On Thursday 29 May 2025, the UK government implemented changes to Permitted Development Rights (PDR) for air source heat pumps in England.
The key changes:
- Enable heat pumps to be installed within 1m of the property boundary.
- Increase the size limit of the heat pump from 0.6m3 to 1.5m3 for dwelling houses.
- Double the number of heat pumps permitted, from one to two, for detached. dwellinghouses
- Allow air source heat pumps to also be used for cooling, meaning air-to-air heat pumps can now also benefit from the permitted development rights.
How to stay compliant
The updated PDR in England refers to the MCS 020 a) Standard, which air source heat pump installations in England must comply with from 29 May (replacing the previous MCS 020 Standard).
Please note that regulations vary across devolved nations. Check below to make sure you’re complying with the correct standard:
England – air source heat pump installations must comply with MCS 020 a) from 29 May 2025
Scotland, Wales & Northern Ireland – installations must continue to comply with MCS 020 until further notice
What is the difference between MCS 020 and MCS 020 a)?
MCS 020 is a Standard that helps make sure air source heat pumps and small wind turbines can be installed in homes without needing planning permission. As outlined above, installations must continue to comply with MCS 020 in Scotland, Wales and Northern Ireland.
The updated version of the Standard, which is applicable to installations in England, is now split into two: MCS 020 a) for air source heat pumps, and MCS 020 b) for wind turbines.
This is to simplify compliance for installers and includes an updated calculation methodology for air source heat pumps.
The key changes in MCS 020 a) include:
- MCS clarification of:
- What can and cannot be considered a solid barrier.
- How to determine the assessment position.
- What can and cannot be considered a reflective surface.
- The definition of a habitable room.
- Introducing a methodology for including up to two air source heat pumps in the MCS 020 a) sound calculation.
- Options for completing the sound calculation which include the current paper-based method and an Excel tool.
- A sound calculation for up to four air source heat pumps is now included in the Excel tool to benefit those installing under full planning permission
- MCS will develop functionality to hold the A-weighted sound power level for MCS certified products on the MCS Product Directory to support installers in using this figure in the MCS 020 a) calculation.
- Compliance with MCS 020 a) under PDR will apply irrespective of whether it’s an MCS certified installation or not.
More advice and information
To access the Standards, please visit the MCS Standards & Tools Library
If you’ve got any questions, or need any further support, please contact the MCS Helpdesk on 0333 103 8130 or email hello@mcscertified.com.