Study finds heat pump efficiencies falling short
23rd March 2025
SWITZERLAND: A two-year survey of over 1,000 heat pump installations across Central Europe claims that 17% of air-source and 2% of ground-source heat pumps fail to meet European efficiency standards.
In addition, around 10% of systems were found to be oversized and approximately 1% undersized. There was also found to be a significant variability in performance among individual heat pumps, with a 2-3 fold difference between the lowest and highest efficiency systems.
The survey, carried out by a team from the science and technology research university ETH Zurich and the Institute of Technology Management at the University of St Gallen, is claimed to be the largest field study to date, being based on the analysis of sensor data from 1,023 heat pumps across Central Europe.
Researchers insist the results highlight the critical need for standardised post-installation performance evaluation procedures to ultimately improve operational efficiency and inform future installations. This would include the development of digital tools to deliver actionable feedback for users and installers.
The report observes that heat pumps exhibit greater complexity compared to well-established gas and oil heating systems and, unlike these traditional systems, they have not undergone decades of optimisation.
It also notes that heat pump performance is influenced significantly by factors beyond design, such as occupant characteristics and system settings, which is a challenge for manufacturers, installers and owners. Consequently, it argues that, in practice, the actual energy consumption of heat pumps can deviate significantly from expectations, resulting in substantial additional operating costs.
The analysed data encompasses a wide variety of heat pump models and configurations installed in residential buildings across 10 countries in Central Europe.
The study monitored the heat pumps for up to 777 days between 2021 and 2023. This included 890 air-to-water heat pumps and 133 brine-to-water heat pumps. There were no water-to-water HPs in the data set.
The heat pumps monitored were installed in residential buildings in Germany (434), the Netherlands (211), Austria (204), Czech Republic (78), Sweden (46), Denmark (35), Poland (3), Slovenia: (2), France (1), Great-Britain (1), and unknown (8).
In total, the data set contains 185,139 daily observations at outdoor temperatures of 15ºC or below, with each heat pump having an average of 182.22 days of data within this temperature range.
The report was published in Nature Communications.
