Design & Maintenance Guide 22

Design & Maintenance Guide 22

Building energy management management systems

SPECIALIST SERVICES, FUELS AND MECHANICAL DEFENCE ESTATES MINISTRY OF DEFENCE LONDON: The Stationery Office January 2001

DMG 22 Building Energy Management

© Crown Copyright 2001

Published with the permission of the Ministry of Defence on behalf of the Controller of Her Majesty's Stationery Office Applications for reproduction should be made to The Copyright Unit, Her Majesty's Stationery Office, St. Clements House, 2-16 Colegate, Norwich NR3 1BQ ISBN 0 11 772934 5

First Published 2001

Printed in the United Kingdom for the Stationary Office TJ 3543 3543 C1 O 05/01 05/01

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Foreword

This Guide has been produced by Defence Estates (DE), Central Business Unit, Specialist Services, under the patronage of the Defence Utilities Working Group.

The purpose of this Guide is to provide assistance to Project Sponsors, Property Managers, specifiers, designers, energy managers and operators in the procurement, use and maintenance of Building Energy Manag ement Systems (BEMS). Due to the wide potential readership, a chart has been prepared overleaf showing topics likely to be of specific interest to particular readership groups. Whilst this Guide was commissioned by the DE for use on Ministry of Defence (MOD) contracts, it is acknowledged that it could be usefully applied to other contracts. DE commends the use of this document by other Government Departments. It may also be used by non-government organisations. However, no warranty is given as to the accuracy of the content of this Guide, or its fitness for any purpose.

When this Guide is used in connection with a Defence contract then it shall be read in conjunction with further documents setting out particular contractual requirements.

This Guide has been compiled for the use of the Crown, its technical advisors and contractors in execution of contracts for the Crown. The Crown hereby excludes all liability (other than liability for death or personal injury) whatsoever and howsoever arising (including, but without limitation, negligence on the part of the Crown, its servants or agents) for any loss or damage however caused where the Guide is used for any other purpose.

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Building Energy Management Systems

Foreword

The following table provides guidance to the reader on which sections of the Guide are most likely to be of particular relevance to each type of reader:

Executive Summary 1 Introduction

2 Feasibility, design, procurement 3 Installation, commissioning performance testing 4 BEMS operation

5 BEMS maintenance 6 Energy monitoring and targeting

Analysis of requirements Tender summary Energy consumption benchmarks

Glossary of Terms Bibliography Very significant General interest Background information

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Acknowledgements

This Guide has been compiled by consulting engineers Ove Arup & Partners. The authors would like to record their gratitude to the staff at the following seven sites within the MOD Estate for their time and co-operation in researching the study:

R N Ensleigh, Bath RNAS Yeovilton RAF Brampton RAC Centre Bovington, Wareham RSS Blandford RAF Coningsby Defence Procurement Executive, Abbey Wood, Bristol Gratitude is also extended to the Building Services Research and Information Association (BSRIA) whose published guidance has been used in the production of this document.

CONTACT FOR QUERIES

Specialist Services Defence Estates Blakemore Drive Sutton Coldfield West Midlands B75 7RL Tel No: 0121 311 2294

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Abbreviations

BEMS

Building Energy Management System

BMS

Building Management System

BSRIA

Building Services Research and Information Association

CIBSE

Chartered Institution of Building Services Engineers

CPU

Central Processing Unit

DDC

Direct Digital Control

DE

Defence Estates (Formerly Defence Estates Organisation)

DEO

Defence Estates Organisation

EWC

Establishment Works Consultant

HVAC

Heating, Ventilation and Air Conditioning

HVCA

Heating and Ventilating Contractors Association

IT

Information Technology

M&T

Monitoring and Targeting

OEM

Original Equipment Manufacturer

PC

Personal Personal Comp uter

PFI

Private Finance Initiative

PPM

Planned Preventive Maintenance

PPP PP P

Public Private Partnership

scs

Structured Cabling System

VAV

Variable Air Volume

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viii

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Contents

FOREWORD ACKNOWLEDGEMENTS ABBREVIATIONS CONTENTS EXECUTIVE SUMMARY

Section 1

INTRODUCTION

1.1 1.1

1.5 1.6

AIMS AND OBJECTIVES TERMINOLOGY WHAT IS A BEMS? HISTORY ADVANTAGES AND DISADVANTAGES OPTIONS AND FUTURE DEVELOPMENTS

Section 2

FEASIBILITY, DESIGN AND PROCUREMENT

2.1

GENERAL

2.2

FINANCIAL APPRAISAL INDICATIVE COSTS JUSTIFICATION FEASIBILITY

1.2

1.3 1.4

iii V

vii ix xi

1 1 1 2

4 6 7

STANDARDS AND REGULATIONS REGULATIONS COPYRIGHT

9 9 9 10 10 13 13 13 14 14 15 16 17 17 18

Section 3

INSTALLATION, COMMISSIONING, PERFORMANCE TESTING

19

3.1 3.2

INSTALLATION

19 20 22

2.3 2.4 2.5 2.6 2.6.1 2.6.2 2.6.3 2.7 2.8 2.9 2.10 2.11

3.3

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DESIGN AND SPECIFICATION

Design Specification Types of Specification PROCUREMENT COMMUNICATIONS SOFTWARE

COMMISSIONING DRAWINGS AND DOCUMENTATION

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Contents

Section 4

BEMS OPERATION

4.1

OPTIONS FOR MANAGING BEMS

4.1.1 4.1.2 4.2

Examples of the functions of staff who operate and manage BEMS Other Options

4.3 4.4 4.5

TRAINING

Section 5

BEMS MAINTENANCE

5.1

PREAMBLE

5.2 5.3 5.3.1 5.4 5.5

MAINTENANCE COSTS

Section 6 6.1 6.2 6.3

OUTLINE SPECIFICATION FOR LEVELS OF BEMS OPERATOR

COSTS OF OPERATING BEMS UPGRADING AND REFUBISHMENT OF BEMS

CONTRACT ARRANGEMENTS

Operating and Maintenance Documentation SPARES AND CONSUMABLES RECOMMISSIONING ENERGY MONITORING AND TARGETING

REVIEW AND RELATIONSHIP WITH BEMS ADVANTAGES AND POTENTIAL COST SAVINGS COST IMPLICATIONS

ANNEX A - TYPICAL COSTS AND SAVINGS ASSOCIATED WITH BEMS ANNEX B - ANALYSIS OF REQUIREMENTS ANNEX C - TENDER SUMMARY

23 23 24 25 25 27 27 27

29 29 29 29 30 30 31 33 33 34 35 37

39 43

ANNEX D - ENERGY CONSUMPTION BENCHMARKING

FOR MOD BUILDINGS GLOSSARY OF TERMS ASSOCIATED WITH BEMS BIBLIOGRAPHY

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Executive Summary

A Building Energy Management System (BEMS) is a computer based centralised system that helps to manag e, control and monitor particular engineering services within a building or group of buildings. Use of a BEMS can limit energy costs and labour requirements by improving plant efficiency and effectiveness. It can also provide a more comfortable environment for the building occupants and act as a focal point for alarms. BEMS have evolved from being a simple supervisory control tool to a totally integrated computerised control and monitoring system.

Some advantages that a BEMS can provide are:

simple operation with routine and repetitive functions programmed for automatic response flexible time scheduling of plant and heating to meet site changes such as holidays, training exercises and operational requirements remote switching of plant and adjustment of set points

faster and better response to occupant needs reduced energy costs through centralised control, monitoring and energy management programmes ability to cycle/control site electrical demands

better management through automatic alarm reporting, historical records and maintenance programmes graphical representation of plant operating conditions improved operation through integration of sub-systems (eg. lighting and access) improved plant performance and life expectancy real time collection and recording of data for imp roved an alysis of equipment or energy uses. To obtain a successful BEMS installation: provision needs to be made for ongoing operation and maintenance

operators must be skilled and fully trained on the use and operation of BEMS existing plant (when being overlaid with a new BEMS) must be capable of performing its required functions

the system needs to be correctly specified, installed, commissioned and operated.

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Executive Summary

This Guide sets out: the functions of a BEMS how to justify a BEMS

information required for a feasibility assessment design and specification aspects guidance on procurement

pointers for satisfactory installation and commissioning the importance of record documentation

the need for ongoing operation and maintenance the key role played by trained personnel.

xii

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1

1.1

Introduction

AIMS AND OBJECTIVES

The principal purpose of this Guide is to provide a single source of information regarding BEMS for those involved with: selection

design installation

testing commissioning

use maintenance.

It provides background inform ation, particularly for those who have little detailed knowledge of such systems. Further guidance is given in Specification 47 - Building Energy Management Systems, due to be published in 2001. This Guide is intended to:

provide a history of BEMS list their advantages and disadvantages address how to justify the application of BEMS assess feasibility at a specific location

identify requirements for installation, testing and commissioning

explain the importance of operation and maintenance demonstrat e their potential for energy monitoring and targeting.

1.2

TERMINOLOGY

BEMS is a generic term used to describe computer-based control systems for engineering and building services such as air conditioning, lighting, access, security, monitoring etc. Other titles used for such equipment are Building Management System (BMS) and Energy Management System (EMS). The term BEMS has been identified as the normal acronym for such systems and adopted throughout this Guide. Other terms are synonymous with this.

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Section 1 Introduction

1.3

WHAT IS A BEMS?

