DISSERTATION
NET ZERO ENERGY BUILDING
SUBMITTED BY: (NALIN GOEL) (ROLL NO.- 1332781057) GUIDED BY:(AR. AKSHITA DAS) IN PARTIAL FULFILLMENT FOR THE AWARD OF THE DEGREE OF BACHELOR OF ARCHITECTURE IN ARCHITECTURE
SUNDERDEEP COLLEGE OF ARCHITECTURE (DASNA, GHAZIABAD, UTTAR PRADESH
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Sunderdeep College of Architecture Ghaziabad
CERTIFICATE
This is to certify that the Dissertation titled “NET ZERO ENERY BUILDING” submitted by “Nalin Goel” as a part of 5 years Undergraduate Program in Architecture at SUNDERDEEP COLLEGE OF ARCHITECTURE is a record of bonafide work carried out by her under our guidance. The content included in the Thesis has not been submitted to any other University or institution for accord of any other degree or diploma.
Dr.Anju Saxena (Executive Director)
Ar. Akshita Bhatt
Ar.Devarpita Sikata (Dissertation Guide)
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Sunderdeep College of Architecture Ghaziabad
DECLARATION I Nalin Goel hereby declares that the dissertation entitled “NET ZERO ENERGY BUILDING” submitted in the partial fulfillment of the requirements for the award of the degree of B.Arch is my original research work and that the information taken from secondary sources is given due citations and references.
Nalin Goel 8th Semester B.Arch 2017-18
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ACKNOWLEDGEMENT I take this opportunity to acknowledge all those who have helped me in getting this study to a successful present status. I would like to express my deep sense of gratitude to my guide, Ar. Akshita Bhatt for her valuable suggestions and criticism. She made this possible. I extend my sincere thanks to my parents; they accompanied me to all my sites for the study and survey. All my batch mates for extending help and support, SDCA and all the other authorities which helped me in this study. I dedicate this work to my parents, friends,faculty etc. Once again I take this opportunity to thank all those who have directly or indirectly helped me and sincere apologies if I have forgotten to mention any one in particular.
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The choice before us is simple. “Will we continue to subsidize the dirty fossil fuels of the past, or will we transition to 21st century clean renewable energy?"
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ABSTRACT Net zero energy building (ZEB) are building with zero carbon emission and zero energy consumption respectively. The main challenge is to compensate for carbon emission from the production of material and construction by more energy than the building uses for its operation through renewable resources. In a global perspective, buildings are accountable for about 40% of all greenhouse gases. The primary objective is to develop solution for new buildings residential and commercial in order to bring a breakthrough for building with zero greenhouse gas emission associated with their construction, operation and demolition. A net-zero energy building (NZEB) is a residential or commercial building with greatly reduced energy needs. In such a building, efficiency gains have been made such that the balance of energy needs can be supplied with renewable energy technologies. A building that offsets all its energy use from renewable resources that are available within the footprint.
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Table Of Contents
CHAPTER 1: INTRODUCTION 1.1 Introduction…………………………………………………….. 13 1.2 Aim…………………………………………………………….. 13 1.3 Hypothesis……………………………………………………… 13 1.4 Objectives…………………………………………………….... 13 1.5 Scope and Limitations………………………………………….. 13 1.6 Methodology…………………………………………………… 14 1.7 Overview………………………………………………………. 14 1.8 Importance…………………………………………………….. 14-15 1.9 Need to Study………………………………………………… 15-16 1.10 NET ZERO ENERGY BUILDINGS: DEFINITIONS…………………. 16-17 1.11 BARRIERS TO NZEB………………………………………………….. 17-19
CHAPTER 2: DIFFERENT APPROACH FOR THE ZEB CONCEPT 2.1 Introduction………………………………………………… 20 2.2 Energy Supply Options and Priorities……………………... 20-21 2.3 Residential consumption of electricity in india……………. 21-22 7
2.3.1 Total Power Consumed by Appliances 2.3.2 Distribution of Power Consumed by Appliances 2.4 Net-Zero Energy Building Concepts and Assumptions……. 23-26 2.4.1 Grid Connection 2.4.2 Fuel Switching 2.5 Supply Options……………………………………………….. 26-30 2.5.1 Option 0 – Low-Energy Buildings 2.5.2 Option 1 – Renewable Energy Generated Within the Building Footprint 2.5.3 Option 2 – Renewable Energy Generated Within the Boundary of the Building Site 2.5.4 Option 3 – Off-Site Renewable Energy Used To Generate Energy On Site 2.5.5 Option 4 – Purchase or Install Renewable Energy Generated Off Site 2.6 Thermal Comfort in Built Form and climate study………… 31-36 2.6.1 Degree of Comfort index 2.6.2 Tropical climate 2.6.3 Sub-Tropical climate 2.7 Passive cooling technique…………………………………… 36-38
2.7.1 Wind tower 2.8 Climate change………………………………………………. 38-39 8
2.9 Parameters of NZEB……………………………………… 39-43 2.9.1 Energy efficiency methods CHAPTER 3: METHODOLOGY ………………………… 44-46 3.1 Result………………………………………………………. 47-48 CHAPTER 4: CASE STUDIES: 4.1 SHUNYA………………………………………………… 49-52 4.2 INDIRA PARYAVARAN BHAWAN…………………. 52-56 CHAPTER 5: CONCLUSION…………………………….. 57 REFERENCES……………………………………………… 58-59
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III. LIST OF ABBREVIATIONS
ZEBs
Zero energy building
NZEB
Net zero energy building
OCED
Organization for co-operative economic development
PV
Photovoltaic
REC
Renewable energy credit
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IV. LIST OF FIGURES
Figure 1: Zero energy building……………………………........................................16 Figure 2: Primary energy demand………………………………………………………21 Figure 3: Total Power Consumed by Appliances…………………………………………………..22 Figure 4: Distribution of Power Consumed by Appliances…………….............................................................22 Figure 5: Site Boundary of Energy Transfer for Zero Energy………………................................................................26 Figure 6: India climatic zone map………………………………………….………………...31 Figure 7: Degree of comfort …………………………………………………........................32 Figure 8: Courtyard Effect on Indoor Condition………………………………………………...….....36 Figure 9: Section of wind tower……………………………………….……………...........37 Figure 10: Flow of wind in through Wind tower with respect toindoor areas..18………………………………………………………..38 Figure 11: Cumulative energy-related CO2 emission………………...............................................................39 11
