Flats and apartments can become extremely uncomfortable during a UK heatwave. Upper-floor rooms, large windows, limited airflow and shared building rules can all make it harder to keep your home cool.
If your flat was too hot during the latest spell of warm weather, you are not alone. More people are now searching for practical ways to cool flats, apartments, rented homes and leasehold properties without choosing the wrong type of air conditioning.
In this guide, we explain the best air conditioning options for flats and apartments in the UK, including portable units, compact air conditioners, water-cooled systems and wall-mounted air conditioning where installation is possible.
Why flats and apartments get so hot
Flats often overheat faster than houses because they can have fewer windows, limited cross-ventilation and less control over external walls or outdoor space. Top-floor flats, south-facing apartments and modern buildings with large glass areas can become especially hot during long periods of sunshine.
The most common problems include:
- Bedrooms staying hot at night, making it difficult to sleep
- Living rooms with large windows heating up during the day
- Top-floor flats holding onto heat from the roof and surrounding building
- Limited options for outdoor units because of building rules or leasehold restrictions
- Rented flats where permanent installation may not be possible
- Balconies or windows that are not suitable for every type of cooling system
Fans can help move air around, but they do not actually lower the room temperature. If your flat stays hot for several days at a time, air conditioning may be the most effective solution.
Can you install air conditioning in a flat?
Yes, air conditioning can often be used in flats, but the right option depends on the property.
Before choosing a system, it is worth checking:
- Whether you own or rent the flat
- Whether the property is leasehold
- Whether you need landlord, freeholder or management company permission
- Whether an outdoor unit can be fitted externally
- Whether there is suitable access for installation
- Whether your windows can work with a portable air conditioner hose kit
- How much noise is acceptable for bedrooms or neighbouring properties
If you cannot fit an outdoor unit, you may still have good options, including portable air conditioners, compact air conditioning units for flats and apartments, or water-cooled DIY air conditioning.
Best air conditioning options for flats and apartments
There is no single best air conditioner for every flat. The right choice depends on whether you want fast cooling, fixed cooling, quiet operation, landlord-friendly installation or a system for more than one room.
1. Portable air conditioners
Portable air conditioners are often the easiest option for flats because they do not usually require fixed installation.
They work by cooling the air in the room and venting warm air outside through a hose, usually through a window. This makes them a practical choice for bedrooms, home offices and living rooms where you need fast cooling during hot weather.
Best for: rented flats, bedrooms, home offices, occasional heatwave cooling and customers who cannot install an outdoor unit.
Things to consider: portable units need somewhere to vent warm air, and they are usually more noticeable in the room than a wall-mounted system.
2. Compact air conditioning units for flats
Compact air conditioning units for flats and apartments are ideal when space is limited.
These are useful for smaller bedrooms, studio flats, compact living rooms and apartments where a large unit would be unnecessary or difficult to place.
Best for: smaller flats, bedrooms, studios, home offices and single-room cooling.
Things to consider: always check the room size before buying. A compact unit can be very effective in the right space, but it may struggle if the room is too large, too sunny or poorly insulated.
3. Water-cooled air conditioning
Water-cooled DIY air conditioning can be a useful option where a traditional outdoor unit is not practical.
This can make it relevant for some flats, apartments and properties where external condenser units are restricted. It may also be worth considering where the appearance of the outside of the building cannot be changed.
Best for: flats where outdoor units are difficult, leasehold properties, apartments with external restrictions and homes where a standard split system is not suitable.
Things to consider: suitability depends on the property, so check the product details carefully before buying.
4. Wall-mounted air conditioning
Wall-mounted air conditioning systems can be the best long-term solution if you are allowed to install one.
These systems are usually quieter, neater and more efficient than portable units. Many also provide heating in winter, making them useful beyond summer.
For flats, the main question is usually whether an outdoor unit can be fitted. This may depend on permission from the landlord, freeholder, building management company or local rules.
Best for: owned flats, long-term homes, bedrooms, living rooms and apartments where installation is approved.
Things to consider: check permission before buying, especially if the outdoor unit would be visible externally or fitted to a shared part of the building.
5. Easy-fit air conditioning
Easy-fit air conditioning may be suitable for some flats where a more straightforward fixed system is required.
These systems are popular with homeowners who want something more permanent than a portable unit, but with a simpler route than traditional installation.
Best for: suitable owner-occupied flats, apartments with outdoor unit permission and homeowners looking for fixed cooling.
Things to consider: easy-fit does not mean suitable for every flat. You still need to check whether the property can take the system and whether any permissions are needed.
Best air conditioning for rented flats
If you rent your flat, a portable air conditioner is usually the simplest starting point because it does not normally require permanent changes to the property.
Portable units can be moved between rooms and taken with you if you move home. They are especially useful if you only need to cool one room, such as a bedroom at night or a home office during the day.
You may also want to look at landlord-friendly air conditioning and heat pumps for rentals if you are comparing options that may be more suitable for rental properties.
Best air conditioning for leasehold flats
Leasehold flats can be more complicated because the outside of the building, walls, balconies and shared spaces may be controlled by a freeholder or management company.
Before buying a fixed air conditioning system, check whether you are allowed to:
- Fit an outdoor condenser unit
- Drill through an external wall
- Place equipment on a balcony
- Make visible changes to the outside of the building
- Install pipework or drainage
If permission is difficult, a portable or water-cooled option may be more realistic.
