- Planning permission is usually not required unless you are in a conservation area or a listed building.
- Cooling-only systems are not covered by permitted development rules
- If in doubt, talk to your council.
If you're looking for a way to avoid the sweltering heat of another heatwave that's coming soon, air conditioning looks awfully tempting, to the point that in the UK, portable air conditioning units are either sold out almost everywhere or selling for ridiculous money on eBay, while air conditioning installers are booked for the future.
With future summers expected to be even hotter, many of us are considering fully installed air conditioning as a long-term investment for our homes and our health, and that means we are likely to encounter a lot of confusion and misinformation about what can and cannot be done under UK planning and building regulations.
That confusion has been fueled in part by social media and highly misleading newspaper headlines suggesting that Net Zero-crazed councils are demanding innocent homeowners “RIP OFF” their expensive installations.
The UK government's Ministry of Housing, Communities and Local Government (MHCLG) says such coverage is incorrect. “In most cases, no building permit is required to install [air con] for a small house if it did not materially affect the appearance of the building from the outside.
The most sensational headlines have been about air conditioning in London and reference the London Plan, a city-specific rule that prioritizes passive cooling and discourages extensive use of air conditioning due to the heat it emits outside, which can contribute to creating heat islands in built-up areas.
As a spokesperson for the Mayor of London told The Telegraph: “The current London Plan does not rule out air conditioning; its policy only applies to large developments and requires new developments to address the risk of overheating from the outset, through measures such as shading, ventilation and other cooling design features.”
If you look at the details of newspaper stories, you will usually find that the problem was not the air conditioning itself, but how and where it was installed.
The problem is that even the previous Government press release that says “Air conditioning units are not banned” also says: “However, there is no general rule. People should talk to their council to check the rules, and councils should take a common sense approach.” So that doesn't completely clear things up, but there is are basic rules that apply widely, which are then modified depending on the situation of the city council.
So here's an overview of the rules you need to know when you're considering investing in permanent air conditioning, so you at least know where you're starting from and can analyze your area's circumstances from there.
In this article we will focus exclusively on adding home air conditioning to an existing residential home that you own. If your home is a leasehold in England, you may need to obtain the landlord's consent in addition to the other criteria.
What kind of home you have matters
The rules depend a lot on the type of house you have. If you are in a listed building you will definitely need to apply for the listed building permit; if you are in a conservation areaThere will be restrictions on changing the appearance of your home, so there will be limits on where you can place the outdoor unit on the outside of your home.
If your house is neither listed nor in a conservation areaso the rules are largely common sense: Under the rules for 'Permitted Developments' you do not need planning permission as long as your air conditioner meets some reasonably simple technical and location criteria.
The specific criteria are similar across the UK and I have linked them here:
If you are unsure whether your scheme meets the permitted development criteria, we strongly recommend that you speak to your council's planning department – if you are wrong, the council can force you to delete the system on your own. You don't want to make what could be a very costly mistake.
What are the basic standards for domestic air conditioners in the UK?
The ground rules (before entering conversation areas, etc.) differ depending on the type of air conditioning you are considering installing.
If your air conditioner can heat and cool then it is generally permitted under Permitted Development rules under your Class G permitsthat your local council applies according to common sense.
Provided your external condensing unit (the part of an installed air conditioner that goes outdoors) or heat pump is not too big, too noisy, too visible or too close to your neighbors, you usually do not need planning permission.
That is This is not the case if the air conditioner cools but does not have a heating element either.. This requires a planning permit and local councils are keen to discourage this type of installation.
How big can your air conditioning be in the UK?
Class G permits allow you to install air conditioning on your property or its “curtilage,” which is the land associated with and immediately surrounding it, including any additional buildings. If you live in a castle, protection is anything within the castle walls; If you are in a semi-detached house, the construction usually means your garden, driveway and garage, if you have one.
Most modern air conditioning systems are air source heat pumps (ASHPs), meaning they can cool and heat the air they inhale and exhaust.
Class G permits were revised in 2025 to specifically include outdoor units of ASHPs and state that in a permitted development:
- You can have up to two ASHPs in a single-family home or bungalow
- If you live in a semi-detached or semi-detached home, you will only be able to have one ASHP
- If you live in a block of two stories or more, that also limits you to an ASHP.
for a semi-detached, semi-detached or detached house the ASHP must not be greater than 1.5 cubic meters. For floors the limit is 0.6 cubic meters.
A cubic meter measures 1 m wide, 1 m high and 1 m deep. That's larger than a free-standing refrigerator – sizes differ by manufacturer and product, but as an example, the outdoor units for Toshiba's current RAS multi-split air conditioners range from 0.12 m³ to 0.25 m³ with the largest model measuring 890 x 900 x 320 mm, which easily fits within household regulations.
What type of air conditioning can I install?
Under Class G your equipment must comply with the Microgeneration Certification Schemeor MCS for short. The regulations are a little strange here because, while an air source heat pump must comply with the MCS, it does not need to have a certificate. MCS details are online here.
Where can I install my air conditioning?
The rule that prevented you from installing your outdoor unit within 1m of neighboring properties has been removed. However, Your installation should not negatively impact your neighbors with noise– The noise level of your outdoor unit cannot exceed 42 decibels measured one meter from your nearest neighbor's door or window. MCS compliant units will not exceed that limit.
You The outdoor unit cannot be installed on a sloped roof or within one meter of the edge of a flat roof..
If you are not in a conservation area or listed building, You can install the outdoor unit on the front wall as long as it is on the ground floor..
If you are in a conservation area, you cannot install an outdoor unit on any elevation facing a road.
The location of your outdoor unit is where common sense criteria come into play: the outdoor unit, its wiring and any ductwork should be located in such a way that “so far as practicable, they are located in a manner that minimizes their effect on the external appearance of the building” and “in a manner that minimizes their effect on the amenity of the area.”
If you have a wind turbine in your yard, you're out of luck: Class G does not grant permission for any air conditioning installation on properties with a turbine within its premises.
Your air conditioning installer will be very familiar with the regulations and should be able to ensure that your air conditioning meets all relevant requirements, but if you have any concerns, speak to your local council's planning officers, because, again, you don't want them to have grounds to force you to remove it.
What do I do to make sure there are no special rules in my area?
Your council is likely to have an entire website dedicated to helping with planning information, potentially including a map showing whether your home is included in any conservation areas and what the specific orders are around those areas, so you can determine if they would affect the installation of air conditioning.
If not, or if it's still unclear, your council will have a system for planning permission inquiries, so you can ask if what you're planning needs a permit without going through the process, and that means if you need one, they can tell you exactly what is needed.
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