Reductions in greenhouse gas emissions from space heating are considered as key to achieving climate policy goals. National measures to increase energy efficiency and support diffusion of renewable energy technologies appear necessary, because heating is not covered by the EU Emissions Trading Scheme. Exploiting a new and unique data set, we investigate (regional) drivers of investment in renewable space heating technologies as well as interaction of existing support schemes and building regulations in Germany. These analyses can provide a valuable contribution to understanding drivers of diffusion of new renewable energy technologies.