Figure 12: Building form and orientation…………………….40 Figure 13: Shading……………………………………………41 Figure 14: Insulated envelope………………………………...42 Figure 15: Thermal mass……………………………………...43 Figure 16: Net zero home…………………………………………………………..44 Figure 17: Steps to reduce energy consumption……………………………....................................45 Figure 18: Inside a net zero home…………………………………………………….…..…46 Figure 19: Net delivered energy…………………………………………….......................47 Figure 20: Energy reduction strategies ……………………………………..............................................48 Figure 21: Net plus energy building and efficiency path……………………………………………………………..48 Figure 22: Case study fig1………………………………………………….......................49 Figure 23: Case study fig2………………………………………………….......................50 Figure 24: Case study fig3………………………………………………….......................52 Figure 25: Case study fig4………………………………………………….......................53 12
CHAPTER I : INTRODUCTION 1.1 INTRODUCTION
1.2 AIM To study net zero building techniques for an office. 1.3 HYPOTHESIS Net zero office building is a result of energy efficiency and on energy generating measures.
1.4 OBJECTIVES
To understanding the concept of net zero building
To study the factors that are responsible for energy efficiency in a office building
To investigate new technologies used to generate energy
To analyze existing net zero buildings and do a comparative analysis
To derive factors that are most important to design a net zero building
1.5 SCOPE AND LIMITATIONS
Study will be limited to office buildings
Study will cater both live and literature case studies
No use of simulation software's will be used for analysis of the building
Project estimations (cost of the project) will not be considered as part of the analysis
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1.6 METHODOLOGY
First, it will carry out an in depth research on net zero energy in order and its techniques
Second, case studies will be presented and analyzed in terms of net zero energy.
Finally it will conclude with guidelines for net zero energy buildings for more efficient energy consumption.
1.7 OVERVIEW Buildings have a significant impact on energy use and the environment. Commercial and residential buildings use almost 40% of the primary energy and approximately 70% of the electricity in the world. The energy used by the building sector continues to increase, primarily because new buildings are constructed faster than old ones are retired. To combat the climate change issue, developing the city into a low carbon society is a global challenge. Low or zero carbon design is essential to achieve the carbon reduction target. Among all sectors, building industry is identified as the major contributor on carbon emission . There is a growing interest in the development of zero energy, zero carbon and carbon neutral buildings in the world.
1.8 IMPORTANCE A zero energy building (ZEB) produces enough renewable energy to meet its own annual energy consumption requirements, thereby reducing the use of non-renewable energy in the building sector. ZEBs use all cost-effective measures to reduce energy usage through energy efficiency and include renewable energy systems that produce enough energy to meet remaining energy needs. There are a number of long-term advantages of moving toward ZEBs, including lower environmental impacts, lower
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operating and maintenance costs, better resiliency to power outages and natural disasters, and improved energy security.
Reducing building energy consumption in new building construction or renovation can be accomplished through various means, including integrated design, energy efficiency retrofits, reduced plug loads and energy conservation programs. Reduced energy consumption makes it simpler and less expensive to meet the building‟s energy needs with renewable sources of energy.
ZEBs have a tremendous potential to transform the way buildings use energy and there are an increasing number of building owners who want to meet this target. Private commercial property owners are interested in developing ZEBs to meet their corporate goals, and some have already constructed buildings designed to be zero energy. In response to regulatory mandates, federal government agencies and many state and local governments are beginning to move toward targets for ZEBs. However, definitions differ from region to region and from organization to organization, leading to confusion and uncertainty around what constitutes a ZEB.
1.9 NEED TO STUDY The definition of ZEBs needs to include clear and concise language to be effective and accepted. Metrics and measurement guidelines are required to allow verification of the achievement of the key elements of the definition. The definition, nomenclature and measurement guidelines should address how energy consumption is measured and what energy uses and types to include in its determination. In practice, actual projects seeking to verify zero energy should work to ensure no harm is done in the process of achieving zero energy performance across other, nonenergy-related considerations, such as water protection, optimized comfort for lowload buildings, and comprehensive indoor air quality. While these considerations don‟t affect the definition of zero energy, it is important that in practice a design team 15
ensures that other important building considerations and values are not sacrificed in pursuit of zero energy.
(Fig.1)
1.10 NET ZERO ENERGY BUILDINGS: DEFINITIONS Net Zero Site Energy Building : ”A site ZEB produces at least as much energy as it uses in a year, when accounted for at the site.” Assume a building using 100 kWh of energy annually will be site NZE is atleast 100 kWh of renewable energy is produced anually at the site.
Net Zero Source Energy Building : ”A source ZEB produces at least as much energy as it uses in a year, when accounted for at the site” Source or primary energy is the measure of net zero status for source NZEBs.Primary energy is the energy used to generate and deliver secondary energy to the site. 16
Net Zero Energy Cost Building : Energy Cost Building „The amount of money the utility pays the building owner for the energy the building exports to the grid is at least equal to the amount the owner pays the utility for the energy services and energy used over the year.” A building is net zero cost energy if it recovers expenses on utility bills by selling electricity generated by renewable sources.
