Building environmental assessment methods: Applications and development trends

Abstract

The construction and property sector has seen the development of a number of methods for evaluating the ‘greenness’ of buildings in the 1990s - both for new designs and existing buildings. These range from very detailed life cycle assessment methods, which account for all the embodied and operational environmental impacts of building materials, to higher level environmental impact assessment methods, which evaluate the broader implications of the building's impact on the environment. In between these two are environmental assessment methods such as BREEAM, BEPAC, LEED, and GBA. In this paper, we discuss the potential market applications of these systems and compare and contrast several of the major environmental assessment methods.

Full text

Building environmental assessment methods:
applications and development trends
Drury Crawley1and Ilari Aho2
1US Department of Energy, 1000 Independence Avenue, SW, Washington, DC 20585-0121, USA
E-mail: drury.crawley@ee.doe.gov
2Motiva, PO Box 462, FIN-02151 Espoo, Finland
E-mail: ilari.aho@motiva.
The construction and property sector has seen the development of a number of methods for evaluating the
‘greenness’ of buildings in the 1990s – both for new designs and existin g buildings. These range from
very detailed life cycle assessment methods, which account for all the embodied and operational
environmental impacts of building materials, to higher level environmental impact assessment methods,
which evaluate the broader implication s of the building’s impact on the environment. In between these
two are environmental assessment methods such as BREEAM, BEPAC, LEED, and GBA. In this paper, we
discuss the potential market applications of these systems and compare and contrast several of the major
environmental assessment methods.
Le secteur de la construction et de l’immobilier a e
Âte
Âle te
Âmoin du de
Âveloppement d’un certain nombre de
me
Âthodes permettant d’e
Âvaluer les performances e
Âcologiques des ba
Ãtiments dans les anne
Âes 1990, tant sur le
plan des nouveaux concepts que des ba
Ãtiments existants. Ces me
Âthodes vont de l’e
Âvaluation tre
Ás de
Âtaile
Âe du
cycle de vie, qui tient compte de l’impact spe
Âci® que et des incidences ope
Ârationnelles des mate
Âriaux de
construction sur l’environnement, jusqu’a
Áune e
Âvaluation de l’impact environnemental a
Áun niveau plus e
Âleve
Â.
Entre ces de ux extre
Ãmes, on trouve des me
Âthodes d’e
Âvaluation environnementale telles que BREEAM, BEPAC,
LEED et GBA. Dans cet article, nous examinons les applications commerciales potentielles des ces syste
Ámes;
nous comparons, en les opposant, plusieurs me
Âthodes majeures d’e
Âvaluation environnementale.
Keywords: environmental assessment, green buildings, life cycle assessment, building performance, Green
Building Challenge
Introduction
Throughout the world economy, many industrial
sectors are beginning to recognize the impacts of
their activities on the environment and to make
signi® cant changes to mitigate their environmen-
tal impact. The construction and property sector is
also starting to acknowledge their responsibilities
for the environment ± causing a shift in how
buildings are designed, built, and operated. This
shift in attitude comes from conscious public
policy decisions imposing requireme nts on indus-
trial and economic activities but also from a
growing market de mand for environmentally
sound products and services.
A central issue in striving towards reduced
environmental impact is the need for a practicable
and meaningful yardstick for measuring environ-
mental performance, both in terms of identifying
starting points and monitoring progress. As for
any other sector, from the construction and
property sector’s perspective this can be divided
in two slightly different points of view: measuring
the environmental impact of design, construction
and property management activities (as services
or industrial production processes) and the
environmental impact of buildings (as products).
From the latter point of view the question is about
identifying and quantifying of the environmental
impact of the construction, use and eventual
0961–3218 #1999 E & FN Spon
300 Bu i l d i n g Re s e a r c h & I n f o r m a t i o n (1999) 27 (4/5), 300–308

