SOUND FROM DOMESTIC AIR SOURCE HEAT PUMPS: A CASE STUDY

Air source heat pumps can be used to extract heat from the atmosphere to heat buildings more efficiently than 100% electric heating. The Committee on Climate Change has stated that ‘new homes should not be connected to the gas grid from 2025’ and the Future Homes consultation indicates that ‘there is a need to establish heat pumps as a mass market solution for low carbon heating’. Domestic heat pumps are installed in the UK under the Microgeneration Certification Scheme, which avoids the need for local authorities to scrutinise their installation and is necessary in order to expedite the reduction of the UK’s greenhouse gas emissions. As part of the scheme the installer must complete a noise assessment that requires the total sound pressure level, plus a notional background noise level, not to exceed 42dB LAeq,5mins at the nearest residential receiver. However, this assessment methodology fails to account for the strong acoustic features present in the sound produced by heat pumps. This paper presents a case study where complaints about sound from a heat pump installed under the Microgeneration Certification Scheme were investigated. Practical measures for reducing the sound from heat pumps are presented as well as potential improvements to the standardised assessment methodology used by installers.