For years, domestic air conditioning in Britain has been treated as faintly vulgar.
It was for hotels, offices, Dubai apartments and Americans on television who have “central air”. Proper British people did not have air conditioning. Proper British people opened a window, bought a fan from Argos, complained about the fan, slept badly, and then told everyone about it.
That worked when summer was a brief national inconvenience involving warm lager, sunburn and one regrettable barbecue.
It works rather less well when the bedroom is still hot at midnight, the baby will not sleep, and the top floor is behaving like a slow cooker.
So here we are. Britain, the country that spent decades improving its homes so they would keep heat in, is now surprised to discover that they keep heat in.
This is not just a comfort issue anymore. It is becoming a property issue, a planning issue, a leasehold issue, a neighbour issue and, eventually, a conveyancing issue. The old winter logic is running into the new summer reality, and somewhere in the middle is a small white box humming on a bracket.
That box is where the trouble starts.
The problem with British homes
British residential property has been built, regulated and sold through a winter lens. We have cared about insulation, glazing and EPC ratings. We have talked endlessly about keeping warm, reducing heating bills and stopping heat escaping through the roof.
None of that was wrong. In fact, much of it was necessary. But a home that holds heat very well in January will also hold heat very well in July, which is less charming when the main bedroom feels like the inside of a Breville toastie.
This is the awkward bit the property market has been slow to admit. A house can be efficient and unpleasant. A flat can have a respectable EPC and still be unbearable in a heatwave. A new-build apartment can look clean, modern and clever in the sales brochure, then turn into a glass-fronted reptile house by bedtime.
We need to start talking about overheating as part of habitability, value and risk. Not as a lifestyle complaint. Not as a moan from people who cannot cope with summer. Not as something that can be solved by pointing a plastic fan at a bowl of ice and pretending we are all in the Blitz.
The climate has moved on.
The law has at least started to recognise overheating, although mostly through the new-build door. Approved Document O now deals with overheating in new residential buildings, which is important, but it does not solve the existing stock problem: the Victorian conversion, the 1930s mansion block, the loft room, the sealed-up new-ish flat, and the south-facing bedroom that has declared independence from sleep.
What people mean by “air con”
Part of the difficulty is that people use “air conditioning” to mean several different things.
There is the portable unit: the loud indoor box with a hose out of the window, bought in a panic and moved from room to room like a disappointing domestic pet. It is ugly, and usually inefficient, but it is not normally the main legal problem.
The real fun begins with a proper split system.
That usually means an internal unit, an external condenser and pipework between the two. In normal human language: something on the wall inside, something on the wall outside, and a hole through the building so they can talk to each other. There may also be electrical work, refrigerant pipework, condensate drainage, fixings, maintenance obligations and a future argument with someone who lives underneath.
This is not a fan with ambition; it is plant.
Domestic plant, yes. Small plant, perhaps. Sensible plant, quite possibly. But once it attaches to the outside of the building, or once it needs pipework through the fabric, it stops being merely an appliance and becomes part of the legal story of the property.
Houses are not immune
It would be tempting to say this is all a leasehold flat problem. It is not.
A freehold house gives an owner far more room to manoeuvre, but it is not a kingdom with a condenser. External units can still create planning issues, noise issues and neighbour issues. They can be a problem in conservation areas, a serious problem on listed buildings, and an avoidable eyesore if bolted to the wrong elevation with the aesthetic sensitivity of a kebab shop extractor fan.
There may be restrictive covenants. There may be estate controls. There may be planning conditions from the original development. There may be a neighbour who has already decided that your air conditioning unit is the beginning of social collapse.
Leasehold houses can be more awkward again, because they often look and feel like ordinary home ownership while still carrying landlord consent requirements or estate management restrictions in the title.
So no, houses are not as complicated as flats. But the moment the unit goes outside, the law may follow it.
Flats are where the Hound starts growling
Flats, however, are the true battlefield. And no “common hold” will not fix this!
Most leaseholders do not own the building. They lease a defined space within it, and the lease decides what that space includes. Very often the external walls, roof, structure, service risers, common parts and sometimes even balcony structures are not truly theirs to alter.
That matters because a split air conditioning system needs somewhere for the external unit to go. If it is fixed to an external wall, that wall may belong to the landlord. If it sits on a balcony, the leaseholder may not be entitled to use the balcony for a plant. If it goes on the roof, the roof is almost certainly not theirs. If pipework passes through common parts, the leaseholder is not making a private domestic choice; they are interfering with the building.
This is why “the installer said it was fine” has all the legal force of a horoscope. The installer may know the machine, the do not know the building.
Planning: the cooling-only trap
Planning is where many people will get caught, mainly because the public discussion is already drifting towards two bad answers: “air conditioning is banned” and “air conditioning is permitted development”.
As ever, the truth is more annoying.