dismantling of a building in a given location and
time span.
Two basic methodological frameworks have been
developed for assessing the environmental impact
of a given object: Environmental Impact Assess-
ment (EIA) and Life Cycle Assessment (LCA). In
principle both share the aim of objectively inven-
torying and assessing the environmental impacts of
their objects of study, but they differ in one
fundamental sense (Fig. 1). In EIA the focus is put
on assessing the actual environmental impacts of an
object located on a given site and in a given context,
whereas LCA is formulated to assess the non-site
speci® c potential environmental impacts of a
product regardless of where, when or by whom it
is used.
Thinking about a building as a product, as an object
of environmental performance assessment, it be-
comes clear that buildings fall some where in
between the strict scopes of EIA and LCA. Build-
ings incorporate a variety of characteristics of an
inherently site and context depende nt nature,
making buildings from this perspective natural
objects for an EIA study. Among the most obvious
examples of such characteristics are choices of
energy carriers (often at least partly dictated by
locally available infrastructure), induced transport
requirements to and from the site, buildings’
impacts on surrounding properties etc. On the
other hand buildings ± e ven though extremely
complex in comparison with many others ± can be
also conside red as generic industrial products
serving a well de® ned functional need over a
de® nable life cycle, thus ® tting also into the scope
of LCA. Hence most of the currently applied
building environmental assessment methods ±
discussed in more detail later ± are in a sense
crossbreeds of the two approaches (Bryan, 1998).
Applications for environmental
assessment in the building sector
Environmental management systems in the
real property sector
The introduction of environmental management
systems, in compliance with the ISO 14000 series
standards or the EMAS scheme within the Eur-
opean Union, is also gradually taking place in the
property sector. Establishing an environmental
management system aims to change an organiza-
tion’s management practices and operational pat-
terns in order to reach improvements in the
environmental performance and, consequently, in
the long term business performance of the organi-
zation.
Among the ® rst steps in establishing an environ-
mental management system (both in terms of ISO
14000 and EMAS) is the conduction of an environ-
mental review of the company’s activities and
processes. From a property company’s (be it a
developer, property holding company, institutional
building owner, etc.) perspective it is (or at least
should be) obvious that a major contribution to the
company’ s total environmental impact comes from
the construction, operation and maintenance of the
buildings and facilities the company provides to its
customers. Hence an environmental state-of-the-art
review of a property company should build on an
analysis of the company’s property portfolio.
Environmental Impact Assessment (EIA)
site and context specific actual impa cts
on the environm ent
applied on large capital stock
investments, infrastructure projects etc
·
·
Life Cycle Assessment (LCA)
non site specific pot ential impacts on
the environm ent
standardized principles (ISO 1404x)
applied on the product level
·
·
·
Community
Buildings
Building products and components
Construction materials
Fig. 1. Conceptual differences between environmental impact assessment (EIA) and life cycle assessment (LCA).
301
BUILT ENVIRONMENTAL ASSESSMENT METHODS

Building environme ntal assessment methods, if
properly formulated and implemented, provide a
good set of tools for this purpose.
As the information produced by such a review is (in
theory) only intended to serve the property
company’s efforts in producing plans and pro-
grammes for reducing environmental impact, the
methods and tools used do not need to be either
standardized nor transparent. From this point of
view the only actual requirements on the content of
the applied environmental assessment methods are
de® ned by the amount, type and quality of
information needed to serve the company’s speci® c
internal targets.
Public instruments for property marketing
The primary intention behind the development of
schemes for environmental labelling, rating and
declaration of products is to provide consumers
with the means for making purchase decisions
based on the environmental characteristics of
available product alternatives. Industrial and com-
mercial faith (at least in certain sectors) in the
market transformation impacts of such schemes is
visualized in the fact that there is already a large
number of variable sche mes existing, developed
either for different kinds of consumer product
groups or for assessing products from different
standpoints.
The main difference between the different ap-
proaches can be found in the amount of informa-
tion directly provided to the consumer and in the
level of aggregation of this information. Whereas
environmental labelling only declares that a pro-
duct meets certain prede® ned environmental re-
quirements, the idea behind rating systems is to
inform the consumer also on the product’s per-
formance relative to available alternatives. Envir-
onmental product declarations, on the other hand,
provide a structured account on a product’s
`environmental content’, but usually do not allow
direct comparisons between products because of
the disaggregated nature of the information pro-
vided.
Building environme ntal assessment methods can in
principle be envisaged to apply for all three
purposes. (In practice, however, the usefulness to
the average consumer of an environmental product
declaration of a building might in all its complexity
be questioned.) Building environmental labelling or
rating schemes exist in a number of countries
already or are being developed. Most common
examples of such schemes are, of course, BREEAM
in the UK and LEED in the US.
In order for an environmental assessme nt method
to form an acceptable basis for a public labelling or
rating scheme certain fundamental requirements
must be met, both from a philosophical and a
practical point of view.
Methodological transparency is one of the most
fundamental requirements. Both consumers and
companies operating on the market must be able to
access and understand the assumptions, data and
other me thodological issues in¯ uencing the out-
come of assessments and consequent ratings of
different buildings. This is a key issue both in terms
of the consumers making conscious choices and
meaningful comparisons and in terms of building
sector companies being able to improve their
performance and thus effectively compete on the
market.
Another important requirement, somewhat related
to the above, is that assessments leading to a public
rating should in principle be fully performance-
based and that they should not include feature-
based judgements of the building’s technical
characteristics. Rating or labelling buildings on
the basis of their technical features (e.g. envelope U-
values, inclusion of low ¯ ow sanitary ® xtures,
inclusion=exclusion of prede® ned materials, etc.)
might ® rst of all exclude buildings with certain
technical details from obtaining a good rating
regardless of the building’s overall performance.
Secondly, and more importantly, feature-based
assessment inevitably e ncourages the building
sector towards `feature-based design and mainte-
nance’ of buildings and not towards achieving
good performance, a fact which obviously is a
major contradiction with the fundame ntal targets of
building labelling and rating. In practice, however,
tools and methods available for the assessment of
many key aspects of building performance (e.g.
indoor climate) are currently not developed to the
extent that would enable practical, strictly perform-
ance based assessments to be made.
Building performance specication and
targeting
One of the most natural applications of environ-
mental assessment methods is the speci® cation of
302
CRAWLEY AND AHO

