Does air conditioning need planning permission? The rules and the exceptions

When is an air conditioning unit permitted development?

When it is an air source heat pump that meets every condition on the Planning Portal's list. If you can answer yes to all of these, no application is needed:

1. Will it provide warmth in winter too, rather than cooling alone?
2. Is it installed to MCS 020a, including its noise calculation? MCS 020a has been the only certification route since 28 May 2026.
3. Is the outdoor unit 1.5 cubic metres or smaller on a house, or 0.6 cubic metres or smaller on a block of flats?
4. Is it the first outdoor unit on the property? A semi, a terrace or a block of flats is allowed one; a detached house is allowed two.
5. If it serves a block, is the building made up entirely of flats, with no commercial premises in it?
6. Is it off any pitched roof, and, on a flat roof, set back a metre or more from every edge?
7. If it goes on a wall facing a road, is it at ground-floor level?
8. Has it been placed, as far as practicable, to limit its effect on how the building looks?

Two further conditions stay with it: once microgeneration no longer needs it, it has to be removed as soon as is reasonably practicable, and the rights themselves can be removed by a planning condition or an Article 4 direction. Source: Planning Portal.

Why does a cooling-only unit need an application?

Because the right exists for heat pumps. SI 2025/560, in force since 29 May 2025, made it a condition that the heat pump is not used only for cooling. The same order let a house take a bigger outdoor unit (now 1.5 cubic metres at most; it had been 0.6), gave detached houses a second unit and dropped the old requirement to keep a metre from the boundary. Baxi's summary of the change says plainly that air-to-air heat pumps can now benefit. A reversible split qualifies; a model that only cools does not, however small. Check that the model on your quote heats as well. Sources: SI 2025/560; Baxi.

What is the 37 dB(A) noise test?

A calculation done before fitting, not a reading taken afterwards. The installer predicts how loud the outdoor unit will be 1 metre in front of the centre of the nearest window or door to a habitable room next door, starting from the sound power on the unit's energy label and allowing for distance, nearby hard surfaces and any solid barrier. At 37 dB(A) or below, the condition is met; above it, an application is needed. The noise guide goes through the steps. Sources: Grant UK; IOA and CIEH.

What extra limits apply in a conservation area?

The front of the house is ruled out. Inside one, an outdoor unit is barred from every wall and roof facing onto a highway, and from any spot closer to a bounding highway than the house is. (Outside conservation areas a road-facing wall can still take one at ground-floor level.) Redbridge has 16 conservation areas, from Valentines Mansion, designated in 1981 on the edge of central Ilford, to the Woodford, Wanstead and Snaresbrook groups covered on the Woodford page. In the Bungalow Estate, south of Seven Kings between Ilford and Goodmayes, designated as Mayfield on 3 October 1991, an Article 4 direction has controlled extensions, porches and roof alterations since September 1987, and the council lists a further direction for the estate from 2017, so we confirm the current controls with Redbridge's planners before quoting there.

Sources: Planning Portal; Redbridge Council; Redbridge conservation area proposals; Bungalow Estate appraisal.

How does an Article 4 direction change things?

It switches off specific permitted development rights across a mapped area, so jobs that would otherwise be allowed need an application, and each direction names different classes. Gidea Park's, in force since 31 December 2015 and confirmed in June 2016, covers the houses in its conservation area at two levels. Level 1 controls extensions, alterations and roof changes at the front and sides; Level 2, the stronger, carries those controls round to the rear and adds porches, boundary walls and gates, and even painting the outside. The direction does not name heat pumps, but Havering's 2025 management plan for Gidea Park (in the February 2025 draft, adopted that September) asks for new external devices to be kept to rear elevations. Across the Essex border the picture is lighter: Epping Forest's list of directions includes none in Chigwell or Grange Hill, although Chigwell Village, designated on 2 October 1969, is still a conservation area. See the Gidea Park and Chigwell pages. Sources: Havering Council, Article 4; Gidea Park management plan; Havering consultation hub; Epping Forest District Council; planning.data.gov.uk.

Do Waltham Forest and Hackney take a different line?

Yes: both councils lean away from air conditioning in their guidance. Waltham Forest's Residential Alterations and Retrofit guidance, adopted on 11 June 2026, says mechanical ventilation with heat recovery (MVHR) "is considered over air conditioning", wants air source heat pumps in rear gardens wherever possible, keeps them off pitched roofs and says a heat pump in a front garden in a conservation area always needs permission. In Hackney, the September 2025 draft of the extensions and alterations guidance said residential air conditioning units are "typically not acceptable" and sent readers to the retrofit guidance for cooling; the extensions and alterations guidance was adopted in December 2025 and took effect in January 2026, so check the adopted wording before relying on the draft. Across London, policy SI 4 of the London Plan asks major developments to work down a cooling hierarchy in which active cooling comes last. The Walthamstow and Hackney pages give the local detail. Sources: Waltham Forest Council, adoption; Waltham Forest Council, heating and cooling; Hackney Council draft; Hackney Council, adoption; London Plan.

What about flats?

A block gets one outdoor unit under permitted development, of no more than 0.6 cubic metres, and only where the building is entirely flats; a flat above a shop needs an application. Planning is only one gate, because the freeholder's consent under the lease is a separate matter, and in Ilford it is a common one: 55% of households in Ilford Town ward live in flats. If the block's one unit is already taken or the freeholder refuses, a through-wall monobloc may still be possible. Sources: Planning Portal; LEASE; Area Insights.

Do listed buildings, shops and offices need an application?

Both usually mean an application. Permitted development does not apply within the curtilage of a listed building, any work affecting its character needs listed building consent, and carrying such work out without consent is a criminal offence. Historic England's 2023 draft advice suggested heat pumps would generally be acceptable at listed buildings if sympathetically sited; that describes a likely outcome, not an exemption from consent. On shops, offices and other buildings that are not homes, the Planning Portal expects an application to be needed in most cases, and Mishcon de Reya notes that an unauthorised unit can attract an enforcement notice, typically requiring it to be moved or removed. Our Ilford air conditioning homepage sets out the wider local picture. Sources: Planning Portal; section 7; section 9; The Construction Index; Planning Portal; Mishcon de Reya.