Net Zero Energy Emission Building : “A net-zero emissions building produces at least as much emissions-free renewable energy as it uses from emissions-producing energy sources” Emissions of net zero energy emissions building are counted for the source energy and not site energy. To determine emissions output from a building, energy used in the building is multiplied by an emissions factor which weighs emissions resulting from transportation and at-source generation.
1.11 BARRIERS TO NZEB If the strategy and technologies exist to build more energy efficient buildings, then the question is how come all buildings in the country are not moving towards net-zero. The fault may be in the traditional way of designing buildings as well as perceived associated higher costs with green buildings. Many architects still design buildings in the conventional way and giving thought the nature and potential of the site, they just fulfill the requirements of client and destroy environment. However, because many important architectural decisions are set at this point, few changes can be made that would improve energy performance. In contrast to the traditional building process, the whole-building design process requires the team, including the architect, engineers (lighting, electrical, and mechanical), energy and other consultants, and the building‟s owner and occupants, to work together to set and understand the energy performance goals. The full design 17
team focuses from the outset on energy and energy cost savings. The process relies heavily on energy simulation. To be effective, the process must continue through design, construction, and commissioning (Torcellini et al, 2006a). Despite the inherit benefits of reducing or eliminating energy costs, building owners ultimately ask how much of an investment must be made and what is the value of such an investment. The cost of such a project varies greatly depending on the strategy undertaken to reduce energy use and the climate in which the building is constructed.
EXAMPLES: Ministry of Power and the United States Agency for International Development (USAID) launched India‟s first integrated web portal designed to promote and mainstream Net Zero Energy Buildings (NZEB) in India. Currently, seven Zero Energy Buildings of India are listed below.
Building name
CEPT, A living
Building type
Climate Type
Office & Educational
Composite
Commercial
Composite
Commercial
Hot & Dry
Commercial
Composite
laboratory
Indira Paryavaran Bhawan, MoEF
Akshay Urja Bhawan, HAREDA, Panchkula, Haryana
Eco Commercial Building (ECB) Bayer Material Science
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Malankara Tea
Commercial
Warm & Humid
Commercial
Warm & Humid
Plantation
GRIDCO Bhubaneswar
Sun Carrier Omega Commercial
Hot & Dry
NZEB
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CHAPTER 2 : LITERATURE REVIEW DIFFERENT APPROACHES FOR THE ZEB CONCEPT
2.1 INTRODUCTION It is difficult to find a building, which can be named the first Zero Energy/Emission Building (ZEB). One of the reasons could be that maybe ZEB is not a new concept for a building, it is just a modern name for buildings, from times before district heating and electricity, heated with wood or straw and lighted with candles and domestic animals.
Nevertheless, in the late seventies and early eighties appeared few articles, in which phrases ‘a zero energy house‟, „a neutral energy autonomous house‟ or „an energyindependent house‟ were used. It was the time when the consequences of the oil crisis became noticeable and the issue of the fossil fuels sources and the energy use started to be discussed. However, those papers were mainly focusing on the energy efficient technologies and passive solutions implemented in the building. Furthermore, only energy demand for space heating, domestic hot water and cooling were accounted in the „zero‟, hence were they in fact buildings with zero energy use? Over the decades, in many articles and research projects number of ZEB‟s were described and evaluated, however almost for each case the ZEB was defined different or sometimes even no exact definition was used. Recently, the lack of common understanding and common definition for ZEB became noticeable and the world wide discussion has begun.
2.2
ENERGY SUPPLY OPTIONS AND PRIORITIES
Various supply-side RE generation technologies are available for NZEBs . Typical examples of these technologies include PV, solar hot water connected to a district hot 20
water system, wind, hydroelectricity, and biofuels. Demand-side RE and efficiency measures include strategies that save energy but typically are not commoditized. These cannot be included in the supply-side balance for achieving an NZEB. Typical examples of demand-side RE and energy efficiency strategies include passive solar heating, daylighting, solar ventilation air preheaters, and domestic solar water heaters. Guiding principles for RE in NZEBs were developed to minimize the energy transfers from generation source to end use and provide long-term maintainability in the built environment:
(Fig.2)
2.3 RESIDENTIAL CONSUMPTION OF ELECTRICITY IN INDIA 2.3.1 Total Power Consumed by Appliances
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(Fig.3)
2.3.2 Distribution of Power Consumed by Appliances
(Fig.4)
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2.4 NET-ZERO ENERGY BUILDING CONCEPTS AND ASSUMPTIONS 2.4.1 Grid Connection Before discussing the RE supply options available to NZEBs, we must look at the issue of grid connection. Conceptually, an NZEB produces as much as or more energy than it uses annually and exports excess RE generation to the utility (electricity grid, district hot water system, or other central energy distribution system) to offset the energy used. For NZEBs, a utility connection is allowed for energy balances. A grid-connected NZEB uses traditional energy sources such as electricity and natural gas utilities when on-site generation from RE does not meet the loads. When the on-site generation exceeds the building‟s loads, excess energy is exported to the utility. By using the utility to account for the energy balance, excess production can offset later energy use. We assume that excess on-site generation can always be sent to the grid to be fully used. However, in high market penetration scenarios, the grid may not always need this energy. In this scenario (and depending on the electricity utility), on-site energy storage would become necessary to maintain the zero energy status of the building. Off-grid NZEBs are also possible under this classification system; however, they typically require additional on-site generation capabilities combined with significant energy storage technologies. Backup energy sources for off-grid NZEBs would also have to be supplied with RE fuels under this classification system. 2.4.2 Fuel Switching The NZEB definitions and classifications enable renewable electricity generation to offset various fossil fuel energy uses. For example, natural gas energy use can be offset with excess photovoltaic (PV) or wind energy exported to the grid; the offset level is determined by the energy use accounting method. A site energy accounting allows for a 1-to-1 offset between fuels; source energy can place an additional offset (approximately 3-to-1) for renewable electricity exported to the grid.
