Air conditioning installation in London

Roughly half of London's homes are flats, and that shapes home air conditioning installation in London more than any refrigerant rule or heatwave. The hardware is the same as anywhere else. Prices are too, though parking, access and congestion charging tend to push London quotes towards the top of the ranges in our cost guide. The order of work is what differs. In most of the south east, the first question is which wall the outdoor unit should go on. In London, it is who owns the wall.

A freehold house in Walthamstow or Ealing is much like a project anywhere else. If you own a leasehold flat, whether in a Victorian conversion in Clapham, a mansion block in Maida Vale or a new-build tower in Nine Elms, the freeholder conversation comes before the survey, before the quotes, and long before anyone drills a wall.

Find your part of London

The rules below apply across the capital. The housing does not, so we have written separate guides where the local picture changes the job:

• South London: terraces with no side access, where pipework has to cross the house to reach a condenser at the back; converted flats; and ex-council blocks where the council is both landlord and planning authority.
• West London: Hammersmith, Fulham, Chiswick and Ealing, where noise between closely packed back additions, mansion-block lightwells and riverside apartments set the terms.

On the outer edge, the guides for Surrey, Kent, Essex and Hertfordshire cover larger houses with more room for an outdoor unit.

If your question is about the property rather than the postcode, start with the guide that matches it:

• Flats: freeholder consent, planning and the order to do things in.
• Period homes: routing pipework through Victorian and Edwardian houses without spoiling them.
• New builds: airtight homes that overheat upstairs, and estates where permitted development rights have been removed.
• Loft conversions: the hottest rooms in the house.

Larger houses cooling three or four bedrooms usually suit a multi-split, and a full renovation is the moment to price a ducted system. Top-floor and west-facing rooms need the most capacity; the sizing guide explains the calculation.

Freeholder and managing agent consent comes first

In a leasehold flat, the external walls, the roof and usually the structure of any balcony belong to the freeholder. Fixing a condenser to any of them without permission is normally a breach of the lease, however small and quiet the unit. The consent you need is written: a licence for alterations or a formal letter from the freeholder or managing agent, and in a share-of-freehold conversion, the agreement of the other owners. A verbal yes from a porter or a neighbour is worth nothing when the block changes managing agent three years later.

How long this takes is the least predictable part of any London installation. A responsive agent for a two-flat conversion might turn consent round in a fortnight. A large purpose-built estate can take months, and many new-build towers refuse as a matter of policy, because the facade is a single engineered, warrantied system and nobody may bolt anything to it. Where cladding remediation or building-insurance questions are live, expect extra caution.

Get consent moving before you commission a survey, because quotes typically hold for 30 to 60 days and freeholder decisions often take longer. A balcony is not a loophole: even where the lease gives you the balcony, fixing a unit to its structure usually still needs consent. Budget for the freeholder's legal and surveyor fees too; several hundred pounds is common. If the answer is a firm no, systems without a conventional outdoor unit solve some London flats, with honest compromises on noise and efficiency.

Planning: flats, cooling-only units and conservation areas

London has 32 boroughs plus the City of London, each its own planning authority with its own conservation areas, Article 4 directions and appetite for enforcement. The same condenser on the same style of wall can be uncontroversial in one borough and a breach across the boundary.

On a house, an outdoor unit can fall within permitted development under Class G of Part 14, subject to conditions on size and siting and to the MCS 020(a) sound assessment, which must show no more than 42 dB(A) at the neighbour's assessment position [1][2]. Three things catch Londoners out.

Flats. Class G can apply to a block of flats, but only as one installation for the whole block, not one per flat. A leaseholder fitting their own condenser should expect to apply to the borough for planning permission, on top of freeholder consent rather than instead of it [2][3]. The 42 dB(A) test is a permitted development condition; for a flat, noise is weighed on the planning application and often written into the freeholder's consent.

Cooling-only equipment. One of the Class G conditions is that the unit is not used solely for cooling [2]. A reversible split, which heats as well as cools, qualifies; a cooling-only unit fitted outside generally needs permission even on a house. Nearly every split quoted today is reversible, and you are not obliged to use the heating, but check the quote says so.

Conservation areas, which inner London designates widely. Lambeth has 62 covering about 30% of the borough [4]. Hammersmith & Fulham has 44 covering about half of it [5]. In Kensington and Chelsea they cover around 70% [6]. Inside one, the unit cannot go on a wall or roof fronting a highway, or sit nearer the road than the house [2]. Listed buildings need listed building consent regardless of permitted development, and an Article 4 direction can remove rights street by street, so a neighbour's condenser tells you nothing about yours. Check your address on the borough's own map.

The Party Wall etc. Act 1996 comes up less often than people fear. Most installations go through your own external wall. It becomes relevant if the plan involves cutting into a party wall, for example coring a pipe route through the wall you share with next door, or fixing the condenser to a masonry garden wall that straddles the boundary [7]. If an installer proposes either, ask whether a notice is needed before work starts.

Settle the unit position with the borough's rules in view before any pipework is priced. The planning permission guide walks through the full Class G checklist, and our guide to choosing an installer covers F-gas certification and what to ask for in writing.

Next step

Request an installer match. We'll review your requirements and match you with a suitable installer operating in your area. If you live in a flat, have your managing agent's details and the lease's alterations clause to hand; in London that paperwork sets the timetable more than the engineering does.