A BEMS is a computer-based system that helps to manage, control and monitor building engineering services within a single building or a group of buildings. Such a system, when properly designed, installed, commissioned and operated will significantly improve the operational efficiency of the engineering installation and its cost effectiveness in terms of labour and energy costs. It can also help to provide a more comfortable environment for the building occupants. A BEMS typically has at least one principal operator position (or central station), connected via a communication network to remote outstations (or controllers), which can function independently and provide local control to the plant to which they are connected. They can also collect and respond to data from the central station or other outstations. The central station is a user interface at which various functions can be available depending on the client's requirements. It may be located remotely eg. at a headquarters building or works department. Figure 1 demonstrates the components of a BEMS.

Figure 1 Components of a BEMS

Other Operator Interface

BEMS Central Station (Personal Computer)

Remote Operator Interface

SITE DATA NETWORK

Controllers

Hanger

Accommodation Block

Group HQ

Unitary controllers serving dedicated plant Room chiller unit

Heating pipework

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VAV

terminal - box

AHU

Standby generator

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Figure 2 illustrates how the BEMS controller functions.

Figure 2 Example of BEMS in operation

Temperature sensor

Time schedules (contained within the controller)

Humidity sensor

Velocity sensor Sensor inputs

Elements of building engineering services with potential for control or monitoring by a BEMS are: 

heating

•

ventilation

•

air conditioning

•

domestic hot and cold water

•

lighting

•

electrical supply/distribution

•

electrical standby services

•

energy consumption (ie. reading electricity, gas, water meters)

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electrical maximu m demand security/access equipment fire detection/alarm systems

vertical transportation specialist equipment (eg. standby facilities, smoke control and fume cupboards etc.)

catering services (eg. ventilation, electricity and water usage) There is no reason, however, why any system needing to be monitored remotely could not be integrated into a BEMS to provide a central focus point. Most current generation BEMS provide the management interface at the central station through a personal computer (PC). The operating system for the central station is likely to be Microsoft Windows, since this has become an industry leader. The component structure below the central station comprises a communication network, local controllers and field devices (eg. sensors, actuators and meters). Different suppliers use different communication protocols to transfer data, and within different generations of equipment from a single supplier there may be variations in communication standards. Where differen t suppliers equipment exist, or different generations of the same supplier, it may be possible to integrate the control components, but due to different communication standards and operating criteria this may not be a straightforward process. As this integration can be expensive, costs should be compared to replacement with directly compatible equipment. CIBSE note in their Energy Efficiency in Buildings Guide (published in 1998), that energy savings of between 10% and 20% can be achieved through the use of a BEMS, compared with independent controllers for each system, though opportunities for savings of this size will not always be available.

1.4

HISTORY

The development and processing power of computers, and in particular microprocessors, has enabled a steady growth since the late 1960s from separate, independent and dedicated control equipment to increasing degrees of automation, control and communication. One driving force was to reduce the amount of cabling by the use of data networks. Early systems were structured around a central computer called the 'head end' or 'front end' which contained the processing capability, linked by fixed wiring to each sensor or actuator device (eg. a room thermostat or a motorised valve). Although the processing capability was limited, only providing start/stop control and system monitoring, a central facility became available where all control and performance information could be accessed such as alarms, room temperatures and on-off switching times. This reduced the need for frequent site visits and hence offered more efficient use of maintenance operatives. Because the central processor carried out all the functions, the system capability was limited by the available capacity. Such systems were generally very inflexible and not user friendly.

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The next development was the introduction of direct digital control (DDC) and the reduction of the dependence on the central computer by distributing the computing power round the building or estate within local microprocessors, each with a limited input/output capacity. This style of system became known as 'distributed intelligence'. System design and operational requirements determined the need for a central computer. This was not essential because the system 'intelligence' was provided by the outstations. Provision of a communication network to link the outstations and allow data to be passed between them promoted the stand-alone outstations to a BEMS. Use of BEMS for control and monitoring of building services significantly increased over the decade from 1980. Interest increased also in the potential to link Heating, Ventilation and Air Conditioning (HVAC) equipment controls using BEMS for at least alarm monitoring from other stand alone systems such as lighting, lifts, fire and security and providing a single point for alarms to be registered. As computer processing power increased and costs reduced, the capabilities and applications of BEMS grew, though on occasions the installations became difficult to manage. Installation standards were not always followed, commissioning became difficult and not always effective, which resulted in systems that failed to achieve their original expectations.

Building owners and operators became disenchanted with "automated systems" which failed to deliver the promised solution. However, they accepted that if the systems could be simplified, designed properly, installed correctly and fully commissioned, they would be a useful tool for running properties. As microprocessor technology developed, stand-alone controllers became operated alone or linked through a communication network to other controllers and a central point of information access. Such units, where they serve terminal units such as fan coil units or Variable Air Volume (VAV) boxes have becom e known as unitary controllers. Plant manufacturers or Original Equipment Manufacturers (OEMs) , purchase unitary controllers and fit them to their own products. These can provide an opportunity for later integration into a BEMS through a communication network. Computer power has now become fully distributed, with the central computer becoming the 'host' for loading programmes, interrogating performa nce and recovering data. Systems have also become more user friendly and easier to programme.

Figure 3 Summary of changes in BEMS technology

BEMS with outstations

1970

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1980

1990

2000



1.5

ADVANTAGES AND DISADVANTAGES

The use of a BEMS provides an integrated computer based facility for the control and monitoring of the building engineering services.

Advantages are: routine and repetitive functions are programmed and responded to automatically (eg. daily on and off times, holiday scheduling, operational programming for d ifferent buildings, periodic testing of standby plant)

relatively simple operation for trained users (eg. access to detailed information such as room temperatures to monitor plant performance; modifying operating times to match changes to building use) quick response to occupant complaints about environmental conditions (the sensitivity of BEMS can highlight potential problems and allow adjustments to be made before occupants initiate complaints) reduced energy consumption and hence costs by central monitoring and control (savings may be up to 10% by constant fine tuning to match occupational needs) ability to cycle or control site electrical demand improved management information such as historical records, alarm logs and hours run can demonstrate that environmental criteria have been achieved; alarms have been actioned and plant maintenance can be more precisely managed

graphical representation of plant operating c onditions and in ternal environment, providing quick and simple understandin g of the information presented integration of system control and operation through so ftware links (allowing increased opportunities for fine-tuning of controls to the particular application) improved plant performance and life expectancy (eg. by establishing key operating criteria and monitoring performance efficiency).

Disadvantages that can apply include: any BEMS installation will have costs associated with it. These will not only be the initial design and installation, but also the subsequent operation and maintenance (see para 2.1) possible disruption to normal plant operation during BEMS installation need for a skilled operator to ensure maximum use is made of the system the effective potential of a BEMS can be very sensitive to proper specification, full consideration of condition and ability of plant to be controlled, commissioning by a skilled BEMS specialist and continued maintenance difficulty in in tegrating with existing equipment especially regarding communication protocol or the need for new controls or sensors to allow integration

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requires commitment at all levels throughout its operational life to maintain maximum effectiveness unless carefully chosen, certain aspects of BEMS can become obsolete relatively quickly

unless correctly specified, installed, maintained and operated BEMS can increase costs and environm ental impacts.

1.6

OPTIONS AND FUTURE DEVELOPMENTS

The processing power of electronic equipment being used within a BEMS means that any system needing to be controlled or remotely monitored could be accommodated, providing the cost of the initial installation and ongoing operation and maintenance can be justified.

Greater integration between different systems such as lighting, fire alarms, security and BEMS is likely to develop as the full capabilities become recognised. The links at present tend to be for monitoring and alarm reporting. As users investigate different options and the potential of the full equipment, greater confidence will be developed. Whilst communication standards do exist, different suppliers and manufacturers still have their own for their respective systems. As clients begin to demand system integration to allow data from different components and systems to be viewed and managed centrally, and control functions to be enhanced by sharing data, greater flexibility will be achieved. The components of BEMS from different suppliers are expected to become more compatible. Unitary controllers are likely to become standard items of plant and equipment. This may also influence the move towards communication standards, as greater integration between suppliers equipment will be required. Unitary controllers can provide programmable memories for field devices such as temperature sensors or valve actuators, allowing them to be programmed and commissioned before delivery to site. On-site commissioning will, however, always be required. The costs of outstations and central stations will be influenced by the continuous developments of IT equipment, w ith the expectation that greater processing capability will be obtained for less cost. The cost element of a BEMS taken up

with the installation of the communication network may be reduced where an IT network is available. Alternatively, the use of radio communications for both internal and external links has considerable potential to grow and develop, particularly between field devices and their associated outstations. Overall costs of BEMS are unlikely to reduce. Whilst some components such as electronic equipment may become cheaper, other hardware costs and the system design and engineering will continue to be the major proportion of the price and not provide opportunities for savings. As the volume of data increases, the levels of management information will rise. Exception reporting, to show potential problem areas with likely causes and possible solutions, may be developed to enable full use to be made of the available information.

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2

Feasibility, design and procurement

GENERAL This section helps to identify the factors for choosing a BEMS and provides guidance in establishing the feasibility and requirements for a BEMS. The most common reasons for considering the use of BEMS are: for new builds where costs are comparable to other forms of control

to replace existing old or failing controls where the difference in costs are outweighed by the benefits provided by the BEMS to improve the system where the benefits outweigh the costs where there is a need for stringent control and monitoring levels of building services.

