In Europe, there is a clear long-term objective to decarbonize the energy system, but it is very unclear how this will be achieved in the heating and cooling sector. As a result, there is currently a lot of uncertainty among policymakers and investors in the heating and cooling sector, primarily due to a lack of knowledge about the long-term changes that will occur in the coming decades. This HRE proposal will enable new policies as well as prepare the ground for new investments by creating more certainty in relation to the changes that are required. The work in this proposal will build on three previous HRE studies, all of which have been successfully completed on time and all of which have already influenced high-level policymakers at EU and national level in Europe. The work from these previous studies will be significantly improved in this project. The new knowledge in this project will:- Improve at least 15 new policies at local, national, or EU level, - Specify how up to 3,000,000 GWh/year of fossil fuels can be saved in Europe, and- Quantify how the €3 trillion of investment required to implement these savings will reduce the net cost of heating and cooling in Europe.Furthermore, one of the most significant improvements compared to previous studies is the dissemination and communication strategy that has been developed as part of this proposal. These activities represent the largest work package in this proposal, which is necessary to ensure that policymakers, investors, and researchers at local, national, and EU level are all aware of the new data, tools, methodologies, and results from this project. The dissemination activities are expected to directly build the skills and capacity of at least 350 people in specific target groups identified by the consortium, while the communication activities will inform at least 50,000 people about the project activities and results.