Evaluating Operational Energy Performance of Buildings at the Design Stage

34 Pages·2013·0.898 MB·English

by  Cheshire, David, Menezes, Anna Carolina

Evaluating operational energy
performance of buildings at
the design stage
CIBSE TM54: 2013
The rights of publication or translation are reserved.
No part of this publication may be reproduced, stored in a retrieval system or
transmitted in any form or by any means without the prior permission of the
Institution.
© August 2013 The Chartered Institution of Building Services Engineers London
Registered charity number 278104
ISBN 978-1-906846-38-1
This document is based on the best knowledge available at the time of publication.
However no responsibility of any kind for any injury, death, loss, damage or delay
however caused resulting from the use of these recommendations can be accepted
by the Chartered Institution of Building Services Engineers, the authors or others
involved in its publication. In adopting these recommendations for use each
adopter by doing so agrees to accept full responsibility for any personal injury,
death, loss, damage or delay arising out of or in connection with their use by or on
behalf of such adopter irrespective of the cause or reason therefore and agrees to
defend, indemnify and hold harmless the Chartered Institution of Building Services
Engineers, the authors and others involved in their publication from any and all
liability arising out of or in connection with such use as aforesaid and irrespective
of any negligence on the part of those indemnified.
Layout and typesetting by AECOM
Printed in Great Britain by The Lavenham Press, Lavenham, Suffolk CO10 9RN
Cover illustration: ©ArchMan, sourced through www.shutterstock.co.uk
Note from the publisher
This publication is primarily intended to provide guidance to those responsible for
the design, installation, commissioning, operation and maintenance of building
services. It is not intended to be exhaustive or definitive and it will be necessary for
users of the guidance given to exercise their own professional judgement when
deciding whether to abide by or depart from it.
Any commercial products depicted or described within this publication are included
for the purposes of illustration only and their inclusion does not constitute
endorsement or recommendation by the Institution.
No party associated in any way with the production or distribution of this
document accepts any liability for any loss, financial or otherwise, caused directly,
or indirectly in association with the use of this document. In all cases the sole
responsibility for the estimate of energy use lies with the estimator.
Contents
Preface Overleaf
1 Introduction 1
2 Aims of this document 1
3 Scope of this document 1
4 Why estimate energy use? 1
4.1 Current situation 1
4.2 Evaluating energy use 2
5 Risks of evaluating energy use at the design stage 3
6 Principles of evaluating energy use 3
6.1 Principles of CIBSE TM22 3
6.2 Using dynamic simulation models 4
6.3 Assumptions and simplifications in models 4
6.4 Using benchmarks at early design stages 4
7 The methodology 4
7.1 Step 1: Establishing floor areas 5
7.2 Step 2: Estimating operating hours and occupancy factors 5
7.3 Step 3: Evaluating lighting energy use 6
7.4 Step 4: Evaluating energy use for lifts and escalators 7
7.5 Step 5: Evaluating energy use for small power 8
7.6 Step 6: Evaluating energy use for catering 10
7.7 Step 7: Evaluating energy use for server rooms 10
7.8 Step 8: Evaluating energy use of other equipment 12
7.9 Step 9: Evaluating energy use of domestic hot water 12
7.10 Step 10: Evaluating internal heat gains 13
7.11 Step 11: Evaluating energy use for space heating, 14
cooling, fans and pumps
7.12 Step 12: Evaluating energy use for humidification 15
and dehumidification
7.13 Step 13:Estimating management factors 15
7.14 Step 14: Running scenarios 15
7.15 Step 15: Sensitivity analysis 16
7.16 Step 16: Review against benchmarks 17
7.17 Step 17: Presenting the results 18
8 Post occupancy evaluation 19
References 19
Preface
The built environment accounts for nearly half of the UK’s carbon emissions. However the
cost of energy in buildings, as both a proportion of operating costs for a building and for the
businesses that occupy them, is very small. As a result, there has been very little focus on
delivering efficient buildings. Building engineers have been more concerned to ensure
comfort for those using the buildings. Comfort and efficiency should not be seen to be
mutually exclusive. Both can be achieved at the same time and by managing buildings
more efficiently, comfort can even be enhanced.
