The amount of energy used by each appliance depends on how much power it draws when in operation and how much of the time it is used.
The power usage is measured in watts and kilowatts (a kilowatt =1000 watts), and the amount of energy that it consumes in watt-hours or kilowatt hours (kWh).
A single bar electric fire often uses electricity at the rate of one kilowatt (kW) per hour. So, in an hour an electric fire will use one kilowatt hour (kWh). One kilowatt hour is also referred to as a ‘unit’ of electricity. In 2010 this cost an average of around 13p.
This table shows how various energy-using devices in the home compare — the amounts obviously vary according to how energy efficient your appliances are and how often you use them, but this should give you an indication.
Appliance Annual estimates (2010)
Uses/ hours kW per use/ hour Total kWh Total cost (£)1
30 year old fridge freezer 8760 0.14 1209 £160
Standard 60W bulbs (4 @ 6hrs/day) 8760 0.06 526 £69
Fridge-freezer A2 8760 0.05 412 £54
Tumble dryer 148 2.50 370 £49
Electric hob 424 0.71 301 £40
Electric oven 135 1.56 211 £28
Fridge Freezer A++ 8760 0.02 206 £27
Kettle 1542 0.11 170 £22
Washing machine 187 0.63 118 £16
Dishwasher (55°C) 110 1.07 118 £16
Low energy 11W bulbs (4 @ 6hrs/day) 8760 0.01 96 £13
Microwave oven 96 0.95 91 £12
2 Usage rates and energy consumption adapted from carbonfootprint.com. Note addition of 30yo fridge (t2c) and lightbulbs (OG)
This table highlights the high energy cost of appliances that are kept plugged in and run 24 hours a day throughout the year and the huge savings that can be made.
The difference between the cost of running a 30 year old and a fairly standard modern ‘A’ rated freezer is £106/year. A super-efficient A++ rated fridge freezer would save £133/year at 2010 electricity prices.