Alternatives for upgrading from high-temperature to low-temperature heating systems in existing buildings: Challenges and opportunities

The decarbonisation of heating and cooling in buildings is key to achieving the European Union (EU)’s climate and energy targets. Energy consumed in buildings represents a significant proportion of the total energy consumed in the EU; improving their energy performance is therefore fundamental to achieving these targets. This paper outlines a methodology for supporting the energy transition in the sector, emphasising the substantial decarbonisation opportunities that existing buildings present, as well as the potential bottlenecks they may encounter. The impact of changing from fossil-based boilers to heat pumps is compared in typical building typologies in different climatic conditions across the EU, providing insights into the implications of switching from high to low-temperature heating systems regarding both costs and CO 2 emissions. The results show that a significant reduction in CO 2 emissions can be achieved by switching from gas and oil boilers to air/water heat pumps in the analysed countries. The paper also looks at the required enhancements of the hydronic facilities, and building envelope thermal insulation. Effective and well-targeted policies are needed to support the uptake and installation of clean heating systems, supporting homeowners in purchasing the right ones for their homes while supporting our climate goals.