environmental targets for a construction project.
However, in addition to having a framework
provided by an environmental assessment system,
meaningful performance speci® cation also re-
quires a set of benchmarks against which targets
are set and ef® cient tools adapted for the clients’
use for verifying the proposed design’s com-
pliance with the targets. Applying the current
environmental assessment methods typically re-
quires special `environmental assessment exper-
tise’, and hence are applicable as speci® cation and
targeting tools only in larger projects where ex-
ternal expertise can be afforded.
The GBA system developed in conjunction with the
Green Building Challenge process (described in
more detail below) has to a certain extent tried to
address this problem by incorporating a `nesting
principle’ in its structure. The idea of nesting is to
allow the system to be used consistently on differ-
ent levels of de tail, e.g. to be able to assess (or set
targets for) energy consumption either on the level
of statistically or otherwise derived indicator
values, on the level of simulated energy perform-
ance predictions for the operations phase or
ultimately on the level of full life cycle energy
analysis (including cradle-to-grave or lust-to-dust
calculations of all building elements and materials,
construction site energy consumption). Hence
nesting would allow for performance targets to be
speci® ed on the highe st abstraction level and the
compliance of designs with the targets to be
veri® e d using methods indicated on the highest
level of detail. However, nesting as implemented in
GBA needs further development before it serves
this purpose in a practicable way.
Building design
Even though environmental assessme nt methods
are not originally intended to serve as design
guidelines it seems that they, in the absence of
better alternatives, are increasingly being used as
such.
However, it is important to conceptually separate
product design and product assessment. Building
design (and systems design in general) is a top-
down process in which the original overall concept
is being gradually worked towards detailed im-
plementation (Fig 2). Performance assessme nt, on
the other hand, takes place in a bottom-up direc-
tion, synthesizing the overall environmental per-
formance of a given design starting from
information on and characteristics of the technical
details of the system.
How can environmental assessment methods help
in design? The primary bene® t from these schemes
is that they can provide a structured means of
incorporating performance targets and criteria into
the design process. An example of this is the
nesting principle in the GBA method, already
discussed above, which (at least in principle)
enables overall criteria to be de® ned and evaluated
during the `design-assessment’ process (Fig 2).
Design guidelines are of a different nature. The
purpose of these is (or should be) to provide
(technical) guidance on the interrelationship be-
tween technical implementation and performance,
e.g., what are the impacts of a technical solution on
a performance indicator, how to design and
dimension a system to reach a given performance
level, etc. Hence the common denominator of
design guidelines and performance assessment
systems is materialized in performance indicators
or criteria. For building design these represent
targets, objectives and=or requirements, whereas
for performance assessment they represent the
basic output of analysis.
Performance based building codes
Development of building codes and regulations
has in many countries been directed from feature-
based towards performance-based requirements.
This is especially the case for building energy
codes for which the change is visualized by a shift
from regulations concerning, for example, maxi-
mum allowable U-values of individual envelope
components to regulations on the calculated en-
ergy performance of the design. Environmental
assessment methods might provide a means for
incorporating holistic environmental performance
requirements in national building regulations, and
thus signi® cantly reducing the environmental im-
pact of new construction.
Verifying the compliance of building designs with
the magnitude of existing regulations and norms is
a time and labour consuming task, both in terms of
the designers producing necessary docume ntation
± energy and environmental regulations require
documentation beyond what is needed for actual
construction ± and in terms of local and regional
of® cials carrying out the actual compliance veri® -
cation. With design budgets already constrained,
303
BUILT ENVIRONMENTAL ASSESSMENT METHODS

