How much does it cost to leave a fan on overnight?

BRITS will be struggling to keep cool as the UK is set for 30C sunshine over the next few weeks.

There’s one great solution to beating the heat though, with a fan. But how much do they cost to run?

Getty – Contributor

We take a look how much it costs to use a fan in a heatwave[/caption]

Nothing is worse than sleeping in a hot and stuffy room over night, so many will leave an electric fan on whilst they go to bed.

But this can be a costly move as leaving fans on for a long time will eat into a significant chunk of your energy bill.

A spokesperson for the Met Office told the Sun: “Temperatures are going to stay warm, locally very warm, throughout this week and into the next.”

So it’s worth making yourself aware of how expensive your fan will be to run especially as the hot weather isn’t going away anytime soon.

How much energy does a fan use up?

To work this out you need to find out how much electricity your fan uses.

Finding out the “wattage” of a fan will give you the answer and tell you the amount of power it’s using.

Then you need to find the total output you will have to turn that wattage into kilowatt hours.

There’s a bit of maths involved as first you divide the kilowatt hours by 1,000. This will give you how much output is used in one hour.

So if your fan is 70 watts output on its high setting and you always use this, divide 70 by 1000 = 0.07.

Then times this number by the number of hours you’ve used the fan.

For example, if you’re using it for 12 hours per night then 0.07kW x 12 hours will mean 0.84kW output.

How much does it cost to leave a fan on overnight?

Now that you know your kilowatt output, you need to times it by the amount you pay for 1 kW of electricity.

Find this amount on your energy bill.

For example, if a kW costs 15p on your bill the sum will be: 0.84kW x 15  = 12.6p.

The equation is: Cost = power (kilowatt) × time (hour) × cost of 1 kWh (pence).

Research from energy-saving assistant Loop shows that a 0.04kW fan running overnight would cost on average 6p.

In the meantime a 1.003kW air conditioning unit running for the same time would cost £1.44.

Of course, costs will vary depending on the type of fan you have, how long you’re using it for and how much your energy costs.

Plus it will depend on the cost of your tariff.

Just be aware that those with allergies and asthma have been warned that fans could be making their symptoms worse.

The difference between Kilowatts and Watts

IF you're trying to calculate energy usage the terms can be confusing, according to OVO Energy

kW stands for kilowatt. A kilowatt is simply 1,000 watts, which is a measure of power.

A kilowatt hour (kWh) is a measure of energy.

So a 1,000 watt drill needs 1,000 watts (1 kW) of power to make it work, and uses 1 kWh of energy in an hour.

That’s why, if you leave a TV or computer on standby, it is still using power and creating a kWh cost on your energy bill

Do fans make a room cooler?

Although fans can’t make a room cooler, they can make you feel cooler.

The air moving over your skin can lower your body temperature but won’t do much about the heat inside a room.

So if you don’t plan on being in the room there’s no point of leaving the fan on as it won’t do anything to the heat inside the room itself.

How else can I keep cool in the heat?

Relying on just a fan to keep you cool could be a very expensive way to tackle the heatwave this year, but there are other options you could try.

Family handyman has come up with ideas that include spraying a sheet with cold water covering a window opening.

With this hack, the breeze will hit the sheet and pass through the cool, damp fabric, which can help bring the temperature down in your home.

The site also suggest trying insulated window films that you can buy to stick on your window.

The cheap to purchase alternative can help cut energy costs as well as offer privacy while you can still enjoy the view and light from outside.

They are also designed to provide up to 98% infrared heat reduction compared to unprotected windows, and reduce the temperature coming in.

They’re only about £7 to buy from places like Amazon as well.


If you do fancy basking in the summer sun though Argos is selling a £20 inflatable sun lounger that’s perfect for the coming heatwave.
Once you’re done tanning on that you might want to take a dip in a pool from our round-up to cool off.
It’s not just us struggling in the heat, here’s how to keep your pets cool as well a warning signs to look out for.

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