MCS introduced amended air source heat pump (ASHP) standards on 20 March 2025, with a further amendment on 23 April, according to the Welsh Government's summary of responses to its consultation on changes to permitted development rights1. The Welsh Government states that all air source heat pumps installed under permitted development rights will need to comply with MCS 020(a) standards, alongside other limitations covering unit volume, number, location, design and sensitive areas1.
The consultation, "Changes to Permitted Development Rights", was launched on 8 April 2025 and was open for responses until 1 July 2025, setting out 49 specific questions1. It generated 174 responses during the consultation period plus 2 late responses, a total of 1761. Respondents were asked to assign themselves to one of six categories1.
| Respondent category | Number | % of total |
|---|---|---|
| Business/Consultant | 36 | 20% |
| Government Agency/Other Public Sector | 11 | 6% |
| Local Planning Authority | 15 | 9% |
| Other Group or Individual (not listed above) | 83 | 47% |
| Professional Bodies/Interest Groups | 21 | 12% |
| Voluntary Sector/Community Groups | 10 | 6% |
| Grand Total | 176 | 100% |
Two of the ASHP proposals drew majority support. On removing condition G.3(a), which requires an ASHP to be used solely for heating purposes so that air-to-air heat pumps can also be installed, 78% of those answering agreed, with 5 against and 25 answering "don't know"1. On removing the limitation requiring an ASHP to be 3m from the property boundary, 76% agreed, with 9 against and 24 answering "don't know"1. The Welsh Government said the majority of responses showed strong support for removing condition G.3(a), and that it considers the potential benefits will enhance consumer choice and encourage the adoption of low-carbon technologies in households across Wales1.
"All air source heat pumps installed under permitted development rights will need to comply with MCS 020(a) standards"
The summary records that frequently raised benefits of enabling air-to-air heat pumps included cost-effectiveness and affordability, suitability for smaller or older homes, greater consumer choice, cooling during warmer months, health benefits and fewer regulatory barriers to low-carbon heating1. Concerns included the need for more data on environmental impacts, noise levels and potential increases in electricity demand from cooling, with calls for further technical guidance and noise controls1. On the 3m rule, respondents cited reduced noise levels from technological improvements, policy consistency across the UK, decarbonisation and social equity, and the importance of maintaining noise control measures; the most frequent concern was potential noise nuisance1. Some responses argued for continued controls in sensitive locations such as conservation areas or listed buildings1.
Why it matters for households
Permitted development rights allow certain home energy installations without a planning application. The standards an ASHP must meet therefore shape what a household can install, and where, without seeking consent. The Welsh Government states that where compliance is not achieved, a planning application will be required1. The 3m boundary rule was described in responses as disproportionately affecting households with limited outdoor space, where compliance can be difficult1. The consultation also covered off-street EV charging, temporary campsites, reverse vending machines, development by statutory electricity undertakers, affordable housing and meanwhile uses, and the definition of major development1. Planning rules differ across the UK nations; the Welsh Government's controls are set out separately from those of DESNZ, and Article 4 directions can withdraw permitted development in specific areas.
What happens next
The summary states that these changes will be taken forward when the necessary resources become available in a second phase of implementation1. It also refers to a further consultation which launched on 7 July1. No date has been reported for the second phase, and no commencement date for the amended standards under permitted development rights has been reported.