At British Land we have changed the way we manage our buildings, giving much greater
emphasis to efficiency, but definitely not at the expense of comfort. We actively monitor the
performance of central plant and the common parts in our buildings. This has resulted in
the last four years in a 38% reduction of energy used to provide landlord services across our
portfolio. These savings have been achieved in both old and our newest buildings alike.
This has reinforced our belief that even the newest buildings need active management to
enhance energy performance.
Research has also shown that new buildings, once operated typically consume between 50%
and 150% more energy than original expectations. This highlights that there is a real
opportunity in new buildings to align operational performance with design assumptions,
which in time will result in delivery of more efficient buildings..
This CIBSE TM is therefore very timely. It encourages building designers to consider the
implications of their design for operational energy use. It provides guidance on how to
address energy at the design stage, not just to comply with Building Regulations and EPC
ratings, but also to improve the understanding of operational energy performance. At
British Land we are adopting the principles of this guidance as we design our new buildings.
We are challenging our design teams to give greater consideration to operational performance
and how we can benchmark design assumptions with future operational performance. We
are looking to our designers to apply these guidance principles to future design work both
to improve the energy performance of our portfolio and to improve the service we can offer
our occupiers.
We believe that this focus on energy use at design will reduce the performance gap between
design and operational use in our new buildings. We think it offers the same benefits for all
others developing or refurbishing buildings.
Justin Snoxall
Head of the Business Group, British Land
Foreword
There has been a growing awareness for some time that many ‘low energy buildings’ use
more energy than the designers thought they would. As energy costs have risen, this
awareness has started to spread to building owners, who hear much about low energy
buildings and subscribe to programmes that rate the design of the building, only to find
that their ‘low energy design’ turns out to be have a typical energy bill. The performance
of low energy designs is often little better, and sometimes worse, than that of an older
building they have replaced, or supplemented.
This phenomenon is not restricted to the UK, but has been observed as far afield as the US
and Australia. There is a mismatch between the expectations around the performance of
new buildings and the reality of the utility bills. This difference between expected and
realised energy performance has come to be known as the ‘performance gap’.
There are two main reasons for this performance gap. The first is that the method of
calculating energy use for the purposes of compliance does not take into account all the
energy uses in a building. In particular, it does not address energy used by lifts and
escalators, for catering facilities, or for server rooms. This energy use can be substantial: in
one case study, the National Trust HQ at Swindon, it was found that 60% of the energy use,
that for the server room and the catering, was used in just 3% of the floor area, and more
than doubled the operational energy use over the design estimates.
The second reason for the performance gap is related to site practice. To deliver a building
that uses as much energy as expected requires that the design is built as intended, the
engineering systems are commissioned effectively and the operators and occupiers of the
building understand how to operate and maintain the building so that it delivers the
expected performance.
This Technical Memorandum (TM) addresses the first reason. It provides building
designers and owners with clear guidance on how to evaluate operational energy use more
fully, and accurately, at the design stage. After a brief introduction, which explains the need
for the guidance in more detail, it explains the importance of making an accurate estimate
of the operating hours and likely occupancy of the building. It then sets out how the
operational energy required for the building can be estimated. As well as covering lighting,
heating, ventilation and cooling and provision of hot water, it also considers lifts and
escalators, small power loads, catering, server rooms and other plant and equipment.
In each case, it provides guidance on how to make more accurate estimates based on the
intended use and operation of the building. As well as enabling the designer to estimate
energy use more accurately, it will highlight any areas where actual energy use may be
higher than a typical building, allowing this to be considered at the design stage.
This guidance will help to turn low energy designs into low energy buildings that achieve
the design energy targets. It is one of several CIBSE actions to promote more effective
assessment of energy performance. CIBSE, along with the RIBA and other partners, has
been instrumental in the development of the Carbon Buzz website, which provides a
practical tool for designers to compare their low energy designs against others on the
website, as well as providing benchmarks of expected and realised performance. Users of
this guidance will find that Carbon Buzz is based on similar principles and complements
this guidance. For more details visit www.carbonbuzz.org.
