a limited number of sky conditions can be simulated quickly. Based on these limited data, Daylight Factor (DF – the ratio of interior illuminance and exterior unobstructed horizontal illuminance) or Coefficient of Utilization (CU – the ratio of interior illuminance and exterior vertical illuminance) is often developed to establish the correlations between interior illuminances and exterior daylight resources [4]. If exterior daylight recourse data (e.g. hourly sky illuminances on vertical and horizontal planes in a full year) are available at the building site, annual system performances can be assessed by multiplying the exterior daylight levels by the DFs or CUs. Although daylighting designs can be studied and compared by these simplified experimental methods, it has been a challenge to understand their accuracy

and validity when predicting interior daylight levels on a full-year basis. It is thus the intent of this study to answer the following questions: Compared with the results from DAYSIM simulations, how accurate are the simplified experimental methods (e.g. testing systems under diffuse sky conditions only) for assessing annual performances of sidelighting designs, such as a light shelf system, in multi-story office buildings? By using DAYSIM as a benchmark, which one is a more reliable indicator for annual daylight predictions, Daylight Factor or Coefficient of Utilization? This paper is not intended to evaluate the accuracy of DAYSIM, which has already been validated [2]. The goal of the study is to assess the validities of certain simplified experimental methods by using DAYSIM as a benchmark.

2. METHODS 2.1. The context and the lightshelf system In a previous project conducted in North Carolina State University, a lightshelf system was designed and assessed for a multi-story office building (Figure 1) located in Raleigh, North Carolina [5].

Figure 1: NC Wildlife Resources Commission Headquarters

The building, along with the daylighting system, is used as the context for the study. A 6-ft (1.83 M)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

2.3. Experimental testing

lightshelf and a 3-ft (0.92 M) overhang are integrated in the south elevation (Figure 2) and the interior space is divided into six daylit zones The surface reflectances are: ceiling and walls: 90%; floor: 20%; lightshelf top and bottom surfaces: 90%; overhang top and bottom surfaces: 15%; exterior ground reflectance is assumed at 20%; glazing transmittance: 70%. A scale model (scale: 1:6) is established to represent a 30’X40’ (9.14M X 12.19M) portion of the typical office floor in the building. Annual daylight levels in each zone are predicted by both DAYSIM and physical experiments.

A physical scale model was constructed by lightweight materials and placed on a heliodon for outdoor testing (Figure 4).

 

Figure 4: The scale model being tested on a heliodon

 

Where:

 

- Ceiling height = 11’-2” (3.40M) - Light shelf length = 6’-0” (1.83M) - Overhang length = 3’-0” (0.92M) - Top of view glazing: 7’-2” (2.18M) above the floor Figure 2: Section view of the lightshelf system

2.2. DAYSIM simulations Similarly, a virtual model of the building has been built in a CAD tool, which coincided with the physical model. Several typical points studied were placed along the center line of the daylit zones. The weather file of the site (Raleigh-Durham International Airport) was used as a typical climate data for the simulation. With a proper ambient parameter setting, the annual illuminance profile was first calculated by DAYSIM 3.0.

 

  Figure 3: 3D model prepared in Google Sketch-up for DAYSIM simulations

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To simplify the experimental procedures, the model was only tested under diffuse skies – mostly cloudy sky and blue sky (clear sky without the sun component) for the following reasons: - A diffuse sky is a much more reliable light source than the sun. Sunlight is highly variable depending on seasons, solar angles and weather conditions. - Mostly cloudy sky represents the marginal condition in terms of daylight availability. Testing systems under mostly cloudy skies is thus crucial for predicting daylight autonomy (the amount of time expected to reach a certain light level through the use of daylight). - Daylight Factor is defined in the context of a diffuse sky condition. - Testing under diffuse skies is much less time consuming and much more flexible than testing under various solar angles, since the experiments can be conducted at any time of the year, even in winters when the full range of sun angles cannot be achieved. To be consistent with the DAYSIM model, a LICOR photocell sensor (Model 210L) was installed at the center of each daylit zone (Sensor Ez1 through Ez6). An exterior sensor (Ev) was mounted on a vertical plane facing the same direction as does the window. Two additional exterior sensors were placed horizontally to measure global (Eg) and diffuse (Ed, with a shadow band) illuminances. The model was first tested under blue sky condition. To simulate a blue sky condition on a clear day, the system designed for facing south was rotated so that it faced only diffuse sky (Figure 5). This approach allows for the system to be tested only under diffuse blue sky by eliminating the sun component. A DF and a CU can then be developed for each zone to establish the relationship between the sky and interior illuminances. Using Zone 1 as an example, the DF and CU are calculated by the following formulas: DF1 = Ez1 / Ed CU1 = Ez1 / Ev

 

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Shadow-banded horizontal sky illuminance (Ed) is used in this case to calculate the Daylight Factor, since diffuse sky light is the only light source for the system.

 

3. DATA ANALYSIS 3.1. Calculating DFs and CUs Illuminance values measured by the interior and exterior sensors under both blue sky and mostly cloudy conditions are displayed in Table 1. A DF and a CU are then calculated for each of the six interior daylit zones (Table 1). Table 1: Interior & sky illuminances and calculations of DFs and CUs

 

Figure 5: Model being tested under blue sky. (The lightshelf system is designed for south-facing. However, it is rotated in the experiment to face away from the sun, towards diffuse sky light only)

The model was also tested on a mostly cloudy day (Figure 6). Similarly, a DF and a CU can be obtained for each zone under this sky condition. Again, using Zone 1 as an example, the DF and CU are calculated by: DF1 = Ez1 / Eg CU1 = Ez1 / Ev Note that global horizontal sky illuminance (Eg) is used for calculating the DF, because the sun component has little contribution under a mostly cloudy sky. In fact the global and shadow-banded horizontal measurements are very close in this case.

 

 

 

All illuminance data were stored in a Campbell Scientific CR1000 data logger and then collected by a laptop computer (Figure 7).

 

Figure 7: Instrumentation panel mounted on heliodon for storing and collecting illuminance data

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3.2. Predicting annual daylight quantities

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Figure 6: Model being tested under mostly cloudy sky

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By multiplying the CUs or DFs by the annual exterior illuminance data (Ev, Eg, or Ed), hourly daylight levels in all six zones can be predicted in a full year. Based this strategy, six methods can be developed: 1. CU based on blue sky 2. CU based on mostly cloudy sky 3. Averaged CU based on both blue sky and mostly cloudy sky 4. DF based on blue sky 5. DF based on mostly cloudy sky 6. Averaged DF based on both blue sky and mostly cloudy sky The annual exterior illuminance data were made available by the Daylighting Research Lab at NC State University. The data set, including hourly Ev, Eg, and Ed values in a full year (from 5:00am to 7:00pm, solar time), was collected in a two-year period (1991 & 1992) in Raleigh, North Carolina [6]. Table 2 shows the process of using Method 1 (CU based on blue sky) to predict hourly illuminances (Lux) in daylit zones by incorporating south-facing Ev (Lux) from the annual sky illuminance data set. Table 2 only shows the calculations for the first day of the year. When the full year predictions are completed, the number of hours, during which the predicted illuminances are above a target illuminance level (this study assumes 500 Lux, as recommended by IESNA for general office lighting), are counted in each zone. These numbers can be used to develop

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Daylight Autonomy, which is one of the important indicators for climate-based assessments. Table 2: Using Method 1 (CU based on blue sky) to predict hourly illuminances (Lux) in daylit zones by multiplying CUs with the south-facing vertical sky illuminances (Ev in Lux) from the annual sky illuminance data set.

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Annual performances are then assessed by the rest five methods in a similar fashion, expect that Methods 1, 2 and 3, which are using CU, are based on annual vertical sky illuminances, whereas Methods 4, 5 and 6, which are using DF, are based on annual horizontal sky illuminances.

3.3. Comparing simplified experimental methods with DAYSIM

To estimate how close the results are between DAYSIM and experimental methods, the Sums of Squares of the differences between DAYSIM and each of the experimental methods in all six zones are calculated. For example, the Sum of Squares for Method 1 (CU based on blue sky) is calculated by:

 

Sum of Squares = (3610 – 3824)² + (3348 – 3615)² + (3101 – 3405)² + (2885 – 3044)² + (2699 – 2747)² + (2678 – 2609)² =241847 Table 5 shows the Sums of Squares for all six methods. Table 5: Sums of Squares of the differences between DAYSIM and each experimental method in all six zones

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A smaller Sum of Squares indicates a closer match. Apparently Method 1 – CU based on Blue Sky generates the closest results to DAYSIM. This trend is also illustrated in Figure 8, which visually presents the same information as in Table 3.

 

Predicted by the six experimental methods and by the DAYSIM simulations, the numbers of hours, in which interior illuminances are above 500Lux, are shown in Table 3. The percentage of the differences between DAYSIM and each of the experimental methods are shown in Table 4. Table 3: The numbers of hours in which interior illuminances are above 500Lux predicted by DAYSIM and the six experimental methods

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Table 4: Percentage of differences when comparing results from the experimental methods with those from DAYSIM

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BUILDING PHYSIC (DAYLIGHTING)

  Figure 8: The numbers of hours in which interior illuminances are above 500Lux predicted by DAYSIM and the six experimental methods

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

4. CONCLUSION Although computer-based simulation is increasingly used for daylighting studies, conducting physical experiments is still crucial for this type of research, because light quality and spatial perception can be difficult to assess by computer simulations. A large enough scale model, such as the one used in this study, allows people to assess light quality by observing through the view ports provided on the walls, so that the observer can be immersed in the luminous surround. As mentioned earlier, measuring annual light quantity by physical testing can be difficult, since monitoring a design on a year-around basis is extremely time consuming. However, as proven by this study, if DAYSIM is used as the benchmark, certain simplified experimental methods (testing systems under diffuse skies only) can be reasonably accurate for climate-based light quantity assessments in a daylight climate similar to Raleigh, North Carolina. This is significant and reassuring in that, without solar angles involved, testing systems under diffuse skies can be fairly quick. The system in this study was tested on two days, a clear day and a mostly cloudy day. Of the two groups of experimental methods – CU based and DF based, results show the former generally provides closer predictions to DAYSIM. Especially, Method 1 – “CU based on blue sky” generates the closest match. A CU relates the interior illuminance to exterior vertical illuminance, while a DF relates the interior illuminance to exterior horizontal illuminance. The exterior horizontal illuminance under clear skies only depends on solar altitude, which makes the factor of building orientation out of the question, whereas exterior vertical illuminance under clear skies depends on both solar altitude and azimuth. The exterior vertical illuminance provides a measurement of how much light actually enters the room through wall-based apertures [7]. Vertical illuminance should be a better indicator of lighting conditions outside when assessing sidelighting designs, which are highly dependent upon building orientation. Currently DF is used in LEED as the performance indicator for evaluating all daylighting systems. It is our recommendation to re-evaluate this method of certification.

5. LIMITATIONS & FUTURE RESEARCH There are certainly possibilities for errors in both computational simulations and the physical testing. The divergences might occur at the geometric and photometric characteristics between physical models and computer models [8, 9]. Small errors could be caused by the random nature of the ray tracing process [10] or the sky model generation from solar radiation data. The site for the experiments is generally open, but there are minor blockage of the sky due to the surrounding buildings and vegetation. Useful Daylight Illuminances (UDI) can be a better performance indicator than the Daylight Autonomy method used in this study. UDI is defined as the annual occurrence of illuminances at any given point

on the work plane that are within a range considered “useful” by occupants (e.g. 100 Lux to 2000 Lux). Light levels above 2000 Lux can be a source of discomfort. Therefore, the UDI approach can be a more effective indicator than Daylight Autonomy, since it addresses not only the lower limit but also the upper limit of the useful daylight range. As the next step of this research, it is our proposal to monitor the models of typical sidelighting and toplighting systems for one year and to measure daylight climate data (e.g. sky illuminances and irradiances) simultaneously, so that the concurrent data of the systems and the skies at the same location can provide a solid basis for evaluating any simplified experimental methods and computer simulations on various types of daylighting systems.

6. REFERENCES [1] Mardaljevic, J., “Examples of Climate-Based Daylight Modelling”, CIBSE National Conference 2006: Engineering the Future. [2] Reinhart C F, Walkenhorst O, “Dynamic RADIANCE-based daylight simulations for a fullscale test office with outer venetian blinds.” Energy & Buildings, 33:7 pp. 683-697, 2001. [3] Reinhart C F, Herkel S, “The simulation of annual daylight illuminance distributions – a state-of-theart comparison of six Radiance-based methods.” Energy & Buildings, 32 pp. 167-187, 2000. [4] Brackett, W., “Daylighting Coefficient of Utilization Tables”, 83.038, AD-A134028. Port Hueneme, CA: Naval Civil Engineering Laboratory, 1983. [5] Hu, J., “The design and assessment of advanced daylighting systems integrated with typical interior layouts in multi-story office buildings”, Doctoral Dissertation, North Carolina State University, 2003. [6] Place, W., Howard, T., and S. Howard, “Daylight Resource Data for Illuminating Building Interiors in North Carolina“, North Carolina Alternative Energy Corporation, 1992. [7] Li, D. and J. Lam, “Measurements of Solar Radiation and Illuminance on Vertical Surfaces and Daylighting Implications”, Renewable Energy, 20 pp. 2000. [8] Thanachareonkit, A., Scartezzini, J-L., Andersen, M., "Comparing daylighting performance assessment of buildings in scale models and test modules", Solar energy, 79 pp. 168-182. 2005 [9] Thanachareonkit, A., “Comparing physical and virtual methods for daylight performance modelling including complex fenestration systems“, PhD, EPFL, Switzerland, 2008. [10] Ward, G. L., & Shakespeare, R., Rendering with Radiance: The art and science of lighting visualization. Morgan Kaufmann Publishers, Inc. 1998.

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Investigation of 3D projection for qualitative evaluation of daylit spaces Coralie CAUWERTS1, Magali BODART1 1

Architecture et Climat, Université catholique de Louvain, Louvain-la-Neuve, Belgium

ABSTRACT: This paper presents the results of a study that investigates 3D projection for lighting quality evaluations. Thirty-nine participants forming groups of three visited eight daylit rooms and rated them through seven-grade bipolar scales. During the visit of each room, a series of pictures were taken at different exposure time. Then, they were combined to reconstitute HDR pictures capturing scene luminances. A global tone-mapping operator mimicking the human visual system was then applied to the resulting HDR pictures to compress the range of real world luminances to that of the projector. In the second place, participants rated through the same questionnaire the pictures projected in 2D and in 3D. Finally, they chose which kind of projection was the more realistic. Comparison of subjective ratings issued from the visit of real spaces, and from 2D and 3D projections of these scenes suggests that projected tone-mapped pictures can be used for lighting evaluation of bright scenes. Dim scenes whose luminances are much lower than those available with the projection presented significant differences of scores. In addition, even if some scenes are judged more realistic in 3D than in 2D, subjective ratings are not significantly different according to the kind of projection. Keywords: lighting quality evaluation, HDR imaging, tone mapping, stereoscopy, 3D projection.

1. INTRODUCTION Several studies have demonstrated that pictures could be used as a substitute in lighting evaluation of real spaces. Some worked with 2D projections but did not deal with the question of luminance [1, 2, 3]. Some others considered that it was important to display real luminances [4, 5]. The present study investigated 3D projections in the frame of a research exploring factors influencing luminous quality and visual interest of daylit spaces. Luminance issue is addressed by applying a global tone mapping operator to HDR pictures taken in the real space. This tone mapping aims at reproducing visual impressions similar to those felt in the real space [6]. Three dimensional projections on a large screen are a way to improve realism of the pictures and can help the immersion of the observer in the projected space. In fact, linear perspective, treatment of shadows and atmospheric perspective are already clues helping the human brain to recreate depth in 2D pictures. Stereoscopic pictures (3D pictures), in mimicking natural binocular vision of humans, still increase the illusion of relief in introducing the third dimension on the 2D medium [7]. The aims of the present study were to determine if luminous impressions felt in the real space were well reproduced with projections and if subjective ratings were closer to the reality with 3D projections than with 2D projections.

2. STEREOSCOPIC PRINCIPLE Stereoscopic principle consists in delivering two slightly different pictures to the eyes, mimicking human binocular vision. In this research, polarized projection on a large screen was used to deliver these two different pictures, the large screen helping the

immersion of the observer in the projected space. Pictures were projected superimposed onto the screen, each projector providing a picture for an eye, and polarized glasses ensuring that each eye sees the picture which was designed for it. In 3D projection, perceived depth of an object (A or B) is directly proportional to screen disparity which is the distance (AlAr and BlBr) between two corresponding points of the left and right pictures, projected on the screen (fig.1).

Fig.1: Stereoscopic principle a) A seems behind the screen b) B seems in front of the screen.

In this experiment, the screen disparity was set, for each scene, to produce realistic space.

3. METHOD The experiment was divided in two sessions: the visit of the real spaces and the projection of pictures taken in these spaces. The first part of the experiment took place at the Vinci building of the faculty of Architecture in Louvain-la-Neuve (50°40’N 4°37’E). Participants were invited to visit eight daylit rooms of the building and to rate them through 14 seven-grade bipolar scales. One week later, they evaluated the same spaces projected on a large screen, in 2D and in 3D.

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3.1. Participants Participants were recruited by emails and were not paid. The email explained briefly the purpose of the study without saying any word about 3D projection, to avoid recruiting people with a particular interest in this kind of projection. Thirty-nine participants (20 females), forming groups of three and aged between 20 and 62, took part to the study. Nineteen participants worked or studied in the building. Fifteen were architects or students in architecture. Thirty participants viewed 2D projections before 3D projections. 3.2. Daylit spaces The experiment took place at the end of June and at the end of July. Thirty-eight percents of visits were fixed at noon; other visits took place between 9.00 and 17.00. On average, six days separated the visit of the real space and the day of the projection. Visit of the real spaces took about 30 minutes and the projection, 45 minutes. Visit of the real space always took place before the projection in order to project pictures taken during the visit. 3.2.1. Real spaces Participants, forming groups of three, visited the eight rooms in the same order: lobby, staircase, mezzanine, second floor corridor, Pepermans meeting room, first floor corridor, 2-person office and library. Rooms presented different patterns and levels of luminances. During the visit of each group, a series of low dynamic range (LDR) pictures were taken at different exposure time, in order to recompose high dynamic range (HDR) pictures. Pictures were taken at 160cm from the floor which corresponds to the Belgian average eye height [8]. The camera used in this study is a FUJIFILM FinePix Real 3D W1 and is the first device with double lenses on the market capturing simultaneously two pictures, one for each eye. The angle shots were identical for all the groups. However, in the mezzanine, the position of the camera was modified during the experiment in order to improve 3D pictures. In the office, it is the inclination of the camera which was modify for the same reason. In each room, observers were standing at a fixed position and were asked to look in a particular direction and not to move their head during the rating. In this way, their field of view was as close as possible to those captured by the camera. 3.2.2. Projections Spaces were projected in the same order than the visit. Each group of three participants viewed specifically pictures taken during their visit of the rooms. The projection room (fig.2) was equipped with two LCD projectors (Barco iQ R500) and a polarizing filter. The two projectors were necessary for the 3D projection while only one of the projectors was turned on for the 2D projection. Pictures were projected on a non-depolarizing screen. Black curtains were placed around the screen to favorize the immersion in the picture and to reduce reflections in the room.

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Fig.2: Projection room.

During the projections, observers were standing in order to be in the same position than in the real space. Position of the observer was indicated by marks on the ground and was chosen in order that 3D pictures looked fine and that cast shadows of the observer on the screen were avoided. Luminance correction of projected pictures had been determined according to this position in the room. 3.3. Creation of projected pictures Before their projection, HDR pictures taken during the visit had been processed in order that luminances projected on the screen and viewed through passive glasses were as close as possible to real world luminances captured by HDR imaging techniques. 3.3.1. HDR pictures LDR pictures were combined in HDR pictures capturing real world luminances, according to the method described in [9, 10] and using the hdrgen command-line in Radiance [11]. 3.3.2. Luminance correction Performances of the display device were determined in projecting successively black and white backgrounds with each projector. Luminances on the screen were measured using HDR techniques and a luminance meter. Variation of luminances on the screen, due to the projection technology, was observed. A filter was determined to correct it [12]. This filter reduces luminances in the center of the screen, increases luminances near the border and fixes maximal displayable luminance to 300cd/m². Measured minimum display luminance was equal to 7cd/m². As it was not possible to display the entire range of real world luminances with the chosen technology, HDR pictures were tone-mapped to reduce luminance range in creating pictures reproducing visual impressions felt in the real space. A global tone mapping operator mimicking the human visual system was used to compress the range of real world luminances to that of the projectors [6, 13]. This tone mapping was realized using the Radiance pcond command-line.

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300

Finally, luminances of the picture were overall increased by 15% to counter the wearing of passive glasses.

200

3.4. Measures

100

3.4.1. Luminances HDR pictures, recomposed on the basis of pictures taken in the real space, inform about repartition and level of luminances in the room.

0 cd/m²

Fig.4: Luminances of the 2-person office (a) before and (b) after tone-mapping 300

3.4.2. Illuminances During the visit of each group and for each room, horizontal and vertical illuminances at eye height were measured with a lux meter.

200 100

3.4.3. Subjective evaluation Rooms were rated by each participant through 14 seven-grade bipolar scales. The same questionnaire (fig.3) was distributed for the visit of the real spaces and for each type of projection. The questionnaire contained ten bipolar adjective scales and four questions oriented on the general satisfaction of space and light. The questionnaire was developed on the basis of the work of [14, 15, 16, 17, 18, 19].

0 cd/m²

Fig.5: Luminances of the second floor corridor (a) before and (b) after tone-mapping

4.2. Level of illuminance The second floor corridor is the darkest space. It is followed by the library, the staircase, the mezzanine and the first floor corridor. The Pepermans meeting room, the 2-person office and the lobby present the highest horizontal and vertical illuminances (see fig.6).

Fig.6: Horizontal and vertical illuminances at eye height.

4.3. Frequency histogram of scores

4. RESULTS

The analysis of the frequency of scores of each question (all the rooms together) reveals that two questions (Stimulating/Relaxing and Tense/Relaxed) present a higher frequency of neutral responses. During the visit, some participants said that they had some difficulty to take a decision because they found that the space was neither the first adjective nor the second.

4.1. Luminances

4.4. Mean scores

A global tone-mapping operator adapted luminances of the real scene to the performances of the display devices (see fig.4 and fig.5).

Mean scores of all participants, for each room and each question was calculated for the three different

Fig.3: Questionnaire (translated from French).

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types of presentation (real space, 2D projection and 3D projection). Fish-eye view, projected picture (for left eye) and mean score for each type of presentation are showed in fig.7 and fig.8 for two different spaces: the 2-person office and the second floor corridor.

during the 2D projection and the 3D projection was firstly calculated over all rooms, for each question separately. For the 2D projection, MAE varies between 0.72 (question #9) and 1.48 (question #3) with a mean of 1.11. For the 3D projection, it varies between 0.86 (question #8) and 1.45 (question #3) with a mean of 1.10. MAE was then calculated over all questions, for each room separately. The Pepermans meeting room and the 2-person office present smallest MAE while the second floor and the first floor corridor the highest MAE. Differences between 2D and 3D projections are minor and vary between 0.003 (question #8) and 0.17 (question #9) with a mean of 0.06. 4.6. Analyses of variance

Fig.7: View of the 2-person office and mean scores.

Fig.8: View of the second floor corridor and mean scores.

4.5. Mean absolute error (MAE) The mean absolute error (MAE) between scores given in the real space and respectively those given

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Subjective ratings were analyzed using R software [20]. A series of multivariate and univariate analyses of variance (MANOVA and ANOVA) were conducted to determine if differences of score given in the real space and for each type of projection were significant. Differences are “statistically significant” when p < 0.05(*), “very significant” when p<0.01(**) and “extremely significant” when p<0.001(***). To address the problem of multiple comparisons (ANOVA’s), pvalues were adapted using the Bonferroni correction [21]. A first two-way presentation type x room MANOVA revealed a statistically significant interaction (p=0.018) between the type of projection and the room, suggesting that the room influences the effect of the presentation type. We conducted then a series of 1-way MANOVA, for each room separately, to evaluate for which room differences of scores (real space vs 2D projection, real space vs 3D projection and 2D projection vs 3D projection) were significant. This analysis shows significant differences between scores for the library (real vs 2D: p=0.00329** and real vs 3D: 3.82e-05***), for the second floor corridor (real vs 2D: p=1.078e08***and real vs 3D: 6.722e-07***) and for the staircase (real vs 2D: p=0.001010** and real vs 3D: 0.0003362***). The first floor corridor and the lobby present statistically significant differences between scores given in the real space and the 3D projection. While the Pepermans meeting room presents statistically significant differences between scores given in the real space and those issued from the 2D projection. The 2-person office and the mezzanine do not present significant differences neither between real space and 2D projection nor between real space and 3D projection. The conducted 1-way projection type (2D vs 3D) MANOVA showed that differences between 2D and 3D scores are not significant. A series of 1-way ANOVA’s, for each room separately, was finally conducted to evaluate which question presented significant differences (see Table 1). Question #1 (Bright/Dim), question #3 (Glaring/Not glaring), question #4 (Stimulating/Relaxing), question #12 (Light satisfaction), question #13 (Quality of light) and question #14 (Quantity of light) present very or extremely significant differences. Questions #2

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

(Pleasant/Unpleasant) and questions #11 (Space satisfaction) present statistically significant differences while questions #5 to #10 never present significant differences.

Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Q11 Q12 Q13 Q14

2D 3D 2D 3D 2D 3D 2D 3D 2D 3D 2D 3D 2D 3D 2D 3D 2D 3D 2D 3D 2D 3D 2D 3D 2D 3D 2D 3D

*** *** ** ** *

*

Library

2-person office

1st floor corridor

Pepermans room

2nd floor corridor

Mezzanine

Staircase

Lobby

Real vs.

Question

Table 1: Results of the 1-way presentation type (real vs. 2D and real vs. 3D) ANOVA’s.

*** ***

Room

Lobby Staircase Mezzanine 2nd floor corridor Pepermans room 1st floor corridor 2-person office Library

Number of participants who judged the room more realistic 2D 10 18 12 13 15 11 19 14

3D 22 15 24 20 12 24 15 17

χ²

4.50 * 0.27 4.00 * 1.48 0.33 4.83 * 0.47 0.29

Signif.: *=p<0.05 ; **=p<0.01 ; ***=p<0.001

* *** *** **

5. DISCUSSION **

* *** ** * ** *** ***

Table 2: Results of the Chi-square test

** **

* **

* *

Differences: * Significant ** Very signif. *** Extremely signif.

The second floor corridor and library present significant differences for several questions while staircase present significant differences for the question #3 (Glaring-Not glaring). First floor corridor presents significant differences for questions about general satisfaction of light and space. Lobby, mezzanine, Pepermans meeting room and 2-person office do not present significant differences of scores (real vs. 2D and real vs. 3D).

4.7. Chi-square test Chi-squared test was used to evaluate the realism of 2D and 3D projections. Participants were invited to choose, for each scene, which projection seemed more realistic. Three rooms were significantly judged as more realistic in 3D than in 2D: the first floor corridor, the lobby and the mezzanine (see Table 2).

Our hypothesis was that 3D projections, in increasing realism of the pictures would help the immersion of the observer in the projected picture and reduce differences of subjective ratings between projections and real space. The creation of high quality 3D pictures requires some supplementary adjustments than 2D pictures. Perspective should not be exaggerated but should be sufficient to be perceived and geometric and luminance discordances should be avoided. Before each projection, pictures were visualized to determine the better screen disparity and to correct white pixels appeared at the creation of the picture. Three rooms among eight were judged more realistic in 3D: the first floor corridor, the lobby and the mezzanine. The first floor corridor presented a view framed by a window. This frame was redrawn with the screen of the projection. Lobby and mezzanine were the two larger visited spaces. But even if some rooms are judged more realistic in 3D, analyses showed that there are no significant differences between 2D and 3D projections. First floor corridor, library and staircase are the three darkest rooms visited. They are also the three rooms presenting extremely significant differences of scores between real space and projections. When luminances of the scene were low i.e. inferior to the performances of the display device, tone-mapping increased overall luminance of the picture (see fig. 4 and 5). That is the case for the staircase, the second floor corridor and the library. These three spaces are globally judged more luminous and/or glaring with the projections. The chosen tone-mapping is not adapted to this kind of dark spaces. Moreover the presence of sun rays in the scene increased contrast in tonemapped pictures which seemed more glaring. That means that glare could not be evaluated when contrast in the projected scenes is too high. The mezzanine, the 2-person office and the Pepermans room do not present significant differences of subjective ratings between real space, 2D and 3D projections. The lobby and the first floor corridor present some slight differences. These five rooms are the most luminous visited rooms.

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6. CONCLUSION AND FUTURE WORK This study shows that projected tone-mapped pictures can be a substitute for real space if this one is not too dim. Indeed, subjective ratings in brighter rooms are similar using the projection than in the real space. But, visual impressions felt in dark rooms are not well reproduced with projections of tone-mapped pictures. Projected dark rooms seem brighter than real spaces, and contrasted scenes, more glaring. The chosen global tone-mapped operator and projection technology are not well adapted to lighting evaluation of dark rooms. In addition, this study demonstrated that some scenes are judged more realistic with the 3D projection than with the 2D projection. However, this realism does not influence subjective ratings: differences of rating between 2D and 3D projections are not significant. Experiment will be reiterated with a 3D LCD display (Samsung 2233rz, 1680*1050, 22 inches, 120Hz) which is smaller than the screen in the projection room but which offers a more uniform luminance distribution and higher contrasts. Tonemapping will be adapted to this display and pictures will be rated, by the same participants, in 2D and in 3D.

ACKNOWLEDGMENTS This research was supported by the Belgian Research National Foundation (FNRS). We thank the Communications and Remote Sensing Laboratory (TELE) of the Université catholique de Louvain (UCL) for the access to their projection room and are particularly grateful to Benoît Michel and Rony Darazi for their precious advice in the field of stereoscopy.

REFERENCES [1] Lo W, Steemers K (2009), The art of brightness and darkness: a critical investigation on daylighting quality, Proceedings of the Passive and Low Energy Architecture (PLEA) 2009 Conference, Quebec City - Canada. [2] Oi N (2005), The difference among generations in evaluating interior lighting environment, Journal of Physiological Anthropology and applied Human Science 24, 87-91. [3] Hendrick C, Martyniuk O, Spenser T, Flynn J (1977), Procedures for investigating the effect of light on impression: simulation of a real space by slides, Environment and behavior 9(4), 491-510. [4] Newsham G, Richardson C , Blanchet C, Veitch J (2005), Lighting quality research using rendered images of offices, Lighting Research and Technology 37(2), 93-115. [5] Newsham G, Cetegen D, Veitch J, Whitehead L (2010), Comparing lighting quality evaluations of real scenes with those from high dynamic range and conventional images, ACM Transactions on Applied Perception 7(2), 1-25.

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[6] Larson G W, Rushmeier H, Piatko C (1997), A Visibility Matching Tone Reproduction Operator for High Dynamic Range Scenes, IEEE Transactions on Visualization and Computer Graphics 3(4), 291-306. [7] Sakata H, Tsutsui K, Taira M (2003), Representation of the 3D world in art and in the brain, International Congress Series 1250, 15-35. [8] http://www.dinbelg.be/anthropometry.htm [9] Inanici M (2006), Evaluation of high dynamic range photography as a luminance data acquisition system, Lighting Research and technology 38(2), 123-136. [10] Jacobs A (2007), High Dynamic Range Imaging and its Application in Building Research, Advances in Building Energy Research 1(1), 177202. [11] Radiance software (http://radsite.lbl.gov/) [12] Cauwerts C, Bodart M (2010), Luminance correction of 3D projection pictures for qualitative evaluation of daylit spaces, Proceedings of Illuminating Engineering Society of North America 2010 Annual Conference, Toronto – Canada. [13] Reinhard E, Ward G, Pattanaik S, Debevec P (2005), High Dynamic Range Imaging: Acquisition, Display, and Image-Based Lighting, The Morgan Kaufmann Series in Computer Graphics, 246-252. [14] Flynn JE, Spencer TJ, Martyniuk O, Hendrick C (1973), Interim study of procedures for investigating the effect of light on impression and behavior, Lighting design and application, 16-17. [15] Flynn JE, Spencer TJ, Martyniuk O, Hendrick C (1973), Interim study of procedures for investigating the effect of light on impression and behavior, Journal of the Illuminating Engineering Society 3(1), 87-94. [16] Loe DL, Mansfield KP, Rowlands E (1994), Appearance of lit environment and its relevance in lighting design: experimental study, Lighting Research and Technology 26(3), 119-133. [17] Newsham G, Marchand R, Veitch J (2004), Preferred surface luminances in offices, by evolution, Journal of the illuminating engineering society 33(1), 14-29. [18] Bülow-Hübe H (1994), Subjective reactions to daylight in rooms: effect of using low-emittance coatings on window, Lighting Research and Technology 27(1), 37-44. [19] Dubois MC, Cantin F, Johnsen K (2007), The effect of coated glazing on visual perception: a pilot study using scale models, Lighting Research and Technology 39(3), 283-304. [20] R software (www.r-project.org) [21] Rice W.R. (1989), Analyzing tables of statistical tests, Evolution 43(1), 223-225.

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The potential daylight penetration in deep plan offices Viktoria Lytra Technological Educational Institute (T.E.I.) of Athens, Greece ABSTRACT: This paper investigates the potential daylight penetration in deep plan offices in Northern Europe. The goal of the present work is to define the term daylight ‘passive zone’ in a building and form understanding of parameters that influence the depth of this zone. Initial for this paper was an observation of an architectural office in London, whose lighting performance is not as it should be according to existing literature. Parameters for further study were chosen after checking literature lighting standards. A typical office space has been modelled and simulated using Ecotect and Radiance software respectively while parametric simulations have been undertaken to estimate the impact of different factors, such as window size, external obstruction level and reflectance values, on daylight levels and penetration depth. From all tests it was assumed that the optimum required 300lux for office work reaches in depth approximately the room height at most cases and rarely gets beyond one and a half time the window head height in deep plan offices. Keywords: daylight, passive zone

1. INTRODUCTION The importance of daylighting in architectural design is well known. Generally, it is widely accepted that natural light not only reduces energy costs and enhances visual quality but also improves workers’ performance according to several studies. A typical practical limit for daylight penetration (from side windows) in buildings is approximately 6-9m (rule of Thumb) or equal to two times the window head height [1], given that the space meets some premises given below. The ‘passive zone’ which is created, i.e. the potential passively daylit zone, is defined as the limited area near windows which receives the required light levels 300lux for office work [2]. The lighting performance analysis of a deep plan office was the initial for further study of this rule. It is about an architectural office in Covent Garden in st London, and specifically its 1 floor with an open deep plan (width=12m, length=15m, floor 2 area=192,5m , height = 3,8m). It is almost single lit 2 from east side with a window area of 11,3m and window head height equal to 3,4m. South windows are not taken into account since they are facing a shaft with almost no light. After being monitored with th spot measurements on 17 October 2008, it was observed that illuminance levels from east windows, facing the courtyard, fall off rapidly as somebody moves deeper into the room, away from the window wall (Fig. 1).

Figure 1: Section of daylight levels from spot measurement in architectural office.

In spot 10 (Fig. 1) in the afternoon the illuminance increases because the light is on above this specific point. The passive zone - the potential light penetration zone as referred above - was monitored to exceed not more than three meters in depth even if the windows are located high in window wall [3], which is the basic parameter for sufficient light penetration [4]. More specifically, the 300 lux required for office work is available only up to 2,9m (Fig. 2) from the windows instead of 6,8m as it was expected.

Figure 2: Floor plan with indicated passive zone (overcast sky). (Source: Choudhary, Limpou, Lytra, Sarkar, 2009)

Some questions, such as which is actually the potential passive zone in deep plan offices, which parameters and up to which extend they influence its depth, has raised from this observation and are going to be studied further. The method to investigate this hypothesis is to specify during step one these parameters and their role to building’s performance. In step two, a series of parametric simulations are developed to assess the most important factors – window size, external obstruction, and surfaces reflectance - assumed from the previous discussion. Therefore, a typical office environment is modelled and simulated in Ecotect

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(v5.6.2008) [5] and Radiance (2000) software [6] due to its accuracy in the prediction of daylighting respectively. The study concerns cloudy climates, so light availability which derives from diffuse sky illuminance is taken into account. Since CIE Overcast sky type is used, Daylight Factor is another critical point that is discussed and more specifically, the relation of average DF (a quantitative parameter) with light distribution, since not only light quantity but also quality, which the well distributed light gives, plays a significant role [4]. Accounting all observations and parametric studies mentioned, this paper comes up with the assumption that passive zone depth needs to be redefined in deep plan offices, since the optimum required 300lux reaches in depth approximately one time the room height and rarely two times the window head height.

affects directly also the no-sky line point in a room [8]. She also remarks that further from this point the room receives no direct skylight and remains gloomy. Figure 5 shows that in order sufficient amounts of skylight to penetrate a room up to a distance equal to twice the height of window upper edge, the angle of visible sky should be at least 60 degrees minus the window head obstruction. The angle of 60 degrees has nothing to do with the position of the sun, but arises from the available light in the sky. On the other side, minimizing the external obstacles means automatically that the surrounding area is not related to an urban environment.

2. LITERATURE REVIEW Generally, Baker and Steemers (2002) argue that the potential daylight penetration is determined by the geometry of the space, the configuration, position and size of the windows, the external skyline obstruction and the internal as well as external reflectance finishes [4]. The objective of this chapter is to analyse further and evaluate these criteria. 2.1. Skylight and external obstruction For cloudy climates as in the UK, it is considered that skylight is the main source of daylighting for buildings [4]. Therefore available visible sky, which is defined by external obstruction, o plays a significant role. A maximum 25 skyline obstruction angle above horizon from the centre of a window is proposed for daylight oriented buildings (Fig. 3) [7]. In case this angle is bigger, direct skylight penetration is decreasing while the external reflectance surface is increasing (Fig. 4).

Figure 5: Skylight penetration up to two times the window head height (Source: after CIBSE, 1999)

2.2. Window size and position Not only the surrounding built environment but also the apertures define the potential skylight availability in a space. In many studies, it is affirmed that except of window position on the wall, the window size is important for daylight oriented buildings. There are three rules of Thumb that are quoted in the literature for sizing window glazing – ratio window/wall area=35%, ratio window/floor area = 10% and ratio window/total room area = 4% [1], [7]. 2 In a typical example of a 60m rectangular room (6x10x3m), according to the first two equations the 2 window area is equal approximately to 6m whereas 2 according to the third equation is 8,6m - almost the half of the wall. For spaces with depth less than 8m a window to wall area ratio of 20% [1]. 2.3. Daylight factor

Figure 3: Shading by neighbouring buildings (Source: after CIBSE,1999).

Figure 4: Shading by high neighbouring buildings (Source: after CIBSE,1999).

As Dietrich (2006) points out, insomuch the light spreads linearly, shading from opposite buildings

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Another important criterion that is often applied in design is the daylight factor, i.e. the value that determines the quantity of daylight supply at a specific workplace [4]. Daylight factor describes the illuminance on an interior work plane in relation to the outdoor illuminance under an overcast sky [7]. Another assessment criterion for skylight is the average daylight factor (Dav), which is estimated 2 according to the formula Dav=AgxθxT/A(1-R ), where A is total internal surfaces area, Ag – glazing area, θ – angle of visible sky, T - glazing transmittance properties and R - interior surface reflectances) [1]. Dietrich (2006) contends that this equation shows that amount of interior daylight is determined solely by space’s geometry but not by exterior illuminance and external reflectances [8]. As far as the last is concerned, Bell and Burt (1995) note that when external obstacles obscure the view, reflected light goes further from the no-sky line point, i.e. the point in the room that direct skylight cannot reach [9]. Taking into account the above proposed premises, i.e. Ag/A = 1/25 (window/total room area

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

ratio), θ=60, T=0,8 (single-glazing transmittance) and R=0,7 (high reflectance value for offices), a room with an average DF=3,7% is calculated. Hence, room with an average DF=5% given, would be regarded as brightly daylit [2].

3. EXPERIMENTAL ANALYSIS

The second series of daylight simulations consist of varying the external obstruction. Except of the free-standing condition, one case with a sky o obstruction angle of 25 (as proposed in literature) o and one of 50 (heavy obstruction) are tested. In the first run, the window to wall area ratio is 35% (Fig. 8) while in the second is 50% (Fig.9).

