life cycle assessment - texas architecture - seminar in sustainable architecture ... natural gas...

csdCenter for Sustainable Development

Life Cycle Assessment

Meghan Kleon

Werner LangInstructor

UTSoA - Seminar in Sustainable Architecture

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Meghan Kleon

Life Cycle Assessment (LCA) is a tool used to evaluate both the direct and indirect environmental impact of the entire lifecycle of a product, system, process or building.1 Unlike Life Cycle Costing, which is only con-cerned with economic impact over the life of a product, LCA explicitly addresses environmental costs. When examining a particular mate-rial, LCA analyzes the environmental impact at different stages through the life of the product, often referred to as the “cradle-to-grave” approach (or “cradle-to-cradle” if the materials are able to be entirely recycled).2 Typi-cally a life cycle assessment includes an examination of the raw material acquisition, manufacturing process and packaging, transportation, instal-lation or use, reuse and maintenance and operating impacts, and disposal or recycling of a material or system.3

By evaluating a material’s entire life-cycle instead of examining just one phase of its life-cycle (for example, its use or its disposal), LCA provides

a more holistic view of the environ-mental impacts of a given product or system. Consequently, LCA gives decision-makers a more balanced view of the true environmental im-pact of a material, and helps prevent the shifting of negative environmen-tal effects from one life cycle stage to another, allowing them to make more sustainable design decisions.4 One often cited example of shifting nega-tive environmental impacts is the comparison between compact fluo-rescent light bulbs (CFL) and incan-descent bulbs. CFLs generally use about 75% less energy throughout their operating life than a comperable incandescent light bulb, and lasts up to 10 times longer, but they also contain small amounts of mercury – approximately 4 milligrams per bulb. Considering only the disposal phase of the light bulbs, it might appear that incandescent bulbs are a better environmental choice because they do not contain mercury, a potentially hazardous material. Looking only at the operating energy, the compact

Fig. 00 Building life cycle phases: extraction, manufacturing, construction, occupancy, deconstruction, reuse


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fluorescent has far less of an envi-ronmental impact. Examining the phases of the life cycle individually, it is difficult to make a decision regard-ing which bulb to use. However, when a full LCA is performed, the benefits of using compact fluores-cents (energy saved) far outweigh the negatives (the possibility of mercury being released at disposal). The reduction in energy use equates to a reduction of mercury produced by power plants producing that energy that far outweighs the small amount of mercury in the bulb.5

The methodology of a life cycle as-sessment consists of four phases:- the goal and scope definition- inventory analysis- impact assessment- and interpretation and analysis.6

During goal definition and scoping, the product is defined and described, and the context and boundaries of the assessment are established, along with the environmental impacts to be evaluated. Next, during the inventory analysis, the environmen-tal, energy and resource impacts are identified and quantified.7 During the impact assessment phase of a life cycle assessment the results of the inventory analysis are correlated to overall environmental and health indicators so that they can be more easily compared. Finally, in the in-terpretation and analysis, the results are evaluated and used to inform design decisions with reduced en-vironmental impacts, paying careful attention to the results and keeping in mind the boundaries, scope and assumptions from the first step of

the assessment.8 Dr. David T. Allen notes that it is crucial to take into account that “the LCA process will require estimates and assumptions, which will likely include making value judgments. Any such estimates, assumptions, and value judgments should be communicated in the final results and considered when drawing conclusions.”9 In addition, it is worth noting that a LCA does not consider cost or performance, or assess the social or cultural impact of a product and should not be relied upon as the sole criteria by which a material or system is evaluated.10

There are a variety of Life Cycle Assessment tools available,11 each of which relies on its own unique data set. In addition, most LCA tools focus on a particular part of the life cycle, and have been designed to evaluate a particular category of building.12 Sometimes the use of several LCA tools may be neces-sary to achieve the desired results, particularly when evaluating multiple products or systems.

