Detailed efficiency analysis for heat pumps in existing singlefamily houses within a large-scale field test
The study presents the main results of the efficiency analysis from the field measurement “WP-QS im Bestand” in which 77 heat pumps in existing single-family houses (built between 1826 and 2015; for the efficiency analysis, buildings up to 2001 were considered) were examined in detail using appropriate measurement technology. For 49 air-source heat pumps, seasonal performance factors (SPF; generator efficiency, combined for space heating and domestic hot water) between 2.6 and 4.9 were determined, with an average of 3.4. The 13 ground-source heat pumps investigated achieved SPF values from 3.6 to 5.4, with an average of 4.3. The assignment of the measured objects to different building age periods showed no significant correlation between efficiency and building age. The determined annual efficiency factors in space heating mode range from 0.44 to 0.52 for nine ground-source and from 0.32 to 0.44 for 49 air-source heat pumps. The reduction in greenhouse gas emissions compared to a gas boiler as reference system - considering time-variable factors such GHG emissions of the electricity and the electrical loads of the heat pumps - amount to 58% in 2023 and 64% in 2024.