Some systems may fall within permitted development rights, particularly where they are air-source heat pump systems capable of heating as well as cooling. Cooling-only systems are more dangerous territory. If the unit only cools, planning permission may be required. The Planning Portal puts the trap neatly: the permitted development rights “only apply if the system provides a heating function”, and if the system “only offers a cooling function”, the rights do not apply and planning permission is required. That is a rather important distinction for anyone merrily buying “air con” online and assuming the planning system has taken the afternoon off.
The relevant permitted development route is not a general blessing for “air con”. It sits in the air-source heat pump territory: The Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 14, Class G. Even then, the conditions matter. Planning Portal’s heat pump guidance says the unit must not be “used solely for cooling purposes” and must be sited, so far as practicable, to minimise its effect on the building’s appearance and the amenity of the area.
In other words: the law may tolerate your little white box, but it does not have to admire it.
Even where permitted development might apply, the details still matter. Position, size and location can all affect the answer. Conservation areas and listed buildings make everything more sensitive. Front elevations, prominent walls and highway-facing positions are where optimism goes to die.
The practical point is not complicated. If there is an external unit, check the planning position before anyone starts drilling.
In planning terms, that is the moment the domestic appliance starts looking like development. Section 55(1) of the Town and Country Planning Act 1990 defines development as including “the carrying out of building, engineering, mining or other operations in, on, over or under land”. A condenser fixed to the outside of a building may look small, but the law has never measured irritation by cubic volume alone.
Not after installation. Not when the neighbour complains. Not when the buyer’s solicitor raises it. Before.
I appreciate this is a radical doctrine in English property law: read the rules before creating the problem.
Leasehold consent is not admin
In a flat, planning is only one part of the fun. The lease is often the real obstacle.
The installation may require landlord consent, management company consent, RMC approval, RTM company approval or a formal licence for alterations. That is not because lawyers enjoy paperwork, though admittedly we do have a regrettable talent for it. It is because the works may affect the exterior, structure, fire safety, acoustics, drainage and other leaseholders.
A proper application should not just say, “Please can I have air con because I am hot and sad.” However much that is the truth.
It needs to explain what is being installed, where it is going and how the building will be protected. The landlord should want enough information to understand the location of the external unit, the route of pipework and the effect on noise, fire-stopping and future maintenance.
That is not bureaucracy for the sake of it. That is how one person’s cool bedroom does not become everyone else’s building problem.
The alterations covenant matters. A qualified covenant is not the same as an absolute covenant. A covenant where consent cannot be unreasonably withheld is not the same as one that simply says no.
If the covenant is qualified, section 19(2) of the Landlord and Tenant Act 1927 may matter, because a covenant against improvements without licence or consent is generally treated as subject to the statutory proviso that consent is not to be unreasonably withheld. That is useful, but it is not a magic spell. It does not turn an absolute covenant into a qualified one, and it does not make the external wall part of the leaseholder’s demise.
Then comes Duval v 11–13 Randolph Crescent Ltd [2020] UKSC 18, the case that should haunt every breezy “the freeholder can just consent” email. The Supreme Court issue was whether a landlord could licence works that would breach an absolute covenant, where the leases of other flats required the landlord to enforce covenants at another lessee’s request. The works in question involved cutting into walls, which is exactly the sort of physical interference that should make anyone dealing with split air conditioning in flats sit up.
In other words, “just ask the freeholder” is not a complete legal analysis. Sometimes the freeholder can consent. Sometimes the freeholder must act reasonably. Sometimes the freeholder may be boxed in by the leases.
The lease is not a vibe. It is the starting point.
Building regulations and the great British hole in the wall
The physical installation matters as much as the legal paperwork.
A contractor may say they will “just” drill through the wall. In a block of flats, that word should set off a small alarm bell. The wall may be structural. It may be fire-resisting. It may contain insulation, cavity barriers, services, damp protection or part of a cladding system. Since the Building Safety Act entered the room, casually puncturing building fabric should no longer be treated as a harmless domestic adventure.
Even in houses, the electrics matter. A proper system may need suitable capacity, a dedicated circuit, certification and competent installation. “Dave can probably sort it” is not an electrical strategy; it is a future file note.
Then there is condensate. The water has to go somewhere. Not down the brickwork, not onto the neighbour’s balcony, and not into a mysterious pipe that nobody can identify but everyone is sure will be fine.
If the machine cools the room but upsets the building, the installation has failed the property test.
Noise: the neighbour has ears
Noise is where many of these disputes will actually live.
External units hum. Some hum quietly. Some hum obnoxiously. Some start off quiet and become less quiet after three years of heroic neglect. In dense terraces, side returns, mansion blocks, courtyards and lightwells, sound can bounce around beautifully, which is excellent if you are at the opera and less excellent if you are trying to sleep next to someone else’s condenser.
The owner of the unit will call it reasonable climate adaptation. The neighbour will call it a mechanical wasp outside the bedroom. The managing agent will call it “a matter between residents” until enough emails arrive. The local authority may call it a statutory nuisance if things get bad enough.
