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Up to about 30 years ago, when you went on holiday all you had to do was unplug the fridge and the electricity meter would stop completely. Nowadays the meter will continue to spin unless you switch off the electricity at the mains, because of the ever increasing number of appliances which constantly gobble energy even when they are not on.

Videos, televisions, microwaves, computers and printers, cordless phones and answer phones only stop consuming electricity if they are unplugged, which never happens, either for the sake of convenience or because the devices need to stay plugged in to maintain standby functions like clocks, calendars and memory, or so they can be switched on by remote control.

Audio and video machines were the first to use standby energy. Then came the timer screens on cookers and microwaves, and nowadays a host of other products need a constant supply of electricity.

To find out which appliances are wasting energy and money while you sleep is in many cases relatively easy: just turn out the lights and see how many pilot lights or digital screens are blinking at you in the dark. If the appliance has no light or other telltale sign then tracking down these energy wasters is a little more complicated, but not impossible. If a device has a remote control, takes its energy through a transformer or functions as a transformer itself, if it has touch sensors, is warm when switched off or has no off button, you can be sure that it uses standby energy.

Although the consumption of each appliance may be only a few watts - according to the Organisation of Consumers and Users (in their magazine Compra Maestra 246, February 2001), having your video on 24 hours a day costs just over 4 euros - the energy wasted by these domestic appliances has become a problem of planet-wide proportions. Because itï¿½s a constant trickle of energy and because there are ever more appliances which work in this way: in middle class homes there are an average of more than 15 devices of this type, which means each household is wasting 60 watts of electricity for appliances to do nothing, or at least not to do the job they were bought for.

According to the IEA it is vital to put a brake on this consumption of standby electricity because the amount will presumably rise with the increasing number of electronic devices and the growing tendency to network devices in homes and offices. Intelligent houses will require fridges and dishwashers, for example, to be on permanent standby so as to be able to communicate with computers and mobile telephones.

Unplugging appliances when they are not in use would seem to be the easiest solution to the problem, but in many cases this would mean they would lose some of their functions. However manufacturers do have a permanent solution at hand, because nowadays it is technically feasible for a device to use no more than one watt in standby mode. According to the IEA, if all appliances were manufactured using energy saving criteria, ï¿½standby consumption would be reduced by 70%, which would account for about 4% of the difference between CO2 emissions forecast by the Organisation for Economic Cooperation and Development (OECD) and Kyoto protocol targetsï¿½. And all that at a relatively low cost and without affecting either the way the appliance works or its safety.

ï¿½ A study by the IEA reveals that the standby power of all the electrical appliances in the nearly 15 million Spanish homes is in the order of 299 megawatts, which is equivalent to an annual consumption of 2.6 terawatt-hours, or 1.6% of all Spainï¿½s electricity consumption.

ï¿½ Among the appliances which use most power on standby are transformers (15.7 watts), DVDs (15W), videos (12W), ovens (14.5W), induction hobs (13.2W), TV decoders (11W), cordless phones (8.7W), PC monitors (6.9W), modems (7.1W), televisions (6.4W), answerphones (4.6W) and battery chargers (5.1W).

ï¿½ According to a recent study in the USA (Rosen and Meier 2000), videos consume more electricity in standby mode than when they are playing back or recording. And more than 40% of microwaves use more electricity to power the clock and screen than to cook the food we eat (EECA 1999).