Turning off your computer when it's not in use is a great way to save energy. But did you know that some devices and appliances, including your computer, continue to use power even when they're off?
It's a phenomenon called vampire power, sometimes called standby power or energy leaks. Vampire power is the energy a piece of equipment continues to use even after it's been switched off. In a study done at the Lawrence Berkeley National Laboratory, researchers found that vampire power may consume as much as 15 to 30 watts per appliance [source: California Energy Commission]. Totaled up, it's estimated that more than 5 percent of your power bill can be attributed to appliances in standby mode, which equals about $4 billion consumer dollars spent to feed vampires each year [source: Lawrence Berkeley National Laboratory]. Contributors include any device that relies on standby power, such as televisions, refrigerators, air conditioners, computers, cell-phone chargers and any appliance that maintains (and displays) a clock.
Off is not enough. The stake in the heart of vampire power is to unplug devices.