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Table 1. NZEB RE Supply Option Hierarchy
Option
NZEB Supply-Side Options
Examples
number Reduce site energy use through energy Daylighting;
insulation;
efficiency and demand-side renewable passive solar heating; highbuilding technologies.
efficiency
0
heating,
ventilation,
and
conditioning
equipment;
natural
ventilation,
evaporative
air-
cooling;
ground-source heat pumps; ocean water cooling On-Site Supply Options 1
Use RE sources available within the PV, solar hot water, and building footprint and connected to its wind electricity
or
hot/chilled
located
on
the
water building
distribution system. 2
Use RE sources available at the building PV, solar hot water, lowsite and connected to its electricity or impact hydro, and wind hot/chilled water distribution system.
located on parking lots or adjacent open space, but not physically mounted on the building
Off-Site Supply Options 3
Use RE sources available off site to Biomass,
wood
pellets,
generate energy on site and connected to ethanol, or biodiesel that the building‟s electricity or hot/chilled can be imported from off 24
water distribution system.
site, or collected from waste streams from on-site processes that can be used on
site
to
generate
electricity and heat 4
Purchase recently added off-site RE Utility-based sources,
or
other
equivalent
wind,
REC emissions credits, or other
programs. Continue to purchase the “green”
purchasing
generation from this new resource to options. maintain NZEB status.
PV,
All
off-site
purchases must be certified as recently added RE. A building
could
also
negotiate with its power provider
to
install
dedicated wind turbines or PV panels at a site with good
solar
or
wind
resources off site. In this approach,
the
building
might own the hardware and receive credits for the power.
The
power
company or a contractor would hardware.
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maintain
the
Site Boundary of Energy Transfer for Zero Energy
(Fig.5) 2.5 SUPPLY OPTIONS This section presents a brief discussion about the various energy supply options listed in Table 1. 2.5.1 Option 0 – Low-Energy Buildings
Option 0 states that a building must reduce site energy use through demand-side RE and energy efficiency technologies. Option 0 is considered a prerequisite and is an essential and fundamental quality of NZEBs. A well-optimized NZEB design should include energy efficiency strategies to the point that the available RE strategies become more cost effective.
Efficiency measures or energy conversion devices such as daylighting or natural gasfired combined heat and power devices are not considered to be on-site, supply-side 26
RE production in the NZEB context. Any RE source such as passive solar space heating, solar thermal air heaters, ground-source heat pumps, and natural ventilation that cannot be commoditized, exported, and sold, are considered to be demand-side technologies and efficiency measures. Combined heat and power systems that use fossil fuels to generate heat and electricity are considered to be demand-side technologies.
2.5.2 Option 1 – Renewable Energy Generated Within the Building Footprint
This option covers all energy generated and used (or exported) from RE sources collected within the building footprint. Option 1 renewables apply only to a single building and to the RE connected directly into its energy distribution infrastructure. RE that is generated and used within the building footprint is directly connected to the building‟s electricity or hot water system, which minimizes transmission and distribution losses. This includes RE technologies mounted on the building roof or façade. Typical Option 1 technologies include PV and solar thermal systems. Building-mounted wind turbines may also have some limited application.
Building-mounted RE technologies are preferable because the collection area can be guaranteed to be available over the life of the building. Other permanent structures could include non-buildable land and parking, and are considered in Option 2. Systems mounted within the boundary of the site, but not on the permanent building structure, could have a greater chance of being shaded, blocked, or removed because of future development needs for adjacent land.
Typically, the only area available for on-site energy production that a building has guaranteed as “its own” over its lifetime is within its footprint. To ensure this area is available for on-site production, many states, counties, and cities have solar access ordinances that declare the right to use the natural resource of solar energy as a property right. For example, the City of Boulder, Colorado, has a solar access 27
ordinance that guarantees access to sunlight for homeowners and renters. This ordinance protects the solar access of existing buildings by limiting the amount of shadow that new development may cast on neighboring buildings, and maintains the potential for using RE systems in buildings (City of Boulder 2006). Using a PV system within the boundary of the building site to generate electricity is less favorable than a roof-mounted PV system because the area outside the building‟s footprint could be shaded or developed in the future. Thus, it cannot be guaranteed to provide long-term generation.
Fuel cells and microturbines that use natural gas do not generate RE and exported energy would not count toward any of these options; rather, they typically transform purchased fossil fuels into heat and electricity. This can be a valuable source-energy efficiency strategy. Energy that cannot be used by the building at the time of generation and must be exported is not counted for the purposes of defining an NZEB. 2.5.3 Option 2 – Renewable Energy Generated Within the Boundary of the Building Site This option addresses RE generated on the building site but not within its footprint or mounted on the building. On-site RE is ideally connected directly to the building‟s electricity, hot/chilled water, or other building energy systems; however, on-site RE does not necessarily have to be directly connected if the RE equipment can be shown to be located on the building‟s site using a commonly accepted site definition.
The on-site RE must be located on the property, or on property geographically contiguous to the property, on which the building is located, except that the two properties may be separated by an easement, public thoroughfare, transportation, or utility-owned right-of-way. Non-contiguous properties owned by the same organization but connected by a right-of-way which is controlled and to which the public does not have access, is also considering onsite property.
