Eco-Conscious Architecture Through Life Cycle Assessment ... · Life cycle assessment (LCA), also known as life cycle analysis (Fig. 3), is a technique that is used to assess the

csdCenter for Sustainable Development

Eco-Conscious Architecture Through Life Cycle

Assessment for BuildingsElena Rivera

Editor

Werner LangAurora McClain

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II-Strategies Analysis

2.15 Life Cycle Assessment for Buildings

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Introduction

“Few problems are less recognized, but more important than, the accelerating disappearance of the earth’s biological resources. In pushing other species to extinction, humanity is busy sawing off the limb on which it is perched.” Prof. Paul Ehrlich, Stanford University1

The U.S. Green Building Council reports that in the United States buildings alone account for:2

• 72% of electricity consumption,• 39% of energy use • 38% of all carbon dioxide (CO2) emissions• 40% of raw material use,• 30% of waste (136 million tons annually)• 14% of potable water consumption

Furthermore, in 1990 and 2005 the U.S. ranked highest in the world in energy con-sumption and carbon dioxide emissions, even though it ranked seventh in population.3

This data clearly indicates that the built environment has the potential to notably impact our environment and health. In spite of the knowledge that buildings contribute significantly to greenhouse gas emissions and consumer large amounts of energy and natural resources, the majority of buildings are still designed and built without considering the

environmental impacts of the building over its useful lifetime. The Office of Energy Efficiency & Renewable Energy, at the U.S. Department of Energy, reports that in the U.S.: 4

• Two to seven tons of waste (about 4 pounds per square foot) are generated during the construction of a new single-family detached house.

• 30 to 35 million tons of construction, reno-vation, and demolition (C&D) waste are produced by U.S. builders each year.

• Roughly 24% of the annual municipal solid waste stream is comprised of C&D debris.

• As much as 95% of building related construction waste is recyclable, and most materials are clean and unmixed. (Fig. 3)

• Construction waste is about 27% wood.The remaining 73% includes cardboard, paper, drywall/plaster, insulation, siding, roofing, metal, concrete, asphalt, masonry, bricks, dirt rubble, waterproofing materials, and landscaping material.

• 15 to 70 pounds of hazardous waste are generated during the construction of a detached, single-family house. Hazardous wastes include paint, caulk, roofing ce-ment, aerosols, solvents, adhesives, oils, and greases.

These statistics suggest that the process of designing, building, and operating buildings

Eco-Conscious Architecture Through Life Cycle Assess-ment for Buildings

Elena Rivera

Based on a presentation by Dr. David T. Allen

Figure 1: Buildings such as these all have life cycles that encompass construction, operation, and demolition

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offers significant opportunities to reduce the burden on the environment. Those involved in the building sector - architects, designers, builders, developers, and planners - have an opportunity to make decisions that can have a dramatic influence on reducing the envi-ronmental impacts of the built environment. The collection and analysis of general data on the byproducts of the construction process as well as the availability of extensive data on specific products has led to the creation of tools that can assist in assessing the impacts of buildings over their lifetime. These tools are generally referred to as life cycle assessment or life cycle analysis (LCA) tools. Life cycle analysis tools

Architects, designers, builders, building product manufacturers, and others in the building design and construction profession, are being encouraged or even required to take performance-based and prescriptive actions toward reducing environmental impacts related to their practices in, or related to, the built environment. Increasingly this is being accom-plished, or at least attempted, by using one or more LCA tools, e.g., LCA software programs, standards and guidance documents. While multiple LCA tools exist, along with a wealth of information, guidance, and standards on as-sessing the environmental impacts of buildings and suggestions for reducing those impacts, there is no definitive tool or path to follow when it comes to LCAs.

Most of the currently available LCA informa-tion, databases, and tools have come about as a result of several, sometimes simultaneous or partially overlapping, efforts by research institutions and/or academic groups working as partners across the world. Organizations such as the International Organization for Standardization (ISO), the Society of Envi-ronmental Toxicity and Chemistry (SETAC),

the European Committee for Standardization (CEN), the ATHENA Sustainable Material Insti-tute in Canada, the Danish Building Research Institute (SBI) in Denmark, the U.S. National Institute of Standards and Technology (NIST), the Building Research Establishment (BRE) in the UK, the U.S. Green Building Council, the Royal Institute of Technology in Sweden, the University of Karlsruhe in Germany, and others have been, or are currently, involved in devel-oping LCA standards, tools and/or guidance.

The tools have been developed over the last 20 years for different purposes by various organizations in multiple countries. As a result the tools vary greatly.4 Some tools are ap-plicable to a range of buildings, while others are specific to certain types (e.g., commercial vs. residential). Even tools that cover the same life cycle stages cover them differently and rely on different databases or guidelines, therefore they yield different results that can-not be compared. Regional regulations and cultural factors also have an impact on the development of LCA tools, thus accounting for other differences among the tools. This makes comparing the tools difficult and determinin-ing which tool is suitable for a particular user or a specific project is challenging, which may discourage their use and application.4

The development of standardized LCA tools for buildings or the integration of LCA into the design and policymaking process is made more difficult by the complexity of build-ings. For example, a single building can be composed of over 60 basic materials and over 2,000 separate products. Furthermore, according to the International Energy Agency (IEA) Annex 31 report,5 typically a wide variety of LCA tools are needed, as opposed to just one, since effective LCA tools need to be tailored to the specific planning phase and the user’s knowledge base.

