The heating transition will only pick up speed with heat pumps

Heat pumps play a decisive role in the building sector in achieving the goal of climate neutrality by 2045. This is because around 80 per cent of the 25 million installed heat producers are still heated with fossil fuels such as gas, oil or coal. The latest amendment to the German Buildings Energy Act has set the framework for decarbonising the heat supply in buildings. Since 1 January 2024, all new heating systems installed in newly built homes must use at least 65 per cent renewable energy; for existing buildings, the law will come into effect later. The focus is increasingly on apartment buildings, in addition to smaller residential buildings. They play an important role because every second residential unit is located in such a building.

Heat pumps have mainly been used in newly built buildings: Their use is around 36 per cent in apartment buildings. However, of the approximately 3.3 million existing apartment buildings, only around 3.3 per cent are currently heated with heat pumps. One in three heating systems is already over 20 years old. You can find further key figures on the building stock and heat generators in the dena Building Report.

Supplying heat to apartment buildings poses specific challenges.

These include:

• Limited space available for utilising heat sources in densely built-up areas
• High costs for the conversion of decentralised heating supply to a centralised supply
• Implementation of hygiene requirements for domestic water heating

A new guideline for heat pumps in apartment buildings, which dena has produced in collaboration with Bundesverband Wärmepumpe (BWP) e.V., GdW Bundesverband deutscher Wohnungs- und Immobilienunternehmen e.V. and the Fraunhofer Institute for Solar Energy Systems ISE, offers solutions to these requirements. The guide presents the status quo, recommendations for action and practical examples for the use of heat pump systems in apartment buildings.

Housing companies and homeowners have implemented pilot projects and research projects with heat pumps in existing apartment buildings and gained valuable insights for design, planning and operation in recent years. Many conceptual designs aimed at climate neutrality are also being developed and implemented. For example, dena supports the market development for serial refurbishment based on the Energiesprong principle to the net-zero standard, which includes the installation of heat pumps as an elementary component.

These projects show that heat supply via heat pump systems is feasible in large existing buildings. The majority of buildings are already suitable for heat pump systems, or low-investment measures in the building would allow for the efficient use of heat pumps. Lowering the temperatures in the heating system by replacing individual radiators, for example, plays an important role here.
There are tried and tested, diverse solutions that utilise various heat sources from the air, ground and water. In addition, there are various ways of distributing the heat in homes: centrally or in a decentralised manner via water in panel heating systems and radiators or directly via the room air. Heat pumps can also be successfully combined with solar panels and other components such as storage solutions or heating networks. The range of supply options is therefore very large and complex and it is a challenge to find the right system for a building. You can find a collection of successful projects with heat pumps at ‘Best practice portal for climate-neutral construction and refurbishment’ (in German) from Gebäudeforum klimaneutral.

The housing industry, researchers, heat pump manufacturers and experienced planners, installers and service providers already have a great deal of knowledge about the integration of heat pump technology in apartment buildings. What still needs to be driven forward is the comprehensive networking of stakeholders, the sharing and dissemination of knowledge and further development of solutions in order to develop the technology into a central component of the future heat supply in apartment buildings.

The efficiency and quality of heat pump systems are coming more into focus and are important factors for acceptance, low power consumption and therefore resource and environmentally friendly use of the technology. Here it is important to develop standards and solutions that guarantee quality, especially in the interaction between the stakeholders.

dena is working towards this goal with new projects and Gebäudeforum klimaneutral, which is shaping the transformation to a climate-neutral building stock together with network partners and local implementers. Expertise is provided in the form of high-quality information formats, including knowledge about heat pumps and increasing the number examples with a role model function.