Using absolute environmental sustainability assessment and mid-to-endpoint modeling to identify the most relevant impact categories to include in a building LCA

The building industry has lately increased its focus on its environmental impacts and the assessment of these through life-cycle assessment (LCA). While there has been a strong emphasis on assessing climate change impacts, other environmental impacts have often been neglected. This study identifies the most relevant midpoint impact categories to include in LCAs on buildings through two complementary approaches. Both approaches assess relevance based on the severity of impacts: absolute environmental sustainability assessment (AESA) and mid-to-endpoint (MtE) contribution analysis. The approaches are applied to 40 Danish residential buildings covering 370,000 m². For the AESA approach, impact categories for which case buildings exceeded their allocated carrying capacity were considered relevant, while the impact categories contributing most to endpoint damages were considered relevant for the MtE approach. The characterization factors (CF) and allocation principles of the study were tested in a robustness analysis. Climate change, land use, and fine particulate matter were relevant according to both approaches and showed a high robustness towards changes in the set of CFs and the allocation principle. Freshwater ecotoxicity, freshwater eutrophication, human carcinogenic toxicity, and mineral use were less robust considering the choice of LCIA methods and allocation principles. Our approach aims to help the building industry finding a middle ground between only reporting LCA results for climate change, which could lead to burden-shifting, and systematically reporting LCA results for all midpoint impact categories, which could lead to decision paralysis.