There are some concerns that not all LCA results are useful for comparing products, buildings or systems since some factors either get diluted or misrepresented during the life cycle inventory step or by inconsistent system boundaries, rendering the final results poor indicators on which to base decisions. Also, the inability to account for site or location spe-cific characteristics can impact the results of a LCA ,since factors such as microclimate, the impact of one building on an adjacent building, and infrastructure loading in urban areas may not be represented in LCAs.6 However, in spite of these limitations, LCAs have demonstrated benefits for evaluating overall material and energy efficiency, identifying trade-offs in pollu-tion, materials, energy, and operations, as well as for benchmarking efficiency improvements and emission reductions.7

In spite of these concerns and challenges, LCA continues to be used and is considered particularly useful during the design phase, since it offers the opportunity to identify po-tential environmental issues early on so that they can be addressed in the design phase.8 As LCA methodologies, tools, and applica-tions continue to be studied and refined, LCA practitioners and users should gain greater expertise in combining LCA with other assess-ment tools and using the results to support decisions aimed at lowering environmental impacts or improving upon current conditions through regenerative or restorative design.

This paper will provide an overview of the LCA methodology, including the basic steps for conducting a LCA, how it is being applied to buildings and the built environment, and will provide a listing, comparison and classifica-tion of several of the many LCA tools currently available, based on a literature review by other authors, to serve as general guidance in navigating the LCA tools.

Overview of the LCA process

“In principle, all decisions that affect or are meant to improve the environmental perfor-mance of a product/service should be scruti-nized in terms of their life cycle implications. For the environmental perspective, a product’s life cycle can be represented as a circular movement that ties together resource extrac-tion, production, distribution, consumption and disposal. In other words, all the phases of organized matter and energy that are in some way related to the making and use of a product can also be linked to an impact on the environ-ment.” 9 Organization for Economic Co-opera-tion and Development, Paris, France, 1995

Life cycle assessment (LCA), also known as life cycle analysis (Fig. 3), is a technique that is used to assess the environmental impacts associated with a product, process, or system, from cradle-to-gate, cradle-to-grave or, if it can be recycled, cradle-to-cradle. The concept of creating cradle-to-cradle materials - closing the loop by not generating any waste - has recently been championed by William Mc-Donough and Michael Braungart as a systems that imitates “nature’s effective cradle-to-cradle system of nutrient flow and metabolism, in which the very concept of waste does not exist”.10

Figure 4 provides a simplified diagram of the stages of a life cycle for a product. A cradle-to-grave LCA for a product might assess the impacts from the following stages: raw material harvesting, extraction or acquisition; manufac-turing or refining; packaging and distribution/transportation; use; and disposal, recycling

Figure 2: U.S. Carbon Dioxide (CO2) Emissions by Sector


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or reuse. Embedded in this analysis is the energy and natural resource consumption for all stages, as well as waste generation and emissions to air, water and soil. Some LCA methodologies also include an assessment of social, cultural, community and/or economic impacts. Therefore, a LCA is said to be holistic because it is designed to cover essentially all phases of a product’s life cycle and all signifi-cant impacts, both direct and indirect, that the product has on the environment.11

As a methodology, LCA involves “compiling an inventory of relevant inputs and outputs for a clearly defined system, and then evaluating the potential environmental impacts associ-ated with those inputs and outputs. Results are [then] interpreted in relation to objectives established at the outset.”12 LCA is sometimes confused with the life-cycle costing (LCC) methodology, which differs in that LCC is used to calculate the total cost of ownership over the useful life of the product, whereas LCA involves a qualitative and/or quantitative analysis of environmental impacts over the life of the product. “The two tools are related in that they both take into account how long a particular item will serve its intended purpose and what maintenance it will need during that time. As a result, both tools give credit to items that are long-lived and durable, but LCA involves environmental accounting, while LCC only considers economic value.”13

Often, LCAs are applied to products on a cradle-to-gate, rather than cradle-to-grave basis. This means that the life cycle assess-ment includes the process of extracting or harvesting the raw materials (the cradle); the intermediate processing, refinement, and fabrication processes; and the manufacture of the final product ready for sale (the factory gate). Since a building or built environment is intended for a use, or life, beyond the factory gate, LCAs for buildings are conducted on a cradle-to-grave, or even cradle-to-cradle, basis. Therefore, data from product LCAs are incorporated into the LCAs for built systems.

When LCA is applied to a building instead of a product, the life cycle stages can be differenti-ated as: raw material extraction/acquisition (Fig. 5), building material manufacturing (Fig. 6), site preparation and onsite construction (Fig. 7), building use, operation and mainte-nance (Figs. 8 & 9), and demolition, recycling/reuse and/or disposal (Fig. 10). Since different LCA tools have different applications or are in-tended for different users, using a combination of tools is most beneficial. In this approach, a different LCA tool might be selected for each phase, depending upon the objectives of each. Therefore, rather than using a single LCA, a building and its components would undergo Figure 4: Product life cycle

Figure 3: Life Cycle Analysis of a Building

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several LCAs, the results of which can be used at the appropriate stage and/or are integrated to support decision making from the design phase on through the entire life cycle of the building. Specific LCA tools are addressed in a later section in this paper.

