Building rehabilitation life cycle assessment methodology–state of the art

Abstract

Life cycle assessment (LCA) is recognized as a key method of assessing the potential environmental impacts of product systems in the building sector. Applied to rehabilitated buildings, the LCA methodology generally aims at assessing and comparing different scenarios regarding either rehabilitation only or rehabilitation plus new building while using several methodological approaches. The present study aims at establishing the state of the art of building rehabilitation LCA methodology used in case studies. By means of a literature review, 41 LCA studies are analyzed according to key methodological aspects and compared with rules from the ISO 21931-1, the EN 15978, and the ISO 14044 standards, and from the EeBGuide guidance document. The reviewed studies, while featuring a variety of methodological choices, display certain trends. With respect to the type of assessment, 80% of the studies compare only rehabilitated buildings scenarios, and did not consider a new building scenario. About half of the studies reported adhering to either a standard (ISO 14044 or EN 15978) or a guidance document (EeBGuide or Annex 56). The unit of reference is always based on a surface unit—63% use 1 m2 or 1 m2/yr. With regard to the reference service period, 80% of the studies use 50 or 60 years. All the studies except one consider the material/product manufacturing and the operational energy of the building—71% include four other life cycle modules (A-C) and 41% consider reuse/recycling (D). With regard to the impact categories considered, 71% of the LCA studies include three to eight midpoint impact categories–or endpoint impact categories–and all of them consider the global warming potential and the cumulative energy demand. Finally, about half of the studies (46%) consider the interpretation stage. Based on the present analysis, methodological challenges are pointed out, recommendations for methodological improvements are proposed and future research pathways are suggested.