Embodied greenhouse gas emissions in structural materials for the German residential building stock - Quantification and mitigation scenarios

Embodied emissions in construction materials make a relevant contribution to carbon emissions worldwide. While this has been broadly recognised, only little attention has been paid to the role of load-bearing structures in this regard, and if so, mainly limited to assessments of individual structures. For analysing the global warming impact of engineering structures in a wider context, dynamic material flow analysis is deployed in this study. The future stocks and flows of structural materials and their associated embodied emissions in German residential buildings are quantified based on a mass-balance consistent multi-layer model, which relates the stocks in use, their inputs, outputs and determinants, such as the building lifetime, the population or the useful building floor area per capita. A scenario analysis under combination of different emission mitigation measures is performed, among them a gradual replacement of the comparatively large masonry structure stock share by timber structures, and a general downsizing of structural material quantities. The results show that when applied to a realistic extent, such measures could contribute with about 4% to 8% to the German average target mitigation rate required for achieving emission neutrality in 2045.