LCA phases

The LCA process is carried out in a system-atic, phased approach and is comprised of the following four steps:14 goal definition and scope, inventory analysis, impact assess-ment, and interpretation. These four steps or phases are described below and partially illustrated using information from a case study on a residential home in Ann Arbor, Michigan that was analyzed using LCA methodology in order to design a more energy efficient home. A LCA was conducted on a 2,450 square foot residential home built in Ann Arbor, Michigan to determine total energy consumption of building material manufacturing and of construction, use and demolition over a 50-year period, and to determine the global warming potential (GWP) and life cycle cost. The LCA consisted of an assessment of an existing standard home in comparison to a new energy efficient home.

Step 1: Goal definition and scope

The first step in a LCA is to define the goal and scope of the assessment in order to determine the time and resources required. Therefore, this first step includes deciding and determin-ing:

• Why the LCA is being conducted.• What product, process or system will be

studied.• What the functional unit(s) will be for the

product, process or system.• What the boundaries or limits of the as-

sessment will be, including spatial and temporal boundaries (e.g., what will be included and what will be excluded).

• Which environmental concerns will be included (impact categories).

• What will be the strategy for data collection• Who will be the audience of the LCA

- whether it will be a public and peer reviewed document.15

For the Michigan home case study, the LCA was conducted to help determine how to de-sign an energy efficient home using an existing home for comparison.16 As stated above, the LCA covered energy consumption, GWP, and cost over the life cycle of the home, which was taken to be 50 years.

Defining the system boundaries sets the limits for data collection for the study and can have

Figure 5: Cement plant Figure 7: Under construction

Figure 6: Building materials

Figure 8: Coal mining for electricity generation Figure 9: Power lines transmitting electricity

Figure 10: Demolition


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a significant impact on the outcome of the LCA. As an example, if you were conducting a LCA that compared incandescent light bulbs to fluorescent lamps to determine which one had the least impact on the environment, you could choose the system boundary to include only the disposal of the bulbs, or you could set the boundary to encompass the entire life cycle of the bulbs (see Figure 11). If you chose to examine only disposal of the bulbs, the fluorescent lamps would appear to be a much worse choice than the incandescent bulbs, since they contain mercury, a hazardous material that would be released upon disposal. However, if the entire life cycle of the lamps is considered, the incandescent bulb would have the higher mercury releases, since more mercury is released by burning coal to provide energy for the less efficient incandescent bulb than is released by using and disposing of the fluorescent bulb. This example illustrates how the choice of system boundary impacts the outcome of the LCA.17

Setting boundaries that are too narrow can lead to decisions that are not grounded in criti-cal data, and trying to include every aspect of the life cycle would be too time and resource intensive, if not impossible. Selecting the system boundary should be based on best practices and good engineering judgment, e.g. on the components that account for 1% or more of the raw material use, energy use, and wastes or other emissions.18 Selection of the system boundary should also consider the ob-jective of the LCA as well as elements or steps that could provide critical data. For example, life-cycle elements such as raw materials extraction or acquisition and waste generation can rarely be excluded. If the LCA is being conducted to compare two products and an element is identical for both, then perhaps it can be excluded if the only goal of the analysis is the comparison of the two products. For ex-ample, if the LCA involved two products which generate identical solid waste streams, but different air emissions streams, then perhaps the solid waste element could be excluded.

The system boundaries for the Michigan home included energy consumption and GWP gas emissions for processes such as, but not limited to, the following:

• Embodied energy from the following pro-cesses: raw material extraction, production of engineered materials like steel plates and wood studs, manufacturing of building components like windows, carpet, and appliances, transportation of materials from raw material extraction to product manufacturing to construction site, and maintenance or improvement of materials.

• Onsite construction, including site prepara-Figure 11. System Boundaries: Top diagram shows system boundary for fluorescent lamps and incandescent lamps taken only around disposal of each type of lamp vs. bottom diagram with system boundary around entire life cyle of each type of lamp.

tion.• Energy (e.g., from utilities) consumed dur-

ing the occupancy and use phase.• Demolition of the home at the end of its

useful life.• Transportation of demolished materials to

recycling centers or landfills, excluding the concrete foundation and basement floor, which it was assumed would remain in place.

In order to highlight those systems in the built environment that directly influence the energy use and GWP of a residential home, pro-cesses and factors such as, but not limited to, the following were excluded from the boundary system for the Michigan home:

• Site location as it pertains to impacts on local ecosystems, personal transportation issues, and urban planning issues.

• Energy and material issues related to the surroundings, such as landscaping and the concrete in the driveway.

• Non-appliance furniture.• Utility and TV/phone/data connections and

hook-ups.

• Behavioral preferences of inhabitants, such as food, clothing, furniture, and enter-tainment equipment.

• Indoor air quality issues.• Energy consumption related to treating/

supplying water and waste treatment, and trash pick-up and disposal.

• Construction and demolition equipment.• The embodied energy of the industrial

facilities that produced raw materials and fabricated products.

