A Systematic Review of Carbon and Impacts Beyond Carbon of Life-Cycle Assessment of Buildings

Abstract

Buildings and their supply chains are among the most significant drivers of climate change and the deterioration of ecosystem health. Life-Cycle Assessment (LCA) is a framework for quantifying environmental impacts, now commonly used for buildings and recently implemented in EU and UK legislation for Whole Life Carbon (WLC) analyses. The regulatory focus on carbon reflects the narrow focus governing the area of sustainability and the difficulty in obtaining reliable and realistic LCA results for impacts beyond carbon (i.e., all remaining impacts of the LCA protocol, such as land use, eutrophication, and water use) that make sense when benchmarked against other studies. This study identifies knowledge gaps by comparing both carbon and beyond-carbon results of case studies obtained through a systematic approach. The innovative aspect of this study is twofold. Firstly, it analyzes the magnitude of environmental impacts in previously published studies. Secondly, it identifies the key challenges in benchmarking that arise from the principle that most impacts beyond carbon are calculated for specific geographical zones. Results identified a strong focus on carbon, indicating that impacts beyond carbon are significantly underexplored. This might become problematic, as evidence shows intensifying pressure on impacts beyond carbon when decisions are taken solely on the basis of carbon. Statistical analyses support that embodied modules are significant contributors to life-cycle Ozone Depletion (OD), Terrestrial Acidification (TA), Marine Eutrophication (MEU), and Photochemical Oxidant Formation (POF). Still, operational modules contribute more to life-cycle carbon. Although previous research emphasized that differences in scope, system boundaries, life-cycle modules, and lifespans affect the potential for benchmarking, this study proposes two more aspects that make benchmarking challenging. These are (a) regionalized Characterization Factors (CFs) and (b) localized manufacturing processes that lead to results that are reflective of specific geographical zones. Therefore, selecting the appropriate candidates for comparison from a pool of studies is essential, as similarities must be satisfied not only at the building level but also at the level of localized processes and regionalized CFs. Finally, the identified knowledge gaps warrant further research to determine whether benchmarking remains valid in the context of regionalized impacts.