IEA HPT Annex 50: Heat Pumps in Multi-Family Buildings for Space Heating and DHW

The project aims at demonstrating the potentials of heat pump technology for the energy supply of multi-family houses (MFH) and to contribute to the elimination of existing market barriers. Concepts and innovative technology options for heat pumps in MFH will be investigated in detail by means of simulations and experiments. The findings and results will be presented in international expert meetings and disseminated among national heat pump manufacturers, installers and planners.

Short Description

At European and national level, only one in ten heat pumps sold has a heating capacity >20 kW and would thus be suitable for (centralized) utilization in multi-family houses (MFH). While heat pumps are widely used in single-family homes, there is a huge potential for expansion in the MFH sector.

Due to the poor data situation and the lack of concepts for the integration of heat pumps in MFH, the objective of this IEA project was to examine the current market situation in detail and to investigate which heat pump technologies and system configurations are suitable for utilization in MFH and how an increased market penetration can be achieved through the correct use of these technologies. In addition to Austria, Germany, France, Italy, Denmark, Switzerland and the Netherlands participated in the project. The national project IEA HPT Annex 50 had been funded by the Federal Ministry for Climate Protection, Environment, Energy, Mobility, Innovation and Technology. The project was executed analogously to the international annex within a consortium of AIT Austrian Institute of Technology and TU Graz:

At first the data regarding the Austrian heat pump market for MFH was processed and the potential for the replacement of heating systems in MFH by heat pumps was estimated. Of the approximately 260,000 existing MFH, about 60,000 MFH already meet the requirements for an immediate exchange of the heating system with a heat pump. At a renovation rate of 3 %, about 8,000 MFH would be added to this number per year. In addition, an international collaboration created a system classification matrix and an online pre-selection tool based on it.

In further steps methods for the energetic evaluation of heat pump combinations with solar thermal and photovoltaic systems were elaborated and an Excel tool based on them was developed. In the field of acoustics, results from current research projects, e. g. SilentAirHP (FFG No. 848891) were incorporated into the annex. One highlight is a catalog of measures with details of the achievable noise reduction in dB(A) per measure. The best example is the optimization of the control system with up to 10 dB(A) sound reduction.

In the course of the simulation work optimal cooling circuit configurations for air source heat pumps in newly built, refurbished as well as unrefurbished MFH were identified: For all applications, refrigeration circuits with the refrigerant propane (R290) show the best efficiency. Especially for applications with higher temperatures, the refrigeration circuit variants with EVI (refrigerant injection in compressor)) achieved the highest values. In the course of the system simulations, the real solar/ice storage heat pump system "Hot Ice" was simulated and compared with the modeled air/water heat pump. By means of dynamic system simulation, the system could be analyzed in depth (e.g., effect of the size of the heat source system) to identify optimization potentials. The control system was optimized in the process of system evaluation. The sensitivity analysis shows that especially a larger heat source system (ice storage and/or solar collector) would be advantageous in terms of efficiency and energy consumption. The system was prepared as an Austrian case study for the international project website and the operating experience gained can be used in the planning and implementation of comparable systems in the future.

Project Partners

AIT Austrian Institute of Technology GmbH, Center for Energy
Project manager: Andreas Zottl
Project staff: T. Natiesta, M. Lauermann, Ch. Reichl, S. Zibuschka
Giefinggasse 2, 1210 Wien
Tel.: +43 (0) 50550-6309

Graz University of Technology, Institute of Thermal Engineering
Project manager: René Rieberer
Inffeldgasse 25/B, 8010 Graz
Tel.: +43 316 873 - 7302


Austria, Denmark, France, Germany (Operating Agent), Italy, Netherlands, Switzerland