Don’t waste electricity!

The number of electric appliances we have at home is increasing all the time. They all consume power when we use them. But some also use electricity when they are not in use. Multiply all these small ‘leaks’ by the number of homes and an enormous amount of power is wasted. If you organise the way you plug appliances in and change certain habits you can reduce this waste without inconvenience.

In a normal home you can find around twenty appliances that consume power when you aren’t using them. The International Energy Agency estimates that this ‘hidden’ consumption may account for 5-10% of all household power consumption.[1] In the first table you can see what types of appliance consume power in this way and why.The power consumed per appliance is very little, but, as there are so many, the total is considerable. Some examples can be seen in the second table. As you can see, in some cases the total consumed while they are not being used is much more than the power consumed when we are using them! Technological advances have led to gradual reductions in power consumption when the appliance is in standby mode or simply plugged in, thanks to more efficient power packs and memory units (for example, today’s mobile phone chargers use less power than earlier models when they are plugged in but not being used). But we are also seeing power consumption in appliances that used not to consume power when they were simply plugged in. For example, fridges may now use power when the motor is not running because they incorporate temperature displays.

If we take just the appliances in the table and assume that they are used for the number of hours shown in the Use column in each home (in Mediterranean European countries), we find that total consumption while we are not using them is 2,512,907,629 kWh per year. This is equivalent to 4.5% of the power generated by Spain’s six nuclear power plants.[2]

Identifying hidden power consumption

We give some general rules here but technological developments may bring about changes. The best thing is to get information about each appliance in shops or from manuals.

Behaviour Why? Examples
Does not use power when plugged in Does not need to transform mains power and does not use memory Small ‘non-intelligent’ electric appliances: food mixer, juice extractor, toaster, hair dryer, heater, etc.
Uses power when plugged in Uses voltage other than 220V (needs transformer) or uses DC (needs power pack), keeps track of time, displays information, keeps pilot light on, etc. Computers, monitors, printers, routers, televisions, programmable appliances (video/DVD recorders, radio alarms), microwave ovens, electric cookers, mobile phone chargers (especially wider models, narrow models consume negligible amounts), some halogen bulbs, etc.
Consumes on standby It is ‘awaiting orders’ All those activated with a remote control, mouse or keyboard

How much power do we use without realising it?

The power used by an appliance varies widely from one model to another and over time; these figures are examples of consumption for specific appliances. If you want figures for your own home or office you can install a meter between the plug and the appliance.

Appliance Power (W) Use (hours per day) Daily consumption (kWh) Unnecessary consumption / total consumption
In operation Standby Only plugged in
CRT television (not flat-screen) 45 3 0.002 4 h in use
20 h on standby
0.18
0.06
25%
DVD 10 9.6 4 2 h in use
22 h on standby
0.02
0.21
91%
Computer 53 5-50* 4.2 8 h in use
2 h on standby
14 h plugged in
0.42
0.05
0.06
20%
Printer 14 2.5 1.3 0.25 h in use
23.75 h plugged in
0.004
0.03
89%
Computer loudspeakers 2.5 1.4 4 h in use
20 h plugged in
0.01
0.03
74%
Flat screen 27 (medium brightness) 0.6 0.6 8 h in use
2 h on standby
14 h plugged in
0.22
0.001
0.008
4%
Router 9 2.3 8 h in use
16 h plugged in
0.07
0.04
35%

* Consumption varies a great deal depending on the standby mode. Calculations are based on consumption of 25 W.

Easy ways to save

The best way to prevent an appliance using electricity when you’re not using it is to cut off the power, i.e. unplug it. This is not the same as switching it off.

  • Start by looking at the appliances you have at home and pick out those that do not work properly if they are unplugged (see the Appliances you shouldn’t unplug table.) Decide which of these you really need to have permanently available.
  • Unplug appliances you decide you don’t need to keep permanently plugged in. Get into the habit of unplugging your phone charger when you disconnect the phone from the charger. To cut off the power supply to several appliances at once you can use a power strip fitted with a switch. It is important for the power strip to be easily accessible. If you put it on the far side under a table, you will find it inconvenient to crouch down and switch it off, making this simple, useful idea totally impractical. Disconnecting the power supply also helps to protect you against surges caused by storms or malfunctions in the grid.
  • Another way to disconnect various appliances at the same time is to turn off the mains circuit breaker. This is a particularly good solution in offices (and can save companies significant amounts of money). Beforehand you need to find out which plugs are connected to which circuit breakers.
  • Think about unplugging the appliances you keep permanently plugged in if you are going to be away for several days.
  • Avoid having appliances in standby mode as far as possible. This may involve walking as far as the appliance instead of pressing a button on the remote control (this is also good exercise!).
  • In the case of computers, it is worth reducing their power consumption if they are not to be used for some time. The most convenient and economical method is to use the ‘hibernate’ option. You only need to press a button to turn off your computer and press it again when you come back. In less than a minute you will restore all windows and open files exactly as you left them and in the meantime the computer will have been off (you can even unplug it). The extra power needed when you start up your computer is offset even if the computer is only in hibernate mode for a few minutes (this depends on each computer). That said, turning your computer on and off frequently is not good for it and neither is keeping it on for many hours. It’s a good idea to turn it off a couple of times each day (at lunch time and at night, for example).
  • Another option is to use the ‘sleep’ mode, which allows you to use less power during short periods of inactivity. To use it you need to disable the screen-saver. The names used to refer to the ‘hibernate’ and ‘sleep’ modes vary, and the way to use them depends on your operating system; check the configurations available to you.

Appliances you shouldn’t unplug

Appliances that use timers will lose the time setting if they are unplugged, unless they contain a battery (this is what happens when there is a power cut). Think carefully which appliances need to track the time. Some programmable devices (video and DVD recorders, alarm clocks, etc.) have a battery, which means the programming information is not lost if there is a power cut. They should be left plugged in because they will need power when the programmed operation takes place.

The base station of a cordless phone needs power all the time because it also acts as an antenna. Fridges are another appliance that should normally be kept plugged in.


[1] International Energy Agency: Standby Power Use and the IEA “1-Watt Plan”, 2007.

[2] Data for number of homes and nuclear power generation: National Statistics Institute and Ministry of Industry.