2.2

FINANCIAL APPRAISAL

A key factor in building a business case for a BEMS will be a financial appraisal over the proposed life of the system. Annex A is a simple table to help provide initial indications of the likely costs and savings associated with BEMS. MOD Guidance and Policy for carrying out full financial appraisals is given in:

JSP 414 Part 4 Chapter 16 Investment Appraisal and Post Project Evaluation DEO (Works) 1996 DEO Technical Bulletin 96/04 - Through Life Costing

DEO (Works) 1996 DEO Technical Bulletin 96/03 - Value Engineering

MOD Guide to Investment Appraisal and Evaluation. Further guidance is also given in: Appraisal and Evaluation in Central Government (Treasury Guidance 1997)

Appropriate local guidelines should also be followed.

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Section 2 Feasibility, design and procurement

2.3

INDICATIVE COSTS

As general background information, three generic types of installation are considered with outline cost information based on Quarter One year 2000. These are not intended to be used for budget purposes, only to provide outline guidance of the order of costs for the different types of properties. The particular requirements for a specific location may result in significant variations from these figures. Total installed cost of BEMS (new greenfield site)* Property Type One

Very large major site with nume rous buildings and facilities eg. Naval Dockyard; RAF Operational Site Total utilities cost per annum (electricity, oil, gas, water) £1 million. Property Type Two Medium to large eg. Large single building or com plex of buildings Total utilities cost per annum £200,000. Property Type Three Small to mediu m single building or small complex of

£300,000

£75,000

£30,000

buildings Total utilities cost per annum (electricity, oil, gas, water) £50,000 * Installation in existing buildings will require an increase of 10% to allow for additional design and installation costs.

2.4

JUSTIFICATION

All building services need controls. BEMS can be cheaper than individual controls, particularly for new buildings where they can be justified on first costs for almost all types of buildings. For refurbishme nt or replacement situations, first costs alone may not indicate that a BEMS is appropriate. Whole life costs should also be investigated when system flexibility, monitoring and central control capability can be taken into account. Upgrading costs will need to be compared with potential energy savings. CIBSE indicate energy cost savings between 10% and 20% by use of BEMS in their 1998 Energy Efficiency in Buildings Guide. As a rule of thumb, a retr ofit BEMS can yield a 10% direct fuel cost saving against a reasonably well maintained conventional control system when properly designed, installed and commissioned. The benefits of using a BEMS are the flexibility of the controls available, communications capability (particularly for operational data between plant and system) and overall performance monitoring.

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A BEMS can provide three key advantages over stand alone control: provision of management information

remote operation, interrogation and alarm monitoring

greater flexibility and range of control strategies. BEMS will not compensate for fundamentally inefficient buildings and plant. Benefits of a BEMS can include:

improved environmental (eg. temperature) and time control from central

location rapid communication (system monitoring, operation and c ontrol) with remote sites, without physical visits improved comfort for building occupants

automatic fault reporting at central location (with predetermined levels of action) monitoring and targeting of energy consumption allows easy trial and monitoring of building response characteristics and related energy saving proposals such as lunch time set back of heating. graphical representation of plant perform ance and enviro nmental conditions. Examples of specific capabilities of BEMS are: scheduling plant start / stop times fuel consumption recording / energy metering

plant sequencing / optimisation filter condition monitoring

electrical maximum demand limiting lift monitoring

lighting control hours ru n recording and trend logging security management alarm handling

'at a glance' information p resentation. Whilst these are also available using stand-alone controls, integration into a BEMS provides the opportunity for achieving the greatest savings and operating efficiency.

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In addition to the technical capabilities listed above, BEMS can provide the opportunity for improved financial control, for example, by billing sub-tenants where suitable metering is provided. Close monitoring of occupancy times and adjusting BEMS settings can produce energy savings. Reduced maintenance attendance by scheduling work on an hours run basis can lead to manpower savings. Before purchasing such a system, it is important to consider what the controls are intended to do and how they will achieve this. To provide a framework for this, Annex B - Analysis of Requirements provides a series of questions to help analyse requirements at a specific location, including a pro forma to identify which plant and services are to be covered by the BEMS. The particular plant or system will generally determine the type of control required. Each control requirement should be considered separately and the details listed. It is important to avoid an over specified or unnecessarily complex control system for the particular application. Advice on what is necessary and appropriate, and help on completion of the check list can be obtained from the Establishment Works Consultant (EWC) through the Property Manager or through the Establishment Energy Focal Point.

The larger the number of systems or plant items listed for the project, and the larger the numbe r of control or monitoring requirements, then the greater is the likelihood for a BEMS to be the appropriate choice for controlling the building services. For an existing installation, a list of questions to consider is given below: •

is there an operational requirem ent for central monitoring or control?

•

do the existing controls meet curre nt good practice? (eg. time control, weather compensation, optimum start/stop)

•

can the existing control be adequately operated and maintained?

•

does energy use compare well with published guidelines? (see Annex D Energy consumption benchmark s for existing MOD buildings)

•

is there a need to attribute responsibility for utilities to specific users? (eg. billing of non-entitled users and resource accounting)

•

are consumption records needed for tarif f/con sumption profile analysis?

•

is there an opportunity to integrate control of differ ent engineering services?

•

has the building function changed?

•

have good housekeeping measures to reduce energy consumption been carried out.

•

are the buildin g occupants satisfied with their environment?

These questions are included in Annex B - Analysis of Requirements Once a decision in principle has been taken to consider a BEMS, the full potential benefits and costs of achieving them need to be examined.

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2.5

FEASIBILITY

BEMS are becoming the norm in many larger new buildings, as their first cost is similar to stand alone controllers. In existing buildings, assessing the feasibility of a BEMS can be more difficult. Where existing stand alone control equipment is available, the suitability, practicality and cost of retaining and incorporating components of it into a larger BEMS needs to be assessed. The following considerations are aimed at existing buildings, but could also be applied to new buildings. •

Zoning of Building Services

Are these adequate for energy efficient operation and match current and proposed occupant requirements? •

Primary Plant

Does this have stand alone control, could it be linked with a BEMS? •

Existing stand alone controls Are they still supported by manufac turers? Ca n they be economically integrated into a new BEMS? Control equipment installed in the late 80s, early 90s or earlier may have limited functions available and be difficult to reprogramme.

•

Existing BEMS Is there an existing BEMS available that could be used?

2.6

DESIGN AND SPECIFICATION

2.6.1

Design

A BEMS is a powerful tool that allows building owners, operators, and managers to understand the function and control the operation of engineering plant and services for which they have responsibility. It is important to note that however a BEMS is designed or specified it can only control within the limits and accuracy of the equipment to which it is connected. There are a wide variety of systems available that can provide control or simply monitor the status of plant. A purchaser needs to be clear and unamb iguous about the plant and equipment to be served by the BEMS and the degree of control required.

The extent and method of design will depend on the size and complexity of the installation and its controls, the technical competence of the client and any relationship which exists with a preferred supplier. Where the BEMS is being overlaid on existing plant and equipment, control devices such as sensors and actuators may not be compatible or suitable for connection to the BEMS. Allowance for this will need to be included in the costs of the work.

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Control of different engineering systems such as HVAC, lighting, major plant items such as chillers, and life safety (eg. fire) has traditionally been kept independent. BEMS can provide opportunities fo r a degree of integration, but this is likely to be limited to alarm monitoring or sequence initiation. The extent of integration will be governed by the risks involved. Plant that is safety critical, has military operational implications or operates u nder its own dedicated control system may not be appropriate for integration.

2.6.2

Specification

The objectives of a specification are to:

provide a firm basis tor a tender identify required performance criteria minimise misunderstanding define responsibilities provide like for like comparisons between different proposals. The specification provides basic information together with exact functional requirements, where appropriate, for the specific application. Further detailed guidance regarding this is provided in Specification 47 - Building Energy Management Systems to be published in 2001. The initial step when preparing a specification is to define the building management strategy from which a specification can be developed. To achieve maximum benefit the strategy must take account of the functi on of each building and the existing or proposed operation and maintenance manpower availability. For large, complex applications it may be appropriate to appoint a professional advisor for this role. Advice on this can be obtained from the EWC through the Property Manager, or through the Establishment Energy Focal Point.

2.6.3

Types of Specif ication

Two generic types of specification can be identified: Performance

states how the system will operate in strategic terms, with an outline description of what is to be controlled and monitored.

Functional

gives detailed requirements for the system, including control and monitoring strategies and the devices included, such as controllers, sensors and actuators.

Both types of specification should describe the features to be provided, standards to be met including materials and workmanship, testing and commissioning requirements, training to be carried out and guarantees to be provided. The type of specification will be dictated by the particular application and intended procurement strategy. Where a specialist controls contractor is to be used and competence has been demonstrated and proved on similar work, a performance specification may suffice. The same type of specification may also be appropriate for buildings with relatively simple engineering services and no need for elaborate control. However, where a building has complex plant such as full air conditioning, or where environmental conditions have to be closely controlled within strict limits and there are considerable inter-relationships betw een the control sequences, a functional specification will be required to ensure the client's requirements are fully defined and able to be interpreted by the supplier

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and installer. Care m ust be taken to ensure BEMS equipment is compatible with all systems and its operation does not allow plant to operate outside manufactures parameters, normal duty ranges or operational limits. In 1998 The Building Services Research and Information Association (BSRIA) published a Library of Control Strategies (Application Guide AG7/98) as a reference document for when the controls are being developed, specified and configured. The strategies can be used when specifying control systems as an independe nt source of control solutions. The provision of this Libra ry does not remove the onus from designers to ensure that an appropriate working solution is produced.