3.1. Design example: Office space 2

The model of a 60m deep plan office (6x10x3m) in London is employed to assess the impact of the most important aspects such as window size, external obstruction and reflectance finishes on the depth of passive zone. This design example is modelled in Ecotect (v5.6.2008) and simulated in Radiance (2000), taking into account the previous assumptions as well as given benchmarks. The office is single lit from the south side and the window head height (Hw) is 2,7m. The aperture was highly placed on the wall, so that better light distribution is achieved. In addition, by this way, sky obstruction angle is measured from the point of 2m above ground [7]. The mean reflectance of enclosing room surfaces is 0,7. Sky condition was defined as overcast, with a reference of 8500lux. Under these sky conditions, a minimum DF=3,5% is required, so that the optimum 300lux for office work to be achieved.

Figure 8: Parametric studies – obstructions (a. freestanding building, b. obstruction angle of 25 degrees, c. obstruction angle of 50 degrees)

3.2. Parametric studies The first series of daylight simulations consist of varying the window size. Three cases are chosen regarding the window to wall area ratio. The first case was the proposed from literature window to wall area ratio equal to 35%, while a fluctuation of 15% defined the two other two cases (Fig.6). Namely, in case2 the window to wall area ratio is 50% (equal approximately to the ratio window/total room area = 4%) and in case3 the ratio is 20%.

Figure 6: Parametric studies – window area / wall area (a. w/w = 35%, b. w/w=50%, c. w/w=20%)

In literature, it is mentioned that a window to wall area ratio of 20% is appropriate for room depth less 2 than 8m [1], another 24m office area (4x6x3m) with the same characteristics is also studied under the same conditions (Fig.7). In all cases, the building is free standing so that only windows attribute to be testified. The window head height was constant at Hw=2,7m so as a thorough comparison for the depth of passive zone can be conducted.

Figure 7: Parametric studies – window area / wall area (a. w/w = 35%, b. w/w=50%, c. w/w=20%)

Figure 9: Parametric studies – obstructions (a. freestanding building, b. obstruction angle of 25 degrees, c. obstruction angle of 50 degrees)

The third series of daylight simulations consist of varying reflectance values. Mean internal (in enclosed room surfaces) reflectance values of 0,5, 0,7 and 0,9 (almost unrealistically high) are used in order to specify the impact of internal reflectance attributes (or internally reflected light component). Keeping constant the mean internal reflectance to R=0,7, different external reflectance values of 0,5, 0,7 and 0,9 are tested to verify the influence of the externally reflected light component. Composing the two other cases in a third, where internal and external reflectance values change similarly, examines the contradiction between reflectance and obstruction attributes that influence daylight penetration, since daylight factor is the sum of skylight component, external reflected light component as well as the internal reflected light component [4]. 3.3. Results discussion The following sections (Fig. 10, 11) examine different ratio of window/wall area and their impact on average daylight factor as well as depth of passive zone. Although in the case of window to wall area ratio of 50% - i.e. the window area covers the 1/25 (4%) of the total room surface - an average DF of 5% is reached, the depth of passive zone does not exceed 4m. It is important to mention that fluctuations of the graph (Fig. 11) are not

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proportional since there is a remarkable increase of 20% in daylight penetration from 35% ratio to 50%. Whereas from 20% ratio to 35%, it increased by 12%. Cases of more than 50% window to wall area ratio were not taken, due possible overheat problems during summer period.

c.

Figure 12: Light simulation of an 60m2office - RAD Daylight Factors (sky illuminance=8500lux) - window/wall: a) 20%_ DFav=3,1%, b) 35%_DFav=3,7%, c) 50% _ DFav=5,0%

Figure 10: Plot of calculated average DF% against room window area for overcast sky condition (8500lux).

In order to testify the limit of 8m depth in case of window to wall area ratio of 20%, a smaller model of 2 a 24m deep plan office (4x6x3m) with the same characteristics as the previous one was simulated. Hence also in this case, ratio 20% has not given the respected results and indeed average DF and daylight penetration were even smaller (Fig. 13, 14). Although the quota difference of average DF for each ratio is higher, in no case the limit of 4m depth is exceeded. It is important to mention that in this case of room depth equal to 6m, average DF and light penetration depth are changing proportionally to window area size.

Figure 11: Plot of penetration depth against room window area for overcast sky condition (8500lux).

The window area seems to influence more the quantity of light levels in the room than daylight distribution. Although the average daylight factor values seem satisfying for all of three case - above 3% for offices - the back of the room is still gloomy, since almost the rear half of it gets no more than DF=1% (Fig. 12).

Figure 13: Plot of calculated average DF% against room window area for overcast sky condition (8500lux).

a.

Figure 14: Plot of penetration depth against room window area for overcast sky condition (8500lux).

With a fixed ratio of window size (window / wall area=35%), light distribution in the room varies according to the sky obstruction angle. For an o increase of 25 to the obstruction angle, the depth of passive zone as well as the average DF decreases by 10% (Fig. 15, 16). Hence, from figure 15 the average DF seems satisfying (more than 3% required for offices) even if there is high obstruction level. Generally, although when increasing skyline obstruction, the external reflectance surface is

b.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

increased, the light levels are decreased. From the above one could conclude that obstruction influence overcomes reflection contribution.

Figure 15: Plot of calculated average DF% against room window area for overcast sky condition (8500lux).

Figure 16: Plot of penetration depth against room window area for overcast sky condition (8500lux).

Important observation from this graph is that even if in the free-standing building with an average window area ratio, the depth of passive zone reaches 3,30m instead of 5,4m, which was respected according to the existing rule of Thumb – i.e. approximately 1,2 times the window head height, as far as standard light levels required for office work (Fig. 17).

offices, since they define the potential amount of light penetration into a room.

Figure 18: Plot of calculated average DF% against room window area for overcast sky condition (8500lux).

Figure 19: Plot of penetration depth against room window area for overcast sky condition (8500lux).

Surface reflection seems to contribute almost the same to light levels and light delivery into the room. From figures 20 and 21 becomes apparent that an increased by 0,2 reflectance value contributes approximately 20% to light levels and light penetration as well.

Figure 20: Plot of penetration depth against room window area for overcast sky condition (8500lux). Figure 17: Light simulation of an 60m2office - RAD Daylight Factors (sky illuminance=8500lux) for free standing building - DFaverage =3,7%

According to previous observation, the case of window to wall area ratio of 50% comparing to the typical ratio of 35% not only performs better in light levels but also in light distribution. Therefore the case of w/w=50% was tested with external obstacles in order to examine which of the two factors influences more daylight availability in the room. Figures 18, 19 indicate that external obstacles decrease the average DF and the daylight penetration but in a lower quota (almost the half of 10%) than in the case of smaller windows. So it can be derived that windows size plays a primary role to daylit oriented

Figure 21: Plot of penetration depth against room window area for overcast sky condition (8500lux).

Situation becomes more complicated when reflection from surrounding surfaces occur. In this second case, the impact of different external reflectance values are tested, while the mean internal is kept

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constant at R=0,7. From the following graph (Fig. 22) it is obvious that higher external reflectance values are of limited results. When external reflectance surface is doubled, it contributes by 10% to light delivery deeper in the room. In case that external and internal reflectance values change similarly (Fig. 23), for a 0,2 reflectance value increase, a minimum increase of 25% in daylight penetration is observed. The peak in value 0,9 for the free-standing case indicates the higher impact of internal reflectance finishes on daylight penetration comparing to external.

Figure 22: Plot of penetration depth against room window area for overcast sky condition (8500lux).

As far as average daylight factor is concerned, in most cases it is over 3%. Hence, this fact does not confirm the daylight brightness of the space, since light distribution remains the main problem. The undertaken parametric studies also confirmed that window size has a greater impact on average DF than in penetration depth, since they are the primary factor determining the amount of light entering the space. External obstacles, for an increase of 25 degrees in sky obstruction angle, present a decrease of 10% in average DF as well as passive zone depth. From the above results one can conclude that the impact of sky obstruction overcomes slightly the impact of external reflectance premises in daylight penetration. This is also indicated from external reflectance test, which improved the situation but of limited results. In contrast, internal reflectance premises seem to have an impact of 20% on light penetration depth. Overall, deep plan space geometry, built density and available diffuse illuminance in cloudy climates as UK do not imply daylight autonomy for a big part of the year in office buildings.

5. ACKNOWLEDGEMENTS This paper is based on work undertaken for an MSc Research Paper in Sustainable Environmental Design at the Architectural Association School in London. I would like to thank my MSc course director Dr. Simos Yannas for his kind guidance on this project.

6. REFERENCES

Figure 23: Plot of penetration depth against room window area for overcast sky condition (8500lux).

4. CONCLUSIONS As stated in the introduction, passive zone in deep plan offices is observed not to follow the practical limit of two times the window head height. This research proves this assumption to be justified as far as daylight assess is concerned. The experimental analysis, which has been conducted under three main aspects: building obstructions, window size and reflectance finishes, seems to prove that small window area and external big obstruction could be the reasons for limited daylight penetration. In fact, the results indicate that daylight penetration in deep plan offices at most cases reaches in depth approximately the room height and rarely goes beyond one and a half time the window head height. Even if benchmarks or other values better than these are tested, the depth of passive zone is not improved more than 30%.

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[1] BRE (1998). GPG 245: Desktop guide to Daylighting. pp.5-9. Crown. [2] The society of light and lighting (2006). Lighting guide 7: Office lighting. pp. 15, 34-36. Chartered Institution of Building Services Engineers, London. [3] Choudhary, M. Limpou, K. Lytra,V. and A. Sarkar (2009). Architects Office, Covent Garden – Term 1 Project. MSc SED 2008-2009. Architectural Association, London. [4] Baker, N. and K. Steemers (2002). Daylight Design of Buildings. pp. 32-34, 43-46, 60-68, 222-224. James & James Science Publishers. [5] Ecotect (v. 5.6, 2008). Square One / Autodesk [6] Radiance (2000). Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory. [7] CIBSE (1999). LG10: Daylighting and window design. pp. 16-17, 20, 24, 27-28. Chartered Institution of Building Services Engineers, London. [8] Dietrich, U. (2006). Daylight Characteristics and Basic Design Principles, in: Lighting design: principles, implementation, case studies. pp.1923, Birkhauser. Edition Detail. [9] Bell,J. and Burt, W. (1995). Designing Buildings for Daylight. pp 28-31. BRE Publications.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Decision making in selecting the best matching hybrid lighting system Mohammed MAYHOUB1, David CARTER2 1

School of Architecture, University of Liverpool, Liverpool, UK - on leave from Al-Azhar University, Cairo, Egypt 2 School of Architecture, University of Liverpool, Liverpool, UK

ABSTRACT: Part of the lighting designer’s task is to decide whether daylight or electric light best meet user needs, architectural requirements and lighting guidelines. The desire to maximize the benefits of both daylight and electric systems has lead to the recent development of a number of hybrid lighting systems, each with different characteristics and performance. These systems offer many advantages, but because of their nature, they present very different decision making problems to designers than those of conventional lighting methods. A multi-criteria decision making approach is suggested to help this process, in which alternatives and criteria were defined and treated numerically to select the preferred choice. Sensitivity analysis has been carried out to examine the impact of modifying the importance of the criteria in the alternative selection. Results imply that the on-going criteria tend to influence alternatives ranking more than the one-off criteria. Keywords: Hybrid lighting systems, Decision making, Alternatives, Criteria, Sensitivity analysis

1. INTRODUCTION Daylight is the preferred source in buildings due to its beneficial effect on human well-being and performance. Its potential to conserve energy and hence protect the environment has stimulated interest as an electric lighting substitute. The recent development of ‘daylight guidance technology’ allows redirection of daylight into areas of buildings that cannot be lit using conventional glazing. The main guidance types are the commercially successful tubular daylight guidance systems, and the newer hybrid daylight/electric systems (HLS). The later has different approaches to combine both sources of light; which consequently led to a large diversity in terms of light collecting, guiding and distributing, in terms of costs and benefits, and in terms of performance and influences. Because of the variations in the HLS, the decision maker(s) need to know which system best suits building needs and budget. This study investigates selecting alternative HLS and develops a decision making procedure which can be applied to real cases.

2. HYBRID LIGHTING SYSTEMS Throughout the last decade many HLS have been developed in which daylight is captured and combined with electric light prior to delivery within a building via an output device similar to a luminaire. HLS consist of three parts. The external part, mostly called collector, collects and concentrates sunlight. The internal part, mostly called diffuser, spreads transported daylight in the required space. Guidance system; which delivers collected sunlight to the diffuser. A variety of methods are used to collect sunlight, deliver it into remote spaces, and distribute it over

required area. Control systems regulate the electric flux output to top up deficiency of natural light supply. The current study will investigate only the three HLS considered have high potential to penetrate the market. These are; hybrid solar lighting (HSL) and solar canopy illuminance system (SCIS) which have been installed for real demonstration, and Parans system which is commercially available. 2.1. Hybrid Solar Lighting The Hybrid Solar Lighting (HSL) collector is a 1.22m-diameter parabolic sun-tracking mirror with an elliptical secondary mirror (Fig. 1-A). The latter separates the visible and infrared portions of sunlight and focuses the visible sunlight into a bundle of optical fibres; which delivers the sunlight to the end of a side emitting acrylic rod located inside a conventional electric luminaire also equipped with dimmable fluorescent lamps. A control system tracks the sun; light sensors monitor daylight levels; and electronic dimming ballasts regulate the electric light output to a pre-determined level [1]. A second type of luminaire uses end emission from the fibres and has a light distribution similar to a parabolic reflector lamp. 2.2. Parans System The Parans sunlight collector is a roof or façade 2 mounted 1m modular solar panels containing 64No Fresnel lenses (Fig. 1-B). Each lens is able to track and concentrate sunlight into optical fibre. Sixteen fibres are combined into a cable each of maximum length 20m. The tracking is controlled by a microprocessor which is continually fed information from a photo-sensor which scans the sky to detect sun path. The system has five luminaire types, three of which are hybrid luminaires equipped with fluorescent or CF lamps which dim automatically depending on sunlight conditions [2].

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Figure 1: A: HSL collector, B: Parans collector, C: SCIS collector

2.3. Solar Canopy Illumination System Solar Canopy illuminance System (SCIS) is a facade mounted system collects sunlight using a grid of mirrors located inside an enclosure. On the façade each unit is approximately 3m wide x 1.2m high (Fig. 1-C). This is connected to a 0.25m high duct which extends some 10m into a building. The orientation of the mirrors changes with sun position. By a series of lenses and mirrors the light is concentrated and redirected into a rectangular cross section guide lined with multilayer optical film (MOF) which has high reflectance at all angles, and optical lighting film (OLF) which reflects light preferentially. Fluorescent lamps located inside the guide. Sunlight travels along the guide using total internal reflection within the MOF until hits an extractor material made of OLF. This diffusely reflects the light and the portion that no longer meets the angular conditions for total internal reflection exits the guide via the bottom surface. A control system maintains the desired interior illumination level [3].

3. NEED FOR DECISION MAKING Broad variation in HLS characteristics means decision must be made based on system performance, economics, relationship with the host building and nature of HLS components. Each of collector, guidance and diffuser may vary in size, mounting method, flexibility and technology; hence vary in performance, economics, compatibility and suitability. Selecting a HLS for purpose and budget has to take in consideration these variables. 3.1. Systems components and technologies - Collector: in HSL is a roof mounted mirror, while in Parans it is a roof or façade mounted solar panels, though it is a facade attached canopy in SCIS. All collecting devices are strongly recommended to be south oriented. - Guidance: both HSL and Parans guide sunlight via flexible fibre optic cables of few centimetres diameter, whilst SCIS uses a 60cm-wide x 25cm-high rigid ducts. Fibre optics lengths are as long as 20m, meanwhile illuminance ducts are of about 12m. - Diffuser: HSL outputs are either a side emitting acrylic rod located inside a conventional 1.2m x 0.6m electric luminaire, or end emission fibres have a light

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distribution similar to a parabolic reflector lamp. Parans custom designed luminaires are PMMA diffusing sheets with sizes from 45 x 45 cm to 90 x 90 cm, or spotlight luminaire. SCIS employs the traditional 60cm-wide linear ceiling luminaire. - Technology: both HSL and Parans system use high-tech to collect sunlight, which track sun path and highly concentrate its ray (up to 1000 times) to be transferable via small sections of fibre optics. SCIS tracks and concentrates sunlight some ten times and deliver it via relatively big ducts. 3.2. Systems influences The variations described above, in components and technologies, lead to differences in performance, economics, compatibility and suitability. 3.2.1. Lighting performance Lighting performance can be determined by the amount of delivered sunlight, overall efficiency and lighting quality. High concentration of sunlight makes system work efficiently only under clear sky condition, whilst a low concentration level allows a portion of skylight to be delivered. Overall efficiency depends on optical characteristics of every component and number of optical processes, where light loss occurs with every process. Uniform distribution and consistency level enhance lighting quality. Efficient diffusers allow light to be evenly distributed and avoids lighting problems. Sunlight concentration affects lighting consistency; the more concentration, the less consistency is obtained. 3.2.2. Economic performance Economical performance is vital for HLS to be a convincing alternative to electric lighting systems. Lifetime costs and benefits determine whether it can replace conventional electric system or not. Costs include initial and running costs. Both costs and benefits include tangible and intangible aspects. Initial capital cost depends on manufacturing complexity and production volume. Installation cost depends on system size, weight, mountain location, building modification necessity, and labour skills required. Intangible cost may occur in loosing rental area for ducts routes or so. Benefits may include for example, besides saving energy, improving building occupant’s well-being due to the beneficial effects of enhanced daylight, thus raising users’ productivity.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

3.2.3. System-building relationship (compatibility) System-building relationship can be determined by system’s ability to adapt to new and existing buildings. Structural supports may be required to hold collectors weight and resist the wind force. Facade attached collectors influence its appearance. Interior design may be affected by system guidance and outputs. Wall and ceiling holes are required to accommodate the guidance, which additionally needs to meet fire protection compartment requirements. Big-section guidance may need special arrangements. Horizontal routes need to be coordinated with other building networks. Vertical routs may disturb space function or interior design. 3.2.4. Possibility of use (suitability) Diversity in HLS features enables them to fit into different building forms and types. Facade mounted systems suit multi-storey buildings regardless number of stories; however they are strongly recommended to be south oriented. Sunlight can be delivered up to 20m into the building. Roof mounted systems are more suitable for deep-plan buildings with an average of three stories. High attention has to be paid in low rising buildings to avoid sunlight obstructs. Guidance ducts with side emitting provide linear luminaires that are more likely to be used in open plans. End emitting guidance provide variety of spot luminaire and conventional like luminaires which can be used for a wide range of purposes.

4. DECISION MAKING METHODOLOGY The objective of the decision maker(s) is to rank alternatives in terms of their ability to meet building (or space) needs and budget, and come up with a choice of one of them. To make a perfect decision some criteria have to be defined and the performance of each alternative has to be measured in terms of these criteria. Because of the variety of alternatives and the decision criteria, the Multi-criteria decision making (MCDM) approach appears to be a reasonable way to make these decisions. In this paper, three HLS assumed alternatives for a general case and decision has to be made to decide the best selection. A set of criteria was defined, depending on HLS analysis, to measure alternative performance. The decision criteria have been assigned importance weights. A widely used MCDM method is utilized to rank the alternatives; after applying three-step process in which weighting (of criteria), rating (of performance) and evaluating (of alternatives) have been carried out. Impact of changes in the evaluation process inputs on the decision making output has been discussed. An online survey was conducted, targeted at decision makers in the fields of building design and operating. This was designed to measure to what extend each HLS component or requirement was been preferred. The decision criteria relative importance weights were derived from recipients responses. Forty-eight responses were received from twelve countries spread in five continents. The values obtained were used to examine the MCDM method and the impacts of changes in importance weights and performance measures.

5. MULTI-CRITERIA DECISION MAKING The MCDM is one of the most well known branches of decision making. It uses numeric techniques to help decision maker(s) choose among a discrete set of alternative decisions. This is achieved on the basis of the impact of the alternatives on certain criteria thereby on the overall utility of the decision maker. 5.1. The MCDM problem Although MCDM methods may be widely diverse, many of them have certain aspects in common. These are the notions of alternatives and criteria. Alternatives usually represent the different choices of action available to the decision maker(s). Decision criteria represent the different dimensions from which the alternative can be viewed. Each criterion needs to be assigned relative weight of importance [4]. An MCDM problem, with m alternatives and n criteria, can be easily expressed in a matrix format. A decision matrix A is an (m x n) matrix; in which decision maker(s) has to determine aij measures the performance of alternative Ai when it is evaluated on terms of decision criterion Cj (for i = 1, 2, 3, ..., m, and j = 1, 2, 3, ..., n). For each criterion the decision maker(s) has to determine its importance, or weight wj. Figure 2 represents the typical MCDM problem examined in this paper. Criteria ... C2 C3 Cn C1 Alts (w1 w2 w3 wn) ...

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Figure 2: A typical decision matrix

Three steps have to be followed, as presented in sections 6.1 – 6.3 respectively, to utilize MCDM: A. Define the set of alternative and the set of decision criteria. B. Attach numerical measures to the relative importance of the criteria and to the impacts of the alternatives on these criteria. C. Process the numerical values to determine a ranking of each alternative. 5.2. The weighted product model The weighted product model (WPM) can be considered a modification of the weighted sum model (WSM); the earliest and probably the most widely used method [5]. Whilst the WSM should be used only when the decision criteria can be expressed in identical units of measure, the WPM eliminate any units of measures which makes it suitable for the current application. In the WPM each alternative is compared with the others by multiplying a number of ratios, one for each criterion. Each ratio is raised to the power equivalent to the relative weight of the corresponding criterion.

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In order to compare two alternatives AK and AL the following product [6] has to be calculated: R(AK/AL) =    

(1)

Where n is the number of criteria, aij is the th performance measure of the i alternative in terms of th the j criterion, and wj is the weight of importance of th the j criterion. If the term R(AK/AL) is greater than one, then it indicates that alternative AK is more desirable than alternative AL. The best alternative is the one that better than or at least equal to all the others.

6. DECISION MAKING PROCESS In order to apply the WPM method, four inputs have to be determined. These are the alternatives, the criteria, relative importance weights of the criteria and performance measures of the alternatives. Then pair-wise comparison will be made to rank the alternatives and determine the preferred choice. 6.1. Defining the alternative and criteria Suppose decision maker(s) is planning to install HLS, review of HLS [7] shows that HSL, Parans and SCIS systems are intending to be the most promising HLS. Therefore, they are defined as the most suitably available alternatives. Defining appropriate criteria able to measure different aspects of the alternatives are more complicated. The defined criteria should be systemic, reliable, measurable and comparable [8]. Defining criteria in this study based on the authors knowledge and analysis of hybrid systems’ components and performance; previously discussed in Sec. 3. Criteria defined to cover architectural, technical, economical and operational aspects (see list of the criteria in table 1). Social criteria, such as users’ productivity improvement or building prestige enhancement due to use of natural light, may be considerable if electric lighting system is considered one of the alternatives. Table 1: Decision criteria relative importance weight

Decision Criteria Lighting Quality & Quantity Ease of Maintenance Cost Fire hazard Luminaire Flexibility Light Guidance Size Possibilities of use Light Collector Location Ease of Installation

Relative Weight 13.1 % 12.1 % 12.1 % 11.9 % 10.8 % 10.3 % 10.2 % 9.9 % 9.5 %

6.2. Numerical measures Importance weights and performance measures are unavailable data and have to be determined by decision maker(s). Numerical values of the weights or the performance can be determined by subjective, objective, or combined methods. The subjective methods depend only on the preference of decision maker(s). Contrarily the objective values are

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obtained by mathematical methods based on the analysis of initial data. It can said that none of them is perfect, so combined methods are suggested [8]. In this paper, combined method was used. Values obtained from the survey are the recipients’ subjective evaluation. These values numerically treated to obtain the importance weights and performance measures. Practically, decision maker(s) in each case has to determine the more likely related values for their situation; taking into account building use type and times, building form and orientation, location and budget. 6.2.1. Weighting Recipients have weighted the criteria and the importance weights averages have been calculated. Then normalized to add up to one and ranked as listed in table 1. In reality, change of priorities responses to decision maker(s) appraisal of the real situation, which is possibly depends on client’s needs, customers’ complains or even feed backs. Reprioritization leads to changes in the criteria importance weights, and as a result changes in the alternatives preferences. For instance, an existing building with low clear height; light guidance size will be of greater importance than new building or high clear height building. ‘Light collector location’ criterion, in another example, may be of high priority in a building with a sensitive iconic form. 6.2.2. Rating Performances of alternatives corresponding to each criterion have been derived from recipients’ preferences. For example, regarding ‘light collector location’ preferences; valid responses percentages were as follows: 65.6% prefers roof mounting, 9.4% facade attached, 6.3% facade concealed, and 18.8% any method. HSL, as a roof mounted system, obtained performance measure of 84.4% (65.6% + 18.8%). Since Parans is a roof mounted or facade attached system, it obtained 93.8%. SICS, a facade attached or concealed system, obtained 34.5%. Since performance measure corresponds to decision criteria, corresponding to ‘light collector location’ criterion in iconic building will widely vary. Roof mounted method may obtain in this case 100% preference rather than 65.6% to avoid influencing elevations appearance, or obtain 0% if it is a doom roofed building and roof mounting is conceptually unacceptable. In order that, as said in the weighting, in reality change of rating could happen in response to specific situations. 6.3. Determining alternatives ranking Decision matrix includes all alternatives and decision criteria was set in as illustrated in table 2. Obtained relative weight of importance of decision criteria and performance measures of alternatives were filled in the matrix. Considering presented values in table 2, equation 1 was used to compare each two alternatives together. The following relations are produced: 0.121 0.095 = (0.30/0.18) x (0.57/0.54) x R(HSL/Parans) 0.102 ... x (0.17/1.00) = 1.03 > 1 Similarly, we also get: R(HSL/SCIS) = 1.15 > 1 , R(Parans/SCIS) = 1.12 > 1

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Cost

Ease of installation

Ease of maintenance

Collector location

Guidance size

Luminaire flexibility

Light quality & Quantity

Fire hazard

Possibilities of use

Table 2: Decision making matrix

0.121 0.30 0.18 0.91

0.095 0.57 0.54 0.17

0.121 0.72 0.53 0.38

0.099 0.84 0.94 0.34

0.103 0.87 0.90 0.30

0.108 0.93 0.93 0.50

0.131 0.42 0.09 1.00

0.119 0.50 1.00 0.50

0.102 0.17 1.00 0.33

Decision Criteria Alts HSL Parans SCIS

Weight Rating Rating Rating

(0) rate means no fit at all, (1) rate means excellent fit. Therefore, the best alternative in this case is HSL system, since it superior to all other alternatives, then Parans, and finally SCIS.

’ k,i,j  100

(4)

In order to determine the most critical criterion a total of n x m (m – 1) values need to be calculated. For example, the minimum quantity (expressed as %) needed to change the current weight of ‘light quality’, so consequently the current ranking of HSL and Parans systems will be reversed; can be calculated using relation (3) as follows:

7. SENSITIVE ANALYSIS 7.1. Background and definition In the WPM method weights assigned to the decision criteria attempt to represent the genuine importance of the criteria. In the above case, ‘light quality ‘criterion obtained the best weight, therefore it intuitively attempts to be believed the most important criterion. Since the defined criteria in the current case have different units of measure, and cannot be all expressed in quantitative terms, then it is difficult to represent accurately the importance of these criteria. In a situation like this, the decision making process can be improved considerably by identifying the critical criteria. Sensitivity analysis is the approach by which the critical criteria can be identified to determine what is the smallest change in the current weights of the criteria, which can alter the existing ranking of the alternatives? The most critical criterion can be determined to see whether it will alter the rank of any two alternatives or just change the rank of the best alternative.

Z(HSL/Parans)

=

    



x

= 12.83



The quantity 12.83 satisfies (4) as it is less than 100. Therefore the value of ’ k,i,j have to be bigger than 12.83. Thus the modified weight w* of the ‘light quality’ criterion has to be reduced 12.83% at least. It can be calculated as follows (before normalization): = wk – (wk x ’ k,i,j ) w*K = 0.131 – (0.131 x 12.83%) = 0.114 The use of the modified weights values (after normalization) makes the relation R(HSL/Parans) equal to one. Any further reduction in the modified weight of ‘light quality’ criterion makes R(HSL/Parans) less than one, which accordingly reverses the rank and makes Parans alternative superior to HSL. Working as above for all possible pairs of alternatives, all possible Z values can be determined as depicted in table 3. Note that n/f stands for nonfeasible value, which is value that cannot satisfy the constraint given as (4). That means it is impossible to reverse the existing ranking of pair of alternatives by making changes on the current weight of the corresponding criterion. It can be observed that the criterion with the highest weight is the critical criterion in two cases only.

7.2. Determining the most critical criterion Let ’ k,i,j (1  i  j  m and 1  k  n) denote the minimum percent of change in the current weight wk of criterion Ck so that the ranking of alternatives Ai and Aj will be reversed. When the WPM method is used, the quantity ’ k,i,j is given as follows [5]: ’ k,i,j > Z if, 0  Z  100 ’ k,i,j < Z if, Z < 0 Where Z is defined as: Z=[(log(   ))x100 ]/[(log(aik/ajk))xwk] (3) Also, the following constraint has to be satisfied: Table 3: All possible Z values

Luminaire flexibility

Light quality & Quantity

70.89 282.87 182.02

-249.07 115.01 157.73

-934.81 100.41 126.33

172.38 211.58

12.83 -36.25 -124.4

-31.39 138.01

Possibilities of use

Guidance size

524.24 105.30 123.60

Fire hazard

Collector location

42.12 -58.78 -105.70

Ease of maintenance

HSL/Parans Parans/SCIS HSL/SCIS

Ease of installation

Pairs of Alternatives

Cost

Decision Criteria

-14.14 101.40 -197.26

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

7.3. Degree of criticality Importance ranking of the criteria may change after determining the critical criteria. The criticality degree, D’k, of criterion Ck is the smallest percent amount by which the current value of wk must change, so that the existing ranking of the alternatives will change [5]. That is, the following relation is true: = min 1  i < j  m {   } , for all n  k  1 D’k Therefore, from table 3, the criticality degrees are as depicted in table 4. Table 4: The criticality degree of the criteria

Decision Criteria Lighting Quality & Quantity Possibilities of use Fire hazard Cost Ease of Maintenance Light Guidance Size Ease of Installation Light Collector Location Luminaire Flexibility

D’ 12.83 14.14 31.39 42.12 70.89 100.41 105.30 115.01 172.38

8. DISCUSSION Although HLS have a common concept they vary in features. That what makes a rational choice is a very difficult decision. Thus, this work aims to practice a method by which a particular HLS can be identified ideal for a particular application. The MCDM offers numerical methods to help decision maker(s). The WPM method, a dimensionless MCDM method, was utilized to make a decision in a general case, in which a HLS is desired to be selected. In order to apply the WPM method, a set of three HLS was nominated as alternatives. A set of nine decision criteria were defined based on alternatives’ components and performance analysis. The relative importance weights of the criteria and the alternatives performance were derived from decision makers’ responses to an online survey. Changes in these values are more likely to happen with every new situation to reflect the new circumstances. ‘Light quality’ and ‘ease of maintenance’ criteria, as whole life aspects, were selected by the surveyed decision makers as the most important criteria, in addition to the ‘cost’ criterion. Contrarily, ‘ease of installation’ criterion, as one-off aspects, emerged as the least important criterion. The criterion elected by decision maker(s) as the most important one is not necessarily to be the most influential or critical one; especially in cases where different units of measurement were used. Therefore, the criticality degree can be measured by the criterions ability to change the alternative ranking. The smaller change in the criterion weight required to alter the ranking, the more critical the criterion is. Thus, criterion that cannot alter alternatives ranking whatever change to its weight can be eliminated. A sensitivity analysis was carried out to determine critical degrees of the criteria. ‘Light

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quality’, the most important criterion was the most critical one as well. Only 12.83% reduction in its relative weight is enough to nominate Parans system the best alternative instead of HSL. In order to bring SCIS to the top, the ‘cost’ criterion is the critical one and its relative weight has to be increased 105.7% at least. Meanwhile, only 58.78% raise is enough to reverse SCIS rank with Parans system. Alternatives performance show close similarity on some criteria and wide variation on others. For example, HSL and Parans obtained 0.57 and 0.54 values respectively in terms of ‘ease of installation’, whilst SCIS obtained only 0.17, as SCIS collector and guidance are much bigger in size and weight, thus more supports and building modification are needed. In terms of ‘cost’ a big variation exists which reveals the decision makers acceptance of the systems’ payback periods. The difference between 0.91 obtained by SCIS and 0.18 obtained by Parans reflects the big difference between the costs of both of them. Similarly, Parans obtained 0.90 in terms of ‘guidance size’, whilst SICS obtained only 0.30 which demonstrate the difference between the smalldiameter fibre optic cables and the big-section illuminance ducts. Sensitivity analysis can be carried out to determine the critical changes in performance measures to change alternatives ranking. For example, to know the minimum change in Parans measure in terms of the cost to be ranked the best alternative. Performance measures sensitivity analysis is a subject for future research.

9. REFERENCES [1] LAPSA M., MAXEY L., EARL D., BESHEARS D., WARD C. & PARKS J. (2007) Hybrid Solar Lighting Provides Energy Savings and Reduces Waste Heat. Energy Engineering, 104 (4), 7-20. [2] Parans Solar Lighting. Available at: http://www.parans.com/Products/tabid/892/langu age/en-US/Default.aspx [Accessed 10/2010]. [3] ROSEMANN A., COX G., FRIEDEL P., MOSSMAN M. & WHITEHEAD L. (2008) Costeffective controlled illumination using daylighting and electric lighting in a dual-function prism light guide. Lighting Res. Technol. 40, 77-88. [4] TRIANTAPHYLLOU E. (2000) Multi-criteria decision methods : A comparative study. Dordrecht : Kluwer academic publishers. [5] TRIANTAPHYLLOU E. (1997) A sensitivity analysis approach for some deterministic multicriteria decision making methods. Decision Sciences, 28 (1), 151-194. [6] MILLER W. & STARR M. (1969) Executive decisions and operations research, Englewood Cliffs, NJ: Prentice-Hall Inc. [7] MAYHOUB M. & CARTER D. (2010) Towards hybrid lighting systems: A review. Lighting Res. Technol. 42, 51-71. [8] WANG J., JING Y., ZHANG C. & ZHAO J. (2009) Review on multi-criteria decision analysis aid in sustainable energy decision making. Renewable and sustainable energy reviews, 13, 2263-2278.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBN th xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Comparative Analysis of Admitted Luminous Flux and Daylight Spatial Distribution in Openings with Solar Control Devices Amilcar J. BOGO1, FERNANDO O. R. PEREIRA2, ANDERSON CLARO2 1

2

FURB, Regional University of Blumenau, Blumenau, Brazil UFSC, Federal University of Santa Catarina, Florianópolis, Brazil

ABSTRACT: The evaluation of daylight admittance through openings of solar control devices – SCD – is not a simple task, for the addition of obstacles near the opening modifies the quantity of daylight transmitted, as well as its trajectory to the interior. This paper shows the results of the comparative analysis of the luminous performance of openings with complex SCD geometry compared with others of differentiated geometry but with the same solar protection angle. A method analogous to a goniophotometer used in photometric studies in the laboratory was developed for this analysis, using computational simulation from a spatial representation virtual model of the inner environment. The method was implemented with the use of the APOLUX 1.0 daylight computational simulation program (validated), identifying admitted luminous flux and daylight spatial distribution under the interference of the SCD. Regarding the admitted luminous flux, for example, for a solar control device of 10 horizontal slats compared to one with 1 horizontal slat, there was a 3 to 6 times increase. The method developed permits the evaluation of daylight admission through openings with SCD, showing advantages in relation to the laboratory experimental methods, such as lower analysis time, lower cost and easy access to researchers interested in such methods. Keywords: luminous flux, solar control, openings, daylight

1. INTRODUCTION The amount of daylight transmitted through windows varies according to its optical properties: transmittance, reflectance and absorptance, which influence the transmitted fragments, reflected and absorted in the glass adopted in the openings, which in turn influence the quantity of thermal and luminous energy transmitted to the interior of buildings. According to [7], the transmittance, reflectance and absorptance properties are influenced by the direction of incidence on the material and by each radiation wavelength, with some materials being selective, that is to say, their optical properties vary according to the radiation incidence and wavelength. For simple openings with no obstacles or control devices, it is easy to calculate the estimated transmitted daylight, which depends mainly on glass transmittance and the light incidence angle. The addition of obstacles such as solar control devices close to the opening modifies both the trajectory and the quantity of daylight transmitted, affecting natural illumination in the interior of buildings. This influence occurs due to a partial obstruction / filtration of daylight incident on the opening, and due to a variation of the light direction for the internal environment because of multiple reflexion processes among the solar control devices. According to [8] and [5], for the characterization of the luminous behaviour of openings with protective obstacles (such as solar control devices SCD type which influence the admission of daylight to the interior environment), two optical properties must be

known: hemispheric directional transmittance (Tdh) and hemispheric bidirectional transmittance (Tbh). On the luminous characterization of openings, [5] presents characteristic luminous measurements of several materials for natural illumination, such as directional and bidirectional light transmittance measurements, prismatic film for glass, sunlight directing glass (lumitop) and plexiglas. [4] and [1] also present results for four types of glazed materials and / or solar control devices: diffuser (acrylic glass), light redirecting glass, light directing blinds, prism, laser cut panel, blinds and gratings. This work presents the hemispheric directional transmittance (the ratio between the admitted luminous flux - transmitted – and the incident one) for different types of windows with solar control devices, which characterizes the admitted luminous flux to the interior, according to what was presented in [6]. This study presents an alternative way to generate input data for more precise characterization of the luminous behaviour through the openings, assisting in the processof computer simulation of this phenomenon.

2. METHOD The method used was the computational simulation of daylight passing through an opening in a hollow hemisphere with a vertical base, which was the daylight resource (window), analogous to a goniophotometer used in photometric studies in the laboratory, [2]. This simulation of a virtual environment is identified in literature as the ideal study model for the luminous characterization of

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

openings for admitted light and its interior spatial distribution [1], as illustrated in Figure 1 below.

Figure 2: 1 HS (sectional view), 1 horizontal slat, with depth 3,466 m.

Figure 1 – Ideal set-up model configuration: hemispherical absorbing detector and virtual sun.

In the study, different solar control systems were comparatively evaluated for the quantity of daylight admission (luminous flux), and daylight spatial distribution. For the implementation of the method a special module of the APOLUX 1.0 daylight computational simulation software, [3], was used. This module identified the illuminance results in the outer glass plane that was adopted for the calculation of the admitted luminous flux under the interference of the solar control devices added to the window. The equivalent luminance of the window plane was identified for the spatial distribution of admitted light. This program was validated by [9], and is based on the Spherical Vector Model, which consists of a general globe reference by which all the relationships of visibility of this study’s object are defined. Different opening systems were evaluated in relation to the geometry (horizontal and vertical slats) and the reflectance of the solar control devices (75%; 20%), considering differentiated periods of solar incidence at 30 and 60 degree altitudes, and 0, 60 and -60 degree azimuths from the centre of the opening, depending on the situation. From the definition of CAD models in 3 D Face format, it is possible to simulate the luminous behaviour of different types of geometric configuration of solar control devices with the APOLUX program, which allows various parametric studies. Geometric configuration characteristics of the 2 solar control devices analyzed in the 4 m (2 x 2m) area, are presented below. Elements with horizontal slats on the opening: With a 30 degree frontal vertical obstruction angle: Type A: 1 HS, 1 horizontal slat, with depth 3.466 m:

Type B: 10 HS, 1 horizontal slat, with depth 0.346 m:

Figure 3: 10 HS (sectional view), 10 horizontal slats, equally distributed through the height of the window, with depth 0.346 m.

With a 60 degree obstruction frontal vertical angle: m:

Type C: 1 HS, 1 horizontal slat, with depth 1.154

Figure 4: 1 HS (sectional view), 1 horizontal slat, with depth 1.154 m.

Type D: 10 HS, 1 horizontal slat, with depth 0.115 m:

2

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 5: 1 HS (sectional view), 1 horizontal slat, with depth 0.115 m.

The depth dimensions of different slats were determined according to the two solar altitude angles of analysis (30 and 60 degrees) for the horizontal type solar control devices - SCD, aiming at shadowing the Sun’s rays in those solar height angles. Elements with vertical slats perpendicular to the opening: With a 45 degree lateral horizontal obstruction angle: Type E: 5 VS, 5 x 0,5m vertical slats, with 0,5m interval between them:

Figure 6: 5 VS (plan view), 5 x 0,5m vertical slats, with 0,5m interval between them.