construction clients and their designers might not
welcome the extra cost of documenting the buil-
ding’ s environmental performance for regulatory
purposes.
Some countries have already taken steps towards
accepting environmental assessment as an alter-
native route to complying with building regula-
tions. One of the ® rst examples is presented in the
current Norwegian building code where com-
pliance with energy performance requirements
can be shown not only by using prede® ned
envelope insulation levels or providing a calculated
energy consumption, but also by performing a
(more or less detailed) LCA study on the building
and comparing the results with the life cycle energy
use of a `standard building’. This, of course,
provides a host of new opportunities and degrees
of freedom for building design, possibilities which
can be used to compensate for the additional cost of
carrying out detailed assessments during the
project. This could provide an additional incentive
for construction clients to take on environmental
assessment as standard practice in construction
projects.
However, it should be noticed that a considerable
amount of education and training is needed both on
the local and regional authorities’ side and on the
design professionals’ side before mandatory instru-
ments can effectively operate on the market. The
transition from traditional feature based building
codes to performance requirements has already, in
the case of energy regulations, turned out to be a
large step for both professions.
Environmental auditing of existing buildings
The vast majority of the building stock was built
in the past and has been in use for several
decades, especially in Europe. The focus of con-
struction activities has gradually been shifting
from new construction to renovation and refur-
bishment projects. Also the fact that building
stocks in general are renewed at a rate of 1± 2%
annually implies that the largest improvement
potential in the environmental performance of
buildings lies in incorporating effective environ-
mental measures in renovations.
Environmental assessment methods in general, and
Users’ needs
Functional
requirements
Functions
and operating
principles
Technical
implementation
DETAILEDHOLISTIC
CONCRETE ABSTRACT
SYSTEMS DESIGN
PERFORMANCE ASSESSMENT
Operational
Environment
System
Module
Component
Basic
Characteristics
Internal
Properties
External
Qualities
General
Objectives
Fig. 2. The interrelationship and conceptual differences of systems design and performance assessment.
304
CRAWLEY AND AHO

