Materialval för klimatvänligt byggande : Fallstudie av ETC Bygg AB:s pilotprojekt "Klimatpositiva hyreshus av trä" i Västerås

Sammanfattning: Purpose: The aim of this study was to investigate the climate impact of building materials used in the pilot project “Klimatpositiva hyreshus av trä i Västerås” by ETC Bygg. The purpose also included studying the demands on building materials when it comes to climate impact as well as the challenges of building with more climate friendly materials. Method: This study is based on a literature study and case study of the building materials used in the pilot project “Klimatpositiva hyreshus av trä i Västerås”. Results: By using the climate-enhanced concrete instead of conventional concrete in the building foundation, the climate impact is reduced by 45%. If the storage of carbon in wood is taken into account, the wooden based materials used in the buildings are considered the most climate friendly. Also, when carbon storage is not taken into account, the wooden frame of cross-laminated timber used in studied buildings results in lower climate impact than conventional concrete. In most cases even better than climate enhanced concrete. The wooden fibre insulation used has one of the lowest climate impact, together with cellulose, when the carbon storage is considered. Data of its impact, without carbon storage, is missing. Literature shows that insulation of cellulose from recycled material, like the one used in the studied buildings, has among the lowest climate impact, whether the storage of carbon is included or not. However, data of the specific cellulose used in the buildings is missing. The results also show that there is possible to make more climate friendly options within a group of materials. In the studied project there has been no greater challenges when using selected materials. Currently there are no demands considering greenhouse gas emissions from building materials. Although, there is regulation in the law which aims at a sustainable development and there is national environmental goals and goals for the building sector to lower the climate impact. Conclusions: By using climate enhanced concrete in the foundation and wood as frame material and insulation, the studied buildings have reduced their climate impact in comparison to usage of more conventional building materials during the product stage. Some major challenges with used materials in the studied buildings do not appear to have existed, which differs from what is described in the literature, where several challenges are mentioned. By using building materials with lower climate impact, it can be considered a way to work towards the goals and regulations considering sustainable development.