Type F: 10 VS, 10 x 0,222 m vertical slats, with 0,222 m interval between them:

was determined considering a 45 degree lateral horizontal shadowing angle. The alteration in the dimensions refers to the definition of the different geometric configuration situations, one with five vertical slats and the other with 10. Calculating the Luminous Flux: Quantitative identification of daylight passing through the window in the hollow hemisphere model with an opening was obtained from a numerical report of luminance in the external plane of the glass, generated by the APOLUX Software. Because luminance (E) is equal to the luminous flux (Ф) divided by the area (A), the luminous flux (Ф) is calculated for each point of luminance measurement, where the values of luminance are identified in the window plane (in a set of “mapping” points of the whole window area) as being equal to the luminance (E) multiplied by the area:

Φ ≡ E× A

[01]

Thus, according to the contribution area of each point in the window (total area of the window divided by the number of “mapping” points = 121), the luminous flux of each parcel is identified as a point. The total luminous flux admitted through the window equals the total amount of partial luminous fluxes identified before. Calculating the Equivalent Luminance of the Window: The spatial distribution of admitted daylight is identified in concordance with the concept of equivalent luminance of the window. It depends on the luminance generated in the window, according to each point of luminance identified in the interior of the hemisphere, obtained from a numerical report generated by the APOLUX Software. Starting from the numerical data of luminance generated in the window (in the central opening point), dxf type images are created by the APOLUX Software Special Module, identifying the direction of different light vectors, from the center of the opening to the interior of the hemisphere, representing the spatial distribution of admitted daylight. The equivalent luminance of the window (L equiv) for each value of luminance (E) identified in the interior of the hemisphere according to the directions starting from the center of the opening was obtained from equation 2 below:

Lequiv ≡

E × r2 A × cos θ

[02]

Source: [08] Figure 7: 10 VS (plan view), 10 x 0,222 m vertical slats, with 0,222 m interval between them

For the SCD types with vertical slats perpendicular to the window, the depth of the slats

Where: A = window area; r = distance between the window’s central point and the luminance identification in the interior surface of the hemisphere. θ = angle formed between the direction normal to the opening and the internally reflected ray of light.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

3. RESULTS The results presented and analyzed herein refer to the admitted luminous flux and represent the quantity of light that passed through the window after undergoing the effect of solar control devices and passing through glass transmittance (85%), allowing the comparison of different types of elements according to the analyzed altitudes and azimuth angles, which represent the solar incidence in the opening. These results for the luminous flux (lm) are presented further on, in comparative tables for the types of solar control devices (SCD) analyzed according to their geometry and reflectance influence. 3.1 Daylight admission - Luminous Flux (lm): The values calculated for luminous flux were identified as specified below: Φ Ext (lm) Sun + Sky: luminous flux in the external vertical plane of the opening, situation without SCD due to the daylight resources Sun and sky; Φ Ext (lm) Only Sun: luminous flux in the external vertical plane of the opening, situation without SCD due to the daylight resource Sun; Φ Effect ECS (lm): luminous flux in the external glass only with the effect of SCD, due to the daylight sources Sun and sky; Φ Adm (lm): luminous flux admitted internally after passing through the glass, due to the daylight sources Sun and sky; directional transmittance Tdh: hemispheric according to the light incidence (altitude and azimuth): the quotient between the admitted luminous flux and the incident flux. The luminous flux results for comparative situations of solar control devices types (two by two), are presented below. These values are presented in tables, with the comparative results obtained for different conditions of daylight exposure and taking the solar control device types into consideration Table 1 – Comparative Daylight (Luminous Flux) admission for SCD types 1 HS and 10 HS

Sun Position – ALTITUDE 30° and AZIMUTH 0° Frontal daylighting Φ Φ Φ Ext (lm) SCD Tdh Effect Adm ECS Sun + Sky Types (%) lm lm 1 HS 6631 5637 1.72 326 818 10 HS 41347 35145 10.75 Analysis of the results: As observed in Table 1, there are variations in daylight admission for the same situation of shadowing opening through different types of SCD (1HS and 10 HS). For 10 HS compared to 1 HS, there was a 623.46% increase in the admitted flux (from 5637 lm

4

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to 35145 lm), due to an increase in daylight admitted by reflection in the 10 horizontal slats. Table 2 – Comparative Daylight (Luminous Flux) admission for SCD types 1 HS and 10 HS

Sun Position – ALTITUDE 30° and AZIMUTH 60° Side daylighting Φ Φ Φ Ext (lm) SCD Tdh Effect Adm Sun + Sky Types (%) ECS lm lm 111 693 1 HS 4967 4222 3.78 10 HS 18089 15375 13.76 Analysis of the results: As shown in Table 2, there are variations in daylight admission for the same situation of shadowing opening through different types of SCD (1HS and 10 HS), For 10 HS compared to 1 HS, there was a 364.25% increase in the admitted luminous flux (from 4221 lm to 15375 lm), due to an increase in daylight admitted by reflection in the 10 horizontal slats. Table 3 – Comparative Daylight (Luminous Flux) admission for SCD types 1 HS and 10 HS

Sun Position – ALTITUDE 30° and AZIMUTH 60° Side daylighting Φ Φ Φ Ext (lm) SCD Tdh Effect Adm ECS Sun + Sky Types (%) lm lm 106 378 1 HS 4946 4204 3.95 10 HS 18682 15880 14.92 Analysis of the results: The table 3 presented show that there are variations in daylight admission for the same situation of shadowing opening through different types of SCD (1HS and 10 HS). For 10 HS compared to 1 HS, there was a 377.73% increase in the admitted luminous flux (from 4204 lm to 15880 lm), due to an increase in daylight admitted by reflection in the 10 horizontal slats. Table 4 – Comparative Daylight (Luminous Flux) admission for SCD types 1 HS and 10 HS

Sun Position – ALTITUDE 30° and AZIMUTH 60° Side daylighting Φ Φ Φ Ext (lm) SCD Tdh Effect Adm ECS Sun + Sky Types (%) lm lm 127 805 1 HS 8977 7631 5.97 10 HS 54083 45971 35.96 Analysis of the results: As observed in Table 4, there are variations in daylight admission for the same situation of shadowing opening through different types of SCD (1HS and 10 HS). For 10 HS compared to 1 HS, there was a 602.42% increase in the admitted luminous flux (from 7631 lm to 45971 lm), due to an increase in daylight admitted by reflection in the 10 horizontal slats.

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Table 5 – Comparative Daylight (Luminous Flux) admission for SCD types 1 HS, 10 HS, 5 VS and 10 VS

Sun Position – ALTITUDE 30° and AZIMUTH 60° Side daylighting Φ Φ Φ Ext (lm) SCD Tdh Effect Adm ECS Sun + Sky Types (%) lm lm 1 HS 7669 6519 17.50 10 HS 26652 22654 60.81 37251 5 VS 17243 14656 39.35 10 VS 16776 14259 38.27 Analysis of the results: Table 5 shows there are variations in daylight admission for the same situation of opening shadowing through different types of SCD (1HS and 10 HS; 5 VS and 10 VS). For 10 HS compared to 1 HS, there was a 347.50% increase in the admitted luminous flux (from 6519 lm to 22654 lm), due to an increase in daylight admitted by reflection in the 10 horizontal slats. When comparing 10 VS to 5 HS, there was a reduction of 2.70% in the admitted luminous flux (from 14259 lm to 14656 lm), due to light loss in successive inter reflection processes between the 10 VS, where this process is more intense than with 5 VS.

A great variation in the luminous flux admission for situations of same solar protection angle and different physical configurations (1 HS e 10 HS) was identified and can be observed in this table. Table 8 – Comparative Daylight (Luminous Flux) admission for SCD types 5 PV and 10 PV with altitude and azimuth

Altitude 30° 5 PV 10 PV

Altitude 60° 5 PV 10 PV

Azimuth 14656 14259

Analysis of the results: As already identified, a small variation in the admitted luminous flux for the same solar protection angle situations and different physical configurations (5 VS and 10 VS) can be observed in this table. 3.2 Equivalent Luminance of the Window 2 (cd/m ): The calculated values of equivalent luminance of the window were identified to exemplify the four types of solar control devices (SCD) analyzed (spatial distribution of the admitted light in altitude and azimuth co-ordinates positioned in the window plane), as specified below: - Type A: 1 HS of 3.466m, 30° ALTITUDE, 0° AZIMUTH, (Sun + Sky) 80

2250

70

Table 6 – Comparative Daylight (Luminous Flux) admission for SCD types 1 HS and 10 HS

60

2000

50

1750

40 30

ALTITUDE

Sun Position – ALTITUDE 30° and AZIMUTH 60° Side daylighting Φ Φ Φ Ext (lm) SCD Tdh Effect Adm ECS Sun + Sky Types (%) lm lm 1 HS 7788 6619 15.37 43077 10 HS 27718 23560 54.69

Azimuth 27351 29275

1500

20 10

1250

0 -10

1000

-20 -30

750

-40

500

-50 -60

250

-70 -80

Analysis of the results: As observed in Table 6, there are variations in daylight admission for the same situation of shadowing opening through different types of SCD (1HS and 10 HS). When comparing 10 HS to 1 HS, there was a 355.94% increase in the admitted luminous flux (from 6619 lm to 23560 lm), due to the increase of daylight admitted through reflection in the 10 horizontal slats.

-80 -70 -60 -50 -40 -30 -20 -10

1 HS 10 HS Altitude 60° 1 HS 10 HS

0° 5637 35145 0° 7631 45971

Analysis of the results:

- 60° 4204 15880 - 60° 6619 23560

20

30

40

50

60

70

80

1 0

- Type B: 10 HS of 0.346m, 30° ALTITUDE, 0° AZIMUTH, (Sun + Sky) 80

8535

70 60

8000

50

7000

40 30

ALTITUDE

Altitude 30°

10

Figure 8: Spatial distribution of the admitted light in altitude and azimuth co-ordinates

Table 7 – Comparative Daylight (Luminous Flux) admission for SCD types 1 HS and 10 HS with height and azimuth variation, 75% reflectance, 0.15 m wall thickness

Azimuths 60° 4222 15375 Azimuths 60 6519 22654

0

AZIMUTH

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Figure 9: Spatial distribution of the admitted light in altitude and azimuth co-ordinates

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

- Type C: 1 HS of 1.155m, 60° ALTITUDE, 0° AZIMUTH, (Sun + Sky) 80

2500

70 60

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1750

ALTITUDE

30

1500

20 10

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750

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0

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1 0

Figure 8: Spatial distribution of the admitted light in altitude and azimuth co-ordinates

- Type D: 10 HS of 0.115m, 60° ALTITUDE, 0° AZIMUTH, (Sun + Sky) 80

21890

70 60

20000

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17500

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15000

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0

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30

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1 0

Figure 9: Spatial distribution of the admitted light in altitude and azimuth co-ordinates

4. CONCLUSIONS From the methods and proceedings identified in the revision of literature, and from the simulation task conducted, the conclusion was that one of the possible means to adequately characterize the luminous behaviour of openings with obstructions, like solar control devices, is the improvement of daylight simulation softwares through the use of algorithms, which could better represent the real physical situation. Both the APOLUX simulation software and other existent programs consider opaque surfaces as perfect diffusers. This diffuser opaque surface situation is found in some materials’ surfaces, as in the case of the solar control devices - wall or sill thickness - considered in the adopted simulation models. For the window glass representation, the program considers it to be a specular transmitting surface. There is also the need to define a generation of light performance computational simulation programs

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integrated to the CAD programs, allowing the architect to effectively simulate his ideas of the project as well as its realization. The results previously analyzed identified the expected variation (reduction and / or increase) of light admission and spatial distribution for the addition of different types of solar control devices (1 HS; 10 HS; 5 VS; 10 VS) in windows. The method presented helps in determining the variables of assessment of visual comfort (luminance of the source opening), contributing to the calculation of indices of visual comfort.

5. REFERENCES [1] ANDERSEN, Marilyne, DE BOER, Jan (2006) “Goniophotometry and assessment of bidirectional photometric properties of complex fenestration systems”. Energy and Buildings, Vol. 38, pp.836-848. [2] BOGO, Amilcar José (2007) “Método para Avaliação da luz Natural através de Aberturas com Elementos de Controle Solar”. Tese de Doutorado. Programa de Pós-Graduação em Engenharia Civil – PPGEC. Universidade Federal de Santa Catarina – UFSC, Florianópolis. [3] CLARO, A., PEREIRA, F. O. R., AGUIAR, G. P. (2003) “Desenvolvimento do Protótipo do Software LuzSolar para Análise e Projeto de Iluminação Natural em Arquitetura e o Fórum de Pesquisa & Urbanismo”. 1 Desenvolvimento da CELESC, Florianópolis/SC. [4] DE BOER, Jan (2006). “Modelling indoor illumination by complex fenestration systems based on bidirectional photometric data”. Energy and Buildings, Vol. 38, pp.849-868. [5] IEA. International Energy Agency (1999) “Measurement of luminous characteristics of daylighting materials”. A Report of IEA SHCP Task 21/ECBCS Annex29. [6] KESSEL, Jeffrey, SELKOWITZ, Steve (1984) “Integrating sphere measurements of directionalhemispherical transmittance of window systems. Journal of IES, October. [7] MCCLUNEY, R. (1987) “Determining solar radiant heat gain of fenestration systems”. Passive Solar Journal, Vol. 4, no. 4, pp 439-487. [8] PAPAMICHAEL, K., KLEMS, J., SELKOWITZ, S. (1988) “Determination and application of bidirectional solar-optical properties of th fenestration systems”. 13 National Passive Solar Conference. Massachusetts Institute of Technology. LBL-25124, March. [9] PEREIRA, Roberto Carlos (2009). “Metodologia Para Avaliação de Ferramentas de Simulação de Iluminação Natural Através de Mapeamento Digital de Luminâncias”. Tese de Doutorado. Programa de Pós-Graduação em Engenharia Civil – PPGEC. Universidade Federal de Santa Catarina – UFSC, Florianópolis.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The Light Comfort Zone of Micro-landscape Plant community– from the Viewpoint of Occupancy Environment CHUANG-HUNG LIN 1, CHIEN-YUAN HAN 2 , RUEY-LUNG HWANG 1 1

2

Department of Architecture, National United University, Taiwan Department of Electro-optical Engineering, National United University, Taiwan

ABSTRACT: Micro-landscape plant communities are quite common in building clusters, and with a typical example being the atrium. Situated in the sub-tropical regions, Taiwan (120.75 E, 24.54 N) is a place where the distribution of solar radiation is highly connected to people’s outdoor activities. Therefore, as the effects from sunlight and the coverage of a building structure may be accurately predicted, the conditions of human activity, as well as floral reproduction, can be settled in an accurate and comfortable manner. This research focuses on an atrium (44×52m) at National United University as an object of study. We investigated the disposition of the plantation and measured the Photosynthesis Active Radiation (PAR), compared and analyzed in terms of Relative Shine Hours (RSH) using computer simulations, thus producing distribution figures for the Daily Light Integral (DLI) inside the atrium. This method allows us to easily discuss the comfort range of growth conditions in the Micro-landscape plant communities and, at the same time, illustrate the important role that the climate scale plays in landscape design. Keywords: Photosynthetically Active Radiation, Daily light integral, Sunshine duration

1. INTRODUCTION Plant environmental stress constitutes a major limitation to crop production and plant growth, and these stresses to natural areas are closely related to such subjects as nutrition and water availability, in an investigated area. Meanwhile, the major contributing factor to plant growth and development within an occupancy area is the building pattern. Lighting, an influence issue to be discussed, has three principal characteristics that affect plant growth: quality, quantity, and duration. Quality refers to the spectrum of greatest effect on plant growth. It is common knowledge that photons with a wavelength between 400 and 700 nm (referred to as Photosynthetically Active Radiation or PAR) provide the energy required for photosynthesis. Quantity and duration refer to the intensity of and period of time exposed to the lighting, while the Daily Light Integral (DLI) is the amount of PAR received each day as a function of light intensity and duration. DLI is therefore an important variable in determining the influences of light on plant growth. Generally, formal garden projects of landscape architecture usually implement symmetrical shapes and placement within the garden space in order to create a clean and crisp look, rather than considering the daily light effect influenced by structures located near or adjacent to the garden. Thus, sun plants in the garden often fail to blossom and bear fruit as a result of a deficiency in the daily light integral. In contrast, prolonging daylight hours for shade plants usually causes their leaves to become pale or even to become sunburned, turn brown, and die. Therefore, small-scale and local levels of light are crucial factors to be considered in garden and landscape design.

If quantitative analysis of the local light environment can be performed in advance of plant cultivation and landscape design, the optimal light intensity of each locale or area can be determined in order to maximize photosynthesis and the growth of the plants. As the additional considerations of local light environments are involved in garden and landscape design, operating and maintaining the localized ecosystem in an efficient and economic manner will be consistent with the goal of sustainable development. In this paper, we propose a method by which to evaluate the local light environment in order to determine the suitable species of trees or seeds prior to afforesting a selected area. This study was begun by mapping daylight hours on the spring equinox, the summer solstice, the autumnal equinox, and the winter solstice of an atrium, whose daylight hours are influenced by adjacent or nearby structures. Afterwards, the PAR value of a reference spot in which the amount of daylight hours was not affected by structures was measured on the equinox. In consequence, the DLI value for each lot in the area can easily be predicted from the results obtained from mapping daylight hours and a reference PAR value. The DLI map, taking the localized daylight hours of an artificial afforestation area into consideration, could thus specify the species suitable for afforestation based on the scientific study.

2. SUNLIGHT CONDITIONS AND CHARACTERISTICS OF THE PLANTS When water and CO2 are not limiting factors, the rate of photosynthesis is proportional to the strength of sunlight. A single leaf normally has the highest rate of photosynthesis under a light strength of 13klux or 240 μmol/m2s, which is thus known as the

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

light saturation point (LSP). However, leaves produce shading effects on one another; thus, in order to attain the highest rate of photosynthesis for an individual plant on a cloudless day, the light strength should be 108klux or 2000 μmol/m2s. The light intensity at which the rates of photosynthesis and respiration are equal is referred to as the light compensation point (LCP). This condition fulfils the basic living conditions of plant survival without additional energy for growth. The normal LCP for shade-oriented plants is about 10μmol/m2s, and the LSP value is 60～199μmol/m2s [1]. In general, photosynthesis takes place during the day. The number of photons received in one day is called the DLI, which is a common index for determining the light quantity and duration in a 2 particular area. DLI is measured in mol/m d (the 2 number of moles of photons per square meter (m ) per day (d), and its values vary depending on latitude, weather, clouds conditions, artificial structures, and so forth. In the northern part of the America, the maximum outdoor DLI is about 60 mol/m2d on a cloudless day in summer, but DLI may be less than 5 mol/m2d in winter [2]. In a large open space within a building, light may be blocked by structure depending on the sun's zenith angle, and therefore DLI varied at each lot. Lam gathered regression data from many investigations, indicating that solar radiation and sunshine duration are linearly correlated [3]. Based on this idea, the different values of solar radiation in a specific site can be estimated according to the duration of sunlight measured in each district [4], and the concept diagram of this approach is illustrated in Figure 1.

（1）The ratio of building height to the atrium is between 1:3 and 1:4, which is suitably human-scaled and appropriate for people’s activities, generating neither a feeling of oppression or loneliness. This may be a helpful reference for future lighting design. （2）The building to the north blocks the strong north wind, thereby reducing the impact of wind from the north on the plants. This is helpful for observation and discussion of sun exposure. （3）All buildings are simply-shaped, rectangular with balanced distribution among their surfaces. The building elevation opening ratio is close to 1:1 and will not vary significantly during the investigation.

2.2. Investigated Periods PAR measurements were conducted over four days in 2009, namely on Oct 24th, Oct 31st, Nov 7th and Dec 20th. More measurements were conducted in 2010 for further analysis, namely on Sept 24th, Sept 30th, Oct 7th, Oct 11th, Oct 12th, and Oct14th. The main reason for doing so on these dates is that after summer, the temperature and lighting decrease dramatically and the shadow distribution of the buildings becomes more evident, and these factors facilitate the discussion of the issue at hand. 2.3. The instruments The data logger employed is Campbell’s CR1000, with Delta OHM’s Probe LP PAR 01 as a sensor. Data is recorded each minute. 2.4. Planting Distribution and Mapping 2

The surrounded open area amounts to 2288m (44m×52m). Plantings in the site include 10 different types of trees (39 in total), and 3 different types of shrubs.

3. ATRIUM SUNLIGHT SIMULATION 3.1. Atrium Coordinates and measured point location The atrium is divided into 2m× 2m square lots to conduct investigation on the effects of lighting on various plantings, as shown in Figure 2. The instruments are set up at coordinate M04, at a location least impacted by buildings or planting. Test height is set at 100cm, approximately the height of the shrubs.

Figure 1: Concept diagram of DLI mapping procedure

2.1. Site condition The campus atrium of the National United University (120.75 E, 24.54 N) was selected as a simulation and served as the investigated site for this research. It was surrounded by three-story buildings on three sides, with an opening facing south. The south side was defined by a pedestrian walkway and a four-story building. Related conditions are listed as follows: Major reasons for the case choice:

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Figure 2: The atrium coordinates and measuring points location

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

3.2. Simulation and Calibration

cloudless day. However, the highest number of sunshine hours in the atrium is 12, and the lowest is 2. Examining the conditions of plant cultivation in the atrium, Pinus thunbergii Parl placed next to the North building would result in the lowest number of sunshine hours, RSH are only 22%-37%. Nevertheless, there are 44% for three Araucaria excelsa R.Br, which are 5m away from the North building. The other one Araucaria excelsa R. Br.located in the south of the atrium would receive 74% per day, the RSH would have made a difference 30%. In contrast, the sunshine hours of Phoenix loureir Kunth placed in a south-north orientation would be more equal than Araucaria excelsa R. Br.and Pinus thunbergii Parl, placed in east-west orientation.

Three user-friendly and widely-used simulation software packages were used in this study: (1) Ecotect 5.6, (2) Sketch Up 7, and (3) Auto CAD 2008. These software programs can allow us to conduct three-dimensional visual analysis based on building shadows. The software allows us to cross-reference their accuracies, as well as the precision of the data obtained. After building models are completed, the location, longitude, latitude, and simulation period are set in order to calculate the number of lighting hours in the atrium based on map overlay. The definitions of terms specific to sunshine hours are listed as follows: Possible duration of sunshine: Measure the time duration on a day when sunshine is on the ground. Duration of sunshine: Refers to the actual amount of time within a day when the sun directly shines on the ground. Rate of sunshine (RSH %): Refers to the ratio of the duration of sunshine to the possible duration of sunshine. RSH (%) = duration of sunshine hours/possible duration of sunshine hours Relative RSH (RSH’ %) = duration of sunshine hours/ possible duration of sunshine hours for a reference point.

     

Table 1: RSH (%) of Summer solstice& Vernal / Autumnal equinox& Winter solstice

3.3. RSH(%) of vernal/autumn equinox, summer solstice, and winter solstice. The results of light environment simulation on the vernal/autumn equinox, summer solstice, and winter solstice of the campus atrium were listed in Table 1, and shown in Figure 3-5. We briefly reviewed the results as follows: 1. Vernal/autumn equinox: There are 12 hours of sunshine hours on the vernal/autumn equinox in unshaded conditions. In the atrium, the highest number of sunshine hours is 9 hours, and the lowest is 4 hours. If plant cultivation is arranged in an eastwest orientation rather than in a south-north orientation, the RSH of Phoenix loureir Kunth would have made a difference of 25% per day.

  Figure 3: The distribution of RSH on Vernal /Autumnal equinox

2. Summer solstice: With unshaded conditions, there are almost 13.58 sunshine hours on a

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

4. INVESTIGATED RESULTS OF PAR AND DLI VALUES

Figure 4: The distribution of RSH on Summer solstice

3. Winter solstice: 10.51 hours of sunshine hours were estimated on the winter solstice in unshaded conditions. 7 hours and 0 hours are the maximum and minimum number of sunshine hours per day in the atrium, and 0 hours of sunshine per day is number for the so-called complete shadow region. At present, the complete shadow region is the pathway, and there is one hour of sunshine per day near the pathway. Three Araucaria excelsa R. Br.on the north side of the atrium enjoy 57-66% per day; however, the other Araucaria excelsa R. Br.on the south side only receives 19% sunshine per day, the exact opposite of the conditions on the summer solstice.

 

According to references [5], the DLI value can be calculated as follows: DLI (mol/m2d) = 0.0864×average daily PAR (μmol/m2s) The DLI of each lot in the atrium can be obtained by measuring the PAR value of a reference point and mapping the sunshine hours. We can observe that the DLI values varied significantly with the seasons as shown in Table 2. Furthermore, the difference in relative sunshine hours previously mentioned, that is, the amount of light received by the plant in each lot, actually varies greatly within a small investigated area. We measured the PAR of the reference point on 2009 September 24th, and converted the daily 2 average value 196 μmol/m s into the DLI. Based 2 upon the results 17 mol/m d the appropriateness of plant design on campus in terms of their reaction to sunlight conditions could be examined. On the autumnal equinox, the SH ranges from 4 hours to 9 hours, and the DLI gap is 7.14 mol/m2d. If the summer solstice daily average value reaches 50 μmol/m2s, SH ranges from 2 hours to 12 hours, then the DLI gap will almost reach 36.5 mol/m2d. This gap reveals that the rate of photosynthesis decreases if we do not estimate the shading conditions of the plants precisely, resulting in increased plant maintenance costs.

 

Table 2: Investigated PAR 2 converted to DLI (mol/m d)

2

(μmol/m s)

and

Figure 5: The distribution of RSH on Winter solstice

We observed that the plant most influenced by the change of sunshine hours in winter is Phoenix loureir Kunth, located within range X01-X19, and placed in a south-north orientation. Especially, eight of Phoenix loureir Kunth three of whose distance is within 10 meters, had RSH varying from 9%-57%. Consequently, only high light tolerance plants are preferable for cultivation in this area due to the obstruction of light for the buildings.

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5. RELATIVE DLI DISCUSSION

MAPPING

AND

The atrium plantings can be divided into eastwest and north-south plantings, based on their distribution. The east-west plantings are 1, 5, and 13 meters from the north building, respectively. Based on the number of sunshine hours, the following was found in Table 3: 1. The DLI of the 4 Pinus thunbergii Parl on the winter solstice are 11-16. Although they are located

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

in the southern section of the building, they are too close to the building. Thus, the lighting conditions are relatively poor, and the tree crowns only receive sunshine from one direction. These circumstances have resulted in rather sparse Pinus thunbergii Parl, and as a consequence of the phototropism effect, in branches of Pinus thunbergii Parl-3 being bent 45 degrees, exhibiting “sick landscape syndrome.”

 

2

Table 3: Relative DLI (mol/m d) of plants

than the DLI value of 16 of the other three Bauhinia variegata Linn on the western side. 4. Twelve Phoenix loureir Kunth form two rows of plantings on the north-south. On the equinox, the DLI diagram clearly indicated that the four on the western side of the atrium have significantly higher values than the eight on the eastern side. However, on the winter solstice, the DLI value increased sharply from 2 to 16, creating an environment with greatly varying lighting conditions, as shown in Figure 6.

Figure 6: DLI map of the atrium on the winter solstice

 

Reading the shadow map allows one to deduce that the shrubs in the circular central flowerpots cannot grow freely. The rhododendron will not reach its expected full blossom and is being displaced by the duranta repens growing. However, this shift is resulting in great aesthetic disharmony, demonstrating that the varying effects of lighting are directly manifested in the density of shrubs. Overall, the environment of the atrium unsatisfactorily fulfils the requisite nurturing conditions in terms of its symmetry or geometric design, particularly in the use of a fixed flower bed.

 

6. CONCLUSION

  2. Three out of four Araucaria excelsa R. Br.are located five meters from the north building, but due to mutual shading, the actual sunshine hours are lower than in the simulation data. In particular, Araucaria excelsa R. Br.-4 is planted on the southern side of the atrium, which receives significantly lower amounts of sunshine compared to the other three Araucaria excelsa R. Br.on the winter solstice, with a DLI value of 5. This value stands in stark contrast with the DLI values of 14 to 16 of the other Araucaria excelsa R.Br. 3. Three out of four Bauhinia variegata Linn are located on the eastern side and have a DLI value of 9 on the winter solstice, a value significantly lower

Generally, climate data provides the general sunlight duration throughout a city [6], failing to recognize the precise microclimates that are critical for plant installation design. The assumed sunshine conditions derived from meteorological observation stations using interpolation do not provide the information required on the microclimate scale. However, long-term quantum flux data captured in the greenhouse cannot be applied to numerous construction sites that require greening. Therefore, computer simulation should be conducted before greening design in the future. From a long-term perspective, studies have indicated that plant shadows can reduce the heat gain of buildings and have also demonstrated that their effects manifest themselves differently according to climate [7,8,9]. In contrast, no readily available investigation has focused on the impact of building shade on nearby plants. However, such a

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

study could prove to be a valuable reference in plant design [10]. In the future, landscape design would do well to incorporate “live” elements by employing a more scientific and quantitative method to enhance the survival rate of plantings, as well as to provide a “comfortable” environment. Taking such measures would ensure the aesthetic value of the landscape and fulfil the goal of sustainable energy conservation. Taking visual effects as well as the rate of sunlight into consideration, “symmetric” or “row” plant designs usually neglect the fact that plants are living organisms. Unlike statues, electric lights, chairs, ponds, and so forth, plants grow and change as time passes. Gardening is a living art. When visiting the same place after decades, the trees will have grown taller or will have withered away, creating new visual effects. In seeking to produce “comfort zones” for human beings, we should also understand the comfort zones necessary to plants in order to establish a mutual-beneficiary environment for plants and human beings [11].

7. REFERENCES [1] J. Janick, Light , Horticultural Science (1986), 253. [2] E. Runkle, Technically speaking: Daily light integral defined, Greenhouse Product News (2006) ,16. [3] J.C. Lam, D.H.W. Li, Regression analysis of solar radiation and sunshine duration, Architectural Science Review (1996), 15. [4] C. H. Lin, D. L. Ling, and Y. S. Chang, Visual ecology: Outdoor light environment for plant design by using computer simulation. Building Environ (2007) , 42. [5] E. Runkle, Technically speaking: Do you know what your DLI is? Greenhouse Product News (2006) ,16. [6] P. C. Korczynski, J. Logan, and J. E. Faust, Mapping Monthly Distribution of Daily Light Integrals across the Contiguous United States. HortTechnology (2002) ,12. [7] A.W. Meerow, R.J. Black, Enviroscaping to Conserve Energy: Determining Shade Patterns for South Florida. Univ. of Florida: Food and Agricultural, Inc.（1993）, Circular EES-48. [8] J.C. Lam, Shading effects due to nearby buildings and energy implications. Energy Conversion ＆ Management. (2000),41 [9] V. Olgyay, Design with Climate: Bioclimate Approach to Architectural Regionalism. New York: Van Nostrand Reinhold (1992), 74. [10] C. H. Lin, D. L. Ling, and Y. S. Chang, Make reasonable decisions for greening plan：effects of distribution of shading duration by building structures, Design & Nature 2, UK: WIT press (2004), 73. [11] C.H. Lin, D. L. Ling, Y. S. Chang, Enviroscaping and Sunlight Design: An Energy-based Study of Plant Design by Calculating Sunshine Duration, The 41st IFLA World Congress, Taipei. (2004),710

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The Visual Environment in the vernacular dwellings at Mount Pelion, Greece Natalia SAKARELLOU-TOUSI 1, Benson LAU 2 1,2

School of the Built Environment, University of Nottingham, Nottingham, United Kingdom

ABSTRACT: This paper explores the visual delight created by the appropriate and sensitive use of unique architectural features of a particular type of vernacular dwelling to provide the desirable luminous environment. They are contained on a well-preserved mansion located in Vysitsa village (39°19N and 23°09E) at Mount Pelion in Greece, which reserves all architectural elements of the Greek traditional mountainous architecture, playing the role of a typical representative model. For the understanding the design of the internal luminous environment, both daylighting and sunlighting behaviour inside the building is investigated, the quality and the quantity of light is examined and the effect of specific architectural elements to control the natural light for achieving desirable lighting conditions and visual comfort is tested in different seasons, days and times by conducting field measurement, physical model testing as well as computer simulations. In addition, the corelation between the occupants’ social activities background, seasonal migratory living patterns, the needs for environmental comfort and the quest for light has been critically analyzed. The derived conclusions of this study identify the lighting control techniques used to achieve the ingenious bioclimatic adaptation of this particular type of vernacular building to the external climatic conditions and the daylight and sunlight availability. Keywords: Climatic responsive design, daylight, visual comfort, migratory living patterns

1. INTRODUCTION The light in the Geek mountainous traditional structures, examined in this analysis, plays the role of a “boundary”, aiming occasionally to the connection or separation between the indoor and outdoor spaces [1,3]. The design of these mansions is based on the harmonic interaction of the historical context and occupants’ visual needs. Two basic controversial issues- Defence and protection from predatory raids and frequent conflicts that accompanied the establishment of Ottoman rule and need of adequate illumination light according to the room type, use and occupation frequency- created a unique habitat, mainly based on the builders’ accumulated experiences. The fenestration design aims to unify and differentiate the rooms, according to the occupants’ activities and visual needs [2,3]. The design which integrates all the social, cultural and climatic characteristics of this area in mountainous Greece, provide exemplary design guidelines and valuable references for modern designers. 1.1. Case study

Fig.1: Mansion external and internal views - Public and private zones.

The under investigated L-shaped Mansion is orientated in a deviation of 27° from due North to East, having a view to the Pagasic Gulf. This house built in 1791, which is now used as a guesthouse, still retains all the typical characteristics of Pelion vernacular architecture. The building has a ground floor and two storeys above connected by a narrow wooden staircase, which enables the vertical circulation of the occupants. All storeys have the similar layout and each floor is separated into two zones: the public zone (living rooms, sitting rooms and kitchen) which is in the southwest and has the advantage of a good view and orientation to the sea and the private zone (bedrooms and bathrooms), which is in the northeast and is protected by the steep mountain slope (Fig.1). The ground and first floors have very thick external and internal stonewalls, which play a fundamental supporting role with very few windows. The first floor is called with an introvert character

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directly related to occupants’ winter activities, visual and thermal needs and to its defensive historical role. The internal environment is dimly lit. In stark contrast to this “winter accommodation”, the second floor is a combination of lightweight and heavyweight construction and is normally used as the “summer accommodation” with an extrovert character and relatively brightly lit luminous environment. The private zone here is a heavyweight construction, same as in the lower storeys and the public zone is a lightweight construction, punctured by numerous windows. There is no obstruction that overshadow the mansion, or block its view to the sea [4,5,6]. 1.2. Research Methodology & limitations In this study, in order to understand the daylighting and sunlighting performance in the building, different analytical tools have been used to study the luminous environment. These tools highlight the role of this mansion’s typical architectural features in terms of lighting control and visual comfort.

2. DAYLIGHTING AND SUNLIGHTING PERFORMANCE ANALYSIS 2.1. Climate In general, the climate in Mount Pelion is moderate during the summer (27°C-30°C) and cold during the winter (-5°C-4°C). During the summer months there is an average of 11 hours of daily sunshine on Mount Pelion, and during the winter months there is an average of 4 hours/day. The overcast sky illumination in this area is as follows [7]:

The solar altitude is very steep: 79• in summer solstice, 57• in equinox and 32• in winter solstice [8]. Thus the key environmental consideration in this climate is to control the solar radiation in order to provide passive solar heating during the winter months and to prevent the building from overheating during the summer months, through adopting specific envelope designs and window apertures. Due to the low temperature during the winter, thermal comfort was the primary concern for the occupants [5, 7]. 2.2. Typical Architectural Elements and their impact on the internal luminous environment

Fig.2: Photographs of the physical model: Artificial Sky and Heliodon laboratories

The conclusions and results of the daylight and sunlight analysis are obtained through the following means: 1. Field measurements taken in June 2008. Generic observations and monitoring results were obtained due to the relatively short research time scale. Nevertheless, the results are very close to reality. Additionally, the onsite measurements consider both sunny and overcast sky conditions. 2. Physical models, tested in Artificial Sky to investigate the internal luminous environment in terms of daylight levels and distribution. 3. Physical models were also tested on Heliodon to explore the solar ingress. 4. Three dimensional computer simulations of the buildings, through the use of Ecotect and Radiance software for quantitative assessment. The properties (i.e. reflectance, roughness, brightness and colour) of the materials used in the simulations are similar to the reality. The external illuminance used is 7000 lux (overcast sky in Greece in December) as a worst case scenario is tested. 5. Interview with the owner and visitors have been conducted on site to support the quantitative studies.

The key architectural features of the mansion, which control the light, are the followings (Fig.3) [5]: A. Roof overhang: summer accommodation (public and private zone) B. Wooden shutters: in summer accommodation (public zone) C. Clerestory fixed windows: in summer accommodation (public zone) D. Small splayed reveal windows and wide windowsill and lintel of the thick walls (in the entire ground floor and winter accommodation and private zone of the summer accommodation).

Fig.3: Key envelope architectural features of the mansion

Analysis: A. Roof overhang: summer accommodation (public and private zone)

The eave of the roof is extended beyond the wall of the summer accommodation (second floor) about 0.7m. This acts as an overhang, and provides

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additional protection to the lightweight east, west, and south facades from the intensive solar radiation in summer and the frequent rain and snowfall during winter. It can be observed that in summertime the overhang of the roof plays a very important role, shadowing the second floor, whilst in mid-season and winter, instead of blocking out the sun, it allows direct solar ingress and provides beneficial solar gains to the communal southwest rooms.

northern bedrooms and the external very luminous environment. It is important to mention that the shutters are solid and not louvered, because they also act as a wind barrier, compensating simultaneously the occupants’ thermal needs; prevention form overheating during the summer and minimisation of the heat losses during the winter. Based on the computer simulations, the summer’s accommodation internal daylight levels in the public zone are adequate and the daylight distribution is quite even, to provide desirable visual comfort (Fig.5c). The onsite measurements, taken in summer (morning and afternoon), show that the public space of the summer accommodation is very luminous whereas the daylight distribution is uneven. The daylight factor and the Uniformity Ratio of these spaces are as follows:

Fig.4: Roof eave - Detailed diagram of sun penetration and sun shading in summer solstice, equinox and winter solstice B. Wooden shutters: summer accommodation (public zone)

Fig. 5: a. Wooden shutters of the summer accommodation, with various levels of openness. b. Detailed diagram of sun penetration and sun shading in three key days. c. Summer accommodation daylight distribution (computer simulation)

On the second floor, the public zone is exposed to the sun on two most vulnerable facades: the southwest and the northeast. The envelope, which is pierced by nineteen large apertures and multicoloured clerestory windows, indicates the need of the occupants to live in well daylit but controllable luminous environments, mostly in summer and midseason. To protect the communal spaces from overheating and very high internal daylight levels, the windows of the public zone are protected by wooden shutters which are separated into three parts (two vertical and one horizontal) (Fig.5a, 5b). Each part can be moved independently, so as to provide the occupants with the opportunity to adjust it (rotating and fixing one, two, or all parts of the shading devices) according to their needs and comfort level, as well as to the climatic characteristics of each season (solar altitude and light intensity). This gives the occupants the ability to convert the room from a relatively dark enclosed area into a semi-outdoor one. These rooms thus function to provide an intermediate adaptation zone between the very dark

It should be pointed out that these measurements take into account not only the diffused but also the direct light. The uneven distribution can be explained by the fact that the external illumination is very high and the flimsy walls with the numerous big apertures create a very bright zone close to the window, which causes a great contrast between this area and the back of the room. In addition, the second floor’s flimsy envelope protected by the three-part opaque shading devices partly blocks the incoming light, creating “fragments” of light patches in the rooms (Fig.7). The Artificial Sky testing shows adequate daylight levels but the daylight distribution is not even. The second’s floor summer accommodation public space consists of a living room and a formal room. The results for these two spaces are as follows: Living room: DF: 3.6% and UR: 0.1, Formal room: DF: 2.8% and UR: 0.16. It should be noted that for internal dwellings/hotel spaces, the adequate DF% levels are the following [living rooms: 2%, bedrooms: 1.5%, kitchen 2% [7]. As for the uniformity ratio, above 0.5 indicates a relatively even lit internal environment, while 0.2 shows uneven light distribution. C. Clerestory fixed windows: summer accommodation (public zone)

The height of the public zone in the summer accommodation is greater than that of the other storeys. It varies from 3m to 6.50m where the roof is internally exposed. Above the large numerous windows, multi-coloured clerestory windows are placed. These windows are designed to provide diffused light on the upper part of the wall of the room, preventing from glare vertically and to smooth the daylight distribution of the room in plan, by increasing the daylight levels at the back; only diffused light is provided during the equinox and summer because the roof eave blocks the direct

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light. Both diffused and direct light is provided during the winter months (Fig.6).

