The decarbonization of buildings is highlighted as a priority to achieve the EU's long-term energy and climate goals. In this work, the Swiss energy performance certificate database is used to assess the current state of the residential building stock in Switzerland and its characteristics in terms of greenhouse gas (GHG) emissions. The GHG emissions in kg CO2-eq related to space heating and domestic hot water is calculated from the final energy used of each building type. Then, a sub-sample of buildings that have been retrofitted in recent years is established to analyse the type of renovation performed, its depth, and the GHG reduction achieved. The results suggest that energy retrofitting has mainly focussed on energy savings (leading to an overall GHG savings by 50%) without sufficiently integrating the GHG abatement of heat supply. The installation of heat pumps, which is essential for decarbonization of the heat used in buildings, proceeds very slowly. The current energy retrofit rate is found insufficient to achieve the objectives of the Swiss Energy Strategy 2050. It is therefore very important not only to increase the rate of energy retrofitting but also to ensure that the systems installed are more efficient in terms of GHG emissions.