When applying LCA methodology to analyze an entire building, it is often beneficial to use a combination of LCA tools that can be tailored to meet the objective of the assess-ment. Different tools may also be re-quired based on the various materi-als, systems, or parts of the life cycle of the building being evaluated.13

Although the concept of LCA is quite simple, the actual LCA calculations can be very complex and regardless of the LCA tool employed, “problems [can] arise concerning the quality, consistency, and availability of data on products and processes; the methods used to compile inventories; and especially the assumptions and

Fig. 01 Life Cycle of Building Products


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systems used to translate inputs and outputs into measures of environ-mental impact.”14 All of these inputs must be taken into consideration both when selecting an LCA tool and then when evaluating and interpret-ing the results.

Embodied Energy

Embodied energy, sometimes called embedded energy, is defined as “the energy required to produce a product (from extraction of raw materials, through manufacturing, and including transportation to the point of use); expressed as Btu/lb or kJ/kg.”15 In other words, it is the energy embod-ied in the physical structure of the building, the “as built” energy of the building.16 (The life-cycle embodied energy of a material, in contrast, includes not only the construction or manufacturing, but also the energy required for maintenance, repair and demolition or disposal17).

One of the primary environmental im-pacts of a building during its lifecycle is the energy that it consumes during the extraction and manufacturing of building materials, the building construction, operations and main-tenance, and disposal. According to the U.S. Green Building Council, buildings are responsible for 72% of the electricity consumption and 39% of the energy use in the United States today.18

Studies show that most of the energy consumed during the lifetime of a particular building is operating en-ergy, and that the energy consumed in the production of the building and building materials generally only accounts for 10-15% of total energy use.19 However, as more attention is paid to reducing the operating en-

ergy and buildings become more en-ergy efficient and have longer life cy-cles, the embodied energy becomes a much more significant factor in the total energy consumed by a build-ing over its lifetime (see Figure 02). Figure 02 illustrates the significant impact of an high efficiency building’s embodied energy. For low-efficiency buildings, the embodied energy represents just a small portion of the cumulative energy consumed by the building. After 10 years, the energy to operate the low-efficiency building has surpassed the energy embedded in it. In comparison, the embodied energy in a high-efficiency building the building is much higher than the cumulative operating energy until a high efficiency building is almost 60 years old. Thus, as efficiency of buildings increases, the embod-ied energy becomes a much more significant portion of the building’s energy consumption - and in order to achieve truly “zero-energy” build-ings, the issue of the initial embodied

energy must be addressed.

A study conducted in Sweden came to the same conclusion, finding that embodied energy accounts for about 40% of the energy consumed dur-ing the lifetime (assumed to be 50 years) of low-energy (high-efficiency) buildings.20 Therefore, in addition to reducing the energy consumed dur-ing the operation phase of a building through efficiency measures and sustainable design, it is also critical that designers begin reducing the embodied energy consumed during the construction of a building.

In addition to the initial embodied energy, it is also possible to calculate the recurring embodied energy in a structure or material. The recurring embodied energy is defined as the “non-renewable energy consumed to maintain, repair, restore, refurbish or replace materials, components or systems during the life of the build-ing.”21 Just as different materials and

Fig. 02 Energy Use in Buildings: Changing relationship between embodied and operating energy consumption over time


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building systems have different initial embodied energy, they also have dif-fering recurring embodied energy re-quirements. Figure 03 demonstrates the initial and recurring embodied energy of different systems and aspects of a wood structure building over a 100 year lifespan. The struc-ture of a building, which requires a large initial investment of embodied energy, requires very little ongoing investment - consequently, design-ers should pay particular attention to the embodied energy of structural components. Finishes, which wear out or go out of fashion, have a lower initial investment of embodied energy, but they have a large recur-ring embodied energy due to much more frequent replacement, meaning that their embodied energy should be considered throughout the lifecycle of the entire building.