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The site is typically defined as the property boundary; however, sites should represent a meaningful boundary that is functionally part of the building. When using this option, the site must be defined and justified
Typical strategies include parking lot PV systems mounted to shading structures, tower-based wind turbines mounted in a neighboring field, and ground-mounted solar hot water systems connected into the building‟s hot water distribution system. An on-site solar-thermal absorption chiller would also be considered under this option. When available, biomass harvested from the site and used in the building (or exported) is also considered a site RE resource, as long as the resource is renewable over the life of the building.
2.5.4 Option 3 – Off-Site Renewable Energy Used To Generate Energy On Site
RE resources from outside the building site boundary (Options 3 and 4 in Table 1) could arguably also be used to achieve an NZEB. Often, high energy use buildings such as hospitals, laboratories, and grocery stores do not have sufficient RE generation capacity available within the building footprints or within the site boundaries. Our NZEB classification recognizes this, and was developed so all buildings could potentially reach NZEB. NZEBs that require significant off-site RE can achieve net-zero energy consumption under this classification system. However, it is not the same as a building that generates all needed energy on site and is classified as such.
Renewable sources such as wood pellets, ethanol, and biodiesel that are imported to the site can be valuable, but are less valuable than on-site renewable sources in the NZEB context. Option 3 is less preferable than Option 1 or 2 because of the energy used and the carbon footprint associated with producing and transporting the renewable resource to the building site. A building could qualify as an NZEB by 29
using RE sources that are available off site, importing them on site, and then using them to generate energy on site. An example of this would be wood chips imported to heat a building. Other off-site renewables covered under this option include waste vegetable oil, biodiesel, and ethanol. Methane from human and animal waste treatment processes, recovery of waste energy streams from industrial processes, or landfill gas collection are all possible off-site RE generation options covered under Option 3, if they are available over the life of the building. 2.5.5 Option 4 – Purchase or Install Renewable Energy Generated Off Site This option addresses purchased RE generated off site that has been certified as a newly installed source. Typical examples include utility-based wind, RECs,) or other equivalent rating organizations. For a building to use this energy option and be considered an NZEB, the off-site RE generated must be a recently installed and certified RE source. This new grid-based renewable resource must also be available and purchased for the building to maintain an NZEB status.
A variation on this option could be an organization that puts into place strict efficiency goals and negotiates with its power provider to install off-site dedicated wind turbines or PV panels at a local or regional off-site location with better solar or wind resources. In this approach, the organization might finance or own the hardware (or a portion of the system) and receive credits for the power. The power company or a contractor would maintain the hardware. The building owner would probably also pay a charge to the utility to “transport” this energy. This would be a stronger commitment than buying new RECs.
A building that purchases all its RE has little incentive to reduce building loads. Through these avenues, a building could qualify as zero energy even if it directly consumes a large amount of energy generated from fossil fuels. The intentions might be good, but this type of building is the least optimal classification of an NZEB and may not reduce energy consumption overall. The NZEB classification system responds by valuing this renewable resource at the bottom of the classification. 30
2.6 Thermal Comfort in Built Form and climate study Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment, simply put our body feels at harmony with the climat ic condition surrounding us. Our daily life comprises states of activity, fatigue and recovery, and thus it is essential that the mind and body recovers through recreation, rest and sleep to counter balance the mental and physical fatigue and for that we need to have place where we can minimize or eliminate unfavourable factors.
(Fig.6)
India have an extraordinary variety of climat ic regions, ranging from tropical in the south to temperate and alpine in the Himalayan North, where elevate regions receive sustained winter snowfall. Land area in the north of the country has a semi-tropical climate with severe summer. A condition alters with cold winter. In contrast to areas in south where they have tropical climate where warmth is unvarying and rains are frequent.
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2.6.1 Degree of Comfort index.
(Fig.7) Through designing, planning, use of different methods and use of mechanical devices we can create a space in which we can achieve thermal comfort. Under extreme conditions, when human existence is at risk, mechanical controls and positively necessary but when the conditions are such that only the degree of comfort is in questionwhen the risk is a slight discomfort- use of mechanical controls is optional. The environment immediately outside and between buildings can be influenced by the design of a settlement and by the grouping of buildings can be influenced by the design of settlements and by the grouping of buildings to a minor extent. Structural means of control which include design of sun shade device, pergolas, courtyards, and other methods can provide a further levelling out the climatic variations and often comfort conditions can be achieved by such means. Precisely controlled indoor climate can only be achieved by mechanical (active) controls. As an Architect we can
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design adequate structural control in order to provide comfortable built space and reduce the load on mechanical controls, thus making it more economical.
2.6.2 TROPICAL CLIMATE
Generally this climatic zone has hot, sticky condition and continuance presence of dampness and air temperature remains 21° and 32°C with little variation between day and night. Humidity is observed to be high during all seasons. Wind direction is constant but slow.
A) Physiological Objectives that we face here: Heat loss to the air by convection as conduction is negligible because the temperature of the outside air remains almost the same throughout the day and night, a the storage of heat during the day. Some degree of comfort can be achieved by encouraging outdoor breezes to pass not only through the building, but across the body surface of the occupants. There is no significant cooling down at night, the wall and roof surface temperature tend to even out and settle at the small level as the temperature
B) Design approach –
As movement of air is the only available relief from climatic stress, therefore vital to indoor comfort, the building will have to be opened up to breezes and orientated to catch whatever air movement there is.
Open elongated plan shapes with a single row of rooms to allow cross ventilation accessible from open verandahs or galleries. 33
Extended plans in a line across the prevailing wind direction afford low resistance to air movement and it therefore the ideal solution
Door and Window opening should be as large as possible free passage of the air.
Free from effect of outside obstruction.
Ventilat ion- exchange of air is necessary between roof and ceiling in case
C) Airflow and Opening –
In elation with prevailing breezes to permit natural airflow large fullyopen able windows should be used; there is no point in having windows with fixed glass panes.