What size air conditioner do you need for a flat?
The right size air conditioner depends on the room, not just the property type. A small bedroom in a flat may need a different system from a large open-plan living room with full-height windows.
Important factors include:
- Room size
- Ceiling height
- Window size and direction
- Whether the room gets afternoon sun
- How many people use the room
- How much heat comes from appliances, computers or cooking
- Whether the flat is on the top floor
Before choosing a unit, use our guide:
What Size Air Conditioner Do I Need?
Which room should you cool first?
If you only want to cool one room in your flat, start with the space that affects your comfort the most.
Bedroom
For many people, the bedroom is the priority. Hot nights can make it difficult to sleep, especially in top-floor flats or rooms that hold heat from the day.
For bedrooms, consider noise level, room size and whether you need cooling every night or only during occasional heatwaves.
Living room
If your living room has large windows or gets direct sun, it may become the hottest room in the flat. A portable, compact or wall-mounted air conditioner can help make the main living space more comfortable.
Home office
Working in a hot flat can quickly become uncomfortable, especially with a computer, monitor and other equipment adding extra heat. A compact unit or portable air conditioner may be enough for a small home office.
Open-plan kitchen and living space
Open-plan flats can need more cooling power because the air conditioner may be dealing with a larger space, cooking heat and multiple windows. Check the size carefully before choosing a unit.
Portable vs fixed air conditioning for flats
Portable and fixed systems both have their place. The best choice depends on whether you are looking for convenience or long-term comfort.
| Option | Best For | Main Benefit |
|---|---|---|
| Portable air conditioner | Rented flats and single rooms | No fixed installation in most cases |
| Compact air conditioner | Small bedrooms, studios and offices | Good for limited space |
| Water-cooled air conditioning | Flats where outdoor units are difficult | Alternative to a traditional outdoor condenser |
| Wall-mounted air conditioning | Long-term cooling where installation is approved | Neater, quieter and more permanent |
| Easy-fit air conditioning | Suitable owner-occupied flats | More permanent than portable cooling |
Best products for cooling flats and apartments
If your flat struggled during the latest heatwave, these air conditioning options are a strong place to start.
Portable Air Conditioning Unit - 2.0kW 7000 BTU
A compact portable air conditioning unit for smaller rooms, bedrooms and home offices. A practical option for flats where fixed installation is not possible.
View Portable Air Conditioning Unit - 2.0kW 7000 BTU
Portable Air Conditioning Unit - 2.9kW 10000 BTU
A stronger portable option for larger bedrooms, living rooms and open-plan flat spaces. Useful when a smaller compact unit may not be enough.
View Portable Air Conditioning Unit - 2.9kW 10000 BTU
Lux Air Portable Air Conditioning Unit 2.5kW 9000 BTU
A practical portable air conditioner for fast single-room cooling. Ideal for bedrooms, home offices and flats where a fixed system is not suitable.
View Lux Air Portable Air Conditioning Unit 2.5kW 9000 BTU
Samsung Cebu S2 High Wall Air Conditioning System
A sleek wall-mounted system for flats and apartments where fixed installation is possible. A good long-term option for bedrooms, living rooms and home offices.
View Samsung Cebu S2 High Wall Air Conditioning System
Mitsubishi Electric HR Wall Mounted Air Conditioning System
A trusted wall-mounted system from Mitsubishi Electric, suitable for homeowners looking for reliable long-term cooling from a recognised brand.
View Mitsubishi Electric HR Wall Mounted Air Conditioning System
Need help choosing air conditioning for your flat?
The best air conditioning for a flat depends on your room size, whether you rent or own, and whether fixed installation is possible.
Start by deciding whether you need a portable, compact, water-cooled or wall-mounted system. Then measure your room and check the product details carefully before buying.
You can explore the most relevant collections here:
- Compact Air Conditioning Units for Flats & Apartments
- Portable Air Conditioners
- Water-Cooled DIY Air Conditioning
- Landlord Friendly Air Conditioning & Heat Pumps
- High Wall Mounted Air Conditioning Systems
If you are not sure what size system you need, use our air conditioner size guide or contact the CoolEasy team for advice.
FAQs
What is the best air conditioning for a flat?
For many flats, a portable or compact air conditioner is the easiest option. If fixed installation is allowed, a wall-mounted air conditioning system may be a better long-term solution.
Can you have air conditioning in a rented flat?
Yes, but portable air conditioning is usually the simplest option because it does not normally require permanent changes to the property. Always check your tenancy agreement before making any changes.
Can you install wall-mounted air conditioning in a flat?
Wall-mounted air conditioning may be possible in some flats, but you may need permission from the landlord, freeholder or building management company, especially if an outdoor unit is required.
Do portable air conditioners work in flats?
Yes, portable air conditioners can work well in flats when correctly sized for the room and properly vented outside through a window or suitable opening.
What size air conditioner do I need for a flat bedroom?
The right size depends on the room size, ceiling height, windows, insulation and sun exposure. Always measure the room before buying and use an air conditioner size guide.
What if my flat cannot have an outdoor unit?
If an outdoor unit is not possible, look at portable air conditioners, compact units or water-cooled air conditioning options that may be more suitable for flats and apartments.