It should be taken into account that in this simulation no direct light is considered and the shutters are not fully open. D. Small splayed reveal windows and wide windowsill of the thick walls (ground, first and second floor)

Fig.6: a. Clerestory fixed windows, b. Detailed diagram of sun penetration through the clerestory windows in three key days

A comparative study has been carried out to prove the significant role that the clerestory windows play in enhancing the luminous environment: Qualitatively by using Heliodon and quantitatively by carrying out computer simulations. From the Heliodon testing it is obvious that the upper part of the front wall is always brighter where clerestory windows are introduced (Fig.7).

The ground and first floors (winter accommodation) have very thick external stonewalls (0.9m-1m) and internal stonewalls (0.5m-0.7m) with very few and small windows, for historical defensive and thermal comfort reasons. Wooden shutters, which open internally, keep out the sun and the cold or hot winds when necessary (used for keeping the heat in or minimization of heat losses). All of the openings on the ground and first floors and the ones in the private zone of the second floor (bedrooms) are either simply rectangular, or rectangular with “clam-shaped” lintels (Fig.9).

Fig. 9: a. Splayed reveal windows with internal shutters b. Detailed diagram of sun penetration and sun shading through the small graded reveal windows in three key days.

This design highlights the priority in the winter accommodation to minimize the heat losses and to protect the occupants from the invasions. Therefore, by this introvert and firm construction visual comfort was not easily achievable (Fig.9a). Thus, this design has the potential to reduce the solar gains in winter and to make the rooms very dark and gloomy.

Fig.7: Heliodon solar study (perspective of the living room) with and without clerestory windows in equinox.

Comparing the existing living room of the summer accommodation (with the clerestory windows) with the hypothetical case (without clerestory windows), the computer simulation results show that- even thought in both cases the living room is not adequately illuminated- in the existing scenario the internal daylight levels are numerically greater and the daylight distribution more even (Fig.8). Fig.10: Daylight distribution of the winter accommodation (computer simulation)

Fig.8: Living room with and without fixed clerestory windows in plan.

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From the computer simulation results shown in Fig.10, it is evident that visual discomfort occurs due to uneven light distribution which leads to poor uniformity. This is explained by the fact that the thick walls with the very small and few windows block the light considerably and, even though the external illumination is high, only a small portion of the available natural light can enters the rooms.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The results from the field measurements, taken in summer (morning and afternoon), show that all the winter’s accommodation rooms are considered almost gloomy, with a very uneven daylight distribution. The very high external illumination, which is testified also in the computer simulation testing, improves the overall internal natural light levels but greatens the contrast between the area close to the windows and the back of the room, causing glare. Direct sunlight aggravates the glare occurrence. The monitoring results are summarised as follows:

configuration of the apertures improves the visual discomfort. A sample room of the building is tested to demonstrate the importance of this window configuration quantitatively (Fig.12). A luminance ratio less than 1:10 shows that glare is not a problem and that the contrast between the glazing unit and the wall is acceptable for the occupants’ visual comfort. Indeed, in all tests the splayed reveal improves both the internal daylight levels and distribution and lowers the brightness contrasts between the glazing unit and the surrounding surfaces.

As for the Artificial Sky testing, the rooms are also very gloomy, whereas the daylight distribution is slightly smoother than in the reality. The testing results are as follows:

The occupants in the past had as a priority the winter accommodation to provide them safety and thermal comfort. However, to reduce the risk of glare occurrence, the window’s reveal is made in a splayed form to reduce the excessive contrast between the glazing unit and the internal wall’s brightness. The occupant’s perception is that visual discomfort is reduced while looking at these rectangular or rectangular with “clam-shaped” lintels windows, by the intermediate splayed reveal, which provides graded contrast between the dark wall and the bright external illumination and greater internal daylight levels. The following Heliodon study shows qualitatively the effective role of the splayed window reveal (Fig.11).

Fig.12: a. Brightness contrast comparative study (without and with splayed reveal windows): Artificial Sky (diffused light) and Heliodon (direct light). b. Daylight distribution comparative study (without and with splayed reveal window in plan): computer simulation.

On site measurements are taken also to test the glare occurrence. Three representative windows of the three storeys of different orientations are showed below (Fig.12).

Fig.11: Heliodon solar study (perspective of kitchen on the ground floor) in equinox.

It should be noted that this is a simulation that took place in a laboratory with only one light source representing the sun. No diffused light is taken into account and therefore the contrast here looks greater than reality. In reality it is assumed that the diffused light lowers the contrasts. In equinox, because of the small size of the windows glare is observed in specific surfaces and hours of the day, but the

Fig.12. On site measurements; brightness contrast testing for glare occurrence

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On the ground floor kitchen southwest windows glare problem occurs, which is partly explained by the fact that a brown wooden cladding has been applied around the glazing units of the window. The colours of the surfaces that surround the glazing unit play considerable role to the glare occurrence, since the colour is related to the brightness of a surface. In terms of sunlight penetration, the thick walls (the internal part of the sill and the external part of the lintel of the windows) were carefully designed to shade the openings during the summer and equinox, but not to block the sun during the winter (Fig. 9b).

3. CONCLUSION Evaluation of the Vernacular Architecture in Terms of Natural Light The design, location, and size of the windows in this typical vernacular dwelling at Mount Pelion in Greece are based on the solar and wind vulnerability of each facade. The design of the fenestration responds well to the functional and light requirements of the communal and private spaces. Most of the openings are placed on the southwest facade (the front) for receiving the sun’s radiation and fewer on the northeast facade (the back) for reducing the heat losses (northeast facade) in winter. The roof overhang, the three-part shutters of the summer accommodation and the window sills of the apertures of the ground floor and the winter accommodation, contribute to the successful solar control of the mansion during the summer and mid season, especially for the southwest facade. However, in most of the mansion’s rooms daylight illuminance varies according to the function of the rooms. Light level is low in the bed rooms, but relatively high in the communal spaces. Although the small openings in the “winter accommodation” tend to create high brightness contrast between the peripheral zone and the back zone of the rooms at times, the splayed window reveals of the masonry walls and the clerestory fixed windows of the second floor’s public zone, effectively contribute to the deeper light penetration and contrast grading within the structure. As a result, the adverse impact from the discomfort glare is reduced. As for the glare occurrence, from the onsite measurements it can be concluded that on the southwest facade (the front), which is the most vulnerable facade because of direct excessive solar radiation, glare is a problem at times. On the northwest and the southeast facades fewer problems with glare have been observed; the northwest facade (the back) does not receive much solar radiation, and therefore has no problems with glare. In early summer, when the measurements were taken, excessive brightness contrast was observed only in the lightweight construction of the second floor and the very dark northwest bedrooms of the ground and first floors. It can be assumed that glare will be more intense during the winter, when the sun altitude is much lower. However, the provision of shutters, splayed window reveals and clerestory windows allow the users to control their internal environment.

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The lesson learnt from this vernacular structure is that the size, type and the amount of openings and shading devices on each fa• ade were constructed according to the seasonal activities of the occupants in each room, and the social contexts in which they were living in the past. Basically the fenestration design respects the migratory living patterns of the occupants. Based on the function of the rooms (e.g., bedroom or living room), different quantity and quality of natural light is provided. All bedrooms of the building have only one window because of their individual use and the resting activities (i.e. sleep, get dressed or rest), meaning that they needed little natural lighting (private zone). Whereas the living rooms of the second floor, where people gather and spend time together have many apertures because of their use for work or communal activities, meaning that they needed brighter spaces. Therefore, the bedrooms were designed to be gloomier and the communal spaces to be more luminous. Furthermore, the occupants used to stay in the winter accommodation during the winter months and in the summer accommodation in the summer months (seasonal migratory living pattern) [4], so the luminous environment is in tune with this internal migratory living pattern. Additionally, it should be taken into account the priority for thermal comfort and the defensive role that the winter accommodation played in the past. Therefore, the visual delight was not the primary concern on the ground and first floor. Thus, the social needs and the daily and seasonal activities dictated the building envelope design, the materials, and the placement of apertures on different facade. This vernacular dwelling is an exemplar precedent for demonstrating how building design can respond to the seasonal needs of the occupants in terms of visual comfort and delight.

4. REFERENCES [1] Moore F., Concepts and Practice of Architectural

Daylighting, Van Nostrand Company New York, 1985

[2] Millet S. M., Light Revealing Architecture, John Wiley & Sons, Inc., 1996 [3] Baker N., Steemers K., Daylight design of Buildings, James & James , 2000 [4] Sakarellou-Tousi N., Lau B., The Vernacular Dwellings of Mount Pelion in Greece: A migratory living pattern, PLEA Conference, Architecture Energy and Occupants Perspective, nd th Quebec City, 22 -24 June 2009 [5] Kizis Y., Mount Pelion Constructions (in Greek Language), Cultural Technological Institute, 1994 [6] Leonidopoulou – Stilianou R., Greek Vernacular Architecture, Pelion, Melissa, 1992 [7] Tsipiras T., Tsipiras K., Ecological Architecture, Kedros, June 2007 [8] http://www.hnms.gr

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The poetics of contemplative light in the Church of Notre-Dame-du-Haut designed by Le Corbusier Dimitris KAIMAKLIOTIS1, Benson LAU2 1,2

Department of Architecture and Built Environment, Nottingham University th

Abstract: Le Corbusier was one of the most influential architects of the 20 century and his built structures and writings have become the sources of inspiration for practitioners and students. As Le Corbusier wrote: “Architecture is the masterly, correct and magnificent play of volumes brought together in light”. Daylight was one of the key design elements which Le Corbusier used to illuminate and dramatise the space and form, and to evoke special luminous environments which are appropriate for the programme and function of the building in order to enhance and enrich the spatial and visual delight in architecture. The objective of this paper is to investigate the poetics of the contemplative light which one can vividly experience in the Ronchamp chapel. Through on site monitoring and physical model testing, the lighting techniques which Le Corbusier adopted in this Chapel to define the collective and individual light in this sacred structure were qualitatively and quantitatively analysed. This study concluded that Le Corbusier’s skilful orchestration and manipulation of adaptive light, building fenestration, window aperture and the sacred form have led to a poetic luminous environment where both dynamic and static luminous balance co-existed in a harmonious manner. Much can be learnt by studying Le Corbusier’s religious buildings which were built by using daylight as the primary light source and the built form as the solar clock to register and respond to daily arc of the sun. Detailed analysis on the contemplative light created by Le Corbusier in the Ronchamp Chapel would provide valuable insights and data which can be applied to the more routine design of the luminous environment. Key Words: Spatial poetry, adaptive light, sacred realm

1. INTRODUCTION 1.1. History

Ron champ Chapel, one of the most influential buildings of modern architecture, is Le Corbusiers autobiography. It is the confession of his true nature as an artist, although being an architect he was also a prolific painter and sculptor. The result of such versatile skill was the creation of a chapel at the top of the Notre-Dame-du-Haut hill in East France near Ronchamp village, 20km from Belfort, on the way to Vesoul. Ronchamp Chapel was one of the three religious buildings ever designed by him. The Chapel of Ronchamp and the Monastery of La Tourette were built during his lifetime while the parish church of Saint-Pierre was completed in 2006, 41 years after his death by French architect, and Le Corbusiers student, Jose Oubrerie. In 1950 the manager of the photographic archives of France, the director of the museum of decorative arts in Paris and Canon Lucien Ledeur from the seminar of Besanon on the recommendation of Father Alain Couturier of Lyons approached Le Corbusier and asked for his help as he was well known for his design freedom and free play of expression. Le Corbusier was neither a religious extremist nor an atheist as he was raised as a protestant with both his Aunt and Pauline being devout. Bearing in mind the sensitivity of different religious identities in the 1950s, Le Corbusier when asked about his design intentions at Ronchamp he

replied: " I have not experienced the miracle of faith, but I have often known the miracle of ineffable space..."[1]. After five years of design and two years of work, on the 25th June 1955, the chapel was finally inaugurated. This paper is not intended to criticise or find faults but on the contrary, it is an appreciation of adaptive light inside a sacred realm in the chapel of Ronchamp.

1.2. The Key is Light

Light has been a vital drive for Le Corbusier in designing a space. He said that "Architecture is the masterly, correct and magnificent play of masses brought together in light..."[2]. Through his religious buildings Le Corbusier used light in different ways "the key is light and light illuminates forms. And these forms take on an emotive power [...]"[3] In this paper the author’s study will focus on Le Corbusier’s skilful manipulation of Adaptive Light in the chapel of Ronhamp. A significant attribute of the human vision is the ability to clarify between levels of light that vary from complete darkness to the vivid glare of a bright day. This phenomenon is known as adaptation and the mechanisms by which it occurs and its implications for building design have been the subject of much study [4].

1.3. Methodology

In order to understand the poetics of adaptive light in the Chapel of Ronchamp, the luminous environment had been analyzed both qualitatively and

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quantitatively. The qualitative analysis, involving tonal sketching and on site observations of the luminous environment reveal the techniques used by Le Corbusiers to achieve light adaptation within a sacred structure. In order to bring to life the light dramas through longer time periods, a detailed 1:50 scale model was constructed and tested under the Heliodon and Artificial sky. Furthermore, an animation has been composed by the authors to fully appreciate Le Corbusier's skilful orchestration and manipulation of light adaptations within the Chapel. All these information have been cross referenced by the quantitative analysis which involved spot measurements of the photometric data on site.

gradually rises as it reaches the end corner. The South Facade with its gently sloping wall holds the main entrance of the chapel.

2. LUMINOUS ENVIRONMENT IN THE RONCHAMP CHAPEL

Figure 1: The site, context and surroundings, Interior & Exterior Elevations, photos- from Kaimakliotis, 2008

2.1. The “Promenade Architecturale”

The way you approach, how you enter or exit, all perceive the architects notion of procession to a building, inspired by the Greek Parthenon on the Athenian Acropolis. Le Corbusier envisioned Ronchamp as a three dimensional sculpture to be admired from all perspectives and intended visitors to follow what he described as “promenade architectural", Of this journey he wrote: It is the “promenade,” the movements we make that act as the motor for architectural events [5].

2.2. Outside

The journey begins from the road linking Belfort with Vesoul as the white outline of the chapel starts to appear going up the hill. The adventure starts from the village of Ronchamp when the visitor takes a steep path and after arriving at the summit of path (figure 1) vision becomes shallower by the trees and bushes and then suddenly, "Outside: we approach, we see, our interest is aroused, we stop, we appreciate..." [6]. As usual, nature had a role in the design as there are various sketches of shells examining the way that outside surfaces become inside ones, and inside ones become outside ones.

2.3. Inside

One of the great accomplishments at Ronchamp is the precise planning of its various phenomena through time and space, to produce a totality of light in motion. A combination of white convex and concave sprayed concrete walls covered by a dark grey shell like roof, compiled by three towers, one being significantly taller than the others, make the Chapel. The architect used concrete because "concrete is a material that doesn't cheat...rough concrete says: " I am concrete.[7] The transition of light changes respectively as the earth rotates. The chapel's two main facades are oriented towards the South and East, separated by a pinched wall that

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In the interior of the chapel the use of different colours is dominant to the eye, from the roof to the concrete entrance and finishing with the painted windows on the south wall. Natural light is present in every space and form. Within the chapel there are three private praying spaces under the light towers where light can be classified as Individual Light; the open space where the nave is located can be classified as Collective Light. These two types of light within the chapel contribute to a well balanced luminous environment. The approach to each space is also vital for the architectural notion of light adaptations. In relation to the Individual light which occurs inside all the towers further testing will show how the balance of light occurs to the human eye. Within the Collective Light which covers the nave, East and South wall, further qualitative analysis will show how asymmetrical balance help create a static, yet dynamic luminous environment . The journey continues to the inside and as one enters the chapel from the North the attention is immediately drawn to the South wall, "the south wall provokes astonishment"[8], but also to the choir on the East, the East wall comes to life as the first light comes up. As one views the East façade, multiple light sources meet the eyes, a horizontal ray of light between the East wall and roof gives the impression of a floating roof, scattered holes behind the altar seem like stars in heaven, followed by a beam of light flushing through from the south east corner, and finally glimpses of natural light from the south wall openings interfere within the space as they naturally balance the scene.

Figure 2: East Facade, Physical model photo & sketch-from Kaimakliotis, 2008.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July2011)

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The asymmetrical balance of light created by this lightning technique enhances visual perception by eliminating excessive brightness and contrast[9]. In other words in order to prevent glare the architect used various light sources from different directions to interact on each other. The only point where glare occurs from the East facade is during morning hours were the Virgin Mary Statue is lit by the morning light. As this is the only point in the chapel were glare is observed. After thorough site monitoring, it seems that this was done intentionally by the architect. The importance of Virgin Mary in Christianity is seen through a brightly lit square aperture which produces high levels of contrast, in the chapel at specific points in time, symbolizing the divine light. Photometric measurements were taken on site as indicated in Figure 3. In the CIBSE code for interior Lighting (1994) and in Daylighting by Hopkinson, the suggested ratio of task luminance to immediate surround to general surround should be in order of 10:3:1 [10]. The strong contrast between a light source and its background can often create glare.

Aperture F, (figure 4) experienced glare. This was because at the specific time when the reading was taken, window F was directly facing the sun. All the openings are orientated in slightly different angles capturing momentarily the sun at different times of the day. Le Corbusier used this technique to gradually prepare one’s adaptation to the constantly changing light through the thick south wall and led the visitors to the next spiritual realm.

Figure 4: Luminance Contrast Study South Wall, top centre image from physical model-from Kaimakliotis, 2008.

Figure 3: Luminance Contrast Study (on site monitoring) for East, Virgin Mary Statue-from Kaimakliotis, 2008.

Inside the chapel a single statue of the Virgin Mary was displayed in the square window on the east wall and as mentioned above Le Corbusier intentionally emphasized its importance by manipulating the brightness contrast. The ratio calculated for the Virgin Mary statue, the immediate surround and general surround is 63:3:1, indicating high contrast ratio and the occurrence of glare (fig. 3). In the chapel three towers can be found, each represents an individual sacred space. All towers point at different directions but the third chapel extends from the sacristy in an east west axis capturing the rays of sunrise which become a holy spread as they encounter the tower's red walls. As the visitor encounters the more private and individual spaces within the chapel, luminance levels and light sources change accordingly but only within that specific space. This is an individual light within a collective space therefore it does not interfere with the luminous balance of the east and South facade. Moving away from the east facing tower, and as the rays of light within the east wall gradually dim out, the south wall comes to life, lighting up the deep splayed windows which capture the sun at a specific point in time. As time passes and the earth rotates around the sun different window apertures light up on the South Wall. After conducting on site monitoring,

Although facing South one can barely experience glare as the large thicknesses of the walls gradually diffuse light through, and at the same time the shell like roof acting as a canopy on the outside, blocks most light beams from the sun, especially during summer months. An effective technique used by the architect to block the direct sun beams from the outside without interfering with the inside and therefore creating a well balanced internal lighting condition. Due to varying positions of the sun, winter sun is lower, summer sun is higher, the luminous environment during both seasons changes dramatically with the winter season exposing the south wall to direct solar penetration.(figure 5) This is the only season when sun rays are allowed to penetrate into the chapel, to bring direct light and warmth to the nave.

Figure 5: Section through south wall, images from physical model showing how roof blocks the sun in summer-from kaimakliotis, 2008.

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As the South Wall gradually dims out to ambient light levels, and as the sun sets, the West facade takes on its turn to contribute to the poetics of contemplative light. In order to demonstrate the balance of light on the West façade, the architect used a combination of individual and collective light. The West facade is the only blind facade in the chapel but it is accompanied by the South Tower (figure 6), in a north/south axis receives the relatively constant north light through the calotte above it, the other tower aligned west-east axis lights the structure with the setting sun through its west facing calotte. Again the skilful lighting technique is clearly shown here as the two towers on the West facade create an asymmetrical balance which in turn enhancing the light adaptation.

Figure 6: Light Tower facing North, Graph showing light evenly dispersing down the tower-from Kaimakliotis, 2008.

Based on figure 6 we can observe how light is evenly distributed from the top of the tower to the bottom. Although human eyes operate over a large range of light levels. They need to adjust gradually to its surroundings. Le Corbusier managed to disperse light inside the tower which helps the human eye to gradually adapt to the relatively dark luminous environment. As the journey continues on the blind West facade from the North tower, attention is drawn to the smaller chapel as the sunset funnels light through the calottes above (figure 7). A more individual space with access only allowed by the priest. Again the architect managed to calm the human eye by providing only the necessary levels of light for light adaptation.

In order for the architect to achieve an asymetrical balance by introducing various light sources to balance the human perception of a specific place, much thinking and testing had been done. One of Le Corbusiers assoiates, Iannis Xenakis, a Greek architect / engineer was thought to have helped in the design and testing although the extend of his involvement in the design is unlcear. As shown on figure 8 a 1:50 model was built and tested on the heliodon in order to capture the dramatic luminous environment from sunrise to sunset. The model was also used by the authors in the artificial sky to observe how light filters through the building. Daylight factor was also calculated and compared with the onsite measurements. In order to understand how the architet managed to evenly disperse natural light throught various apertures of the chapel various tests have been carried out.

Figure 8: Physical model, Heliodon study-Kaimakliotis, 2008.

The daylight factor in the chapel of Ronhamp will be expected to be low since it is normal to have low illuminance levels in a church. Le Corbusier tried to control the light intensity but at the same time to balance the light inside the chapel (figure 9). a simple test was constructed to prove this. The onsite measurements for the daylight illuminance were taken when the North door was deliberately left open and then closed. The photometric data taken from the physical model were recorded with the door closed and a comparison was made. A 1mx1m virtual grid was mapped on the floor plan to help derive the daylight distribution pattern under overcast sky conditions.

Figure 7: Physical model photo showing entrance to West facing tower, photo inside tower-Kaimakliotis, 2008.

2.4. The quantitative analysis of the adaptive light in Ronchamp chapel

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Figure 9: 3d model, light entering the chapel from all directions-from Kaimakliotis, 2008.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

and the results can be clearly seen on the matrix (figure 13). Light on the key dates like Winter solstice,

Figure 10: Daylight factor Door open: 0.6%, uniformity ratio 0.23 % ( on site measurements)-from Kaimakliotis, 2008.

Figure 11: Daylight factor with north door closed, uniformity ratio 0.3 %(artificial sky)-from Kaimakliotis, 2008.

Daylight Factor came out to be as low as expected. This is normal for a sacred place like Ronchamp because a more tranquil and meditative luminous environment is needed. However the Daylight Factor is double the value when the north door was left open (figure 10). Ronchamp has many window apertures but because each one has a specific task towards controlling the light entering the space and in turn contributing to the poetics of contemplative light, one single door when opened would make a huge difference inside the space. This proves how the architect used various light apertures to bring in the light in different spaces. As we can see from the graph in figure 12 the red line indicates illuminance levels when door is opened and blue line when door is closed. It is important to point out how uniform the light levels are within the sacred space while the door is kept close. Uniformity, light adaptation, contrast grading and balance of light is the lighting techniques that Le Corbusier frequently used in this sacred structure. The Luminous environment on the South wall were tested by using the Heliodon and physical model

Figure 12: On site analysis with physical model comparisonKaimakliotis, 2008.

Summer Solstice and Equinox have been investigated by taking pictures using a high resolution webcam, every half an hour starting from 6:00 in the morning till 18:00.The luminous environment varies at different times and depending how one views the south wall different perspectives can be perceived. According to Figure 13 the most interesting season to visit the chapel is winter. In winter, the south wall has full exposure to the sun due to the fact that the sun’s arc is lower, and therefore light penetrates the chapel along the whole length of the south wall. For all seasons, the most revealing times of various luminosities are when the sun rises in the morning and when the sun sets in the evening. The poetry behind light exposure is controlled at specific times of the day. Quite cleverly the architect tried to keep the luminosity of the south wall relatively constant from about 11:00 o clock until 15:00 in the afternoon. This can be observed clearly from Figure 13. In the morning the East wall becomes alive, and as the sun sets, change in luminance levels can be clearly seen on the south wall and west facade (towers). Light does not change in a drastic manner, but in a rather gradual way. Light slowly fades away, proving how the architect managed to control the light balance inside this sacred place by avoiding high brightness contrast and glare. As the south wall provokes astonishment, it is at the same time an exhibition of the architect’s talent and techniques. It is particularly interesting to observe how Le Corbusier used the roof to partially shade the south wall in the summer. He allowed light to penetrate only through the first row of openings on the south wall. This explains the architectural poetics on the south wall besides the modulor. The south wall is 3.7 meters thick at the bottom and 50 cm thick at the top. The first row of openings on the south wall is wider than all the others as the architect used the thicknesses of the wall to diffuse light evenly through the space. Using a high resolution web camera, inside the north facing tower of the physical model, tests have been conducted to investigated how light is being

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

diffused accurately and achieving sufficient adaptation levels for visual comfort. From Figure 14 we can understand how the architect used multiple light sources to funnel light through the tower. If one light source is temporarily blocked (Figure 14-C ) then the contrast ratio increases dramatically to an uncomfortable levels, also reducing the light intensity through the tower (figure 14-1) tip the balance in the luminous scene. Image D and image 2 in Figure 14 shows all the light sources actively working together to create a well balanced luminous environment at the west end of the chapel.

Finally the poetry behind the contemplative light can be further explained by referring to Figure15. two interior views captured moments within the chapel showing how Le Corbusier used a minimum of two light sources within a scene to create asymmetric balance of light. If high degree of brightness contrast exists between the brightly lit opening and the darker surrounding, then glare will occur. But glare can be avoided by allowing natural light to enter a space from at least two directions. Also Le Corbusier rarely used direct light, light gets filtered as it enters the space by using various calottes, colored glass, wide aperture openings with splayed reveal, and thick walls, Le Corbusier achieved the dynamic luminous balance by allowing diffused and reflected light to enter the Ronchamp Chapel, thus providing desirable luminous environment for the visitors. This study demonstrates how light balance and adaptation had been skillfully considered and manipulated by Le Corbusier in the sacred realm.

Figure15: Physical model showing multiple light sources. Light sources partially blocked - from Kaimakliotis, 2008. Figure 13: The luminous environment, physical model-from Kaimakliotis, 2008.

4. REFERENCES 1. 2. 3. 4.

Figure 14: North ambient light inside the North facing towerfrom Kaimakliotis,2008

5. 6.

3. CONCLUSION Ronchamp is a light machine, a solar clock registers the movement of the sun in different seasons. Different light traps capture the sunrise and follow through to sunset. What is fascinating is that whatever the devices are on the outside; they mirrored on the inside. Glare is skillfully avoided within the chapel by using architectural elements like calottes, doors and splayed apertures. Thicknesses of walls also play a vital role in funneling light though the tapered South wall. As the roof design might have been inspired from a crabs shell, it plays a significant role for blocking out the summer sun and controlling the luminous environment inside Ronchamp Chapel.

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7. 8. 9.

10.

Curtis`, W.J.R. (1986) Le Corbusier: Ideas and Forms`, (Phaidon`, Oxford).p.179. Le Corbusier. (1923). Translated by Etchells`, F. (1989). Towards a New Achitecture. Butterworth Architecture`, London`, p.31. Le Corbusier. (1957). Les Carnets de la Recherche Patiente no. 2`, p.27. Lewerentz`, S. Architecture of Adaptive Light`, Essay 6. Le Corbusier.(1936)`, Architecture Vivante :7. Le Corbusier.(1936)`, " Les tendanes de l``arhitecture rationaliste en relation avec la peinture et la sulpture`, " Arhotecture Vivante7 : 7. Bouvier Y. and Cousin. C.(2005)`, Ronchamp Chapel of Light`, p.50 Le Corbusier`, The Chapel at Roncamp`, Architectural Press`, London translated by Jacqueline Cullen`, p.99 Lau`, Benson. (2007) The poetics of Sacred Light-an investigation of the luminous environment in the Monastery La Tourette. Plea conference paper no. 0532. Hopkinson`,R.G.`, Peterbridge`,P.`,Longmore`,J.Daylighting`, Heinemann`, London`,1996`,p.11

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The poetics of civic light in Le Corbusier’s Assembly building at Chandigarh. Saurabh BARDE1, Benson LAU1. 1

Department of Architecture and Built Environment, Nottingham University, UK. 

ABSTRACT: The art of expressing architecture through ‘poetics of light’ was mastered by Le Corbusier during his career. Assembly building at Chandigarh, an important Civic Building built by Le Corbusier with emphasis on the creative use of daylight and sunlight has rarely studied in detail. This paper focuses on the critical qualitative and quantitative studies of the luminous environment in the Assembly Building by investigating Le Corbusier’s lighting techniques and the method of transferring his artistic ideologies into reality with light as one of the key architectural elements. Much can be learnt from Le Corbusier’s buildings which mainly use daylight as the primary light source to create the dramatic luminous environments. The research data obtained from this study are useful references for the design professionals to understand the dynamic interaction and sensitive balance between form, space and light in architecture. Keywords: Poetry, architecture, daylight.

1. INTRODUCTION 1.1. Background Chandigarh was a new town developed after Indian independence with the progressive ideologies proposed by the first prime minister of India Mr. Jawaharlal Nehru and Le Corbusier. The State Legislative Assembly at Chandigarh, an important Civic building was designed and built during the same time as Le Corbusier designed the other three religious buildings, Le Tourette, Chapel at Ronchamp and the parish church of saint-pierre, Firminy. The Church at Firminy was completed 41 years after his death by French architect Jose Oubrerie. This paper aims to investigate the luminous environment of Assembly building in Chandigarh and compare its lighting strategies with the Church at Firminy which has similar built form and design ideologies. 1.2. The Indian Context

Figure1. Fatepur Sikri and the Assembly building. FromJencks (2000), Author .

Chandigarh has a seasonal monsoon rains lasting no more than 4 months. The temperatures rise up to 45 degrees Celsius in summers. Le Corbusier’s first visit to India was in the summers of 1950. The idea of the Capitol complex was developed by taking inspiration from an old Mughal town of Fatepur Sikhri in Agra a city near Delhi (Fig1). Le Corbusier was fascinated with the fact that Indians were connected to the cosmic occurrences to such a great deal. He had visited the Jantar Mantar (Fig1) which is a physical solar clock built by precise understanding of the solar geometry and the sun’s movement and it also displays time. Le Corbusier took inspiration from this ‘solar clock’ precedent and developed a design which would respond to the solar trajectory and allow access for the sun rays to enter the building on particular days.

He has also related this phenomena to the Hindu temples in which the deity is illuminated with direct sun rays at particular days of the year. Le Corbusier used symbolism to demarcate the “Indianess” to the building by introducing elements on the roof of this parabola. The horns of a bullock (fig2) and the moon and the sun paths depict the intense relation of Indian tradition to the cosmic beliefs.

Figure2. Le Corbusier’s Sketch book and the Assembly building. From – Phaidon Editors (2008), Author.

1.3. The Legislative Assembly Building, Concept and Ideologies. Le Corbusier designed the assembly at Chandigarh as the centrepiece of the proposed Capitol complex and used architectural elements to display an identity and precise function inside the building. Curtis, states that as at Ronchamp and Le Tourette, Le Corbusier explored the Mythical qualities of light and darkness in the Parliament Building [1]. Light hence can be noted as an important design element in the conception and evolution of the building. The building showed a complete absence of the parabolic form in the initial designs. A box was proposed with the arches on the face to commemorate the central plaza facing the high courts (Fig.3)

Figure3. Le Corbusiers sketches from Foundation Le Corbusier showing the initial façade. (2008).

The composition of the roofline determines the profile of the building with the triangular skylight of the Governor’s chamber, The Parabolic roofline of the Assembly Chamber and the cube containing the Lifts. A metal sky bridge connects this box with the parabolic dome of the Assembly maintaining a

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relation between the forms. (Fig.4) The new design showed the arches been replace by a huge gutter.

Figure4. Section through the assembly chamber. Showing the gutter added. From –Boesiger (1995).

1.4. The Journey to the Assembly Le Corbusier planned the areas around the main assembly chamber and located the forum as the central enclosed space, where the light dramas could be experienced before entering into the main assembly gallery. It is a noticeable space which creates a unique interplay of space and light for each step of the travel towards the grand chamber of assembly. To study the poetics of light in this space, the luminous environment is analysed qualitatively and quantitatively. For the purpose of this study the visitor’s path to the Assembly chamber is demarcated on the plan. The notable drama created by the light is recorded and analysed to understand the impact of the luminous environment on the user. It can be observed that the delegates would normally use two paths to reach the chamber (Fig.5)

techniques used in the assembly building was carried out with the help of tonal sketches. This method was adopted from the study conducted by Lau (2000) for the Monastery of Le Tourette. The technique and the methodology of the typological summarising the light effects are acknowledged to Lau [2]. Physical model test by using heliodon revealed the daylight behaviour on particular days inside the assemble chamber. Computer simulation of the luminous environment inside the assembly was also conducted by using the software Autodesk Ecotect 2009. The available photographs and the drawings of the interiors and the sketches from the previous site visit helped gain extra inputs to the construction of the physical and computer model. The daylight measurement plane was set at 800mm form ground surface. Zones were formed according to the light typologies and were designated according to the function it carries. The zones demarcated is as follows (see Fig.5), Zone 1: The Forum Zone 2: The Assembly Chamber – Hyperboloid Zone 3: The Governor’s Chamber- under the tetrahedron. Zone 4: The Office areas on surrounding the Forum. The daylight studies were carried out by using Radiance, a light simulation programme plug-in for Ecotect which can provide more accurate daylight performance prediction results.

3. LUMINIOUS ENVIRONMENT ASSEMBLY AT CHANDIGARH.

OF

Qualitative analysis of light inside the assembly building The analysis of the light dramas shows that four distinctive types of light have been introduced to the offices and to the forum and finally to the assembly chambers: 1. Balanced light. 2. Discrete light (light beam). 3. Ceremonial light (light beam entering the space at desired times). 4. Reflected light. 3.1. Balanced light.

 

Figure5. Plan showing the journey to the assembly chamber. From– Boesiger (1995), Author.

The first path commonly used by which the delegates enter through the door on the west or from the ramp at the lower levels circulates clockwise to a low height dark passage leading to the chamber. The second path is entered from the same western face of the building but takes an anticlockwise turn towards the ceremonial door. The second path is also joined midway when the delegates use the ceremonial door moving circular, anti clockwise towards the east of the chamber.

2. METHODOLOGY The qualitative analysis was carried out to explore the effects of light inside the spaces of the building. The identification of Le Corbusier’s lighting

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The Forum is a transitional space between the outside and the enclosed auditorium. Evanson, while describing the forum states that lofty, dramatically illuminated, seemingly scaleless in visual dimension, this space is one of the noblest in modern architecture, infusing some of the serenity and exaltation of a cathedral with excitement of a great concourse [3]. It is illuminated by two major light sources: the clerestory windows on the intersection of the wall and roof and the Oculus on the roof slab. It can be said that these light sources inside the forum act as ‘Fill light’ and the ‘Key light’ of illuminations for the whole space rather than an object. (Fig.6) The space under the triple height forest of columns is used for informal gathering of the delegates outside the assembly. The fenestration design suggests a lear intention of avoiding direct sunlight. The sketches captured the cinematic views of the journey and

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

(Fig.8) shows the upper floor flooded with daylight and the ground slab in dark shade.

Figure6. Forum area. From – Phaidon Editors (2008), Sections from author (2009). To dramatise this space, Le Corbusier painted the ceiling black and the floor was finished with polished granite. The floor helps reflect daylight into the interior. The clerestory windows act as the source of fill light to this area while the key light is provided in by the Oculus.

Figure8. Sketch views and Simulated images of the forum. From- Author.

Figure9. Forum area. From – Phaidon Editors (2008), Sections from author (2009).

3.3. Ceremonial light Figure.7 Roof of the two chambers. From– Boesiger (1995), Author. In the Governor’s Chamber which sits inside a square enclosure with a tetrahedron roof opening facing the north. (Fig.7) The north side openings always prevent the direct sunlight. The triangular fenestration has vertical fins similar to the ones used in Le Tourette. They are denser at the eastern side. Thus it can be noted that there is a clear intention to illuminate the chamber with adequate ambient light but no glare which is required for visual comfort in the working environments. The balanced light is uncluttered and emphasises more on creating a mood for calm and undisturbed atmosphere inside the forum. 3.2. Discrete light (light beam). Discrete Light is used in the forum with the puncture in the roof. This “Oculus” is placed at the centre of the forum which acts like a complementary key light source to the clerestory window. (Fig.9) The sudden shaft of light penetrating the otherwise mundane space enlightens ones mood and dramatise the luminous environment. Even though it does not focus in particular towards any object, it brings back the memories of the Hagia Sophia at Istanbul which Le Corbusier had visited in his early days (Corbusier, 1989) [4]. This discrete light illuminates the floor of informal discussion and leads the way towards the assembly chamber. The oculus being at the start of the passage makes area brightly lit.

The Cerimonial light was used as a dynamic design element in the building. The light responds to the sun position and interacts with the users. This light enters the assembly area to commemorate special days. (Fig.7) The ceremonial light was earlier intended to touch the Ashoka pillar at the speakers table; inside the parabolic assembly on 26th January (Indian Republic Day) by mechanically opening the roof itself but later the idea was found to be unrealistic and not feasible. Le Corbusier then designed the roof at an angle to allow beam of light penetrate into the space on the equinoxes and the winter solstice of the year. The roof shows three fixed openings with ornamentation indicating the ideologies of Le Corbusier. They also act as the sun shades to guide the light enter the dome at desired times of the year only. The light drama in the assembly was tested on a heliodon and the results are summarised in figure 11.The heliodon tests show that the building was designed to take in the winter sun and avoid the summer sun as the local climate in Chandigarh is hot and dry. It can be seen on the nd summer solstice (22 June) the sun is exactly above the openings and the roof aperture was profiled in an angle to avoid any direct solar ingress. (Fig.10) The testing of the roof on Equinox shows a beam of light is allowed to enter the dome at noon. There is no direct sun inside the assembly in the morning and afternoon, while the middle and the upper fenestrations help to provide ambient light inside the assembly at other times of the year. On Winter Solstice, a light beam enters the dome and illuminates the walls of the parabola. The surface behind the Speaker’s rostrum glows during this time. The circular form prompted the acoustic to be

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improved inside the assembly leading to the infusion of sound absorbent material along the slope of the dome. The artificial light is used behind the panels to give a uniform light effect and create an undisturbed ambience (Fig.11).

Corbusier experimented the use of these sunshades and use them in other parts in the complex.

Figure.12 Brise –Soleil angles for the offices. From– Boesiger (1995), Author.

4. QUANTITATIVE ANALYSIS LUMINIOUS ENVIRONMENT

OF

THE

 

Figure10. Identification of Dynamic and Static Zones of Illumination inside the parabola.-From Ford (1996), Author.

 

The dome is coloured with bands of red at the bottom and yellow at the centre. The upper half of the dome is left uncoloured and also without any acoustic treatment. Le Corbusier’s design intends to reflect the relation between human and the sun which is expressed by the solar incursion of sunlight beam inside the chamber on particular days.

Fig.13 Isolux contour for the assembly building. From– Boesiger (1995) & Author.

Figure11. The Results of heliodon testing showing the drama of light inside the assembly chamber. From- Author.