To create a specification for a particular installation from the strategies within AG7/98 the designer needs to: •

decide which 'plant functio ns' are required to make up the whole system

•

decide for each plant funct ion which of the available plant modules options is to be used

•

for strategies which offer alternatives or options, decide which are required in the specific application.

2.7

PROCUREMENT

A number of options are available. These include:

direct purchase from a specialist supplier of controls equipment direct purchase from a systems integrator (who obtains components such as controls equipment from a specialist supplier and designs, installs and commissions the system to meet the user's requirements) use of a controls specialist to design the system, tender the work and oversee installation and commissioning produce in-house, an outline brief of requirements and tender the work for purchase produce in-house, an outline brief of requiremen ts and tender fo r leasing an installed BEMS (where such a leasing agreement is deemed appropriate). The lease agreement may include upgrades to the BEMS over the stated period of the lease agreement. incorporate the BEMS installation within a Private Finance Initiative (PFI)/Public Private Partnership (PPP) arrangement. lease the BEMS through the Facilities Management Contractor.

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2.8

COMMUNICATIONS

Two aspects of communications need to be considered: 1.

The information being communicated. Computers need precise, rigidly defined rules and protocols for successful communication. Typically, translation problems occur when trying to connect products made by different manufacturers, or in some cases, different versions of products made by the same manufacturer. Traditionally, different systems such as lighting, HVAC and life safety (eg. fire ) have had separate, dedicated controls. Relevant specialists should be fully consulted where safety critical systems are to be connected to a BEMS.

Communication standards allow transfer and interpretation of data between different parts of the BEMS and integration of equipment from differen t suppliers. There is no single agreed communications standard, at present, followed by all BEMS suppliers. Several exist and are being used by different suppliers. 2.

Physical communication system between all parts of the BEMS (eg. data cabling).

The elements of a BEMS need to be linked together to transfer data through a communication network. The most common method is data cabling using shielded or unshielded twisted pair. Other options include fibre optics, which can provide increased security, radio links, which may be more appropriate when long distances (eg. across an operational RAF site) are involved, mains borne signalling, where the electrical distribution system is suitable and modem links to public or private telephone networks. Existing communication network cabling may be available, eg. redundant voice systems, but will need to be checked and proved suitable before inclusion into the project scheme. Dedicated voice networks using modems, can provide a basic communication infrastructure, particularly on extensive sites where buildings are spread over a large area. This application can result in prolonged times for data transfer and problems with data accuracy which may have implications if used for generating energy bills. Alternatively, an existing IT cabling system may be available. Office accommodation in particular is increasingly likely to have a structured cabling system providing an infrastructure on each floor, with a grid of outlet connections allowing connection of IT equipment such as PC's and printers. BEMS may be able to use this to link major components directly together (eg. controllers and the central sta tion). The cost of integra ting a BEMS with an IT structured cabling systems (SCS) will depend on how much of the SCS is required. Where it is proposed to use an existing or proposed general use cabling system for a BEMS, application for this must be made in sufficient time to ensure its availability when required. The continuing availability of shared access to the system also needs to be confirmed.

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January 2001

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If the SCS is installed at the same time as the BEMS (eg. on a green field development) it can be designed to accommodate the BEMS requirements and installed by the SCS installer.

Other benefits of using the IT network are shared network maintenance costs, access to a robust and industry recognised communication network and an enhanced network security (faults detected and rectified more quickly than normal BEMS network). Use of an IT network is likely to be for the major data interconnections such as between controllers and the central station. Use of a local BEMS network is more likely to be cost effective for individual plant controllers. Radio communications applied to BEMS are very limited but offer potential for future growth. It has been successfully adopted on large MOD sites such as operational RAF stations with considerable distances between buildings, to reduce the need for cable links. The technology can be applied both internally between field devices and associated outstations and externally over a campus type environment for communications between remote buildings. Security of radio communication systems may not be satisfactory for particular locations.

2.9

SOFTWARE

The software elements of a BEMS determine how the controls and monitoring functions built into it will operate and communicate. This level of software may be termed the 'firmware' since they can be fixed components of the system whose operating parameters and characteristics are set up to match the specific requirements. The BSRIA Library of Control Strategies provides a set of standards. Individual suppliers may opt for particular ways to achieve each strategy. BEMS software imposed above the control strategies provides the monitoring and reporting structure of the system, including how and what reports, alarms and historical logs are generated. Documentation for both the firmware and software is critical because it will define how each controller and control parameter has been configured, how information is stored and reports are generated. Software protection in terms of licence agreements needs to be resolved at an early stage of the project. Copies of the software should be held in secure locations, ideally both on and off site.

2.10

STANDARDS AND REGULATIONS

BEMS installations mu st comply with all relevant statutory regulations. Other guidance in terms of standards and codes of practice should also be noted. Examples of these are British Standards Codes of Practice and MOD guidance. The following is a general list of some areas that should be addressed when installing a BEMS:

a safe means of access for maintenance all BEMS panels are secured to prevent unauthorised access the central station and controllers are password protected to prevent unauthorised access

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sufficient illumination is provided as required for user operation of BEMS where they are situated in plant rooms. This may require additional task lighting. electrical installations comply with BS7671 1992 - Requirements for Electrical Installations (IEE Wiring Regulations 16th Edition). Commonly known as the Wiring Reg's all equipment complies with the standards relating to electromagnetic interference and is suitable for the particular application workstations comply with the Health and Safety (Display Screen Equipment) Regulations 1992 specific security needs for the particular application relating to hard ware, software, sensors and other electronic and IT equipment are followed.

2.11

COPYRIGHT

For a particular application, the detailed BEMS specification, software configuration, operating parameters and reporting structures established for the specific application will all be covered by MOD copyright and not, therefore, available to others without authorised agreement.

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3 Installation, Commissioning, Performance Testing

3.1

INSTALLATION

This is the process of translating the requirements set out in the specification into a physically completed system (static completion). It requires labour, materials, supervision, inspection, testing and documentation.

In a new installation the plant and equipment needing interconnection with the BEMS should have suitable facilities already available. For existing plant and equipment, where a new BEMS is being installed, there may be a need to replace or refurbish existing control devices such as sensors, actuators and analogue controls. Installation standards should be defined in the specification, including those for data cabling, programming, testing, documentation and cable identification. The installation of a BEMS can be critical to its effective and efficient performance. It is advised that installation should only be carried out, or closely managed, by specialist BEMS installers, or organisations who can demonstrate their particular expertise in this field. Safety and operational interlocks are likely to be included within the specific control strategies. These need to be identified in schedule format and proved to be working in a safe and correct manner. The BEMS would normally only monitor the action of such interlocks, particularly for critical operations. Tests to confirm an installation has been completed and approved to the satisfaction of the Project Manager should include:

•

an audit of the cabling and hardware

•

demon stration of the physical and logical integrity of the system

•

demonstration of all the control actions

•

demonstration of all the sensor calibrations

•

demonstration of the system software

•

demonstration of the system graphics

•

all documentation including drawings and operating and maintenance manuals have been provided.

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19


Section 3 Installation, Commi ssio ning, Performa nce Testing

3.2

COMMISSIONING

Commissioning is the process of turning a physically completed system into a fully operational working system that meets the designed requirements. Poor commissioning is the most common cause of BEMS failing to meet the initial performanc e expectations. This in turn can lead to unstable and under performing plant. Suppliers can benefit from good commissioning since subsequent warranty costs are likely to be less than for a poorly commissioned installation. A comprehensive specification supplemented with flow diagrams can form the basis of the commissioning checklist and serve as a yardstick to test the BEMS control strategies. It is beneficial to specify as much off-site testing as possible (eg. control panels, application software and graphics) when conditions are more suitable for testing and remedial work. Once installed, the BEMS should be fully pre-commissioned as far as possible,(eg. data cabling interconnections, validity of sensor readings, actuator performance). All controls are likely to be needed in 'manual' operation during full commissioning of the engineering services. The BEMS can then be integrated with the building services and finally commissioned and put into operation. Adequate time needs to be allowed for this, as a guide 30 minutes for each BEMS sensing point should be anticipated. Attendance will also be required by other trades and this should be reflected in the tender figures as part of the commissioning costs.

On sites where the BEMS is commissioned and handed over in stages, the sensors in the earliest stages may have drifted from the calibration setting by the time that later stages are commissioned. Where the BEMS is being installed in an operational building, careful planning is needed to maintain all services so that they continue to function during the commissioning process.

Whilst the initial commissioning will be carried out to the original design data, it is likely that fine tuning of the system will be required over the first full year of building occupation to fully meet the requirements of the building operator and the occupants. It may be appropriate to include this in the original contract cost, particularly for more complex installations. This will lead to greater savings as the BEMS operation and performance parameters can be optimised. Liaison between the building user/operator and the installation contractor during the period of fine tuning is important to ensure a full understanding of how the building is required to function. BSRIA Application Handbook AH 2/92, Com missioning of BEMS, provides a code of practice including detailed check lists. Other relevant publications are: BSRIA

CIBSE

20

January 2001

TM1/88

Commissioning HVAC Systems - Divisions of Responsibilities.

AG3/89.1

The Commissioning of Air Systems in Buildings

AG2/89.1

The Commissioning of Water Systems in Buildings

TM2/88

A Procedure for Commissioning VAV Systems

AG1/91

Commissioning of VAV systems in buildings Commissioning Code C Automatic Control

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Section 3 Installation, Commissioning, Performance Testing

Performance testing addresses the operation of the BEMS and the associated plant. It is aimed at ensuring both are operating in an optimum manner in terms of energy and internal environmental performance.

