MCS published its response to the consultation on updates to the MCS 020 standard on 22 November 20241. The standard governs sound levels for air source heat pumps and small wind turbines1. MCS consulted on the planning requirements for air source heat pumps in domestic properties, including the MCS 020 calculation, in November 2023; the consultation closed on the 26th January 2024 with 55 responses from a wide range of organisations1. MCS states the changes are linked to the recent DESNZ announcement on planning requirements for air source heat pumps1.
The confirmed changes are:
| Change | Detail |
|---|---|
| Split of the standard | 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 |
| Sound limit | The sound calculation will be simplified to create an overall limit of 37 dB(A)1 |
| Product data | The A-weighted sound power level for MCS certified products will be held on the MCS Product Directory1 |
| Rural and urban | MCS will not proceed with differentiating between rural and urban areas and will not implement the postcode look up tool1 |
| Multiple units | A methodology will be introduced for including up to two air source heat pumps in the MCS 020 (a) sound calculation1 |
| Guidance | A guidance document for installers on installation sound mitigation measures for air source heat pumps will be developed with DESNZ and other industry stakeholders1 |
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. Compliance with MCS 020 under Permitted Development Rights will apply irrespective of whether it is an MCS certified installation or not1.
"MCS will simplify the sound calculation to create an overall limit of 37 dB(A)."
The MCS 020 noise assessment sits within the wider MCS certification scheme, which sets product and installation standards for small-scale renewables. The sound power level data now to be held on the MCS Product Directory sits alongside other product standards and markings information used to compare certified equipment.
Why it matters for households
The MCS 020 calculation is the tool used to show that an air source heat pump meets the noise limits that apply under Permitted Development Rights in England1. A single overall limit of 37 dB(A), replacing a proposed rural and urban split, gives one figure to work to rather than a location-dependent one1. Publishing A-weighted sound power levels on the MCS Product Directory means the noise figure for a certified unit is stated in a public listing rather than being established only at the assessment stage1. The clarification of solid barriers, reflective surfaces, assessment positions and the definition of a habitable room addresses the inputs that determine the result of the calculation1. The methodology for up to two air source heat pumps means a property with two units can be assessed within the same standard1. Because compliance applies whether or not the installation is MCS certified, the calculation is relevant to any air source heat pump installed under Permitted Development Rights1.
What happens next
MCS expects to publish MCS 020 (a) in December1. The guidance document for installers on installation sound mitigation measures is to be developed with DESNZ and other industry stakeholders; no publication date for it has been reported1.