Buildings in municipal climate change mitigation strategies : towards life cycle thinking

Sammanfattning: Fulfilling climate targets requires ambitious changes. The building sector is a large contributor to emissions of greenhouse gases (GHG), but also offers opportunities for climate change impact reductions. This thesis aims at supporting strategic decisions to reach climate change mitigation targets in the building sector, based on knowledge about what factors contribute significantly to climate impact from buildings in a life cycle perspective and how practitioners can influence these factors. More specifically, a first point of investigation concerns what aspects play a key importance in buildings’ climate impact, and what climate change mitigation strategies for the building sector should focus on. A quantitative analysis of backcasting scenarios for 2050 was performed using a spreadsheet model to estimate GHG emissions for the building sector. The parameters were adjusted to ensure that a GHG emission quota was reached in every scenario. This provided an illustration of four very different ways the building sector could contribute to the fulfillment of a global climate change mitigation target. The results were used to discuss what aspects of buildings were particularly important for target fulfillment. These aspects include a low-carbon energy mix, a reduction of GHG emissions from construction materials and an optimized use of space. A second point of investigation concerns how municipalities can influence practices through the use of environmental requirements in construction, in particular requirements based on a life cycle approach. A survey of Swedish municipalities was used to assess their current practices and knowledge level regarding mitigating climate change impact from construction, as well as the influence of a municipality’s size on these practices. It was followed up by semi-structured interviews investigating barriers to the use of environmental requirements in construction. Barriers were identified regarding in-house skills, access to data, resources, ambiguities regarding the law and guidance from national authorities. A stepwise strategy was suggested to overcome these barriers and successfully implement environmental requirements. Therefore, the thesis as a whole provides insight on how municipalities could use environmental requirements in construction to influence current practices in the building sector, so that the changes needed to fulfill the 1.5℃ target are implemented.