The statutory nuisance regime is not there for decoration. Councils must investigate noise complaints that could be a statutory nuisance, and noise can qualify where it unreasonably and substantially interferes with the use or enjoyment of a home, or injures health or is likely to injure health. If the council agrees that a statutory nuisance exists or is likely to occur, it must serve an abatement notice.
That is the legal difference between “a gentle hum” and “please remove your climate adaptation from outside my child’s bedroom”.
This is why location matters. A unit that works technically may still be socially idiotic.
There is a difference between discreet cooling and declaring war on Flat 3.
EPCs are looking the wrong way
The EPC system is part of the wider problem because it has trained the market to think in winter. Heating costs, heat loss, insulation, boilers and energy efficiency dominate the conversation.
Those things still matter, but they do not answer the summer question. A flat can be energy efficient and still overheat. A house can have improved insulation and still be miserable during a hot spell. A modern apartment can look sustainable in marketing language while being, in practical terms, a premium greenhouse.
The market needs a better vocabulary for summer comfort.
Passive measures matter. Shutters, shading and sensible ventilation are not glamorous, but they may be more elegant than scattering condensers across every façade in London. Trees help. Design helps. Not building glass boxes for people to slowly roast in would also be a start.
But passive cooling cannot become a pious phrase used to avoid the reality that some existing homes will need active cooling. There are only so many times you can tell someone in a top-floor flat to “keep the curtains closed” before they quite reasonably starts pricing up machinery.
Conveyancers will inherit the mess
This is where the Hound becomes especially cheerful.
Every missing consent begins life as a small job. A wall came down. A window changed. A balcony was decked. A loft was opened. Nothing dramatic, everyone said, until the property was sold and the paperwork was asked for.
Air conditioning will be the same.
On a sale, the buyer’s solicitor will want to know whether planning permission was required, whether building regulations were complied with, whether landlord consent was obtained, whether the management company approved the installation, whether the unit sits within the seller’s title or demise, whether there have been noise complaints and whether anyone knows where the electrical certificate is.
At that point the seller will say, “It was here when we bought.”
Of course it was. That sentence has powered half the enquiries in residential conveyancing.
For houses, the issue may be planning, covenants, conservation, building regulations or neighbours. For flats, add leasehold consent, retained structure, management control and the possibility that the landlord should never have consented in the first place.
A perfectly functioning air conditioning system can still be a title defect with a remote control.
Managing agents need to get ahead of this
Blocks need policies now, not after the façade has acquired its fifth condenser and the residents’ WhatsApp group has started using the word “tribunal”.
A sensible policy does not need to be a Victorian novel. It needs to cover three things clearly: where units can go, what technical evidence is needed, and who is responsible for maintenance, damage and removal.
That is not anti-leaseholder. It is anti-chaos.
A clear policy gives residents a route to consent, protects the building and avoids the worst kind of management decision-making: random discretion dressed up as principle. One leaseholder should not be allowed a unit because they asked nicely while another is refused because the managing agent had a difficult morning.
The issue is coming. Pretending otherwise is not a strategy.
The Hound’s view
Air conditioning is going to become normal in British homes faster than the property industry wants to admit.
Not everywhere. Not always. Not without control. But normal.
The old moral objection to domestic cooling will not survive repeated heatwaves, overheated nurseries, unliveable loft rooms and vulnerable residents being told to rely on a tower fan and positive thinking. Property professionals need to stop treating overheating as a lifestyle complaint and start treating it as part of habitability, value and risk.
That does not mean every house should bolt a condenser to the front wall. It does not mean every leaseholder should be allowed to drill through the façade because they had a sweaty Tuesday. It does not mean planning, conservation, fire safety, neighbour amenity and building management can be brushed aside in the name of chilled air.
It means the conversation needs to mature.
The external unit is the legal moment. Once the solution leaves the room and attaches itself to the building, the building gets a vote. So does planning. So does the lease. So does the neighbour. So does the future buyer’s solicitor.
The Hound is not anti-air conditioning. The Hound is anti-missing consent, anti-bad installation and anti-midnight humming box attached to someone else’s wall.
Cool the house. Cool the flat. Cool the nation, frankly.
But do not pretend the little white box outside is legally invisible.
It is not.
It is the future of residential property, humming gently on a bracket.
Need help?
This article, which was first posted on LinkedIn, is intended as general commentary only. It is not legal advice. The law and guidance referred to above are stated as at 7 July 2026 and are focused on England. Air conditioning, heat pump, leasehold and external plant issues are highly fact-specific. The correct answer will depend on the title, the lease, the building, its location, the planning history, any conservation or listed status, the proposed system, the position of the external unit, the route of pipework, the electrical works, the noise impact, the management structure and the documents already available.
Contact our Residential Property team
For more information about Bishop & Sewell’s residential property services please contact Charlie Davidson Senior Associate in the firm’s Residential Property team: cdavidson@bishopandsewell.co.uk or follow Charlie on LinkedIn.
