Energy monitors explained

  • What can energy monitors actually do?
  • How do energy monitors work?
  • Where can I buy an energy monitor?

It's easy to confuse energy monitors and smart meters, although they are actually very different devices. An energy monitor helps you to understand your electricity usage, whereas a smart meter sends information about your usage to your energy provider. 

This guide will help you understand more about energy monitors and what they can do.

Energy monitors – what do they do?

Energy monitors are simple handheld or tabletop gadgets that give you a real-time estimate of the amount of electricity you are using.

They are also known as home energy monitors, electricity monitors and electricity usage monitors. Widely available, they cost around £40 (or free from some energy suppliers) and you can install them yourself.

Most energy monitors enable you to view your real-time electricity usage in units of energy used (kWh), cost or carbon emissions. Some have additional features, such as allowing you to set daily electricity usage targets or alarms to alert you when you have used a set amount of electricity.

Energy monitors are designed to help you keep track of your electricity usage, discover how using different appliances affects your energy bills and, ideally, help you to cut your electricity consumption.

In our tests we've found that some energy monitors are better than others at accurately and consistently displaying information in a useful way. Take a look at our energy monitor reviews to find the best one.

Energy monitors – what don’t they do?

Energy monitors don't send information to your energy supplier, although many people mistakenly believe that they do.

Most energy monitors do not measure your gas usage, although the Saveometer from Eco1 Limited (launched in March 2011) does promise to show your gas usage if you buy the additional gas transmitter. We haven't tested the gas transmitter, but you can see how the main electricity monitor scored in our tests by visiting our Saveometer review. 

Energy monitors can't send information directly to your energy supplier. In fact, only smart meters can do this – see What is a smart meter? to find out more.

The EDF energy kit

Most energy monitors are made up of three parts: a handheld display, a transmitter and a sensor

How do energy monitors work?

Most energy monitors are made up of three parts: a sensor, a transmitter and a handheld display.

The sensor clips on to a power cable connected to your electricity meter box. This monitors the magnetic field around the power cable to measure the electrical current passing through it (in amps).

Once you’ve attached the transmitter to the sensor, it will send the information wirelessly to the handheld visual display unit, where it will be re-calculated and displayed as real-time power usage (in kWh), cost (£) and greenhouse gas emissions (tonnes of CO2).

Where can I get an energy monitor?

You can buy energy monitors from many high street shops and websites – including Argos, John Lewis, Tesco and Amazon – and there are several well-known energy monitor brands, such as Owl and Efergy. Different products offer different levels of functionality, and vary in price from around £20 to £100.

We’ve tested several energy monitors, and rated them for accuracy and ease of use - we've found that you don't have to spend a lot to get a Best Buy. Find out which energy monitors we rate as Best Buys in our energy monitors review.

Free energy monitors

You can also get a free energy monitor if you sign up to certain energy tariffs, such as British Gas’s EnergySmart tariff or Southern Electric’s Iplan tariff.

However, before switching to an energy tariff to get a freebie, make sure you’ve carefully weighed up the value of the freebie against the cost of the tariff.

In some cases you may be better off switching to a cheaper energy tariff, and buying an energy monitor separately. You can find the cheapest energy tariffs available to you by entering your postcode and a few simple details into the energy tariff calculator at Which? Switch - the average saving is around £250 a year.

More on this...

  • Read our energy monitor FAQs
  • Watch our energy monitor and smart meter video guide
  • Reviewed and rated: the latest energy monitor Best Buys