Standby power
Encyclopedia
Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

("phantom load" and "leaking electricity
Leakage (electronics)
In electronics, leakage may refer to a gradual loss of energy from a charged capacitor. It is primarily caused by electronic devices attached to the capacitors, such as transistors or diodes, which conduct a small amount of current even when they are turned off...

" are actually well-defined technical terms with other meanings, adopted for this different purpose), refers to the electric power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...

 consumed by electronic and electrical appliances while they are switched off (but are designed to draw some power) or in a standby mode
Sleep mode
Sleep mode refers to a low power mode for electronic devices such as computers, televisions, and remote controlled devices. These modes save significant electrical consumption compared to leaving a device fully on and idle, but allow the user to avoid having to reset programming codes or wait for a...

. Some such devices offer remote control
Remote control
A remote control is a component of an electronics device, most commonly a television set, used for operating the television device wirelessly from a short line-of-sight distance.The remote control is usually contracted to remote...

s and digital clock
Digital clock
A digital clock is a type of clock that displays the time digitally, i.e. in cyphers, as opposed to an analog clock, where the time is displayed by hands. Digital clocks are often associated with electronic drives, but the "digital" description refers only to the display, not to the drive mechanism...

 features to the user, while other devices, such as power adapter
Power supply
A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...

s for disconnected electronic devices, consume power without offering any features (sometimes called no-load power).

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, and amounted typically to 10% of the electrical energy usage of the average household. By 2010 regulations were in place in most developed countries restricting standby power of devices sold to one watt (and half that from 2013).

Definition

Most experts agree informally that 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 control
Remote control
A remote control is a component of an electronics device, most commonly a television set, used for operating the television device wirelessly from a short line-of-sight distance.The remote control is usually contracted to remote...

ler. 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, say, an answering machine not dealing with a call renders it useless.

Advantages

Standby power is often consumed for a purpose, although in the past there was little effort to minimise 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.
  • Equipment may use a little power when switched off to power a display, operate a clock, etc.
  • Battery-powered equipment connected to a mains power supply can be kept fully charged although switched on; for example, a mobile telephone can be ready to receive calls without depleting its battery charge.
  • In some cases standby power is consumed for no advantage at all except minor convenience; for example a charger left plugged into power when the mobile telephone it powers and charges is not connected; or a voltage-conversion transformer or uninterruptible power supply connected to equipment which is switched off.

Disadvantages

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
One Watt Initiative
The One Watt Initiative is an energy-saving initiative by the International Energy Agency to reduce standby power-use by any appliance to not more than one watt in 2010, and 0.5 watts in 2013, which has given rise to regulations in many countries and regions.-Standby power:Standby power,...

 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
    Order of magnitude
    An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. In its most common usage, the amount being scaled is 10 and the scale is the exponent being applied to this amount...

     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
    Electricity generation
    Electricity generation is the process of generating electric energy from other forms of energy.The fundamental principles of electricity generation were discovered during the 1820s and early 1830s by the British scientist Michael Faraday...

     by combustion of hydrocarbons (oil, coal, gas) or other substances, which releases substantial amounts of carbon dioxide
    Carbon dioxide
    Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

    , implicated in global warming
    Global warming
    Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...

    , and other pollutants such as sulphur dioxide, which produces acid rain
    Acid rain
    Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions . It can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of carbon dioxide, sulfur dioxide and nitrogen...

    . Standby power is a significant contributor to electricity usage.
  • As electricity consumption increases, more power station
    Power station
    A power station is an industrial facility for the generation of electric energy....

    s are needed, with associated capital and running costs.

Magnitude

Standby power makes up a portion of homes' miscellaneous electric load
Miscellaneous electric load
Miscellaneous electric loads in buildings are electric loads resulting from electronic devices not responsible for space heating, cooling, water heating, or lighting...

, 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 to 15 watts per device, and occasionally more. Regulations coming into force in many countries following the One Watt Initiative
One Watt Initiative
The One Watt Initiative is an energy-saving initiative by the International Energy Agency to reduce standby power-use by any appliance to not more than one watt in 2010, and 0.5 watts in 2013, which has given rise to regulations in many countries and regions.-Standby power:Standby power,...

 restrict standby power of new equipment to not more than one watt from 2010, 0.5 watts from 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 2006 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. Similar findings were made in other developed countries, including the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, with some estimates of the share of standby power consumption over 10%, the highest approaching 13%.

