A screen saver is not an energy saver. According to the U.S. Department of Energy, 75% of all the electricity consumed in the home is standby power used to keep electronics running when those TVs, DVRs, computers, monitors and stereos are "off." The average desktop computer, not including the monitor, consumes from 60 to 250 watts a day. Compared with a machine left on 24/7, a computer that is in use four hours a day and turned off the rest of the time would save you about $70 a year. The carbon impact would be even greater. Shutting it off would reduce the machine's CO2 emissions 83%, to just 63 kg a year.