Energy Potential of Existing Reversible Air-to-Air Heat Pumps for Residential Heating

Heat pumps can be considered one of the key technologies to meet the building stock decarbonization target set by Europe. Especially in warm locations, many households have already incurred costs for the installation of air-to-air heat pumps, but, in most cases, they only use them in summer for cooling, while heating is provided by fuel-fired boilers. For these households, the goal of reducing primary energy consumption could be achieved almost cost-free by using heat pumps, that were installed for summer cooling, also for winter heating. Based on this assumption, this research aimed to evaluate the energy savings and environmental benefits that can be achieved by using air-to-air heat pumps instead of gas boilers as the main heating system, without additional costs except for the installation of electric radiators in bathrooms. To quantify variations in energy, environmental, and economic savings compared to the baseline condition, detailed simulations were conducted with the dynamic hourly calculation method (EN ISO 52016) in six different European locations, considering heat pumps with different efficiencies and two different building types. The analysis showed positive impacts at all sites due to the use of heat pumps, which can lead to primary energy savings ranging from about 20% to about 60%. The results varied according to outdoor climate, coefficient of performance of heat pumps, building type, and, on the economic side, the cost of energy. This research provides useful results for outlining decarbonization scenarios, assuming that heat pumps are one of the technologies needed to meet the EU's climate neutrality goal.