The heat transition in the German building sector is one of the major transformative challenges on the way to a climate-neutral society by 2045. In addition to reducing the per-capita living space and decarbonising the heat supply, the focus is on reducing the final energy demand by increasing energy efficiency. The aim of this short study is to identify new financing instruments for the heat transition in the building sector that have so far had little or no visibility in the political discourse. The focus is on instruments that aim to mobilise private capital to increase energy efficiency in residential buildings while at the same time contributing to a socially just implementation of the heat transition. The study presents these instruments and their respective modes of action in a compact but informative form and illustrates their design and possible effects using selected examples from German, European or international practice. The scalability and/or transferability of the analysed instruments in the German context are also provisionally assessed with regard to identified success factors and challenges.