Do you need planning permission for air conditioning?

The short answer

In planning law, air conditioning that can heat your home is an air source heat pump. Installing one on a house or a block of flats in England is permitted development under Class G of Part 14 of the General Permitted Development Order 2015. Permitted development means you don't need to apply for planning permission, as long as every limit and condition is met.

The Town and Country Planning (General Permitted Development) (England) (Amendment) Order 2025, SI 2025/560, rewrote those rules from 29 May 2025. Since then, a unit that heats and cools can qualify, but a cooling-only unit can't. If any rule below isn't met, you need full planning permission.

What changed on 29 May 2025

A guide that mentions a 1 metre boundary rule or a 0.6 m³ limit for houses is out of date. These are the changes, as the explanatory memorandum to SI 2025/560 describes them.

• The rule banning units within 1 metre of the property boundary was removed
• The outdoor unit limit for a house rose from 0.6 m³ to 1.5 m³. Blocks of flats stay at 0.6 m³
• A detached house can now have two heat pumps. Other houses and blocks of flats can have one
• The old condition that a heat pump be used solely for heating was replaced. Now it must not be used solely for cooling, which brings heating-capable air conditioning into the rules
• The noise standard is now MCS 020(a), with no option to use an equivalent standard

The permitted development rules for a house

From Class G as it stands today. Your installation must meet every one of these to avoid a planning application.

• The unit heats as well as cools. Class G condition G.3(aa): it must not be used solely for cooling
• It meets the MCS Planning Standards, now MCS 020(a), the noise calculation (G.1)
• No more than one heat pump on, or within the grounds of, a semi-detached or terraced house, or two on a detached house (G.2(a))
• The outdoor unit, including any housing, is no bigger than 1.5 m³ (G.2(d))
• It isn't on a pitched roof, or on a flat roof within 1 metre of the roof's edge (G.2(f) and (g))
• The house isn't a listed building, and the site isn't a scheduled monument (G.2(h) and (i))
• There's no wind turbine on the building or in the grounds (G.2(b) and (c))
• In a conservation area or World Heritage Site: not on a wall or roof that fronts a highway, and no nearer to a bordering highway than the house itself (G.2(j))
• Elsewhere: not on a wall that fronts a highway, above ground-floor level (G.2(k))
• Sited, so far as practicable, to minimise its effect on the look of the building and on the amenity of the area (G.3(b) and (c))
• Removed as soon as reasonably practicable when it's no longer needed (G.3(d))

The noise rule: MCS 020(a)

MCS 020(a), Air Source Heat Pump Sound Calculation (For Permitted Development Installations), has applied to permitted development installs since 20 September 2025. It sets a limit of 37 dB(A) at each assessment position. Many guides still quote 42 dB(A), a figure from the earlier version of the standard.

An assessment position is 1 metre outside the centre of a door or window to a habitable room of a neighbouring property. Habitable means rooms for living or sleeping, not bathrooms, hallways or utility rooms. On a block of flats, the other flats in the same block count as neighbours.

The calculation uses the unit's sound power level from the manufacturer, the distance to each neighbouring window, nearby walls that reflect sound and any solid barrier in between. Every neighbouring window that could be affected has to come out at 37.0 dB(A) or lower. If a position fails, moving the unit or adding a barrier can sometimes fix it. We give you the manufacturer's sound data for the model we quote.

Flats and leasehold homes

Class G does cover blocks of flats, despite what some guides say. The limits are tighter: one heat pump per block, on or within the grounds of the block, with an outdoor unit no bigger than 0.6 m³. If the block already has one, a second needs planning permission. Most outdoor units for one or two rooms are well under 0.6 m³, but always check the model's height, width and depth.

Planning is only half of it. Most leases need the freeholder's written consent for alterations, often called a licence for alterations, whatever the planning position. Apply early, because freeholders and managing agents can take weeks to reply and may charge a fee. Our flats page explains how to put the request together.

Conservation areas, listed buildings and Article 4 directions

In a conservation area, you can still use permitted development for a unit at the back or side of the house, as long as it isn't on a wall or roof facing a highway and isn't closer to a bordering highway than the house. Your council's website has a map of its conservation areas.

If your house or block is a listed building, Class G doesn't apply at all. You need planning permission, and usually listed building consent too. You can check whether a building is listed on Historic England's National Heritage List.

Councils can also remove permitted development rights in an area with an Article 4 direction, and some planning permissions, often on newer estates, include a condition that removes them. Check with your council if you're not sure.

Do I need to apply? A quick decision table

For a heating-capable split system on a home in England. Each row assumes every other rule is met.

This guide covers homes. Offices, shops and other business premises follow different rules, so ask the council.

When you need planning permission, and how to apply

If your installation falls outside Class G, you apply to your council, usually through the Planning Portal. A householder application normally needs drawings showing the unit's position, the manufacturer's details and often a noise report. Councils normally have 8 weeks to decide a householder application, and can attach conditions to an approval, such as a noise limit at the nearest neighbour.

Installing without permission when you needed it is a planning breach. The council can take enforcement action and require the unit to be removed. Checking first costs far less than moving a unit later.

Lawful Development Certificates

If you're confident your installation is permitted development but want it in writing, you can apply to the council for a Lawful Development Certificate for a proposed development, under section 192 of the Town and Country Planning Act 1990. There's a fee, so check your council's current charge.

It isn't compulsory, but it's useful when a case is borderline, such as a corner plot or a tight noise calculation, and when you come to sell.

Building Regulations and F-Gas

Planning isn't the only rule. Under Part P of the Building Regulations, adding a new electrical circuit in a home is notifiable work. It must be certified by an electrician registered with a competent person scheme, or approved by building control. Connecting to a suitable existing fused spur usually isn't notifiable.

Handling refrigerant is restricted to F-Gas certified engineers. Our engineers are F-Gas certified, and the refrigerant in your system is recorded when we commission it.

Planning permission questions