Computers are not the biggest energy hogs in your house, but, depending on how much you use them, they can become a significant cost. If you use your computer for smaller jobs like word processing and emailing, and if you’re using a laptop or smaller desktop, chances are your computer is using moderate amounts of energy. Your computer’s energy use will increase with its size and with the complexity of the tasks it performs - playing high-tech games will strain your computer and it will suck up power.

The good news is that it’s easy to control your computer’s use. The single most important, and easiest, thing you can do is to set your computer to go to sleep automatically after a short period of non-use. This means the computer will remain on and ready to work whenever you need it, but it can shut down all its non-essential systems and the screen can go blank. If your sleep mode employs a screensaver (if it displays images on the screen) you’re wasting all of the 85 percent of energy use that you would otherwise be saved in sleep mode.

Even better than putting your computer to sleep is turning it off. As long as the computer is plugged in it will use some small amount of power (perhaps 1-5 watts), but besides unplugging it altogether shutdown is the least energy-intensive state for your computer. Some people counter that shutting off your computer daily will run down its hardware, but this is a myth.

In short, it is less energy-intensive to idle your computer than to have it constantly opening programs, burning CDs or playing games; it is (MUCH!) less energy-intensive to put your computer to sleep (without a screensaver) than to idle it; it is less energy-intensive to shut your computer off than to put it to sleep; and it is less energy-intensive to unplug your computer than to leave it on.

For more information on computers and energy use, including a comparison of one very energy-efficient and one very energy-intensive computer, go here.

To see more common myths about computers and energy use debunked, view this brochure of the Harvard Green Campus Initiative.

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