The BEMS operator should be trained to monitor the BEMS performance and to note and respond to feedback from the building occupants. Many BEMS receive little or no maintenance. Possibly this is because a BEMS is perceived as microprocessor based and not requiring attention. A BEMS is more than the central station or controllers. Sensors can go out of calibration, actuators can fail to operate. Building use will change over time, needing set points to be revised. Performance testing will detect changes to the BEMS level of performa nce and faults due to incomplete commissioning. Reasons for performance testing include: occupant complaints about the e nvironment energy performance is unsatisfactory system neglect little information may be available about the installed control regimes BEMS perform ance is inadequate/not satisfactory unsatisfactory environmental performance significant change to energy consumption to evaluate BEMS performance repeated failures or alarms need to be investigated. fits of performance testing are:

improved occupant comfort prevents complaints arising from occupants

energy savings reduced false alarms improved awareness of BEMS and control strategies confidence in BEMS records. BSRIA Application Guide AG2/94 - BEMS, Performance Testing, provides guidance on a general performance audit and help in resolving particular BEMS problems. Guidance on energy consumption benchmarks for MOD buildings can be found in the DETR Energy Conservation Guide 75 - Energy Use in Ministry of Defence Establishments. A copy of the s ummary page giving the benchmark figures fro m this document is given in Annex D.

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Section 3 Installation, Commissioning, Performance Testing

3.3

DRAWINGS AND DOCUMENTATION

Comprehensive and accurate record drawings and do cumentation are essential for the satisfactory operation and maintenance of a BEMS. These should include:

22

•

BEMS Performance Specification

•

writte n description of plant and how it is controlled

•

control strategy, including diagrams

•

operating and maintenance manual

•

maintenance schedules

•

central station software manu al

•

points list (all analogue and digital inputs and outputs)

•

flow diagram

•

specification s for sensors and actuators

•

schematic wiring diagrams for outstations, field devices and control panels

•

controls design specification

•

details of set points, alarm levels, time schedules, overload settings

•

commissioning data

•

plant diagrams showing locations of field devices

•

software back-u p copies

•

emergency procedures

•

handover/acceptance documentation

•

log book - to record incidents, operational informa tion and all changes made to the system (para 5.3.1 gives more information about this).

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4

BEMS Operation

4.1

OPTIONS FOR MANAGING BEMS

To achieve the full benefit of a BEMS installation it will need to be monitored, used and properly maintained rather than simply installed and ignored. The man/machine interface of a BEMS provides ready access to plant operating da ta, allows better understanding of the performance of the systems being controlled and helps improve decision making. As such, this interfac e is a key element of any BEMS. Due to the complexities of modern BEMS systems a common problem is identifying just who is responsible for what and in what context. To help eliminate this it is recommended that this is agreed a nd documented at the design stage, include operation, access, maintenance and communication responsibilities.

It is essential that all personnel authorised to access or use a BEMS are adequately trained to ensure safe and efficient operation of the system. Where personnel have the ability to control or effect equipment or plant controlled by the BEMS, they must be competent to do so. Risk Assessm ents and Safety Method Statements should be produced and used to ensure safe and correct operation and use of the BEMS. Individuals with the appropriate authority should be able to demonstrate their understandin g of the areas within the BEMS to which they have access, and any implications their actions may have relating to the Health and Safety of both themselves and others. Authorisation for access to the BEMS or plant rooms in which they may be sited, especially where plant/equipment settings and controls are involved, should be approved through the Property Manager and managed throughout by the Authorised Person. In turn the Property Manager should confirm with the Establishment Works Consultant (EWC) and Works Services Manager (WSM), or relevant service provider, that the individual requesting use/control of the BEMS is deemed competent for their specific requir emen ts. The EWC and WSM should also be able to confirm if there are any other implications regarding existing maintenance and operation contracts.

It would be beneficial for the main operators of BEMS to be longer term personnel who have a good understanding of the site and any necessary conditions or concerns. Where this is not appropriate/p ossible oper ator s can help by keeping records to pass on. Each new operator should receive full training for the system. Having regard to the above, Site Energy Managers would typically be included in those with access to BEMS at the highest level. This will help ensur e

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Section 4 BEMS Operation

maximum benefit from the BEMS in terms of energy management, efficiency and savings. Potential overlap between Site Energy Managers and the WSM must be discussed and agreed at the earliest stage in the BEMS design. This may, for example, lead to siting of BEMS controllers out of plant rooms to facilitate safe access by the Site Energy Manager.

4.1.1

Examples of the functions of staff who operate and manage BEMS

The hours noted overleaf are illustrative only and will depend on the particular site and application. Hours do not include for energy Monitoring and Targeting (M&T), or interpretation of consumption informa tion. A BEMS is a tool to aid the staff listed overleaf. As such, the installation and use of a BEMS, within the roles described, should represent savings in human resources, not demands on them. This is based on the princ iple that the BEMS should allow existing tasks to be done in less time. In addition, the improved quality and quan tity of information and rapid and flexible control of plant will allow much greater effectiveness of these tasks. Site Energy Manager

The typical emphasis of this role regarding BEMS is on improved energ y efficien cy and manage ment. Typical BEMS use for this role is seven hours per week. The role may typically include an understanding of how the engineering plant functions and be aware of the complexities, capabilities and design philosophy of the BEMS. The post holder 's functions could include regular checking of plant performance and environmental conditions, adj ustment of environmental conditions to meet changes in weather, occupa ncy or usage and bringing any other areas of concern to the atten tion of the Property Manager. The level of potential achieved from the BEMS in this role will strongly depend on the level of training, understanding, experience and delegated authority to take necessary action. Site Maintenance Staff/Consultants (Other Service Providers)

The typical emphasis of this role regarding BEMS is on maintenance and operation of the site infrastructure, without necessarily having any specific direction on energy management. Typical BEMS use for this role is three hours per week. The principle use of the BEMS in this role is to confirm plant is operating correctly, identify and respond to plant failure alarms and use information for proactive maintenance managemen t. In many cases, it will also include operation of plant and equipm ent. This role requires detailed unde rstanding of how the engineering plant functions and all aspects of the BEMS. Energy Warden (or Building Custodian)

This is often a supporting role to the Site Energy Manager or Property Manager, norm ally associated with a single building or small group of buildings. Typical BEMS use for this role is up to two hours per week. The role requires ready access to information from the BEMS such as time / environmental settings and actual conditions for the rele vant area(s) . Any anomalies can then be manually verified or investigated as required and recommendations made or action taken using local knowledge. A basic understanding of the relevant functions and capabilities of the BEMS would be beneficial. This role does not normally have authority for any control function but may have access for limited adjustment to environmental set points. 24

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Property Manager/EWC (Management)

This role primarily requires access to information from the BEMS to aid in the management role or provide clear and rapid understanding of relevant systems through the schematics. Use is depen dent on requir ement . Typical BEMS use would be up to one hour a week. Only a basic understanding of the plant or BEMS function or capability is required. This role would not normally access the control functions . Full understanding of plant or BEMS functions or access to the control functions would be achieved through the Site Energy Manager, WSM or EWC, as required.

4.1.2

Other Options

A Bureau Service could be used to provide 24 hour monitoring of BEMS alarms remote fro m the site. There may be scope for this function to be provided by the site security organisation when the main tenance contractor is not in attendance. Instructions on how to respond to each alarm type or priority level would need to be established along with contact details for unexpected situations. Maintenance contractors and other commercial organisations often provide such a facility, at a cost, if required. A more effective use of a Bureau Service would be to audit the BEMS performance, rather than only provide a reactive alarm monitoring function. This would require the Bureau Service to have skilled and experienced staff who could interrogate the BEMS, interpret the results and monitor that appropriate action had been taken. As such, this role would not be suitable for site security staff. Use of a Bureau Service would need to be considered in relation to the existing contractual arrangem ents to determine whether scope is available for this.

Another option would be to use the enthusiasm and expertise of existing Site Energy Managers by extending their role and responsibility across a number of sites. Depe ndent on site sizes, one Site Energy Manager could potentially have responsibility for several sites if linked through a suitable communication network. The BEMS at each location would provide local control and reporting. The Site Energy Manager would interpret the data and, from intimate knowle dge of the sites, be able to initiate the appr opriate action. This role would be further enhanced by access to a comprehensive energy M&T system.

4.2

OUTLINE SPECIFICATION FOR LEVELS OF BEMS OPERATOR

To provide a better understanding of the different potential operating roles of BEMS, the following four categories show typical aspects of various levels and typical posts in which they would be suited. Impor tant Note: Any adjustm ents, control functi on or accessibility to BEMS plant should be approved in writing by the Property Manager. This should detail the specific tasks and level of controlability to be authorised including the name(s) of the individual(s) being given the authority. These levels are generic and actual allocation of roles and responsibilities would benefit from input by experienced personnel. Level One - typically fits within the role of Energy Warden and may include/

require: •

basic understanding of BEMS purpose and method of beneficial operation

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DMG 22 Building Energy Management

Systems


•

no or very limited permission to make alterations to set points

•

ability to call-up and view data from schematics and points list

•

ability and access to view and interpret trend logs for relevant areas

•

access to pertinent limited areas of the site only.

