Life cycle assessment (LCA) has been used for decades to study the environmental impacts of the built environment. This study extends work in this area by completing an LCA of the cumulative energy demand (CED) and global warming potential (GWP) of low, mid and high-rise multi-family dwellings. Using a hybrid LCA, this study finds that the CED and GWP for low, mid and high-rise multi-family residences increases from 37, 39, to 42 GJ/m2, and 3.6, 3.8, and 4 tCO2eq/m2 on average, respectively. As with previous studies, the operation phase dominates total life cycle energy, but with smaller share of 77% to 87%. A follow-up study examines how uncertainty in the energy intensity of materials might affect a building LCA. The exploration led to development of a knowledge-based bounding approach to mitigate uncertainty. Knowledge-based bounding maps knowledge of a product, such as country of origin or recycled content, to numerical uncertainty bounds. Gathering additional information about the product in question can shrink these bounds and, through an iterative process, reduce uncertainty until the goals of an LCA are met. Developing knowledge-based bounds for steel, this study finds that if steel type, recycled content and country of origin are all unknown, the life cycle carbon dioxide equivalent emissions of steel can vary from .7 to 5.9 kg tCO2eq per kg of steel. In contrast, with knowledge that the steel is un-alloyed, and, has a 64-100% recycled content, uncertainty bounds are reduced to .8-1.4 kg tCO2eq/kg steel. These two bounds are applied in life cycle assessment of concrete and steel framed buildings. The 0.7 to 5.9 kg tCO2eq emissions per kg of steel bound leads to ranges for the life cycle emissions too wide to distinguish the preferability of steel and concrete framed buildings. However, the lower bounds, 0.8-1.4 tCO2eq/kg of steel, shows unambiguously that steel-framed buildings have lower CO2 emissions.
Library of Congress Subject Headings
Building materials--Environmental aspects; Life cycle costing; Apartment houses--Environmental aspects; Cumulative effects assessment (Environmental assessment)
Department, Program, or Center
Bawden, Kimberly, "Hybrid life cycle assessment of low, mid and high-rise multi-family dwellings with development of knowledge-based uncertainty bounds" (2013). Thesis. Rochester Institute of Technology. Accessed from
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