Do You Need Planning Permission for Air Conditioning? 2026 Rules for London Homes

Last updated: 3 October 2026

See it for your own home: put in your address and get free concept drawings and an indicative price. Get my free concept → Or see our Planning Applications →

Sometimes. In England the answer turns on one condition most homeowners have never heard of: permitted development for an outdoor air conditioning unit only applies if the equipment is not used solely for cooling. A system that heats as well as cools, complies with the MCS Planning Standards and stays inside the limits set out below can usually go in without a planning application. A cooling-only system cannot, and needs planning permission.

That single condition explains why the same question produces different answers in different houses, and why the answer your installer gives may not match your borough's. This guide sets out the rules as they stand in 2026, what changes in a conservation area or a listed building, and why we treat air conditioning as the last answer to overheating rather than the first.

The short answer

• Heating and cooling, within the limits: permitted development. No planning application.
• Cooling only: not permitted development. You need planning permission.
• Conservation area: Planning Portal advises that permission will be required. The legislation is narrower than that, but plan for an application and confirm with your borough.
• Listed building or its curtilage: no permitted development at all. Listed building consent is needed.
• Flats: the heat pump class does apply to blocks of flats, with a smaller size cap, but as a leaseholder you will also need the freeholder's consent or a licence to alter.

Why the heating function decides it

The permitted development right for an outdoor unit sits in the air source heat pump class of the General Permitted Development Order (Schedule 2, Part 14, Class G). That class was amended in May 2025, and the current version turns on a condition that replaced the old “solely for heating purposes” wording: the equipment must not be solely used for the purpose of cooling.

So the practical test is about the equipment, not the wall. If you are installing a reversible system that provides heating as well as cooling, and it complies with the MCS Planning Standards, it can fall inside permitted development. If it only cools, it does not, and a planning application is required. Planning Portal states this directly in its own guidance on air conditioning, and the class itself is Schedule 2, Part 14 of the General Permitted Development Order 2015. Establishing which of the two you are installing is the single most useful thing to do before you order equipment.

That also means the labelling matters. A domestic “air conditioning” unit sold as comfort cooling is usually a cooling-first product; whether it is also a compliant heat pump is a question for the installer and the specification sheet, not the brochure.

The permitted development limits

If the heating-function condition is met, the installation must still stay inside these limits. They apply to the outdoor compressor unit and its housing.

What changed in May 2025, because much of the advice online is out of date. The rule that an outdoor unit had to be at least 1 metre from your boundary was removed for air source heat pumps. The size cap for a house rose from 0.6 m³ to 1.5 m³, a detached house may now have up to two units, and the requirement that the pump be used solely for heating was replaced by the prohibition on cooling-only use. If you are reading a guide that quotes the 1 metre boundary rule as current law, it has not been updated.

Extensions, lofts and garden rooms

The class covers the dwellinghouse and land within its curtilage, including a building in the curtilage. In practice that means an outdoor unit fixed to the wall of a new extension is still on the dwellinghouse, and a condenser serving a garden room or outbuilding inside the curtilage is inside the class too, subject to the same limits. A garden room is not a loophole.

Three situations need care:

• A wall that fronts the street. Above ground-floor level, a unit on a highway-facing wall is excluded outside a conservation area, and inside one it is excluded at any height.
• Roof plant. A pitched roof is excluded outright, and a flat roof only works if the unit sits more than a metre from the outer edge. Loft plant also needs an external terminal and a condensate route that will not cause a nuisance — agree the position on the drawings rather than on site.
• A scheme that already needs permission. If the extension or loft conversion itself requires a planning application, put the unit on those drawings. An approved scheme can include the plant position, which avoids a second application later.

The rules for the unit are separate from the rules for the extension. An extension can be permitted development while the condenser is not, and the other way round.

Conservation areas, listed buildings and Article 4 directions

London has a high concentration of conservation areas, listed buildings and Article 4 directions, so this is where most of the difficulty sits.

