Note: This story was updated on May 7 to add information from a study released by the National Resources Defense Council on that date.
You shut down your computer. You turn off your TV. You take the popcorn out of the microwave. And yet all of these devices and more continue to suck electricity.
This vampire power, also called phantom power, idle load, or standby power,keeps going even after the device is turned off. How much does it waste? Hundreds of dollars per year, according to some estimates. In fact, the Natural Resources Defense Council (NRDC) published a study after this story was first published indicating that vampire power cost $19 billion per year-about $165 per U.S. household. The report estimates that "idle load electricity represents on average nearly 23 percent of household electricity consumption in northern California homes."
But the numbers are difficult to pin down. Alan Meier, a senior scientist at the Lawrence Berkeley National Laboratory estimated "that we're somewhere on the order of five percent." He described that as a "hunch."
Power vampires fear smart surge suppressors such as Belkin's Conserve Smart AV2, because those devices can shut off power to connected devices.
I can't test everyone. So I set out to find out which devices in my own home waste electricity when they're not used, and how much they waste. These are my results.
What exactly is vampire power?
When you turn a modern device "off," it probably stays on in a low-power mode. Common culprits include computers, HDTVs, A/V receivers, printers, and your microwave. Any one such device isn't going to use up a lot of power. But if you have 10 or 20, the waste builds.
It's called vampire power because when it's supposed to be dead, it still sucks.
Three signs can tell you without a doubt that a turned-off device is using juice:
1. Something on it is glowing-usually an LED. The Simpsons parodied this issue brilliantly.
2. You can turn it on or give it a command from a remote control, a smartphone, or over a network.
3. It knows the time as soon as it comes on.
But I won't give the designation vampire to everything that matches one of these attributes. While a device needs power to do any of these, it doesn't have to use much. Some really use so little power that it's inconsequential.
How we use and pay for electricity
According to a U.S. Energy Information Administration report, in 2013, the average American home used 909 kilowatt hours (KWh) a month.
Quick definition: A watt hour (Wh) is a measurement for wattage used over time. For instance, if you leave a 40-watt lightbulb on for one hour, you will use 40Wh. A kilowatt hour (KWh) is, of course, 1000Wh.
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