Do You Need Planning Permission for Air Conditioning in the UK?

Most domestic air conditioning installations in the UK don't need planning permission. But there are conditions, and they're more specific than you'd think. Get one wrong and your local council can make you remove the unit entirely.

I've seen it happen. A homeowner installs a cooling-only unit thinking they're covered under permitted development, and six months later the council sends an enforcement notice. The rules aren't complicated, but they are precise. Here's exactly what you need to know before you book an air conditioning installation.

The Actual Rules: GPDO 2015, Part 14, Class G

The legislation that governs domestic air conditioning installations is the General Permitted Development Order 2015, Schedule 2, Part 14, Class G. This is what determines whether your installation counts as "permitted development" or whether you need to apply for planning permission.

Here's where most websites get it wrong. If you search for this topic online, you'll see the figure 0.6 cubic metres quoted everywhere as the maximum size for a domestic outdoor unit. That's incorrect for houses. The 0.6 cubic metre limit only applies to flats.

Size Limits

Property Type	Max Volume Per Unit	Max Number of Units
Detached house	1.5 cubic metres	2
Semi-detached or terraced house	1.5 cubic metres	1
Flat	0.6 cubic metres	1

For context, most residential outdoor units from Daikin, Mitsubishi, and Samsung sit well under 0.6 cubic metres anyway. So even the flat limit is unlikely to be a problem for a standard wall-mounted split system. But if you're looking at a larger multi-split or a ceiling cassette with a beefier condenser, it's worth measuring.

Placement Rules

• The unit cannot be installed on a pitched roof. Full stop. No exceptions.
• On a flat roof, the unit must be at least 1 metre from any external edge of the roof.
• The unit must not project above the highest part of the roof (excluding the chimney).

These placement rules are non-negotiable under permitted development. If you can't meet them, you need to apply for planning permission.

The "Not Solely for Cooling" Rule

This is the one nobody talks about. And honestly, it's the one that catches people out the most.

Under Class G, the installation is only permitted development if the unit is not solely for the purpose of cooling. In practice, this means you need a reversible heat pump system that provides both heating and cooling. A cooling-only unit always requires planning permission, regardless of its size or placement.

Read that again, because it matters. If you install a cooling-only air conditioner on your house, you are not covered by permitted development rights. Even if it's tiny. Even if it's on the ground. You need planning permission.

The good news is that virtually every modern split system from the major manufacturers is already reversible. Daikin, Mitsubishi Electric, Fujitsu, Samsung, LG, Toshiba. They all produce heating and cooling as standard. But some older units or specialist commercial equipment might be cooling-only. We always check this during our domestic installation survey.

There's a practical reason behind this rule too. The government wants to encourage heat pump adoption. A reversible air conditioner is technically an air-source heat pump. By restricting permitted development to reversible systems, they're steering homeowners toward equipment that can reduce gas boiler dependence.

Noise Limits: MCS 020 and London Requirements

Even if your installation qualifies as permitted development in every other way, noise can still be a problem. The relevant standard is MCS 020, which sets out noise requirements for micro-generation equipment including air-source heat pumps.

Current and Upcoming Noise Limits

The current MCS 020 standard requires that noise from the outdoor unit does not exceed 42 dB LAeq at the nearest neighbour's window or door. From May 2026, this drops to 37 dB LAeq, which is a significant reduction.

To put that in perspective, 42 dB is about the level of a quiet library. 37 dB is closer to a whisper. Modern inverter-driven units from the likes of Daikin and Mitsubishi can achieve these levels, but positioning matters. Putting the condenser right next to a neighbour's bedroom window is a recipe for complaints, regardless of the dB reading on the spec sheet.

London Borough Requirements

Several London boroughs have their own, stricter noise rules. Westminster, Kensington and Chelsea, and Greenwich all require that the unit operates at 10 dB below the existing background noise level. In a quiet residential street at night, that can mean your unit needs to run at 25-30 dB, which is extremely quiet.

This doesn't mean you can't install air conditioning in these boroughs. It means we need to plan carefully. Unit selection, positioning, acoustic enclosures, and anti-vibration mounts all play a part. On some jobs we've used water-cooled systems specifically to eliminate outdoor noise entirely.

Conservation Areas and Listed Buildings

Conservation Areas

If your property is in a conservation area, you still have permitted development rights for air conditioning. But there's an extra condition: the unit cannot be installed on a wall or roof that faces a highway. "Highway" in planning terms includes any public road, footpath, or bridleway.

So if your front wall faces a street, the condenser needs to go on the side or rear. If you're on a corner plot with two highway-facing elevations, your options narrow further. We deal with conservation area installations regularly across central London and always confirm the positioning with the local planning authority before work starts.

Listed Buildings

Listed buildings are different altogether. You always need planning permission for a listed building. No exceptions. No permitted development. And on top of standard planning permission, you also need Listed Building Consent, which is a separate application.

Listed Building Consent covers any alterations that affect the character of the building. Drilling through a 200-year-old brick wall, mounting brackets onto period stonework, running trunking across a heritage facade. All of this needs formal approval.

We've fitted air conditioning in listed buildings across London. It can be done, but it requires early engagement with the conservation officer, careful specification of materials and methods, and sometimes alternative system designs. Water-cooled systems are often the best option here because they avoid the need for an external condenser unit entirely. You can read more about that on our water-cooled air conditioning page.

