According to two studies commissioned by the California Energy Commission, computers are not going into sleep mode or automatically being turned off as often as users think, leaving opportunities to save more energy. The implications of the research are that workplace desktop computers consume significant amounts of energy even when not in use.
The first study, "A Survey of Computer Power Modes Usage in a University Population," surveyed more than 2,000 respondents to obtain detailed information about the use of more than 3,000 office desktops, home desktops, and laptops. This large user-centric study is unique compared to most previous studies because of the focus on user behaviors regarding power management features.
"People think when they leave their workstation, the computer will reduce its own energy consumption after a specified amount of time," said Commissioner Andrew McAllister, the agency's lead on energy efficiency issues. "These studies show a strong desire and intent by computer users to reduce energy use. Identified user error and knowledge gaps indicate significant room for improvement in the power management options and interfaces available to computer users."
Computers have built-in power management software — with settings such as sleep, hibernate and shutdown — that enables computers and monitors to consume less energy when not in use; however, these features are not delivering the full energy savings potential.
- Respondents report using automatic power management features over manual modes. The survey showed that 39% of the time users regularly use manual controls to put office desktop computers into sleep, hibernate, or off modes. Of those office desktops not taking advantage of automatic power management, 61% are left on all the time.
- Users changed power management settings themselves in 50% of laptops, 41% of home desktops and 20% in office desktops. Respondents have less control over their office desktops than their laptops or home desktops.
- According to the survey, the two main reasons computers were left on, even when not in use for hours, are that users felt restarting is too slow and the belief the computer will automatically go into sleep or other lower-power mode. For office desktops, two other main reasons were "need to leave computer on for updates or backups" and "needs to be available for remote access."
The second study, "Monitoring Computer Power Modes Usage in a University Population," used software to remotely monitor 125 computers in the first study, 24 hours a day for several weeks. Research was gathered by monitoring actual computer usage patterns, a supplementary questionnaire, and direct observations of computers' power management settings. The findings were compared to those of the first study.
Among the findings of the second study:
- The monitoring study showed a large difference between direct observation of user's computer settings and their survey responses. Researchers observed that 20% of computers had automatic power management enabled whereas the survey responses indicated that 84% of computers had at least one automatic power setting enabled. The data suggest users incorrectly believe automatic settings are engaged when they are not.
- Workplace desktop computers are on 76% of the day, even though they were only being used 16% of the day. Sleep mode was enabled for about 7% of the day.
- Overall, workplace desktop computers in the study were on and not being used more than 60% of the time. If computers had manually or automatically been turned off or put in sleep mode, energy use would be less.
- The majority of computers (69%) are off for less than 5% of the time, and most of those are off for a few minutes a day, likely when rebooting.
"The considerable amount of energy that is being consumed by computers that are on, but not in use, shows that with better power management alternatives, a large amount of energy could be saved with improved power management features," McAllister said.
The California Plug Load Research Center conducted the two studies to better understand computer use patterns and identify potential ways to reduce energy waste in California. The Energy Commission will use these studies to supplement other research as it develops a draft staff proposal for computer and monitor energy efficiency standards.