Planning permission for air conditioning
Most domestic air conditioning in England can be installed without planning permission, under “permitted development” rights — but with one crucial catch: those rights apply to systems that provide heating as well as cooling, and specifically exclude equipment used solely for cooling. Flats, listed buildings, conservation areas and commercial premises have stricter rules.
Please check before you install
Planning rules change and vary by location. This is a guide to the position in England; Scotland, Wales and Northern Ireland differ, and local restrictions (such as Article 4 directions) can apply. Always confirm with your local planning authority. (Verified June 2026 against the Planning Portal — re-check current rules.)
The key point: heating-and-cooling vs cooling-only
In England, the permitted development right that covers outdoor units is the one for air source heat pumps. A reverse-cycle air conditioner — one that heats as well as cools — can fall under it. But the rules specifically exclude equipment used solely for cooling, so a cooling-only unit isn’t covered and will normally need planning permission. Since most modern systems heat and cool, this works in most homeowners’ favour — but it’s the first thing to check.
Permitted development conditions (houses, England)
For a reverse-cycle system on a house, the main conditions to qualify as permitted development include:
- The outdoor unit (including its housing) is no larger than 1.5 cubic metres (increased from 0.6 m³ in May 2025).
- It’s not on a pitched roof, and if on a flat roof, every part is at least 1 metre from the edge.
- The installation meets the MCS Planning Standards (MCS 020) noise requirements (or an equivalent standard until 28 May 2026, after which MCS 020 is the only accepted scheme).
- There’s no wind turbine on the property.
- Only the first heat pump counts as permitted development on a non-detached house (the first two on a detached house).
- The unit is not used solely for cooling, is removed when no longer needed, and is sited to minimise its visual and noise impact.
The old rule requiring the unit to be at least 1 metre from the boundary was removed for houses in England in May 2025.
Flats, listed buildings and conservation areas
- Flats: the size limit is smaller — 0.6 cubic metres — and you’ll typically also need your freeholder’s or management company’s consent under the terms of your lease.
- Listed buildings: you need Listed Building Consent regardless of where the unit goes, and installing without it is a criminal offence — always check a building’s listed status first.
- Conservation areas and World Heritage Sites: the unit must not be fitted on a wall or roof that faces a highway (or nearer a bounding highway than the building), so siting needs more thought and prior approval may be required.
- Article 4 directions: in some areas councils have removed permitted development rights, so an application is needed even for an otherwise-qualifying system.
Commercial premises, and the rest of the UK
- Commercial buildings: the heat-pump permitted development right is a domestic one, so commercial air conditioning generally requires planning permission — larger systems and their visual and noise impact make this the norm.
- Wales: still requires the outdoor unit to be a set distance (around 3 metres) from the boundary, which makes permitted development harder than in England.
- Scotland: has its own permitted development rules, broadly similar to England’s post-2025 position but with local variations.
- Northern Ireland: has its own planning regime — check locally.
Noise and neighbours: even where planning permission isn’t needed, noise is the most common cause of disputes. The MCS 020 noise calculation is designed to keep an outdoor unit within a set limit at a neighbour’s property, and siting it thoughtfully — away from boundaries, windows and quiet rooms — is the best way to avoid problems. See noise levels explained.
Know exactly what to ask for
Build a free, impartial plan for your space — the right system, the size each room needs, and what good kit looks like. We don't sell or fit units.