If you want to save electricity (and why wouldn’t you?) it helps to focus on the things that use the most, and so cost you most money.
Some electrical items use a lot of electricity. Others don’t. As a rule, those with moving parts or which produce heat use much more than those that produce light or sound. So if you want to save electricity and money, there’s no point worrying about a digital clock or an electric razor since these use so little power you would hardly notice the difference. The big savings lie elsewhere.
Every electrical appliance has a power rating which tells you how much electricity it needs to work.
This is usually given in watts (W) or kilowatts (kW) (1000W = 1kW). Of course, the amount of electricity it uses depends on how long it’s on for, and this is measured in kilowatt-hours (kWh).
An item like a fridge has a low wattage, but because it’s on all the time it’ll use a lot of electricity. And although an iron is only used now and again, it uses a lot of electricity so the quicker you do your ironing the better.
See table below for ratings for different appliances.
Electricity is sold by the kilowatt-hour (kWh) – usually referred to as ‘units’ on your electricity bill. We’ve done some of the work for you, but if you’re feeling mathematical you can work out how much your own appliances cost to run by multiplying their wattage by the amount of time they’re on and then by the cost of electricity per kWh. So let’s say you have a 500W (0.5 kW) dehumidifier and you run it for a whole day (24 hours). It will use 12kWh of electricity (e.g. half a kilowatt every hour). If your electricity costs 15p per unit, then multiply 12kWh by 15p and you get a grand total of 180p, or £1.80. This is what it costs to run the dehumidifier all day, and you can see how appliances can add a lot to your bills.
But (and sorry if this is complicated) sometimes a higher-wattage appliance will actually use less power overall than a lower-wattage one. This is because it is well designed and does its job quicker. An energy efficient dish washer, for example, may have a power rating of 2kW – the same (or higher) as a non-energy efficient one. But what makes it energy efficient is that it completes its cycle quicker. So while it may use the same (or more) electricity per hour, it’s working for less time so uses less energy overall. In other words, don’t judge the energy efficiency of a device only by its given power rating, particularly if it is controlled with thermostat or operates on a timed cycle.
Instead, if you’re buying a new fridge or TV or other appliance, the best way to judge its energy efficiency is the label. Those rated ‘A’ or above are the most efficient for their size. To compare between differently sized appliances, energy labels also now print suggested kWh usage per annum for each appliance.
To compare between differently sized appliances, energy labels also now print suggested kWh usage per annum for each appliance.
|Appliance||Average power rating (Watts)||Cost to use per hour (pence)*||Cost to use per 10 mins (pence)*|
|TV box||30-40||0.5–0.6||~ 0.1|
|Smart phone (charge)||2.5-5.0||<0.1||<0.1|
*All calculations are based on an assumed unit rate of £0.15p per kWh and rounded up or down to the nearest 0.5p or 0.1p as appropriate
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These are are wireless devices that can tell you useful things like what your current energy use is costing you. The display can show much electricity is being used at that moment, as well as how much was used last week or last month. Your energy supplier should provide an energy monitor (also called in-home display) if you have a smart meter, or you can by a separate energy monitor.
Content for this page is supplied by and with the permission of our partners, Centre for Sustainable Energy. Similar content and more can be found at https://www.cse.org.uk/