• Environmental issues (e.g., resource use) and social issues (e.g., effects on local economy) related to the origin of the con-struction materials.

When conducting a LCA, the choice of func-tional unit is important because it provides the means for comparing products and the basis for calculating the inputs and outputs in the inventory step. The ISO standards note that the functional unit must be clearly defined and measurable. When comparing the impacts of two different paints, the function of the paints is to cover or coat a surface, so the func-tional unit could be one square foot of painted surface. In this case the resource and energy

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requirements and the waste and air emissions per square foot could be normalized to this unit in order to compare different paint products.19 However, the lifetime of the paints would also need to be considered in the LCA, since the lower emissions of one paint product could be offset if it required more frequent reapplication. So the functional unit is better defined as one square foot for 20 years. This would capture environmental impacts from the original appli-cation as well as any reapplications during that time frame for both paints.In order to compare the existing home to the desired energy-efficient home, functional units such as the following were defined in the Michigan home case study:

• Internal/usable floor area: 2,450 ft2.• Internal usable building volume: 26,960 ft3.• Occupancy: 4 people.• Life span of home: 50 years.• Basement and garage area: 1,675 ft2 and

484 ft2 respectively.• omparable thermal comfort, indoor air

quality, daylighting, and lighting intensity in both homes.

• Municipal supply of potable water.• In-home generation of hot water with a

natural gas boiler.• In-home heat generation with natural gas

furnace; cooling with central air-condition-ing unit.

• Grid-supplied 110-volt electricity

Step 2: Inventory analysis

The second step in a LCA is to inventory the inputs and outputs for all phases of the life cycle based on the system boundaries defined in step one. Inputs may include raw materi-als and energy, and outputs may consist of products, solid wastes, wastewater discharges and air emissions. This step, known as the life cycle inventory (LCI), is shown conceptu-ally in Figure 12. It usually takes the most time and effort, since it involves collecting data to quantify all of the inputs and outputs, allocate energy and material flows, validate the data for the specific system, refine the system boundaries, normalize data to the functional unit selected, and creating tables or graphs for use in the next step: impact assessment.

Challenges in this LCI step include tracking material flows, allocating material and energy usage and emissions, and achieving a hig level of data aggregation. For example, the LCI for the production of ethylene, a chemical used in the production of other chemicals such as ethylene oxide, would require gathering data on all the input and output material flows, fuels used as feedstock, fuels used for energy, other feedstock, raw materials, air emissions, water emissions, and solid waste generation.20

One source of data for the inventory analysis is the U.S. Life-Cycle Inventory (LCI) Data-base.21 The LCI Database was created by the National Renewable Energy Lab (NREL) and its partners (including the Athena Institute) to help answer questions about environmental impact when conducting a LCA.22 The online database provides a cradle-to-grave account-ing of the energy and material flows into and out of the environments that are associated with producing a material, component, or assembly. It contains data on commonly used materials, products, and processes.

For the Michigan home LCA, the majority of the energy and GWP data sets were obtained from the DEAM software database, which has information on a wide range of materials. En-ergy-10 was used for energy simulations. The inventory was then divided into eight home systems: walls, roof/ceilings, floors, doors/windows, foundation, appliances/electrical, sanitary/HVAC, and cabinets.

Step 3: Impact assessment

During the third step of the LCA process, called the life cycle impact assessment, the extensive data collected in the LCI step is con-verted to indicators for each impact category. The indicators correlate to the impacts without actually measuring them. Thus, climate change is measured using the global warming potential of greenhouse gases released into the atmosphere. In this way, information about the greenhouse gas releases is combined

as an overall effect on the climate, without having to model the actual impacts on health or ecosystems caused by the changes in the atmosphere.23

Possible impacts to consider in this step include:

• Land use • Resource depletion• Air quality• Water quality and quantity• Global warming potential from CO2 and

other greenhouse gas emissions • Toxicity to humans, animals, or both• Energy, including grey or embodied energy• Solid waste emissions• Stratospheric ozone depletion• Smog• Acidification• Eutrophication • Natural resources, including habitat,

water, fossil fuels, minerals, and biological resources

• Human toxicity• Ecotoxicity

For the Michigan home LCA, only the impacts from energy use and global warming potential were analyzed.After determining the indicators, the impact indicator results can be combined to yield a single number score. Alternatively, the impact results can be normalized into units that can be compared more readily to help users put the results into perspective.24

Figure 12: Life Cycle Inventory (LCI) for a Building


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Among the possible impacts listed above, one deserves particular attention: energy, in particular grey and embodied energy. The terms “grey energy” and “embodied energy” are sometimes used interchangeably; how-ever, grey energy is properly used to refer to the energy required for transporting building materials (Fig. 13) and can either be consid-ered as separate from the embodied energy or as a component of embodied energy.25 According to a report by the U.S. Department of Energy (DOE), “Embodied energy is the energy required for extraction or harvesting of raw materials and manufacturing the raw materials into products for buildings. Some definitions of embodied energy also include the energy required for transporting a material to the construction site, but the embodied en-ergy research performed by DOE’s Industrial Technologies Program focuses on extraction and/or manufacturing processes.”