Level Two - typically fits within the role of the Property Manager or other Managers and may include/require:

•

as Level One above but also requires access to infor matio n and data for the whole site. Not normally permitted to make alterations to set points.

Level Three - typically fits within the role of the WSM, EWC or other similar service provider organisations and may include/require:

•

a detailed understanding and knowledge of all aspects of the BEMS required

•

a detailed understan ding and knowledge of all plant integrated with the BEMS. Able to call up and view point data from schematics and points list for whole site

•

full access to all control functio ns, liaison with Site Energy Manager, advised if environmental set points or time setting to be altered

•

ability and access to acknowledge system alarm s

•

ability and access to add analogue and digital inputs and outputs to the system

•

ability and access to change control strategies

•

ability and access to view trend logs.

Level Four - typically fits within the role of the Site Energy Manager and may include/require:

•

a full understanding of the BEMS architecture, design philosophy and capabilities

•

a full unders tandin g of the functio ns of the engineering systems controlled by the BEMS

•

access and ability to call up and view point data fro m schematics and points lists for the whole site

•

access and ability to view all system data and set up trend logs or exception alarms

•

visibility of all system alarms for relay on to relevant maintena nce personnel

•

access and ability to make changes to time and occupancy controls and set points and alarms

•

ability and access to add or change graphics

•

ability to change control strategies and add analogue and digital input s and outputs to the system.

These four levels are only indicative and the particular site and its requirements will dictate those appro priate. In some instances, levels may be combined , in others, sub-levels within those shown may be created.

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4.3

TRAINING

To obtain the full benefit of a BEMS it is essential that people who are authorised to use, operate and maintain it, are trained to allow them to have a good understanding of its capabilities, purpose and potential. Such training needs to be an ongoing process.

Operators need to understand the prime function of the BEMS, which may have changed since the original design specification was produced. They also need to be trained in the operating method of the system. Problems that may arise when established procedures are not followed should be part of the training programme. The procedure for making changes, alterations or additions to the BEMS should already be defined, but will need to be explained, together with how to record system malfunctions or concerns about incorrect performance to enable them to be resolved by the maintainer. BEMS operators will need to be trained to understand the displays, how to monitor and change time schedules, set points and environmental control settings, acknowledge and cancel alarms and take action following alarm messages. They should also be able to carry out routine maintenance of the system central station hardware (eg. replace printer cartridge). Maintenance staff require training in any specialist procedures related to the specific installation. They also need to understand the generic requirements set out in the HVCA maintenance schedules for BEMS. (See Section 5.3).

4.4

COSTS OF OPERATING BEMS

These can be divided into two elements. The first is maintenance of the installed equipment. An indicative annual cost for this is some 7% of the original installed cost for the complete controls installation. However, the controls components (sensors, actuators, controllers etc.) will need to be maintained in any event. The cost of maintenance of the BEMS components (ie. control operator station and communica tions network) should be identified separately. In the absence of other info rmation , a value of 0.5% of the total installed cost could be considered. This value is included within the 7% stated above (see 5.2 Maintenance Costs). The second element is the operator cost for the system. This will depend on the role of the person acting in this capacity, and whether energy M &T is included. For BEMS operation, an indicative figure of 10% - 20% full time attendance would need to be available for this role. Should energy M&T also be included, the time proportion increases to 30% - 40%.

4.5

UPGRADING AND REFURBISHMENT OF BEMS

The cost of upgrading or refurbishment of BEMS will need to be demonstrated to be cost effective. Anticipated energy savings are likely to be the principle jus tifica tion, thou gh other p otential advantages, listed in para 1.5, may also be appropriate. A life cycle cost analysis showing anticipated operating, maintenance and repair costs of the existing equipment, compared with the cost of upgrade or refurbishment, over say 15 years, can help to ma ke the case.

At the design stage, adequate spare capacity should be provided in the system for known or anticipated system expansion. This extra capacity needs to be available at the central station, outstations and the communications network.

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Specific site requirements and known proposals should be used as the basis for expansion planning. However, in the absence of detailed information an allowance of 20% should be made in each of the component elements with potential for expansion such as the central station, outstations and communication network. If the BEMS is a modular system, it may be reasonable to provide minimal expansion capability during the initial installation and provide additional modules when required.

When upgrading an existing system, the initial consideration is likely to be to use the same equipment supplier. This should avoid problems with the communication standards protocols and interfaces between different suppliers' equipment. The age, reliability and performance of an existing system may influence the decision to continue with the same supplier. When an existing BEMS has insufficient capacity to upgrade to meet current requirements, it may be practical to retain field devices and the communication network to limit the project cost. It is possible that the existing equipment from a particular supplier may not be compatible with their current product range. BEMS equipment suppliers claim to be able to interface with the majority of competitors equipment. Careful programming of the project will be required to ensure all systems are operational during the upgrading. CIBSE have published the following economic life factors for BEMS components, which may be useful when considering upgrading or refurbishment. The specific applications and quality of maintenance will dictate the remaining life of existing comp onents.

Equipment Item

Typical Life Factors (Years)

BEMS operating system

5-10

AutoDial modem

5-10

Communication network (hardwiring)

28

25-30

Netwo rk communications services

10-15

Dam per actuato rs

10-15

Outstations

5-15

Sensors

3-10

Control valves

15-20

Control dam per s

15-20

Utility sub-metering

10-20

Electr onic contr ols

12-18

Hydraulic valve actuators

10-15

Pneumatic valve actuators

15-20

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5

BEMS Maintenance

5.1

PREAMBLE

With the increasing complexity of BEMS it is essential that their integrity (including software and applications) is checked and the requirements reviewed at regular intervals. Ignorance of a system's capabilities, coupled with poor commissioning and lack of client commitment can result in a BEMS becoming an expensive time clock. If the equipment is not correctly and fully commissioned and maintained by specialist, trained personnel and supported by the manufacturers, the benefits of the investment will be lost, energy wasted and operational costs will rise.

Where a BEMS is installed, the client should be aware of the need for continuous monitoring of performance. Switching off because of a malfunction or lack of data update can negate the considerable investment and give rise to unacceptable environmental conditions and energy wastage. Building operators with a BEMS should ensure that the operators have had appropriate training to understand the equipment and carry out routine daily and weekly maintenance tasks, such as monitoring and changing time schedules, set points, environmental control settings and simple computer hardware maintenance (eg. changing printer cartridges). Such training needs to be an ongoing process.

5.2

MAINTENANCE COSTS

It is essential to make provision for the ongoing maintenance of a BEMS once it is installed. As a budget indicator, an annual cost of 7% of the installed cost (ie. the hardware, software , outstations, sensors and actuators, and communication interfaces) should be allowed for the complete controls installation. This figure has been obtained from suppliers, BEMS specialist maintenance contractors and MOD users. This would cover, depending on the size of the installation, maintenance of the central operator station, data communications, controllers and software functions, calibration of sensors, and operational checks of actuators. Spare parts and replacements would be additional costs. As noted in para 4.4, Costs of Operating BEMS, the maintenance of the BEMS components is a small proportion of the 7% figure.

5.3

CONTRACT ARRANGEMENTS

The HVCA have produced a series of standard maintena nce specifications for mechanical services in buildings. Volume III covers Control, Energy and

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Section 5 BEMS Maintenance

Building Energy Management Systems. The HVCA Standard can be used as a means of checking that work has been carried out and conforms to the requirements. It is essential that the specialist engineer appointed for BEMS maintenance is familiar with the equipment and the manufacturer's maintenance manual. Maintenance schedule or contract needs to be in place from the date the BEMS is handed over to the client. One option for the initial twelve month period is to include the cost in the supply contract. If this is done, the cost details need to be separately identified in the tender document. Contract options are:

•

direct contract to specialist or equip ment supplier

•

arrange call-out facility only with specialist or supplier

•

place BEMS maintenance through main M&E maintenance contractor.

Details of the arrangement also need to be addressed, such as minimum call-out response time, whether a fully comprehensive contract is required (ie. costs include all spares, consumables, and replacement following breakdown). Maintenance contractors undertaking BEMS maintenance should have specialists with:

•

necessary training

•

knowledge of the installed system

•

up-to-date aware ness of manufactu rers equipment

•

access to up-to-date diagnostic equipment

•

good technical support

•

access to good stocks of spares.

5.3.1

Operating and Maintenance Documentation

It is essential that a detailed manual be kept on site. This site manual records the responsibilities of all parties involved with the BEMS, together with the installed equipment, normal settings, control diagrams and location of the Operating and Maintenance man ual relating to the specific plant and control equipment. This site manual can also serve as a service log to record faults and observed by the BEMS operator, changes to control parameters, set points, program algorithms plus reasons why the change was necessary. It can also be used to check when each entry is resolved.

5.4

SPARES AND CONSUMABLES

Investigation of typical BEMS installations at various MOD locations indicated that spares and consumables may not need to be stored on site, as they are often readily available from manufacturers and could be charged for on an 'as required' basis.

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Section 5 BEMS Maintenance

Therefore, it is not recommended that BEMS spares be held on site unless particular requirements such as equipment serving a strategically essential system justify this. Items which are known to be regularly replaced such as sensors, valves and actuators, which are common throughout the site, would justify being held at minimum levels to allow replacement to be carried out.

5.5

RECOMMISSIONING

Over time, BEMS settings, perfor manc e and operating param eters will change as items become worn, electrical items drift and other circumstances change.

