Experimental comparison of heat pump seasonal efficiency using EN 14825 and a dynamic load emulation approach
Heat pumps are central to the EU’s climate neutrality goals, particularly for decarbonizing the building sector. Current standards, such as EN 14511-3 and EN 14825, assess performance under steady-state conditions, which do not reflect real-world dynamic operation or interactions with the building. This study presents a test campaign on an air-to-water heat pump, comparing conventional standard procedures with a load-based test (compensation method) that maintains the unit’s native control strategy. Results show that the compensation method provides a more realistic representation of performance under varying loads, especially at low temperatures and below the unit’s minimum capacity. Conventional standard tests tend to overestimate heating capacity and COP because they do not include ON-OFF cycling at very low part-loads, the occurrence of defrost cycles at lower outdoor temperatures and the presence of oil recovery under certain conditions. When these factors are incorporated into a seasonal performance assessment, the overall efficiency of the tested unit decreases up to 15%, leading to a one-class downgrade of its energy label. The findings highlight the value of dynamic, load-based testing for modern modulating heat pumps.