PC and monitor night status: Power management enabling and manual turn-off

While office equipment accounts for about 7 percent of commercial building energy use, this reflects considerable energy savings from the use of automatic power management. Most of these savings were gained through the use of low-power modes that meet the criteria of the U.S. EPA's Energy Star program. Despite this success, there are large amounts of additional savings that could be gained if all equipment capable of power management use were enabled and functioning. A considerable portion of equipment is not enabled for power management at all, enabled only partially, or is enabled but prevented from functioning. Additional savings could be gained if more equipment were turned off at night manually. We compiled results from 17 studies from the office equipment literature addressing PCs and monitors. Some factors important for annual energy use, such as power levels, have been documented elsewhere and are not covered. We review methods for estimating office equipment use patterns and energy use, and present findings on night status--power management and manual turn-off rates. In early studies, PC power management was often found to function in 25 percent or less of the Energy Star compliant units (10 percent of all PCs). However, recent assessments have found higher rates, and we estimate that for Energy Star models, 35 percent of PC CPUs and 65 percent of PC monitors are enabled for power management. While the data lack statistical rigor, they can be used to estimate the magnitude of current and potential power management savings, which we did for major types of office equipment. The data also make clear that the topic of enabling rates, and the factors which influence them, deserve greater scrutiny