Home energy monitors: what are they, and how can they reduce my energy bills?

22 February 2021 | Aimee Tweedale

As the old saying goes: knowledge is power. And when it comes to saving power, the more you know about your energy use, the better!

That’s why energy monitors are so useful. They help you keep track of how much energy you’re using at home, and exactly where it’s all going. If you want to make savings on your electricity bills, and cut your carbon footprint, energy monitoring is a good first step. 

How an energy monitor could save you money on your bills

Wondering how to get an energy monitor, how it works, or whether you should bother if you already have a smart meter?

We’ve got you covered. Keep reading to have all your energy monitor questions answered.

What is an energy monitor?

An energy monitor is a device that helps you track how much energy you’re using at home. 

The energy monitoring system is usually made up of these units:

  1. A sensor that clips onto a power cable connected to your electricity meter. This is the part that actually measures your electricity use.
  2. A small handheld device with a screen that shows you how much electricity you’re using, usually in kilowatt hours (or kWh). Some models will connect to your computer or smartphone, so you can look at the information there.
  3. Some models might also have a transmitter – this sends the information wirelessly to the handheld device, so you can read it on the screen.

What is a plug-in monitor?

A plug-in energy monitor is a little gadget that you can directly plug into the mains. You can then plug your appliances into it, and the screen will tell you how much energy the appliances are using. 

How do energy monitors work?

The sensor is the part of the energy monitor that figures out how much electricity is being used. Usually, you’ll have to attach the sensor on, or near your electricity meter.

It works its magic by picking up on the magnetic field that’s created around your main cable. The bigger the current created by the field (aka, how much the magnetic field is moving around), the more electricity you’re using. 

Your clever energy monitor will take this information from the sensor, and then convert it into kWh. Some models will also show you how much it’s costing in pounds and pence, in real time. 

Woman using an energy monitor at home

Home energy monitors vs smart meters: what’s the difference?

Here in the UK, the government is aiming to get smart meters fitted in as many homes as possible by mid-2021. Chances are, you may have one installed already. If that’s the case, do you need an energy monitor too?

The crucial difference between smart meters and energy monitors is:

  • Energy monitors are just for you. They give you the facts and figures you need to work out where you’re using the most energy in your home, and how to save money. They won’t directly affect your bills. 
  • Smart meters are for you and your energy supplier. They are electricity and gas meters that, unlike your old traditional meter, can send readings directly to your energy supplier. Your energy company can then use that info to give you more accurate bills.

Some people might find it useful to have both, but you may find that you can get all the information you need from your smart meter. Find out more about how to get a smart meter of your own, and how to use the In-Home Display it comes with.

Does my home energy monitor send information to my energy supplier?

No. Only smart meters can communicate with your energy supplier. Energy monitors are for your eyes only.

Smart meters don’t share any details with your energy supplier, such as how long you’ve been watching TV! They only share meter readings, telling the energy company how much energy you’ve used overall. This helps make your bills more accurate, and puts you in control. You can change the settings on your meter, to send readings as often as you’d like.

At OVO, we recommend getting a smart meter rather than an energy monitor. It saves you money, and the effort of sending us regular meter readings. Not to mention, they help you cut down on your carbon footprint.

Should I get a home energy monitor?

Benefits of home energy monitors

  • Electricity monitors give you the information that you need to make your home more energy-efficient
  • Those changes could save you money. According to the Energy Saving Trust, having an energy monitor could knock as much as 15% off your annual electricity bills1.
  • It could also help you lower your carbon footprint, as you become more aware of which appliances in your household are guzzling the most electricity.

Disadvantages of home energy monitors

  • Handy as they are, energy monitors sadly won’t make savings on their own. They just give you information about your energy use. It’s how you use that information, and the changes you make to your lifestyle, that will affect your bills.
  • They’re not always as accurate as smart meters. This is because they collect data via a sensor, not directly from the meter itself. (More on this below.)
  • Unlike a smart meter, an energy monitor won’t automatically send your data to your energy supplier. So, if you don’t have a smart meter, you’ll still have to send meter readings yourself. 

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Are home energy monitors completely accurate?

Some monitors are more accurate than others. For the best results, keep the following in mind when you choose an energy monitor:

  • You’ll need a monitor that measures ‘actual’ power, shown in Watts, not ‘apparent’ power, measured in volt-amps. Apparent power monitors are not so good at picking up on small amounts of energy.
  • This will also help you work out how much you could save, as your energy supplier will charge you for power used in kWh. Find out more about kilowatt hours here.
  • If you want to find out how much power specific appliances are using, your best bet is a plug-in monitor.

But the most accurate option overall is a smart meter – that’s why we at OVO recommend you get one.

How would an energy monitor help me reduce my energy use?

Energy monitors give you information. They don’t make changes to your energy use – that part is down to you.

Your energy usage monitor will show you how much energy you’re consuming. It might also show you how much that energy costs, and the impact it’s having on the environment. If you have a plug-in monitor, you’ll even be able to take a look at the energy use of specific appliances – which should help you figure out exactly where your biggest energy waste is happening.