A report produced in 2004 for the California Energy Commission has a very large list of the standby and operational power consumed by a great many devices (typical examples, there is no general rule), down to a baby monitor and toothbrush charger.

Many household appliances are never fully switched off, but spend most of the time in a standby mode. A 1998 study estimated that devices on standby accounted for about 5% of U.S. residential electricity consumption, "adding up to more than $3 billion in annual energy costs". A 2000 study said standby power accounted for around 10% of household power-consumption. A 2004 United States Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...

 report found that national residential electricity consumption was 1.29 billion megawatt hours (MWh). 5% of that equals 64 million MWh, about the output of 18 x 400MW power stations running 24 hours per day/365 days per year.

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 (1W × 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 9kWh for each watt of continuous consumption. More energy can be saved by replacing incandescent lamps by fluorescent
Fluorescent lamp
A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful...

 or LED lamp
LED lamp
An LED lamp is a solid-state lamp that uses light-emitting diodes as the source of light. The LEDs involved may be conventional semiconductor light-emitting diodes, organic LEDs , or polymer light-emitting diodes devices, although PLED technologies are not currently commercially available.Since...

s; standard and compact fluorescent lamp
Compact fluorescent lamp
A compact fluorescent lamp , also called compact fluorescent light, energy-saving light, and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent lamp; some types fit into light fixtures formerly used for incandescent lamps...

s use a third to a fifth as much electricity for the same light, LEDs less.

Continuous low power consumption is needed for some devices, such as security systems, fire alarms, and many digital video recorders on standby, to operate properly. Some such consumption, such as low power used by timers to switch off devices which would otherwise waste energy, can reduce total energy usage. The Reducing Consumption section below provides information on reducing standby power.

Fire risks

There is a risk of fire from devices in standby mode. There are reports of televisions, in particular, catching fire in standby mode.

Before the development of modern semiconductor electronics it was not uncommon for devices, typically television receivers, to catch fire when plugged in but switched off, sometimes when fully switched off rather than on standby. This is much less likely with modern equipment, but not impossible. Older cathode-ray tube display equipment (television and computer displays) had high voltages and currents, and was far more of a fire risk than thin panel LCD and other displays.

Contributing factors for electrical fires include:
  • Damp environments
  • Lightning
    Lightning
    Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

     strikes affecting building wiring
  • Age of the appliance—older appliances are less well designed for safety, and may have deteriorated


A modern HD
High-definition television
High-definition television is video that has resolution substantially higher than that of traditional television systems . HDTV has one or two million pixels per frame, roughly five times that of SD...

 LCD television may use 1 W or less in standby mode, and 80–125 W, depending on size and circuit design, during operation.

Policy

The One Watt Initiative
One Watt Initiative
The One Watt Initiative is an energy-saving initiative by the International Energy Agency to reduce standby power-use by any appliance to not more than one watt in 2010, and 0.5 watts in 2013, which has given rise to regulations in many countries and regions.-Standby power:Standby power,...

 was launched by the IEA
International Energy Agency
The International Energy Agency is a Paris-based autonomous intergovernmental organization established in the framework of the Organisation for Economic Co-operation and Development in 1974 in the wake of the 1973 oil crisis...

 in 1999 to ensure through international cooperation that by 2010 all new appliances sold in the world only use one watt in standby mode. This would reduce CO2 emissions by 50 million tons in the OECD countries alone by 2010.

In July 2001 U.S.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 President George W. Bush
George W. Bush
George Walker Bush is an American politician who served as the 43rd President of the United States, from 2001 to 2009. Before that, he was the 46th Governor of Texas, having served from 1995 to 2000....

 signed an Executive Order directing federal agencies to "purchase products that use no more than one watt in their standby power consuming mode".

In July 2007 California's 2005 appliance standards came into effect, limiting external power supply standby power to 0.5 watts.

On 6 January 2010 the European Commission
European Commission
The European Commission is the executive body of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union....

 (EC) Regulation No 1275/2008 came into force. 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, "standby plus" power (providing information or status display in addition to possible reactivation function) shall not exceed 2W. Equipment must where appropriate provide off mode and/or standby mode when the equipment is connected to the mains power source. These figures are halved on 6 January 2013.