Figure 03 demonstrates the need to view not only materials and systems, but also embodied energy, in the

context of an entire life cycle, and not just at one stage of the building’s life.

Case Study: Experimental Science and Norman Hackerman Science Buildings, University of Texas at Austin

The Experimental Science Building (ESB) was constructed in 1950 at the corner of 24th Street and Speedway on the University of Texas campus in Austin, Texas. At the time of its completion it was one of the larg-est scientific research buildings in the United States, with 64 laborato-ries and 39 teaching labs. Over its lifetime the five-story structure was home to the biochemistry, chemistry, bacteriology, zoology and microbiol-ogy departments.22

Following renovations of the build-ing in the 1980s, some systems improvements were made to the building in 2005 after workers found corroded gas lines in the base-

ment, and the building was found to be in violation of fire code.23 Gar-land Waldrop, Fire Marshal for the University, stated that the building lacked “sufficient emergency light-ing, a fire sprinkler system” and had “unprotected vertical openings,” all of which were major code violations. In addition, ongoing problems with the natural gas piping made it impossible for faculty and students to conduct research and experiments.24 Due to the large number of violations, and the inadequacy of the facilities for modern scientific research, the University began to pursue either the complete renovation or the replace-ment of the Experimental Science Building.

Ultimately, the decision was made to demolish the building and build a re-placement in the same location. Es-timates showed that the renovation of ESB would cost more than build-ing an entirely new structure,25 and UT faculty, staff and administration expressed concerns about not only the cost and viability of a complete renovation, but also how the build-ing’s historical significance might complicate a renovation project.26

According to Dr. Peter Riley, Associ-ate Dean for the College of Natural Sciences at UT Austin, the primary factor in making the decision to re-place rather than renovate the ESB was the floor-to-floor height. At 12 feet, the height did not allow for the ducts that would have been required for adequate air handling in a labora-tory building, due to the number of fume hoods needed to perform chemistry research and experiments. Bringing ESB up to current build-ing code and to the requirements of a modern research building would have meant losing almost an entire

Fig. 03 Comparison of Initial to Recurring Embodied Energy for Wood Structure Building Over a 100-Year Lifespan


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floor in order to accommodate the increased ventilation and mechanical needs. In addition, at 210,00 square feet the Experimental Science build-ing was no longer large enough to hold all of the labs, classrooms and departmental offices required by the departments housed in the build-ing. Dr. Riley writes that “by 2007, I had participated in three “renova-tion design teams” for the old ESB over the past decade. Each one concluded that it was inefficient to renovate the old ESB.”27 Demolition of the Experimental Science Building began in 2008. Total project costs for the demolition of ESB and construc-tion of a new building at the site are estimated at $175 million, with $2 million for demolition and $125 mil-lion for construction of the replace-ment building. 28

In order to prevent the waste of materials and a loss of the embodied energy in those building materials, 90% of the material from the de-molition was diverted from landfills, including steel reinforcing bars, pipes and ductwork, brick, clay tile, interior fixtures and concrete. Over 80% of the construction waste materials will be diverted from landfills. Diverting both construction waste and build-ing materials from landfills saves not only landfill space, but also cap-tures some of the embodied energy embedded in those materials, which would otherwise be lost.

The Experimental Science Build-ing will be replaced in 2010 by the Norman Hackerman Science (NHS) Building, named for a former uni-versity president and Chair of the Chemistry Department. At six stories and 287,000 square feet, the Nor-man Hackerman Science Building will add significant new research

space for neuroscience, chemistry and teaching labs. NHS was de-signed to take advantage of very limited site footprint while still adding 90,000 square feet for research, and to allow for departmental growth in the future. The building, designed by Evan Taniguchi and CO Archi-tects, will meet Labs21 performance guidelines for energy efficiency and sustainability. (The Labs21 program seeks to reduce the large amount of energy and water per square foot that lab facilities consume due to intensive ventilation requirements and other health and safety con-cerns. “The primary guiding prin-ciple of the Labs21 approach is that improving the energy efficiency and environmental performance of these facilities requires examining the entire facility from a ‘whole building’ perspective... that allows owners to improve the efficiency of the entire facility, rather than focusing on spe-cific building components.”)29 The project is also seeking LEED silver certification under LEED for New Construction and Major Renovations 2.2. The design adheres to the UT Austin Campus Master Plan, and will feature a limestone base, brick body and terra-cotta roof.30