Some models allow you to set daily electricity use targets, or set alarms, to let you know when you’ve reached a certain level of use.

You can use all of this data to help you make changes to the efficiency of your home. Find out more about what energy-efficiency is and why it matters, in our complete guide.

How much money could a home energy monitor save me?

As we shared above, the Energy Saving Trust found in small trials that energy monitors could save households 5-15% on their annual bills.

Exactly how much you save will be up to you, and what changes you decide to make at home. For example, you could save as much as £35 a year just by remembering not to leave your appliances on standby2!

Keep reading to find some more suggestions, or check out our guide to reducing your gas and electricity bills.

Couple using smart technology to monitor their home energy use

How to install an energy monitor

You don’t need to be a qualified electrician to install an energy monitor. Most models are fairly straightforward. 

Just attach the sensor unit to your electricity meter. Then, you’ll need to tune the transmitter and the handheld unit so that they can ‘talk’ to each other. Your monitor should come with instructions that tell you how to do this. 

How should I start using my home energy monitor?

First, switch off all the electrical things you can – though probably not the fridge and freezer! Then walk around each room holding your energy monitor, and switch things back on as you go.

Within a few seconds, you should see the monitor reading increase when you switch on new appliances. It’s a great way to find out which appliances or rooms are costing you the most. Some of your discoveries could be quite a shock!

Write down what you’re finding out, so you can use the information to help you make cost-cutting decisions. 

Interested in learning more about which appliances in your home are the greediest when it comes to energy? Read our complete guide to how much electricity the average home uses.

Which energy monitor should I get?

What kind of energy monitor you get will depend on your needs. There are 3 main types:

  • A handheld monitor will come with a sensor and a handheld display unit. These are good for sensing the energy use of your whole home.
  • An online monitor is basically the same, but instead of a handheld unit, you’ll be able to show the data on your phone or tablet screen. 
  • A plug-in monitor can be plugged directly into the mains, and used to measure the energy use of individual appliances.

How much do home energy monitors cost?

Energy monitors can be pretty inexpensive. You can find basic models for around £25-30. But of course, you get what you pay for – some of the most highly recommended models, which can tell you more about your energy use, go up to around £150. It’s worth shopping around.

Do some energy companies offer free energy monitors?

It’s unlikely that your supplier will offer a free energy monitor.

We don’t offer free energy monitors at OVO, because we believe our smart meters, with their In-Home Displays, offer the same information, but with extra benefits. So if you’re an OVO customer and you want to monitor your energy use, just get in touch to ask us if you can upgrade to a smart meter.

If you’re not yet an OVO member, why not switch today, and start saving on your energy bills?

Our Better Smart tariff offers 100% renewable electricity3 at a competitive rate. It also comes with a free smart meter installation, helping you monitor your energy and keep costs down. Get a quote in less than 2 minutes, to find out how much you could save.

How can I reduce the amount of energy I use?

Has this article inspired you to kickstart your energy-efficiency journey? Here are 6 top tips for saving electricity (and money) around the home.

  1. Turn appliances off at the wall. Leaving them on standby is more costly than you think!
  2. Use energy-saving light bulbs. As well as turning lights off when you leave a room, you could also save a few quid by replacing the bulbs. Did you know that only 10% of the energy used by traditional light bulbs is actually used to create light? The rest is wasted as heat!
  3. Draught-proof your home. Here’s our guide to how to do it on a budget.
  4. Say goodbye to your old boiler. If you’ve had your boiler for more than 15 years, it might be time to upgrade to a more efficient model.
  5. Take shorter showers, and don’t leave the taps running. Water heating is a surprisingly large source of energy use in your home.
  6. Be cool (by using cooler settings). Try to keep your washing machine and dishwasher running under 30˚, and always fill them for each cycle. There’s no point doing things by halves!

Get smart with OVO

If you’re interested in making your home more energy-efficient, we can help you get set up with a smart meter, free of charge. Find out all about our smart meters here.

We’ve also teamed up with tado° to give our members the chance to buy a smart thermostat directly through us. Smart thermostats can help you control your home heating no matter where you are, from your phone or tablet. 

Not an OVO member yet? Get a quote in less than 2 minutes, to find out how much you could save by joining us. All OVO members get:

  • 100% renewable electricity as standard
  • A tree planted in your name for every year you’re with us4
  • 3-5% Interest Rewards when your account is in credit5 
  • A £50 gift card every time you introduce a friend to us

Sources and references:



3  The renewable electricity we sell is backed by renewable certificates (Renewable Energy Guarantee of Origin certificates (REGOs)). See here for details on REGO certificates and how these work.  

4 Each year, OVO plants 1 tree for every member in partnership with the Woodland Trust. Trees absorb carbon dioxide from the atmosphere, so tree-planting helps to slow down climate change.

5 Interest Rewards are paid on credit balances of customers paying by monthly Direct Debit. It is calculated at 3% in your first year, 4% in your second year and 5% in your third year (and every year thereafter) if you pay by Direct Debit.

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