Identifying devices

The following types of devices consume standby power.
  • Transformer
    Transformer
    A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...

    s for voltage conversion.
  • Wall wart
    Wall wart
    The AC adapter, AC/DC adapter or AC/DC converter is a type of external power supply, often enclosed in what looks like an over-sized AC plug. Other names include plug pack, plug-in adapter, adapter block, domestic mains adapter, line power adapter, or power adapter...

     power supplies powering devices which are switched off.
  • Many devices with "instant-on" functions which respond immediately to user action without warm-up delay.
  • Electronic and electrical devices in standby mode which can be woken by a remote control, e.g. some air conditioners, audio-visual equipment such as a television
    Television
    Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...

     receiver
  • Electronic and electrical device which can carry out some functions even when switched off, e.g. with an electrically powered timer. Most modern computer
    Computer
    A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

    s consume standby power, allowing them to be woken remotely (by Wake on LAN, etc.) or at a specified time. These functions are always enabled even if not needed; power can be saved by disconnecting from mains (sometimes by a switch on the back), but only if functionality is not needed.
  • Uninterruptible power supplies (UPS)
  • Cordless telephones and answering machines
  • Timers which operate devices


Other devices consume standby power which is required for normal functioning that cannot be saved by switching off when not in use. For these devices electricity can only be saved by choosing units with minimal permanent power consumption:
  • Security systems and fire alarms
  • Transformer-powered doorbells
  • Programmable thermostats
  • Motion sensors, light sensors, built-in timers and automatic sprinklers

Estimating standby power

Standby power consumption can be estimated using tables of standby power used by typical devices, although standby power used by appliances of the same class vary extremely widely (for a CRT computer display standby power is listed at a minimum of 1.6 W, maximum 74.5 W). Total standby power can be estimated by measuring total house power with all devices standing by, then disconnected, but this method is inaccurate and subject to large errors and uncertainties.

Measuring standby power

The power wasted in standby must go somewhere; it is dissipated as heat. The temperature, or simply perceived warmth, of a device on standby long enough to reach a stable temperature gives some idea of power wasted.

For most home applications, wattmeters give a good indication of energy used, and some indication of standby consumption.

A wattmeter
Wattmeter
The wattmeter is an instrument for measuring the electric power in watts of any given circuit.An instrument which measures electrical energy in watt hours is essentially a wattmeter which accumulates or averages readings; many such instruments measure and can display many parameters and can be...

 is used to measure electrical power. Inexpensive plugin wattmeters, sometimes described as energy monitors, are available from prices of around US$10. Some more expensive models for home use have remote display units. In the USA wattmeters can often also be borrowed from local power authorities or a local public library. Although accuracy of measurement of low AC current and quantities derived from it, such as power, is often poor, these devices are nevertheless indicative of standby power, if sensitive enough to register it. Some home power monitors simply specify an error figure such as 0.2%, without specifying the parameter subject to this error (e.g., voltage, easy to measure), and without qualification. Errors of measurements of very low power may be a much larger percentage of the reading. Professional equipment capable of but not specifically designed for low-power measurements clarifies typically that the error is a percentage of full-scale reading, or a percentage of reading plus a fixed amount, and valid only within certain limits.

In practice accuracy of measurements by meters with poor performance at low power levels can be improved by connecting a fixed load such as an incandescent light bulb, adding the device in standby to measure, and using the difference in power consumption.

Less expensive wattmeters may be subject to significant inaccuracy at low current (power). They are often subject to other errors due to their mode of operation:
  • If the load is highly reactive
    Reactance
    Reactance is the opposition of a circuit element to a change of electric current or voltage, due to that element's capacitance or inductance. A built-up electric field resists the change of voltage on the element, while a magnetic field resists the change of current...

    , the power shown by some meters may be inaccurate. Meters specified to read "rms power" or capable of displaying power factor do not have this problem.
  • Many ac meters are designed to give readings which are only meaningful for the sinusoidal waveforms of normal ac power. Waveforms for switching power supplies as used in much electronic equipment may be very far from sinusoidal, causing power readings of such meters to be meaningless.

Laboratory-grade equipment, which costs from several hundreds of US dollars and is sometimes large, can measure power down to very low values without any of these effects. The US IEC
Independent Electrical Contractors
The Independent Electrical Contractors, Inc. is a national trade association for merit shop electrical and systems contractors. IEC’s mission is to develop and foster a stronger economy through the level of quality and services its members provide to the industry.IEC believes that drawing from the...

 62301 recommendation for measurements of active power is that power of 0.5W or greater shall be made with an uncertainty of 2%. Measurements of less than 0.5W shall be made with an uncertainty of 0.01W. The power measurement instrument shall have a resolution of 0.01W or better.