the `building inventory’ components contained
therein in particular, provide a good starting point
for renovation and refurbishment design. Assess-
ment methods can be used both in identifying the
most critical components of the environmental
performance of existing buildings, in analysing
the potential impact of different renovation alter-
natives and in selecting and implementing the most
cost ef® cient measures for environmental improve-
ments.
Examples of existing assessment
methods
Many of the e xisting building environmental as-
sessment methods can meet some of the needs
addressed in the prior section. In this section, we
compare and contrast the appropriate applications
and scope of assessment for the four most widely
known assessment methods. The scope and appli-
cation of the assessment methods varies widely;
each assessment method is described brie¯ y be-
low.
BREEAM, Building Research Establishment
Building Research Establishment Environmental
Assessment Methodology (BREEAM) was devel-
oped by the Building Research Establishment in
the UK and is most widely used of the methods
described here. A voluntary, consensus-based,
market-focused assessment method, BREEAM
uses three scales for environmental impact: global,
local, and indoor issues (Prior, 1993). When a
building has been evaluated using BREEAM, the
result is a single score. Versions of BREEAM have
been developed for new and existing buildings in
the UK and versions have been or are being
developed for Hong Kong, Australia, and Canada.
BEPAC, University of British Columbia
Building Environmental Performance Assessment
Criteria (BEPAC) was developed at the University
of British Columbia and launched in 1993 (Cole et
al., 1993). Similar to BREEAM, BEPAC can be
used to evaluate the environmental performance
of new de signs and existing buildings. BEPAC
results in a composite weighting of ® ve major
areas: ozone protection, environmental impacts of
energy use, indoor environmental quality, re-
source conservation, and site and transportation.
BEPAC is primarily used in Canada.
LEED, US Green Building Council
Leadership in Energy and Environmental Design
(LEED) (USGBC, 1998) was developed through
consensus of the US Green Building Council. It
will be launched in a pilot programme in 1999 in
the US as a voluntary, market-based assessment
method intended to de® ne a ’green building.’ In
evaluating a building using the LEED criteria,
there are minimum, mandatory requirements in
areas such as building commissioning, energy
ef® ciency, indoor air quality, ozone de ple-
tion=CFCs, smoking ban, comfort, and water.
Once the mandatory requirements are met, a
building can earn `credits’ in 14 areas. Depending
on the total credits, a building receives a rating
level of `bronze’, `silver’ , `gold’, or `platinum’.
GBA, Natural Resources Canada and
University of British Columbia
The Green Building Assessme nt (GBA) framework
(Larsson and Cole, 1998) was developed to pro-
vide a new, common assessme nt method for
evaluating green buildings throughout the world.
Thirteen countries used the GBA to compare the
environmental features of their `best’ green build-
ings culminating in the Green Building Challenge
’98 (GBC ’98) conference held in Vancouver in
October 1998 (NRC, 1998). Building on the Cana-
dian experience with BEPAC, an international
framework committee (IFC) comprising represen-
tatives of 13 countries reviewed and developed
the GBA. The IFC worked to ensure that the GBA
took a comprehensive view of environme ntal
issues within buildings, organizing the assessment
in six major areas: resource consumption, environ-
mental loadings, quality of indoor environment,
longevity, process, and contextual factors. Further,
as described earlier, the GBA used a nesting
structure (criteria and subcriteria) to accommo-
date the large variation in information and detail
available on buildings (Cole and Larsson, 1998).
The GBA was implemented in a software tool ±
the Green Building Tool or GBTool. Data at the
individual subcriteria level were compiled in the
GBTool for the 34 buildings evaluated for GBC ’98.
Each national team developed weighting for sub-
criteria and criteria, which were applied and
composite, weighted scores for the six criteria
presented. One of the weaknesses of the GBA is
that individual country teams established scoring
weights subjectively when evaluating their build-
305
BUILT ENVIRONMENTAL ASSESSMENT METHODS

ings. Most users found the GBTool dif® cult to use
because of the complexity of the framework. We
anticipate that these perceived weaknesses will be
addressed in adjusting the GBA for use in GBC
2000.
Applications and scope
In Table 1, the potential applications described in
the previous Section ± Applications for environ-
mental assessment in the building sector ± are
used to contrast these four assessment methods ±
BREEAM, BEPAC, LEED, and GBA. These are
based upon our experience using the four assess-
ment methods. As can be seen in the table, most
methods do not meet all the identi® ed application
needs for building environme ntal assessme nt
although GBA comes closest. As found while
assessing the 34 buildings for GBC ’98, determin-
ing embodied energy was extremely dif® cult and
costly. Several countries decided speci® cally not
to address it in their assessment.
In Table 2, the outline of the GBA method is used
(resource consumption, environme ntal loadings,
indoor environment, longevity, process, and con-
textual factors) to further compare the same four
assessment methods. The scopes noted in Table 2
are based with our experience using each of the
methods. It is interesting to note that all four
methods effectively deal with resource consump-
tion issues. Beyond consumption, they vary in
focus and hence, in scope and potential applic-
ability.
Conclusions
Signi® cant advances in environme ntal assessment
methods have been seen in the last ten years.
However, signi® cant work also remains for tools
to support environmental assessment methods.
Existing (and developing) LCA tools and EIA
tools must work better with the assessment meth-
ods.
International work to develop common assessment
methods such as the GBA have revealed many
common theme s, even if the relative weighting
differ signi® cantly from country to country. These
methods can be successfully applied at the local,
regional, national, and international level through
local weighting of the issues the c riteria repre sent. In
the end, the combination of these localized weight-
ings to all the environmental issues facing the
construction and property sector become that
community or country’s valuing of what a green
building truly is .Much works remains to e nsure that
methods provide an objective means of assessing the
environmental performance of new building de-
signs and existing building re® t potentials. As the
GBA is adapted for use in GBC 2000 and beyond, it
may be adapted to ensure objectivity.
We see the following four major development paths
as vitally important for environmental assessment
of buildings:
·Methodological development should be direc-
ted to address both the assessment of buildings
(product assessme nt) and the assessment of
property=construction companies (business
process assessment). The ® rst of these ap-
proaches is serving the purposes described in
this paper. The second line of development ±
only brie¯ y touched upon in this paper and
even less in actual R&D ± would serve the
purposes of environmental management (busi-
ness process de velopment). Issues that should
be addressed include business process model-
ling from the environmental point of view,
de® ning e nvironmental ef® ciency indicators
and development of environmental accounting
in the real property sector.
Table 1. Applications of environmental assessment methods
Assessment
method
Application
Environmental
management
Product
marketing
Building
performance
targeting
Design
guidelines
Performance-
based codes
Environmental
auditing in existing
buildings
BREEAM X X X X
BEPAC X X X X
LEED X X X
GBA X X X X X X
306
CRAWLEY AND AHO

