How much does air con cost to run? Cost guide
If you’re looking into air conditioning, cost might be a main concern — both upfront and ongoing.
The honest answer is that air con costs vary quite a bit. In fact, running costs depend on how you use the system, your home and your energy tariff. But once you understand what affects those costs, it becomes much easier to manage them.
Published on 22nd May 2026 by:
Ian Brown, Senior Commercial Manager, Installs
Is air con expensive to run in the UK?
Air conditioning doesn’t have to be expensive to run in the UK, but costs can vary depending on your electricity tariff, how often you use it, the size of the space, and how efficient your system is.
That said, modern air conditioning units are generally quite efficient, especially those with higher energy ratings. Air conditioning units installed through British Gas are A++ for cooling. In practice, it often comes down to how you use it. Keeping a steady, comfortable temperature tends to use less energy than switching it on and off and cooling one room at a time is usually more cost-effective than trying to cool the whole house.
If you use it sensibly, you’ll find that the running costs are very manageable.
How can you estimate your air conditioning running costs?
Working out the running cost of an air conditioner is fairly straightforward once you know what to look for.
You’ll need two things:
- The power of your unit (in kW) — usually found on the energy label or in the product specifications
- Your electricity rate (pence per kWh) — shown on your energy bill
You can then use a simple calculation:
Energy used (kW) × electricity price (p/kWh) = cost per hour
Note: The temperature outside will impact how much energy you use to reach your desired indoor temperature.
What affects the cost of running air conditioning?
As mentioned, there isn’t a fixed price for running air conditioning, but a few key factors make the biggest difference:
-
Electricity price – your unit rate will directly affect how much you pay
How often you use it – occasional use costs less than running it all day
Room size and layout – larger or open spaces take more energy to cool
Insulation – well-insulated homes keep cool air in for longer
System type – newer systems are generally more efficient
Energy efficiency rating (SEER) – systems with a higher SEER rating use less energy to deliver the same level of cooling
Energy use - the temperature outside will impact how much energy you use to reach your desired indoor temperature
This is why the cost of air conditioning can look quite different from one home to another.
How energy efficiency affects running costs
If you’re comparing systems, efficiency ratings are a good place to start. Air conditioning units often come with an energy rating from A+++ downwards, which gives a simple idea of how efficient the system is. Behind that label is a more detailed measure called the SEER rating (Seasonal Energy Efficiency Ratio), which shows how efficiently the unit uses energy over a typical cooling season.
Put simply, the higher the SEER rating, the less electricity the system needs to deliver the same level of cooling or heating. So, while a more efficient unit may cost more to buy upfront, it can help reduce running costs over time — something worth keeping in mind when choosing a system.
Is it cheaper to cool one room or the whole house?
Cooling individual rooms is a lot more cost-effective than running a system across your entire home.
If you’re using a system that allows zoning or separate room control, you can focus on the spaces you’re actually using — such as a bedroom at night or a home office during the day. You’ll find that this approach can make a noticeable difference to overall energy use.
Does using air conditioning all day cost more?
Understandably, running your system for longer periods will naturally increase energy use, but how it’s used also matters. That said, keeping a steady, moderate temperature is often more efficient than turning the system on and off at extremes. Many systems work best when maintaining a consistent temperature rather than cooling a room from very warm each time.
Are portable or wall mounted air conditioners cheaper to run?
Wall mounted air conditioning systems are usually cheaper to run than portable units, especially with regular use. This is because wall mounted systems use a separate outdoor unit to move heat outside more efficiently.
Portable air conditioners sit inside the room and remove warm air through a hose, which can let heat leak back in and make them work harder. That said, they can still be useful for short-term or occasional use, but wall mounted systems are generally the more energy-efficient option over time.
How to keep air conditioning running costs down
A few simple habits can also make a noticeable difference:
- Set your temperature to around 18-21°C 1
- Keep doors and windows closed while it’s running
- Use timers or smart controls where possible
- Clean filters regularly to keep the system efficient
- Block out direct sunlight with blinds or curtains
These small changes can help keep energy use — and costs — significantly lower over time.
How much does an air conditioning unit cost?
If you’re also thinking about installation, upfront cost is another part of the picture and something you’ll need to factor in.
The cost of an air conditioning unit will depend on the type of system, the size of your home, and how many rooms you want to cover. For example, a simple wall-mounted system for one room will cost less than a multi-room setup.
So rather than focusing on a single number, it’s usually more helpful to look at overall value, including efficiency, performance and long-term running costs.
Thinking about air conditioning?
If you’re considering air conditioning, choosing the right system can make a real difference to both comfort and running costs.
With British Gas, you can get a clear online quote, expert guidance on energy-efficient options, and installation from trusted partners. There are flexible ways to pay — including spreading the cost or paying in full, subject to status and credit checks — along with a 5-year manufacturer guarantee on air conditioning units that are serviced annually, so you know exactly what to expect both upfront and over time.