Plant cover of the ground tends to create a steeper wind gradient than an open surface i.e. it restricts the movement of air near the ground, thus building on stilts or having habitable rooms on upper floors is also an option.
Shading of all vertical surface of both openings and solar wall will be beneficial
2.6.3 SUB-TROPICAL CLIMATE
Broadly these zone are characterized by very hot, dry air and dry ground with day time air temperature being between 27-44 degrees. Humidity is mostly found to be between moderate and low. Little or no cloud cover is observed to reduce the high intensity of direct solar radiation.
A) Physiological Objectives that we face here: Reduction of the intense radiation. Low level of humidity results in evaporations which is greater here than in any other climate Breezes cannot be used to benefit the indoors, unless theair is cooled and dust is filtered out.
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B) Design approach – In order to counter these conditions an enclosed and compactly planned building is most suitable and by placing as much accommodation as possible under one roof, thermal loading from sun and hot air will be considerably lessened. Surface exposed to the sun should be reduced as much as possible.
Larger dimensions of a building should face North and South as they receive lowest heat load from solar radiation and by aligning buildings closely mutual shading will decrease the heat gains on external walls. Non- habitable rooms can be effectively used as thermal barriers if planned and placed on east and west side.
Shading of roofs, walls and outdoor spaces is critical. Projecting roofs, deep veranda, shading devices, trees and utilisation of surrounding wall and buildings can be used in this purpose. Using low thermal mass for shading devices closed to opening to ensure their quick cooling after sunset.
Construction of 2nd roof over first or a simple ceiling with roof-would be very effective in reducing the effect of thermal gain of roof. Best external space is courtyard. It is an excellent thermal regulat ion in many ways and a pool of cool night air can be retained (being heavier than warm air).High wall cuts off line the sun, and large areas of the inner surface and courtyard floor will be shaded during daytime.
C) Roof, wall and opening– Basic method of utilising the large diurnal temperature variation consist of use of large thermal capacity structures which will absorb much of the heat entering through the outer surface during the daytime, the inner surface temperature would show any appreciable increase.
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Courtyard Effect on Indoor Condition (Fig.8)
D)Ventilationduring day times opening should be closed and shaded. Ventilat ion will not reduce the radiant heat transfer, but by lowering the temperature of the inside surface of the outer skin, it will reduce the radiant heat emission of that surface.
2.7 PASSIVE COOLING TECHNIQUES Above mentioned design approaches need not be enough to create a comfortable indoor environment and passive cooling techniques can be incorporated into the design in order to use natural elements to achieve thermal comfort. Main objectives that are in focus in these techniques are 1-Exclude unwanted heat gains 36
2-Generate cooling potential wherever possible The best way of dealing with unwanted heat gains is to prevent it from reaching building surfaces in the first place.
2.7.1 Wind Tower Wind towers are generally used in hot and dry climates for cooling purposes. A prerequisite for using a wind tower is that the site should experience winds with a fairly good and consistent velocity. The cardinal principle behind its operation lies in changing the temperature and thereby density of the air in and around the tower. The difference in density creates a draft, pulling air either upwards or downwards through the tower.
Section of Wind Tower (Fig.9)
Variations and controls:
Variations in wind tower design can be achieved by altering tower heights, cross section of the air passages, locations and numbers of openings, and the location of the 37
wind tower with respect to the living space to be cooled. The variations are aimed at providing the desired air-flow rates, heat transfer area and storage capacity. Air flow through different parts of the buildings can be controlled by the doors and the windows. It may be noted that wind towers are for use only in the summer and must be closed properly in winter.
Flow of wind in through Wind tower with respect to indoor areas (Fig.10)
2.8 CLIMATE CHANGE The threat of climate change is forcing us to contemplate a total re-design of our built environment and of all the products and services that we consume.. Climate change is 38
thought to happen primarily because of increased anthropogenic emissions of green house gases. One of the major greenhouse gases is carbon dioxide. As buildings account for almost 50% of carbon dioxide emissions the alteration of practices related to the construction and use of buildings will have a significant role in achieving these targets
(Fig.11)
Two-thirds of global of the world's greenhouse-gas emissions come from the energy sector. The IEA projects that energy-related CO2 emissions will increase by 20% by 2035. 2.9 PARAMETERS OF NZEB: 1. Energy Efficiency methods 2. Energy Generation methods
2.9.1 ENERGY EFFICIENCY METHODS: An energy efficient building balances all aspects of energy use in a building: lighting, space-conditioning and ventilation, by providing an optimized mix of passive solar design strategies, energy-efficient equipment‟s and renewable sources of energy. 39
Implementation of passive design principles is the first stepping stone on the path to zero. i) Passive design strategies:
NZEB must sharply reduce energy use, and only then it must use renewable system to fulfill its energy needs. For less renewable system one has to really go low on energy saving. Passive design strategies are climate specific approaches which helps us to reduce energy usage in our building. (1) Building form & Orientation:
Form and orientation constitute two of the main passive design strategies, for reducing energy consumption and improving thermal comfort in a building. By this we can control the amount of sun falling on a surface, or the wind flow etc. To achieve NZEB these play a vital role in design approach as these strategies can harness the sun and wind flow on a building.
(Fig.12)
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(2) Shading: Well-designed sun control and shading devices, either as part of the building or separately placed from a building façade, can dramatically reduce building peak heat gain and cooling requirements and can improve the natural lighting quality of building interiors. By this we can greatly reduce the need of mechanical heating or cooling to maintain thermal comfort inside buildings. Shading devices can thus be used as an essential solution for achieving energy efficiency.
