Technical energy regulations are an important measure to reach climate targets. However, with recent developments in new technologies (such as decentralized energy systems, urban energy systems, energy storage systems, etc.) many different options and combination of measures exist to decarbonize the building stock, which requires an update of current versions of technical energy regulations.

The aim of this work is to investigate the optimal transformation strategies for buildings and districts to reach CO₂ emission reduction targets for the Swiss building stock, to support policies and decision makers in developing new energy regulations for the future.

A simulation approach is developed, which combines clustering methods, to define representative buildings and districts, with multi-objective optimization to investigate the optimal set of building and district measures to minimize costs and CO₂ emissions. Results at building level show that the most economical measures for reaching emission targets for the future include roof retrofitting and window replacement together with PV installation. In terms of heating systems, biomass or heat pumps seem to be the most favourable option. The analysis of district archetypes shows that district level solutions are mainly applicable to urban communities, whereas building level solutions are clearly the optimal solution for rural areas.