STRANGE though it seems, a typical microwave oven consumes more electricity powering its digital clock than it does heating food. For while heating food requires more than 100 times as much power as running the clock, most microwave ovens stand idle—in “standby” mode—more than 99% of the time. And they are not alone: many other devices, such as televisions, DVD players, stereos and computers also spend much of their lives in standby mode, collectively consuming a huge amount of energy. Moves are being made around the world to reduce this unnecessary power consumption, called “standby power”.

As in many other areas of environmental policy, the state of California is leading the way. On January 1st the California Energy Commission introduced mandatory standby requirements for various electronic devices—the first such obligatory regulations in the world. This is due in no small part to the efforts of Alan Meier, a staff scientist at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California. In the 1990s he noticed a proliferation in the number of household appliances that are never fully switched off, but spend most of the time in a standby mode, ready to spring into action when needed. The convenience of being able to switch on your television from the sofa using a remote control, in short, has a cost, since some circuits in the television must remain active, watching for signals from the remote control. Added up on a nationwide or global scale, Dr Meier realised, the wasted energy must be staggering. “We're moving from an electromechanical world that's on and off to an electronic world that's never off,” he says.

He and his colleagues at LBNL set out to quantify the scale of the problem. In 1998 they released an initial study which estimated that standby power accounted for approximately 5% of total residential electricity consumption in America, “adding up to more than $3 billion in annual energy costs”. According to America's Department of Energy, national residential electricity consumption in 2004 was 1.29 billion megawatt hours (MWh)—5% of which is 64m MWh. The wasted energy, in other words, is equivalent to the output of 18 typical power stations.

This figure, however, was based on estimates. So Dr Meier and his team went on to measure standby-power consumption directly, in an empirical study. Their results, published in 2000, revealed that standby power accounted for as much as 10% of household power-consumption in some cases. That same year, a similar study in France found that standby power accounted for 7% of total residential consumption. Further studies have since come to similar conclusions in other developed countries, including the Netherlands, Australia and Japan. Some estimates put the proportion of consumption due to standby power as high as 13%.

J.P. Ross, who took part in the 2000 study while a graduate student at the University of California in Berkeley, was particularly surprised by the variation in standby-power consumption between similar devices (see chart). “One television that I looked at had a minuscule amount, and one had a high standby load,” he says. This shows, he says, that “you can still have the functionality without the electricity loss.” The problem, as Dr Meier noted way back in 1998, is that there is very little incentive for manufacturers to make devices with low standby-power consumption. And even when they do, there is no easy way for consumers to distinguish between power-hungry devices and more abstemious ones.

Dr Meier and other researchers argue that there is no technical reason why all electronic devices cannot use the more efficient electrical designs with lower standby-power losses—and thus allow consumers to minimise consumption while maintaining convenience. The worst offenders consume more than 20 watts in standby mode. But nearly all standby functions, Dr Meier insists, can be performed with a power consumption on standby of one watt or less. Using the most efficient designs could reduce average household standby-power consumption by 72%, he calculates. Applying this reduction across the developed nations of the OECD would reduce carbon-dioxide emissions by nearly 0.5%—“equivalent to removing more than 18m cars from European roads,” he notes.

Sticks and carrots

So what can be done about the “electronic vampires” that are needlessly consuming so much power? Alas, there is little scope for reducing the inefficiency of existing household appliances, such as microwave ovens—other than switching them off at the mains or unplugging them when not in use, of course. Modifying them to reduce their power consumption is, in most cases, impractical.

A growing proportion of new household devices, however, contain newer, more efficient power supplies. Unlike old-fashioned, chunky power supplies, which contain iron cores surrounded by windings of copper wire, these new power supplies use “switch mode” technology to convert mains electricity to the low voltages used to power small devices. As well as being far more efficient, this can, with the addition of extra circuitry, reduce consumption to a fraction of a watt in both standby mode and “no load” mode (when a power supply is plugged in, but nothing is attached to it).

Power Integrations, based in San Jose, California, provides components for switch-mode power supplies to equipment-makers including Apple, Dell, Motorola, Samsung and Sony. Its president, Balu Balakrishnan, says his firm's components can be found in more than 1 billion devices worldwide. But, he says, switch-mode devices made by his firm and its rivals account for only 20% of the estimated 4 billion power supplies sold worldwide each year. The vast majority are still of the old, inefficient kind, which are cheaper. Equipment-makers do not have any incentive to use more efficient components, after all, since the cost (in higher power consumption) is borne by their customers.

That is why regulators around the world have started to introduce rules designed to encourage manufacturers to make their products less power-hungry. Most of these rules are voluntary: examples include the international Energy Star programme, the European Union's codes of conduct agreed with electronics manufacturers, and the standards laid down by the Australian Greenhouse Office. Of these, by far the best known is the Energy Star scheme, which began in America in 1992 and has since expanded to many other countries. Devices that meet particular standards for energy efficiency are allowed to display a special logo. In 2005 the scheme was extended to external power adapters, which can earn Energy Star approval if they consume less than 0.75W in “no load” mode.

In 1999 the International Energy Agency, based in Paris, adopted Dr Meier's proposed “one-watt” standard as a target for standby consumption. In 2000 Australia became the only country to adopt this standard nationally, in the form of a voluntary scheme that began in 2002. The aim is for most new products to meet the one-watt standard by 2012.

“It is now illegal in California to sell a television that consumes over three watts in standby mode.”

In addition to these various voluntary schemes, there have been some mandatory measures. Perhaps surprisingly, one of them was introduced by President George Bush, as a result of the California energy crisis of 2001. That year, Mr Bush issued Executive Order 13221, which states that every government agency, “when it purchases commercially available, off-the-shelf products that use external standby power devices, or that contain an internal standby power function, shall purchase products that use no more than one watt in their standby power consuming mode.” Given that Mr Bush is not renowned for his environmental credentials, this came as quite a surprise to those in the industry.

In late 2004 the California Energy Commission went even further by imposing limits on standby power-consumption for various consumer-electronic devices, including DVD players, external power adapters and stereos. This legislation took effect in January, so that it is now illegal in California to sell a television or DVD player that consumes more than three watts in standby mode. Power adapters will be limited to a standby consumption of 0.75W from next year, falling to 0.5W from January 2008. And new limits will apply to stereos and set-top boxes.

Not everyone approves. The Consumer Electronics Association (CEA), an American industry body, argues that the voluntary Energy Star scheme was working well enough already. Douglas Johnson, the CEA's senior policy director, says Alan Meier's one-watt standard is “more of a sound bite than a reasonable policy when it comes to the electronics industry”. Imposing mandatory regulation will stifle innovation and limit consumer choice, he warns. “Industry-led standards are a much better approach for focusing on energy-related efficiency than standards set by government,” he says. Last month the CEA succeeded in having some of the new rules slightly delayed.

But if California's new mandatory rules are a success, they could prompt other regulators to follow suit. In Australia, for example, regulators have always left open the option of applying mandatory standards to devices that consume “excessive” amounts of standby power.

Reducing unnecessary power consumption is not just a matter for device-makers and regulators, however. Consumers can do their bit too, by unplugging infrequently used devices or switching them off at the mains; looking for energy-efficiency logos and modern, efficient power supplies when buying new equipment; and unplugging chargers and power supplies when they are not in use. Even these simple measures are better than just standing idly by.