Life cycle assessment and life cycle cost analysis of a single-family house

Sammanfattning: The building industry is responsible for 35% of final energy use and 38% of CO2 emissions at a global level. The European Union aims to reduce CO2 emissions in the building industry by up to 90% by the year 2050. Therefore, it is important to consider the environmental impacts buildings have. The purpose of this thesis was to investigate the environmental impacts and costs of a single-family house in Sweden. In the study, the life cycle assessment (LCA) and the life cycle cost (LCC) methods have been used by following the “cradle to grave” life cycle perspective. This study shows a significant reduction of global warming potential (GWP), primary energy (PE) use and costs when the lifespan of the house is shifted from 50 to 100 years. The findings illustrate a total decrease in LCA outcome, of GWP to 27% and PE to 18%. Considering the total LCC outcome, when the discount rate increases from 3% to 5% and then 7%, the total costs decrease significantly (60%, 85% to 95%). The embodied carbon, PE use and costs from the production stage/construction stage are significantly reduced, while the maintenance/replacement stage displays the opposite trend. Operational energy use, water consumption and end-of-life, however, remain largely unchanged. Furthermore, the findings emphasize the importance of using wood-based building materials due to its lower carbon-intensive manufacturing process compared to non-wood choices.  The results of the LCA and LCC were systematically studied and are presented visually. Low carbon and cost-effective materials and installations have to be identified in the early stage of a building design so that the appropriate investment choices can be made that will reduce a building’s total environmental and economic impact in the long run. Findings from this thesis provide a greater understanding of the environmental and economic impacts that are relevant for decision-makers when building single-family houses.