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A Lawrence Berkeley Lab study from 1999 estimated that one workstation (computer and monitor) left on after business hours is responsible for power plants emitting nearly one ton of CO2 per year. That could be cut by 80 percent if the workstation is switched off at night and set to go to “sleep” during idle periods in the day. If every US computer and monitor were turned off at night, the nation could shut down eight large power stations and avoid emitting 7 million tons of CO2 every year.

Most offices have one computer per desk. Individual computers are not large energy users. But, as they get more powerful—and monitors get larger—they draw more power than they used to. Most new computers come with the ENERGY STAR® label. That’s important to look for, but that label alone doesn’t ensure energy savings. The user needs to be involved too. Even efficient computers that are on all the time still use more energy than they should. The first thing to know is that it’s OK to turn computers off. There’s a myth out there that says you shouldn’t. That’s not true. There’s another myth that screen savers save energy. That’s not true either. When you’re not going to use a computer for more than two hours—and certainly when you’re leaving overnight—the best thing you can do to save energy is just to turn it off. There are times during the workday when computers can be turned off too. ENERGY STAR® computers have a “sleep” mode for when they’re not in use. That feature is often overridden because people worry they may lose important data. To alleviate that, just enable the sleep feature for the monitor and not the computer’s CPU. The monitor uses most of the energy and if it’s shut down when nobody’s at the computer, the savings add up. New flat panel liquid crystal display (LCD) monitors use quite a bit less energy than the conventional cathode ray monitors. The LCD monitors are expensive, but if you are considering new monitors, the energy savings may justify the extra expense.

CASE IN POINT – IBM (worldwide)
The computer giant estimates it saved $17.8 million worldwide in 1991 alone by encouraging employees to turn off equipment and lights when not needed. The company estimates that the effect of these simple changes is the same as if 50,000 cars were removed from the road avoiding some 190,000 metric tons of carbon dioxide emissions.