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Air conditioning in a leasehold flat or listed building
Air conditioning in a leasehold flat needs two separate yeses: the lease's, and planning's, which in England allows just one 0.6 m³ outdoor unit for the whole block.
By the Cooler Indoors desk · figures checked · 3 charts · sources · methods
Fitting air conditioning in a leasehold flat means clearing two separate hurdles: what your lease allows, and what planning law allows for the building. Listed homes add a third, because the alteration itself can need consent. Houses get more room under the planning rules than flats do.
Source: legislation.gov.uk, GPDO (England) Amendment Order 2025 · checked 29 October 2026
How we read this Maximum outdoor unit volume, including any housing, without a planning application. The Welsh figure comes from SI 2026/79 (from 1 June 2026). Scotland and Northern Ireland do not use a volume cap.
Show the numbers
| Label | m³ | Note |
|---|---|---|
| Flat block, England | 0.6 | Tightest limit |
| Flat block, Wales | 1.0 | |
| House, England or Wales | 1.5 |
Can you install air conditioning in a leasehold flat?
Only if the lease allows it, and often only with the landlord's agreement. GOV.UK explains that your lease sets out the conditions you agreed to, including whether you need permission to make alterations. Breaking those conditions can lead to court, an order to pay for damage, and in serious cases loss of the lease.
GOV.UK notes that most flats are leasehold, and an outdoor unit, a hole through an outside wall and pipework down the building all touch parts you may not own. Check your lease and ask the freeholder or managing agent in writing before work starts. Keep their reply with the installer's paperwork.
What does permitted development allow on a block of flats?
One air source heat pump for the entire block, and in England its outdoor unit may not exceed 0.6 m³. Those limits come from the 2025 amending order, which also confirmed that a unit used only for cooling is outside the rights. Read plainly, the first flat to fit a unit under these rights may use the block's only allowance.
Source: legislation.gov.uk, GPDO (NI) Class G as substituted by SR 2023/95 · checked 29 October 2026
How we read this Outdoor units allowed without an application for a building of flats. Northern Ireland's rights apply to a dwellinghouse, so a flat there needs a planning application. A second unit, or a bigger one, needs permission everywhere.
Show the numbers
| Label | units | Note |
|---|---|---|
| England block | 1 | |
| Wales block | 1 | |
| Scotland building | 1 | |
| N. Ireland block | 0 | Rights cover houses only |
The full nation-by-nation conditions for houses, including the noise calculation, are on our planning rules page for each UK nation.
Do listed buildings need consent for air conditioning?
Yes, in practice. Under section 7 of the Listed Buildings Act 1990, works that alter a listed building in a way that affects its character need listed building consent. Permitted development for heat pumps excludes listed homes in England, Wales and Scotland, and Northern Ireland requires consent first. The Planning Portal also states that a listed home needs consent for air conditioning.
That applies to the whole curtilage in England, so a unit in the garden of a listed house is still caught. Talk to the council's conservation officer before choosing a model.
What changes in a conservation area?
Siting tightens. In England, a unit may not go on a wall or roof that fronts a highway, or nearer the road than the house. Scotland's householder guidance, Circular 1/2024, restricts a conservation-area unit to the ground floor and rear elevation. Flats in these areas can face both the lease question and a planning application.
Source: gov.scot, Circular 1/2024 householder permitted development, chapter 6 · checked 29 October 2026
How we read this Distances from each nation's permitted development rules (England GPDO G.2(g); NI SR 2023/95). England has no boundary gap since May 2025. These apply to houses; flats usually need permission anyway.
Show the numbers
| Label | m | Note |
|---|---|---|
| England: gap from a flat-roof edge | 1 | |
| Scotland: most a unit may protrude | 1 | |
| N. Ireland: gap from a neighbour's boundary | 1 | |
| Scotland: freestanding height cap | 3 | |
| N. Ireland: outdoor unit height cap | 3 |
| Your situation | Ask | Why |
|---|---|---|
| Leasehold flat | Freeholder or managing agent, in writing | The lease sets whether alterations need permission |
| Any flat in England | Council planning team | One 0.6 m³ unit for the whole block under permitted development |
| Listed home | Council conservation officer | Listed building consent; permitted development excluded |
| Conservation area | Council planning team | No unit on a wall or roof fronting a highway |
| Renting | Landlord, in writing | Fixing a unit alters the landlord's property |
Where does the water go when there is no drain nearby?
An indoor unit collects water as it cools, and it has to run somewhere. In a flat with no drain at the right height below the indoor unit, installers fit a small condensate pump to lift it out. Choosing and placing it is part of the F-gas engineer's and electrician's job; who does which part is set out separately.
What if you rent and the flat overheats?
Ask your landlord in writing before anything is fixed to the building. If the home is dangerously hot, the NHS heatwave advice points tenants to the council: its environmental health officers can look at excess heat as a hazard in rented homes.
Questions this data raises
Can my neighbour's unit stop me fitting one on the same block?
Under England's rules a block of flats gets one outdoor unit under permitted development. If one is already there, a second would normally need a planning application, so ask the council.
Does a unit on a balcony avoid the lease question?
No. Balconies, outside walls and the routes for pipework can be covered by the lease, so the same written request to the freeholder or managing agent applies.
Is a portable air conditioner allowed in a listed flat?
A portable unit is not fixed in place, so the heat pump planning rights do not cover it either way. Venting it through a window can still raise lease or listed building questions, so check with the freeholder and the council.
Do I need consent for a unit in the garden of a listed house?
In England, yes in practice: permitted development excludes the whole curtilage of a listed building, so speak to the conservation officer first.
Sources for this page
- legislation.gov.uk, GPDO (England) Amendment Order 2025 legislation.gov.uk
- whether you need permission to make alterations gov.uk
- leasehold gov.uk
- legislation.gov.uk, GPDO (NI) Class G as substituted by SR 2023/95 legislation.gov.uk
- section 7 of the Listed Buildings Act 1990 legislation.gov.uk
- gov.scot, Circular 1/2024 householder permitted development, chapter 6 gov.scot
- NHS heatwave advice nhs.uk
All checked 29 October 2026. How we choose and read sources: Methods & sources.