Buildings LCA methodology, focus on the climate impact of maintenance and replacement processes

University essay from KTH/Hållbar utveckling, miljövetenskap och teknik

Abstract: The Swedish government introduced on Monday 3rd of January 2022, a new bill to promote buildings’ sustainability. Assigned by the government, the bill was developed by the Swedish National Board of Housing, Building and Planning (Boverket). When applying the Life Cycle Assessment (LCA) framework, developers must now declare the greenhouse gas emissions resulting from the production and construction processes of their proposed construction, using the Global Warming Potential (GWP) indicator. Boverket is currently planning for the climate declaration’s evolution regarding limit values, building components, and the life cycle stages considered. Use and end-of life stages are facing major challenges as they are prone to high uncertainty, especially due to projections into the future. Currently, no International, European, nor national guidelines or norms agree on calculation methods for maintenance and replacement processes. However, methodological choices related to system boundaries, as well as maintenance and replacement needs and frequencies, significantly affect these calculation results.  This master thesis, focusing on maintenance and replacement processes LCA calculations, is a follow up of KTH research. Mandated by Boverket, it developed a national database for buildings’ components and reference values for production and construction processes. This study uses the same sample of buildings, representative of recent Swedish buildings stock for several functions, such as schools, apartment buildings, and offices. In line with Boverket’s plan, a method of calculation is developed based on literature for the maintenance and replacement processes of buildings’ roofs and façades. The relevance of considering these processes in buildings’ climate declarations is addressed. In addition, this study investigates methodological and practical challenges in a Swedish context. Specifically, it assesses the effect of calculation method on the consideration of replacement components’ environmental impact and service lives. Practical difficulties regarding implementation of these LCA processes are also discussed.  This study concludes on the relevance of considering replacement and maintenance processes in buildings’ climate declarations to avoid misleading conclusions over sustainable buildings designs. The influence of methodological choices is confirmed, and the need for harmonisation for clear definitions and guidelines for maintenance and replacement processes is emphasised. The study also identifies practical data requirements and reflects on the requirement of LCA internalization in the construction sector, from the early steps of buildings’ conception and the inclusion of all stakeholders, especially from industry. 

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