Across Europe and much of the industrialized world, cities are grappling with one of the largest energy transitions of our time: how to decarbonize the heating of homes and buildings. Heating represents a significant share of global energy use and greenhouse gas emissions, particularly in urban areas where multi-family residential buildings dominate the landscape.
In many countries, these apartment buildings are still heated largely by fossil fuels, including natural gas, oil, and coal-based district heating. This dependence contributes heavily to carbon dioxide emissions and leaves households vulnerable to fluctuating fuel prices and geopolitical uncertainties.
At the same time, new technologies and approaches are demonstrating how this reliance can be broken. Heat pumps, often combined with renewable electricity and smart control systems, have emerged as one of the most promising solutions. By moving heat instead of generating it through combustion, they deliver heating and cooling with far greater efficiency and without direct emissions.
It is within this global context that the International Energy Agency’s Technology Collaboration Programme on Heat Pumping Technologies (IEA HPT TCP) has launched Project 62: Heat Pumps for Multi-Family Residential Buildings in Cities. This international collaboration seeks to gather, analyze, and disseminate experiences from multiple countries on the use of heat pumps in apartment buildings.
Sweden, via RISE Research Institutes of Sweden, is one of the active participants. While Sweden is often highlighted as a leader in district heating, it also has a long history of using heat pumps in both single-family and multi-family buildings. By contributing its knowledge and case studies, Sweden offers lessons not only for countries where fossil fuels still dominate, but also for how heat pumps can be integrated into highly electrified, district-heated cities.
Sweden’s Heating Landscape: District Heating and Heat Pumps
Sweden is somewhat unique in Europe. For decades, it has relied on district heating systems to provide warmth to its urban population. In many cities, more than 90 percent of multi-family buildings are connected to district heating networks, which are increasingly supplied by biofuels, waste heat, and other renewable sources [1]. Gothenburg, for example, reports that about 90 percent of its apartment buildings are connected to district heating [2].
However, district heating is not the only solution. Heat pumps have become an integral part of Sweden’s heating landscape, especially for buildings seeking self-sufficiency, cost savings, or additional efficiency measures. According to international reporting, Sweden has installed over one million heat pumps across the country, spanning both residential and commercial applications [3][4].
In multi-family buildings, heat pumps are often used in three main ways:
1. As the main heating source, replacing fossil-based boilers entirely.
2. As a complement to district heating, reducing peak loads or recovering heat from ventilation and wastewater.
3. As targeted boosters, increasing efficiency in subsystems such as domestic hot water circulation.
The case study of the Village STHLM housing association in Stockholm’s Hammarby Sjöstad exemplifies how these strategies can be combined in practice.
Picture and text by RISE Research Institutes of Sweden
References
[1] Broström, T., et al. (2022). Heating in Sweden: District Heating in Multifamily Buildings. MDPI – Buildings, Vol. 12, Issue 7, p. 1007.
[2] Smart City Sweden (2023). Gothenburg Takes District Heating to a New Level of Sustainability. Available at: https://smartcitysweden.com/best-practice/309/gothenburg-takes-district-heating-to-a-new-level-of-sustainability.
[3] The Guardian (2023). Heat pumps are hot property in Europe – does Britain have cold feet? Available at: https://www.theguardian.com/environment/2023/dec/23/heat-pumps-are-hot-property-in-europe-does-britain-have-cold-feet.
[4] Rapid Transition Alliance (2023). Heat Pumps in Cold Weather: Snow Problem. Available at: https://rapidtransition.org/stories/heat-pumps-in-cold-weather-snow-problem.