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Energy monitors explained

By Matthew Knight

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Energy monitors explained

Your essential guide to energy monitors. Including what they are, how they work and how you can use an energy monitor to save money.

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

Energy monitors are also known as home energy monitors, electricity monitors and electricity usage monitors. You can use the data from an energy monitor to keep on top of how much electricity you're using. This means you can also use one to cut your energy bills.

Widely available, they cost around £40 (or free from some energy suppliers) and you can install them yourself.

Here, we tell you all you need to know about energy monitors.

Want to cut your energy bills? Use our independent switching site, Which? Switch, to make sure you're on the cheapest energy tariff.

Energy monitors – what do they do?

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. 

To find out more about smart meters, go to our smart meters guide

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

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.

Energy monitors – what don’t they do?

Most energy monitors do not measure your gas usage. The Saveometer from Eco1 Limited (launched in March 2011) does promise to show your gas usage if you buy the additional gas transmitter. 

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

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. Then the data 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. To help you choose the right one for your home, find out how to buy the best energy monitor.

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Free energy monitors

You can get a free energy monitor if you sign up to certain energy tariffs - ask your energy provider for more information.

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.

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 our independent switching site, Which? Switch. Click to compare gas and electricity.