Do you need planning permission for air conditioning in London?

Why this question has a new answer

For years the simple answer in London was that air conditioning needed planning permission. That changed on 29 May 2025, when the government amended the permitted development rules for air source heat pumps in England. The change matters because most modern split air conditioners are reversible. They can heat as well as cool, which makes them air to air heat pumps in planning terms.

The rules sit in Part 14, Class G of the General Permitted Development Order. The Planning Portal summarises them, and Planning Geek sets out the full wording and the 2025 changes.

The one condition people miss: not cooling only

Class G carries a condition that the heat pump is “not used solely for cooling”. A unit you install to heat and cool your home can fit within the rules. A unit installed purely to cool a bedroom in summer does not, however quiet or small it is. If you only want cooling, plan on a planning application.

This is also why we ask at the survey whether you intend to heat with the system. It changes the planning route, the sizing and whether a grant might ever apply.

The Class G limits in plain English

If your unit will heat as well as cool, it still has to meet every one of these limits.

Rule	What it means for you
Noise	The unit must meet the MCS 020(a) planning standard: a calculated 37 dB(A) or less, 1 metre outside the nearest neighbour’s habitable room window or door
Size	Outdoor unit up to 1.5 cubic metres on a house, 0.6 cubic metres on a block of flats
Number	One unit on a terraced or semi detached house or a block of flats; two on a detached house
Roofs	Not on a pitched roof; on a flat roof, at least 1 metre from the edge
Listed buildings	Not permitted at a listed building or scheduled monument
Conservation areas	Not on a wall or roof that fronts a highway, and not nearer the road than the house
Elsewhere	Not above ground floor on a wall that fronts a highway
Siting	Placed, as far as practical, to limit its effect on the look of the building and the area

The 1 metre boundary rule was removed in 2025, so a unit can now sit close to the fence if the noise calculation still passes.

Restrictions that override permitted development

Permitted development can be removed. An Article 4 direction, a condition on an earlier planning permission or a restriction on a modern estate can mean you need to apply anyway. Hounslow, for example, has Article 4 directions covering the Bedford Park and Gunnersbury conservation areas. Your council’s planning team can tell you whether one applies to your street.

Flats are a special case

The rules apply to a house or a block of flats, not to one flat on its own. A block of flats only gets one heat pump in total, and the building must be wholly flats, so a block with shops on the ground floor is outside Class G. With 54% of London households living in flats according to the 2021 Census, this is why so many London jobs need a planning application. Our guide to air conditioning in a London flat goes through it in detail.

Richmond: detached houses and 85 conservation areas

Richmond upon Thames is a good example of how the rules play out. The borough has 85 conservation areas, from Richmond Hill and Kew Green to Twickenham Riverside and Barnes. It also has more detached houses than inner London, and a detached house can have two units under Class G. So a family in a detached house in East Sheen or St Margarets may be able to fit two reversible units at the back with no application, while a neighbour in a Kew conservation area terrace needs to keep the unit off the street side and may still need to apply.

The Richmond area page has more on the local housing and the kind of positions that usually work.

Noise is where most applications are won or lost

Even when you do need permission, most heat pump applications are approved. A September 2026 Nesta analysis cited by Planning Geek found 83% of residential heat pump applications in its dataset were accepted and fewer than 7% refused, with sound the most common reason for refusal. That fits what London councils ask for. Westminster’s noise guidance wants plant noise 10 dB below the lowest background level in noisy areas, and Kensington and Chelsea’s Local Plan resists plant, including air conditioning units, with an unacceptable noise impact.

A good application includes the unit’s published sound power level, the distance to the nearest window, any wall or fence that blocks line of sight, and the resulting calculation.

Getting certainty before you spend

If you think your installation is permitted development but want it confirmed, you can apply to the council for a Lawful Development Certificate. It costs time and a fee, but it gives you a written decision you can show a buyer later. Ask your installer for the completed MCS 020 noise calculation either way. Without it, “no planning needed” is only an opinion.

The other consents to check

Planning is not the only permission:

• Freeholder consent if you own a leasehold flat.
• Landlord permission if you rent.
• Listed building consent for any listed home.
• Part P sign off for the new electrical circuit.
• F-gas: the engineer must hold an F-gas qualification and the company must be certified by an approved body, as set out on gov.uk.

We check the planning route at the survey and tell you which applies before you pay for anything. See how that works on our home air conditioning page.