(Fig.13)
(3) Insulated envelope: Thermal insulation in walls and roofs reduces heat transfer between the inside and outside and helps maintain comfortable indoor temperature. It provides healthier environment, adds sound control, and most important lowers the electricity bills. 41
Insulation helps keep indoor space cooler in summer months and warm during winters. There are variety of materials to choose from including fibre glass, mineral wool, rock wool, expanded or extruded polystyrene, cellulose, urethane or phenolic foam boards and cotton. Insulation is rated in terms of R‐value. Higher R‐values denote better insulation and translate into more energy savings, much needed to meet NZEB design goals.
(Fig.14)
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(4) Thermal mass: Thermal mass helps to store heat within the building structure and can change the indoor temperature in comparison to outer temperature. This heat storing capacity of building materials helps in achieving thermal comfort for occupants by providing time delay. Hence, choosing appropriate building materials can largely effect the level of comfort within buildings. To meet NZEB design parameters, selection of building materials hold utmost importance in modulating indoor temperatures and hence reducing conventional energy loads. Thermal mass regulates the temperature of the space by controlling the amount of thermal energy stored in the building. Heavy thermal mass buildings can keep the spaces comfortable for several hours even after the HVAC system is switched off.
(Fig.15)
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CHAPTER 3 : METHODOLOGY
(Fig.16)
Most zero net energy buildings get half or more of their energy from the grid, and return the same amount at other times.
The most cost-effective steps toward a reduction in a building‟s energy consumption usually occur during the design process. To achieve efficient energy use, zero energy design departs significantly from conventional 44
construction practice. Successful zero energy building designers typically combine time tested passive solar, or artificial conditioning, principles that work with the on-site assets. Sunlight and solar heat, prevailing breezes, and the cool of the earth below a building, can provide day lighting and stable indoor temperatures with minimum mechanical means. ZEBs are normally optimized to use passive solar heat gain and shading, combined with thermal mass to stabilize diurnal temperature variations throughout the day, and in most climates are super insulated.
Steps to reduce energy consumption (Fig.17)
Sophisticated 3-D building energy simulation tools are available to model how a building will perform with a range of design variables such as building orientation (relative to the daily and seasonal position of the sun), window and door type and placement, overhang depth, insulation type and values of the building elements, air tightness, the efficiency of heating, cooling, lighting and other equipment, as well as local climate. These simulations help the designers predict how the building will perform before it is built, and enable them to 45
model the economic and financial implications on building cost benefit analysis, or even more appropriate – life cycle assessment.
Zero energy buildings are built with significant energy saving features. The heating and cooling loads are lowered by using high efficiency equipment, added insulation, high efficiency windows, natural ventilation, and other techniques.
Inside a zero energy home(Fig.18) Zero energy buildings are often designed to make dual use of energy including white goods, for example, using refrigerator exhaust to heat domestic water, ventilation air and shower drain heat exchangers, office machines and computer servers, and body heat to heat the building. These buildings make use of heat energy that conventional buildings may exhaust outside.
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3.1 RESULT:
The zero net energy consumption principle is viewed as a means to reduce carbon emissions and reduce dependence on fossil fuels. Connection to energy grids prevents seasonal energy storage and oversized on site systems for energy generation from renewable sources like in energy autonomous buildings.
Net delivered energy (Fig.19)
Requirement for energy austerity is reduced
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Energy reduction strategies (Fig.20)
Energy efficiency is improved
Net plus energy building and efficiency path (Fig.21)
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CHAPTER 4 : CASE STUDIES 4.1 SHUNYA 'Shunya' is showcased at sector 107, Noida. The model home is the first-of-its-kind energy-efficient residential structure that is enriched with green architectural excellence, the fruitful endeavour by 3C, which is dedicated to addressing global issues of climate change, shrinking supplies of fossil fuels and other natural resources.
(Fig.22)
The 24 solar panels generating 3KWH energy is sufficient to run the house on its own making it energy self-sufficient. The house consumes 80-90% lesser energy to run as compared to a conventional house, the model home project promises to cut water use by 40% percent.
With Shunya, The 3C Company, the only realty developer in the entire Asia Pacific region which has Three Platinum and Four Gold rated LEED certified Green 49
Buildings to its credit, marks the grand emergence of Noida in Green architectural excellence.
(Fig.23) The 3C Company unveiled the first of its kind net zero energy home at the Acrex India 2011. The showcased model illustrates how a common man can contribute in restoring the health of our Planet Earth by adapting sustainable living standards and reducing his carbon footprint without compromising on the comforts and aesthetics one
always
aspires
in
a
home.
Inspired to shape a sustainable future, the company showcased the net zero energy home at the 12th edition of the Acrex India Expo 2011 which is being organized at Pragati Maidan. The 3C Company, which has played an instrumental role in the green building revolution aims to generate awareness about latest environment friendly designs and concepts, which are also being implemented in the green residential projects of the company. This energy efficient house Utilizes renewable energy from 50
sun to make it independent of any electricity grid. The energy efficient home would add to the tranquil experience of the dweller.
Committed to deliver a sustainable tomorrow, this initiator of green developments has been working on the concept of a net zero energy home for quite some time now. The company has already launched a residential project „Lotus Panache‟ which is the home to Asia‟s first Net Zero Pre Nursery School. Vidur Bharadwaj, Director, The 3C Company & the man behind the Green Revolution says, “At the Three C Company we have always strived to set benchmarks in eco friendly designs. In an effort to highlight our technical excellence in creating sustainable buildings, we are showcasing a working model of a net zero energy home, here at the Acrex India Expo. The fully functional model displayed is of a self sustainable home which is environment friendly and can fulfil its energy demands through the help of solar panels and other innovative techniques
Ar. Sheetal Rakheja, Partner, D&D (Design & Development) exclaimed, “It gives us great pride to be associated with this innovative, first of its kind Zero energy consuming building. It is expected to change the dynamics of real estate in the times to come. By lowering dependence on the depleting non renewable energy sources, the building also consumes very less water and is mainly constructed out of the waste material. This energy efficient structure will further contribute towards the numerous efforts taken by us to reduce carbon footprints.”
