Safety, certificates and compliance, 29 October 2026
Air conditioning and planning permission: when you need it
On a house in England, air conditioning usually doesn't need planning permission if the system also provides heating (an air-to-air heat pump), the outdoor unit is no bigger than 1.5 cubic metres, it meets the MCS 020a noise standard, and it isn't on a pitched roof or a listed building. Cooling-only units, commercial premises and conservation-area frontages normally need permission.
Why does heating make the difference?
Because the planning right is for heat pumps, not air conditioning. The permitted development right in England (Class G of Part 14 of the General Permitted Development Order) covers "microgeneration air source heat pumps". Until May 2025 it was effectively limited to units providing heat. The 2025 amendment changed the condition to "not solely used for the purpose of cooling", which brought air-to-air units that heat and cool inside the right.
So a reverse-cycle split system, sold and set up to heat the room as well as cool it, can be permitted development. A cooling-only unit can't. The Planning Portal puts it plainly: a cooling-only system needs planning permission.
What are the limits in England?
These come from Class G as amended on 29 May 2025. If any one of them fails, the install needs a planning application.
| Limit | Rule |
|---|---|
| Number of units | One on a non-detached house or a block of flats; two on a detached house |
| Size of outdoor unit | Up to 1.5 m³ including housing on a house; 0.6 m³ on a block of flats |
| Noise | Must meet MCS 020a; from 28 May 2026 the "or equivalent" route ended |
| Roof | Not on a pitched roof; on a flat roof, at least 1 m from the edge |
| Listed buildings and scheduled monuments | Not permitted |
| Conservation areas and World Heritage Sites | Not on a wall or roof fronting a highway, or nearer a highway than the house |
| Elsewhere | Not on a wall fronting a highway above ground-floor level |
| Wind turbines | Not if there's already a wind turbine on the building or in the garden |
The old rule that a unit had to be at least 1 metre from the property boundary was removed in 2025. Article 4 directions or planning conditions on a house can still take away permitted development rights, so check with the council if the house is on a new estate or in a sensitive area.
Run this on the survey
Ask these in order while you're on site. Most domestic jobs clear it in a minute.
No application needed in England. Keep the MCS 020a calculation with the job file. If the customer wants certainty, they can apply for a lawful development certificate.
A cooling-only unit isn't covered. Offer a heat pump that heats and cools, or tell the customer to apply.
Permitted development doesn't apply. The customer needs consent before anything is fixed to the building.
Move the unit, pick a smaller or quieter one, or tell the customer an application is needed before you book the install.
Class G covers houses and blocks of flats. Shops, offices and restaurants usually need planning permission for external units; councils often ask for a noise assessment.
What about shops, offices and restaurants?
Usually you need permission. Class G only covers houses and blocks of flats. Councils typically treat external air conditioning plant on commercial buildings as needing planning permission: one London borough's business guidance says permission is needed to install, alter, replace or move air conditioning where any part is fixed to the outside, and that noisy plant applications need a noise and vibration assessment. Check the local council's guidance before you quote a commercial job, and build the application time into the programme.
Is it different in Wales, Scotland and Northern Ireland?
Yes, so check where the job is before giving the customer an answer.
| Wales | Scotland | Northern Ireland | |
|---|---|---|---|
| Can heat and cool? | Yes, from 1 June 2026; not cooling-only | Must be used only for heating or hot water | Must provide heat |
| Number | Two on detached, one otherwise | One | One |
| Size | Up to 1.5 m³ | No volume limit; up to 1 m from a wall or roof | External unit up to 3 m high |
| Noise standard | MCS 020a | MCS or equivalent | Not stated in the order |
| Boundary | No fixed distance | No fixed distance | Not within 1 m of a neighbouring house's boundary |
| Conservation areas | Not on a road-facing wall or roof | Ground floor, rear only | Not facing and visible from a road |
From the Welsh Government heat pump planning page, Scottish Government Circular 1/2024 and the Planning (General Permitted Development) (Amendment) Order (Northern Ireland) 2023.