Regular recommissioning of the BEMS can help ensure it is operating at its full potential, maximum energy savings are being achieved and plant performance and expected life is maximised. The frequ ency and areas of the BEMS for recommissioning should be based on regular monitoring of the BEMS performance and any major changes in the use or layout of the areas being managed by it. An indicative cost for recommissioning should be based on around 30 minutes per point to be covered.

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32

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DMG22 Building Energy Management Systems

6

6.1

Energy monitoring and targeting

REVIEW AND RELATIONSHIP WITH BEMS

A target can be defined as a meas urable objective to be achieved in a given time. In terms of energy management, it may be a forecast over a twelve month period of the expected utility consumption eg. electricity, gas, oil, water. For heating, cooling and lighting loads, there will be fluctua tions over the twelve month period due to variations in external weather conditions and the available hours of daylight. This is in addition to the specific building requirements such as changes in the hours of occupancy. Figure 4 shows an example target consumption for an office type building, with a tolerance margin around the target line of ±10% to show acceptable performance criteria.

Figure 4 Energy monitoring and targeting

7000

Target Consumption 6000

Target ±10% Actual Consumption

5000 4000 3000 2000 1000 0

By plotting the actual consumption on the target graph on say, a monthly basis, a good indication of performance against target can be obtained, as shown by the white line. As weather conditions are never the same year to year, or even month to mont h, the results m ay need to be normalised by the use of degree-day information. This provides detailed meteorological informatio n of the days when heating (or cooling) would have been required, which allows target information to be modified to actual local weather conditions.

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Section 6 Energy monitoring and targeting

An alternative method for establishing a target is to mo nitor consu mption over say, a twelve month period. Potential energy savings can then be identified and energy targets set. Comparison of actual performa nce (or the current p erform ance) against the target is called monitoring. The process of energy M&T allows regular (eg. monthly) comparisons of actual energy use to be made against plann ed or budgeted data, to identify if problems are becoming apparent. It can also allow performance of similar buildings to be analysed. Statistical data on the cumulative energy consumption figures allow trends to be obtained.

To put M&T of energy consumption into practice requires regular and reliable information to be available. One means of obtaining this data would be to read it from utility bills, another would be to physically visit local supply meters and record information. Utility bills are not always based on site visits (ie. the reading may be estimated) and the periods betwee n readings may not be consistent (eg. three weeks or five weeks for monthly readings). Use of local staff to take readings can generate inaccurate information due to difficulties or misunderstandings when reading the meter. The labour cost can also be expensive. A BEMS can provide a relatively cheap and powerful tool to obtain the energy consumption data by logging it directly from a suitable meter. This can provide a continuous information stream of very accurate data and any required time base can be used to analyse it. Analysis against local weather conditions to make degree day comparisons is also feasible by introducing suitable external sensors and software. The consumption data can be used to compare data on utility bills. Some BEMS suppliers have M&T software available which is appropriate for a limited number of metering points. If the number of metered points exceeds about 20 and detailed analysis and interpretation of the data is required, specialist software becomes more appropriate. Separate M&T software is required to analyse and report on the data available from the BEMS to use it to its maximum advantage. Considerable effort is required to interrogate large volumes of data. The software should ideally provide graphical output as shown in Fig 4 to visually demonstrate performance. Also, there should be a capability to generate exception reports so that routine analysis of the meter data is being carried out and warnings are only flagged up when the readings are outside pre-set limits, indicating a more in-depth investigation is required.

6.2

ADVANTAGES AND POTENTIAL COST SAVINGS

As identified above, by using a BEMS to interrogate and log data from utility supply meters, it becomes possible and practical to process large volumes of information. The BEMS communication system can be used to automatically collect, input and analyse inform ation fro m utility meters for an M&T System. This can provide significant resource savings where this information is currently collected and input manually. In addition the frequency of reading and hence quality of information from automated meter reading can be vastly superior to manual collection. Occasional manual reading of meters is still recommen ded to verify any spurious readings and provide confidence in the information provided.

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Once targets have been established, actual energy consumption can be economically monitor ed. The process of monitoring can highlight areas of energy waste, where savings can be made, such as inaccurate time controls needing to be re-set. The ready availability of energy consumption data can allow performance to be measured over time, producing trend logs that can be used to identify abnormal peaks or troughs in consumption. The data can also be used to compare with other published reference information. Publication of monitoring information against target can provide a usefu l focus for building occupants to concentrate attention on energy savings.

The availability of utility consumption data is a useful tool for checking utility bills. Billing inaccuracies have been highlighted by comparison with BEMS records and significant overpayments recovered after representation to the utility suppliers. Closer attention to utility use and consumption can also generate savings by analysis of the fuel supply tariff or contract, particularly if this has not been reviewed for some time. Utility monitoring can help to indicate whether there is abnormal use (eg. heavy consumption overnight when utility use should be minimal). This could suggest a leak in the supply or distribution system. It could also mean there is a fault with the meter.

Savings of between 5% and 15% of utility supply costs have been achieved by rigorous application of an M&T system due to the continuous control and management of consumption. These results only continue to be achieved by the ongoing impleme ntation of energy M&T. One featu re of many successful systems is that target performance fig ures are reviewed and tightened on an annual basis.

6.3

COST IMPLICATIONS

Software costs for energy M&T can range from £1500 to £7000, depending on the reporting and analysis capability being provided.

The hardware for this application could be the head end of the BEMS, or it may be felt appropriate to have a separate, dedicated PC to avoid losing the system monitoring capability of the BEMS head end. The processing capability required for analysing the monitoring and targeting data can also just ify a separate PC in addition to the BEMS head end machine. Suitable utility meters need to be available which will provide a pulsed signal to the BEMS. If these do not already exist there can be significant costs in their purchase and installation, together with their interconnection to the BEM S using dedicated commun ication cabling or interfacing with an existing data network. When main incoming supply meters, belonging to the supply authority, are involved there can be a cost of up to £1000 for initial provision together with an annual maintenance charge to ensure their accuracy. For larger sites, existing metering arrangements for main incoming utility meters may already be providing suitable data for detailed energy monitoring. The utility supplier or meter operator will be able to provide further details.

In addition, allowance needs to be made for customising the software to the particular application. An indicative cost for this, based on two man days work, would be £1000. January 2001

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Once the system is in place and fully operational, it needs to be administered. An indicative allowance for larger sites would be one man day per week to collate the data, interpret system reports, initiate and monitor actions, investigate queries and produce summary energy management reports.

The CIBSE Guide 'Energy Efficiency in Buildings' suggests that a manual M&T system may be suitable for a building with an energy bill less than £10,000 pa, and could cover invoice checking, monthly energy consumption plotting and comparisons with consumption in previous years. On buildings or sites with energy consumption u p to £100,000 pa, the Guide suggests a simple spreadsheet may be more appropriate for M&T. For sites and buildings with annual energy bills over £100,000 it is suggested an M&T software package may be a more appropriate approach.

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Annex A - Typical costs and savings associated with BEMS

TYPICAL COSTS AND SAVINGS ASSOCIATED WITH BEMS

Scoping study - Provides framework and Limit of Liability for an Option Study. (Completion of this table will help in assessing initial feasibility and whether to proceed to scoping study stage. Completion at Annex A will help in defining the BEMS requirements.) Staff resources to produce the specific specification. (See Paragraphs 2.5.2, 2.5.3 and Annex A.) Full Option Study - Reviews the options, including do nothing and provides recommendations and costs for the most suitable way forward. (Use this guide, Specification 47, and other extant documentation or Defence Estates to provide guidance).

Planning, installation and commissioning costs. Remember to given an allowance for the increased useful life between any new equipment against old equipment replaced as a result of BEMS installation. (See Paragraphs 2.1, 2.9 and 4.5). Additional costs for energy Monitoring and Targeting system if required. (See Section 6) Manpower saved by automated meter reading and data processing if appropriate. (See Paragraph 6.2) Annual general maintenance costs over and above those for standard controls. (See Paragraph 4.4) Resource savings through being able to do previous tasks in less time. (See Executive Summary, Paragraphs 1.3, 1.5 and 2.3) Initial training costs. (See Paragraph 4.3)

Plant and maintenance savings through greater ability to plan, manage and implement maintenance. (See Executive Summary, Paragraphs 1.3, 1.5 and 2.3) Greater flexibility and control of building services allowing proactive and greater response speed to occupants needs. (See Executive Summary, Paragraphs 1.3, 1.5 and 2.3)

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Annex A Typical costs and savings associated with BEMS

TYPICAL COSTS AND SAVINGS ASSOCIATED WITH BEMS (CONT'D)

Ongoing training costs. (See Paragraph 4.3) Standing cost from communications such as telephone line rental. (See paragraph 2.7) Software maintenance / upgrade costs. Energy savings from improved building services control. (See Paragraph 2.3) Recommissioning costs as / if required. (See Paragraph 5.5) Any additional site specific costs or savings Totals ( Note: Take costs over the life of the system)

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Annex B - Analysis of Requirements

Location(s) covered by this project. Is there an operational requirement for central monitoring or control? Is there an existing BEMS?

Is an existing communication network available? Can existing controls be operated and maintained?

Have good housekeeping measures been applied? Are building occupants satisfied with their environment? Is there an opportunity to integrate controls of different engineering services?

Has the building function changed since BEMS installed?

Is a central station(s) required? If yes, state location.

List operational plant in each building to be connected to BEMS (use Pro Forma One). State site energy management procedures. Are these to integrate with BEMS?

If yes, state how. Does energy use compare with published guidelines? Is it required to recharge building

occupants for energy? Are consumption records needed for tariff analysis? Are any locations subject to development?

