Measuring your energy efficiency

Cutting your energy bills

Measuring your energy efficiency

Article 1 of 4

Put us to the test

Our Test Labs compare features and prices on a range of products. Try Which? to unlock our reviews. You'll instantly be able to compare our test scores, so you can make sure you don't get stuck with a Don't Buy.

Measuring your energy efficiency

Make sure you know how to measure the electricity you're using, so you can find out how to cut down on your bill.

Once you know how much electricity you're using, you can work out how to save electricity and increase your energy efficiency. 

Do you know how much electricity you use at home every day? 

The cost of boiling a kettle, turning on the lights or charging your mobile phone all add up. With the price of electricity on the rise, there has never been a better incentive to start saving energy.

As well as saving you money by cutting your electricity bill, becoming more energy efficient will also mean less burning of fossil fuels. Burning fossil fuels to produce electricity increases carbon emissions, which are linked to climate change.

The easiest way to save on electricity is to make sure you're on the cheapest energy tariff. Use our independent switching service, Which? Switch, to look for a cheap electricity tariff.

Measuring electricity efficiency

Electricity consumption is usually measured in kilowatt hours, or kWh for short. An electrical item rated at 1,000W switched on for one hour uses 1kWh of energy (1,000W = 1kW).

  • A 20W CFL-type light bulb (equivalent to a 100W traditional bulb), on for one hour, uses 0.02 kWh of electricity
  • A 10W CFL-type light bulb (equivalent to a 60W traditional bulb), on for one hour, uses 0.01 kWh of electricity
  • A 10W CFL-type light bulb, on for two hours, uses 0.02 kWh of electricity

A good way to get a handle on how much electricity you're using is to set up an energy monitor. These handheld gadgets can tell you in near real time exactly how much you're using in pounds and pence or kWh. 

Find out more about them in our energy monitor guide.

Electricity costs on your bills

Electricity suppliers sometimes refer to each kWh of electricity as a 'unit of electricity'. They have a charge for each kWh (or each unit) - this is currently around 11-12p.

So having a 20W CFL bulb on for one hour uses 0.02 kWh of electricity – 0.33p. With many household bulbs and electrical appliances being on for several hours a day, it's easy to see how electricity costs can add up.

Most suppliers also have a daily standing charge for being connected to their electricity supply, before adding their charge per unit used. Some also charge a higher rate up to a certain amount of electricity used. Find out how much energy your home appliances use, and how it adds up, with our energy cost calculators.

Compare and switch suppliers

Choose the fuel type
to compare:

Gas and electricity Electricity
only
Gas only

Start saving electricity

There's lots you can do to start saving energy and money. For example, you can invest in more energy-efficient household appliances when it's time to replace them. 

When we test appliances in our lab, we measure how much electricity each one uses. This means you can use our reviews to pick the products that won't hike up your energy bill. 

Or, if you want to go straight to the heart of the problem, consider generating your own electricity using solar panels or switching to a cheap energy deal.

But it's not all about grand gestures. Smaller changes, such as unplugging your mobile phone's charger when the battery is fully charged, may shave only a few pence off your electricity bill. But in the long run, this can have a huge impact on the environment if we all get into the habit.