The replacement of outdated and inefficient fossil fuel residential heating systems (RHS) by more efficient and less CO2-intensive appliances primarily based on renewable energy sources is an important pillar for the transition to a cleaner and more sustainable energy system. This paper empirically investigates drivers and barriers behind homeowners' decisions to switch from a fossil fuel to a renewable RHS in Germany. For this purpose, we draw on data from a 2010 questionnaire survey among owners of existing single-family and duplex houses in Germany that had received a financial grant to install an RHS (i.e. condensing boiler with solar thermal support, heat pump or wood pellet boiler). We show that environmental protection, a lower dependency on fossil fuels, and a higher degree of RHS-related knowledge are key drivers. In contrast, the perceived difficulty of getting used to the system and a misunderstanding of its principal functioning are obstacles for the heat pump. For the wood pellet boiler, perceived barriers include the low usability, the labor-intensive operation, and the systems' fault liability. Hence, a higher replacement rate requires the willingness to relinquish old habits and perceptions of how an RHS works and operates. (C) 2015 Elsevier Ltd. All rights reserved.