 

3.4. Reflected Light The offices located on the periphery of the building are illuminated glazed façade which are shielded by concrete Brise–Soleil’s on the outer sides (Fig.12).The angles of the Brise –Soleil change in accordance to the orientation they face. They are at an angle of 45 degrees on south–west and north– west facades, but are at 90 degrees on the north– east side. They completely avoid the sun entering the office which may cause glare and overheating in summer. The Brise –Soleil help this area receive an indirect illumination desirable for office work. Le

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Zone1: Forum (Fig. 13) The light distribution patterns obtained from the computer simulation were organised with respect to the functions and the light typology. The graph in Figure 13 shows distribution of daylight in the building. The two prominent light sources in forum area show their presence in terms of the daylight intake. It can be noted that the daylight factor is more at the central space of the forum diagonally opposite the west entry. It increases gradually as one moves through transitional path 1 towards the assembly (Fig.5,13). The light intensity varies from 262 Lux to 340 lux because of the Oculus at the roof level. The delegates are directed to move towards the assembly through the passage in which the light intensity is reduced to a miniscule amount before suddenly opening up into the assembly chamber where the light is taken from the skylights above. If one moves from the transitional path 2 as shown in (fig.13) then the circumambulation is from west to east in the anticlockwise direction. The light in the passages have relatively low intensity as one follows the circular path towards the east ceremonial door. The light intensity falls before its gradual increase near the entry to the assembly. The light levels were noted to decrease from 230 Lux to 53 Lux and again increase to 215 lux. The Light intensity again falls to around 119 lux before entering the chamber. The average daylight factor for the forum was calculated to be 4.4% under overcast sky conditions. The uniformity ratio was calculated to be 0.3 which is acceptable for an area intends for informal sitting and not for reading. The balanced light can be observed as the ceiling is dark

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

and the floor is polished. The oculus plays an important role in maintaining the daylight level towards the northern part of the forum which otherwise will be a dull and dark space. Zone2: Inside hyperbola. (Fig. 13) The assembly dome carries three sky lights which allows the diffused light (other than direct solar penetration on key days of the year) to illuminate the sitting arrangement under it. The results show a uniform but a low daylight factor for the area. The assembly is aligned to the cardinal points and the openings at the roof level face south. The two balconies for the viewers which were placed on the concentric southern edge cast shadows on the floor below and do not allow the sunlight from roof to reach the floor at edges. The light distribution pattern indicates that there is a focus of light at the centre of the assembly. The average daylight factor is 0.84 % and the uniformity ratio inside the assembly is 0.5. The Daylight Factor is low inside the Assembly Chamber. The delegate Seats which face the north receives an illumination level of around 250 – 300 lux at the floor level. The central space which is occupied by the officials responsible for conducting the sessions of the assembly is the area receives greater intensity of daylight. The daylight factor was noted to be in the range of 0.2% to 0.4%. The average daylight factor was noted at 0.84% which can be considered to be low. Zone3: Inside the governors chamber - Under the tetrahedron. (Fig. 13) nd The governor’s chamber or the 2 assembly is a cubical chamber where the delegates assemble under the tetrahedron projected skylight. The results show that the area is satisfactorily illuminated all round the day. The square chamber has the roof light located at the height of 4.5M form the floor surface. The Daylight factors fall from the central region to the edge of the cuboid. The central space which holds the seating areas during the assembly is illuminated with greater intensity of daylight. The rows of the seats are designed at a slope as in case of the Assembly Chamber. The tetrahedron is added with Ondulatories, vertical fins which were designed to control the light intake. Considering the overcast sky condition for simulation, results show the Average daylight factor inside the chamber is at 1.93%. An isolux graph of the horizontal illumination levels inside the assembly shows that the lux levels at the edge of the chamber are close to 200 lux. This proves the fact that even though the daylight factor is low the chamber, it has satisfactory illumination received from the tetrahedron. The maximum illuminance levels are 1000lux at the centre of the assembly and falls to 150lux at the edges. Hence the luminous environment can be considered as satisfactory for the function of the space. Zone4: Offices. (Fig. 13) The testing shows that the Brise- Soleil not only prevent the direct sunrays but provide a suitable illumination inside the office work area. The two column rows demarcate the floor space. The light intensity near the windows is presumably high but the light scatters uniformly inside the office. The

Brise-Soleil angles are designed according to the solar altitude and azimuth angle. Considering the external weather conditions of Chandigarh it can be said that the fins (Brise-Soleil) are an appropriate solution for solar control. The illumination levels at the floor are at around 350 to 550 lux, which can be stated to be within the recommended limits. Even though the Daylight factor is seem to drop at the walls, the lowest light level stands at around 100lux. The Office at the South West shows an Average Daylight Factor of 4.8% which can be considered as a well day lit space. The Office at the North West shows an Average Daylight Factor of 2.5% which indicates that supplementary artificial light is required at times. The uniformity ratio was calculated to be 0.5 which shows that the office area is uniformly lit. The Office on the North East receives insufficient daylight as it falls on the northern side and never receives direct sunlight on the façade. The Brise – soleil angle was intentionally kept at 90 degrees but this does not benefit much for the daylight ingress, but the on the contrary obstruct the light. The average Daylight Factor was calculated at 1.2% which implies that artificial lighting is required for most of the time. Daylight factor%

Assembly chamber Forum Offices SW Offices NW Offices NE Governor’s chamber

Uniformity Ratio

Max

Min.

Avg.

1.4

0.07

0.9

0.06

14.4 8.8 3.7 5.2 4.1

2 1.4 1.5 0.1 0.8

4.4 4.8 2.5 1.2 2.06

0.4 0.3 0.5 0.1 0.3

The table indicates the values recorded and shows its close proximity towards the actual required.

5.

COMPARATIVE STUDY BETWEEN ASSEMBLY AT CHANDIGARH AND CHURCH AT FIRMINY –FRANCE.

For the better understanding of the daylighting design strategies used in the Assembly, a comparative study was carried out between the Assembly and the Church at Firmny, France. The Church was completed in the absence of Le Corbusier and the building interior is mainly artificially lit which may not be Le Corbusier’s original design intent. The results of the daylight analysis were categorised into different times of the selected days to understand the exact behaviour of the two light sources on the roof, the east and west windows and the peripheral openings. Morning Light: The “Orion” effect is seen to work when the sun is on East. The small star like apertures on the surface of the wall help achieve the effect. The alter shines on till 11 am in mornings and becomes dark after noon time. This effect seems to fade much earlier in winters and on equinox. Mid day Light: The two cannons start to emit light at noon time, lasting until 3pm. The focus is targeted towards the cone and gives a diffused lighting effect at the floor level. The design of these two cannons is similar to the skylights at the assembly, but they are insufficiently sized to illuminate the church interior. Evening Light: The west Window plays an important role of keeping the focus on the altar. This focus

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gains importance on Christmas, Easter and St. Peter’s day. This light is similar to the ceremonial light in Assembly at Chandigarh.

Figure 14. Comparison of daylighting strategies.

Daylight factors from Artificial sky testing showed that the light levels in the Church at Firminy are too low for the visitors to rely on natural light. The lux levels drop from 15 to almost 8 lux at certain places compared to 1300 lux or more outside. The Daylight Factor is hence below 0.01% and the Uniformity Ratio is 0.06% which shows low luminosity and uneven light distribution. The low illuminance level inside the church makes the use of artificial light necessary during the day. The windows with the slope pointing downwards do not benefit the luminous environment of the church. The windows have same sun shading device on all the sides which does not allow the light penetrating into the interior. The Church at Firminy even though has similar daylighting strategies as the Assembly, its aperture sizing and design does not provide adequate daylight to the interior of the church. Le Corbusier’s improvisations as seen in the assembly building where he sculpted the roof of the building in order to allow selective solar ingress is seen absent in Church at Firminy.

6. CONCLUSION The success of the design of the luminous environment inside the assembly lies in the visual delight that has been achieved. The use of light as a element to illuminate the space in order to create various impacts on the users is evident from the study of the fenestrations and its designs. The light dramas created by the collective impacts from the balanced light, discrete light ceremonial light and the reflected light inside the assembly further enhance the visual environment. Le Corbusier designed the roof as a solar clock to allow the light to enter the area at particular dates and times and illuminate the speaker’s area. This interaction between the occupants and the sun movements was sourced from traditional Indian architecture in which the deity is highlighted with sunlight beam on certain days inside the temple. These lighting technique used heightens the poetics of light in the Assembly.

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Although some areas tend to get dark during the day, it can be concluded that the emphasis on keeping the area cool from the scorching heat and using artificial light as a supplementary light due to the function was the priority. By comparing the luminous environments of Assembly and the Church at Firminy, unlike Ronchamp or Monastery of Le Tourette, the Church at Firminy does not evoke the poetic sensation. The lack of adequate daylight illuminance inside the church does not allow the luminous environment to be well daylit. Since the interior of the church is mainly artificially lit, the church looses the Le Corbusierian identity. By comparing these two buildings, it is evident that the drama created by natural light cannot be recreated by artificial light. Learning from Le Corbusier, It is important for design professionals to understand the solar geometry, trajectory and the effects of light on architectural forms and to use natural light as form giver in architecture.

7. REFERENCES [1] Curtis, W. (1986). Le Corbusier: ideas and forms. Oxford: Phaidon Press Limited. [2] Lau, B. (2000). Luminious environment at Le Tourette. M. Phil. Dissertation. University of Cambridge: School of Architecture Cambridge. [3] Evanson, N. (1966). Chandigarh. London: Cambridge, University Press. [4] Corbusier, L. (1989). Journey to the East. London: The MIT Press, Cambridge, Massachusetts. [5] Phaidon Editors. (2008). Le Corbusier Le Grand. London: Phaidon Press Limited. [6] Jencks, C. (2000). Le Corbusier and the Continual Revolution. New York: The Monacelli Press, Inc., and Charles Jencks. [7] Boesiger, W. (1995). Le Corbusier et son atelier rue de Sevres 35. Bale Switzerland: Birkhauser. [8] Ford, E. (1996). The Details of Modern Architecture, Volume 2, 1928 -1988. London: The MIT Press, Cambridge Massachusetts.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBNth xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Architectural light in Contemporary Religious buildings Isha Anand Architectural Association School of Architecture, London, UK ABSTRACT: Daylight can be very informative in the generation of architectural form and has been a celebrated tool in highlighting cultural, contextual and experiential regard in architectural design. Exploring this concept, the paper assesses and re-interprets spatial, sensorial and form-giving characteristics of daylight using religious buildings as a forum. The project explores the effects created through daylight in three iconic religious buildings; Notre Dame du Haut, the Church of Light and the Bagsvaerd Kirke; the daylighting effects created in these buildings are identified, evaluated and analysed. The three built precedents had very unique intentions with the kind of daylighting ambience created, they were evaluated in the same way; daylight factor used for analysing the distribution of light in the buildings, solar penetration to study the role and extent of solar play in them and luminance distribution to the study contrast and glare issues. The study helps elaborate the process and intent of the architects to create a certain theme in the building through daylighting and the tools that go into creating it. Keywords: daylight, religious building, daylight distribution, illuminance

1. INTRODUCTION

2. RESEARCH QUESTIONS

This visual understanding of the art of building is manifested in Le Corbusier’s poetic credo: “Architecture is the masterly, correct and magnificent play of masses brought together in light.” [1] Daylight indeed is an important part of the revelation of architecture and the role of daylight in architecture is dissected and integrated at the time as an art and science, an emotion or quantity [2]. This does lead to a loss of holistic approach understanding to the role of daylight but does provide tools to scrutinize some architectural marvels and be able to acquire share the vision of the creators. However, there is a need for both personal emotional needs- of well being comfort and health- and the performance for an environmentally sustainable future. An integral move towards this approach has been observed in religious buildings. Daylight is elevated from the mere tool for visibility to evoking emotion and creating symbolic gestures. For over centuries religious buildings have developed their own liturgy and architecture, and light features prominently in the symbolism of most religions, it is embraced, shadowed, reflected, concealed or revealed to determine the ethereal quality of space. [3] With most buildings possessing a slice of sun which belongs to the place. For example the mosque in the desert dissolves light, the Nordic churches explore the darkness of light and the classical temple with its plastic forms reveals the dialectic of light [3] . Religious buildings provide ample opportunity to study the role of as both a functional and experiential element in architecture.

The main research questions are, what factors influence the effect of light in marking/making a certain outcome or event and how are the effects rationalized objectively through concrete elements such as the use of material, source and geometry of space? Religious buildings can prove to be a possible forum for this study as the intention of daylighting scheme in the built environment has greater purpose than mere visibility. The answer to these should be able enumerate a process for developing evocative architecture through daylight.

3. METHODOLOGY The methodology for this paper is based on a twofold approach: 3.1. Criteria for selection of built precedents The first step is to determine the most recurring effects tried to be created in religious buildings and identify certain built precedents utilizing them. This step shall be enumerated through deconstruction of daylight effects in valid built precedents. The precedents chosen for the study have been based on three distinct themes, a response for creating a stimulating environmental experience, a response to the cultural sensitivities of the place and people and a response to the systems of the place [4]. Subsequently these are Notre Dame Du haut at Ronchamp, France, Church of Light at Osaka, Japan and the Bagsvaerd Church at Copenhagen, Denmark All three precedents successfully use daylighting as a major tool to express these themes. This chapter tries to decipher the thoughts behind the creation of these buildings through valid site and analytical work.

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

3.2. Analysis This has done through effective literature review and analytical work. The process is very objective and consists of deconstructing the effects of light to the source of light in the building, and components of the building like geometry and materials. This step also includes finding valid performance indicators for the same. The buildings have been analyzed through: daylight factor for analyzing the distribution of light in the buildings, solar penetration to study the role and extent of solar play in them and luminance distribution to the study contrast and glare issues.

4. NOTRE DAME DU HAUT, RONCHAMP 4.1. Introduction A cinematic vessel [3], the Chapel at Ronchamp is a timeless piece of architecture. The interior of the church is an in the expressive use of light which translates into a dynamic form commanding the summit of a hill at Ronchamp. Architecturally, Ronchamp is system of convex and concave concrete walls covered by a shell. The altar is on the east wall which has small apertures in it. Light is entered into the space by shafts of light in southwest corner, orthogonal openings in the northeast, light shafts in the northern wall( which mark the entrance to the chapel) and the south wall which is punctuated with deep splayed windows of variable sizes proportions and fitted with coloured glass in some. [5]

                       

Fig.4.2 Solar movement in the narthex of the chapel, September 21 (Ecotect [7])

                       

4.3. Daylight distribution

4.2. Solar play The chapel acts as a forum for capturing pieces of sun at various times of the day. Each daylightcapturing device is timed and placed according to solar events/ angles [6]. At dawn east wall comes alive, in late morning the vertical fissure dissolves away under the impact of sun, followed by an afternoon long illumination of openings in the south wall. The embrasures capture different moments of the sun. Cavities brighten and dim at different hours and remain lit for different extents of time. The embrasures also have a seasonal rhythm, their openings adjusted in section to intercept high summer sun, while letting low angles of winter sun penetrate through the width of the church. Figure 4.2

2

                         

Fig. 4.3 Solar movement in the west tower of Chapel at Ronchamp, September 21 (Ecotect [7])

Fig. 4.1 Notre Dame du Haut, Chapel at Ronchamp

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shows the solar penetration through the south wall in the narthex of the church on September 21 [7]. The two back to back chapels receive sunlight for half a day a piece; the west tower has been shown in fig.4.3.

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In terms of distribution in the central nave has a very uneven distribution of light with bright and dark zones. The brightest zones in ascending order are the orthogonal windows in the north east corner, the entrances at north and south east, the west facing light scoop, area adjoining the south wall and the brightest zone is the area under the north facing light scoop. The darkest zone is the east facing light tower. Although the tower is equipped with the same apparatus as the other two light scoops, the interior of it is painted red. The resultant reflectance is approximately ¼ of the other surfaces , thus the wall reflects little light down the tower. The results have been interpreted from the analysis of the chapel in Radiance [8]. The results have been expressed in fig.4.4.

 

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

                                           

5. CHURCH OF LIGHT, OSAKA 5.1. Introduction Connected with the link between light and spirit of a place is the link between light and culture. [9] Japan is one country which shows a traditional sensitivity towards natural cycles of time, and the temporality is expressed in a variety of ways in its culture and religion Elements such as shoji screens are used to alter the interior environment throughout the day as the sun moves across the sky. The effect of light on these screens is purely captivating [10] This event of light and shadows is also an outcome of how the Japanese have also embraced it’s rather dull sky conditions by affectionately naming it Rikyu Grey. [10] The omnipresent monochromes sky conditions are replicated to create very subdued and passive environments. The temporal phenomenon commonly expressed in the country’s traditional buildings continues to be of relevance to Architect Tadao Ando’s works. Ando describes that Architecture is intimately involved with time [11] and this is clearly visible in most of his works such as the Church of light. 5.2. Solar play

Fig. 4.4 Daylight distribution in the main body and down the light towers at Chapel at Ronchamp (Radiance [8])

4.4. Luminance ratio The main zone of the chapel is characterized by even texture and colour of material. Hence the luminance’s are distributed quite smoothly with the exception of the east end of the chapel which sharp contrast as indicated in. This leads to a very animated effect as the visitor is facing the altar. If we look the other way round the luminance distribution is more subtle and smooth as the light sources are indirect (The light scoops). Seasonal study also shows punctuation of the main narthex with areas of high luminance greater intensity in summers[8]. The luminance studies have been demonstrated for the main altar and south wall for June 21 in fig 4.5 showing smooth luminanaces with areas of high brightness

    9:00 a.m         12:00 p.m        

cd/sq.m

3:00 p.m

   

Fig. 4.5 Luminance study for the altar and south wall of chapel at Ronchamp on Jun 21 (Radiance [8])

The orientation of the chapel and the presence of angled wall limit solar penetration only from the crucifix opening. (With the exception of solar penetration from the North West in late evening in summers). The sun patches caused by the crucifix do not cause any potential glare problems due to the architectural proportions of the opening, the slenderness of the proportions along with the depth of the opening (250mm) limit the area of solar penetration to a tolerable extent. Solar studies in ECOTECT [7] reveal that the sun patches are limited to the altar area for most part of the year, only accessing into the deeper zones in winters. The experience of time and direction is very pronounced and the combination of this simple daylighting strategy with architecture creates a very vivid experience for the visitor. The process has been enumerated through visuals in fig 5.1 for September.

                       

Fig. 5.1 Solar study for Church of Light September 21 (Ecotect [7])

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PLEA2011 - 27th International conference e on Passive an nd Low Energy Architecture, A Lo ouvain-la-Neuve e, Belgium, 13-1 15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Daylig ght factors we ere simulated for f the Church h of light usin ng Radiance [9] for overca ast conditionss in Decembe er. The distrib bution of light in the Church h of light can be considere ed to be fairly even with the exception n of a few brig ght zones. Th he brightest zo one of the church is the entrance area; this area a is however cordoned off from the ma ain chapel by the w This enab bles to reduce e potential gla are. angled wall. The main n chapel has very low dayylight factors, an average of o 1.24%(fig.5.2). More than n 90% of the floor f area has a daylight facctor of 0.5% with w a small zo one ening brightlyy lit. Across the near the crucifix ope oo the dayligh ht factors are fairly f low with the section to exception n, the ends of o the cross do d lead to so ome bright spo ots on the no orth-east and south west wall, w but the patches are distributed smo oothly because e of o the concre ete surface. The T the high reflectance of a the centre c (throug gh the opening) section across shows so ome bright patches p at bo oth ends of the chapel, these t howeve er have veryy limited area a of impact. Again A the facctor of archite ectural proporrtion comes intto play, the arrea with high daylight d factorrs is small, the e therefore the e visual impacct of the chang ging daylight level is felt bu ut is not overrwhelming to the extent of causing glare.

 

                                     

9:00 a.m

12::00 p.m

3:00 p.m

6. BAGSVAE ERD KIRKE 6.1 1. Introductio on

5.4. Lum minance ratio o Lumin nance levels were w simulate ed for Sunny sky conditionss in June acro oss the day [8 8]. This was done to evalua ate any exceed dingly high lum minance ratios in the field of o vision. The simulations show s a maxim mum luminance e ratio of 1:2 20, which is within w accepta able range [12 2] On evaluating the luminan nce distribution ut the day accross the chap pel on Jun 21 as throughou expressed in fig.5.3 (un nder sunny co onditions) it wo ould e that the luminance ra atios be important to note between the zone of the t altar and the seating area a

4

  1200 1  1000 1   800   600 400   200   0                               1400 1

Fig F 5.3 Luminan nce across the ssection of Churc ch of light (Ra adiance [8]) and d subsequent ra ange in adaptatiion level [2]

Fig 5.2 Daylight factor distribution acro oss the plan and d s section of Churc rch of light (Radiiance [8])

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aintain to 1:10 0 or higher w which is fundamental for ma cre eating areas of visual ffocus. The size and pro oportions of th he opening altthough a huge e symbolic ges sture are key to creating this effect.

Luminanace cd/sq.m

5.3. Day ylight distribu ution

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With relationship to place, each place has its own ligh ht and the spirit s of a p place, Genius s loci [9] exp perienced as a specific kiind of light and a mood, res sulting from th he local climatte and a certa ain slant of sun n, phenomena a recognized immediately in n any true pla ace. A group of architects w who have a heightened h sen nsitivity to this process are e the Nordic architects [6]. They have found a proccess of inventting highly ima aginative light scoops and d skylights, with w highly refflective finishe es to capture e precious liight. in a clim mate where daylight is scarce. A brilliant example in this league e of contexttual response e is the Bagsvaerd churcch in Copenha agen, Denmarrk. The church has been dessign by Jorn Utzon U and wh hat started as an obsession to abstract the skies wa as rendered as a a remarka able laboratory y of light. Utz zon interplayss all three of tthis day lightin ng themes in the Bagsvaerrd Church which are· Unde erstanding tha at reflected or diffused light is usually pre eferable to a directed view of a light source, e design should be sensitive e to the sun’s s daily and the ann nual paths witth reference tto particular places p and the e realization that light rece eiving devices s could be ma ade into inhabitable spaces [13]

PLEA2011 - 27th International conference e on Passive an nd Low Energy Architecture, A Lo ouvain-la-Neuve e, Belgium, 13-1 15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

6.2. Sola ar play The design d for the e Bagsvaerd church is hig ghly sensitive to the solar cycle c of Copenhagen. The low altitude sun can alwayys be a source e of glare as it is always around the corner of the eye. e The unussual design fo or the church h takes care of this problem. Solar studies in ECOT TECT [7] reve eal that the so olar penetratio on in the churrch is only allo owed after no oon. The exten nt of solar infiltration is limitted to the brim m of the light scoop much h above the visual field. The T i is in n June as dem monstrated in fig. deepest infiltration 6.1 with high h solar altittude and the shallowest be eing in winter. This tempora al phenomena a is also limited d to a period when the litturgical activities are finished hence the e visitors can n enjoy the ch hurch with vissual animation n.

                 

Fig. 6.1 1 Solar moveme ent in Bagsvaerd d church, Jun 21 (EC COTECT [7]).

6.3. Day ylight distribu ution Daylig ght factors we ere calculated d for the chu urch under Overcast sky conditions in n the month of Decembe er [8]. The luminous environment of Bagsvaerrd church is defined by a very unifo orm distributio on of light. Th he average daylight d factor for the room m is 1.64% with w the maiin visiting arreas illuminate ed evenly. The e darkest zone is the entrance zone from m the west wh hich lies in the e leeward area a of the light scoop, butt ambient lig ghting from the epancy in daylight adjoining corridors makkes the discre levels verry small.

On evaluatin ng the distribution of light th hrough the sec ction of the ch hurch (fig.10) there is a dis screpancy in the upper ha alf and the low wer half of th he church. This however co oincides with tthe fact that th he brighter zon ne although contributes c to the overall illumination (reflection of the e surface of the light scoop)) but is not ectly visible to o the visitor. dire

 

6.4 4. Luminance e ratio The luminance distribution n in the main sanctuary has s very low disstinction, as shown in fig.11 1 over the cou urse of the da ay in a summ mer day. The luminance vallues howeverr are enhancced considera ably when the ere is solar in nfiltration as o on Jun 21 att 4:00p.m. This leads to a fair f conclusion n that the sanc ctuary has fairrly uniform brightness b ratiios with the exception wh hen there is su un movement iinside it.

                                                         

Fig g. 6.3 Luminancce study in Bagssvaerd church on Jun 21 at 9:00 a.m, 12 noon and 4:00p.m (Radiance e [8])

7. CONCLUS SIONS

Fig. 6.2 Da aylight distributio on in Bagsvaerd d church (Radia ance [8])

The three built precede ents had verry unique inte entions with the kind of daylighting ambience cre eated, they were w evaluate ed in the sa ame way; day ylight factor for analyzing the distributio on of light in the t buildings, solar penetrration to stud dy the role and d extent of solar s play in them and lu uminance dis stribution to the study con ntrast and gla are issues; in order to iden ntify certain th hemes in the e buildings

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PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

through daylighting and the tools that go into creating them. The following observations were made: 1. Notre Dame du Haut: the daylight ambience of the chapel is governed by solar movement around it. The apparent brightness of areas is orchestrated by solar inclusion or exclusion and is purely time and season based. 2. Church of light: the main body of the church almost has a gravitational pull towards the cross opening, this being driven by daylighting principles. The proportions of the opening are small as compared to the wall area and created a great brightness contrast between the opening and the immediate wall surface. If we look across the section the brightness of the area near the cross opening is elevated substantially from the remaining body of the church. Solar movement has a great role in indicating the passage of time but is secondary to the visual focus created in the chapel. 3. Bagsvaerd Kirke: the church has predominantly uniform daylighting conditions with primary daylighting source oriented towards west. This results in permitting only diffused light into the sanctuary for most part of the day. The proportion of the light funnel does not allow any solar infiltration in the occupied zone. The average daylight factors of the three buildings are relatively low (< 2%, with 2% being the norm for a space to appear day lit [12]) but they are gratified by instances or areas of high brightness to create an overall stimulating daylight environment. It is worth noticing that the utilization of some very basic tools has led to the creation of exemplar effects in these iconic buildings. While the chapel Copenhagen adopts a form generative response to daylighting effects, the chapel at Ronchamp uses both form generative ( in the form of the light towers) and locating and proportioning the fenestrations appropriately and the Church at Osaka does so through the manipulation of fenestration in a simple concrete box. This leads to a reasonable conclusion that the architectural form or its appropriate punctuation can be devised with an underlying theme or intent besides illumination, light can be embraced, shadowed, reflected, concealed or revealed to highlight areas of a space, set a mood for an event or evoke a certain emotion

8. ACKNOWLEDGEMENT I would like to thank my tutor Dr.Joana Carlos Goncalves Soares for her vital encouragement, knowledge, my family and my dear friend Nitin for their support.

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9. REFERENCES [1] [2] [3] [4]

[5]

[6] [7] [8] [9] [10]

[11] [12]

[13]

J. Pallasma , Tangible light: integration of sense and architecture, Daylight and architecture, magazine by Velux (Issue 07), 2008 N Baker, K. Steemers , Daylight Design of Buildings, James and James, 2000, p-5, 172 H.Plummer , Poetics of Light, A&U Publishing Co. Ltd, 1987, p5, 157,158 M.DeKay, M Guzowski, A Model for Integral Sustainable Design Explored through Daylighting, Proceedings of the American Solar Energy Society, 2006 B Lou , The Poetics of Sacred Light - a comparative study of the luminous environment in the Ronchamp Chapel and the Church in the Monastery of La Tourrette, PLEA 2008 – 25th Conference on Passive and Low Energy Architecture, Dublin, 2008 H.Plummer, Masters Of Light, First Volume: Twentieth-Century Pioneers. Tokyo: A&U, 2003 Autodesk Ecotect 2010 Desktop Radiance 2.0 Beta M Millet, Light Revealing Architecture Van Nostrand Reinhold, 1996, p-9, 10,11 A Veal , Time in Japanese architecture: tradition and Tadao Ando, Architectural Research Quarterly, 6:4: Cambridge University Press, 2002, p-349-362 Drew P ,Church on the water and Church of the light: Architecture in detail, Phaidon publishing, 1996, p-19 M Claude Dubois , Integration of daylight quality in the design studio: from research to practice, PLEA2006 - The 23rd Conference on Passive and Low Energy Architecture, Geneva, Switzerland, 6-8 September 2006, 2006 R Weston, Jorn Utzon Logbook Volume 2: Bagsvaerd Church, Edition Blondal, 2005

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

The user intervention on the environmental delight of the BASF research house at university of Nottingham DINESHKUMAR SEKAR1, BENSON LAU2, JYOTHSNA DURGA GIRIDHAR3 1

Department of Architecture and built environment, University of Nottingham, Nottingham, UK Department of Architecture and built environment, University of Nottingham, Nottingham, UK 3 Department of Architecture and built environment, University of Nottingham, Nottingham, UK 2

ABSTRACT: This paper investigates the influence of the occupants’ active control on the ventilation and thermal performance of the BASF Research house built at the University of Nottingham. The objective of this research project undertaken by the School of Architecture and Built Environment, Nottingham University is to explore the feasibility of building low cost and environmentally friendly houses. The research outcomes have demonstrated that it is feasible and possible to build affordable low energy houses in the global context of normally over-priced and energy inefficient domestic dwellings. Also detailed post occupancy evaluation has been conducted to realistically monitor the building’s environmental performance. After completion, the BASF House is occupied by a group PhD and Masters research students, who have been living in the house and monitoring the performance of the house. The objective of this paper is to explore how the daily operation of the home by its occupants after construction determines the environmental comfort and occupant satisfaction. The research involves the investigation of the current usage pattern of the ventilators by the occupants and the house’s comfort conditions due to this usage pattern. Qualitative analysis is done by means of on-site observation, interview with occupants and user feedback from the survey by using questionnaire. Quantitatively, the building’s performance has been assessed starting from the understanding of the site context, the impacts from the macro and micro climate. The research data obtained from this research raises the awareness among the building professionals and users as how the proper user intervention would potentially enrich and enhance the environmental delight in architecture. Keywords: sustainable house, passive environmental control, user intervention, environmental delight.

1. INTRODUCTION Building usage pattern by occupants have a significant impact on the overall performance of a building. Perception of thermal and visual delight varies among different individuals. The collective usage patterns by different occupants have significant impact on the efficiency of a building. This study focuses on the effect this pattern on a high performing building like the BASF House. After understanding the design and environmental design principles based on which the BASF house was constructed, this research explores the real performance of the building, which was designed and built based on those theories.

Figure 1 Dry bulb temperature, Nottingham - (Source: CIBSE DSY weather data)

2. BASF HOUSE The BASF House is one of the University of Nottingham’s Creative Energy Homes Projects, where 6 houses of varying strategies and efficiency were constructed in the University campus. The University is considering futuristic designs for a sustainable tomorrow. This house has been designed to demonstrate that it is possible to build an affordable low energy house and it was designed by Architect Dereck Trowell.[3] It was officially opened on January 30th 2008. Currently the house is occupied by 3 research students belonging to different age groups, and cultural backgrounds.

Figure 2 Relative humidity, Nottingham – (Source: CIBSE DSY weather data)

2.1. Climate Nottingham (53°0´N 1°2´W) is geographically located in Central England. The weather data used is CIBSE DSY (Design Summer Sky - Year) weather file which was developed taking all the warmer years into consideration considering the general change of weather towards warmer conditions. The range of

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

temperature in summer (June to August) is between 14.86°C to 29.5°C, while in winters (December to February) is from -6.7°C to 3.3°C which is well below comfort range. The comfort boundaries during summer can be delimited at the upper end by a maximum of 70% relative humidity and a temperature of 25° C. The average summer conditions in Nottingham just fall within these limits both in terms of temperature and RH. The winter period in Nottingham is humid with temperatures ranging from -5° C to 10° C. The comfort in winter time is defined as 20° C in terms of temperature and ranges between 60% & 80% RH. This shows the need for capturing heat during winter. Nottingham has prevailing winds predominantly from Southwest that has an overall effect of reducing the temperature and increasing the humidity characterizing the cold winters.

dining room areas which helps in stack ventilation. All other energy related controls like solar thermal hot water cylinder and rainwater harvesting controls are located in the ground floor. Window less facades on the north and east enables future terracing. The Northern facade has smaller windows enabling daylight while controlling heat loss from this facade. The house employs insulated concrete formwork (ICF) (U Value: 0.177 W/m2°C) for its foundation, Structurally Insulated Panels (SIPS) (U–Value: 0.15 W/m2°C) for its first floor walls and roof, and Phase change materials incorporated in plasterboards in the internal partitions to regulate temperature. Since it is a display/research project the house is open to visitors two open days per month.

Figure 5 Photograph of BASF house (Source: Author) Figure 3 building plans (Source: Author)

3. EFFECTS OF CLIMATE ON PASSIVE DESIGN 3.1. Effect of solar radiation

Figure 4 Photographs showing building elevations Northleft, South-right (Source: Author)

2.2. Building information The design brief was to build a highly energy efficient house which at the same time is affordable. The result is a compact house with an open floor area which relies heavily on passive solar principles. The house has dense vegetation in the North, East and West which acts as a noise buffer. Southern side of the house is a natural mound sloping downwards allowing good solar exposure. The house has buffer spaces in the North that contains the entrance lobby, biomass boiler and bike storage. It has a conservatory in the south which benefits the living areas in the Ground Floor and the bedrooms in First floor adjoining it. The conservatory has external shading devices designed to protect the southern facade from direct solar radiation during summer to prevent overheating. It has a centrally located stairwell separating the living room from the

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It is clear from the solar study that the building would benefit from the useful solar gains in winter. The building captures the solar radiations from the 100% glazed south surface and it acts as the area which absorbs the Sunlight and the. The external shading devices have been designed to protect the southern facade from direct solar radiation during summer to prevent overheating, which is evidently seen in the solar study. 3.2. The role of building envelope The building envelope acts as a climate moderator. It provides a balance between the heat gain and the heat losses required to maintain a comfortable interior. The house is designed such that the floor area is compact .The north; west and east facades cut off the cold with the use of heavy insulation and limited openings to admit in adequate daylight. The materials used for the building envelope are explained in detail below. Insulated Concrete Forms (ICF) is a lightweight means of constructing walls that is incorporated in the ground floor of BASF house. It gives form to the ground floor of the building and it has high insulating properties. Low energy Concrete is poured in between to fill in the space. The concrete is made water resistant by the use of Relius. Prefabricated Structural Insulated

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Panels (SIP) is used in the First floor walls and the roof. These are made of Elastopor H Polyurethane foam insulation (low thermal conductivity) sandwiched between OSB (oriented strand board) [1]. Heat absorbing pigment present in the paint coating used for steel has the capacity to transfer the heat to the material and into the air. Smart Board plasterboard has been used on the internal wall facades. This helps to regulate temperatures, because it contains Micronal PCM phase-change material - microscopically small plastic spheres with a wax core. When the temperature rises, the wax melts and the phase-change material absorbs heat. When the temperature drops, the wax solidifies, and heat is emitted [4].

Figure 6 Section with environmental strategies-summer (Source: Author)

During summer the buffer zone ventilators are open to prevent excessive heating and are also included as a living space. Convective cooling in the night by automatic ventilation controls keeps the indoor temperature under control [6]. The centralised location of the staircase ensures movement of air by stack effect to the first floor. The warm air is extracted by windows places along the ridge line on the roof. 3.4. Previous works on the house’s thermal performance The pre construction report on the thermal performance analysis of the BASF house done in the University of Nottingham by Lucelia Taranto Rodrigues, PhD candidate, Lecturer in Architecture and Dr. Rosa Schiano-Phan explains the progress on the dynamic simulation of the thermal performance of the BASF house. Based on the conclusions from the report the material specification of the external walls, internal walls and the glazing was revised to improve the performance of the house. The report also discusses the difference in the performance of the building with original specification and proposed UK passivHaus specification for construction. This report remained as a strong base for understanding the thermal performance building better. 3.5. Building usage and people’s perception The building has been occupied by Nina Hormazábal Poblete and Deborah Adkins, two PhD students at the University of Nottingham. Nina, stays along with her husband in the home and uses the bedroom on the south west. Deborah, is in her third year PhD in the university and uses the bed room on the south east. They have been living in the house, and monitoring the performance of the home as well. It is interesting to understand how the rooms are used by users from different generations, culture. This report will discuss the influence of the occupants’ on the internal temperatures according to their usage pattern in the two bedrooms. 3.6. Onsite Observations th

Figure 7 Section with environmental strategies-winter (Source: Author)

3.3. Environmental comfort

strategies

for

thermal

The buffer zone in the Southern facade although acts as the area which absorbs the Sunlight and the heat so that they may be redistributed within the building. During winter the Openings between the Southern part and the rest of the house can be opened to allow recirculation of warm air, see figure 7. The Ground to air heating system allows the preheated warm air to be brought into this area and helps in transferring heat from the earth into the building. The facade in the southern part is fully glazed (Interior double glazed curtain wall, U-value of 1.6W/m2K and exterior double glazed curtain wall, U-value 2.7 W/m2k) with multi layered sun spaces.[5]

Visiting the home frequently between 26 March th 2009 and 7 April 2009 the following observations were made. This time period falls in the spring period. The occupant’s usage pattern derived from the study has been considered as the spring usage pattern. The outdoor dry bulb temperature was less than 16° C on an average during midday, and it was for rainy couple of days. No artificial lights were used in the home during the day. The house takes full advantage of its glazed south facade, both in terms of daylight and solar gains. Irrespective of the outdoor weather conditions, the indoor temperatures in the living and dining area were warm and comfortable, showed temperatures ranging from 22°C to 24°C. All the ventilators in the living/dining space were closed during most of the time in the day. The solar area showed temperatures above 27°C during midday, as expected. It was taking advantage of the direct solar gains. The kitchen was

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warmer than the living/dining area, probably because of the heat gain from the appliances. The buffer space in the north helps in maintaining the internal temperature and prevents the cold wind entering the habitable space. The bedrooms in the first floor were warm and comfortable and showed temperatures ranging from 22°C to 24°C during midday. The shading device in the south was protecting half of the glazed facade from mid day sun, as seen in the solar study. Overall, indoor conditions were warm and comfortable. There is a risk that house might get overheated during the summer days, a detailed site observation during summer would help to answer questions related to overheating during summer.

survey period (31st March – 6th April). The usage pattern of the openings was derived from this exercise. The ventilators marked (in yellow) show the ventilators that were manually opened by the occupants. The feedback from the survey was used to arrive at a simple usage pattern of the ventilators and doors. This pattern can be regarded as the spring usage pattern of the doors and ventilators of the UK BASF research house. [7] Also this pattern enables to identify the influence users on ventilation and the internal temperature. Comparing the onsite temperature measurements on the survey dates, enables to identify the influence of the users on the ventilation and thermal performance.

4. RESEARCH METHOD The study was carried out in 2 stages. The first stage focuses on the usage pattern of the regularly controlled openings in the House. An extensive list of all the ventilators and doors in the building was made and a survey was conducted to understand the usage pattern of the doors and ventilators. A questionnaire containing the hour schedule was stuck in all the doors and ventilators that were used.

Figure 9 Schedule of doors, with the ventilators that were used in survey period marked. (Source: Author) Windows/ Ventilators

Thermal zone Usage time

First floor sunspace exterior (south west)

Zone 1

8:00 - 17:00 hrs once a day

Top ventilator bedroom 3 (stack)

Zone 10

8:00 - 17:00 once a week

Top ventilator bedroom 3 (stack)

Zone 10

8:00 - 17:00 once a week

Bathroom ventilator 1

Zone 11

7.30 - 14.30 - all occupied days

Bathroom ventilator 2

Zone 11

7.30 - 14.30 - all occupied days

First floor stair case

Zone 3

5 hours a week

Kitchen ventilators

Zone 6

13.00 -13.30 occupied days

First floor south west bedroom interior

Zone 10

8:00 - 17:00 once a day

Doors

Thermal zone Usage time

Exterior South Ground floor - Door 2

Zone 1

18:00 - 19:00 hrs once a day

Interior South Ground floor - Door 4

Zone 2

18:00 - 19:00 hrs once a day

Interior South west bedroom - Door 5

Zone 10

14:00 - 16:00 hrs, twice a week

Interior South East bedroom - Door 6

Zone 8

14:00 - 16:00 hrs, twice a week

Figure 10 spring usage pattern of ventilators, derived from occupant usage. (Source: Author)

Figure 8 Schedule of ventilators, with the ventilators that were used during survey period marked. (Source: Author)

4.1. Occupancy The House is occupied by 3 occupants, 2 of whom are PhD students in the School of the Built Environment, University of Nottingham. The performance of the house is monitored by Webrick system in terms of its thermal performance, daylight performance and energy consumption. Related details such as increase in number of occupants when the house is open to visit, duration when hot water and other systems are used are recorded by the occupants for each day. The study of the occupants’ usage focussing on their thermal comfort was carried out from 26th March to 7th April 2009. 4.2. Occupant involvement in research The occupants were asked to mark the time they open/close the ventilators/doors and the reason for opening (i.e. ventilation, smell, and special usage). Based on the survey, it was possible to identify the ventilators and doors that were used during the

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Qualitative analysis through interviews was conducted to measure the occupants overall satisfaction with the House. The second stage of the study involves analysis the thermal performance of th th the house from 26 March to 7 April 2009 by quantitatively analysing the data collected by the wetbrick system. The qualitative and quantitative analyses were correlated with each other to draw suitable conclusions.

5. ANALYSIS- BUILDING USAGE OCCUPANTS’ PERCEPTION

AND

The usage of the occupants differs depending on their age and culture. In this period outdoor dry bulb temperature was less than 16° C on an average during midday, and there was precipitation for a couple of days. All the ventilators in the living/dining space were closed during most of the time in the day. Qualitative analysis by means of interview of the occupants helped determine the usage pattern of the house is mostly unoccupied from 09:00 to 13:00 hours and from 14:00 to 18:00 Hours. The bedrooms are unoccupied from 08:00 to 21:00 hours. Overall the occupants are satisfied with the daylight, ventilation and thermal performance of the house. The occupants feel that due to the stack effect and

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

the sunspace the interiors spaces are thermally comfortable to stay. 5.1. On site temperature measurements The building is being monitored for different variables such as temperature, relative humidity, solar radiation and ventilation through the Webrick system. The system also records the occupancy patterns. Figure 10, Figure 11 and figure 12 show the indoor temperatures recorded in the two bedrooms in the first floor of the house, on 3 different days during the survey period. The comfort range has been marked between 20°C to 25°C for the study. The images clearly show that indoor temperatures are well above the external temperatures and show a steady temperature curve. The results have been discussed in detail in the summary below.