Article 4 Directions

An Article 4 Direction is a tool that local councils can use to remove permitted development rights in a specific area. If your property is covered by one, the rules above don't apply. You need planning permission regardless of system type, size, or placement.

Article 4 Directions are most common in conservation areas, but they can apply anywhere. Some councils use them broadly, others are very targeted. The only way to know is to check with your local planning authority. Don't assume. I've seen properties on the same street where one house has full PD rights and the next door needs a full application because the Article 4 boundary runs between them.

Commercial Properties

Everything above relates to domestic properties. Commercial air conditioning operates under a completely different planning framework, and the rules are generally more relaxed for smaller systems.

For commercial installations, the key considerations are:

• Noise: Still a major factor, especially in mixed-use buildings or near residential properties.
• Listed buildings and conservation areas: Same rules as domestic. Full permission required.
• TM44 inspections: Any commercial air conditioning system with an effective rated output of over 12 kW must have regular TM44 energy inspections by an accredited assessor. This isn't planning related, but it's a legal requirement that many business owners don't know about.
• Change of use: If you're converting a space and changing its use class, the air conditioning installation may need to be included in the overall planning application.

If you're fitting air conditioning in an office, shop, restaurant, or any other commercial premises, we cover the full planning and regulatory picture during our commercial installation survey.

Building Regulations: Separate from Planning

Planning permission and building regulations are two completely different things. You can have full permitted development rights and still need to comply with building regulations. They run in parallel.

Part P: Electrical Safety

Air conditioning installation is notifiable electrical work under Part P of the Building Regulations. This means it must be carried out by a competent person registered with an approved scheme, or you need to get building control approval separately. All our engineers are Part P registered, so this is handled automatically.

Part L: Energy Efficiency

Part L sets minimum energy efficiency standards. For air conditioning, this means the system must meet certain seasonal efficiency ratings (SEER for cooling, SCOP for heating). All current models from major manufacturers meet these requirements, but it's worth knowing the regulation exists.

F-Gas Certification

Anyone handling refrigerant gases must hold F-Gas certification. This is a legal requirement under the EU F-Gas Regulation (retained in UK law post-Brexit). It's not a building regulation strictly speaking, but it's a legal requirement that sits alongside them.

If an installer can't show you their F-Gas certificate, walk away. Working with refrigerants without certification is illegal, and it means your warranty won't be valid either. Our full credentials are on our about us page.

How to Check If You Need Planning Permission

Here's a simple process to work through before your installation.

Step 1: Check Your Property Status

• Is it a listed building? If yes, you need planning permission and Listed Building Consent. No further checks needed.
• Is it in a conservation area? If yes, the highway-facing restriction applies.
• Is there an Article 4 Direction? If yes, you need planning permission.

Step 2: Check the System

• Is the unit reversible (heating and cooling)? If it's cooling-only, you need planning permission.
• Is the outdoor unit within the size limit for your property type?
• Does the number of units comply? (Two for detached, one for everything else.)

Step 3: Check the Placement

• Not on a pitched roof.
• If on a flat roof, at least 1 metre from the edge.
• Not projecting above the roofline.

Step 4: Check for Conflicts

• Do you already have a wind turbine installed under permitted development? If yes, you can't also have an air conditioning unit under PD rights. You'd need planning permission for the AC.

Step 5: Contact Your Local Planning Authority

If you're unsure about any of the above, call your local planning authority (LPA). They have a duty to provide pre-application advice. Many offer this for free for householder queries.

For absolute certainty, you can apply for a Lawful Development Certificate. This is a formal confirmation from the council that your proposed installation is permitted development. It costs around £100-£200 and takes a few weeks, but it gives you a legal document you can rely on if anyone ever questions the installation.

What If You Need to Apply for Planning Permission

If your installation does require planning permission, here's what to expect.

The Application

You'll submit a householder planning application through the Planning Portal. The standard determination period is 8 weeks, though straightforward cases sometimes come back sooner.

Documents You'll Typically Need

• Application form and fee (currently £258 for a householder application in England)
• Site location plan (1:1250 or 1:2500 scale)
• Block plan showing the proposed unit location
• Elevations showing the unit on the building
• Noise assessment (especially in residential areas or near sensitive receptors)
• Heritage statement (if the property is listed or in a conservation area)
• Manufacturer specification sheet for the unit

Approval Conditions

Even when permission is granted, it often comes with conditions. Common ones include maximum noise levels, operating hours, specific paint colours to match the building, and requirements to remove the unit if it's no longer needed.

We can help with the technical side of planning applications. We provide unit specifications, noise data, and installation drawings. The formal application itself is usually best handled by a planning consultant or architect, especially for listed buildings.

Don't Leave It to Chance

The planning rules around air conditioning are more nuanced than most people expect. The biggest mistakes I see are people installing cooling-only units thinking they're covered, and people in Article 4 areas who didn't check. Both end up with enforcement notices and removal costs.

If you're thinking about air conditioning for your home or business, we'll check all of this during our initial survey. We confirm the planning position, building regulation requirements, and noise compliance before we quote. No surprises after the install.

Get in touch through our contact page or call us directly. We'll tell you exactly where you stand before any work starts.

Ali Elm, Head of Operations, Be Cool Refrigeration