Air conditioning in flats: who has to say yes in the UK

Yes, you can fit air conditioning in a flat. "Air conditioning units are not banned," a government spokesperson said in June 2026. What makes air conditioning in flats harder than in a house is that three parties can say no: the freeholder under your lease, the council under planning rules, and your neighbours through noise. In England, a block of flats can use the permitted development right for one reversible unit of no more than 0.6 cubic metres, but a cooling-only unit cannot. Read the lease first, check planning second, then pick the system.

Last checked 10 October 2026 against the primary sources listed at the end. Planning rules are for England. This is general information, not legal advice.

1. Read your lease for the alterations covenant and who owns what.
2. Check planning for your flat (in England, Class G).
3. Pick a system that needs the fewest permissions.
4. Test the noise against the 37 dB rule.
5. Price the job, including what a flat adds.
6. Check the installer's F gas certification before paying.

Who can say no to air conditioning in a flat?

The freeholder controls the building through your lease, the council controls the outside through planning, and neighbours can complain about noise. Take them in that order, because the lease can stop everything else and is the cheapest to read. Dee Aylward, a partner at Mishcon de Reya, wrote in July 2026: "The key message is simple: do not instruct a contractor before taking advice."

Step 1: Read your lease

What you own, and what you do not

Your lease grants a "demise", the part you hold. Mishcon says it will usually exclude the structure of the building, which covers the external walls where a refrigerant pipe and outdoor unit tend to go.

Absolute or qualified covenant

Look for the clause on alterations. Mishcon says most residential leases restrict them, that depending on the wording the landlord may be under no obligation to consent at all, and that some leases or building rules may prohibit air conditioning altogether.

A qualified covenant lets you make alterations with consent. Section 19(2) of the Landlord and Tenant Act 1927 says that where a lease bars improvements without consent, consent is "not to be unreasonably withheld", and the landlord can ask for a reasonable sum for damage and for legal expenses properly incurred. It does not rescue an absolute covenant.

When every lease in the block says the same

In Duval v 11-13 Randolph Crescent [2020] UKSC 18, about a block of nine flats in Maida Vale, the Supreme Court held that a landlord could not license works breaching an absolute covenant where the other leases let any lessee require the landlord to enforce it. So a willing freeholder can be unable to say yes. The case construed those leases; it is not a general rule.

What to put in the request

Send the unit make and model, the outdoor unit position with a photograph or drawing, the pipe route and drilling point, the noise data, the installer's F gas certificate, and an offer to make good any damage.

Costs and time

Mishcon says consent can take time and usually involves paying the landlord's legal and surveyor's costs. We found no reliable published fee, so ask the managing agent in writing. If a refusal looks unreasonable, take advice from a solicitor or LEASE.

Step 2: Check planning for your flat

Flats are not excluded from the heat pump rule

A common line is that flats have no permitted development rights. That is true for extensions, because Article 2 of the 2015 Order says "dwellinghouse" does not include a building containing flats. But Class G, the right for air source heat pumps, covers "a dwellinghouse or a block of flats". The legislation.gov.uk text is up to date to 7 October 2026.

The Planning Portal adds one test: "A block of flats must consist wholly of flats (e.g. should not also contain commercial premises)." Rights can also be removed by a planning condition or an Article 4 direction.

Does your unit qualify?

England, Schedule 2, Part 14, Class G, read 10 October 2026.

The cooling-only trap

Condition G.3(aa), inserted on 29 May 2025, requires that "the air source heat pump is not solely used for the purpose of cooling". The Planning Portal's air conditioning FAQ is blunt: if the system only cools, the rights do not apply and a planning application is required. A reversible model of a similar size can fall within Class G if it meets every other limit.

Grey areas and how to settle them

"Block of flats" is not defined in Article 2, so a converted house or a block with a shop below may not fit. Brighton and Hove council says a certificate of lawful development is the formal confirmation that works are permitted development. Mishcon says air conditioning with pipework and an external condenser will very often trigger listed building consent.

Fees

From 1 April 2026 the fee for alterations to a single dwellinghouse in England is £548, but a flat is not a "dwellinghouse" under Article 2 and the fee table does not say where a flat's condenser falls. Ask your council.

Wales, Scotland and Northern Ireland

Wales updated its rules on 1 June 2026 and excludes cooling-only units, but its guidance page does not mention flats. Scotland's Class 6H covers buildings containing flats. We could not verify Northern Ireland's position for flats. Check with your council.

Step 3: Pick a system that fits the permissions

The less you drill and the less you put outside, the fewer people can say no.

Where there is no agreed place for an outdoor unit, a portable may be the only route that needs no consent. Our split system guide and guide to choosing air conditioning for your home cover the trade-offs.

Size it before you ask for consent

Daikin UK's rule of thumb is about 0.1 kW per square metre, so 20 m2 is about 2 kW. It says the South East can need about 20% more than Scotland, and a poorly insulated, sun-facing room needs more, which in a block often means the top floor.

