KEEPING cool while you’re sleeping can be made easier using handy devices, such as an air cooler or air conditioner.

But how much does it actually cost to keep these machines running for the night?

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Keeping cool in the heat can be helped by using devices like an air cooler or air conditioner Credit: Alamy

But keeping these machines running all night can add to energy bills

Firstly, it’s important to understand the difference between the different types of cooling devices.

An air cooler is a portable device that works essentially as a more powerful fan.

Warm air from the room is pulled through damp pads inside the unit, where evaporation cools it down before it’s pumped back out.

On the other hand, an air conditioner is a type of heat-extraction machine, absorbing warm air and sending it outside via a compressor and condenser.

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Air conditioners can be portable, using a tube going through the window, or be a split installed indoor unit that directly links to an outdoor unit.

The two devices also reduce temperatures at different rates.

While an air cooler will typically lower the heat by around 2 to 5C, an air con unit cools a room dramatically, reducing the warm temperatures by 10 to 15C.

However, this mighty cooling effect comes at a price.

Portable air conditioners can set you back anywhere between £300 – £1,000 and a split AC unit can cost up to £4,500 including installation.

The running costs are also higher.

Depending on the efficiency of your model, a 2.5kW portable AC can consume between 0.3 and 1.5kWh, meaning an hourly cost of 8 – 39p.

Running this type of unit overnight for an average of eight hours over a 60-day summer period will set you back between £38.40 – £187.20.

A split AC system can be more economical in the long run due to better efficiency and smart zoning.

The average air cooler will cost around £100 – £400, a more budget-friendly alternative for those looking to lower the heat.

Using around 80 – 150 watts, the devices cost 2 – 4p to run, based on the Ofgem UK price cap for April to July 2026 of electricity rates of 24.67 pence per kWh.

This means running a portable air cooler over summer for an average of eight hours a night will only set you back £9.60 – £19.20.

It is worth noting that despite being both cheaper and more efficient to run, air coolers can increase the humidity of a room, whereas air conditioning will lower the humidity.

To calculate the running costs of your air cooler or air conditioner, you’ll need to know how much electricity it uses by finding out the wattage.

Convert the wattage to kilowatts by dividing by 1,000, then multiply by the number of hours you used the device for to give you the kilowatts per hour.

Then multiply the kilowatts per hour by the rate (24.67 pence per kWh).

In summary, the equation is: cost = power (kilowatt) x time (hour) x cost of 1 kWh (pence).

Or you can use a handy electricity cost calculator to figure out the overall costs.