This TM seeks to provide designers with the means to better address operational energy at
the design stage. Whilst political leaders in the UK continue to debate the future electricity
supply arrangements needed to meet our future energy demands, this guidance offers
practical guidance to enable the buildings we are designing, or redesigning, to deliver the
energy performance that the owners and operators expect, and to reduce their demands for
energy in the years to come.
Hywel Davies
CIBSE Technical Director
Principal authors
David Cheshire (AECOM)
Anna Carolina Menezes (AECOM)
Contributors
Mark Bacon (AECOM)
Andrew Cripps (AECOM)
Xavier Fulbright (AECOM)
Brian Graham (AECOM)
Anna Holding (AECOM)
Martin McLaughlin (AECOM)
Ant Wilson (AECOM)
CIBSE Steering Group
David Hughes (chair)
Dave Cheshire (AECOM)
Andrew Cripps (AECOM)
Hywel Davies (CIBSE)
John Field (TEAM (EAA Ltd.))
Phil Jones (Building Energy Solutions)
Anna Carolina Menezes (AECOM)
Sanaz Nazemi (CIBSE) (secretary)
Philip Oliver (Kyoob Ltd.)
Ian Pegg (Johnson Controls)
Mike Smith (BSRIA)
John Ward (SES)
CIBSE Referees
Eszter Gulacsy (Mott MacDonald)
David Kingstone (Buro Happold)
Brian Spires
Editor
Ken Butcher
Editorial Manager
Ken Butcher
CIBSE Technical Director
Hywel Davies
CIBSE Head of Knowledge
Nicolas Peake
1
Evaluating operational energy performance
of buildings at the design stage
1 Introduction — allow designers and prospective occupiers to
understand where and how energy is likely to be
used in the building
Construction clients, particularly owner-occupiers, are
becoming increasingly interested in the operational energy — allow designers to understand which measures have
performance of the buildings that they procure. This can the greatest impact on energy use
lead to targets being set in the project brief to achieve
— ensure that prospective occupiers do not have
energy performance in line with the design estimates.
unrealistic expectations about the performance of
their new building.
As a result, building services engineers and low carbon
consultants are being asked to provide estimates of the
likely operational energy performance of buildings at the 4.1 Current situation
design stage.
In the UK, energy models are used at the design stage to
This document aims to help building services engineers to compare design options and to check compliance with
respond to this request in a robust way. Building Regulations. These energy models are not
intended as predictions of energy use, but are sometimes
mistakenly used as such.
2 Aims of this document
In some other countries, total energy use at the design stage
is estimated through voluntary standards. For example, the
The aims of this document are to: Australian NABERS (a building rating system) encourages
the estimation of energy use at the design stage and provides
— help engineers respond to a project brief where an
guidance for designers/modellers (NSW, 2008). Similarly,
operational energy target has been set
ASHRAE 90.1 (ASHRAE, 2007) provides guidance for
— provide a methodology that engineers can use to energy modellers on estimating energy use at the design
undertake better-informed calculations of energy stage.
use in operation
Figure 1 shows a comparison for a case study building (see
— demonstrate that energy performance is dependent Box 2), broken down into the various end-uses. This
on how the building is run and maintained, as well comparison shows the results from Building Regulations
as how it is designed and constructed.
Part L model versus actual energy use
3 Scope of this document 350
Lifts
This document is written mainly for engineers and Servers
300
consultants working in the UK. The methodology can be
Catering
applied to other countries, with the appropriate adjustments 2m) electricity
to the references, benchmarks etc. Wh/ 250 Office
k equipment
Twohrek emd eetxhaomdoplloe giyn tihsi sf doro cunmone-ndto ims efostri ca n bouffiilcdei nbgusi.l dTinhge, on / ( 200 Lighting
but the methodology can be applied to other types of mpti Fans, pumps,
buildings. su 150 controls
n
o
c Cooling
al
u 100
n Hot water
4 Why estimate energy use? An (gas)
Heating
50
(gas)
Providing estimates of energy use at the design stage can:
— supply prospective occupiers with a clearer 0
indication of the likely range of energy use, carbon Part L model Actual
dioxide emissions and costs of running their new Figure 1 Comparison of ADL2A calculations and operational performance
building for a case study
1
Evaluating operational energy performance
of buildings at the design stage
1 Introduction — allow designers and prospective occupiers to
understand where and how energy is likely to be
used in the building
Construction clients, particularly owner-occupiers, are
becoming increasingly interested in the operational energy — allow designers to understand which measures have
performance of the buildings that they procure. This can the greatest impact on energy use
lead to targets being set in the project brief to achieve
— ensure that prospective occupiers do not have
energy performance in line with the design estimates.