Where the outdoor unit goes

Daikin's Perfera specification allows 10 m of pipe with no extra refrigerant, then 0.02 kg per metre, up to 20 or 30 m depending on model. On a seafront balcony, note that Toshiba's warranty guidelines say high levels of nitrogen oxides and sulphur dioxide commonly occur within 3 miles of the coast, so ask about coil protection.

Step 4: Noise and your neighbours

The 37 dB test and who counts as a neighbour

Class G depends on the MCS 020 a) noise calculation. The limit is 37 dB LAeq,5mins, measured 1 m outside the centre of any door or window to a habitable room of a neighbouring property. For flats, the standard says: "In instances where the heat pump would be installed on a block of flats, neighbouring property includes flats within the same block of flats". Your own flat is excluded. Passing the test does not on its own give you permitted development rights.

Why the number on the box is not the number at the window

Daikin lists Perfera outdoor units at 46 to 49 dBA sound pressure, nominal. That is a figure for the unit itself. The 37 dB limit applies at a neighbour's window, so distance, walls and position change the result. Ask the installer for the MCS 020 a) calculation for your exact position.

If a neighbour complains anyway

Section 79(1)(g) of the Environmental Protection Act 1990 makes noise from premises that is prejudicial to health or a nuisance a statutory nuisance, and councils must inspect their area for nuisances. Being permitted development does not stop a nuisance complaint.

Step 5: What it costs in a flat

Install cost ranges

Our air conditioning cost guide explains how we set a headline of £1,800 to £3,500. Four Sussex installers advertise single splits from £1,000 to £2,500 (read 10 October 2026). Those are advertised prices, not quotes.

What changes the price in a flat

Heatable gives about £800 to £1,200 per extra indoor unit and £200 to £1,000 for electrical work. Trade2Base puts a two-room system at £3,200 to £5,500. A flat can add access equipment, a longer pipe run and the landlord's fees from Step 1. We found no published price for those.

Running costs

Ofgem's cap for 1 October to 31 December 2026 is 26.32p per kWh. At that rate a 3.5 kW split costs about 10p an hour at SEER 9.25 and about 15p at SEER 6.1. Over the label's 350 cooling hours a year that is roughly £35 to £53. Our running costs guide shows the sum.

The £2,500 Boiler Upgrade Scheme grant

Ofgem lists £2,500 off air-to-air heat pumps for residential properties only, in a scheme open in England and Wales. The 2026 regulations say the unit must replace the heat generating components of the original heating system, where applicable. On 10 October 2026 MCS said no installers were yet certified for air-to-air heat pumps, so for now the grant exists on paper. Read our air-to-air heat pump guide before paying for anything on the strength of it.

Step 6: Check the installer before you pay

F gas certification, company and person

GOV.UK says a company must be certified to install, repair or maintain air conditioning containing F gas, by a body such as Refcom, the F-Gas Register (Quidos) or Bureau Veritas UK, renewed every 3 years. Each engineer also needs personal qualifications. Ask for both, and use our F gas register check guide. A register miss is not proof of no certificate, because listing is optional.

What a survey in a flat should cover

Free surveys are common. A survey should measure the rooms, assess insulation and window orientation, and settle the outdoor unit position and pipe route. None of the 39 installers listed on our site states flat or leasehold experience, so ask directly.

If you rent your flat

A fan or blinds need no drilling. A portable with a window hose may be allowed, but the tenancy agreement decides. To ask:

1. Read the tenancy agreement for alterations and fixings.
2. Ask the landlord in writing, naming the unit and where it goes.
3. Offer to make good any marks when you leave.
4. Get consent in writing before buying anything.

We found no right for a tenant to fit air conditioning. The first phase of the Renters' Rights Act 2025 began on 1 May 2026 in England, but we found nothing in it on alterations, so the tenancy and the landlord's written consent decide it.

Brighton and Hove: a city of flats

The council's 2021 Census briefing says 50% of Brighton and Hove households (60,754 of 121,401) live in a flat, against 22% in the South East and England. 19.6% live in part of a converted or shared house, against 3.1% in the South East. Converted houses are the Class G grey area from Step 2, and the council says planning controls are tighter in conservation areas. See the Brighton and Hove installer directory for what we found on each firm's F gas status.

Checklist before you book anything

Do not pay a deposit until each line has an answer in writing.

• Lease covenant type noted (absolute or qualified).
• Written consent from the freeholder or landlord.
• Planning route settled: Class G, or a certificate of lawful development.
• Reversible unit, not cooling-only.
• Outdoor unit no more than 0.6 cubic metres including housing, one per block.
• MCS 020 a) noise figure for your position.
• Three itemised quotes for the same specification.
• F gas company certificate and engineer qualification.
• Written warranty and servicing terms.

Start with the first line: email the managing agent and ask for their consent procedure and fees in writing.

our Brighton and Hove installer directory