Ever notice that little green or red light on your DVD player or stereo that stays on even after you've turned the device off? Think of that light as a reminder: Even though you're not using it, this thing is costing you money.
Many of the devices and appliances we use in our homes and offices actually stay on after they're shut down, using something called standby power.
"Standby power is the power some electronic devices use when they're idle," explained Steven Nadel, executive director of the American Council for an Energy-Efficient Economy, or ACEEE. "A TV set, for example, is normally off but is using a small amount of power to recognize the remote control so you can turn it on."
Everything from microwave ovens and copy machines, to video game consoles and TV sets use standby power when they're idle. For the average consumer the cost can add up, but it also takes a toll on the environment and until something is done about it, the cost of turning things off will continue to rise.
Consider that in the United States there are roughly 110 million households and that each of those homes has about half-a-dozen devices that use standby power.
"In a typical American home we think that standby use is somewhere around 4 to 8 percent," said Alan Meier, a staff scientist at Lawrence Berkley National Laboratories specializing in energy use and efficiency. "About one month's worth of electricity use every year is being used by devices that are switched off or not fulfilling their primary purpose."
While it's hard to pin down a dollar amount, due to the lack of substantial research on the subject, Nadel says it costs consumers tens of dollars a year and costs the economy billions.
But the financial cost of using these products is just one of the high prices we pay. Standby power also takes its toll on the environment from the increased output of power plants and the building of new ones to meet demand.
"We estimate that standby power consumption is responsible for 1 percent of the world's CO2 emissions," he said.
Meier says that in some cases it's necessary for devices to use a small amount of power while not being used and that eliminating standby completely is unlikely to happen. But he also says that most consumers likely aren't aware of just how much power is being consumed.
Some of the audio devices his team has researched used 25 watts of power when they were on and 24 watts when they were off.
"You need to have some power consumption to provide a minimum level of functionality or service -- you have to run a clock or the remote control sensor needs to be on, " Meier said. "But keep in mind that you have a watch on your wrist or maybe a mobile phone in your pocket and it uses a 1/1000th of the power as some of these devices."
So why do manufacturers make products that suck so much power out of the system when they're off, despite the negative effects?
It comes down to dollars and cents. When a cable provider, for example, buys tens-of-thousands of set-top boxes for its customers -- known to be some of largest consumers of standby power -- they can choose between the more expensive ones that use just a small amount of standby, or the less expensive ones that use lots of standby power.