Tuesday, October 18, 2011

Fact or Fable

Fact or Fable? Consumer Electronics Use More Energy When They Are Turned Off

Key Points
  • Many consumer electronics devices continue to draw standby power when they are not being used.
  • While electronics draw more power when turned on, standby power makes up the majority of total energy use in some devices.
  • Unplugging electronic devices is the most effective way to reduce standby power losses.
Source: http://www.sxc.hu/
DVD Player
This is both a fact and a fable. The typical American household contains 24 electronic products, according to the Consumer Electronics Association. Many of these devices continue to draw power when they are turned off, or are not actively being used. This is commonly known as standby power. While electronics draw more power when they are turned on, certain devices—such as cable boxes and laptop computers—are typically in standby power mode for such long periods of time each day that it makes up the majority of their total energy use.
A study by the Consumer Electronics Association found that for electronics as a whole, 68% of total energy use takes place during active use. Off mode accounts for 24% of energy use, while idle or sleep mode makes up the remaining 8%. Off mode means the device is turned off, but still plugged in, while equipment in idle mode is turned on, but not being used. (Roth 2007)
Energy use varies by device, however. The following table compares the active and standby power use of commonly-used consumer electronics equipment:
Annual Energy Use of Electronics Devices By Power Mode
DeviceActiveIdleOff
Compact Audio23%15%62%
DVD Player12%27%61%
TV Set Top (Cable or Satellite) Box32%N/A68%
Laptop Computer82%3%15%
As the table indicates, the off mode accounts for more than 60% of the energy use of set-top boxes and audio video equipment, while active mode dominates energy consumption for laptop computers. Why the difference? Electronic devices vary in how they are used and in their power draw (how much energy they use at any given time). For example, set-top boxes and laptop computers are generally in active use about one-third of the time. However, laptops have a substantially higher power draw in active mode, while set-top box power draw is about the same whether turned on or off. That is why two-thirds of set-top energy use takes place in off mode.

Reducing Standby Energy Losses

The average U.S. household spends $100 per year to power electronics and appliances while they are standby power mode, according to the U.S. Department of Energy. So what can you do to stop wasting your energy dollars?
  • Unplug devices that are rarely used. An example would be a television and DVD player in the guest room.
  • Unplug battery chargers for electronic devices when the batteries are fully charged or the chargers are not in use.
  • Use a power strip as a central shut-off point for clusters of electronics products, such as a home office or entertainment console.
  • Purchase ENERGY STAR qualified electronics that have low standby power and other power management features. When installing a Pay TV service, ask the supplier to provide an ENERGY STAR qualified set-top box.

References

Roth, Kurt W., et al. Energy Consumption by Consumer Electronics in U.S. Residences. Cambridge, MA. 2007.

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