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(Fig.24)
4.2 INDIRA PARYAVARAN BHAWAN
This is a project of ministry of environment and forests for construction of new office building at New Delhi.
The basic design concept of the project is to make the net zero energy green building.
First in government sector targeted for both ratings of green building (5 star Griha, Leed India PLATINUM)
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(Fig.25)
a) PROJECT DETAILS:
-up area : 3,1400 m2
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b) ENERGY EFFICIENCY i. Building Form & Orientation:
Planned in 2 parallel blocks facing the North-South direction, with a larger linear court in the center.
Emphasis on the North & South for Optimal Solar Light but cutting Solar Heat, bringing the Greens in.
Effective ventilation achieved by orientating the building East- West and by optimum integration with nature by separating out different blocks with connecting corridors and a huge central court yard.
ii. Courtyard:
Creates a natural connection with rest of the landscaping on site, also helps in cross ventilation within the building and also acts as a interacting space.
iii. Stack effect:
Due to difference in air pressure hot air rises up in the courtyard and cold air stays down cooling the temperature in courtyard.
iv. Evaporative cooling:
Water bodies are provided in the central courtyard so that sensible heat of air evaporates water, thereby cooling the air, which, in turn, cools the temperature of the building.
v. Shading devices:
The fenestration shading is appropriate for the entire building and the reduction in the window to wall ratio helps to lessen the heat gain as well the need of high design efficiency glass. Appropriate shading from summer sun is provided while allowing in winter sun.
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vi. Active chilled beam system:
A chilled beam is a type of convection HVAC system designed to heat or cool large buildings such as commercial buildings, schools, universities, dry labs, and hospitals. A chilled beam primarily gives off its cooling effect through convection by using water to remove heat from a room. This system saves air handling unit‟s fan power by 50 kW.
vii. Geo-Thermal cooling:
Condenser water heat shall be rejected to earth by boring at suitable depth & sending hot water at 100°F (37.8° C) & back at 900 F (32.2° C). Enormous water saving since no make-up water is required. Saves cooling tower fan energy.
c) ENERGY GENERATION:
i. Photovoltaic Solar Energy:
For optimum use of solar energy the whole rooftop and projections are covered with solar panels with a 5-degree tilt. Solar power plant of 930 kWph capacity is being installed in an area of 6000 sq. m. This plant is expected to generate about 14 lakh units (kWh) of energy annually.
Total Saving in building:
The estimated savings from various Energy Efficient Measures are :
Lighting :- 66342 kWh/year
Air conditioner :- 58186 kWh/year
Exhaust Fans :- 5081 kWh/year
Total Projected Saving :- 129609 kWh/year
ECBC 2007 Lighting Power Density
Actual 11.8 W/sqm
5 W/sqm 55
HVAC load
20 sqm/Tr
40 sqm/Tr
Total
100 W/sqm
40 W/sqm
It saves 40% in Electricity : a. Solar Passive architecture b. Insulated outer walls and roofs c. Windows with special glass(double glazed) transmitting more light and less heat d. Energy efficient LED lights with sensors e. Chilled beam system of air conditioning with <50% of conventional energy consumption f. Geothermal heat exchange system g. Regenerative lifts h. Energy efficient equipment
55% Saving in Water and Zero Discharge:
a. Recycling of waste water after treatment b. Geothermal heat exchange system c. Low flow fixtures, sensor urinals & Dual flow cisterns d. Low Water Consuming plants
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CHAPTER 4: CONCLUSION Net zero building, is a building with zero net energy consumption, meaning the total amount of energy used by the building on an annual basis is roughly equal to the amount of renewable energy created on the site.They do at times consume nonrenewable energy and produce greenhouse gases, but at other times reduce energy consumption and greenhouse gas production elsewhere by the same amount. Most zero net energy buildings get half or more of their energy from the grid, and return the same amount at other times. Buildings that produce a surplus of energy over the year may be called "energy-plus buildings" and buildings that consume slightly more energy than they produce are called "near-zero energy buildings" or "ultra-low energy houses".
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REFERENCES John C. Sawhill, Richard Cotton, Energy Conservation: Success and Failures Brookings Institution Press.
David Elliott, Energy, Society & Environment: Technology for a sustainable future, Brookings Institution Press . Azmi Zain Ahmed, Energy Conservation, Intech.
Esbensen, T.V. & Korsgaard, V. (1977). Dimensioning of the solar heating system in the zero energy house in Denmark. Solar Energy Vol. 19, Issue 2, 1977, pp. 195-199
Gilijamse, W. (1995). Zero-energy houses in the Netherlands. Proceedings of Building Simulation „95. Madison, Wisconsin, USA, August 14–16; 1995, pp. 276–283.
Web address: http://www.ibpsa.org/proceedings/BS1995/BS95_276_283.pdf Iqbal, M.T. (2003). A feasibility study of a zero energy home in Newfoundland. Renewable
Energy Vol. 29, Issue 2 February 2004, pp. 277-289
Kilkis, S. (2007). A new metric for net- zero carbon buildings. Proceedings of ES2007. Energy
Sustainability 2007, Long Beach, California, pp. 219-224
Laustsen, J. (2008). Energy Efficiency Requirements in Building Codes, Energy Efficiency 58
Policies for New Buildings. International Energy Agency (IEA).
Web address: http://www.iea.org/g8/2008/Building_Codes.pdf
Mertz, G.A., Raffio, G.S. & Kissock, K. (2007). Cost optimization of net-zero energy house. Proceedings of ES2007. Energy Sustainability 2007, Long Beach, California, pp. 477488
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