Air source heat pumps - guidance update

Prepared jointly by the Institute of Acoustics (IOA) and the Chartered Institute of Environmental Health (CIEH), this new guidance supports quicker, lower-cost installation of air source heat pumps, while continuing to protect neighbours from noise in line with the current Air Source Heat Pump Sound Calculation Standard (MCS 020a). It offers clear, proportionate advice on acoustic assessment methods for planning applications where permitted development rights do not apply, helping to reduce unnecessary bureaucracy. The guidance aims to streamline the process and remove barriers that may delay or discourage ASHP installations, which are vital to meeting the UK’s 2050 net zero target. It also sets out good acoustic design principles, including careful siting, vibration control, and avoiding unnecessary enclosures. The approach is based on evidence and the current knowledge of the working groups involved, and the guidance is expected to be updated as experience develops.

The note advises that planning conditions related to noise will rarely be required and, where justified, should be simple, precise and proportionate.

The guidance introduces defined assessment pathways that sit between the existing MCS 020a method and full BS 4142 (noise rating assessment), which is often a requirement of local authorities. The guidance includes example conditions to assist local authorities with a different approach. For most installations, simple compliance routes are set out, including desktop calculations demonstrating compliance with a 37 dB(A) sound level criterion. More detailed assessments are reserved for exceptional or sensitive situations, such as tranquil locations or developments with multiple units and potential cumulative impact.

Currently the 37 dB(A) threshold is considered to account for tonal characteristics, aligns with established European and Scottish practice, and has not led to increased noise complaints. The guidance also clarifies appropriate selection of manufacturer sound power data and where the grey areas in knowledge exist.

This new advice replaces earlier guidance and has been developed by a joint working group of acousticians and environmental health professionals, with input from the Association of Noise Consultants. It is intended to provide consistent, evidence-based decision-making for local planning authorities, environmental health practitioners, and installers, supporting the rapid and responsible rollout of low-carbon heating across the UK.

Full Guidance: 
Joint IOA CIEH Domestic ASHP Professional Advice Note (2026)