Step 4: Interpretation During the fourth step of the LCA, the results of the impact assessment are reviewed for appropriateness, completeness, and accuracy. They are then interpreted to provide guid-ance to the LCA users on how to use the LCA results for improving environmental perfor-mance.26 It is likely that the LCA process will require estimates and assumptions, which will likely include making value judgments. Any such estimates, assumptions, and value judg-ments should be communicated in the final results and considered when drawing conclu-

sions. It is not uncommon to end up with alternatives that are not clearly differentiated in terms of their environmental impacts. How-ever, the results can still be helpful in gaining a greater understanding of the potential impacts, thus suggesting a path to a different alterna-tive or supplying enough information to weigh the alternatives in light of other factors such as geographic or spatial considerations.

For the Michigan home, employing energy efficiency strategies and materials with lower embodied energy, reduced the pre-use phase energy by 3.9% while use-phase energy (space and water heating, lighting, plug loads, and embodied energy of maintenance and im-provement materials) was reduced by 67.4%. The total energy consumption and the GWP for the energy efficient home were decreased by 63% compared to the standard home. Overall, the total life cycle energy was reduced by a factor of 2.73, and life cycle GWP by a factor of 2.71.

The most significant difference was the 12” thick, R-35 walls (filled with cellulose insula-tion) that were used on the energy efficient homes. Using cellulose, which has less embodied energy and thus lowered the energy for the pre-use phase, increased the thermal resistance of the wall by a factor of three. Combined with doubling the insulating value in the ceiling, this greatly improved the perfor-mance of the thermal envelope for the energy efficient home.

The total life cycle energy for the energy-effi-cient home, compared to the standard home, is depicted in Figure 14. It has been broken down into three stages: (1) the pre-use phase, which included all the embodied energy of construction and maintenance/improvement materials, (2) the use phase, which included all of the energy for operating and maintaining the home over 50 years, and (3) the demolition phase, which included all of the demolition and transportation energy. The chart shows that the majority of the energy consumption occurs in the use phase as compared to the pre-use (embodied energy) and demolition phases.

LCA tools

Many building sector websites provide general information on LCA and include lists of LCA tools and other resources. For example, the United States Green Building Council (US-GBC) website provides a list of links to “Life Cycle Analysis and Costing” resources.27

However, a review of articles, reports and online resources that assess LCA tools leads to many resources but no one coherent method for navigating the LCA world. Based on the literature review for this paper, a good place to search for a LCA tool for a building or building components would be the IEA Annex 31, “Directory of Tools: A Survey of LCA Tools, Assessment Frameworks, Rating Systems, Technical Guidelines, Catalogues, Checklists and Certificates”28

The Annex 31 Directory of Tools provides a quick overview of current tools in terms of their functions, audience, users, software applica-tions, technical support, data requirements, strengths, availability, and contact information. The directory, which is designed to comple-ment the U.S. DOE Office of Energy Efficiency and Renewable Energy (EERE) “Building Energy Software Tool Directory”, lists tools in 13 countries including several in the U.S.29 The directory separates the tools into five types: Energy Modeling Software, Environmental LCA Tools for Building or Building Product, En-vironmental Assessment Frameworks, Rating Systems (Whole Buildings or Building Stocks), Environmental Guidelines or Checklists for Building Design/Management, and Envi-ronmental Product Declaration, Catalogue, Reference Information, Certification, Label. Of these five categories, the last three are comprised of what Annex 31 refers to as “pas-sive tools”, which they think are best suited for decision support and are best applied “within the fast-paced processes involving design professionals.”30 However, if more sophisticat-ed tools are required, the U.S. DOE Building Energy Software Tool Directory referenced in the Annex 31 Directory of Tools appears to be

Figure 13: Embodied or grey energy related to transportation

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a good resource.

The U.S. DOE Building Energy Software Tool Directory is an online directory which provides information on over 300 building software tools, including databases, spreadsheets, and simulation programs for evaluating energy efficiency, renewable energy, and sustainability in buildings. The tools can be listed alphabeti-cally, by platform (Mac, PC, Unix or Internet), by country or by subject. The directory list includes tools for whole building analysis of energy simulation, load calculation, renewable energy, retrofit analysis, and sustainability/green buildings, as well as tools for materials, components, equipment and other applica-tions. Furthermore, the directory includes a short description along with information on expertise required, users, audience, input, output, computer platform, programming lan-guage, strengths, weaknesses, contacts, and availability for each tool.30

The majority of these applications can be used for life cycle assessment as well as related material and energy analyses applicable to the built environment. However, further information on any of the applications, such as exper-tise required, requires going to a separate webpage for each application, which makes comparing the tools somewhat cumbersome.A recent study, published in Environmental Impact Assessment Review, analyzed and categorized thirteen LCA tools.31 According to the study, there are two well-known classifica-tion systems for LCA tools. One is the Annex

31 tool directory described above. The other is a simple three-level classification for LCA tools created by the Athena Institute, a non-profit organization that seeks to improve the sustain-ability of the built environment:

• Level 1 - product comparison tools and information sources

• Level 2 - whole building design or deci-sion support tools

• Level 3 - whole building assessment frameworks or systems.

