Standby power

In the past, standby power was primarily a non-issue for users, electricity providers, manufacturers, and government regulators.

By 2010, regulations were in place in most developed countries restricting standby power of devices sold to one watt (and half that from 2013).

[2] The term is often used more loosely for any device that continuously must use a small amount of power even when not active; for example, a telephone answering machine must be available at all times to receive calls, and switching off to save energy is not an option.

The U.S. Department of Energy said in 2008: "Many appliances continue to draw a small amount of power when they are switched off.

Although the power needed for functions such as displays, indicators, and remote control functions is relatively small, the large number of such devices and their continuous plugging in resulted in energy usage before the One Watt regulations of 8 to 22 percent of all appliance consumption in different countries, or 32 to 87 W. This was around 3–10 percent of total residential consumption.

[6] A similar study in France in 2000 found that standby power accounted for 7% of total residential consumption.

[7] In 2004, the California Energy Commission produced a report containing typical standby and operational power consumption for 280 household devices, including baby monitors and toothbrush chargers.

[8] In 2006, some electronics, such as microwaves, CRTs, and VHS players, used more standby power than appliances manufactured in the previous five years.

Devices such as security systems, fire alarms, and digital video recorders require continuous power to operate properly (though in the case of electric timers used to disconnect other devices on standby, they actually reduce total energy usage).

In July 2001 U.S. President George W. Bush signed an Executive Order directing federal agencies to "purchase products that use no more than one watt in their standby power consuming mode".

The regulations mandate that from 6 January 2010, "off mode" and standby power for electrical and electronic household and office equipment shall not exceed 1W, and "standby plus" power (providing information or status display in addition to possible reactivation function) shall not exceed 2W.

Other devices consume standby power required for normal functioning that cannot be saved by switching off when not used.

[24] Errors of measurement at the low standby powers used from about 2010 (i.e., less than a few watts) may be a very large percentage of the actual value—accuracy is poor.

[23] Modification of such meters to read standby power has been described and discussed in detail (with oscilloscope waveforms and measurements).

[25] Essentially, the meter's shunt resistor, used to generate a voltage proportional to load current, is replaced by one of value typically 100 times larger, with protective diodes.

They are often subject to other errors due to their mode of operation: Laboratory-grade equipment designed for low power measurement, which costs from several hundreds of US dollars and is much larger than simple domestic meters, can measure power down to very low values without any of these effects.

Standby power consumption can be reduced by unplugging or totally switching off, if possible, devices with a standby mode not currently in use; if several devices are used together or only when a room is occupied, they can be connected to a single power strip that is switched off when not needed.

[33] As users of energy and government authorities have become aware of the need not to waste energy, more attention is being paid to the electrical efficiency of devices (fraction of power consumed that achieves functionality, rather than waste heat); this affects all aspects of equipment, including standby power.

Standby power use can be decreased both by attention to circuit design and by improved technology.

Programs directed at consumer electronics have stimulated manufacturers to cut standby power use in many products.

[34] For example, a commercially available computer in Wake-on-LAN standby typically consumed 2 to 8 watts of standby power as of 2011[update], but it was possible to design much more efficient circuitry: a purpose-designed microcontroller can reduce total system power to under 0.5 watts, with the microcontroller itself contributing 42 mW.