Black boxes can be energy vampires

January 27, 2008

It seems like all the electronic equipment I have has a black box that I have to plug into the wall. What’s it for and does it add up to a lot of electricity being used, considering how many toys we all have? 

You’re right. It seems every gadget we buy comes with the ubiquitous clunky, black brick that plugs into an outlet. As many as 1.5 billion of these external power adaptors are in use in the country, according to Energy Star®, the federal program that promotes efficient energy use. That equals about five power adaptors for every person in the United States. Couple that with battery chargers needed for devices such as cell phones, power tools and digital cameras and our homes are swimming in black boxes being plugged in at any one time.

Beware of secret energy vampires
These black boxes are external power supplies, sometimes called power adaptors. They act as mini-transformers converting 120-volt alternating current coming from the outlet into a lower voltage needed to operate the electronic device. However, most of them lose anywhere between 40 to 70 percent of the electricity in the conversion process. This lost electricity is called a conversion loss. Some loss may be because of the converter itself, but some is caused by the actual electronic device drawing the electricity. Either way that “lost” electricity costs you money.

Other types of electronics have been called energy vampires by some in the electric industry because the devices continue to draw electricity even when the device is switched off. Devices such as TV sets, a personal computer, VCR, MP3 player or DVD player draw power as long as they are plugged in. This power consumption is called standby power. (This is different from the standby or sleep modes on your computer.)

According to the Lawrence Berkeley Lab, in Berkeley, Calif., standby power use can be as high as 15 or 20 watts. Alan Meier with the Laboratory says a typical household could have more than 40 devices using energy when turned off.

“I don’t know how much standby energy is being wasted, but I can tell you how much is probably being used – 5 to 8 percent of residential use,” he said.

Cut your losses
Unplugging the gadgets is the only way to totally eliminate these losses. But that’s not always practical – think about resetting clocks and timers each time you re-plug them in. However, in most of our homes there are electronics we seldom use that could be unplugged, such as a TV in the spare bedroom, a VCR still waiting for a cassette or rechargeable tools seldom used.

Meier said another solution is to plug a cluster of connected products into a switched power strip and turn them off all at once. Again, you’ll have to be careful of items with clocks or network connections.

More efficiency available
External power supplies and battery chargers are available with the Energy Star label. These external power supplies are 30 percent more energy efficient and typically lighter and smaller. Similarly, Energy Star qualified battery chargers use about 35 percent less energy.

In addition, the 2007 Energy Independence and Security Act signed into law in December 2007, includes provisions to set efficiency standards for both standby power and external power supplies. Starting in July 2008, external power supplies will need to meet these national standards.

Unfortunately, battery chargers were not addressed in the new legislation, despite the fact that they can draw as much as five to 20 times more energy than stored. Energy Star estimates that more efficient chargers could save consumers more than $100 million annually in energy costs and prevent the release of more than one million tons of greenhouse gas emissions. Given those numbers, it pays to unplug chargers when they’ve done their job or replace them with Energy Star qualified ones.