Operating practices

Power waste can be reduced by setting computers and computerized devices to power-saving mode, rather than leaving them running when not in use. Most computers have power schemes that allow the computer to go into a system standby mode after a predetermined time without activity (by keyboard, mouse, communications, etc.). (Screen savers
Screensaver
A screensaver is a type of computer program initially designed to prevent phosphor burn-in on CRT and plasma computer monitors by blanking the screen or filling it with moving images or patterns when the computer is not in use...

 are designed to prevent screen burn, and do not save power.)

Some equipment has a quick-start mode; standby power is eliminated if this mode is not used. Video game consoles often use power when they are turned off, but the standby power can be further reduced if the correct options are set. For example, a Wii
Wii
The Wii is a home video game console released by Nintendo on November 19, 2006. As a seventh-generation console, the Wii primarily competes with Microsoft's Xbox 360 and Sony's PlayStation 3. Nintendo states that its console targets a broader demographic than that of the two others...

 game can go from 18 watts to 8 watts to 1 watt by turning off the WiiConnect24 and Standby Connection options.

Devices that have rechargeable batteries and are always plugged in use standby power even if the battery is fully charged. Corded appliances such as vacuum cleaners, electric razors, and simple telephones do not need a standby mode and do not consume the standby power that cordless equivalents do.

Older devices with power adapters that are large and are warm to the touch use several watts of power. Newer power adapters that are lightweight and are not warm to the touch may use less than one watt.

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
Power strip
A power strip is a block of electrical sockets that attaches to the end of a flexible cable and allows multiple electrical devices to be plugged in. As such it can be considered a type of trailing socket though that term is more often used for single and double cable mounted sockets...

 which is switched off when not needed. This may cause some electronic devices, particularly older ones, to lose their configuration settings.
Timers can be used to turn off standby power to devices that are unused on a regular schedule. Switches that turn the power off when the connected device goes into standby, or that turn other outlets on or off when a device is turned on or off are also available. Switches can be activated by sensors. Home automation
Home automation
Home automation is the residential extension of "building automation". It is automation of the home, housework or household activity. Home automation may include centralized control of lighting, HVAC , appliances, and other systems, to provide improved convenience, comfort, energy efficiency and...

 sensors, switches and controllers can be used to handle more complex sensing and switching. This produces a net saving of power so long as the control devices themselves use less power than the controlled equipment in standby mode.

Standby power consumption of some computers can be reduced by turning off components that use power in standby mode. For instance, disabling Wake-on-LAN
Wake-on-LAN
Wake-on-LAN is an Ethernet computer networking standard that allows a computer to be turned on or woken up by a network message....

 (WoL), "wake on modem", "wake on keyboard" or "wake on USB" may reduce power when in standby. Unused features may be disabled in the computer's BIOS
BIOS
In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....

 setup to save power.

Devices were introduced in 2010 which allows the remote controller for equipment to be used to totally switch off power to everything plugged into a power strip. It was claimed in the UK that this could save £30, more than the price of the device, in one year.

Equipment efficiency

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
Efficiency
Efficiency in general describes the extent to which time or effort is well used for the intended task or purpose. It is often used with the specific purpose of relaying the capability of a specific application of effort to produce a specific outcome effectively with a minimum amount or quantity of...

 of devices (fraction of power consumed which achieves functionality, rather than waste heat); this affects all aspects of equipment, including standby power. Efficiency is increasing and standby power decreasing, 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. It is probably technically feasible to reduce standby power by 75% overall; most savings will be less than a watt, but other cases will be as large as 10 watts.

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

See also

  • Green computing
    Green computing
    Green computing or green IT, refers to environmentally sustainable computing or IT. In the article Harnessing Green IT: Principles and Practices, San Murugesan defines the field of green computing as "the study and practice of designing, manufacturing, using, and disposing of computers, servers,...

  • Low-power electronics
    Low-power electronics
    Low-power electronics means that the consumption of electric power is deliberately low, e.g. notebook processors.- Computing elements :The density and speed of integrated-circuit computing elements have increased exponentially for several decades, following a trend described by Moore's Law...

  • Miscellaneous electric load
    Miscellaneous electric load
    Miscellaneous electric loads in buildings are electric loads resulting from electronic devices not responsible for space heating, cooling, water heating, or lighting...

  • Wall wart
    Wall wart
    The AC adapter, AC/DC adapter or AC/DC converter is a type of external power supply, often enclosed in what looks like an over-sized AC plug. Other names include plug pack, plug-in adapter, adapter block, domestic mains adapter, line power adapter, or power adapter...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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