Energy monitors

Looking for ways to reduce your electricity bills? Keeping track of your consumption is a good first step. Home energy monitors are designed to help with this, by tracking your electrical appliances so that you can make more informed decisions about their use. Read on to discover more about them, and how they differ from monitors provided with smart meters.

Share this guide
Close-up of energy monitor display

In this guide:

  • What is an electricity consumption monitor?

  • How does an energy monitor work?

  • Electricity monitors vs. smart meters

  • Can an energy monitor save you money?

  • Saving money on energy 

  • How to measure electricity usage by an appliance 

  • How accurate are energy monitors?

  • How much do energy monitors cost?

  • How to choose an energy monitor

What is an electricity consumption monitor?

Electricity consumption monitors, or energy monitors, are small devices about the size of a mobile phone. They show you how much energy is used in the home, along with how much it’s costing you. Armed with this information, you can adjust household consumption to potentially save money and energy.  

Electricity consumption is displayed in kilowatt hours (kWh), which is the same unit shown on your electricity bills. This helps you keep track of your consumption for billing purposes. You’ll see the immediate effect on your energy monitor from any electricity used within the home, whether it’s turning the kitchen lights on or leaving your TV in standby mode. 

How does an energy monitor work?

Energy monitors consist of two main parts:

  • Sensor

A sensor clips onto your electricity meter’s power cable. This measures the electricity as it passes through the cable, transmitting it to a visual display unit. 

  • Monitor

The visual device converts the usage in kWh to the cost of your electricity in pounds and pence. You’ll see a clear breakdown of where you’re using energy in the household, so that you can make necessary changes to cut bills. 

Some energy monitors forego the handheld visual display unit in favour of an online display instead. These work with a sensor as described above, but instead of looking at the handheld unit, you can log in to an account to view the information from any online device, including your mobile.

There are basic plug-in electricity monitors as well, with the sensor embedded in the monitor itself. These simply plug into the wall socket to measure the energy used by individual devices, rather than the whole home. 

Electricity monitors vs. smart meters

A smart meter also monitors your electricity consumption with a visual display unit, so how is it different to an electricity monitor? Although they can be used in a similar way, there are a few key differences.

Smart meters submit your usage data directly to the energy supplier, but energy monitors are strictly for your own information. They are meant to complement the meter, not replace it. Smart meters accurately measure your gas and electricity usage, submitting them to the supplier so that you don’t have to provide meter readings. They’re in the process of being rolled out across the country, with the aim of replacing traditional gas and electricity meters in most households by June 2021.

Energy monitors simply calculate the usage so that you can see where you’re consuming electricity within the home. By breaking it down into kWh and cost, you can then use this information to change your habits or even switch suppliers if the cost is too high. 

Can an energy monitor save me money?

Simply installing an energy monitor won’t automatically save you money. However, it’s a useful tool that makes you more aware of how much energy you’re using, and which appliances are costing the most to run. By changing your behaviour, you can then cut your electricity and gas bills. 

For example, leaving appliances in standby mode might be costing you more money than you think. By seeing the financial impact of leaving lights switched on, you’ll be reminded in real-time to switch them off when you leave the room. You can also see if an older washing machine or dishwasher is due for replacement with a more energy efficient model.  

Saving money on energy 

All these small actions add up to help reduce the bill for many households. In fact, the Energy Saving Trust estimates that your electricity usage drops by 2.8% on average when using an energy monitor, although this depends on your behaviour once you’ve started monitoring your consumption. You can easily enjoy a much bigger saving by looking for additional ways to make your home efficient.

While using an energy monitor is a great way to save a few pounds on your monthly bills, it’s also one of several tools to help you create a more energy efficient home overall. Adequate insulation, draught proofing, and replacing outdated models with more efficient appliances are all ways that will help reduce your energy consumption.

How to measure electricity usage by an appliance 

Home energy costs are calculated in kWh, or kilowatts per hour. Depending on your energy tariff, you’ll be charged a set amount for each kWh: the equivalent of using 1000 watts for one hour.

If you want to see how much a single appliance is using, a plug-in energy monitor is the easiest way. These units simply plug into the wall socket and provide a pass-through socket into which you plug your appliance. It’ll then show you figures like:

  • Voltage 

  • Power consumption of the appliance (measured in watts)

  • The length of time the appliance has been drawing power

  • Electrical current drawn by the appliance

  • Total consumption in kWh

  • Cost of running the appliance

Individual monitors provide more accurate readings for individual appliances than regular energy monitors – or ‘whole home monitors’ as they’re sometimes known – as we’ll see below.

How accurate are energy monitors?

Although electricity usage monitors provide a general overview of how much power you’re consuming, some won’t always be that accurate when consumption levels fall below 60 watts. To work out the power used by an individual appliance, you must measure the household consumption first with the device switched on, and then again with it switched off. There is some room for small errors in this type of calculation, though it gives you a general sense of the appliance’s consumption.

Whole home monitors are advantageous because they cover other types of appliances that don’t use plugs, like immersion heaters, central heating pumps, cookers, and electric showers. These types of devices can’t be measured with a plug-in monitor. 

The most accurate whole home energy monitors will display the actual power used, in watts, rather than the apparent power in volt-amps. This is because apparent power is less accurate with smaller amounts of consumption. Plus, your provider charges you in kilowatt-hours, which is why it’s better to see your consumption in watts for the sake of both accuracy and making a meaningful comparison.

How much do energy monitors cost?

Some energy suppliers supply energy monitors for free. However, this type of device is relatively inexpensive with a price range varying between £25 and £100. There are many different models to choose from, each with their own features. 

One thing to note is that a free energy monitor shouldn’t be your primary concern when choosing a supplier. Be sure to take all the other factors into account as well when making an energy switch, including tariffs, types of energy, customer service and reputation. 

How to choose an energy monitor

Energy monitors vary in both cost and function, so it’s worth comparing what’s out there to find the best fit for your home. A few key features to be on the lookout for include:

  • Wireless connectivity

  • A portable LED display unit

  • Historical data to track your consumption over time

  • The ability to set different tariffs at different times of day for those with Economy 7 meters

  • Daily electricity usage targets 

  • Usage alerts when you have exceeded these targets

You should also think about whether you want to be able to measure energy consumption throughout the household, or simply monitor a few appliances. This can help you make a choice between whole-home and plug-in models. Some are designed to do both as part of a larger system.

Last updated: 21 December 2020