Using heating systems to cool rooms

Cooling with heating systems
© Shutterstock/Stanisic Vladimir
Studies by Fraunhofer IBP have shown that cooling rooms with radiators as well as with underfloor heating systems has the potential to markedly reduce indoor air temperatures in summer.


The energy required to cool rooms has been rising for years and, according to forecasts by the International Energy Agency (IEA), will triple worldwide by 2050. In Germany, experts expect energy consumption for cooling residential buildings to double over the next 20 years. Against this backdrop, a significant increase in the installation of new cooling systems is anticipated. A cost-effective alternative is to use the existing heating system. This can be employed to cool interiors by using the system’s heat pump in reverse operation.


Studies by Fraunhofer IBP have shown that cooling rooms with radiators as well as with underfloor heating systems has the potential to significantly reduce indoor air temperatures in summer - without causing unwanted condensation on cold surfaces.


When dimensioning the system, particular attention must be paid to the following aspects:

  • The potential cooling capacity of the respective system with its specific constraints (e.g. room geometry/use, percentage of window surface area)
  • The effects of temperature changes on floor coverings and other materials and systems in the room
  • Compliance with comfort conditions (e.g. floor surfaces that are too cold are perceived as unpleasant)
  • Prevention of mold growth in the room by regulating the temperature according to the dew point 


Through our unique combination of laboratories, simulation options and hygrothermics expertise, we can study and optimize systems as well as develop control algorithms.

  • In-depth measurements in the test room: this precisely defined, monitored environment enables us to investigate different heating or cooling systems under controlled indoor and outdoor climatic conditions. The innovative measuring equipment delivers a wide variety of results that allow conclusions to be drawn about the potential and possibilities of the studied systems.
  • Computational simulation with WUFI® Plus: calculations with our software tool WUFI® Plus allow us to comprehensively evaluate heating and cooling systems for different types of building.
  • Years of expertise and interdisciplinary cooperation between Fraunhofer IBP experts

You can find more information in our flyer (only German).


  • Pleasant cooling in summer without the need to install a new system 
  • Particularly interesting concept for older buildings because existing hardware is relatively easy to adapt
  • Energy-efficient cooling through the use of heat pumps and the building’s heat storage effects 
  • Greater clarity about the market potential of different systems, maintains a technological lead
  • More planning security for the system provider, clear information on application requirements and limits
  • Avoidance of moisture damage (e.g. mold growth) or damage to floor coverings