Figure 11 Temperatures recorded on 31st March 2009. (Source: Author)

Figure 12 Temperatures recorded on 1st April 2009. (Source: Author)

higher occupancy gains. This can be related to the usage pattern of the external ventilator adjacent to the bedroom zone. The exterior ventilator adjacent to the south west bedroom was open at least 5 hours for a day during the survey period, but the exterior ventilator adjacent to the South east bedroom was never left open during the survey period. Inferring Measurements taken from site, it is clear that the ventilators and doors (I/O) have been used in an optimum rate by the users to achieve comfortable indoor air temperatures (during spring) in most of the habitable spaces of the home during the survey period. However, the south east bedroom records temperatures more than 25°C for more than 4 hours in the daytime during the survey days; see figure 14, 15 and 16. Current observations show that there are hazards of overheating during summer with the current ventilator usage. Hence, the exterior ventilators in the south buffer space have to be operated to prevent overheating during summer. Comparing the measurements on site it is clear that the PCM used in the internal walls and the ground air heat exchanger contributes to maintain a steady internal temperature all through the day. The internal temperatures in the bedrooms are predominantly falling under comfort range. But according to UK good building practice guide for naturally ventilated buildings, the internal temperatures of habitable spaces should not exceed more than 25°C for more than 5% of occupied time. In the graphs it is clearly seen that the south east bedroom records temperatures more than 25°C for more than 4 hours a day during the survey days (in spring). Hence with the current ventilation pattern, there are hazards of overheating in summer. The south west bedroom seems to be working fine in the current usage pattern of the ventilators for spring. In order to improve the performance of the south east bedroom the exterior ventilators in the sunspace, adjacent to the south east bed room could be opened for at least 2hours in the day will bring down this zone’s temperature to comfort levels during spring time. During summer, the house has been designed to rely much more on natural ventilation. Hence the usage pattern for summer has to be different to keep the home within comfort range.

7. CONCLUSION th

Figure 13 Case1 Temperatures recorded on 4 April 2009 (Source: Author)

6. SUMMARY Irrespective of the outdoor weather conditions, the indoor temperatures in the living and dining area were warm and comfortable, showed temperatures ranging from 22°C to 24°C. The solar area showed temperatures above 27°C during midday, as expected. It was taking advantage of the direct solar gains. The Internal temperatures of the bedrooms predominantly fall in the comfort range, in spite of the low external temperatures. The south east bedroom records higher temperature compared to the south west bedroom, in spite of the fact that the south west bedroom is used by two occupants, which means

The aim of this study was to study the effect of the occupants’ usage pattern on the efficiency of a high performance building. The usage pattern of occupants of the BASF House, with respect to controlling openings in the house for thermal comfort th th was studied from 26 March to 7 April 2009. The period of this study falls under spring season in the UK. Qualitative analysis by means of interviews was used to measure the satisfaction level of the occupants. This analysis was correlated with quantitative analysis of performance data including temperature variations in the house collected by the Wetbrick monitoring system. Comparing the temperature profiles in the bedrooms and correlating them against the indoor temperature profiles clearly indicate the user’s

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influence on the thermal performance of the house. The analysis shows that, with the current usage pattern there is potential overheating of the house during summer. Opening the external ventilators in the sunspace during summer will reduce overheating. The house is designed to rely more on natural ventilation during summers. Hence the usage pattern in summer should accordingly change taking the comfort levels into consideration. From this study, it is evident that user’s intervention in controlling the internal environment is an important factor to be considered in architectural design. If a building is only designed and built by blindly following the recommended design guidelines and technical data without considering the human factor, an undesirable living environment will be created and it can be potentially counter-productive for energy conservation.

8. REFERENCES [1] www.house.basf.co.uk [20th May 2009] [2] http://www.nottingham.ac.uk/sbe/creative_energ y_homes/ [20th May 2009] [3] http://www.basf.de/en/uk/house/pressreleases/p m.htm?pmid=3189&id=V00-RELFbE7t3bw2.xk [20th May 2009] [4] http://www.energyefficiency.basf.com/ecp1/Ener gyEfficiency/en_GB/content/show_houses/UK/0 3_The_Site/The_Site [5] CIBSE TM 36, 2005. Climate change and the indoor environment of buildings. United Kingdom: Charted institution of building services engineers. [6] Rosa Schiano-Phan1*, Brian Ford1, Mark Gillott1, Lucélia T Rodrigues1, “The Passivhaus standard in the UK: Is it desirable? Is it achievable?”: Papers delivered at PLEA 2008 – 25th Conference on Passive and Low Energy Architecture, Dublin, 22nd to 24th October 2008 [7] Lucélia T Rodrigues, Dr Rosa Schiano-phan “Thermal Analysis of the BASF house” Report submitted to the University of Nottingham, Reg. Creative energy homes project.

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Design Tools for Architects: The Meaning of Solar and Daylight Access Information in Design Isaac Guedi CAPELUTO Climate and Energy Lab in Architecture, Faculty of Architecture and Town Planning Technion – Israel Institute of Technology, Technion City, Haifa 32000, Israel

ABSTRACT: During the conceptual design phase of urban areas, the designer deals with different geometrical characteristics related to the buildings’ orientation, height and width, in relation to open spaces and pedestrian sidewalks. New buildings may create a different microclimate, like changing the wind regime, daylight access and shading of existing neighborhoods. Protecting solar and daylight rights is a complex task, strongly influenced by early decision made by the designer. It is imperative that design tools could support architects from the beginning of the design process. However, existing design tools are still rudimentary with many limitations for use by designers in early design stages of any architectural project. They generally are aimed to external consultants and require exact data in a stage when designers consider conceptual ideas from a range of options rather than precise details and numbers. Design tools that suggest solutions based on ideas are rare. The paper presents several approaches for design tools for architects to support the entire design process. Moreover this work will demonstrate how existing modeling tools, widely used by architects for modeling purposes only, can be easily enhanced presenting information with a new meaning most valuable for design generation, giving architects new ways to make informed design decision towards high-performance architectural and urban design. Keywords: Design tools, Performance, Daylight Access, Solar Rights

1. INTRODUCTION The early stages of the architectural design process characterize themselves by a constant search for a design direction. But as demonstrated by specialists in design methods, decisions taken in those moments can determine the success or failure of the end product. The determination of a preferable design solution becomes specially complicated due to mutual influences. For example, the orientation and proportions of streets will influence the exposure of sidewalks to the winter sun, as well as creating the required shading during summer. On the other hand, ignoring the solar rights at the stage of the preparation of a master plan may cause unrepairable discomfort conditions around and inside the buildings, and seriously compromise their energy performance. The early stages of this process characterize themselves by a constant search for a design direction. But decisions taken in those moments can determine the success or failure of the proposed project. 1.1. Passive Solar Design The idea of ensuring solar access is not new; the Roman Empire had solar access laws; the "Leyes de Indias" (The Law of the Indies) that were applied on the foundation of new towns in America consider block layout and street orientation to allow solar access, and the Doctrine of Ancient Lights protected landowners' rights to light in nineteenth-century Britain. Many cities and countries in the world defined regulations to keep solar rights. Some were created from a public point of view to keep open spaces and sidewalks insolated as defined in cities

such as New York [1], San Francisco [2] and Toronto [3], [4]. In other places, regulations were defined to ensure the full use of private properties such as private open spaces and solar collectors. Additionally, several U.S. communities adopted solar access regulations in response to the energy crisis and as a way to save energy and reduce air pollution and costs. In Israel, the planning authorities of Tel Aviv Municipality adopted solar envelopes as a tool for urban development in a new business district [5]. In these examples, daylight and solar radiation are considered as significant factors in the determination of urban development policies. The importance of solar insolation in winter has been studied in many research works. The consideration of solar rights in urban design is essential in order to allow passive heating of buildings in winter and to improve the comfort conditions of people in streets, sidewalks and open spaces. It can reduce the energy consumption of the building if used indoors, while insolation of exterior spaces may create climatically comfortable areas which can be used for outside activities in winter. On the other hand, shading should be provided in order to avoid overheating of buildings and create pleasant spaces during summer. 1.2. Active Solar Systems Furthermore, interest in the building integration of solar systems, like solar water heating (compulsory for residential buildings in Israel) or photovoltaics panels, where these systems actually become an integral part of the building envelope often serving as the exterior weather skin, is growing worldwide.

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The local urban environment, location of collectors on different building surfaces and with different tilt angles, may affect the system performance, and as well the period of time over the year that they will be exposed to direct solar radiation. Since the amount of unobstructed solar radiation is critical to the efficient operation of solar systems in new or existing buildings as a part of roofs or building facades, the solar access to the collectors and the solar rights must be assured yearround. 1.3. Daylight Access Lighting is responsible for 30% to 50% of all the energy utilized in commercial and office buildings. Daylight can be used to reduce lighting energy use and the heat gains associated with electric lighting. The efficient utilization of daylighting can dramatically reduce the total electricity load and the peak demand. However, the availability of daylight in certain areas of the city can be difficult due to the influence of the external built environment. In medium and high density zones, where generally office buildings are located, the lack of light from the sky at street level can cause design problems for the architect that wishes to use daylight to provide a high quality working environment and as an energy efficient design strategy. Tall buildings and elongated obstructions can affect dramatically the amount of light received and its distribution inside the building [6], [7]. Given that only the upper floor in multi-story buildings can eventually make use of skylights, generally the only source of daylighting inside the office space is through side windows. In addition, the provision of side-daylit offices places limitations on building depth and interior organization. In dense urban areas buildings‘ arrangement is the most important factor affecting daylighting as well as the thermal comfort of public and private open spaces. The surrounding built environment can seriously affect the possibility of using daylight inside offices.

envelopes allowing daylight access. Schiler and UenFang [13] developed a computer program for the generation of solar envelopes for flat-rectangular sites based on Knowles work, and Koester [14] presented energy armatures using passive resources like winds and rain water, for urban sustainable development. The model SustArc developed by Capeluto and Shaviv [15] uses the Solar Rights Envelope (SRE), Solar Collect Envelope (SCE) and Solar Volume (SV) data as target functions (Fig. 1). These solar envelopes define the space of all possible design solutions that either considers solar insolation or solar shading. SustArc allows the generation of different building configurations, ensuring solar rights of each neighboring building, and open spaces like sidewalks, gardens and squares. The model presents the maximum available volume in which it is possible to build without violating the solar rights of any existing building, as well as the designed one. The Solar Rights Envelope presents the maximum buildings' heights that do not violate the solar rights of any existing buildings, during a given period of the year. The Solar Collection Envelope presents the lowest possible locus of windows and passive solar collectors on the considered building's envelope, so that they are not shaded by the existing neighboring buildings, during a given period of winter. Clearly, it is possible to determine the volume between both envelopes. This volume is called the ‗solar volume‘ (SV), and can be defined as follows: The Solar Volume contains the maximum buildings' volume to be designed so that these buildings allow solar access to all the surrounding buildings, and at the same time are not shaded by them, during a given period of the year (Fig. 1).

2. DESIGN TOOLS Different design tools for solar rights and daylight access were developed. Broadly, we can classify these tools into generation tools and evaluation tools. Generation tools aid to define the proper geometry to achieve a certain performance. Performance-driven form generation refers to the idea that performance data can be used to generate architectural form. Shaviv [8] proposed a method and a computerized model for the design of fixed external sunshades. The method was extended later for the generation of solar rights envelope for the design of solar communities [9]. Arumi [10] developed a computerized model that determines the maximum allowed height of a building that does not violate the solar rights of the existing neighboring buildings. Knowles [11] suggested a method for assuring solar access to each residential unit in a community. De Kay [12] made a comparative analysis of various

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Figure 1: Solar Envelopes: Solar Rights Envelope (1), Solar Collection Envelope (2), and Solar Volume

Evaluation tools, on the other hand, analyse the performance of a given design alternative. Although architectural design processes ends up with a single built design, during the design process numerous design alternatives are generally created and evaluated. Examining several design alternatives meant that labour had to be dedicated to the creation of every singular design alternative. As architectural design is often performed under tight schedule and

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

budget, the amount of resources designers have to investigate design alternatives is highly limited. In practice, the large majority of existing evaluation models is geared to simulate and evaluate finished alternatives. According to Ochoa and Capeluto [16] they are unsuitable as practical design aids for architects, since they share the following characteristics: • Not all of them follow the logic of the architectural design process, which involves an iterative and sometimes loose method based on incoming information, stated principles and mental schemes. • Early design decisions are based on vague ―ideas‖ that cannot be evaluated with tools that rely on exact data. They require complex input procedures, together with translations from one format type to another. • The majority of evaluation programs are designed for use by consultants, generally engineering companies that enter the design field very late, when main geometric characteristics of the building are already fixed. • Input of current evaluation models needs detailed information and precision not known and not relevant at the beginning. Tools can also have complex interfaces that require much time to learn and use. Both factors can distract from the design activity itself. • Most tools are dedicated to evaluate and model a certain finished alternative, not to suggest and evaluate different design options and directions. This implies fitting an idea to the modelling tool, thus filtering out information that could be useful or distorting the process. • Architects trying to use these tools are thus subject to evaluate finished alternatives using a trial and error approach. This slows down production schedules or forces to depend exclusively on factual experience. • For complex projects on the boundary of his or her expertise, the designer has few criteria about which design direction to develop in order to pass from idea to concept. In the next sections we will introduce and demonstrate the application of SunTools [17], implemented using Ruby scripting language as a plug-in for the Sketch-Up modelling program [18], which allows visualization of sun position and the sun path; produces axonometric views from the sun to easily analyze mutual shading and solar access and penetration at any design stage (Fig. 2), providing evaluation results that can be used as generative information. The analyses are easily done without the need of exporting the geometric data to external programs, using the same existing 3D model. We will discuss as well, new developments that allow using evaluation of solar irradiance in complex urban environments as a design tool, as part of the toolbox available to designers. These tools aim to serve students, teachers, architects and consultants from the early design stages, to include solar consideration in the design.

3. MEANING OF INFORMATION IN DESIGN SunTools was developed as an attempt to investigate the possibility of using existing design tools, widely used by architects, providing the designer all along the design process with new performative information that can help him in the generation of design solutions. 3.1. Sun Path and Sun Position The key to designing a successful passive solar building is to best take advantage of local environmental conditions and climate. The ability to improve building performance and comfort as well as the quality of open spaces in winter and summer is fundamentally dependent on the understanding of the seasonal variations in the sun's path throughout the day in relation to the designed building. Fortunately common modelling tools widely used nowadays by architects very early in the design process provide capabilities of visualization of accurate shadow casting by the design during various times of the year. This feature allows quick visualization and understanding of mutual influences among buildings at certain times. However, these tools generally do not allow visualizing the sun itself despite that they calculate internally its relative position in the sky, according to the geographical definitions of the model. Visualizing the sun path during a required period of the year or at a certain date and time can help to better understand the impact of the sun in relation to the project and its surrounding areas. Since this information exists in the model is very simple exposing it to the designer creating a new layer of information to work with (Fig. 2).

Figure 2: Sun Path and Sun Position visualization in SunTools as part of the model

3.2. Sun Penetration Once the solar geometry information was incorporated as part of the working model it can be manipulated in order to perform evaluations of the design proposals. Using this information SunTools

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allows assessing Sun Penetration and Solar Access at any specific point of the project (Fig. 3). This powerful evaluation is produced taking advantage of common capabilities of modeling tools of producing custom views from pre-set viewing points and directions.

Figure 3: Solar Access in open spaces as evaluated using SunTools

The evaluation allows designers using their own 3D working models understanding in one comprehensive view the periods of exposure and shading for the analyzed position in the project. Furthermore, the designer can see and understand the causes of overshadowing and modify accordingly the design in order to obtain the desired performance. This feature can be applied to study Sun Penetration inside buildings, as shown in Fig. 4. The geometry of the shading devices can be modified interactively as necessary to protect the building as required.

Figure 4: Assessing Solar Penetration inside an office building (up) and modifying sunshades dimension according to required performance (down).

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3.3. Sky View In a well-designed space, daylight reduces energy costs, enhances the visual quality, and provides others psychological benefits that are hard and expensive to imitate with electrical lighting. The availability of daylighting in certain areas of the city can be difficult due to the influence of the external built environment. The surrounding built environment can seriously affect the possibility of using daylighting inside buildings and compromise daylight availability at street level. The penetration of daylight into the building depends on many design parameters, among them the depth of the room from the window wall, ceiling height, internal reflectances, window orientation, shape and size, and optical properties of the glazing. It must be stated that most of these factors are unknown by the designer at the early design stages. However, the most significant factor is the availability of daylight outside the building which can be seriously affected by external obstructions like neighboring buildings or trees. According to Capeluto [6], the sky solid angle (SSA) presents the solid angle subtended by the path of the sky visible from the studied point. The SSA is proposed as a means to assess the influence of the external obstructions on the availability of daylighting inside buildings. There exist a correlation between the SSA and the DFave, serving as an indicator of the daylighting potential of the site. The solid angle subtended by a surface is defined as the surface area of a unit sphere covered by the surface‘s projection onto the sphere. This method can help architects consider, evaluate and as a consequence make design decisions by keeping in mind the daylighting potential (or limitations) of the site, and its implications on building design. It can provide also valuable information for authorities trying to regulate development in a way that considers daylight as a key for urban development and ensures an acceptable access to light for different city zones. With SunTools, the SSA can be easily determined using the 3D model that contains the volumetric information of the studied built environment. The method consists in tracing rays from the studied point in all directions to the sky vault and determining if it is visible or obstructed from this position. In this way the SSA and the percentage of the visible and obstructed sky can be calculated. Moreover, the visible and/or obstructed part of the sky vault can be visualizes as part of the working model. Supplementary information can be super imposed to provide extra information to the designer as seen in Fig. 5(down) and Fig. 6 showing together sun paths and visible sky vault.

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 5: Visible (and obstructed) part of the sky vault as determined by SunTools

Figure 6: Visible sky vault and combination with sun paths

4. CONCLUSION This paper discusses the meaning and value of performative information presented to designers during their work throughout the different stages of the design process. It presents different approaches for design tools for architects allowing generation and evaluation of design solutions. It demonstrate through the development of SunTools, a plug-in for SketchUp, how existing design tools can be enhanced in order to overcome limitations of existing tools and provide architects with evaluations that have generative value using the same 3D working model. Using the same model for performing the evaluations allows making changes interactively to improve and adapt the design to a required performance. SunTools is being extended to include evaluations of additional subjects as new layers of information that may contribute to generate design based on solar and daylight access Information.

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5. REFERENCES [1] New York City, Departmnet of City Planning website: http://www.ci.nyc.ny.us/html/dcp/ [2] San Francisco Planning department website: http://www.sf-planning.org/ [3] Bosselmann P., E. Arens, K. Dunker and R. Wright. ―Sun, Wind, and Pedestrian Comfort. A Study of Toronto‘s Central Area.‖ Center for Environmental Design Research, University of California at Berkeley and Centre for Lanscape Architecture Research, University of Toronto. The Dept. of Planning and Development, City of Toronto (1991). [4] Brown, J., K. Storey, B. Jin and D. Lago, The Open Spaces of Toronto. A Classification. Final Report, Prepared for the City of Toronto, Dept. of Planning and Development (1991). [5] Capeluto I.G., A. Yezioro and E. Shaviv, 2003. "Climatic Aspects in Urban Design – A Case Study", Building and Environment (2003), 38(6):827-835. [6] Capeluto, I.G., The influence of the urban environment on the availability of daylighting in office buildings in Israel. Building and Environment (2003), 38(5):745-752. [7] Li, D.H.W., Wong, S.L., Tsang C.L., and Cheung, G.H.W, A study of the daylighting performance and energy use in heavily obstructed residential buildings via computer simulation techniques. Energy and Buildings (2006), 38(11):1343-1348. [8] Shaviv E. A method for the design of fixed external sunshades. In Build International (1975), 8:121-150, Applied Science Publishers, UK. [9] Shaviv E. Design tools for solar rights and sunshades determination. In Proceedings of the Ninth National Passive Solar Conference, ASES, Boulder, CO, (1984):14–19.

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[10] Arumi F. In Computer-aided Energy Design For Buildings. Energy Conservation Through Building Design, Watson D. (Ed.), McGraw-Hill, NY (1979). [11] Knowles R. L.. Sun Rhythm Form, The MIT Press, Cambridge, MA. (1981). [12] De Kay M. A comparative review of daylight planning tools and a rule-of-thumb for street width to building height ratio. In Proceedings of the 17th National Passive Solar Conference — ASES, Boulder, CO. (1992). [13] Schiler M. and Uen-Fang P. Solvelope: an interactive computer program for defining and drawing solar enveDlopes. In Proceedings of the 18th National Passive Solar Confer- ence — ASES, Washington, D.C. (1993). [14] Koester R. J. Energy armatures — ordering an integration of passive energy resources for community sustainability. In Proceedings of the 19th National Passive Solar Conference — ASES, San Jose, CA. (1994). [15] Capeluto, I.G. Shaviv, E. On the Use of Solar Volume for Determining the Urban Fabric. Solar Energy (2001), 70(3):275-280. [16] Ochoa C.E, and I.G. Capeluto, 2009. "Advice Tool for Early Design Stages of Intelligent Facades based on Energy and Visual Comfort Approach", "Energy and Buildings" journal, Vol. 41 pp 480-488, Elsevier Science Ltd., doi:10.1016/j.enbuild.2008.11.015 [17] SunTools plug-in website: http://tx.technion.ac.il/~arrguedi/SunTools/downl oad.html [18] Google Sketch-Up website: http://sketchup.google.com/

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Daylight evaluation of retrofitting methods: Conversion of the ‘Spierer’ tobacco warehouse in Volos, Greece. Polytimi ILia Environment & Energy Studies Programme, Architectural Association School of Architecture, London, UK ABSTRACT: This analysis begins with a broad discussion of typical tobacco warehouses’ typology and the ways in which this typology can be modified throughout an environmental daylight retrofitting conversion. Specifically, the study focuses on cases linked to the Mediterranean region, and mainly to warehouses in Greece. Besides, the analysis incorporates the proposal of a series of environmental methods for improving daylight conditions. A generic case study in Volos is introduced to the analysis; the ‘Spierer’ Tobacco Warehouse. Through intensive research, fieldwork, and analysis in the form of daylight simulations, various conclusions will be drawn with regard to structure’s alteration and environmental performance. According to the final conclusion, the initially proposed hypothesis will be verified. Particularly, it will be concluded that old tobacco warehouses which are converted into multi-purposed spaces can be transformed architecturally in a way that satisfies the new visual occupancy requirements in a Mediterranean climate and consequently, energy consumption can be reduced through the implementation of a number of specific interventions. The following paper is based on my MSc Dissertation in Sustainable Environmental Design undertaken at the AA School of Architecture. The outcome of the following research could comprise a useful tool for both architects and environmental engineers working in the field of sustainable design. Keywords: tobacco warehouse, retrofitting, intervention, daylight, occupant visual comfort

1. INTRODUCTION Greece is a country with valuable cultural heritage, whose traditional industrial buildings comprise a substantial component of its historical legacy. These traditional buildings are typically listed as cultural heritage sites in Greece and are usually protected (Fig.1). Buildings with this peculiar designation have to be preserved in their original pattern, without distorting their external architectural appearance during any kind of renovation. This governmental limitation combined with any current architectural need, provides an exceptional chance for conversion. Throughout this conversion, a number of interventions have to take place with regard to the building’s daylight performance, as a different occupancy and usage usually demands different conditions. These interventions typically influence a building’s energy performance and daylight levels.

warehouse located in Volos on the central mainland of Greece. This study will seek to give answer to the following query: Can the old tobacco warehouses, which are converted into public multi-purposed spaces, be transformed architecturally in a way that satisfies the new visual occupancy requirements in a Mediterranean climate?

2. THEORETICAL BACKGROUND 2.1. Architectural contribution warehouse typology

to

tobacco

Figure 1: Listed tobacco warehouse buildings in Greece. [1]

For the purpose of further investigation, a generic case study has been chosen as the most convenient tool for carrying out this type of analysis. The case study concerns the ‘Spierer’ tobacco

Figure 2: Representative tobacco warehouse typology. Erman Spierer tobacco warehouse (1925). [1]

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In Greece, Thessaloniki, Volos and Agrinio were some of the first tobacco centres developed around the end of the 16th century [2]. Due to the needs of a growing tobacco industry in Greece, a considerable number of tobacco warehouses were built to accommodate the increasing needs for tobacco processing and storage. The architectural oeuvre of Austrian engineer Konrad Jacob Josef von Vilas played a major role in the architectural style of cities known as tobacco centres in Northern Greece [2]. For this reason, a representative example of his work is used in order to define the architectural tobacco warehouse typology (Fig.2). 2.2. Occupancy Pattern The distribution of occupancy is determined by the architectural design of tobacco warehouse building [1]. The storeys of tobacco warehouses all include a semi-basement, intermediate storeys, and an attic. Windows’ size and stories’ height are different on each floor depending on the needs of their main occupancy. At the floors of lower heights (smaller windows) raw tobacco was stored, while at the floors of higher heights (bigger windows) the tobacco production process was taken place (Fig.3), where workers were sitting on the floor positioned very close to the perimetrical walls, trying to take advantage of the increased daylight levels which were provided by a high window-to-wall ratio. Not only the distribution of space, but also the occupants’ schedule demonstrates the significance of visual comfort to tobacco production [2].

The applied retrofitting methods have to be set on a hierarchy (Fig.4), in terms of their intervention degree on a traditional building, according to the following innovative classification: 1.Mild Methods, 2.Conventional Methods, 3.Advanced Methods.

3. CONTEXT AND CLIMATE CONSIDERATIONS Volos is located in the centre of Greek mainland and is built on the innermost point of the Pagasetic Gulf. In latest decades, Volos reflects remarkable achievements in the maintenance of local heritage with regard to city’s old industrial structures. There are architectural organisations in progress that seek to preserve these structures by accommodating modern uses to retrofitted buildings that serve public needs [4]. The goal of this inspiration is to generate sustainable and energy-efficient buildings. Volos experiences a moderate climate with evident distinction of seasons, as it is a Mediterranean city (Fig.5). The most frequent sky condition is sunny sky with sun [5]. It is declared that spaces need to be protected from the extreme solar radiation during summer, when buildings’ vertical surfaces are shaded while horizontal are exposed. In such climates, this can be accomplished by using shutters or else light shelves placed in front of panes to avoid solar gains [6].

Figure 5: Monthly average values for air temperature, daylight hours and cloud cover. Volos, Greece. [7]

4. CASE STUDY Figure 3: Occupancy pattern of tobacco warehouses according to function requirements. Section. [1]

2.3. Environmental Retrofitting Methods

4.1. Building Description ‘Spierer’ tobacco warehouse is situated in the centre of Volos (Fig.6).

Building conversion projects must align with the new occupancy pattern, as a matter of prime importance to a building’s energy consumption [3]. Figure 6: ‘Spierer’ tobacco warehouse building under study. General external views.

It was designed by Konrad Jacob Josef von Vilas in 1927. ‘Spierer’ building was restored at about 1998 and nowadays it accommodates the Municipal Cultural Centre of city. Presently, ground and second floor accommodate public service offices, first floor serves architectural studios, while an exhibition space is provided in the attic floor (Fig.6,7). Figure 4: Innovative classification of daylight retrofitting methods.

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temperature remains low. By and large, shutters are separated into two or four parts (depending on the storey), they are dark and made by wood. Therefore, occupants have the opportunity to control the shutters depending on the needs of their activity and the climatic conditions of each season. 4.3. Architectural changes resulting from the environmental retrofitting and the new occupancy pattern The reform of the uniform tobacco space into new sub-space environments is a fundamental mild change during the conversion. This internal architectural space distribution required the creation of both public and private spaces, since the in question building needed to be converted into a multi-purpose space with diverse schedules and occupants (Fig.9).

Figure 9: Mapping of public and private zones at each floor.

Figure 7: ‘Spierer’ tobacco warehouse building under study. Plans mapping the distributed occupancy at each floor. [1]

4.2. Typical architectural environmental value

features

of

Although tobacco warehouse is now converted into a multi-purposed building, it still contains some elements of typical industrial architecture. In terms of windows’ construction method, the parts of walls that contain windows are inclined in a way that provides gradient daylight distribution in the interior space (Fig.8). Thus, the daylight contrast between the internal wall surfaces (reduced daylight levels) and the outdoor illuminance (increased daylight levels) is reduced [8].

It seems that architects assigned the floors based on the frequency of each floors’ new function. The most advanced retrofitting intervention that was applied is the construction of two internal atriums aiming to enhance ventilation on each floor. Along with the initial building’s function, the daylight zones were considered to be exclusively the areas on the perimetrical sides (due to building’s compact and deep plan). The construction of atriums is combined with the application of rooflights on the attic storey as an additional applied retrofitting method for increased daylight distribution, improving drastically the new occupants’ visual comfort (Fig.10).

Figure 10: Atriums’ and rooflights’ applications at ‘Spierer’ building. Advanced daylight retrofitting methods. [1]

Figure 8: Splayed reveal windows. On-site sketches.

In the case of ‘Spierer’ tobacco warehouse, every window on each facade has shutters which provide solar control and keep the space dark while the

Subsequently, the architectural space distribution of the various functions is determined by the addition of the two atriums. The atriums are part of the circulation zone in public areas, where people are in transit. Each storey has different layout depending on the distribution of space. Each atrium is adjacent to a different space on each storey and every side of each atrium may also have a different type of adjacency. The sort of adjacency proclaims the degree of atrium’s impact, giving out the

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environmental and the applied architectural design. (Fig.11)

Figure 11: Architectural types of adjacency between spaces and atriums. Innovative classification.

Therefore, it is worth investigating the relationship between the designed atriums and their adjacent spaces. Thus, the architectural manipulation of atriums’ side borders can be worked out in order to determine if there was any strong initial environmental concept on which the architectural design was based. Besides, the nature of environments that were created after the implementation of atriums is explored in order to classify these areas. The architectural concept corresponds to the function and occupancy requirements of each attached space to the atrium. For instance, public spaces such as transitional and exhibition spaces can be categorized as cases of Natural Access. In these cases, the main function of atrium is not only to enhance the daylight levels, but also to improve the airflow in each storey. These constitute open spaces that both serve the moving of occupants from one office to another and are used during the occupants’ break times. On the other hand, private spaces usually border atriums’ sides by offering Optical Perception while acoustic problems are deterred. It has been observed that strictly private spaces require Semi-Optical Perception in order to keep concentration at the greatest possible extent (with additional manual control of blinds), while at the same time the daylight is being also offered at the greatest extent on the working plane. Private spaces that have uncertain use, such as lounge spaces, have side borders that offer Optical Perception with Full Glazing directly adjacent to the atrium. In some of the offices, air circulation through the clerestories can be expected. (Fig.11) 4.4. Quantitative Measurements)

Approach

(On-site

Aiming to recognise and clarify the way in which the daylighting source interacts with the building’s renovated architecture, the on-site measurements have been studied through plans and sections. In terms of daylight performance on typical floors, measurements show that storeys are inadequately lit from daylight in most of building’s sub-spaces. Therefore, daylight penetration is not sufficient for visual task requirements [9], since the daylight incoming from the roof has hardly reached the lower floors due to the atriums’ small dimensions. The transitional space is also dark apart from the areas

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around the atriums which are bright but create visual discomfort due to daylight contrasts. (Fig.12) With reference to daylight performance on attic level, it is demonstrated that the uniform attic space is naturally lit at the maximum of the surface, in terms of the plan. The daylight penetrates the space and creates a kind of homogeneous light at the working plane (90cm). The direct solar radiation contributes to the creation of notable sun patches which generate visual discomfort for occupants, especially those occupied in the space around the atriums. According to occupants, this discomfort due to the glare contrast results to the use of electrical lighting throughout the year, even though there are adequate lighting levels during summer sunny days. The intermediate zone between the southwest wall and the atriums stays dark regardless of the sky conditions. Empirical methods have been applied to control the indoor daylight performance such as putting bright vertical surfaces (sheets) in front of areas to reduce the daylight surface contrasts. No shading control is observed on the rooflights. (Fig.12)

st

Figure 12: (Top) Mapping showing daylight distribution at 1 floor and attic floor, derived from on-site measurements. (Bottom) Daylight penetration at the spaces.

5. DAYLIGHT PARAMETRIC STUDIES Throughout the on-site measurements, it was found that several problems occurred in the point of daylight performance of the in question renovated building. Thus, it would be beneficial to quest for an optimal final design proposal [10]. For this purpose, there will be indicated a number of sequential implemented interventions. • Base Heritage Case (Conventional retrofitting method): The daylight building performance will be calculated after the rehabilitation of the tobacco warehouse by re-opening all the perimetrical apertures. After the rehabilitation of the windows has been implemented, the daylight effect will be in specific areas. (Fig.13)

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 13: Daylight effect distribution by re-opening all perimetrical windows (Base Heritage Case). Simulations by using Radiance [11].

• Case 1: Base Heritage Case + Atriums bridges’ removal (attic floor) (Conventional retrofitting method): In terms of the plan, it is observed that the effect of this intervention influences the daylight distribution on all floors, improving the daylight levels even on the ground floor. (Fig.14)

Figure 14: Daylight effect distribution by removing the atriums’ bridges (Case 1).Simulations by using Radiance[11]

• Case 2: Case 1 + Exchange of occupancy on the 1st floor and in the attic (Conventional retrofitting method): After exchanging the uses between the 1st floor and the attic, and after removing the internal partitions, it is proved that the lack of internal partitions improves the daylight distribution on the floors. Rooflights are able to give as much daylight as possible and all areas under this configuration can be lit by natural means. (Fig.15)

Figure 15: Proposed exchange of functions’ distribution st between 1 floor and attic floor. (Case 2)

• Case 3: Case 2 + Atriums’ and rooflights’ doubled size (Advanced retrofitting methods): The building is tested in section in order to see the effect of rooflights on all floors. It is observed that the effect of rooflights during the autumn equinox and the winter solstice is small on lower floors.

Figure 16: Daylight effect distribution by duplicating atriums’ and rooflights’ dimensions (Case 3).Simulations by using Radiance [11].

During summer solstice, it is shown that daylight reaches the ground floor but solar gains are increased and the space is overheated; which is undesirable result. By increasing rooflights’ dimensions, the issue of daylight distribution is not solved to a remarkable extent since the daylight distribution remains more or less the same in terms of plan (Fig.16). However, daylight adaptability can be improved since daylight sources are increased

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and therefore the gloomy areas in the space are decreased. • Case 4: Case 3 + Shading roof protection (Conventional retrofitting method): The addition of internal shading controls (white fabric) in front of rooflights is a necessary intervention for a Mediterranean climate, especially during warm periods. This is not only for regulating the daylight quality of the space, but also for eliminating the penetration of solar gains, fact that consequently contributes to the reduction of cooling loads. Therefore, occupant’s control can offer the appropriate internal daylight conditions, according to occupancy requirements. (Fig.17)

occupants’ visual comfort. Finally, the removal of internal partitions enhances the daylight distribution of tobacco warehouses; fact that is highly dependent on the new occupancy requirements (in terms of spatial distribution). Uniform spaces usually have flexible uses and thus can be easily amended into tobacco warehouses under the condition to achieve the most appropriate distribution for the best building’s energy efficiency. To conclude, the initial hypothesis has been verified through the conducted analysis. It can therefore be asserted that old tobacco warehouses which are converted into public multi-purposed spaces can be transformed architecturally in a way that satisfies the new visual occupancy requirements in a Mediterranean climate. Above all, the implementation of deliberate interventions contributes to a further reduction of the converted building’s lighting consumption.

7. ACKNOWLEDGEMENTS

Figure 17: Simulated daylight with and without rooflight control, by using Radiance [11]. Attic floor. (Case 4)

First and foremost, I would like to express my gratitude to Professor Simos Yannas for helping me to draw the foundation of this dissertation. I would also like to acknowledge and thank Maria Ampatzi, for offering insightful recommendations and advice during the dissertation period.

6. CONCLUSIONS

8. REFERENCES

The key purpose of this study was to present a descriptive analysis of various retrofitting methods and to record the repercussions of ‘Spierer’ tobacco warehouse conversion in Volos. The conversion of Greek traditional industrial heritage through retrofitting methods is one of the most discussed topics in the environmental milieu. Thus, the need to consider the impact of retrofitting concept on a traditional structure was evident, and formed the basis of the in question analysis. By studying the architectural typology of old industrial buildings on the mainland of Greece, it is obvious that the construction is directly related to occupancy pattern. However, the interventions on a traditional building must be gentle to the initial bearing structure. In terms of both daylighting and building’s heritage, it is concluded that the splayed reveal windows of tobacco warehouses improve building’s daylight performance, and energy can be saved by reducing lighting needs. In such cases, internal surfaces should also be of high reflectance for a brighter interior environment. Additionally, perimetrical windows contribute to daylight penetration exclusively on the perimetrical areas of each floor. The application of rooflights has notable contribution to daylight distribution for the deep plans of tobacco warehouses and functions to help meet the needed visual requirements within the building. Daylight efficiency of the proposed rooflights and atriums designs depends on the number of floors in the building. In summer, atriums’ and rooflights’ dimensions play a major role in building’s energy consumption, in Mediterranean climates. For this reason, shading control on the rooflights is necessary to adjust solar gains, and also to improve

[1] Ilia, P., (2010). “Thermal evaluation of retrofitting methods: Conversion of the ‘Spierer’ tobacco warehouse in Volos, Greece”. Passive & Low Energy Cooling for the Built Environment, Proc. of PALENC Conference. Rhodes. [2] Trakosopoulou-Tzimou, K., (2002). “The Architecture of Konrad Jacob von Vilas”. Municipality of Drama. Drama. [3] Richarz, C., Schulz, C., and Zeitler, F., (2007). “Energy-Efficiency Upgrades”. Die Deutsche Bibliothek. Berlin [4] ‘In Volos’, (2006). “Industrial Heritage in Magnesia”. Volos Municipality. Issue 23. OctoberDecember 2006. [5] Satel-Light, (2008). “The European Database of Daylight and Solar Radiation”. www.satel-light.com [6] Yannas, S., (1994). “Solar Energy and Housing Design”. Vol.1. Principles, Objectives Guidelines. Architectural Association, London. [7] Meteotest, (2008). “Meteonorm v6.0.2.5” Global Meteorological Database. Meteotest. Bern. [8] Oikonomou, A., Bougagioti, F., (2004). “Visual Behaviour of Traditional Architecture in the City of Florina in North-Western Greece”. Sustainable Architecture. Proc. Of PLEA Conference, Netherlands. [9] CIBSE (a), (2005). “Lighting Guide 7: Office Lighting CIBSE Publications Department”. The Society of Light and Lighting. England. [10] Ecotect v5.6, (2008). Square One / Autodek. [11] Radiance (2000). “Environmental Energy Technologies Division”. Lawrence Berkeley Nat. Lab.

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ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. ISBN xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

Effectiveness of Dynamic Daylighting Post Occupancy Evaluation of a Higher Ed Building Judy THEODORSON1, Julia DAY1 1

Interdisciplinary Design Institute, Washington State University, Spokane, U.S.A.