Conservation areas. Planning Portal's guidance says plainly that if your home is in a protected area such as a conservation area, permission will be required. The legislation is more permissive than that, but only on two conditions: the unit must not be on a wall or roof that fronts a highway, and it must not be nearer the highway than the nearest part of the building. In an inner-London terrace, those conditions often fail. Plan for an application and get your borough's view in writing.

Listed buildings. Permitted development does not apply to a listed building or to land and buildings within its curtilage, so an external condenser on a listed house needs listed building consent as well as any planning permission. Consent is about whether the works would affect the building's character as a building of special architectural or historic interest, and a visible box on a principal elevation is exactly the kind of detail a conservation officer will look at.

Article 4 directions. A direction withdraws specified permitted development rights in a defined area. Whether one covers your street is a question for the borough's Article 4 map, and it is the first thing to check if your property is in a conservation area or a sensitive street. Our guide to what you can build at my address covers how the rules vary by borough.

Flats. The heat pump class does extend to blocks of flats, with the smaller 0.6 m³ cap. The additional obstacle is legal rather than planning: most leases require the freeholder's consent to fix equipment to a communal wall, and managing agents will usually ask for a licence to alter. That is a separate process from planning permission and it runs on its own timetable.

Building regulations, F-gas and who may install it

Planning Portal advises that an air conditioning installation must comply with building regulations, and that you should use an installer who belongs to the Microgeneration Certification Scheme or the relevant Competent Person Scheme. In practice, four separate things can be in scope:

• Electrical safety. Work in a dwelling must comply with Part P and be certified by a registered electrician. A new circuit or a new outdoor supply is notifiable work.
• Refrigerant handling. This is regulated separately from building control. The technician working on the refrigerant circuit must hold current F-gas certification and the business must be registered, because the refrigerant is a fluorinated greenhouse gas.
• Structure. A unit on a roof, a frame or a bracket fixed into a structural wall may need a structural check, particularly on a period property with a rendered or solid-brick façade.
• Ventilation. Part F applies if the installation changes how the house is ventilated. Part O, the overheating regulation, applies to new residential buildings; it does not normally apply to a retrofit in an existing house, which is one reason a new extension or loft is where overheating should be solved.

Ask for the certification before work starts, not after. It is the difference between an installation that is signed off and one that becomes a problem when you sell.

Noise: the complaint that outlives the permission

The permitted development conditions require the unit to be sited so as to minimise its effect on the amenity of the area. Noise is a material planning consideration, and boroughs can and do impose conditions on plant noise. Separately, a neighbour can raise noise as a statutory nuisance under the Environmental Protection Act 1990 whether or not you had planning permission — a permission does not immunise you from a nuisance complaint.

The practical measures are unglamorous and effective: site the condenser away from a neighbour's bedroom window and from a shared boundary, check the manufacturer's sound power figure rather than the marketing decibel claim, use anti-vibration mounts on a bracket, and avoid a position where the unit's exhaust faces a neighbour's opening window. On a London terrace, the space between two houses is often the quietest place for the household and the loudest place for next door.

Design it out first: the Suddeco position

Overheating is a design problem before it is an equipment problem. The order that works is: orientation and layout, glazing ratio, external shading, solar control glass, cross-ventilation, then active cooling. Our cooling guide sets out what each step costs — published pricing puts solar control glass at £250–£450 per m², roughly £50–£100 per m² more than standard double glazing — and a correctly sized overhang or external blind has no running cost at all.

We are stating our position plainly: Suddeco Homes does not install air conditioning as a standalone service. We design and build extensions, lofts and full-house renovations across Greater London, and we would rather design a room that does not need cooling than sell you equipment to fix a design problem. We design it, we build it. Where cooling is the honest answer — a west-facing bedroom under a dark roof, a study over a busy road — we will say so, and we will design the first fix: a dedicated supply, a condensate route and a sensible external position, so the unit can be added later without opening up the finished room.

That is also why this page answers the permission question rather than recommending equipment. If your project is an extension or a loft, the cheapest cooling decision you will make is the one you take at design stage. Our guides to overheating and cooling in London homes, rear extension cost in London and loft conversion cost in London cover the design side.

