A better understanding of energy efficiency in the Swiss building stock, currently insufficient at the local level, is fundamental to achieve the goals of the Swiss energy strategy 2050. This study focuses on energy retrofitting of multi-family residential buildings in Geneva, integrating technical, economical, financial and environmental aspects, as well as preservation of cultural heritage.The first part provides a detailed overview of the current physical, structural and energy-using characteristics of existing building stock and analyzes the renovation market dynamics as well as the actors involved and their practices. The assessment of the energy performance of several retrofit operations revealed in the second part that the real space heating demand of the retrofitted buildings were consistently higher than those provided by calculation. It also shows that the higher the predicted space heating saving potential is, the higher share of this potential will be reached in reality. The last part evaluates the theoretical energy saving potential for space heating in the multi-family building stock and provides concrete recommendations to mobilize efficiently this potential.In conclusion, the achievement of the ambitious goals set by the Swiss federal government, particularly those which aim to reduce by half the space heating demand by 2050, is hardly possible without an improvement of the current practices regarding the actors involved in building retrofit process (process that starts with the energy audit and ends with the use of the buildings by the occupants and energy managers).