According to Project Manager Brian Wittmayer, although the design for NHS does not explicitly address and correct for some of the issues that made the ESB too difficult and expensive to renovate (poor floor-to-floor height, reduced column spacing), its reliance on Labs21 and LEED guidelines will allow the new building to be more easily adapted in the future.

To minimize the life cycle impact of its buildings, it would be prudent for the university to more explicitly

Fig. 04 Experimental Science Building Entrance, 2008

Fig. 05 Experimental Science Building During Demolition, 2008


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consider designing for adaptation or, in the case of buildings with rapidly changing requirements (like lab buildings) for easy deconstruction or reconfiguration. As buildings on the UT campus become more efficient and consume less operating energy, the embodied energy in the buildings will become increasingly important. Reducing the embodied energy begins not only with considering the life cycle impact of building materials, but also ways to extend the useful life of each building, which will in turn minimize the negative impact of the embodied energy of each building.

Notes

1. Allen, David T. “Eco-Conscious Architecture Through Life Cycle Assessment for Buildings” transcribed by Elena Rivera, 3.


3. Scientific Applications International Corporation, 2006. Life Cycle Assessment: Principles and Practice, produced for the U.S. Environmental Protection Agency through its Office of Research and Development, www.epa.gov/NRMRL/lcaccess/pdfs/600r06060.pdf


5. EnergyStar, “Compact Fluorescent Light Bulbs (CFLs) and Mercury,” http://www.ener-gystar.gov/index.cfm?c=cfls.pr_cfls_mercury.

6. Allen, David T. “Eco-Conscious Architecture Through Life Cycle Assessment for Build-ings” transcribed by Elena Rivera, 2. For a more detailed explanation of each of the steps in a life cycle assessment methodology, see United States Environmental Protection Agency, Life Cycle Assessment: Principles and Practice

7. Scientific Applications International Corporation, 2006. Life Cycle Assessment: Principles and Practice, produced for the U.S.

Environmental Protection Agency through its Office of Research and Development, www.epa.gov/NRMRL/lcaccess/pdfs/600r06060.pdf.

8. Rivera, Elena. “Eco-Conscious Architecture Through Life Cycle Assessment for Buildings” based on a presentation by Dr. David T. Allen from Reader, 6-7.



11. For more detailed information on specific LCA tools and LCA databases, see Allen 2009 and Haapio, Appu and Pertti Viitaniemi, 2008. “A critical review of building environmental assessment tools,” Environmental Impact As-sessment Review 28, no. 7: 469-482.

12. Allen, David T. “Eco-Conscious Architec-ture Through Life Cycle Assessment for Build-ings” transcribed by Elena Rivera,, 8.

13. Allen, David T. “Eco-Conscious Architec-ture Through Life Cycle Assessment for Build-ings” transcribed by Elena Rivera, 4.

14. Malin, Nadav, 2002. “Life Cycle Assess-ment for Buildings: Seeking the Holy Grail” Environmental Building News 11 no. 3, March: 3.

15. Kwok, Alison G. and Walter T. Grondzik, 2007. The Green Studio Handbook: Envi-ronmental Strategies for Schematic Design, Burlington, MA: Architectura Press, 340.

16. Mumma, Tracy. “Reducing the Em-bodied Energy of Buildings” Home Energy Magazine January/February, http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/95/950109.html.

17. Mumma, Tracy. “Reducing the Em-bodied Energy of Buildings” Home Energy Magazine January/February, http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/95/950109.html.