ABSTRACT: The resurgence of interest in daylighting in support of both energy efficiency and human factors presents the need to study daylit buildings within the context of occupation. This paper studies the effectiveness of a “state of the art” LEED Gold higher education classroom building in the US Inland Northwest. The design earned both the EQ 8.1 and EQ 8.2 credits for daylighting by employing a variety of strategies including sidelighting with automated shades in a double ventilated facade and toplighting in light wells for interior spaces. The research includes predictive performance, post occupancy field measurements, and a user survey. Field measures document daylight variability and product performance. The user survey probes issues of satisfaction with interior conditions and behaviours around system operations; it is adapted from IEA SHC Task 21 (1999). By triangulating physical evidence and occupant experience, a multi-faceted understanding of daylighting effectiveness emerges. Keywords: daylighting, post-occupancy evaluation, occupant, comfort

1. INTRODUCTION Architectural daylighting is emerging as a cornerstone strategy for low energy and high performance buildings. A building designed to utilise daylight has the potential to significantly reduce loads for electrical lighting and HVAC. Additionally, there are human benefits: a growing body of literature suggests the potential for improved human performance [1,2] and a strong relationship between natural light and favourable health outcomes [1,3]. Furthermore, natural light and views are highly desired and valued by occupants [1,5,6]. The welcome resurgence of daylit buildings presents opportunities to study emerging daylight practices. This paper specifically addresses the effectiveness of daylight strategies within the context of occupancy. The intent is to create a feedback loop that considers the end-user while advancing high performance daylighting design. There are inherent challenges in designing buildings that utilise natural light as the primary ambient lighting system. Daylight is a highly variable resource, changing in direction, intensity, and quality throughout the day and the year. Designers must also consider the thermal implications that accompany the introduction of natural light into a space. Successful daylighting requires integration of architecture, building systems, and specialised products. Interior daylight control systems must sense and adapt to the ever-changing luminous inputs, while accommodating a variety of programmatic functions. The interaction between the occupant and the system further complicates daylighting prediction and design; Hygge and Löfberg (1999) suggest that daylighting systems “will be successfully used only if the building occupants are satisfied with the indoor environment and the operation of the system.” [6] The object of study is a higher education classroom and office building located in a temperatecold climate in Washington State, USA. The building houses two academic departments and serves mostly

young adult students. The building achieved LEED 2.0 Gold certification and obtained EQ 8.1 and EQ 8.2, Daylighting and Views, through multiple daylighting strategies including sidelighting with an automated, dynamic blind system, and toplighting for interior spaces on the third floor. Two issues emerge that are of importance to this study: the concept of dynamic daylighting and interior daylight controls. Reinhart, Mardaljevic, & Rogers (2006) argue the current daylight metrics and prediction tools are focused on static circumstances and fail to capture the complexities of interactions between climate, building, and occupant [7]. Furthermore, the LEED metric does not consider qualitative aspects beyond elimination of sunlight. In the case of this project, the designers had to aggressively pursue all daylighting opportunities to meet the LEED requirements for EQ 8.1. Studies of daylight variability and consideration of climate forces ultimately led to the adoption of a dynamic daylighting scheme for the primary classrooms. The second topic significant to this study is the issue of daylight controls within the interior. Heschong (2010) noted that blinds in daylit spaces play an extremely important role, yet there is limited research that predicts how blinds are used and their influence on daylighting performance [8]. As this project utilises a state-of-the-art blind system, there is a unique opportunity to gain insight into both the user experience and the blinds’ effectiveness in achieving daylighting goals.

2. BACKGROUND 2.1. Design Intent This building project was intended to be an exemplar for sustainable higher education buildings, demonstrating contextual design and environmental responsibility. The design team had an integrated design perspective and a willingness to consider strategies that were innovative and untested in the region. The architectural vision was grounded in the

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concept of “learning lanterns.” The expansive double glazed facade was intended to visually connect the buildings’ classrooms “to the heart of campus while providing students with an opportunity to see a building interact with exterior climatic conditions.” The site dictated a southwest orientation for the primary lecture classrooms. This presented challenging climate conditions (low sun angle with potential for glare and overheating in the late afternoons). To mitigate climate forces while achieving daylight goals and visual connection, the architects implemented a multi-story double ventilated facade, described by the architects as a “thermal buffer wall” (Fig.1). The approximately 4’-0” interstitial space was designed to naturally vent heat through a two-story stack. To control the variability of natural light, a proprietary automated daylight system was installed in the cavity. The system adjusts the blinds in response to exterior climate sensors and occupancy schedules. User overrides are available, allowing occupants to control the blinds for light, views, and to accommodate teaching needs. As these building features -- double ventilated facade and automatic louvers -- had not been previously employed in region, there was interest in studying the daylighting effectiveness of the design.

perpendicular to the window wall. The small interior classrooms (C) are equipped with a south-facing lightwell at the back of the space, providing natural light to approximately 50% of the classroom area; the height of the lightwell provides daylight control. There are no view windows in these interior spaces. In all the classrooms, daylight harvesting is accomplished through a dimmable fluorescent lighting system.

 

  Figure 2: Section diagram of three classroom types

  Figure 3: Classroom type A, typ.

3. METHODOLOGY 3.1. Overview

Figure 1: Building section showing double ventilated facade, per architect.

2.2. Daylighting Strategies Three types of classrooms were evaluated for this study (Fig. 2). The perimeter classrooms on the third floor (A) and the second floor (B) utilise sidelighting for the perimeter zone. Daylight control is provided by the automated horizontal louvers in the ventilating cavity. The slats are reflective on both sides, for the purpose of daylight and heat re-direction. At eye level, the blinds are perforated to allow for a nominal exterior view when closed. The third floor classroom (Fig.3) has the added benefit of a northeast-facing clerestory, opposite the window wall, creating a balanced daylit environment. These spaces are lecture halls with tables-chairs arranged

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This applied research is the product of an on going initiative to bridge the academy and the profession through project based research and education specific to the emergent field of daylighting design. The intent is to build interdisciplinary knowledge that is mutually beneficial to all communities. This study implements multiple methods at various stages of design and occupation, including predictive performance modelling, field study, and a post-occupancy user survey. Systematic postoccupancy evaluation facilitates linkages between design processes, building performance and human responses. The voice of the occupant provides a unique perspective on how daylighting systems function over extended time periods with varying climatic conditions. Additionally, user views lend insight to what is valued within their work and teaching environments, and what is not. This paper specifically addresses three areas of inquiry: (a) effectiveness of daylighting strategies (b) interactive behaviours with daylighting system, and (c) satisfaction with daylighting as the primary ambient light source. 3.2. Daylighting Prediction and Design The criteria that provided the benchmark for the daylighting design was a “daylight factor of 2% with sunlight control” per LEED 2.0 E.Q 8.1. The WSU Daylighting and Integrated Design Lab was engaged during pre-design to conduct iterative daylighting

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studies with physical models. An artificial skybox provided testing circumstances for the overcast sky condition and verified the daylight factor requirement (Fig.4). Office windows, clerestories and light wells were developed and fine-tuned through this process. Diurnal and annual solar patterns were studied with a fixed-sun heliodon. The original idea was to control the southwest sun in the perimeter classrooms with fixed louvers in the thermal buffer wall. When testing demonstrated that this approach would be inadequate to control sunlight over annual conditions (Fig.5), the architects selected an automated dynamic louver system and worked with the product representatives to design appropriate algorithms and user overrides.

respondents completed the survey under sunny sky conditions. The overall response rate was 38% (n=22). Of these responses, there were 12 female (55%) and 10 male (45%) participants. The ages of respondents were reported as follows: (32%) above the age of 60 years, (27%) between the ages of 50 to 59 years, (32%) between the ages of 40 to 49 years, (9%) between the ages of 30 to 39 years, and no individuals (0%) were below the age of 30 years.

 

  Figure 4: Classroom A, daylight model in artificial skybox.

 

Figure 6: Sample illuminance readings across classrooms

  Figure 5: Daylight control testing in heliodon

  3.3. Post Occupancy Field Observations Graduate students conducted field research approximately two years after building completion. Data was collected from each classroom type through field measurements and during July (clear sky conditions) and October (mixed sky conditions). Field measurements recorded hourly illuminance data for each room type during typical occupied hours (Fig. 6). Observed data from the field study work includes photograph recordings of hourly interior shades positions. Additionally, HOBO data loggers collected illuminance, temperature and relative humidity readings for each room type for one week, under variable sky conditions in July. Data loggers were placed centrally within the space, near the window, and near the lightwell if one was present. 3.4. Post Occupancy User Survey An online questionnaire was administered to faculty members with both offices and teaching assignments in the building. Responses were collected over a period of one week, approximately one month after the fall equinox. Sky conditions varied from sunny to overcast, but 86% of all

The survey structure was composed of two sections. The first section related to both light and thermal conditions in the three different types of classrooms; the questions were adapted from the occupant questionnaire used in the IEA SHC Task21 Project [6]. Additional questions were developed to specifically probe the interactions between the user and the daylight controls and to assess qualitative impressions. The second part of the survey revolved around the environmental attributes of faculty members’ personal offices. The questions for the office environment were largely borrowed from the aforementioned Task21 Project. The questionnaire was designed to elicit occupant appraisal of the luminous environment over time.

4. FINDINGS The intent of this study is to advance the understanding of the relationship between the occupant and their daylit environment. Physical data were gathered to support user survey responses and determine daylight effectiveness, user interactions, and user satisfaction. Ultimately, the survey revealed a highly positive response to both the classrooms and the faculty offices. In response to the open-ended question “Is there anything you particularly like about this building,” 68% of individuals mentioned the natural light or daylight. Additionally, in response to

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

the question, “the overall lighting in this classroom seems...”, 83% of all respondents described the classrooms as ‘pleasant’, while 0% selected ‘undesirable’ as a descriptor. 4.1. Daylighting Effectiveness Daylighting effectiveness was first investigated through predictive modelling during the design phase to verify compliance with the LEED EQ credit 8.1 criteria. However, as previously noted, this metric inadequately addresses issues related to the quality and dynamic nature of natural light. Post occupancy field studies and user impressions provided additional insights and data to better evaluate daylight effectiveness. Findings from the field study suggest that the classrooms did indeed meet the intention of the LEED EQ credit 8.1: daylight as the primary ambient light source in 75% of areas with critical visual tasks. The perimeter classrooms revealed a fairly wide range of ambient light levels and distribution under the clear sky conditions. In the second floor classroom, electric light contributions helped to balance the daylight zone. The third floor interior classroom had relatively uniform distribution with integrated daylight and electric light. Photograph documentation of blind positions indicated that the system was responding successfully to varying daylight inputs throughout the diurnal cycle.

perceived presence of glare. The users were predominately positive or neutral in their appraisal of the effectiveness of the automated blind system. In response to the question, “how well does the automatic blind system control sunlight and glare”, 52% responded ‘excellent’ or ‘good’, while 48% responded ‘okay’ or ‘poor’. When asked for their impression of the automatic blinds 35% of respondents, for both the second and third perimeter classrooms, thought the blinds worked well in response to the sun and sky conditions, while 35% believed that sometimes they worked and sometimes they did not. 4.2. Interactive Behaviours Interactive behaviours were evaluated through occupant responses to the survey. Overall, there was a positive appraisal of the automatic blinds. Over 60% of respondents in both the second and third floor perimeter classrooms (Fig. 8) found the blind controls ‘easy to understand,’ while 25% (third perimeter) and 35% (second perimeter) of respondents thought that ‘it took a while to understand, but I do now’. Very few people found the automatic system hard to understand or frustrating. Two occupants made comments that they did not know the blind controls could be modified; this suggests a potential issue in occupant training and education of the daylighting system.

 

Figure 8: Survey – Blind control perceptions

 

  Figure 7: Survey - Glare in the classrooms

 

  There was a higher occurrence of reported glare interference on the third floor perimeter classroom (Fig. 7): 65% of faculty that taught in the second floor perimeter classroom said that glare ‘never’ or ‘only occasionally’ interfered with teaching. Alternatively, 74% of third floor respondents reported that glare from the window wall ‘often’ or ‘sometimes’ interfered with teaching. Even so, ‘sometimes’ was the most frequent answer, indicating that the daylight system is effectively mitigating glare most of the time. The discrepancies between classrooms may be attributed to the presence of the lightwell in the third floor classroom. The occupant’s impression of the effectiveness of the automatic daylight system was gauged by questions surrounding automatic blinds and the

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Figure 9: Survey – Reasons for blind overrides

Occupants were also asked to select the reasons that they chose to override blind controls by frequency (Fig.9). The most frequent responses were to darken the room for media or to brighten the room for visual comfort or preference. The third floor perimeter classroom had a higher frequency of blind control overrides in all categories; this may be

PLEA2011 - 27th International conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011 th

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

explained by the additional daylight source, the lightwell opposite of the window wall, not present on the second floor perimeter classroom. 4.3. Satisfaction Satisfaction was measured through multiple satisfaction survey questions and responses. The graph (Fig. 10) illustrates a high level of satisfaction for all types of classrooms. Mean scores were all on the positive to highly positive side of the rating scale, except for satisfaction with thermal conditions. A slight difference also existed between the two southwest facing perimeter rooms and the interior room; although the interior room responses were still on the positive side, the perimeter rooms were consistently ranked higher in satisfaction. Overall, the highest ratings were seen for the quality of light, the amount of light and satisfaction with the lighting system (both the electric and daylight systems). The mean scores for each of these categories were either equivalent to or above 1.5, on a seven point Likert scale ranging from -3 to +3, with one exception: the interior classroom was rated slightly below a +1 value for satisfaction with amount of light. Field measurements corroborate this finding, as the overall illuminance value in this classroom was much lower than those of the two perimeter rooms.

warmest space. It is unknown if the double ventilating wall was operating effectively during this period. The HVAC system was not studied as part of this research.

Figure 11: Hobo temperature readings, July

The personal office attribute satisfaction values (Fig. 12) were also very positive in appraisal, but satisfaction with thermal conditions again represented the lowest score. In fact, the majority of the written optional comments revolved around occupant issues with the thermal environment.

Figure 12: Survey – classroom temperature ratings

 

 

Figure 10: Survey – Classroom satisfaction average ratings

The lower instance of satisfaction with the thermal environment can be further explained by additional questionnaire responses, open-ended comments, and HOBO readings; 58% of individuals that taught in the second floor perimeter classroom thought the temperature was ‘about right,’ while 42% believed that the third floor interior classroom was ‘too hot’. Responses indicated that 75% of occupants agreed or noticed that the temperature ‘varied with season’ in the third floor perimeter classroom. Each classroom type revealed a wide range of responses. Additionally, 70% of respondents commented in the optional text boxes that the building was either too hot, or too cold. The HOBO field data further supports these claims revealing relatively warm temperatures across classrooms during a July time period (Fig.11). The third floor perimeter classroom was consistently the

DISCUSSION In general, this building represents an effective daylit environment-- one that responds to the variable nature of natural light and is well accepted and used by the end-user. The following points summarize the primary themes and findings: 1. A predominate theme is that there is value in a daylighting system that responds dynamically to changing light conditions while also supporting user engagement. This is demonstrated by a positive response and acceptance of the automated blinds. Significantly, a majority of the faculty regularly interacted with the daylight control system to successfully meet a variety of classroom needs and preferences. The few negative comments stemmed from a lack of understanding between the end-user and controls, suggesting that an opportunity exists for occupant education.

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PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

2. The daylight source in the interior classroom was seen as a positive environmental attribute, despite lack of views, suggesting that the addition of daylight to interior spaces is a valuable architectural strategy. 3. The thermal environment was reported as the most challenging and least positive attribute for the classrooms and offices. Dissatisfaction with thermal conditions is a common theme in post-occupancy evaluation, possibly attributed to a wide range of personal comfort factors, personal preferences and adaptation. In this case, there may be a relationship between the fully glazed double ventilated facade and thermal conditions; further study is recommended. 4. Windows and comfortable temperature were rated as the most highly valued physical attributes of personal offices. Daylight related office attributes, such as window size and view received the highest satisfaction ratings. 5. The overarching focus of this study was the occupant response to the luminous environment; as noted, the response was overall positive. Aside from observations of the daylight controls and the daylight harvesting system responding to changing climate inputs, this paper did not specifically address the energy effectiveness. This is an area for future study.

  5. CONCLUSION This study demonstrates the value of applied research to better understand emergent building trends. Future projects can leverage collected knowledge, potentially advancing innovative daylighting strategies. In this particular case, the designers were successful in viewing daylighting as a dynamic system, considering interactions between building, site, and user. Furthermore, this paper underlines the importance of the end-user perspective in providing insight to the merits, perceived value, and successes of daylit environments and related systems.

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REFERENCES [1] Edwards, L., & P. Torcellini, P. 2002. A Literature Review of the Effects of Natural Light on Building Occupants National Renewable Energy Laboratory, (NREL/TP-550-30769) Golden, CO. [2] Heschong, L, Wright, R. and S. Okura, 2002. Daylighting Impacts on Human Performance in School. Journal of the Illuminating Engineering Society, 31(2). pp.101-114. [3] Kuller, R. & C. Lindsten, 1992. Health and behaviour of children in classrooms with and without windows. Journal of Environmental Psychology, (12), pp.305-317. [4] Heerwagen, J. and L Zagreus, 2005. The Human Factors of Sustainable Building Design: Post Occupancy Evaluation of the Philip Merrill Environmental Center. Summary Report for U.S. Department of Energy, Center for the Built Environment, University of California, Berkeley, CA. [online] available at

http://www.escholarship.org/uc/item/67j1418 w#page-1 [5] Theodorson, J. 2009. Daylit Classrooms at 47N, 117W. In: PLEA 2009, Architecture Energy and the Occupant’ s Perspective: Quebec City 22-24 June, 2009. Quebec: Les Presses de l’Universite Laval. [6] Hygge, S. and H.A. Lofberg, 1999. Post occupancy evaluation of daylight in buildings. [Online] IEA SHC Task21 Project, (Published December 1999) Available at: http://www.iea-

shc.org/task21/publications/D_POE_proced ures_and_results/Task21POE.pdf [7] Reinhart, C., Mardaljevic, J., & Rogers, Z., 2006. Dynamic daylight performance metrics for sustainable building design. Leukos, 3(1), pp.731. [8] Heschong, L., 2010. Daylighting Metrics: Status and Promise. Las Vegas: LightFair 2010 Daylighting Institute. 11 May 2010.

ARCHITECTURE AND SUSTAINABLE DEVELOPMENT, Proceedings of PLEA 2011, Louvain-la-Neuve, Belgium (July 2011) ISBN th xxx-x-xxxx-xxxx-x - ISBN (USB stick) xxx-x-xxxx-xxxx-x @ Presses universitaires de Louvain 2011

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Solar Control Mechanisms: Effects on Daylight & Thermal Performance An Experimental Study on a Public Library Karl BORG1, VINCENT BUHAGIAR2 1,2

Faculty for the Built Environment, University of Malta

ABSTRACT: This study is focused on the twin-prong effects of a solar shading device in a typical Mediterranean climate, where shading from excessive solar gains needs to be well balanced by adequate daylighting. The public library at the University of Malta was considered the ideal case study for such an all-round assessment. A golden opportunity was available where the façade of the building was being retrofitted with a new innovative shading screen. The building was monitored for its temperature and humidity levels, both before and after the shading device was installed. Keywords: energy, solar control, daylighting, overheating, spectrally selective film, solar gains

1. INTRODUCTION Typically libraries are universally associated with entraining a generous amount of daylight throughout. Although highly commendable in all reading areas, it is not so ideal in Melitensiae or in the reserved collections’ area, where old or high value books tend to suffer from prolonged exposure to natural light. Reading and writing for research was the order of the day, but today we are rapidly verging towards paperless research, as we scroll the intranet across more generous databases of the same library’s internal records as well as other libraries worldwide. The computer has taken libraries by storm: it has shaken library operations and design, with quasivertical flat screens taking over the larger horizontal writing surfaces. All this implies a change in strategy in library lighting design. In spite of the state-of-the art in flat screen technology, horizontal glare from vertical or overhead surfaces is almost inevitable. Therefore there is no longer such a fixation with abundant natural light, especially as libraries are becoming larger and deeper in plan layout, demanding PSALI (Partial Supplement of Artificial Lighting). Invariably, this brings with it a greater expenditure of energy per square metre of floor space, independent of occupancy levels. This paper investigates the potential of carefully balancing adequate natural light with controlled solar gains, particularly in between reading and reference areas on a predominantly south facade at the University of Malta Library, currently (literally) experiencing a facelift. Quick fix energy saving measures include switching over form incandescent lamps or linear fluorescent neon fittings to compact fluorescent energy saving lighting, as well as the application of solar films, tinting the glass from undesirable solar gains, albeit even if all year round.

2. THE LOCAL SCENE Malta is a three Island archipelago, with a Mediterranean marine climate. A climate overview is first given. 2.1. Climate Overview

Figure 1: Percentage of total solar radiation over Malta

Malta, located at latitude 35"52'N experiences a typical Mediterranean high insolation exposure with a solar altitude at 79°C above the horizon in summer on 21 June and a winter low altitude sun at 31°C in winter on 21 December [1]. Solar radiation is very intense during the summer period especially since minimal cloud cover is experienced, if any. However in winter although the direct sunlight availability is reduced due to a higher cloud cover, a high amount of diffused radiation is present. Subsequently winter diffused light combined with a low altitude sun may be a persistent source of glare, often distracting in a working environment.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

2.2. Balanced lighting and Solar Control Although not commonly evident in most buildings, the well designed solar control system takes into consideration the need for natural light and view, and must therefore marry a number of environmental performance criteria with social, physiological and psychological requirements. [2] 2.3. Relevant Parameters In the light of the predominantly intense hot seasons, local architecture has been largely concerned with providing solar control and passive cooling. The high solar altitude during the hot seasons has given local architects a challenge to develop and incorporate simple yet effective physical solar control systems in their designs.

3. LOCAL CASE STUDY 3.1. The Need for a Face-Lift The University Library originated from within the Old University buildings in Valletta, 1954.In 1967, it was transferred to a new University Campus, Msida. The design by British firm Norman & Dawbarn [3] comprised a four-storied modular glass and concrete building with a ceramic egg-crate shading screen.

Figure 3: The intricate pattern of the egg-crate geometry gave the library’s facade a contrasting play of light and shade

The limitations of the screen manifested themselves in the deterioration of its supporting concrete frame. The concrete elements were observed to be cracking and spalling. Under architect Alex Torpiano, remedial work was carried out and the ceramic modules were dismantled and rebuilt. Although this added another 13 years to the life of the screen, further structural damage soon reappeared, putting the safety of passers-by at risk. In August 2007, Professor Torpiano informed the Malta Environment and Planning Authority (MEPA) about the situation, and MEPA later issued an emergency permit for the screen’s removal [4]. The screen gave the library building an ‘iconic’ status within the University Campus. The architectural quality of the facade combined with the prominence of its location gave the building a unique character – library and University students alike recognizing that the aesthetic value of the screen made it almost synonymous with the UoM.

Figure 2: Library building in course of construction in 1965

The use of the concrete and ceramic egg-crate screen was a much discussed issue. Those in favour saw it as an innovative way of protecting books from light and heat without creating a completely closed environment. Those against saw it as a heavyhanded external solution to a problem that could have been solved inside the building. The screen, an Islamic inspiration from the ‘Moshrabija’, was eventually decided upon. It served to reduce the cooling load by limiting solar heat gains from the persistent solar radiation. Although not an initially service, since the 1990s, the library building presently relies completely on large scale and individual HVAC systems. In spite of deploying the latest technology, they are still considered as energy guzzlers, especially in view of the long library open hours. For security reasons and dust penetration, natural ventilation was not considered an option.

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Figure 4: The prominent location of the building and its eggcrate ceramic screen gave it iconic status within UoM campus

3.2. The importance of Solar Control in a Library Following the dismantling of the screen the library building remained completely unshaded, exposing the fully glazed façades on its worst three sides, facing east, south and west. In order to limit solar heat gain and mitigate the effect of UV radiation on books, internal blinds were kept closed. Where possible, in the absence of blinds, canvas material was used to shield the interior from direct solar radiation. Heat ingress was still practically inevitable.

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Figure 5: Having become dangerous, the old ceramic screen was dismantled and removed, leaving the glazed curtain wall of the library exposed Figure 8: The particular woven metal mesh proposed as the new solar control system

Figure 6: The scenario at the Meiltensiae department threatened the books being stored there, and produced unbearable heat to staff members and students alike. A makeshift solution to limit the damage can be seen here.

Producing an exact replica of the old screen went against the principle of conservation. Furthermore, considering the system had already succumbed to its own structural defects, it would not be feasible to produce such a replica. Under the direction of architect Prof. Alex Torpiano, a temporary metal shading screen would be installed for 18 months, during which time, the possibilities of building a permanent sun-screen close to the old design will be evaluated. The new screen would be integrated into the existing façade and the spirit of the original building design will be retained – the dense mesh pattern being divided into vertical segments along the length of the façade. The mesh would be tensioned along the façade using a spring system. Steel beams will be attached to the existing concrete beams on the first and second floors, and the screen will span from the top of the façade to ground level using the beams as supports.

4. AIM OF THE STUDY

Figure 7: The absence of a solar control system forces a heavy dependance on internal blinds. As an internal shading device, the blinds mostly serve to limit glare and direct UV radiation, but have little bearing on limiting solar heat gain

MEPA approved the temporary replacement of the original screen with a woven steel sunscreen, until possibilities of other alternatives were explored. The MEPA board was initially reluctant to issue a permit and insisted on evaluating whether a replica of the old screen was possible – hence preserving the historical and architectural value of the building.

After determining the performance requirements of the solar control system at the U.O.M library, the study strived to test the proposed system using an experimental physical model setup. A number of alternative systems were earmarked, finally selecting spectrally selective glass treatment as a potential functional solution to the current situation [5]. This permitted the development of a comparative analysis, throught which the strengths, weaknesses and potential flaws of both systems could serve to give a thorough understanding of the building’s solar control strategy.

5. METHODOLOGY Physical models were used to compare the environmental performance of the woven metal mesh screen and the spectrally selective film. Two identical cells were constructed in order to create two enclosed volumes with only one variable difference between them – the glazing system. The specified solar transmittance of the mesh for a 60 degree solar altitude was used to select a spectrally selective film with similar properties. Two

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more test series included a lower performance mesh, and the same woven metal mesh mounted in a vertical orientation. The glazed fronts of the test cells were given the same orientation as that of the southfacing façade of the U.O.M. library. th th Testing took place between 15 and 30 of April 2009. The methodology was divided in the following stages in order to assess the systems on a number of selected criteria:

6. RESULTS AND PRINCIPAL FINDINGS 6.1. Stage 1: Temperature monitoring

5.1. Stage 1: Temperature monitoring The temperature inside the two cells was measured and recorded over the course of ten hours during the day. The control cell was equipped with a 4mm clear glass pane while the test cell was equipped with a similar glass pane treated with the particular solar control system being tested. Using thermocouple temperature sensors connected to a digital chart logger, temperatures were recorded at two distinct points within the cells – at the centre at mid-height, and at the centre of the internal surface of the glass pane at mid-height. The results were recorded and plotted as graphs of temperature difference against time; figures 10,11 refer. However the temperature difference between the test cell and control cell was used as the plotted value. This served to demonstrate and compare the heat rejection capacities of the two systems.

Figure 10: Graph showing averaged internal temperature differences between test and control cell, over a 10hr interval

Figure 11: Graph showing averaged glass internal surface temperature differences between test and control cell, over a 10hr interval

6.2. Stage 2: Solar Transmittance Properties Figure 9: Experimental setup of test cell (right) and control cell (left).

Table 1: (Spectrally Selective Film) 3-Day Averaged values of incident solar irradiation on the glazing system, and of transmitted irradiation within the cells.

5.2. Stage 2: Solar Transmittance Properties The solar transmittance of the solar control system was measured using a solar power meter. This measuring instrument was used to quantify the solar irradiation on the external surface of the solar control system, and again behind it. The two values were then used to compute the percentage solar transmittance of the system. 5.3. Stage 3: Visual Transmittance Properties In a method similar to the one mentioned above, a typical lux-meter was used to measure the illumination level incident on the glazing system and within the cell, to compute the visual transmittance Due to the nature of the building in question (keeping into consideration its function and the prominence of the intervention), further to the above testing, the systems were also assessed on UVperformance, their effect on view, and aesthetic considerations.

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3-Day Averaged Values 4mm Clear Glass Interior: Direct Incident Solar Radiation BTU/ ft2/hr Exterior: Direct Incident Solar Radiation BTU/ ft2/hr

4mm Clear Spectrally Film

201

Glass + Selective

38 252

% Direct Solar Transmission

= (38/252) * 100 = 15.08% (0.15)

Table 2: (Woven metal mesh) 3-Day Averaged values of incident solar irradiation on the glazing system, and of transmitted irradiation within the cells. 3-Day Averaged Values

Interior: Direct Incident Solar Radiation BTU/ ft2/hr Exterior: Direct Incident Solar Radiation BTU/ ft2/hr

4mm Clear Glass

4mm Clear Glass + Woven metal mesh

196

51 248

% Direct Solar Transmission

= (51/248) * 100 = 20.56% (0.21)

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

6.3. Stage 3: Visual Transmittance Properties Table 3: (Spectrally Selective Film) 3-Day Averaged values of incident illuminance on the exterior surface of the glazing system, and of the transmitted illuminance within the cells. 3-Day Averaged Values

Interior Direct Illuminance (in sunpatch) / Lux

4mm Clear Glass

4mm Clear Glass + Spectrally Selective film

76,600

15,070

Exterior Illuminance / Lux

87,830

% Visible Light Transmittance = (15070/87830) * 100 = 17.16% (0.17)

Table 4: (Woven Metal Mesh) 3-Day Averaged values of incident illuminance on the exterior surface of the glazing system, and of the transmitted illuminance within the cells. 3-Day Averaged Values

Interior Direct Illuminance (in sunpatch) / Lux Exterior Illuminance / Lux

4mm Clear Glass

4mm Clear Glass + Spectrally Selective film

76,100

14,270 87,100

% Visible Light Transmittance = (14270/87100) * 100 = 16.38% (0.16)

Figure 14: View through a 4mm pane of clear glass with the woven metal mesh screened over its exterior

6.5. UV Transmittance Properties As a protective measure against UV degradation of the film itself, an external coating serves to limit UV ingress to <1%. The woven metal mesh does not provide a selective filter and cannot discern between different wavelengths of the electromagnetic spectrum. Therefore the percentage UV transmittance is a function of the overall solar transmittance of the mesh – hence a function of solar altitude.[6]

7. DISCUSSION OF RESULTS 6.4. Effect on View

Figure 12: View through a 4mm pane of clear glass

Figure 13: View through a 4mm pane of clear glass with the spectrally selective film applied to its outer surface

Temperature monitoring and solar transmittance properties: From a solar control performance perspective, internal temperature build-up showed that the spectrally selective film and the woven metal mesh could markedly improve the solar rejection properties of a south facing glazing system with quasi-identical results. The actual solar transmittance value for the given experimental setup was also measured in order to quantify the actual solar properties of the two systems. Measured values of percentage solar transmittance were found to be marginally higher than those stipulated in specifications. The film exhibited a lower solar transmittance, but conversely results showed that surface temperature of the glass was higher than with the woven mesh. Finally, internal temperature patterns proved to be very similar. The essential finding was that minor performance variations could easily be attributed to solar altitude. [Basically the mesh functioned better than the film at high solar altitudes]. Although the south façade is the main potential source of heat gain, consideration of East and West façades can show how the low summer sun can be a source of significant heat gains if not properly shaded. Due to its characteristic geometrical arrangement, the solar transmittance of the mesh increases as the solar altitude decreases, hence its overall solar performance decreases on the east and west façades. The film does not exhibit any notable variations in solar transmittance with different orientations. Visual transmittance properties: The actual measured values were very close to the specified values of the products. As was the case for solar transmittance at the particualr solar altitude, the

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

visual transmittance properties of the two systems were very similar. The fine gauge of the weave still permits a decent view to the outside, but psychologically the woven metal mesh gives the effect of a secluded obstructed view, verging on a ‘caged’ feeling. Somehow this will always give the impression of a physical barrier impairing an otherwise unobstructed connection to the outside world. On the other hand the spectrally selecvtive film does not obstruct the view. However itdoes give a relatively ‘gloomy’ effect when compared to clear glass – possibly too much even on bright days, making even bright days seem dull. Psychologically this generates a feeling of gloom, affecting library users’ moods, hence their performance.

8. CONCLUSIONS Both systems are a valid solar control option for the south facing facade of the University Library building, and from an environmental performance standpoint, it can be concluded that they would give similar results. The mesh screen in reality will also serve to shade the structure, and non glazed features of the building facade, further reducing the overall heat gains of the building. Physical geometrical constraints of the woven metal mesh however, limit its viability for the east and west orientations, both requiring a solar control system. This ultimately jeopardizes the mesh screen as the singular holistic solar control system for the entire library building curtain wall. Good daylighting design of a library revolves around a multitude of parameters; in this case it was deemed important to establish the actual visual transmittance properties of the two systems in order to be able to broaden their comparative analysis. Perimeter zones enjoy the benefits of abundant daylighting. However one must consider the effects of glare in today’s studying process – commonly involving the use of vertical computer screens – albeit even with today’s anti-glare screens. UV-inhibiting properties make the spectrally selective film a more functional solution than the mesh – especially since the books are the main stockpile asset of the library. Measured in µW/lumen, UV is a function of the overall building lighting design scheme, but the library building with its fully glazed curtain wall, owes most of its UV degradation to uncontrolled natural light. Another advantage of the film lies in the fact that the view is largely unaffected, whereas with the mesh, one must consider the impact of the physical obstruction created. When considering the potential use of the spectrally selctive film, given the typology of the existing facade and the reminiscent aesthetic/iconic spirit sought [7], the overall visual effect might not be as appealing as that created by the mesh. From an architectural perspective therefore, the sole use of the film cannot be considered as a permanent solution.

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9. OVERVIEW The original aim was namely to compare the proposed solar control solution for the library with an alternative system, in terms of the performance characteristics deemed to be most prominent by the author. The various performance criteria tested/evaluated served to demonstrate the multi-disciplinary approach typically required to assess the most viable daylight/solar control system. Although in itself the methodology is by no means exhaustive, the tests themselves served to tangibly exhibit how the spectrally selective film technology could equally serve as a valid alternative to the library's proposed solar control solution. Consequentially, the study showed how the technology can be intended to serve as a minimalintervention retrofitting solution, to potentially difficult solar control problems. Finally, as the outcome, four salient features include (i) giving that much-needed respite to the building's already over-stretched mechanical cooling system – especially in light of the library’s building log, (ii)- delivering an acceptable level of visual light transmittance, (iii) retaining a good view to the exterior, (iv) eliminating UV radiation ingress in a paper-sensitive interior.

10. REFERENCES [1] Meteorological Office, Dept. of Civil Aviation, MIA - Malta International Airport, Luqa, Malta. [2] Calleja, H., (2004) Solar and Daylight Control as Applied in the Maltese Context (B.E.&A. Dissertation, University of Malta). [3] Norman & Dawbarn Architects & Town Planners, Masterplan for the New University of Malta, 1963. [4] Malta Environment & Planning Authority Planning Permission, 2007. [5] Recowatt Co. Ltd., Provider of spectrally selective film. [6] GKD – Gebr. Kufferath AG (est. 1925), a German company specializing in woven metal meshes for architectural, solar control, privacy and security applications. [7] Torpiano A.,(2009), Dean, Faculty for The Built Environment, University of Malta, (personal communication, Msida, 08 April 2009).

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Strategies for improving thermal performance and visual comfort in office buildings of Central Chile Waldo BUSTAMANTE G.1, Felipe ENCINAS2, Alan PINO3, Roberto OTAROLA3 1 2

Escuela de Arquitectura, Pontificia Universidad Católica de Chile, Santiago, Chile Architecture et Climat, Université catholique de Louvain, Louvain-la-Neuve, Belgium 3 Facultad de Ingeniería, Pontificia Universidad Católica de Chile, Santiago, Chile

ABSTRACT: Overheating, high cooling energy demand and glare are recurrent problems in office buildings in Santiago and Valparaíso, Chile. Santiago (33°S) presents a Mediterranean climate, with a high temperature oscillation between day and night during cooling period. Valparaiso (33°S), by the coast, shows lower temperature fluctuation compared with Santiago. In order to evaluate impact on thermal and lighting performance of office buildings of these cities, a sensitivity study has been made. Variations on window façade area, type of glazing, orientation, solar protection, nocturnal ventilation and respective impact on energy and lighting performance has been considered. The methodology includes an evaluation of heating and cooling demand and variation of indoor temperature when no conditioning system is applied. For this purpose a simulation software under dynamic conditions was used (TAS). The effect on natural lighting was also analysed using Radiance software. This analysis was made using Daylight Factor, Daylight Autonomy (DA) and Useful Daylight Iluminance (UDI), considering different sky conditions. Completely glazed facades, even with selective glazing are not recommended for these cities. Glare problems are possible to be avoided with appropriated solar protection, orientation of windows and selective glazing. Keywords: cooling demand, nocturnal ventilation, daylight, office buildings, visual and thermal comfort

1. INTRODUCTION In Chile, around 4.73 million of square meters of buildings of the Industry, Commerce and Financial Institutions sector were constructed during 2008 [1]. 53,2% was built in Santiago and 6,6% in Valparaíso. In Chile there is no mandatory thermal behaviour requirements for office buildings and most of their design patterns are brought from developed countries, even if some architectural strategies, such as double skin, are not suitable –for example- in Central European countries due to the generation of overheating problems, especially when they are designed with fully glazed façades [2,3]. The effect of using different strategies of architectural design and its impact on energy demand of office buildings has been extensively studied in various countries. A study in the city of London concluded that a building with effective sun protection, optimised size of windows and reduced internal gains are important to achieve energy efficiency. This cooling demand was reduced to 23% for a week with moderate temperatures and 40% for a week of extreme temperatures, compared with the same demands of the building without using the mentioned strategies. Adding night ventilation, an additional reduction of 13% was possible [4]. Given that the mentioned problems in office buildings in countries with even less severe climate than ours during summer periods and due to scarce of information available in Chile about the effect of using certain design patterns, particularly fully glazed facades in office buildings, it is important to develop quantitative studies in order to evaluate and define design strategies for comfort and energy efficiency in this type of buildings of the country.

This paper shows results of a sensitivity analysis in order to know impact on cooling and heating demand on office buildings of Valparaíso and Santiago considering different variables. These variables are: window area, solar protection, type of glazing (single, double, clear and selective) and orientation of offices. On the other hand, in order to verify lighting comfort, also day light factor and iluminance for different combinations of mentioned variables have been studied. Climate of Santiago is Mediterranean, showing high temperatures and solar radiation during spring and summer. The city is located between the coastal and the Andes Cordillera. Mean value of maximum temperature is 29,7°C and mean minimum is 13°C for the warmest month of the year (January). Mean temperature of coldest month (July) are: 3,9 °C (mean minimum) and 14,9 °C (mean maximum). A high temperature fluctuation is observed, especially in summer and intermediate seasons  Climate of Valparaiso is influenced by the Pacific Ocean, showing lower temperature oscillation than Santiago Mean value of maximum temperature is 20,8°C and mean minimum is 13,5°C for the warmest month of the year (Jan.). For the coldest month (July), mean minimum is 9,2°C and mean maximum is 14,3°C.

2. METHODOLOGY The methodology aims to study and analyze the thermal and lighting behavior of office buildings. The main objective of this work is to be able to conclude with recommendations for achieving simultaneously thermal and lighting comfort with energy efficiency. In other words, if certain strategies are recommended for achieving comfort with minimum heating and/or cooling energy demand, these strategies should also allow lighting comfort throughout the year, with

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different sky conditions. A design strategy for thermal comfort should not avoid achieving lighting comfort at the same time. 2.1. The building and thermal analysis The sensitivity analysis is developed considering a square building containing office rooms on all four orientations. This 9 story building has been specially proposed and designed for this sensitivity analysis. Figure shows a plan (16X16m) of this building.

When cooling demand was estimated, the following temperatures in the inside of each office were considered: Week days: Maximum of 26°C from 8:00 AM till 19:00 PM. Weekend days: No temperature restrictions. Infiltration rate: 0,3 ach. Ventilation rate: 1,18 ac during week days from 8:00 AM till 19:00 PM. 2.3. Methodology for the thermal analysis The methodology for thermal analysis (and for sensitivity analysis of the next point) considers the building of Figure 1, which changes on type of glazing, the presence and type of solar protection and in some cases, for cooling periods, nocturnal ventilation was assumed. Type of glazing used are: Clear single glazing clear (CS, 4mm) selective single glazing (SS, 6mm), clear double glazing (DGC) and selective double glazing (DGS). Properties of these types of glazing are shown in Table 1. LT: Light transmission, ST: Solar transmission Table 1: Properties of different types of glazing. CS

SS

DGC

DGS

LT

0,90

0,60

0,82

0,54

ST

0,82

0,50

0,68

0,41

U (W/m2°C)

5,80

5,70

2,78

2,76

 

Figure 1: Plan of the building with the selected spaces and their orientations

Specifications of the original building are:

 

Reinforced concrete 150mm with external EPS 30mm. U=1,0 W/m2°C Roof: Reinforced concrete 150mm with EPS 60mm. 2 U=0,59W/m °C (in Valparaíso) and with 80 mm of EPS in Santiago. U= 0,40 W/m2°C. 2 Windows: single glazing, clear. U=5,8 W/m °C, Lighting transmittance: 0,90 Solar transmittance: 0,87. In case of windows, this corresponds to the initial situation. Later, this type of glazing is changed during the sensibility process. It is necessary to mention that it is still common to find new office buildings with single glazing in the country. Heating and cooling demand for different specifications of the building were estimated with TAS, software under dynamic conditions. Different ventilation rates may also be applied using this software, which permits to evaluate impact of nocturnal ventilation. 2.2. Internal gains and internal conditions Internal gains of the buildings considered are the following: 2 People: 9,38 W/m (sensible) 6,88 W/m2 (latent). Lighting: 11 W/m2. Equipment: 11,25 W/m2.

