Heat Pumps in Existing Single-Family Homes

Wärmepumpen in Bestands-Einfamilienhäusern
© Fraunhofer ISE

Around 40 percent of all CO2 emissions in Germany are attributed to the provision of hot water and space heating for buildings. This is mainly due to the fact that inefficient gas and oil heating systems, which are harmful to the climate, are still being used in many existing buildings. In order to achieve the ambitious climate protection goals, it is necessary to equip existing buildings with heat pump systems. Good efficiency values are possible in older buildings! For building modernization, it makes sense to take a holistic approach in the planning, to reduce the building’s total energy demand, to interlink the different retrofit measures, and to optimally design the heat pump based on the specific building requirements. However, our analyses have shown that heat pumps can operate ecologically and economically even in buildings that have undergone little renovation.


  • more efficient operation possible
  • full building refurbishment unnecessary
  • long-term value enhancement for buildings
  • state funding
  • reduction of CO2 emissions compared to gas heating
  • use of own electricity from PV system

R&D on Heat Pumps in Existing Single-Family Homes:

  • optimization heat pump parameterization for building modernization
  • simplify heat pump installation
  • usage of natural refrigerants (focus on propane)
  • development safety concepts for flammable refrigerants
  • optimization of planning and efficiency during operation using artificial intelligence
  • analysis of load shifting potential of heat pumps in the field
  • optimization of extraction systems for environmental heat (outside air, geothermal energy, ground water, waste water, solar thermal energy) 

On This Topic from our Research Blog "Innovation4E":


The Heat Pump Ramp-up in Germany: What is Important Now

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Heat Pumps: Economic Consideration of Operating Costs, a New Perspective

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How do we get more heat pumps in existing buildings?

Final episode of a series on heat pumps in existing buildings: We should have courage to bet on the right technology “The signs are unmistakable. […] the cost of inaction is — keeps mounting. […] We have to move quickly to meet these challenges.” said U.S. President Joe Biden at the start of his online […]
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Can heat pumps only be used in one- and two-family houses?

Episode 11 of a series on heat pumps in existing buildings focuses on heat pumps in multi-family houses. Heat pumps are required in multi-family houses Heat pumps have a very wide range of applications. The building sector is the most prominent example, but they are also deployed in industry, white goods, and electromobility. When they […]
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Marek Miara

Heat Pumps in Existing Buildings”, a Blog Post Series in 12 Parts

In the blog post series "Heat Pumps in Existing Buildings", our author Marek Miara answers the most pressing questions about heat pumps in existing buildings.

Our R&D Services on this Topic:

System Analysis and Optimization

Quality Assurance

Research Project

"WPsmart im Bestand"

Heat Pump Field Trial – Focus Existing Buildings and Smart Control