Getting a definitive answer for your address

Generic guidance cannot tell you whether your wall fronts a highway, whether an Article 4 direction covers your street, or whether your unit is a compliant heat pump or a cooling-only appliance. Three ways to get certainty before you spend:

• A Lawful Development Certificate. Our planning guides put the fee for a proposed householder LDC at £103. It is written proof that the installation is lawful under permitted development, and it is worth having if you are in a conservation area or planning to sell.
• Your borough's view, in writing. Most London boroughs offer pre-application advice, with a fee set by the borough. A short written response on the siting of a condenser is usually enough.
• A settled design. If the unit is part of an extension, loft or renovation, decide the position while the drawings are live. Our Concept package at £995 gives measured drawings, and Design + Planning at £2,495 covers planning applications, building regulations drawings and structural engineering. Design to Build, where we build it at a fixed quote, starts at £4,500. We work across Greater London only.

If you would rather solve the heat before you buy the equipment, get in touch and we will tell you what your address can take.

Frequently asked questions

Do you need planning permission for air conditioning in the UK?

It depends on whether the equipment provides heating. In England, permitted development for an outdoor air source heat pump covers a system that is not solely used for cooling, complies with the MCS Planning Standards and stays within the limits on size, number and siting. A cooling-only system is not permitted development, so planning permission is required. Planning Portal states this in its air conditioning guidance.

Do I need planning permission for air conditioning if the system only cools?

Yes. The permitted development class applies only where the equipment is not solely used for the purpose of cooling. A cooling-only comfort unit falls outside it, so a planning application is required before installation.

What are the permitted development limits for an outdoor air conditioning unit?

The unit must not be solely for cooling and must comply with the MCS Planning Standards. One unit is allowed on a house that is not detached, or on a block of flats, and up to two on a detached house. The outdoor unit and its housing must not exceed 1.5 m³ on a house or 0.6 m³ on a block of flats. It must not be on a pitched roof, and on a flat roof it must be more than 1 metre from the outer edge. It must not sit on a wall fronting a highway above ground-floor level, and in a conservation area or World Heritage Site it must not be on a wall or roof fronting a highway or nearer the highway than the building. It must be sited to minimise the effect on appearance and amenity, and removed when no longer needed.

Do I need planning permission for air conditioning in a conservation area?

Planning Portal advises that permission will be required in a protected area such as a conservation area. The legislation allows the unit in a conservation area only if it is not on a wall or roof fronting a highway and not nearer the highway than the nearest part of the building, which many inner-London terraces fail. Plan for an application and confirm the position with your borough.

Does a listed building need listed building consent for air conditioning?

Yes. Permitted development does not apply to a listed building or to buildings and land within its curtilage, so an external condenser needs listed building consent as well as any planning permission. Consent depends on whether the works would affect the building's character as a building of special architectural or historic interest.

Do you need planning permission for air conditioning on an extension, loft or garden room?

The same class covers the dwellinghouse and land within its curtilage, including a building in the curtilage, so an outdoor unit on a new extension wall or serving a garden room is treated the same way, subject to the size, roof, highway and siting limits. Roof plant is the usual failure point: pitched roofs are excluded, and a flat roof needs the unit more than 1 metre from the edge. If the extension itself is going through planning, put the unit on those drawings.

Does air conditioning need building regulations approval or a certified installer?

Planning Portal advises that the installation must comply with building regulations, and recommends an installer in the Microgeneration Certification Scheme or the relevant Competent Person Scheme. Electrical work must comply with Part P and be certified, refrigerant work must be carried out by an F-gas certified technician working for a registered business, and structural or ventilation work can bring further approvals into scope.

Is the 1 metre boundary rule for an outdoor unit still required?

No. The requirement that an air source heat pump be at least 1 metre from the boundary of the curtilage was removed in May 2025. The same amendment raised the size cap for a house from 0.6 m³ to 1.5 m³, allowed up to two units on a detached house, and replaced the “solely for heating purposes” condition with the rule that the equipment must not be solely used for cooling. Guides still quoting the 1 metre rule are out of date.