MCS has published its response to the recent consultation on updates to the MCS 020 standard, which governs sound levels for air source heat pumps and small wind turbines1. The consultation closed on the 26th January 2024, having received 55 responses from a wide range of organisations1. MCS consulted in November 2023 on the planning requirements for Air Source Heat Pumps in domestic properties including the MCS 020 calculation, a process driven by the government's proposal to consult on changes to Permitted Development Rights that apply in England1.
The changes MCS has set out are intended to simplify compliance and enhance clarity for installers1. MCS will split the MCS 020 standard into two: MCS 020 (a) for air source heat pumps and MCS 020 (b) for small wind turbines, with no changes to the requirements for small wind turbines1. It will hold the A-weighted sound power level for MCS certified products on the MCS Product Directory1. MCS will also clarify what can and cannot be considered a solid barrier, how to determine the assessment position, what can and cannot be considered a reflective surface, and the definition of a habitable room1.
On the sound calculation itself, MCS will not proceed with the proposal of differentiating between rural and urban areas and therefore not implement the use of the postcode look up tool; instead it will simplify the sound calculation to create an overall limit of 37 dB(A)1. MCS will introduce a methodology for including up to two air source heat pumps in the MCS 020 (a) sound calculation1. Compliance with MCS 020 under PDR will apply irrespective of whether it is an MCS certified installation or not1. Working with DESNZ and other industry stakeholders, MCS will develop a guidance document for installers on installation sound mitigation measures for air source heat pumps1.
"MCS will simplify the sound calculation to create an overall limit of 37 dB(A)."
| Change | Detail |
|---|---|
| Standard split | MCS 020 (a) for air source heat pumps; MCS 020 (b) for small wind turbines |
| Sound limit | Overall limit of 37 dB(A) |
| Rural and urban | Differentiation not proceeding; postcode look up tool not implemented |
| Multiple units | Methodology for up to two air source heat pumps in the MCS 020 (a) calculation |
| PDR compliance | Applies whether or not the installation is MCS certified |
Why it matters for households
The MCS 020 calculation is the sound assessment that sits behind the planning requirements for an air source heat pump in a domestic property, so its terms shape what can be installed under Permitted Development Rights in England and how close a unit can sit to a neighbour's property. The move to a single overall limit of 37 dB(A), rather than separate rural and urban figures, removes the postcode-based distinction that had been proposed. The clarifications on solid barriers, assessment positions, reflective surfaces and the definition of a habitable room bear directly on how a proposed siting is judged, and the new methodology for up to two units addresses households considering more than one heat pump. Because compliance under PDR applies irrespective of whether the installation is MCS certified, the calculation is relevant to any household using those rights, not only to those using an MCS certified installer. Further detail on how sound and certification requirements are assessed is set out in Heat Pump Standards, Testing and Certification, and the wider planning context sits under regulation and policy.
What happens next
MCS expects to publish MCS 020 (a) in December1. The consultation response document is available from MCS1. No date has been reported for the installer guidance document on sound mitigation measures, which MCS says it will develop with DESNZ and other industry stakeholders1.