From 28 May 2026, MCS 020a will be the only permitted certification scheme for air source heat pump installations that rely on permitted development rights in England, according to the Planning Portal1. The same date and the same effect are set out in planning guidance published by the London Borough of Richmond upon Thames on 22 April 20262.
Permitted development rights for domestic air source heat pumps have applied since 1 December 2011, meaning an installation does not need a planning application provided all the limits and conditions are met1. One of those limits is that the installation complies with the Microgeneration Certification Scheme Planning Standards (MCS 020a)1. The Planning Portal states:
"From 28 May 2026, MCS 020a will be the only permitted certification scheme."
Richmond's guidance refers to the standard as MCS 020 rather than MCS 020a, and says that until that date a heat pump may comply with MCS 020 "or an equivalent standard"2. The two pages therefore differ on the name of the standard and on whether an equivalent standard is currently accepted. Both give 28 May 2026 as the date from which only the MCS scheme will be permitted1.
The underlying rules sit in Part 14 (Renewable Energy) of the Town and Country Planning (General Permitted Development) (England) Order 20152. The main limits and conditions are:
| Condition | Requirement |
|---|---|
| Outdoor compressor unit volume | No more than 1.5 cubic metres on a house; 0.6 cubic metres for a block of flats1 |
| Number of units | Detached houses: first two units. Non-detached houses and blocks of flats: first unit only1 |
| Wind turbines | No existing wind turbine on the building or in its curtilage1 |
| Roofs | Not permitted on pitched roofs; on a flat roof all parts must be at least one metre from the roof edge1 |
| Listed buildings and scheduled monuments | Rights do not apply within the curtilage1 |
| Conservation areas and World Heritage Sites | No wall or roof fronting a highway, and no unit nearer to a highway than any part of the building1 |
| Use | Not solely for cooling; removed as soon as reasonably practicable when no longer needed1 |
Richmond's guidance adds that air-to-air units are now included within air source heat pump permitted development rights provided they are used for heating and not just cooling, and that ground source heat pumps do not usually require planning permission where the permitted development criteria are met2. It also states that none of the Article 4 Directions in the borough have removed permitted development rights for heat pumps2. The Planning Portal notes that permitted development rights may be removed through a planning condition, an Article 4 Direction or another restriction1.
Why it matters for households
Certification is not only a quality mark here. For an air source heat pump installed under permitted development, compliance with the named planning standard is what keeps the installation outside the planning application process1. From 28 May 2026 the choice of certification route narrows to one scheme, so the paperwork an installer produces becomes the evidence that the planning condition is satisfied. Households in listed buildings or scheduled monument sites are outside these rights altogether and Richmond advises that listed building consent is needed for any type of heat pump2. Guidance on the Planning Portal covers England; policy in Wales may differ1.
What happens next
The change takes effect on 28 May 20261. No further steps or transitional arrangements are set out on either page. Richmond's pre-application service is free where an application relates to promoting sustainable development, which includes heat pump installations2.
Sources2 cited
- Planning Permission: Air source heat pump - Heat pumps - Planning Portal, planningportal.co.uk
- Planning guidance for heat pumps - London Borough of Richmond upon Thames, richmond.gov.uk