Comparative LCA study of different timber and mineral buildings and calculation method for substitution factors on building level

This article describes the approach of performing comparative life cycle assessments (LCA) of residential buildings with different building constructions according to the actual standards EN 15978:2012. Based on the LCA calculations of the different constructions - timber and mineral - substitution factors on building level are calculated. Substitution factors describe the greenhouse gas (GHG) reduction potential that occurs when using timber instead of mineral material in building construction. The method on how to assess substitution factors on building level is demonstrated. Results show that the substitution factors for the construction of single/two-family-houses range between 0.35 and 0.56 for LCA and between 0.09 and 0.48 for multi-story residential buildings based on kg CO2 eq per m2 gross external area (GEA), which means that there is a positive GHG reduction potential when building with timber instead of using mineral materials. Projections on national scale regarding GHG reduction potential in the building sector can be done on the basis of these values.