For systems that provide auxiliary power, see Emergency power system.
“Phantom load” redirects here. For microphone powering technique, see Phantom power.
“Idling current” redirects here. For transistor quiescent current, see Biasing.
Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity (“phantom load” and “leaking electricity” are defined technical terms with other meanings, adopted for this different purpose), refers to the electric power consumed by electronic and electrical appliances while they are switched off (but are designed to draw some power) or in a standby mode. This only occurs because some devices claimed to be “switched off” on the electronic interface, but are in a different state from switching off at the plug, or disconnecting from the power point, which can solve the problem of standby power completely. In fact, switching off at the power point is effective enough, there is no need to disconnect all devices from the power point. Some such devices offer remote controls and digital clock features to the user, while other devices, such as power adapters for disconnected electronic devices, consume power without offering any features (sometimes called no-load power). All of the above examples, such as the remote control, digital clock functions and—in the case of adapters, no-load power—are switched off just by switching off at the power point. However, for some devices with built-in internal battery, such as a phone, the standby functions can be stopped by removing the battery instead.
In the past, standby power was largely a non-issue for users, electricity providers, manufacturers, and government regulators. In the first decade of the twenty-first century, awareness of the issue grew and it became an important consideration for all parties. Up to the middle of the decade, standby power was often several watts or even tens of watts per appliance. By 2010, regulations were in place in most developed countries restricting standby power of devices sold to one watt (and half that from 2013).
Standby power is electrical power used by appliances and equipment while switched off or not performing their primary function, often waiting to be activated by a remote controller. That power is consumed by internal or external power supplies, remote control receivers, text or light displays, circuits energized when the device is plugged in even when switched off, etc. Power can be saved by disconnecting such devices, causing at worst only inconvenience.
While this definition is inadequate for technical purposes, there is as yet no formal definition; an international standards committee is developing a definition and test procedure.
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, switching off to save power is not an option. Timers, powered thermostats, and the like are other examples. An uninterruptible power supply could be considered to be wasting standby power only when the computer it protects is off. Disconnecting standby power proper is at worst inconvenient; powering down completely, for example an answering machine not dealing with a call, renders it useless.
Advantages and disadvantagesEdit
Standby power is often consumed for a purpose, although in the past there was little effort to minimize power used.
It may enable a device to switch on very quickly without delays that might otherwise occur (“instant-on”). This was used, for example, with CRT television receivers (now largely supplanted by thin solid-state screens), where a small current was passed through the tube heater, avoiding a delay of many seconds in starting up.
It may be used to power a remote control receiver, so that when infrared or radio-frequency signals are sent by a remote control device, the equipment is able to respond, typically by changing from standby to fully on mode.
Standby power may be used to power a display, operate a clock, etc., without switching on the equipment to full power.
Battery-powered equipment connected to mains electricity can be kept fully charged although switched on; for example, a mobile telephone can be ready to receive calls without depleting its battery charge.
The disadvantages of standby power all relate to the energy used. As standby power is reduced, the disadvantages become less. Older devices often used ten watts or more; with the adoption of the One Watt Initiative by many countries, standby energy use is much diminished.
Devices on standby consume electricity which must be paid for. The total energy consumed may be of the order of 10% of the electrical energy used by a typical household, as discussed below. The cost of standby energy is easily estimated—each watt of continuous standby consumes about 9kWh of electricity per year, and the price per kWh is shown on electricity bills.
Electricity is very often generated by combustion of hydrocarbons (oil, coal, gas) or other substances, which releases substantial amounts of carbon dioxide, implicated in global warming, and other pollutants such as sulphur dioxide, which produces acid rain. Standby power is a significant contributor to electricity usage.
As electricity consumption increases, more power stations are needed, with associated capital and running costs.
Standby power makes up a portion of homes’ miscellaneous electric load, which also includes small appliances, security systems, and other small power draws. The U.S. Department of Energy said in 2008:
“Many appliances continue to draw a small amount of power when they are switched off. These “phantom” loads occur in most appliances that use electricity, such as VCRs, televisions, stereos, computers, and kitchen appliances. This can be avoided by unplugging the appliance or using a power strip and using the switch on the power strip to cut all power to the appliance.”
Standby power used by older devices can be as high as 10–15 W per device, while a modern HD LCD television may use less than 1 W in standby mode. Some appliances use no energy when turned off. Many countries adopting the One Watt Initiative now require new devices to use no more than 1 W starting in 2010, and 0.5 W in 2013.
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 being continuously plugged in resulted in energy usage before the One Watt regulations of 8 to 22 percent of all appliance consumption in different countries, 32 to 87W, and around 10 percent of total residential consumption. In Britain in 2004 standby modes on electronic devices accounted for 8% of all British domestic power consumption. A similar study in France in 2000 found that standby power accounted for 7% of total residential consumption.
In 2004, the California Energy Commission produced a report containing typical standby and operational power consumption for 280 different household devices, including baby monitors and toothbrush chargers.
Over a decade ago some electronics, such as Microwaves, CRT’s and VHS players used more standby power than appliances manufactured in the last 5 years. For a historical reference please see this article from the Economist.
In the US the average home used an average of 11,040 kWh of electricity per year in 2010. Each watt of power consumed by a device running continuously consumes about 9kWh (1 W × 365.25 days/year × 24 hours/day) per year, a little less than one thousandth of the annual US household consumption. Unplugging a device constantly consuming standby power saves a yearly 9 kWh for each watt of continuous consumption.
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). The Reducing Consumption section below provides information on reducing standby power.
Determining standby power
Reducing standby consumptionEdit