·Full consistency between materials LCA,
building products LCA and building assess-
ment should be assured through combined
effort of the research communities involved in
these ® elds. Current (and most likely also
future) building assessment methods rely more
or less blindly on the results of full LCA studies
on building materials and components, which
naturally means that con® dence in the appli-
cability of such results must be extremely
high.
·Design guidelines for green buildings are
clearly needed in the market. The fact that the
demand for guidelines for the design of green
buildings has not yet been met in a satisfactory
manner has resulted in many of the current
assessment methods, such as BREEAM, being
used in practice as de sign guidelines.
·There is a clear need for new developme nt
methods for `community assessment’. Incor-
porating community related issues (e.g. trans-
port implications) into building assessment
schemes has proven to be problematic both
from the theoretical point of view and practice,
and might even in some cases lead to wrong
conclusions.
References
Bryan, H. (1998) Ef® cacy of e nvironmental assessment
systems in addressing energy concerns, in Con-
ference Proceedings of the 23rd National Passive Solar
Conference, June, Albuquerque, New Mexico, USA,
pp. 305± 311.
Cole, R.J., Rousseau, D. and Theaker, I.T. (1993)
Building Environmental Performance Assessment Cri-
teria: Version 1 – Of ce Buildings, December. The
BEPAC Foundation, Vancouver, Canada.
Cole, R. J. and Larsson, N. K. (1998) GBC ’98 Assessment
Manual: Volume 1, Overview, April. Natural Re-
sources Canada Ottawa, Canada.
Larsson, N. K. and Cole, R. J. (1998) GBC ’98: context,
history and structure, in Conference Proceedings,
Green Building Challenge ’98. October. Vancouver,
Canada. Natural Resources Canada, Ottawa, Cana-
da, pp. 15± 25.
Table 2. Scope of environmental assessment methods
Scope Assessment method
BREEAM BEPAC LEED GBA
Resource consumption
Embodied energy X X X
Operation e nergy X X X X
Land X X X
Water X X X X
Materials X X X X
Environmental loading
Airborne emissions X X X
Solid X X X X
Liquid waste X X
Other loadings X
Indoor environment
Air quality X X X X
Thermal q uality X X X X
Visual quality X X
Noise and acoustics X
Controllability of systems X
Longevity
Adaptability X
Maintenance of performance X X
Process
Design and construction X X
Building operation X X X
Contextual factors
Contextual factors X
Loads on immediate surroundings X X X
307
BUILT ENVIRONMENTAL ASSESSMENT METHODS

Natural Resources Canada (1998) Conference Proceedings,
Green Building Challenge ’98. October. Vancouver,
Canada Natural Resources Canada, Ottawa, Canada.
Prior, J. (ed.) (1993) Building Research Establishment
Environmental Assessment Method (BREEAM), Ver-
sion 1=93. New Of® ces, Building Research Estab-
lishment, Garston, United Kingdom.
US Green Building Council (1998) LEED Buildings Green
Building Rating System Criteria, US Green Building
Council, San Francisco, California.
308
CRAWLEY AND AHO