In Scotland, the right is for domestic heating, so a reverse-cycle unit installed mainly for cooling sits outside it. Ask the planning authority if in doubt.
Who should check, you or the customer?
Planning permission is the property owner's responsibility, but they'll ask you. Answering it on the survey, in writing, saves a lost job later.
Customers want accepting a quote to be simple, and planning is one of the questions they raise before they'll say yes. Put a line on the quote: "Installed as permitted development under Class G; assumes the property isn't listed, in a conservation area or subject to an Article 4 direction." It sets expectations and flags the cases where the customer needs to check.
You'll also need F-gas certification to fit the refrigerant side; see F-gas certification for air conditioning installers. For a site-specific RAMS for the install, see working from a master RAMS template. If the customer is a landlord, a heating-and-cooling heat pump may also help with EPC upgrades.
Where Nexley fits
Nexley is the AI back office for UK trade firms: five AI assistants run your tenders, quotes, buying, scheduling and invoicing. It connects to the tools you already work in, you run it all from WhatsApp, and you approve everything. £799 a month.
Nexley runs the survey questions for you. Send the address and a photo of where the outdoor unit will go on WhatsApp, and it drafts the quote with the planning line, the MCS 020a noise check details to fill in, and the RAMS, for you to check and approve. If the house is in a conservation area or listed, it flags it before the quote goes out.
Common questions
Do I need planning permission for air conditioning on my house?
In England, usually not, if it's a heat pump that heats as well as cools, the outdoor unit is 1.5 m³ or less, it meets MCS 020a and it isn't on a pitched roof, a listed building or a road-facing wall in a conservation area. Cooling-only units need permission.
Do I need planning permission for air conditioning on a flat?
A block of flats can have one heat pump under permitted development, with an outdoor unit up to 0.6 m³. Leaseholders will usually also need the freeholder's permission, which is a separate question from planning.
Has the 1 metre boundary rule for heat pumps gone?
Yes, in England. The amendment in force from 29 May 2025 removed the requirement for the unit to be at least 1 metre from the property boundary. Northern Ireland still has a 1 metre rule from a neighbouring house's boundary.
Does air conditioning on a shop need planning permission?
Usually. Permitted development under Class G covers houses and blocks of flats only. Check with the local council, which may ask for a noise assessment.
Sources
- legislation.gov.uk: GPDO 2015, Schedule 2, Part 14, Class G
- legislation.gov.uk: GPDO (England) (Amendment) Order 2025, SI 2025/560
- legislation.gov.uk: Impact assessment, amendments to the air source heat pump permitted development right
- Planning Portal: Planning permission for air source heat pumps
- Planning Portal: Do I need planning permission to add air conditioning to my home?
- Welsh Government: Planning permission, domestic heat pumps
- Scottish Government: Circular 1/2024, householder permitted development rights
- legislation.gov.uk: Planning (General Permitted Development) (Amendment) Order (Northern Ireland) 2023
- Lewisham Council: Planning FAQs for businesses
Every rule, rate and date above was checked against these sources on the date shown at the top.
Keep reading
Safety, certificates and compliance
Site-specific RAMS without two hours a job: working from a master template
Most of a RAMS is the same every time you do the same task. This guide shows how to split it into a master you write once and a one-page site sheet you fill in per job, with the master headings ready to copy.
Safety, certificates and compliance
Construction phase plan for small jobs, with a template
Under CDM 2015, the builder writes the construction phase plan on most small jobs, before work starts. This guide gives a fill-in template based on HSE's own, a worked example for a kitchen extension, and a quick check on notification.
Safety, certificates and compliance
F-gas certification for air conditioning installers
Installing split air conditioning means working on a refrigerant circuit, and that needs two certificates: one for the engineer and one for the business. This guide has a quick check for which you need, Refcom's fees worked out per year, and what electricians can and can't do.