A fourth category includes supporting tools and techniques, such as Baseline Green, developed by Pliny Fisk and Greg Norris of The Center for Maximum Potential Build-ing Systems in Austin, Texas.32 To facilitate comparison of tools, the authors combined the two classification systems, using the Athena system as the basis since it categorizes the assessment tools according to where they are used in the assessment process and for what purpose, which facilitates comparing tools within levels.

The 13 LCA tools were listed according to level and were compared in terms of the types of buildings to which they could be applied. The study concluded that comparing LCA tools is a difficult task since each tool is designed dif-ferently, relying on different databases, with an emphasis on different life cycle phases, aimed at assessing different types of buildings.

Other LCA Case Studies

Below are summaries of two other LCA case studies: LCA applied to a building (a stadium) and LCA applied to a building enclosure (wall and roof materials).

Case Study 1: The Olympic Stadium in Aus-tralia33

A software tool created by the NSW Depart-ment of Public Works and Services (DPWS) based on the Boustead 3 model, but using Australian data, was used to perform a LCA analysis of three designs – a conventional sta-dium design, a better environmental practice design, and a best practice design. The results were analyzed and the better environmental practice design chosen. The LCA was used to evaluate and select the materials as well as the energy and water consumption, which resulted in a stadium design with reduced environmental impacts that became a bench-mark for other stadium projects. The improved design provided an annual primary energy savings of 30%, a 37% reduction in green-house gas emissions, and a 13% reduction in water use, with 77% of water coming from onsite recycling or onsite water collection.

Case Study 2: Single-Story Houses in Indo-nesia34

A LCA was conducted on the enclosures of single-story houses, the typical building type in Indonesia. The study revealed that the initial embodied energy of a typical brick and clay roof enclosure was 1gigajoule (GJ) more than that for other typical wall and roof material (cement based). However, over the 40-year life span of the houses, the clay-based houses demonstrate better energy performance than the cement-based ones. This led to the conclu-sion that material selection during the design phase is crucial, since the buildings have a lifespan of at least 40 to 50 years.

Conclusions

LCAs have demonstrated benefits in evaluat-ing overall material and energy efficiency as well as benchmarking efficiency improvements and emission reductions. Architects, design-ers, builders, building product manufactur-ers, and others in the building design and construction profession have access to LCA software programs, standards, and guid-ance documents to help guide their decisions when designing, operating, maintaining and/or remodeling buildings. However, navigating the available LCA tools is not a straightforward task. A few tools, such as the IEA Annex 31 Directory of Tools and the U.S. DOE’s Building

Figure 14: Total Life Cycle Energy for Michigan Home Case Study


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Energy Software Tool Directory can be help-ful in selecting the right tools for the various components and life cycle stages. Studies have been, and will continue to be, conducted to assess and compare the various LCA tools. The results of such studies can be helpful in navigating the available tools to determine the best options.

As LCA tools continue to undergo improve-ments and inventory data continues to be generated and refined, system boundaries and functional units must be carefully selected. Furthermore, the results should be used judiciously. When there is doubt as to the best alternative, options can be considered in terms of the local, cultural, social, and economic context, or the analysis can be extended to include other components that could provide an even more holistic assessment.

In spite of concerns and challenges, LCA continues to help shape emerging green building technology, in particular with regard to assessing energy use and global warm-ing potential in order to address these in the design phase. LCA practitioners and users are gaining greater expertise in combining LCA with other assessment tools and using the results to support their decisions to lower environmental impacts or even to improve upon current conditions through regenerative or restorative design.

Notes

1 The Institute for Market Transformation to Sustainability, http://www.sustain-ableproducts.com/mts/about.htm#join.

2 U.S. Green Building Council, http://www.usgbc.org/DisplayPage.aspx?CMSPageID=1718.

3 U.S. DOE/Energy Efficiency and Renew-able Energy, “Chapter 1.1 Buildings Sec-tor Energy Consumption”. In Buildings Energy Data Book (September 2008), http://buildingsdatabook.eren.doe.gov/ChapterView.aspx?chap=1#1.

4 Haapio, Appu, and Pertti Viitaniemi, 2008. “A critical review of building environmen-tal assessment tools”, Environmental Impact Assessment Review 28, no. 7: pp. 469-482. Environment Index, EBSCOhost (accessed October 15, 2008).

5 Annex 31, Energy related environmental impact of buildings”, is a project estab-lished under the auspices of the IEA Energy Conservation in Buildings and Community Systems Programme in Canada, in which fourteen countries par-ticipated (Australia, Canada, Denmark,

Finland, France, Germany, Japan, Neth-erlands, New Zealand, Norway, Sweden, Switzerland, United Kingdom and United States of America). Canada served as the coordinating agency for the project.

6 Kohler, Niklaus and Sebastian Moffatt, 2003. “Life-cycle analysis of the built envi-ronment”, UNEP Industry and Environ-ment, April-September 2003, pp. 17-21.

7 Owens, J.W., 1997. “Life Cycle As-sessment: Constraints on Moving from Inventory to Impact Assessment”, Journal of Industrial Ecology, Volume 1, Number 1, Massachusetts Institute of Technology and Yale University.

