Critical review of life cycle assessment (LCA) for the built environment at the neighborhood scale

Abstract

The built environment is recognized as a major hotspot of resource use and environmental impacts. Life cycle assessment (LCA) has been increasingly used to assess the environmental impacts of construction products and buildings during the last 25 years. A new trend stems in the application of LCA to larger systems such as urban islets or neighborhoods. This review aims at compiling all papers related to LCA of the built environment at the neighborhood scale. A focus is carried out on 21 existing case studies which are analyzed according to criteria derived from the four phases of LCA international standards. It sums up current practices in terms of goal and scope definition, life cycle inventory (LCI) and life cycle impact assessment (LCIA). The results show that the case studies pursue different goals. They are either conducted on existing or model neighborhoods with an aim at building knowledge to feed urban policy making. Or they are conducted on actual urban development projects for eco-design purpose. Studies are based on different scopes, resulting in the selection of different functional units and system boundaries. A comparison of data collection strategies is provided as well as a comparison of LCIA results for cumulative energy demand and greenhouse gases emissions. Methodological challenges and research needs in the field of application of LCA to neighborhood scale assessment are identified, such as the definition of the functional unit and the need for contextualization methodologies aligned with data availability at the design stages of a neighborhood development project.