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217Using LCA In a Green Building Projectmoreby Dominique Hes

Research Interests: Green Building, Green Building Materials (Architecture), Life Cycle Processes of Building Products, and Life Cycle Assessmentedit Download (.pdf)

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Using LCA in a green build ing proj ect

Dominique Hes

Centre for Design at RMITdominique.hes@rmit.edu.au

AbstractSustainability is a term easily used and well recognised to mean, among other things,responsible environmental performance. Within the building industry there are increasingpressures to integrate sustainability criteria in buildings. To do this what the industry needs isa methodology that gives the right answer at the right time, with rigour and integrity so thatdecisions are defendable.

This paper explores the role that LCA can have in the built environment. It begins by definingthe life cycle stages of the building process. Each stage is then analysed for its informationneeds, its impacts on the environmental performance of the building and the resulting lifecycle assessment technique, which can inform this stage. The discussion is illustrated by theuse of a case study outlining what is currently possible and the areas where further researchis needed to make LCA part of the answer.

Introduction

Sustainability is a term easily used and well recognised to mean, among other things,responsible environmental performance. Within the building industry there are increasingpressures to integrate sustainability criteria in building projects. To do this the industry needsa methodology that gives the right answer at the right time, with rigour and integrity so thatdecision are defendable.

This paper explores the role that Life Cycle Assessment (LCA) can have within the built

environment. It begins by defining the life cycle stages of the building process. Each stage isthen analysed for its information needs, its impacts on the environmental performance of thebuilding and the resulting life cycle assessment technique that could be used to inform thisstage.

Sustainability

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Sustainability Sustainability is a contested term but for this paper it is seen in as it was defined in theBrundtland Commission Report: “Our Common Future” [1]. Maintaining the environmental,social and economic system in such away as to not take away from future generations. In

Australia this has been translated in to the term Ecologically Sustainable Development (ESD)- development that uses, conserves and enhances the community’s resources so ecologicalprocesses on which life depends are maintained and the total quality of life, now and in thefuture, can be ensured [2].

Within the building industry this aim for ESD has not yet crystallised into a direction ormethodology with most fearing that they will, at some stage, need to address it with littleunderstanding of how. LCA in many ways is a methodology which some are looking towardsto give them the answers – the how to do sustainability – without understanding its strengthsand weaknesses or even what it does and how it does it. This paper explores this in simpleterms and with the use of a case study tries to outline what is currently possible and theareas where further research is needed to really make LCA part of the answer.

Life cycle of a building There are five main stages of the building life cycle (figure 1) as identified in the Building LifeCycle project [3], these are:

1. brief development2. design3. construction4. operation5. de-construction

Figur e 1 – Buildi ng Life Cycle

Concept designDesign brief

Estimators

Detailed Design

Mater ial Specifi cation

Detailed engineering

specification

Construction

phase

Use and

Maintenance

Refurbishment

End-of-life reuse/

recovery/

recycling/

disposal

Phase 1 Phase 2 Phase 3 Phase 4 Phase 5

Brief DevelopmentIn brief development the body that is thinking of building a new building defines how thisbuilding will function and determines the main issues it should address. Within the process of scoping out this brief often energy efficiency and other environmental attributes are included.It is at this stage that the greatest potential for minimising the buildings future environmentalimpact is determined. The brief sets the scene, outlines the requirements and determines thedirection of the new building.

It is at this stage that the brief development team needs to think about the life cycle of theirbuilding, carefully define its functions and determine their priorities. The main role for LCA at

this stage is as a methodology for guiding the thinking of the group. That is a building is not just something which you pay for at the start and that’s it! It has ongoing costs, ongoingimpacts and ongoing opportunities. It is at this stage that it is important to set quantitativeperformance goals. For example that the building should meet a 5 star rating, that it shoulduse no rainforest timbers, that it will collect and reuse rainwater, use no fossil fuels forheating and cooling, etc.

Life cycle thinking is therefore the appropriate tool for this part of the life cycle. That ishaving a basic understanding on how the decision made at the start of a project impact the

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having a basic understanding on how the decision made at the start of a project impact thelife performance of the building. There is no such summary that I am aware of a usefuldevelopment would be if a simple model brief was developed, based on LCA, possibly in asimilar form to the Sustainable Energy Authority of Victoria model brief [4].

In summary the main questions to be answered here are:1. Do we need a new building?2. What will be the function of the building and how best will this building fulfil these

functions?3. What quantitative goal do we want to put into the brief – including environmental?

Within this stage the decision also needs to be made between the ‘design and construct’ mode, Build/Own/Operate/Transfer (BOOT), staged design then construct and other models.Currently there is no information on the environmental impact difference of the models

though some research has just been started at the University of Queensland on theirefficiency [5]. From a life cycle perspective this type of study could be very interesting.

Design

Below we discuss the option of separate design then construct, it briefly outlines their LCAand information needs. Other methods of building design and construction will have slightlydifferent needs.

