Heat pumps are a proven solution for the decarbonization of the heat supply, both for space heating and domestic hot water, in individual houses. However, the implementation of heat pump systems in multi-family buildings remains marginal. The main challenges include the lowering system temperatures on the supply side (space heating and domestic hot water) and difficulties in accessing suitable heat sources in densely populated urban areas. This study presents a comparative and multi-criteria analysis of the potentials and constraints of various heat pump solutions using the natural, low Global Warming Potential refrigerant propane (R-290). It evaluates the technical feasibility and user-related aspects such as acoustics and appearance of different heat pump systems implemented in various types of existing multi-family buildings based on real case studies in Germany. After characterizing available heat sources and building demands, the energy performance of the heat pumps systems is examined through simulation. Further aspects such as the investment costs, space requirement and safety requirements due to R-290 flammability are evaluated bases on literature data and expert opinion. The findings highlight the potential of propane-based heat pumps to provide a sustainable and efficient alternative to conventional heating systems but also the complexity of finding solutions under the boundaries of existing buildings. The multi-criteria approach ensures a comprehensive assessment, offering valuable insights for policymakers, engineers, and stakeholders aiming to enhance the sustainability of heat supply in existing multi-family buildings.