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Type of solar protections that have been used are: Horizontal blinds (HB) and overhangs (OH). Nocturnal ventilation has been applied on cooling periods of the year with 8,0 ach from 23:00 till 7:00 AM of the next day, from Sunday night till Friday in the morning. Finally, 3 different window sizes (window to façade ratio) were also applied. Cooling and heating energy demand was estimated (with TAS). Also, for each zone of a certain floor of the building, these energy demands were also estimated for offices with different orientations (N, NW, NE, W, E, SW, S, SE. See Figure 1).

 

2.4. Methodology for the sensitivity analysis The seminal study of Hamby (1991) indicates that sensibility analysis may be conducted for a number of reasons including the need to determine: (1) which parameters require additional research in order to reduce the uncertainty of the input model, that is, the building performance; (2) which parameters are insignificant and can be eliminated from the final model; (3) which inputs contribute most to output variability; and (4) which parameters are most highly correlated with the output [5]. Besides sensitivities – that can be defined as the level of influence on the output model – the importance of the variables can be assessed. The term ‘importance’ is used here in the sense described by De Wit (2002), which expresses the relative contribution of a certain variable to the uncertainty, in the model output [6].

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Between all the initially described aspects, (3) and (4) appears closely related since according to the same author, an important parameter is always sensitive because parameter variability will not appear in the output unless the model is sensitive to the input [5]. In this context, a factorial design involves a given number of samples per each input parameter and consequently running the model for all combination of samples [5]. This method is based on the sampling-based approach, where the model is repeatedly executed from the combination of input parameters sampled with some probability distribution. Since the design of this sensibility analysis consists in 4 input parameters with 3, 3, 4 and 8 parameters per each one, the total combination of samples gives a complete sample of 288 cases. Each case has an equal probability of occurrence corresponding to 1/N (0,35%, where N=288) due to a uniform probability density function was applied to each input parameter. Table 1 presents the different input parameters considered for this study and their associated variables.

    35,0   30,0   25,0   20,0   15,0   10,0  5,0  0,0    

T° ºC

Glazing ratio*

Types of solar protection devices

3

3

Types of glazing

4

Orientations

8

Description of variables 20% 50% 100% Without solar protection Overhang in N orientation and blinds for E and W orientations Blinds in N, E and W orientations Single glazing, clear Single glazing, selective Double glazing, clear Double glazing, selective All orientations (N, NE, E, SE, S, SW, W, NW)

(*) Ratio of the glazed area with respect to the total area of the exposed envelope

3. RESULTS 3.1. Thermal analysis Respecting to temperature variation, as expected, overheating is observed in offices of northern, west and east orientation. When having 100% glazed buildings, even in Santiago and Valparaíso, overheating (or a high cooling energy demand) does surely exist in a summer day. Under clear sky conditions, even in winter days, overheating is also possible to be reached. Figure 2 shows temperature variation in zones N of the building (according to Figure 1), when the building is completely glazed, with and without solar protection (which is supposed to be designed for cooling periods). Temperature is little higher when considering selective double glazing (DGS), respective to clear double glazing (DGC) with solar protection in this northern office room.

Global solar radiation 1200 1000 800 600 400

Solar Rad, W/m2

200 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hours

Figure 2: Temperature variation in Zones N of the building for a winter day in Valparaíso. 100% glazed façade. Winter day

Figure 3 shows that identical problems are also observed in the case of Santiago, applying a completely glazed façade during a winter day under clear sky condition.

Table 2: Input parameters for sensibility analysis Number of variables

Zone N DGS

Zone N  DGC + solar protection

40,0

 

Input parameters

External Temperature

External Temperature

Zone  N DGS

Zone N  DGC + solar protection

Global solar radiation 1200

40 35

1000

30

800

25 T 20 ºC 15

600 400

10

Solar  Rad. W/m2

200

5 0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour

Figure 3: Temperature variation in Zones N of the building for a winter day in Santiago. 100% glazed façade. Winter day.

As observed, 100% façade ratio is not recommended for both cities considered in this study due to overheating generated even in some clear sky winter days. If the phenomenon occurs during winter time, it is expected to have it during summer. In the city of Santiago, overheating is also observed with 20% of glazing ratio (clear or selective double glazing), especially when no solar protection is used. In this case, temperatures higher than 32°C are reached in western offices of the building. The problem is less intensive in Valparaíso. Respecting to office energy demand, as expected, cooling is significantly higher than heating in both cities. Table 2 shows cooling energy demand for the 6th floor of the building when using different glazing ratio on façade (considering double glazing selective). In all cases solar protection is applied, (blinds for east and west facades and overhangs for northern façades). On the right column, the cooling demand corresponds to situation when nocturnal ventilation is used. Comparing these values with those of the left column, it is observed that this strategy is highly

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

effective in the city of Santiago (especially when combined with high thermal inertia due to use of external insulation). On the other hand, the lower cooling demand is reached when minimizing the glazing ratio. Table 2.: Building cooling demand in Santiago Glazing ratio

kWh/m2 y

kWh/m2 y

20%

20.2

9.9

50%

37.2

30.6

100%

62.9

47.2

In all cases showed in Table 2, heating demand is low, reaching 4,6 kWh/m2 y in the case of 20% of glazing and only 1,6 kWh/m2 y, in the case of a completely glazed façade. In the case of Valparaíso, the lower cooling demand on floor 6 of the building was reached when considering 20% of selective double glazing, with a cooling demand of 14.6 kWh/m2 y and a heating demand of 3.7 kWh/m2 y. 3.2. Sensibility analysis

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∑�������� � � � ���� � � �

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�∑�������� � � � ��� ∑������� � � ����   for the correlation between Xi and Y. The larger the absolute value of r, the stronger the degree of linear relationship between the input and output values. At the same time, a negative value of r indicates that the output is inversely (or negatively) related to the input. Table 3 presents the correlation coefficients for the different input parameters with respect to the cooling demand in the case of Valparaiso. According to this, glazing ration appears clearly as the most sensitive parameter, secondly ranked by the types of solar protection devices (which is negatively correlated) and finally by the types of glazing. On the contrary, orientation does not appear with a statistically significant correlation (at the 0.01 or 0.05 level). This result is highly consistent with the one-at-atime sensitive analysis of the Figures 4 and 5, where the uncertainty of the glazing ratio and orientation, respectively, is propagated on the assessment results. Figure 4 shows as the high level of importance of glazing ratio, since the variability in output – as consequence of the input variability – is

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Table 3: Pearson’s correlation coefficient for the different input parameters with respect to the cooling demand in the case of Valparaiso Pearson’s r Glazing ratio 0.73 Types of solar protection devices -0.25 Types of glazing 0.12 Orientation 0.10 Correlation is significant at the 0.01 level (2 tailed) Correlation is significant at the 0.05 level (2 tailed)

   

100%

One of the most applied methods for parameter sensitivity analysis that use sampling techniques is the Pearson’s product moment correlation coefficient [7]. This method appears as appropriate since parameter sensitivity depends not only on the range and distribution of an individual parameter, but also on those of other parameters to which the model is sensitive [5]. Pearson’s correlation coefficient represents the quantitative estimation of the linear correlation for parameters values of input and output. This indicator is denoted by r and is defined as:

 

noticeable. On the contrary, Figure 5 shows as the variability of the output results per orientation is reduced, which is even more critical with regard to the range of low cooling demands. At the light of these results, it is clear that any design strategy proposed for new office developments in Valparaiso, should prioritize the ration of the glazed area with respect to the exposed façade. Very similar results were observer also in the case of Santiago.

    80%     60%       40%     20%     0%   10  

20% 50% 100% 30

50

70

90

110 130 150 170 190

Cooling demand [kWh/m²/y] Figure 4: Cumulative frequency for cooling demand with respect to glazing ratio in the case of Valparaiso. 100% 80%  

 

N NE E SE S SW W NW

  60%

    40%     20%     0%   10  

30

50 70 90 110 130 150 170 190 Cooling demand [kWh/m²/y]

Figure 5: Cumulative frequency for cooling demand with respect to orientations in the case of Valparaiso

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

3.3. Daylight analysis Figures 6 and 7 present the results of the daylight analysis in terms of daylight autonomy (DA) and useful daylight illuminance (UDI) for the range over 2000 lux for the case of Santiago. DA uses work plane illuminance as an indicator of whether there is sufficient daylight in a space so that an occupant can work by daylight alone [8]. In this case, the required minimum illuminance level was defined for a basis of 500 lux according to the recommendations of IESNA [9]. UDI constitutes other important dynamic daylight metric. This indicator is dynamic daylight performance measure illuminances, which uses hourly climate-data (mainly direct and diffuse radiation and cloudiness) for a specific location and based also on a work plane. The advantage of this condition – in comparison to static metrics – is that the UDI considers the quantity and character of daily and seasonal variations of daylight for a given building site [8]. 100% 80%  

 

60%  

      20%     0% 40%

N

E

S

W

Without solar protection With blinds in N, E and W orientations Note:  The centre point of each bubble is the extent of overeating measured in percent (mean value for the different points across the space). The area of the bubble represents the standard deviation for the distribution of values including the same points. Figure 6: Bubble plots for daylight autonomy (DA) based on a required illuminance level of 500 lux in different orientations in Santiago 100%

    80%     60%     40%     20%   0%  

N

E

S

W

Without solar protection With blinds in N, E and W orientations Figure 7: Bubble plots for UDI in the range over 2000 lux for different orientations in Santiago

As it name suggest, the aim of UDI is to determine when daylight levels are useful for the user, in this cases neither too dark (less than 100 lux) nor too bright (over 2000 lux). This range is proposed by Nabil & Mardaljevic (2006) based on occupant preferences in naturally illuminated offices [8]. Based on the upper thresholds of 2000 lux, the resultant UDI metric was applied to this research, which may suggest the presence of glare. At the same time, daylight autonomy was applied for a level of 500 lux. Both of them were assessed over a grid of 36 points (6 rows x 6 columns) at 1.0 m height in the study case office already represented in Figure 1. Figures 6 and 7 show the impact of incorporating horizontal blinds in north, east and west orientations in terms of the useful illuminance. The percentage of UDI over 2000 lux is clearly lower when these devices are considered. However, as the area of each bubble represents the standard deviation, the dispersion of values may be higher. At the same time, DA shows that it is possible to guarantee an adequate minimum level of illuminance even with the use of blinds. These results suggest, for example, that the incorporation of lightshelves (in combination with blinds) may contribute to reach a most homogenous illuminances inside the room, without jeopardize the favorable mean values. However, this hypothesis constitutes a new aspect of the research that it should be tested by means of a series of new simulations. Consequently, the use of lightshelves in the context of office buildings in Santiago is proposed as further research.

4. CONCLUSIONS First of all, completely glazed façade office buildings are not recommended for cities of Santiago and Valparaiso, Chile. In both cities, with different climates, the best thermal performance (regarding cooling energy demand) is reached with the lower the window ratio (20%), especially when considering solar protection on glazed areas, which is highly recommended – in order to avoid overheating - for north, east and west orientations. At the same time, with respect to the visual comfort, the incorporation of blinds permit to suggest that glare problems at least may be reduced or even avoided. It was also observed that in the case of Valparaiso, higher attention to window area than to orientation of the building should be taken into account. In the case of Santiago due to high temperature fluctuation during cooling period of the year and use of thermal inertia, nocturnal ventilation has been shown to be highly effective for reducing cooling demand. When considering this strategy, combined with a low window ratio (20%, double glazing selective) and effective solar protection, cooling demand decreases in an 84% respective to a completely glazed office building, with identical type of glazing and solar protection.

 

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This research permitted to conclude that it may be possible to reach thermal and visual comfort with energy efficiency in office buildings of Santiago and Valparaiso.

5. ACKNOWLEDGEMENTS This research has been carried out as part of the project FONDECYT N° 1090602 funded by CONICYT, Chile.

6. REFERENCES [1] INE 2008. Anuario de Edificación 2008. Instituto Nacional de Estadísticas Santiago. Chile. [2] Manz, H. and Th. Frank 2005. Thermal simulation of buildings with double-skin façades. Energy and Building, 37: p. 1114-1121. [3] Gratia, E. and A. De Herde 2007. Are energy consumption decreased with the addition of a double skin? Energy and Building 39 : p. 605619. [4] Kolokotroni, G.I.&Watkins R. 2006. The effect of London heat island summer cooling demanda and night ventilation strategies. Solar Energy, N°80, pp.383-392. [5] Hamby, DM 1994, ‘A review of techniques for parameter sensitivity analysis of environmental models’, Environmental Monitoring and Assessment, no. 32, pp. 135-154. [6] De Wit, S & Augenbroe, G 2002, ‘Analysis of uncertainty in building design evaluations and its implications’, Energy and Buildings, no. 34, pp. 951-958. [7] Hopfe, C, Hensen, J & Plokker, W 2006, ‘Introducing uncertainty and sensitivity analysis in non-modifiable building performance software’ Proceedings of the 1st IBPSA Germany/Austria Conference BauSIM, International Building Performance Simulation Association, Munich, 911 October. [8] Reinhart, C, Mardaljevic, J, & Rogers, Z 2006, Dynamic daylight performance metrics for sustainable building design, National Research Council Canada, http://www.nrccnrc.gc.ca/obj/irc/doc/pubs/nrcc48669/nrcc4866 9.pdf [9] IESNA 2000, The IESNA Lighting Handbook. Reference & Application (Ninth Edition ed.). (M. S. Rea, Ed.) New York, United States of America: Illuminating Engineering Society of North America.

           

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PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011.

Author Index Abreu Loyde Vieira de .............................. T1-245 Acha Consuelo.......................................... T2-267 Acha Román Consuelo............................. T1-279 Adhikari Rajendra S.................................. T2-515 ..................................................................T2-577 Adolphe Luc..............................................T1-375 Agnoli Stefano........................................... T1-357 Aguirre Nunez Carlos................................ T2-23 ..................................................................T2-125 Aguliar Alexis............................................. T2-59 Akbar Taghvaee Ali.................................... T2-291 Alders Noortje............................................ T1-601 Aleixo Joana.............................................. T2-38 Alonso Javier............................................. T1-685 Alonso Carlos............................................ T2-59 Alpuche Maria Guadalupe......................... T1-571 Altan Hasim...............................................T1-52 Altomonte Sergio....................................... T1-83 Alucci Marcia Peinado............................... T1-433 Álvarez Dominguez Servando................... T2-23 An Xipo......................................................T1-227 Anand Isha................................................T1-867 Andersen Marilyne.................................... T1-783 ..................................................................T1-795 ..................................................................T1-801 Andrade L. M. S........................................ T1-95 Anees Mohamed....................................... T1-807 Arafa Rasha..............................................T1-807 Arrieta Marta ............................................. T2-441 Asawa Takashi........................................... T1-273 ..................................................................T2-29 ..................................................................T2-565 Asmussen Thorbjørn Færing..................... T1-615 Athway Abigail........................................... T1-183 Attia Shady................................................T2-77 ..................................................................T2-205 ..................................................................T2-459 Avesani Stefano........................................ T2-83 Azarbayjani Mona..................................... T2-533 Baeli Marion..............................................T2-613 Balocco Carla............................................ T1-789 Bansal Nitin...............................................T2-309 Barde Saurabh.......................................... T1-861 Barlet Aline................................................T1-421 Barros R. R. M. P....................................... T1-95 Bastos Jorge............................................ T2-193 Beaumont Jacques.................................... T1-421 Beckers Benoit.......................................... T2-395 Bedir Merve...............................................T1-469 Bedoya Frutos César................................ T1-107 ..................................................................T1-279 ..................................................................T1-685 ..................................................................T2-229 Ben Avraham Oren ................................... T2-107 Beneyto-Ferre Jordi................................... T1-319 Besser Jelves Daniela............................... T1-157 ..................................................................T2-471 Biesbroeck K............................................. T2-279 Bignon Jean-Claude.................................. T1-257 Blanco-Lion Cristina.................................. T2-435 Blumsack Seth.......................................... T1-621 Bodart Magali............................................ T1-777

..................................................................T1-819 Bogo Amilcar J.......................................... T1-837 Bohnenberger Sascha............................... T1-319 Bojórquez-Morales Gonzalo...................... T1-547 Boland Philippe......................................... T2-187 Bonneaud Frédéric.................................... T1-375 Borg Karl...................................................T1-897 Bothwell Keith............................................ T2-589 Boualem Ouazia........................................ T2-425 Boughlagem Dino...................................... T1-65 Braz Susana..............................................T2-389 Breesch Hilde............................................ T1-751 ..................................................................T2-279 Broers Wendy............................................ T1-45 Bueno-Bartholomei Carolina Lotuffo......... T1-415 Buhagiar Vincent....................................... T1-897 ..................................................................T2-651 Bustamante Gomez Waldo........................ T1-903 Caamaño Estefania................................... T1-107 Cadoni Gianluca........................................ T1-659 Caldieron Jean-Martin............................... T1-427 ..................................................................T1-595 Cameron Ellen........................................... T1-565 Campbell James W. P................................ T1-757 Campo Elena............................................. T2-441 Canbolat Tülay (Özdemir)......................... T2-489 Canton María Alicia................................... T2-477 Capeluto Isaac Guedi................................ T1-879 ..................................................................T2-107 Cardoso Ana Gabriela S.A........................ T1-673 Carfrae Jim................................................T2-255 Carneiro Claudio....................................... T1-789 Carnielo Emiliano...................................... T1-357 Carter David..............................................T1-831 Castorena Gloria....................................... T2-507 Castro Luíza C.......................................... T1-119 Cauwerts Coralie....................................... T1-819 Celis Mercier Silvestre............................... T2-425 Cerón Isabel..............................................T1-345 Cevada Caroline........................................ T2-407 Chanampa Mariana................................... T1-279 Chen Yanti.................................................T1-157 Chen Ruei-Ling......................................... T1-269 Chisholm Sophie....................................... T1-33 ..................................................................T2-181 Claro Anderson.......................................... T1-837 Clette Véronique........................................ T1-293 Cocci Grifoni Roberta................................ T1-397 Coch Roura Helena................................... T2-59 ..................................................................T2-235 Conto Olga................................................T1-565 Cormier Chaim Giselle Marie.................... T2-145 Cornelis An................................................T2-541 Corral Maria...............................................T2-363 Correia Guedes Manuel............................ T2-381 Costa Angelina.......................................... T2-407 Craddock Nigel.......................................... T2-133 Cre Johan..................................................T2-601 Curreli Alessandra..................................... T2-235 Czajkowski Jorge...................................... T2-583 Dacanal Cristiane...................................... T1-195 ..................................................................T1-415

909

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. ..................................................................T1-553 Daems Amélie........................................... T1-293 Daly Patrick...............................................T1-369 ..................................................................T2-369 Dave Shreya..............................................T1-801 Dawance Thomas...................................... T1-293 Day Julia....................................................T1-891 De Bondt Kevin......................................... T1-263 De Flander Katleen................................... T1-45 De Herde André......................................... T2-77 ..................................................................T2-205 De La Peña González Ana María.............. T2-345 de Meester Tatiana.................................... T1-451 De Meester Bram...................................... T1-751 De Myttenaere Kristel................................ T1-21 ..................................................................T2-553 De Siqueira Gustavo................................. T1-583 De Wilde Pieter......................................... T1-529 ..................................................................T2-139 Delas Julien............................................... T1-421 Deligne Chloé............................................ T1-263 Deshpande Jayashree.............................. T1-297 Desthieux Gilles........................................ T1-789 Deveci Gokay............................................T2-261 Dewilde Pieter........................................... T2-255 Dijkmans Tim.............................................T2-547 Dobbert Léa Y............................................ T1-553 Domin Christopher.................................... T1-631 Drakou Aikaterini....................................... T1-475 ..................................................................T1-583 Drogemuller Robin.................................... T2-47 Drori Daphna............................................. T1-177 Dry Maria...................................................T2-595 Du Jiangtao...............................................T1-765 ..................................................................T1-813 Duchhart Ingrid.......................................... T2-459 Duer Karsten.............................................T1-615 Durga Giridhar Jyothsna........................... T1-873 Edelman Marja.......................................... T2-175 Elsharkawy Heba...................................... T1-313 El-Zafarany Abbas..................................... T1-807 Encinas Pino Felipe................................... T1-541 ..................................................................T1-903 ..................................................................T2-23 Ernest Raha..............................................T2-303 Espinoza José Antonio.............................. T2-321 Esposito Fulvio.......................................... T2-223 Exner Dagmar........................................... T2-83 Farias Macarena....................................... T2-441 Farias Dos Santos Myrthes Marcele......... T1-169 Fedrizzi Beatriz.......................................... T1-727 Feifer Lone................................................T1-133 Fernández Holloway Daniela.................... T1-327 Fernandez Llano Jorge ............................ T2-477 Figueroa Aníbal......................................... T2-507 Finocchiaro Luca....................................... T1-511 Foglia Luigi................................................T2-151 Foldbjerg Peter.......................................... T1-615 Fonseca Raphaela W................................ T1-119 Foradini Flavio........................................... T2-175 Ford Brian..................................................T1-157 ..................................................................T1-745 ..................................................................T2-495 Frazer John...............................................T2-47 Frontini Francesco..................................... T1-771

910

Fuentes Víctor........................................... T2-507 Gagliano Antonio....................................... T1-639 Gagne Jaime M. L..................................... T1-795 Galesi Aldo................................................T1-639 Ganem Carolina........................................ T2-477 Garcia Chávez José Roberto.................... T2-273 ..................................................................T2-507 García-Cueto Rafael................................. T1-547 Garcia-Santos Alfonso............................... T1-107 Gbedji Flora...............................................T1-421 Gentry Thomas A....................................... T1-125 ..................................................................T1-665 Georges Laurent....................................... T1-609 Geurts Chris.............................................. T2-547 Ghisi Enedir...............................................T1-673 Gibson Andrew.......................................... T1-83 Gillot Mark.................................................T1-493 Givoni Baruch............................................ T2-273 Gomez Adolfo............................................ T1-46 Gómez Analía Fernanda........................... T2-583 Gómez González Alberto.......................... T1-279 Gómez-Azpeitia Gabriel............................ T1-54 ..................................................................T1-463 Gommans Leo........................................... T1-45 Gonçalves Hélder...................................... T1-645 ..................................................................T2-193 Gonçalves Joana Carla S.......................... T2-375 ..................................................................T2-447 Gonzales Jose Carlos............................... T1-351 Gori Virginia...............................................T1-789 Grandjean Martin....................................... T1-293 Greenan Rory............................................ T2-559 Gregg Matthew.......................................... T1-233 Grigoletti Giane......................................... T1-703 Grondzik Walter......................................... T1-71 Guedes Manuel Correia............................ T2-389 Guerra Raquel........................................... T2-229 Gupta Rajat............................................... T1-233 Gürani Fehime Yeşim................................ T2-489 Gurgel de Castro Fontes Maria Solange... T1-415 Gwilliam Julie............................................ T1-151 Gylling Gitte............................................... T2-11 Haefeli Peter..............................................T2-625 Haglund Bruce........................................... T1-71 Haksar Rohan R........................................ T1-621 Ham Michiel...............................................T2-547 Hamada Luciana....................................... T1-169 Hamza Neveen.......................................... T1-39 Han Chien-Yuan........................................ T1-843 Hancock Mary........................................... T2-17 Hanin Yves................................................T1-293 Hansen Ellen K.......................................... T2-11 Hasselaar Evert......................................... T1-469 Heiselberg Per K....................................... T2-11 Henreique Rangel Costa George.............. T1-301 Hernández-Martinez M. Carolina.............. T1-107 ..................................................................T1-345 Herrera Luis Carlos................................... T1-463 Hestnes Anne Grete.................................. T1-511 Hilderson Wouter....................................... T2-601 Horne Ralph.............................................. T2-101 Hoyano Akira.............................................T1-273 ..................................................................T2-29 ..................................................................T2-113 ..................................................................T2-465

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. ..................................................................T2-565 Hu Jianxin..................................................T1-813 Huang Kuo-Tsang...................................... T1-559 Humel Lafratta Fernando.......................... T1-301 Hwang Ruey-Lung..................................... T1-269 ..................................................................T1-843 Hyde Richard............................................. T2-607 Ignatius Marcel.......................................... T1-239 ..................................................................T1-445 Ilia Polytimi................................................T1-885 Indraganti Madhavi.................................... T1-505 ..................................................................T2-413 Irger Matthias............................................ T1-285 Itard Laure.................................................T1-469 Iulo Lisa D.................................................T1-621 ..................................................................T2-247 Iyer-Raniga Usha...................................... T2-101 Jenkins Huw..............................................T2-637 Jinghua Liu................................................T2-339 Jobard Nicolas........................................... T2-297 Johansson Erik.......................................... T1-577 ..................................................................T1-589 Jones Laura...............................................T1-529 Jones Phil..................................................T2-637 ..................................................................T2-651 Jonkers Job...............................................T2-54 Jowett Owen.............................................. T1-339 Jusuf Steve Kardinal................................. T1-219 ..................................................................T1-239 ..................................................................T1-445 Kafassis Natalia......................................... T1-481 Kaimakliotis Dimitris.................................. T1-855 Kalisperis Loukas...................................... T2-527 Kanters Jouri.............................................T2-65 Karlapudy Devasahayam.......................... T2-413 Karthaus Roland........................................ T1-145 Kates Joshua.............................................T1-487 Kawai Hidenori.......................................... T2-565 Keeffe Greg...............................................T1-721 Keonil Nuchnapang................................... T2-211 Kimpian Judit............................................. T1-33 ..................................................................T2-181 Klein Ralf...................................................T1-751 Knudstrup Mary-Ann................................. T2-11 Ko Joy.......................................................T2-53 Kondratenko Irena..................................... T2-601 Konstantina Saranti................................... T2-419 Kowaltowski Doris C. C. K......................... T2-169 Kubota Tetsu.............................................. T1-457 Kumakura Eiko.......................................... T2-113 Kurvers Stanley......................................... T1-601 Kwok Alison...............................................T1-71 Kyrkou Dimitra........................................... T1-145 Labaki Lucila Chebel................................. T1-189 ..................................................................T1-195 ..................................................................T1-245 ..................................................................T1-415 Lannon Simon........................................... T2-637 Latini Giovanni........................................... T1-397 Lau Ka Lun................................................T1-213 Lau Benson...............................................T1-387 ..................................................................T1-849 ..................................................................T1-855 ..................................................................T1-861 ..................................................................T1-873

..................................................................T2-471 Leme Neusa..............................................T2-407 Lenzholzer Sanda..................................... T1-403 Liang Han-Hsi............................................ T1-269 ..................................................................T1-559 Lichtenberg Jos......................................... T2-547 Lima Eliane................................................T2-441 Lin Chuang-Hung...................................... T1-559 ..................................................................T1-843 Lin Cheng..................................................T2-339 Lisboa Marcio............................................ T1-301 Liu Ning.....................................................T2-297 Liu Margaret..............................................T2-607 Lollini Roberto........................................... T2-83 Longo Elena.............................................. T2-515 ..................................................................T2-577 López Cristina........................................... T2-441 Lopez De Asiain Maria.............................. T1-101 Lopez De Asiain Jaime.............................. T1-101 Lucchi Elena.............................................. T2-571 Luna-León Aníbal...................................... T1-547 ..................................................................T2-363 Lytra Viktoria.............................................. T1-825 Ma Jie........................................................T2-315 Ma Maggie Mei Ki...................................... T2-453 Mahaut Valérie........................................... T1-263 Mainwaring David E.................................. T1-319 Makrodimitri Magdalini.............................. T1-757 Malekzadeh Masoud................................. T1-65 Mallion Paul............................................... T2-589 Mandalaki M..............................................T1-627 Mangone Giancarlo................................... T1-427 ..................................................................T1-595 Marina Michailidou.................................... T1-439 Marincic Irene............................................ T1-571 Marique Anne-Françoise........................... T1-27 ..................................................................T1-451 ..................................................................T2-119 Marmolejo Duarte Carlos.......................... T2-125 Marsh Phillipa............................................ T1-691 Martin Craig Lee........................................ T1-363 ..................................................................T2-401 Massart Catherine..................................... T1-609 ..................................................................T2-217 Mayhoub Mohammed................................ T1-831 Medlin Larry...............................................T1-631 Meizoso Maria........................................... T1-351 Melero Sofía.............................................. T2-267 Mena-Deferme Maria................................ T1-59 Méquignon Marc........................................ T1-375 Mestre Nieves........................................... T2-431 Miana Anna C............................................ T2-375 Mills Gerald...............................................T1-409 Mirthes Hackenberg Ana........................... T1-301 Mlecnik Erwin............................................ T2-601 Mohanty Pattnaik Ompriya........................ T2-495 Monfared Ida G......................................... T1-535 Monteiro Leonardo Marques..................... T1-433 ..................................................................T2-375 Montejo Carmen........................................ T1-345 Morello Eugenio........................................ T1-789 Morgado Baca Inmaculada....................... T1-279 ..................................................................T2-267 Motalaei Ajmeh.......................................... T2-291 Moura Norberto C..................................... T2-375

911

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. Mu Jun.......................................................T2-315 Mulfarth Roberta C. K............................... T2-375 Muller Sâmila............................................. T1-703 Munari Probst MariaCristina..................... T2-175 Murakami Edson....................................... T1-301 Murakami Akinobu..................................... T2-465 Murphy Mark.............................................T1-511 Musau Filbert.............................................T2-261 Nakamura Ben.......................................... T2-565 Nakamura Miwako..................................... T2-565 Nakaohkubo Kazuaki................................ T2-113 Neila González Javier............................... T1-107 ..................................................................T1-279 ..................................................................T1-345 ..................................................................T1-685 ..................................................................T1-733 ..................................................................T2-229 ..................................................................T2-267 Nemeth Robert.......................................... T2-533 Ng Edward.................................................T1-213 ..................................................................T1-227 ..................................................................T2-315 Ní Hógáin Sadhbh..................................... T2-631 Nikolopoulou Marialena............................. T1-415 Nocera Francesco..................................... T1-639 Norambuena Tomas.................................. T1-777 Norford Leslie K......................................... T1-795 Ochoa José Manuel.................................. T1-571 Oliveira Mariela......................................... T1-189 Oliveira Panão Marta................................. T1-645 Olivieri Francesca...................................... T1-685 ..................................................................T1-733 ..................................................................T2-229 Otarola Roberto......................................... T1-903 Otis Tiffany.................................................T1-77 Pan Wei....................................................T2-139 Paoletti Giulia............................................ T2-83 Papamanolis Nikos.................................... T1-627 Patania Francesco.................................... T1-639 Patil Arti.....................................................T1-381 Pelsmakers Sofie...................................... T1-145 ..................................................................T2-89 ..................................................................T2-435 ..................................................................T2-613 Peña Leticia..............................................T2-333 Pereira Fernando O. R.............................. T1-119 ..................................................................T1-837 Pereira Alice C........................................... T1-119 Pereira Italma............................................T2-381 Peretti Giulia..............................................T2-285 Perez Del Real Pilar.................................. T1-101 Perriccioli Massimo.................................... T2-501 Pesquale Lisa Ann..................................... T2-17 Peters Terri................................................T2-655 Pettinari Sonia........................................... T2-501 Philokyprou Maria...................................... T1-89 Piderit Beatriz............................................T1-777 Pilling Matthew.......................................... T2-401 Pino Alan...................................................T1-903 Pires Fernando C..................................... T1-119 Pitts Adrian................................................T2-645 Place Wayne.............................................T1-813 Poerschke Ute........................................... T2-527 Polakit Kasama......................................... T1-427 ..................................................................T1-595

912

Potvin André.............................................. T2-425 Pracchi Valeria........................................... T2-515 ..................................................................T2-577 Prata Alessandra R................................... T2-375 Quigley Bruce L......................................... T2-247 Radhi Hassan............................................ T1-251 Rafiq Yaqub...............................................T2-139 Rakha Tarek..............................................T1-807 Ramirez Li Ramón..................................... T2-345 Ranjbar Ehsan........................................... T2-291 Regnault Cécile......................................... T1-421 Reiter Sigrid...............................................T1-27 ..................................................................T1-451 ..................................................................T2-119 Reja Yousuf...............................................T1-201 Ren Chao..................................................T1-213 Reyes Javier..............................................T2-327 Reza Pourjafar Mohammad...................... T2-291 Rodrigues Lucelia...................................... T1-493 ..................................................................T2-471 Rodrigues Fernanda.................................. T2-199 Rodrigues Raissa...................................... T2-407 Rodriguez Jorge........................................ T1-59 Roecker Christian...................................... T2-17 Roels Staf..................................................T1-679 Roetzel Astrid............................................ T1-475 ..................................................................T1-583 Rogora Alessandro.................................... T2-515 ..................................................................T2-577 Romero Ramona....................................... T2-363 Rosina Elisabetta...................................... T2-515 ..................................................................T2-577 Rossi Monica............................................. T2-501 Rotta Renata.............................................T1-703 Rousseaux Véronique............................... T1-293 Rovers Ronald........................................... T1-45 Ruiz-Torres Pavel...................................... T1-463 ..................................................................T1-547 Rutherford Peter........................................ T1-83 ..................................................................T1-313 Sá Maria João........................................... T2-199 Saadon Nurul Ain...................................... T1-499 Sabhaney Rudrajit..................................... T2-95 Sabry Hanan.............................................T1-807 Saelens Dirk..............................................T1-679 Sahachaisaeree Nopadon......................... T2-211 Saich Mark................................................T2-589 Sakarellou-Tousi Natalia............................ T1-849 Salim Flora................................................T2-47 Salman Tugba........................................... T2-89 Salvalai Graziano...................................... T2-223 Salvetti María Belén.................................. T2-583 Samsudin Rosita....................................... T1-239 Sanchez De La Flor Francisco José......... T2-23 Sandoval Lidia........................................... T2-333 Santamouris Mattheos.............................. T2-527 Santos Joel................................................T2-407 Saranti Konstantina................................... T1-565 Sato Rihito.................................................T2-29 ..................................................................T2-565 Sattler Miguel Aloysio................................ T1-95 ..................................................................T1-727 Savioli Deliberador Marcella...................... T2-169 Schippa Giulia........................................... T2-515 ..................................................................T2-577

PLEA 2011 - 27th Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. Schuster Heide.......................................... T2-285 Sekar Dineshkumar................................... T1-873 Semidor Catherine.................................... T1-421 Serra Rafael..............................................T2-59 Sesana Marta Maria.................................. T2-223 Shajahan Amreen...................................... T1-201 Sharples Steve.......................................... T1-183 ..................................................................T1-251 ..................................................................T1-517 ..................................................................T1-523 ..................................................................T1-535 ..................................................................T1-765 Shaviv Edna..............................................T1-139 ..................................................................T1-177 Sherif Ahmed............................................. T1-807 Sheta Wael................................................ T1-517 Shue Shiu-Ya.............................................T1-269 Silva Cleide A.M. ...................................... T1-553 Silva Gonçalo............................................ T2-389 Silva Filho Demóstenes F.......................... T1-553 Sliwinsky Ben............................................ T2-533 Smith-Masis Michael................................. T1-59 ..................................................................T1-739 Soriano Hugo............................................ T1-207 Spanou Anastasia.................................... T2-527 Spiegelhalter Thomas................................ T1-651 Srivastav Shweta....................................... T2-637 Stasinopoulos Thanos N........................... T2-241 Stephan André........................................... T2-553 Stephens Cathal........................................ T2-521 Stevenson Fionn....................................... T2-17 Stojkovic Milena........................................ T1-565 ..................................................................T2-619 Stott Craig.................................................T1-363 ..................................................................T2-401 Straver Mark.............................................. T2-547 Suriyothin Phanchalath............................. T1-307 Szücs Ágota.............................................. T1-409 Tablada De La Torre Abel.......................... T1-679 Takata Masahito........................................ T1-273 ..................................................................T2-465 Tan Chun Liang......................................... T1-219 Tan Beng-Kiang......................................... T1-499 Tan Erna....................................................T1-709 Tan Alex Yong Kwang................................ T1-715 Tardif Michel..............................................T2-425 Tascini Simone.......................................... T1-397 Tavares Márcia.......................................... T2-193 Taylor Melissa............................................ T1-145 ..................................................................T2-89 ..................................................................T2-435 ..................................................................T2-631 Tenorio G. S..............................................T1-95 Theodorson Judy....................................... T1-891 Thitisawat Mate......................................... T1-427 ..................................................................T1-595 Thuot Kevin............................................... T1-783 Tian Wei....................................................T2-139 Toe Doris Hooi Chyee............................... T1-457 Topouzi Marina.......................................... T2-35 Torgue Henry............................................. T1-421 Toth Bianca................................................T2-47 Touceda Maria Isabel................................ T1-733 Trachte Sophie......................................... T2-217 Trebilcock Maureen................................... T2-327

Tsangrassoulis Aris.................................... T1-475 ..................................................................T1-583 Tsitoura Marianna...................................... T1-439 Tsoutsos Theocharis.................................. T1-439 Tweed Chris..............................................T2-71 Ulloa Mirentxu........................................... T1-387 Umakoshi Erica Mitie................................. T2-447 Uson Guardiola Ezequiel........................... T2-483 Valesan Mariene........................................ T1-727 Valkhoff Hans............................................ T1-333 Van Den Ham Eric..................................... T1-601 van Moeseke Geoffrey.............................. T1-697 ..................................................................T2-41 Vander Werf Brent D................................. T1-631 Vatavuk Paulo............................................T1-189 Verbeeck Griet........................................... T2-157 ..................................................................T2-541 Verhoeven C..............................................T2-279 Versele Alexis............................................T1-751 ..................................................................T2-279 Vianna Eduardo......................................... T2-407 Vicente Romeu.......................................... T2-199 Wallemacq Véronique.............................. T2-119 Walsh Vincent............................................ T2-401 Wan Li.......................................................T2-315 Ware Jacob............................................... T2-645 Wargas De Faria Ricardo.......................... T1-169 WasimYahia Moohammed......................... T1-589 Wattanapailin Wannee............................... T1-307 Wauman B.................................................T2-279 Weber Willi................................................T2-625 Weijers Jeroen........................................... T2-547 Weissenstein Charline............................... T1-257 Weytjens Lieve.......................................... T2-157 Wheeler Andrea......................................... T1-65 Whitman Christopher J.............................. T1-327 Widder Lynnette........................................ T2-53 Widera Barbara......................................... T1-113 Wigenstad Tore.......................................... T1-511 Wilson Robin............................................. T1-313 Wong Nyuk Hien........................................ T1-219 ..................................................................T1-239 ..................................................................T1-445 ..................................................................T1-709 ..................................................................T1-715 Wong James Pow Chew........................... T2-101 Xianhong Liu.............................................T2-339 Xuan Huang..............................................T1-745 Yahia Moohammed Wasim........................ T1-577 Yamakawa Mary A..................................... T1-119 Yiu Kam Po................................................T1-213 Yoshida Tamon.......................................... T1-273 Yu Gao......................................................T2-339 Zahiri Sahar...............................................T1-523 Zambrana Alejandra................................. T2-441 Zapata Gabriela......................................... T2-71 Zebun Nasreen Ahmed............................. T2-163 Zeiler Wim.................................................T1-53 ..................................................................T1-163 ..................................................................T2-351 ..................................................................T2-357 Zhou Tiegang........................................... T2-315 Zilka Leanne.............................................. T1-319 Zinzi Michele.............................................T1-357

913

With the major financial support of :

With the financial support of :

PLEA 2011 - 27 Conference on Passive and Low Energy Architecture, Louvain-la-Neuve, Belgium, 13-15 July 2011. The 27th PLEA conference PLEA2011 - Architecture and Sustainable Development marks the 30th anniversary of PLEA. The topics of the conference tackle a broad range well beyond the subject of energy. Following from the last PLEA conference that was held in Quebec in 2009, we want this celebratory PLEA 2011 in Louvain-la-Neuve to provide a special meeting ground for architects, engineers and researchers to debate the theme of sustainable architecture and the different aspects of sustainable development that range from the scale of the city to those of materials and components. This book of Proceedings presents the latest thinking and research in the rapidly evolving world of architecture and sustainable development through 255 papers which were selected out of more than 750 abstracts that were proposed by authors coming from over 60 countries. th

ARCHITECTURE & SUSTAINABLE DEVELOPMENT PLEA2011

27 th INTERNATIONAL CONFERENCE ON PASSIVE AND LOW ENERGY ARCHITECTURE LOUVAIN-LA-NEUVE 13 - 15 JULY 2011 Conference Proceedings Volume 1

d’architecture, architecturale, d’urbanisme,

ISBN 978-2-87463-278-5

9 782874 632785