Often not, if the unit also works as a heat pump. In England, permitted development covers many air source heat pumps on homes, within set size and siting limits. It does not cover a unit used solely for cooling. A conservation area, a listed building or an Article 4 direction can remove those rights, so check locally before booking work.
Why the planning question comes up at all
Most homeowners treat a wall-mounted air conditioning unit as a small add-on. Often, that is a fair view. However, an outdoor unit still changes the outside of a building. As a result, it falls under England’s planning rules like other outside work.
Permitted development rights decide most of these cases. GOV.UK describes them as a national grant of planning permission for certain works. The key question is whether your unit counts as a heat pump in planning terms.
This guide covers the rules in England only. Scotland, Wales and Northern Ireland each run their own planning system. Since each has its own rules, the detail below may not carry across the border.
What permitted development actually allows
The General Permitted Development Order grants automatic rights for smaller works. For example, Part 14, Class G covers air source heat pumps on homes. It applies to houses and to blocks of flats alike.
However, a unit must still meet set limits. The outdoor unit on a house cannot exceed 1.5 cubic metres. On a block of flats, the limit is 0.6 cubic metres.
Numbers are capped as well. A detached house can have up to two heat pumps, while other homes and blocks of flats can have one. A unit also cannot sit on a pitched roof.
In addition, the owner must site it to limit its effect on the look of the building and the area. They must also remove it once it is no longer needed.
These limits changed on 29 May 2025. The old rule keeping a unit at least one metre from the boundary was removed. The size limit for houses also rose from 0.6 to 1.5 cubic metres. These are the same limits that apply to air conditioning installation in Chippenham, whatever the age or style of the property.
Cooling-only units versus reversible systems
The real test comes down to what a unit does, not what the trade calls it. Since May 2025, Class G has carried a clear condition. The heat pump must not be used solely for cooling.
A reversible unit heats a room in winter as well as cooling it in summer. Because of that, it can fall within Class G, provided it meets the size and siting limits. A cooling-only unit, in contrast, cannot use Class G at all.
This point matters once you see the system your installer proposes to fit. The choice between a heat-and-cool system and a cool-only one can decide whether you need to apply. Therefore, raise it with the installer directly before you agree a quote. It’s a question worth raising early for air conditioning installation in Yeovil too, since the same reversible-versus-cooling-only test applies everywhere in England.
Conservation areas, listed buildings and Article 4 directions
Permitted development rights do not apply the same way everywhere. Three cases come up often for air conditioning.
A conservation area or World Heritage Site adds a siting rule. There, Class G does not allow a unit on a wall or roof that fronts a highway. Bath, for instance, has been a World Heritage Site since 1987, which matters for any home cooling install in Bath. Where the home is a flat, the lease adds another consent step, and air conditioning in a flat walks through it.
Class G does not apply to a listed building, so an outdoor unit there needs a planning application. Listed building consent is also a separate regime. It may be needed alongside planning permission, not in place of it.
An Article 4 direction lets a council or the Secretary of State withdraw permitted development rights across a set area. The work then needs a planning application instead. None of these three shows from the street, so check with the local council first.
What this means for a commercial installation
Commercial sites follow a different path from homes. Class G covers domestic premises only. Part 14 has no matching class for air source heat pumps on business premises.
Because of that, a shop, office or restaurant should expect to need planning permission more often than a house would. Listed status and conservation rules apply to commercial buildings too. Anyone planning a commercial air conditioning job should build a planning check into the timeline early.
Checking before you commit
The planning answer depends on the exact property, not just the type of unit. Because of that, the best first step is always the local planning authority’s own guidance. Many councils also offer pre-application advice.
A short check, made before any work is booked, is usually enough. Although the rules above cover most cases, only the council can confirm the position for your address.
Recent planning decisions nearby can also help. Seeing whether a neighbour’s outdoor unit needed a full application is a useful early signal. Still, it is not a guarantee your own property will be treated the same way.
An installer who works in your area can talk through the likely position at survey. That does not replace a formal check with the council. However, it does mean fewer surprises once you agree a quote.
If you are ready to move ahead, our air conditioning installation service covers homes across South West England. That includes air conditioning installation in Salisbury and the area around it.
One enquiry puts you in touch with one pre-qualified installer for this job. It is free, with no obligation.
Submit one enquiry through our contact page. Your installer can then flag any planning points that apply to your property — get in touch.
