To the 15th IEA Heat Pump Conference, a contribution from IEA HPT Annex 63 Task 3 has been submitted, which will present a listening experiment that was conducted across seven European countries and ten sites to evaluate the cumulative impact of multiple Air Source Heat Pumps (ASHPs) in residential back gardens. The study investigates noise annoyance responses to a sample of sounds of ASHPs under varying operating conditions, considering three different noise barrier types and two background noise sound pressure levels. The experiment comprised three parts: (1) assessment of a single ASHP in various operating states, combined with two background noise levels and all three noise barrier types; (2) analysis of paired ASHPs with varying distances, operating state combinations, and inter-unit noise barrier types; and (3) evaluation of configurations with three to six ASHP units, simulating realistic residential layouts. In each part, participants provided annoyance ratings using a standardised scale. The study aims to identify how factors such as the number of operating units, their spatial arrangement, operating conditions, and the presence of noise barriers influence noise annoyance. The results provide valuable insights for the acoustic planning and design of heat pump installations in high-density urban areas.
