Your Computer Wastes More Energy Than You Thought

Computer users generally assume that their hardware's sleep and automatic shutdown functions keep their desktops and laptops from wasting energy. But a pair of studies commissioned by the state of California show that idle computers waste a whole lot more energy than we suspect.

The studies, paid for by the California Energy Commission, showed that users often incorrectly believe their computers have energy saving settings enabled when they do not, and that a large majority of computers are left on for more than 23 hours per day, being shut down only during rebooting.

"The considerable amount of energy that is being consumed by computers that are on, but not in use, shows that a large amount of energy could be saved with improved power management," said California Energy Commissioner Andrew McAllister.

The studies focused on computer users in a university setting. More than 2,000 people were interviewed about their computer use habits for the first study, and 125 of their machines were monitored remotely to record their power use status over several weeks for the second study. The data collected in each study was compared, providing an interesting glimpse of mistaken assumptions about energy use and possible ways to make computer use more efficient.

For instance, the first study indicated that users assumed that 84 percent of the computers discussed in the study were set to sleep or shut down after a period of inactivity, while the real-time data recorded in the second study showed that only 20 percent of the machines examined had those automatic settings enabled. Machines in the second study were powered up for an average of 76 percent of the day, but used only for 16 percent of the day.

And according to the first study, users strongly prefer automatic energy saving modes over manually shutting down their machines when not in use. That's partly because in institutional settings, users are asked to leave machines on overnight for maintenance and updates, backups, or remote access. It's also partly because users find restarting a computer from a cold shutdown to be frustratingly slow.

The Energy Commission plans to put the results of the studies to use in drafting new computer and monitor energy efficiency standards. In the meantime, the results serve as a good reminder to Californians to power down their computers manually when they're not going to be in use for a while.

Put it this way: if half of California's 12.5 million households have a desktop computer that's left on for most of the day regardless of whether it's used, that's somewhere between 600 and 1,600 megawatts of power wasted on a nearly constant basis. That's wasting the output of between one and three mid-sized gas-fired power plants.