unrealistic expectations about the performance of
their new building.
As a result, building services engineers and low carbon
consultants are being asked to provide estimates of the
likely operational energy performance of buildings at the 4.1 Current situation
design stage.
In the UK, energy models are used at the design stage to
This document aims to help building services engineers to compare design options and to check compliance with
respond to this request in a robust way. Building Regulations. These energy models are not
intended as predictions of energy use, but are sometimes
mistakenly used as such.
2 Aims of this document
In some other countries, total energy use at the design stage
is estimated through voluntary standards. For example, the
The aims of this document are to: Australian NABERS (a building rating system) encourages
the estimation of energy use at the design stage and provides
— help engineers respond to a project brief where an
guidance for designers/modellers (NSW, 2008). Similarly,
operational energy target has been set
ASHRAE 90.1 (ASHRAE, 2007) provides guidance for
— provide a methodology that engineers can use to energy modellers on estimating energy use at the design
undertake better-informed calculations of energy stage.
use in operation
Figure 1 shows a comparison for a case study building (see
— demonstrate that energy performance is dependent Box 2), broken down into the various end-uses. This
on how the building is run and maintained, as well comparison shows the results from Building Regulations
as how it is designed and constructed.
Part L model versus actual energy use
3 Scope of this document 350
Lifts
This document is written mainly for engineers and Servers
300
consultants working in the UK. The methodology can be
Catering
applied to other countries, with the appropriate adjustments 2m) electricity
to the references, benchmarks etc. Wh/ 250 Office
k equipment
Twohrek emd eetxhaomdoplloe giyn tihsi sf doro cunmone-ndto ims efostri ca n bouffiilcdei nbgusi.l dTinhge, on / ( 200 Lighting
but the methodology can be applied to other types of mpti Fans, pumps,
buildings. su 150 controls
n
o
c Cooling
al
u 100
n Hot water
4 Why estimate energy use? An (gas)
Heating
50
(gas)
Providing estimates of energy use at the design stage can:
— supply prospective occupiers with a clearer 0
indication of the likely range of energy use, carbon Part L model Actual
dioxide emissions and costs of running their new Figure 1 Comparison of ADL2A calculations and operational performance
building for a case study
1
Evaluating operational energy performance
of buildings at the design stage
1 Introduction — allow designers and prospective occupiers to
understand where and how energy is likely to be
used in the building
Construction clients, particularly owner-occupiers, are
becoming increasingly interested in the operational energy — allow designers to understand which measures have
performance of the buildings that they procure. This can the greatest impact on energy use
lead to targets being set in the project brief to achieve
— ensure that prospective occupiers do not have
energy performance in line with the design estimates.
unrealistic expectations about the performance of
their new building.
As a result, building services engineers and low carbon
consultants are being asked to provide estimates of the
likely operational energy performance of buildings at the 4.1 Current situation
design stage.
In the UK, energy models are used at the design stage to
This document aims to help building services engineers to compare design options and to check compliance with
respond to this request in a robust way. Building Regulations. These energy models are not
intended as predictions of energy use, but are sometimes
mistakenly used as such.
