The German government has set ambitious climate-protection targets to limit global warming. The aim is to achieve an energy-efficient and almost climate-neutral building stock by 2050. This applies particularly to buildings, responsible for more than 20% of CO2 emissions. The aim is to reduce the primary energy demand of buildings by 80% by the end of 2050. Achieving a nearly climate-neutral building stock requires targeted modernization measures that contribute to increasing energy efficiency. Barriers confronting the implementation of energy-efficient measures include lack of knowledge due to inadequate provision of information, lack of trust, and problems regarding financing possibilities. Therefore, solutions are needed for holistic concepts that make energy-efficient building and modernization more attractive. In addition to traditional business models (BM), measures that accelerate the implementation of energy-efficiency and BM that support the sustainable development of potential customers are sought. Expert knowledge must be shared to close information gaps; savings guarantees must be considered to build trust, and finally, financing possibilities must be available to support implementing sustainable measures. ... mehrThe research focuses on a modification of BM under the aspect of increasing energy efficiency in buildings for customers. This approach considers specific functions, effects, and benefits of BM. The aim of this extension is to create a basis for systematizing existing BM on the one hand, and on the other, to extend the proposed methodology. Finally, the developed guide supports startups designing new BM.