Energy performance assessment of heat pump systems in three existing multi-family buildings in Europe based on field measurement

Heat pumps, powered by low-emissions electricity, are a proven solution for the decarbonization of the heat supply, both for space heating and domestic hot water, in buildings. However, the implementation of heat pump systems in existing multi-family buildings remains marginal. One of the main technology challenges is the high temperature requirements in this type of building, which significantly affect the heat pump performance and the necessity to install a backup heater. The EU-funded research project HAPPENING aims to address this challenge by developing an easy-to-plan and easy-to-install solution based on decentralized heat pumps. The HAPPENING solution can be customized to accommodate the different constraints and requirements in existing multi-family buildings. One common feature of HAPPENING systems is that they are all driven by a low-grade renewable heat source. The heat source can be different, such as a geothermal field, an air source heat pump or a low-temperature district heating network. The existing hot water distribution pipes is utilized as low temperature distribution loop, and each dwelling is equipped with a decentralized heat pump to provide the required heating supply temperature. The electricity use of the heat pumps can be supported by PV panels, which can be installed in the roof or façade of the buildings. This study evaluates the energy performance of the HAPPENING systems in three existing multi-family buildings based on field measurement data. The demonstration buildings are located in Spain, Italy and Austria, each operating under different climatic conditions and with different control strategies. The study compares them to standard solutions in existing multi-family buildings in terms of primary energy use and green house gas emissions. The temperature levels and energy flows provided by the heat pumps are examined and evaluated as part of this study. The findings demonstrate the technical feasibility of retrofitting HAPPENING systems to existing multi-family buildings and provides insights on addressing challenges related to high temperature requirements.