2 Aims of this document
In some other countries, total energy use at the design stage
is estimated through voluntary standards. For example, the
The aims of this document are to: Australian NABERS (a building rating system) encourages
the estimation of energy use at the design stage and provides
— help engineers respond to a project brief where an
guidance for designers/modellers (NSW, 2008). Similarly,
operational energy target has been set
ASHRAE 90.1 (ASHRAE, 2007) provides guidance for
— provide a methodology that engineers can use to energy modellers on estimating energy use at the design
undertake better-informed calculations of energy stage.
use in operation
Figure 1 shows a comparison for a case study building (see
— demonstrate that energy performance is dependent Box 2), broken down into the various end-uses. This
on how the building is run and maintained, as well comparison shows the results from Building Regulations
as how it is designed and constructed.
Part L model versus actual energy use
3 Scope of this document 350
Lifts
This document is written mainly for engineers and Servers
300
consultants working in the UK. The methodology can be
Catering
applied to other countries, with the appropriate adjustments 2m) electricity
to the references, benchmarks etc. Wh/ 250 Office
k equipment
Twohrek emd eetxhaomdoplloe giyn tihsi sf doro cunmone-ndto ims efostri ca n bouffiilcdei nbgusi.l dTinhge, on / ( 200 Lighting
but the methodology can be applied to other types of mpti Fans, pumps,
buildings. su 150 controls
n
o
c Cooling
al
u 100
n Hot water
4 Why estimate energy use? An (gas)
Heating
50
(gas)
Providing estimates of energy use at the design stage can:
— supply prospective occupiers with a clearer 0
indication of the likely range of energy use, carbon Part L model Actual
dioxide emissions and costs of running their new Figure 1 Comparison of ADL2A calculations and operational performance
building for a case study
1
Evaluating operational energy performance
of buildings at the design stage
1 Introduction — allow designers and prospective occupiers to
understand where and how energy is likely to be
used in the building
Construction clients, particularly owner-occupiers, are
becoming increasingly interested in the operational energy — allow designers to understand which measures have
performance of the buildings that they procure. This can the greatest impact on energy use
lead to targets being set in the project brief to achieve
— ensure that prospective occupiers do not have
energy performance in line with the design estimates.
unrealistic expectations about the performance of
their new building.
As a result, building services engineers and low carbon
consultants are being asked to provide estimates of the
likely operational energy performance of buildings at the 4.1 Current situation
design stage.
In the UK, energy models are used at the design stage to
This document aims to help building services engineers to compare design options and to check compliance with
respond to this request in a robust way. Building Regulations. These energy models are not
intended as predictions of energy use, but are sometimes
mistakenly used as such.
2 Aims of this document
In some other countries, total energy use at the design stage
is estimated through voluntary standards. For example, the
The aims of this document are to: Australian NABERS (a building rating system) encourages
the estimation of energy use at the design stage and provides
— help engineers respond to a project brief where an
guidance for designers/modellers (NSW, 2008). Similarly,
operational energy target has been set
ASHRAE 90.1 (ASHRAE, 2007) provides guidance for
— provide a methodology that engineers can use to energy modellers on estimating energy use at the design
undertake better-informed calculations of energy stage.
use in operation
Figure 1 shows a comparison for a case study building (see
— demonstrate that energy performance is dependent Box 2), broken down into the various end-uses. This
on how the building is run and maintained, as well comparison shows the results from Building Regulations
as how it is designed and constructed.
Part L model versus actual energy use
3 Scope of this document 350
Lifts
This document is written mainly for engineers and Servers
300
consultants working in the UK. The methodology can be
Catering
applied to other countries, with the appropriate adjustments 2m) electricity
to the references, benchmarks etc. Wh/ 250 Office
k equipment
Twohrek emd eetxhaomdoplloe giyn tihsi sf doro cunmone-ndto ims efostri ca n bouffiilcdei nbgusi.l dTinhge, on / ( 200 Lighting
but the methodology can be applied to other types of mpti Fans, pumps,
buildings. su 150 controls
n
o
c Cooling
al
u 100
n Hot water
4 Why estimate energy use? An (gas)
Heating
50
(gas)
Providing estimates of energy use at the design stage can:
— supply prospective occupiers with a clearer 0
indication of the likely range of energy use, carbon Part L model Actual
dioxide emissions and costs of running their new Figure 1 Comparison of ADL2A calculations and operational performance
building for a case study