18. U.S. Green Building Council, “Green Build-ing Research,” http://www.usgbc.org/Display-Page.aspx?CMSPageID=1718

19. Thormark, Catarina, 2002. “A low energy building in a life cycle—its embodied energy, energy need for operation and recycling po-tential” Building and Environment 37: 429.

20. Thormark, Catarina, 2002. “A low energy building in a life cycle—its embodied energy, energy need for operation and recycling po-tential” Building and Environment 37: 434.

21. Canadian Architect. Measures of Sus-tainability: Embodied Energy, http://www.canadianarchitect.com/asf/perspectives_sus-tainibility/measures_of_sustainablity/mea-sures_of_sustainablity_embodied.htm

22. Berry, Margaret Catherine, 1993. Brick by golden brick : a history of campus buildings at the University of Texas at Austin, 1883-1993, Austin, Texas: LBCo., 70-71.

23. Callahan, Kevin M., 2005. “ESB needs major renovations to pass fire codes,” The Daily Texan, 22 March, http://www.dailytexa-nonline.com/2.4489/esb-needs-major-renova-tions-to-pass-fire-codes-1.980216.48. Dechant, Larry, 2008. “Experimental Sci-ence Building to be demolished,” The Daily Texan, 17 January, http://www.dailytexanon-line.com/university/experimental-science-building-to-be-demolished-1.951681.

24. Dechant, Larry, 2008. “Experimental Sci-ence Building to be demolished,” The Daily Texan, 17 January, http://www.dailytexanon-line.com/university/experimental-science-building-to-be-demolished-1.951681.

25. Callahan, Kevin M., 2005. “ESB needs major renovations to pass fire codes,” The Daily Texan, 22 March, http://www.dailytexa-nonline.com/2.4489/esb-needs-major-renova-tions-to-pass-fire-codes-1.980216.

26. Riley, Peter. “Norman Hackerman Build-ing,” E-mail to Meghan Feran Kleon. 10 August 2009.

27. Dechant, Larry, 2008. “Experimental Sci-ence Building to be demolished,” The Daily Texan, 17 January, http://www.dailytexanon-line.com/university/experimental-science-building-to-be-demolished-1.951681.

28. Labs 21. About Labs 21. http://www.labs21century.gov/about/index.htm

29. Dechant, Larry, 2008. “Experimental Sci-ence Building to be demolished,” The Daily Texan, 17 January, http://www.dailytexanon-line.com/university/experimentalscience-build-ing-to-be demolished-1.951681.


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Figures

Figure 00: Created by Alexer Taganas

Figure 01: Athena Institute. LCA Model, http://www.athenasmi.org/about/lcaModel.html

Figure 02: MIT Energy Initiative. Innovative buildings: Prudent use of energy and materi-als, http://web.mit.edu/mitei/research/spot-lights/innovative-buildings.html

Figure 03: Canadian Architect. Measures of Sustainability: Embodied Energy, http://www.canadianarchitect.com/asf/perspectives_sus-tainibility/measures_of_sustainablity/mea-sures_of_sustainablity_embodied.htm

Figure 04: The University of Texas at Austin. Experimental Science Building, http://www.utexas.edu/maps/main/buildings/esb.html

Figure 05: Flickr User GoodEvilGenius, http://www.flickr.com/photos/goodev-ilgenius/2578653493/sizes/o/in/set-72157594535082842/

References

Athena Institute: http://www.athenasmi.org/

Energy Information Administration: http://www.eia.doe.gov/

Life Cycle Building Challenge, http://lifecycle-building.org

U.S. Department of Agriculture, Forest Eco-nomics and Policy, http://www.srs.fs.usda.gov/econ/default.htm

U.S. Environmental Protection Agency: http://www.epa.gov/.

United States Environmental Protection Agen-cy (EPA), Lifecycle Construction Resource Guide, February 2008

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