EXPERT ADVICE
Air conditioning: Everything you need to know
Updated 01/26
By: Content Team
With summer temperatures affecting our sleep and working from home becoming more prominent, now is a great time to invest in an air conditioning unit.
Air conditioning can make a big difference to everyday comfort at home – from sleeping better on warm nights to keeping rooms usable during heatwaves.
This guide explains how air conditioning works, the main system types available in the UK, typical installation costs, and what to think about before getting started.
Overview
Air conditioning systems cool indoor spaces by removing heat and controlling humidity.
Unlike fans, which only circulate air, air conditioning actively lowers room temperature and can create a more consistent indoor environment.
Modern systems are now common in UK homes, particularly for:
Bedrooms
Home offices
Loft conversions
Flats and apartments
Many units can also provide heating, making them useful year-round.
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What is air conditioning?
Air conditioning is a way of cooling indoor spaces by removing heat from the air. Unlike fans, which only move warm air around, air conditioning actually lowers the temperature in a room.
It works by pulling warm air in, cooling it, and circulating cooler air back into the space. The heat that’s removed is released outside the building.
Many modern air conditioning systems also reduce humidity and can provide heating, making them useful all year round in UK homes.
If you’re planning air conditioning installation, consider how you’ll use the room in winter too. Systems with heating modes can offer added flexibility beyond summer cooling.
How does air conditioning work?
Air conditioning uses a continuous cooling cycle:
1. Heat is absorbed
Warm air is drawn into the unit and passed over a cold evaporator coil. Heat is removed and cooler air is circulated back into the room.
2. Heat is released outside
The refrigerant is compressed and moved to the outdoor unit, where the heat is released into the outside air.
3. The cycle repeats
The refrigerant cools, returns indoors, and the process continues until the set temperature is reached.
Types of air conditioning units
Choosing the right system depends on how often you need cooling and whether you want a fixed or portable option.
Monoblock (portable) air conditioners
Single-unit systems that plug into a standard socket and vent hot air through a window or door.
Good to know:
Lower upfront cost
No professional installation needed
Can be moved between rooms
Less efficient than fixed systems
Some warm air can re-enter the room
Often used for short-term or occasional cooling.
Split air conditioning systems
Permanent systems with an indoor unit and an outdoor condenser, installed by a professional.
Good to know:
More efficient and quieter
Better temperature control
Ideal for rooms that regularly overheat
Fixed in place
Requires professional installation
Multi-split systems can cool multiple rooms from one outdoor unit.
What size air conditioning unit do I need?
Cooling capacity is measured in BTUs (British Thermal Units).
As a rough guide:
Small bedrooms or offices: 5,000–7,000 BTUs
Medium rooms: 8,000–10,000 BTUs
Large or open-plan spaces: 12,000 BTUs+
Other factors include:
Ceiling height
Insulation
Number of windows
Sun exposure
An air conditioning installer can assess your space and recommend the right size.
Whether you need help understanding air conditioning installation costs or hiring the right installer, Checkatrade is here to help.
How much does air conditioning cost in the UK?
Costs vary depending on system type, room size, and installation complexity. Here are some average estimated costs for air conditioning in the UK:
A 12000 BTU wall-mounted unit – £620 - £890
A 12000 BTU portable air conditioning unit – £350
Labour costs
Average installation labour costs –£910 - £1,310
For a split air conditioner unit –£960 - £1,380 per unit
For an average ducted air conditioning unit – £1,460 - £2,100
It's always worth getting multiple quotes so you can compare and make sure you're being quoted fair and competitive prices.
Learn more about pricing in our guide to air conditioner installation costs.
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Do you need planning permission for air conditioning?
In most cases, planning permission isn’t required for domestic air conditioning.
You may need permission if:
You live in a listed building
Your property is in a conservation area
The outdoor unit significantly alters the building’s appearance
If unsure, check with your local planning authority before installation. You might also want to read our guide to air conditioning building regulations.
Installation, servicing, and maintenance
Regular servicing helps keep air conditioning systems efficient and reliable.
Servicing may include:
Cleaning filters and coils
Checking refrigerant levels
Inspecting electrical components
Testing performance
You may need repairs if you notice:
Reduced cooling
Unusual noises
Leaks
Control issues
Routine maintenance can reduce long-term running and repair costs.
On Checkatrade, you'll only find trades who meet our high standards and pass up to 12 checks.
Related air conditioning services
You can also explore our guide to air conditioning troubleshooting, if you're having issues with your system.
Need help finding a tradesperson?
Search by postcode or use the Checkatrade app to find air conditioning installers, servicing specialists, and repair services near you.
You can also check out our useful guide to finding air conditioning installers near you.
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FAQs
How much does air conditioning cost to run?
Running costs depend on unit efficiency, usage, and electricity prices. Modern systems are generally more energy-efficient than older models.
Is air conditioning legal in the UK?
Yes. Air conditioning is legal in domestic and commercial properties when installed correctly.
Do I need a professional to install air conditioning?
Yes. Fixed systems must be installed by a qualified professional, particularly where refrigerants are involved.
Can air conditioning heat my home too?
Many modern systems include heat pump technology, providing both heating and cooling.
How long does installation take?
Single-room installations usually take 4–8 hours. Larger systems may take longer.
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