8 Ibid9 National Renewable Energy Lab, U.S.

Life Cycle Inventory Database, http://www.nrel.gov/lci/assessments.html.

10 McDonough, William and Michael Braun-gart, 2002, Cradle to Cradle: Remaking the Way We Make Things, New York: North Point Press, pp. 103-104.

11 Schenck, Rita, 2002. “Life Cycle Assess-ment: the Environmental Performance Yardstick”, American Center for Life Cycle Assessment, Institute for Environmental Research and Education, Produced for Earthwise Design, Life Cycle Assessment Realities and Solutions for Sustainable Buildings January 19th 2002, Antioch University, http://www.lcacenter.org/LCA/LCA-yardstick.html.

12 Highlight Report of Annex 31 - Energy-Related Environmental Impact of Buildings, a project established under the auspices of the International Energy Agency’s (IEA) Energy Conservation in Buildings and Community Systems Pro-gramme, p. 8., http://www.greenbuilding.ca/annex31/Main/highlight_report.htm.

13 Malin, Nadav, 2002. “Life-Cycle As-sessment for Buildings: Seeking the Holy Grail, Feature from Environmental Building News”, March 1, 2002, http://www.buildinggreen.com/auth/article.cfm?fileName=110301a.xml.

14 Life Cycle Assessment: Principles and Practice by Scientific Applica-tions International Corporation (SAIC), EPA/600/R-06/060, May 2006, http://www.epa.gov/ORD/NRMRL/lcaccess/pdfs/600r06060.pdf.

15 Schenck, Rita, 2002. “Life Cycle Assess-ment: the Environmental Performance Yardstick”, American Center for Life Cycle Assessment, Institute for Environmental Research and Education, Produced for Earthwise Design, Life Cycle Assessment Realities and Solutions for Sustainable Buildings January 19th 2002, Antioch University, http://www.lcacenter.org/LCA/

LCA-yardstick.html.16 Blanchard, Steven and Peter Reppe,

1998. “Life Cycle Analysis of a Resi-dential Home in Michigan”, A project submitted in partial fulfillment of require-ments for the degree of MS of Natural Resources at the University of Michigan, Sponsored by the National Pollution Pre-vention Center, October 1998, http://www.umich.edu/~nppcpub/research/lcahome/.

17 Rosselot, Kirsten and David T. Allen, 2001. “Life-Cycle Concepts, Product Stewardship and Green Engineer-ing”, Chapter 13 in Green Engineering: Environmentally Conscious Design of Chemical Processes, D. T. Allen and D. Shonnard, Prentice Hall, Englewood Cliffs, http://www.utexas.edu/research/ceer/greenproduct/dfe/chap13.htm.

18 Ibid19 Ibid20 Owens, J.W., 1997. “Life Cycle As-

sessment: Constraints on Moving from Inventory to Impact Assessment”, Journal of Industrial Ecology, Volume 1, Number 1, Massachusetts Institute of Technology and Yale University.

21 National Renewable Energy Lab, U.S. Life Cycle Inventory Database, http://www.nrel.gov/lci/, http://www.nrel.gov/lci/database/.

22 NREL is a national laboratory of the U.S. Department of Energy, Office of En-ergy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

23 Rosselot, Kirsten and David T. Allen, 2001. “Life-Cycle Concepts, Product Stewardship and Green Engineer-ing”, Chapter 13 in Green Engineering: Environmentally Conscious Design of Chemical Processes, D. T. Allen and D. Shonnard, Prentice Hall, Englewood Cliffs, http://www.utexas.edu/research/ceer/greenproduct/dfe/chap13.htm.

24 Schenck, Rita, 2002. “Life Cycle Assess-ment: the Environmental Performance Yardstick”, American Center for Life Cycle Assessment, Institute for Environmental Research and Education, Produced for Earthwise Design, Life Cycle Assessment Realities and Solutions for Sustainable Buildings January 19th 2002, Antioch University, http://www.lcacenter.org/LCA/LCA-yardstick.html.

25 Presas, Luciana Melchert Saguas, 2005. Transnational Buildings in Local Environ-ments, England: Ashgate Publishing, Ltd., p. 42.

26 Schenck, Rita, 2002. “Life Cycle Assess-ment: the Environmental Performance Yardstick”, American Center for Life Cycle

12


Assessment, Institute for Environmental Research and Education, Produced for Earthwise Design, Life Cycle Assessment Realities and Solutions for Sustainable Buildings January 19th 2002, Antioch University, http://www.lcacenter.org/LCA/LCA-yardstick.html.

27 See list of LCA and LCC links on the USGBC website at: http://www.usgbc.org/DisplayPage.aspx?CMSPageID=76.

28 Available for download at: http://www. greenbuilding.ca/annex31/Main/dir_tools. htm. 29 U.S. DOE/Energy Efficiency and Renew-

able Energy, Building Technologies Program, Building Energy Software Tool Directory, http://apps1.eere.energy.gov/buildings/tools_directory/.

30 “Types of Tools”, Core report to Annex 31: Energy-Related Environmental Impact of Buildings, p. 2, http://www.greenbuilding.ca/annex31/pdf/D_types_tools.pdf.

