Efficiency of heat pump systems under real operating conditions

The importance of accurate data for real-life performance of heat pumps is well known. Although we talk of a mature technology, there is still discussion concerning the efficiency or the burden of heat pumps. This, and other reasons, has led the Fraunhofer Institute for Solar Energy Systems ISE (Freiburg, Germany) to carry out large-scale monitoring projects for over ten years. With particular emphasis on heat pumps in single-family homes, about 200 heat pumps have already been monitored. The detailed measurements enable us not only to evaluate the efficiency, but also to analyse the operational behaviour, and so provide answers to important questions.