Retrofitting a building to passive house level: A life cycle carbon balance

The building sector is one of the major contributors to global carbon emission. Energy retrofit of existing buildings reduces CO2-eq emission in the operation phase but typically entails further emissions from the production, maintenance and disposal of the materials used for the retrofitting (non-operation CO2-eq emission). This study analyses the life cycle carbon balance of a building retrofitted to passive house level, considering two alternative standards applicable in Sweden. The study considers the implications of using different building materials for thermal insulation, building façade and windows of the retrofitted building. It also considers different electricity production scenarios, assuming standalone production with fossil coal, fossil gas, and a mix of wind and biomass. Our results show that the operation CO2-eq emission decreases by between 50 and 82% in the retrofitted building depending on the passive house standard, with minor deviations between the electricity scenarios. The non-operation CO2-eq emission accounts for between 4 and 25% of the operation CO2-eq savings depending on the passive house standard and material option. Deviations between material options are increasingly reduced when assuming fossil gas and wind/biomass for electricity production instead of fossil coal. A careful selection of materials can reduce the net CO2-eq savings by up to 68%, especially when using wood material.