31 Haapio, Appu, and Pertti Viitaniemi, 2008. “A critical review of building environmen-tal assessment tools”, Environmental Impact Assessment Review 28, no. 7: pp. 469-482. Environment Index, EBSCOhost (accessed October 15, 2008).

32 Fisk, Pliny and Greg Norris, “Building GreenTM – A Green Building Design Methodology”, The Center for Maximum Potential Building Systems, http://www.cmpbs.org/publications/T1.7-Baseline-Green.pdf.

33 Greening the Building Life Cycle, http://buildlca.rmit.edu.au/menu9.html.

34 Utama, Agya and Shabbir H. Gheewala, 2008. “Life cycle energy of single landed houses in Indonesia”, Energy & Buildings; Oct2008, Vol. 40 Issue 10, p1911-1916.

Figures

Figure 1: Tokyo buildings: http://farm1.static.flickr.com/21/30259947_cc46aaca0d.jpg?v=0.

Figure 2: Based on U.S. Energy Information Administration statistics per Architecture 2030 source at http://www.architecture2030.org/building_sector/index.html

Figure 3: Construction waste at http://www.inhabitat.com/wp-content/uploads/pvc.jpg.

Figure 4: Life Cycle Analysis of a Building, from INTRON website at http://www.intron.nl/site_eng/thema_lca.aspx.

Figure 5: Based on figure by David T. Allen, Life Cycle Assessment Overview, online at http://www.utexas.edu/research/ceer/green-product/pages/life_cycle_assessment_er.htm.

Figure 6: Conrete plant: http://farm1.static.flickr.com/99/302360315_79defcc208.jpg?v=0.

Figure 7: Building materials (bricks): http://www.rics.org/NR/rdonlyres/A5D348DB-F006-454A-8466-124DEAD9BC7B/0/bricks.png.

Figure 8: Under construction: http://www.sxc.hu/photo/958918.

Figure 9: Coal miing: http://upload.wikimedia.org/wikipedia/commons/b/b3/Strip_coal_min-ing.jpg

Figure 9: Power lines: http://www.sxc.hu/photo/1075609.

Figure 10: Demolition of Chemistry Building at The University of Texas at Austin, by Dr. Werner Lang

Figure 11: From Chapter 13 in Green Engi-neering: Environmentally Conscious Design of Chemical Processes, by D. T. Allen and D. Shonnard, Prentice Hall, Englewood Cliffs, 2001, online at http://www.utexas.edu/re-search/ceer/greenproduct/dfe/PDF/Chap13fi-nal.PDF

Figure 12: Developed for this paper by Elena Rivera

Figure 13: Truck transporting logs, at http://www.sxc.hu/pic/m/r/re/renaudeh/1019695_log-ging_truck.jpg.

Resources

Architecture 2030: http://www.architec-ture2030.org/

Building Green: http://www.buildinggreen.com/

Energy Star: http://www.energystar.gov/

EPA, Life Cycle Assessment: Principles and Practice: http://www.epa.gov/nrmrl/lcaccess/lca101.html

Green Building Initiative website: http://www.thegbi.org/commercial/life-cycle-assessment.asp

Green Product and related website, Dr. David T. Allen, University of Texas at Austin, Depart-ment of Chemical Engineering: http://www.utexas.edu/research/ceer/greenproduct/

Healthy Building Network: http://www.healthy-building.net/index.html

IEA Annex 31: http://www.greenbuilding.ca/

annex31/index.html

Sustainable Building Information System: http://www.sbis.info/index.jsp

UNEP Life Cycle Initiative: http://jp1.estis.net/sites/lcinit/default.asp?site=lcinit

U.S. DOE Buildings Energy Data Book: http://buildingsdatabook.eren.doe.gov/ChapterView.aspx?chap=1

Whole Building Design Guide: http://www.wbdg.org/tools/tools_cat.php?c=3

Biography

Dr. David T. Allen is the Gertz Regents Profes-sor of Chemical Engineering, the Director of the Center for Energy and Environmental Resources, and the Director of the Energy In-stitute at the University of Texas at Austin. He is the author of six books, including a textbook on the design of chemical processes and prod-ucts that was jointly developed with the U.S. EPA, and over 170 papers in areas ranging from coal liquefaction and heavy oil chemistry to the chemistry of urban atmospheres.

Urban air quality and the development of materials for environmental education have been the primary focus of his work for the past decade. Dr. Allen was a lead investigator for the first two Texas Air Quality Studies, which involved hundreds of researchers from around the world, and which have had a substantial impact on the direction of air quality policies in Texas. He has also developed environmental education materials for engineering curricula and for the core curriculum of the University of Texas. His quality work was recognized by the National Science Foundation through the Presidential Young Investigator Award, the AT&T Foundation through an Industrial Ecology Fellowship, the American Institute of Chemical Engineers through the Cecil Award for contributions to environmental engineering, and the State of Texas through the Governor’s Environmental Excellence Award.

Dr. Allen received his B.S. degree in Chemi-cal Engineering, with distinction, from Cornell University in 1979; and his M.S. and Ph.D. degrees in Chemical Engineering from the California Institute of Technology in 1981 and 1983, respectively. He has held visiting faculty appointments at the California Institute of Technology, the University of California, Santa Barbara, and the Department of Energy.


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