Changes to permitted development rights for air source heat pumps in England came into force on Thursday 29 May 2025, removing the requirement for a planning application in more cases. The Department for Energy Security and Net Zero set out the changes in a press release published on 6 June 20251, and the certification body MCS confirmed the same commencement date2.
The changes do four things. They remove the one metre boundary rule, so an air source heat pump can be installed within one metre of the property boundary; they raise the size limit for the outdoor unit on a dwellinghouse from 0.6m3 to 1.5m3; they double the number of heat pumps permitted on a detached dwellinghouse from one to two; and they allow air source heat pumps that can be used for cooling as well as heating, which the government says facilitates the roll out of air-to-air models1. MCS lists the same four changes2.
| Change | Before | From 29 May 2025 |
|---|---|---|
| Distance from boundary | At least 1m | No minimum |
| Unit size limit (dwellinghouse) | 0.6m3 | 1.5m3 |
| Units per detached house | 1 | 2 |
| Cooling | Not covered | Air-to-air models included |
Installations under the permitted development route in England must comply with a noise assessment methodology, including an upper noise limit assessed at the nearest neighbouring habitable room window or door, as part of the Microgeneration Certification Scheme Planning Standard1. MCS said the updated rights refer 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 Standard2. Compliance with MCS 020 a) under permitted development applies whether or not the installation is MCS certified2. Installations in Scotland, Wales and Northern Ireland must continue to comply with MCS 020 until further notice2.
"The simplification of planning rules will help millions of homeowners, particularly in normal family homes in towns and cities, take advantage of this technology."
The government cited figures from Octopus showing that 34% of those who order a heat pump are discouraged or drop out for reasons attributed to the need to submit a planning application1. Aira, an installer, said its own data showed 30 to 40% of homeowners needed planning permission to install a heat pump, often waiting up to six months for approval3. The government also said the first quarter of 2025 saw a record number of applications to the Boiler Upgrade Scheme, up 73% from the same quarter in 2024, with 11,256 applications between January and March 20251. The scheme provides households with up to £7,500 off the cost of a heat pump1.
Why it matters for households
For a household, the boundary rule was often the difference between a heat pump fitting on the available ground and needing a planning application. Removing it widens the number of homes where an air source heat pump can go in without that process, particularly terraced and semi-detached properties with little space at the side or rear. The larger size limit of 1.5m3 also matters because higher-output units are physically bigger; Aira states its 12kW model measures approximately 0.75m33, well inside the new limit but above the old one. Allowing two units on a detached house gives those homes the option of a larger combined capacity or a split installation.
The noise condition is unchanged in substance and remains the practical constraint. A unit still has to meet the assessed limit at a neighbour's habitable room window or door1, so siting decisions are not unlimited even though the boundary restriction has gone. The change applies in England only; the devolved nations continue under the previous standard2. For a home's energy independence, the effect is procedural rather than technical: it removes a permission step from the path to a heating system that runs on electricity rather than gas, which is the same direction of travel as the government's wider heat pump policy.
What happens next
The government said it is publishing the Future Homes Standard in autumn 2025, and that it will see homes built with low carbon heating such as heat pumps and heat networks1. The technical detail of that standard was still being set with industry at the time of the announcement1. No further changes to the permitted development rules for heat pumps in England have been reported.