There are two kinds of energy monitors: whole house energy monitors, which are hand-held screens that you can take anywhere in your house. The monitor communicates with a small separate unit that clips onto your electricity meter and tells you how much electricity you're using in real time.
Online whole house energy monitors , like the one pictured above from Loop, work in the same way fundamentally, except that you simply log in to view the information from your preferred device — be it your smartphone, tablet or desktop/laptop.
Energy monitors are not a substitute for your existing energy meter, just a complement to it. Energy monitors shouldn't be confused with other types of meters such as smart meters or prepayment meters
Smart meters send information of your usage directly to your energy supplier — something energy monitors don't do. Smart meters can accurately monitor your gas and electricity usage remotely, so you don't need to provide meter readings, and your bills will be completely accurate. They are currently in the process of being rolled out as part of a nationwide scheme to assist households in understanding how much they are spending on energy and how to cut their usage accordingly.
Prepayment meters differ from normal meters because as well as showing a meter reading, they must be 'topped-up' with credit. They are often installed in homes that have fallen into debt with their energy supplier, and can help people to budget more effectively. They can be topped-up in a variety of ways, including smartcards, tokens, keys or even coins.
An energy monitor alone can't save you any energy - but it will make you aware of just how much energy you're using, so it's a great tool to help you change your behaviour and cut your gas and electricity bills. With energy monitors it can become clearer what the true effects are of leaving multiple appliances on stand-by, or having a change in circumstance such as people being at home more often.
According to the Energy Saving Trust you could find that your energy usage drops by between five and 15% in the first year of using an energy monitor, which could be a saving of £25 to £75 on a £500 bill.
It is possible to find free energy monitors - a few energy suppliers may offer them.
However, you should avoid choosing a tariff because of the free monitor on offer, as this might not be the cheapest option for you. Always shop around for the best energy tariffs as you can buy an energy monitor for anywhere between £30 and £100, and there are a range of different makes and models to choose from.
A more basic alternative to an energy monitor is a plug-in monitor. This is good for working out the power consumption of individual devices.
Plug-in meters (or plug-in energy monitors) are used between a socket and the plug of the device being measured. Some plug-in meters require a battery backup, but it's preferable to choose one that doesn't, otherwise you're at risk of losing data.
If a monitor only measures apparent power then it will be less accurate at lower consumption levels, at under 100 watts, and particularly under about 60 watts. (When you buy electricity, you are charged for actual power usage by the kilowatt-hour (kWh), that's the equivalent of using 1000 watts for an hour).
Whole home monitors are not as good at working out the power consumption of individual devices, as you have to measure overall consumption with a device turned on, and then measure it again with it switched off, which can be problematic.
The advantage of whole home monitors is that they can cover devices which do not have plugs, such as alarm systems, immersion heaters, lighting circuits, central heating pumps and controllers, showers, cookers, and other direct wired devices (although only in total).
Energy monitors vary considerably in terms of their features and how much they cost, so you might want to compare a few different models before you buy one. Some of the most convenient features and benefits of energy monitors include:
a display that shows your current energy use;
wireless connectivity, and a portable display so you can move it around your home;
being able to look at historical data including daily, weekly and monthly usage.
How much you want to pay for an energy monitor will depend on your individual circumstances, but it's good to remember that in most cases you are likely to make your money back if you try to reduce your energy usage as a result of buying an energy monitor.
Using an energy monitor is a great way to measure your current energy usage and may even encourage you to use less, but it's no substitute to making changes to your home and your own energy habits.
Before you consider an energy monitor you should make sure your home is already as energy-efficient as possible. Ensuring your home is adequately insulated is the first step. Make sure you have loft insulation in place and, even if you do, make sure you have the correct level installed by reading our loft insulation guide.
Even if you have sufficient insulation in place you should make sure your home is draught-proofed. Just check around doors and windows for any escaping heat. It's easy and cheap to draught-proof your home with materials you can pick up at your local DIY shop.