The design itself is divided into several stages: schematic design, detailed design anddocumentation (specification). While the brief will set the goals and has the greatestopportunity to influence the life cycle impact of the building it is the design, which makes thispotential concrete. It is at this stage that the greatest opportunities for minimising the impactof the building can be implemented. Both in the minimisation of operational impact andemergy (embodied energy) this stage is incredibly important.

In the concept or schematic design the important issues to look at are the orientation of the building, its use of the natural airflow, use of natural flora and the landform. In this phaselife cycle thinking is again the main focus - knowing that orientation and the other issues willhave a major impact on the operational performance of the building. Other issues to be

addressed here are if a rainwater tank or water treatment system is going to be used wherethis should be placed.

In summary the main questions to be answered here are:1. How do we minimise operational energy requirements?2. How do we meet the needs of the clients efficiently?3. How do we make the most use of those attributes already present on the site –

natural ventilations, orientations and vegetation?This stage therefore has the greatest impact on the ongoing performance of the building, theoperational aspect of the life cycle.

In detailed design the specifics of the building are developed, engineers are used for thetechnical details, the building’s materiality is resolved and time is spent with the clients toensure that the building is meeting their needs. It is here where the goals set for the projectat the beginning need to be looked at, ensuring that building design meets the definedtargets.

The information required here are detailed energy, lighting and comfort modelling tools.These are not LCA tools but are an important method for optimising the operational impact of the building. In determining the main materiality of the building information is required onthe relative impact of major materials such as concrete, steel, aluminium, timber, etc.currently emphasis is placed on emergy (value of the energy, and therefore green house gasequivalents, embodied by the material) rather than the full life cycle impact. Various studieshave shown that as the energy efficiency of a building improves the energy embodied in itsmaterials become more important [6,7,8], some studies showing that over the life of anefficient building the emergy can be up to 40% of the total energy impact [6]. Especially with

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efficient building the emergy can be up to 40% of the total energy impact [6]. Especially withthe current focus on greenhouse gasses the impact of energy is at the forefront in decision-making.

LCA’s role at this phase is in material decisions, to choose vinyl or linoleum, which type of insulation is best, etc.. But this stage also needs to be informed by indoor air qualityrequirements, currently IAQ is mainly informed by rules of thumb as there are no regulationsand standards, though research is being done by organisations such as CSIRO.

In summary the main questions to be answered here are:1. Which materials should we use?2. What is the trade-off between operational energy saved and extra materiality

(emergy)?

3. What are the indoor air quality impacts of the materials?

Finally, in the documentation phase of the design process all of the decisions made aboutthe form, the technology and the materiality are defined in precise and intricate detail. It ishere where the choices of specific materials are made and recommendations including

alternatives are documented. It is between the detailed design and the documentation thatwe currently find the greatest role for LCA. LCA tools that quickly and empirically can showthe result of a material selection [9] are the most practical examples of how LCA is used inpractice today.

In summary the main questions to be answered here are:1. In specifying materials which alternatives can be found based on life cycle impacts?2. What requirements can be written in to minimise life cycle impacts?

Construction

Once the building has been designed the documents are passed on to the builder. It isimperative that in doing so the targets set in the brief and designed into the previous phaseare also articulated in the contracts and requirements of the builders and sub-contractors.

A building may perform very well in simulations and may be designed to use the best

materials but if the builder does not build it to meet the design criteria it may perform wellbelow expected. The main issue at this stage is that in attempting to minimise costs, thecheaper rather than the most environmentally friendly option is often chosen. Even withthorough specification and documentation without constant vigilance the objectives of theproject can be subverted. This is not because the builder is a bad environmental citizen it issimply that priorities are to save money and time, not to meet environmental goals. It isimperative that within a life cycle optimised building the environmental goals are given equalweight to the financial ones.

From a life cycle performance perspective the main impact that this stage has is in building itas designed, the only real impact the construction process its self has is the generation of waste and immediate impacts of stormwater runoff, air pollution and noise.

In summary the main questions to be answered here are:1. What alternatives can be found based on life cycle impacts?

The tools which are required are:1. a tool that can quickly evaluate alternative material options if those which are

specified are not available2. well thought out contracts with specific goals3. clear methods for reporting the impacts of decision and progress.

OperationLife cycle assessment does not play a role in the decision making at this stage except when itcomes time to do any refurbishment. At the operational phase of the building, the mostimportant factor which influences the life cycle impact of the building is that it is use the way

04/02/2013 Using LCA In a Green Building Project | Dominique Hes - Academia.edu

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important factor which influences the life cycle impact of the building is that it is use the waythat it was designed – eg no opening the windows when the heating system is on.

In summary the main questions to be answered here are:1. Is the building performing as expected, if it is not performing as deigned why?

2. When refurbishing which materials should I choose?3. When refurbishing are the newer technologies which will give a life cycle saving?

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