If yes, is BEMS design to include the development?

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Project Ref. Prepared By

40

Date

Is a 'portable keyboard' acceptable to access BEMS?

Yes

No

Will security/reception staff operate BEMS?

Yes

No

Will dynamic display of plant and system layouts be required?

Yes

No

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PRO FORMA ONE Project

Building reference

Prepared by

Date

Operational plant to be connected to BEMS Heating plant Heating distribution Cooling plant

Monitor

Control

Operate

Energy M&T

Importance BEMS not High = 3 required Med. = 2 Low = 1

Cooling distribution Ventilation supply Ventilation extract Toilet extract Kitchen extract Car park extract

Smoke extract/ control Fume cupboard extract Fume extract Air conditioning

Air curtain

Hot and cold water services Electrical

supply Electrical distribution Standby generation UPS General lighting Emergency lighting External lighting Security/access Fire detection/ alarm Lifts/escalators Catering

Other

January 2001

41

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Annex C - Tender Summary

(Minimum breakdown of Tender Return to allow detailed analysis) Item 1

Site Investigations

2

System Design

3

Hardware

3a

Central supervisor

3b

Controllers

3c

Unitary controllers

3d

Sensors

3e

Actuators

4

Communication network

5

Software

6

Graphics

7

Installation

8

Testing

9

Commissioning

10

Training

11

Drawing and

12

Energ y monitoring and targeting

13

Twelve month maintena nce from date of handover

January 2001

Cost

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Annex C Tender Summary

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Annex D — Energy consumption benchmarks for MOD buildings

Category

Fossil fuel Electricity Total benchmark benchmark benchmark (kWh/m 2 (kWh/m 2 (kWh/m 2 /annum) /annum ) /annum) 110 95 143

31 54 60

141 149 203

133 250 360 775

27 79 150 165

160 329 510 940

Multi-occupancy accommodation

225

29

254

Workshops

175

29

204

Motor transport facilities

317

20

337

187 54

34 3

221 57

444 315 220 100 0

21 12 23 9 9

465 327 243 109

235

75

310

114 334 123

15 88 36

129 422 159

Offices

1

2

3 Sports & recreation facility

Stores/warehouses

1

2 3 4

1

2

Hangers

1

2 3 4 5

Messes with integral accommodation Training/education

1

2 3

January 2001

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45


Annex D Energy Consumption Benchmarks for MOD Buildings

Definition of Categories

(for full explanation see ENERGY CONSUMPTION GUIDE 75 - Energy use in Ministry of Defence Establishments - details on how to obtain this Guide are given in Technical Bulletin 99/27) Category

46

Offices

1 2 3

Naturally ventilated, cellular Naturally ventilated, open plan Natural/forced ventilation and some comfort cooling

Sports & recreation facility

1 2 3 4

Dry sports facility - small Dry sports facility (without pool) - large Sports facility with pool Swimming pool only (no sports hall)

Stores/warehouses

1 2

Occupied Unoccupied

Hangers

1 2 3 4 5

Heated and uninsulated Low heating and uninsulated Heated, insulated, refurbished Very low heating or store with low activity Unheated

Training/education

1 2 3

Naturally ventilated lecture rooms Forced ventilated lecture rooms Technology training facilities

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Glossary of Terms Associated with BEMS (Generally derived from BSRIA Standard Specification for BEMS)

access time Time interval between the request for information at the central station and when it is available access control Means for limiting access within security controlled area to those with authorised identification actuator A device for turning a control signal into a physical control action

adaptive control Automa tic change of control parameters to achieve optimum system performance

alarm Audible or visual indication of a dangerous or undesirable condition algorithm A finite set of well defined rules or series of instructions or procedural steps for the solution of a specific problem or control of a particular item of plant

Relating to data that consists of continuously variable quantities

boiler compensation Changing boiler operating temperature in relation to outside temperature

boost period Period immediately prior to occupancy period during which heating plant is operating at full capacity BUS Cable connected to devices such as sensors, actuators and outstations providing data communication route central station Primary point of access to the BEMS and usual point from where operation is supervised

commissioning Advancement of an installed system to full working order in accordance with the specified requirements compensator Control device which reduces heat supply as building heat load reduces, possibly in response to outside temperature configuration software Software (in the form of "building blocks") resident in an outstation which can be configured to create different control strategies control algorithm See Algorithm

control function Term describing the form of control

controller (outstation) A device to which sensors and actuators are connected which provides monitoring and/or control of the building services functions. It also has the capacity to exchange information within the system control point Pre-selected variable such

as desired internal temperature

control strategy Logical steps used to control an item of plant together with set points and operating parameters default value A reserved value or option used when no other is specified

direct digital control Term used to indicate that plant is under the direct control of software in a BEMS outstation or central station and not through the intermediary of some stand alone no nprogrammable controller distributed (or distributed intelligence control) control BEMS system where processing is carried out at controllers (or outstations) as well as the central station duty cycling Alternating sequence of plant use to rotate operating and standby plant EMC

Electro magnetic current degree day A means of comparing variations of heating requirements in different parts of the country, normally based on the daily difference in base temperature of 15.5°C and the 24 hours mean outside temperature (CIBSE Guide B.18) digital Representation of a value by discreetly variable physical quantities

energy target Desired total energy use in a building or process

feedback control Closed loop control where the control activating signal is derived from the set point and a signal indicating the current value of the controlled medium

firmware Operating parameters and characteristics of fixed components of a system set up to provide specific requirements

47


Glossary

head end See 'Central Station'

performance specification Written description of requirements for BEMS controlled plant in terms of physical behaviour or performance ie. temperature and humidity limits, zoning time control, operation of plant. It does not specify design of BEMS. Usually written by consultants

HVAC Heating, Ventilation and Air conditioning

icon Graphical symbol indicating an object on a visual display unit LAN Local Area Network - a cabling system with associated software to link a number of computer based systems allowing them to communicate load cycling Controlling plant output by fixed on and off periods of operation mimic display A screen based display representing the HVAC system in graphical format. It will usually show current values and status of plant

set point User defined value of a control parameter that an HVAC system strives to maintain software licence Any form of document or agreement which may limit the client's use of the software resident in the BEMS Specification Particular Full BEMS specification for a project comprising:

Standard Specification monitoring Process of collecting, analysing and reporting data network An electronic method connecting computers and other equipment needing to be limited for the input, output and storage data night set back Relaxation of maintained space conditions by a preset amount for the overnight period

Supplementary specification for particular BEMS Standard specification for electrical installation Standard specification for mechanical installation trend log A collection of stored data samples relating to either physical inputs or outputs, or virtual points.

Each sample is collected at a fixed time interval

outstation See "Controller"

from the previous sample collected.

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Bibliography

Standard Specifications for BEMS Application Handbook AH 1/90 Volume 1 Specification Volume 2 Guide

BSRIA1990

Library of System Control Strategies Application Guide 7/98

BSRIA1998

Commissioning BEMS - a code of practice

BSRIA1992

Application Handbook AH2/92 BEMS Performance Testing Application Guide AG 2/94

BSRIA1994

Standard Maintenance Specification for mechanical services and buildings Volume 3: Control, Energy, BEMS

HVCA1992

CIBSE Automatic Controls and their Implications for System Design

CIBSE 1985

CIBSE Commissioning Code C Automatic Control

CIBSE 1973

Specifying Building Management Systems Technical Note TIM6/98

BSRIA1998

Building Energy Management Systems HTM 2005 Vol. 1 Management Policy Vol. 2 Design Considerations Vol. 3 Validation and Verification Vol. 4 Operational Management

NHS Estates

NHS Model Engineering Specification C54 Building Energy Management Systems

NHS Estates 1996

Installation, commissioning and maintenance of fire and security systems

BSRIA1992

Application handbook AH 3/92 Pt. 1 General Pt. 2 Fire detection

Pt 3 Security systems

Installing BEMS to meet electromagnetic compatibility Building Research Establishment requirements BRE Digest 424 1997 Survey of building and energy management user perceptions

BSERT1996

Building Control and Indoor Environmental Quality - A Best Practice Guide

BSRIA1998

Technical Note TN9/98

January 2001

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Bibliography

CIBSE Guide - Energy Efficiency in Buildings

CIBSE 1998

The Future of Building Services Management and Control Systems M. D. Clapp; K. Churches

GEC Review Vol. 8 No. 219 93

Building Automation

Electrical Review Vol. 230 No. 3


Energy in Buildings & Industry,

September 1995 Building Automation

Australian Refrigeration Air Conditioning and Heating, July 1992.

Building Services Net Benefits

Electrical Review Vol. 230 No. 14

Building Management Systems Command and Control

Premises and Facilities Management March 1991

Survey of Building and Energy Management Systems Proc. CIBSE A: Building Services Engineering Research & Technology - user perceptions 17(4) 199 - 202 (1996)

CEN (European Committee for Standardisation) CEN/TC 247 Building management products and systems for HVAC applications (Draft)

January 1999

Investment appraisal and post project evaluation

JSP 41 4 Part 4 Chapter 16

MOD Guide to Investment Appraisal and Evaluation

50

Appraisal and Evaluation in Central Government

Treasury Guidance (1997)

Through Life Costing

DEO Technical Bulletin 96/04 DEO (Works) 1996

Value Engineering

DEO Technical Bulletin 96/03DEO (Works) 1996.

January 2001

Design & Maintenance Guide 22

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