Standby power

For systems that provide auxiliary power, see Emergency power system.

"Phantom load" redirects here. For microphone powering technique, see Phantom power.

Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity, refers to the electric power consumed by electronic appliances while they are switched off or in a standby mode. Some such devices offer remote controls and digital clock features to the user, while other devices, such as power adapter for laptop computers and other electronic devices, consume power without offering any features. This latter case is sometimes distinguished as no load power.

Consequences

Standby power makes up a portion of homes' miscellaneous electric load, which also includes small appliances, security systems, and other small power draws.

Standby power can be as high as 10 to 15 watts per device, and occasionally more. Due in part to California regulations, a modern appliance (2007 and newer) must use less than 0.5 watts on standby. For example, a typical LCD television display uses less than 0.3 watts on standby. A 2005 study estimates the number of standby appliances in the EU at 3.7 billion. Although the power needed for functions like displays, indicators, and remote control functions is relatively small, the fact that the devices are continuously plugged in, and the number of such devices in the average household means that the energy usage can reach 22 percent of all appliance consumption, and around 10 percent of total residential consumption.

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

The average American home uses 11,040 kWh of electricity per year. Unplugging a modern TV when not in use could save as much as 9 kWh per year. That would be a savings of only 0.08%. More energy savings would be obtained by converting an incandescent to a fluorescent or a fluorescent to an LED lamp. Keep in mind that some standby power requirements are needed for devices such as security systems or fire alarms. Some standby power, such as power needed for timers or programmable thermostats, reduces total electrical usage. The Reducing Consumption section below provides practical advice on reducing standby power.

The British Government's 2006 Energy Review found that standby modes on electronic devices account 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, Australia and Japan, with some estimates of the share of standby power consumption over 10%, highest approaching 13%.

From the U.S. Department of Energy:

"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."

Heat generated

Standby power can heat a room, potentially requiring more power to cool it in hot weather, but less additional power to warm it in cold weather.

Fire risks

The risk of fire from devices in standby mode is debated. There are reported cases where televisions have caught on fire in stand-by mode.

The contributing factors for such fires include:

• Humid environments
• Lightning storms
• Age of the appliance

A modern HD LCD television may use 1W or less when in standby mode, compared to 80-125W during operation.

Policy

Further information: One Watt Initiative

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".

In July 2006, the British Government announced it would outlaw televisions and video players that draw more than 1 watt in standby.

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

In July 2008, the European Commission accepted a proposal to reduce standby power consumption to either 1 W (if there is a reactivation function) or 2 W (if there is an information or status display) by 2010, which will be halved to 0.5 and 1 watt, respectively, by 2012.

Estimating total

An estimate of how much standby power is used can be made using tables of standby power used by typical devices. Measurement of the overall standby power can be made by observing rate of electricity use when all devices are turned off, or when standard loads are in use.

Identifying devices

An appliance watt meter can be used to find out how much energy is used by standby power. Watt meters can often be borrowed from the local power authorities or a local public library. Standby power consumption can oftentimes be indicated qualitatively, if after a several hours of non-operation a device is still warm to touch (usually surface near to the power plug). Such elevated surface temperature will depend on the standby power consumption and the device surface, so small enough standby consumptions cannot be detected in this way.

Devices and functions that can consume standby power

• Power supplies, transformers and inefficient electronic devices
• VCRs, DVD players and most audio systems
• TVs, home cinema suites and set-top boxes
• Microwave ovens
• Cordless phones and answering machines
• Security systems and fire alarms
• Computers, digital monitors and printers
• Door bells
• Timers, motion sensors, light sensors and automatic sprinklers
• Programmable thermostats
• Uninterruptible Power Supply (UPS)
• Devices with "Instant on" functions, with remote control receivers, or waiting for the user to interact
• Devices with a stand-by light or clock
• Power adapters (sometimes referred to as wall warts), whether they are powering a device or not
• Most home video game consoles

• 
  Standby Indicator
• 
  DC Power adaptor

Reducing consumption

The most practical and effective way to reduce standby power in the home is to set computerized devices to power saving mode. Home computers all have Power Schemes that allow the computer to go into a System Standby mode after a predetermined time. Keep in mind that screen savers are not power savers and do not reduce power consumption. Blu-ray players often have a quick-start mode, which should be turned off to reduce standby power to from 5.0 watts to 0.5 watts. Video games 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 game can go from 18 watts to 8 watts to 1 watt by turning off the WiiConnect24 and Standby Connection options.

Products that have batteries and are always plugged-in use standby power. Consider purchasing a corded vacuum cleaner rather than a cordless one to reduce standby consumption. Uninterruptible Power Supply (UPS) units also use significant standby power. Consider saving work more often and not owning an UPS unit. If a flashlight is only used occasionally, consider buying an LED flashlight with regular batteries rather than a flashlight that requires being plugged into a wall. Remember that rechargeable batteries found in devices that are constantly charging have a limited life and may not work properly when they are needed most.

Older devices with power adapters that are large and are warm to the touch should be switched off or unplugged, if possible, because these devices may use several watts of power. However, newer power adapters that are lightweight and are not warm to the touch may use much less than one watt. It may be easier and more effective to look for other ways to reduce energy consumption rather than unplugging recently manufactured products, such as a television, from its outlet.

The simplest way to reduce standby power consumption is to unplug unused devices. Another method is to plug them into a switchable power bar or surge protector with multiple sockets and a real off switch, then switching the power bar on and off as needed. Another alternative is to consider buying energy saving devices or devices that offer a real off switch. Identifying a real off switch can be difficult though, as even devices with a hardware off switch like TVs often still have standby consumption if not taken fully off energy supply. Replacing battery-powered devices, such as cordless phones or rechargeable razors, with corded alternatives not only cuts down on the standby power required to charge the battery, but also reduces energy lost in battery charging and discharging inefficiencies. Many devices use standby power to retain configuration settings and unplugging them will cause these settings to be lost either immediately or shortly after.

A switchable multiple socket or power bar

Switching devices on or off can be automated. Timers can be used to turn off standby power to devices that are unused on a regular schedule. Switches can turn the power off when the connected device goes into standby, or that turn on/off other outlets when a device is turned on or off are also available. Switches can turn on/off based on activity sensors. Home automation sensors, switches and controllers can be used to handle more complex sensing and switching. However, many of these devices in their turn require standby power, as well as requiring energy and resources to make and recycle the device, so care should be taken to assure reduction in power use.

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 modem", "wake on keyboard" or "wake on USB" may reduce power when in standby. Unused features may be disabled in the computer's BIOS setup to save power.

Terms and Usage History

Phantom Load

The earliest known use of the term Phantom load was in "It's Gotta Be Spring" by Brian Green (N6HWY) on page 25 of Home Power Magazine #11, the June/July 1989 issue.

See also

• Green computing
• Low-power electronics
• Miscellaneous electric load
• Wall wart

External links

• Standby Power Home Page, Lawrence Berkeley National Laboratory
• Official Energy Star Website, Energy Star
• International Conference on Standby Power, New Delhi INDIA
• “Phantom Loads”
• “Is a Phantom Stealing Your Electricity?”
• EU States Endorse Steps to Cut Standby Power Use