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PC power management should not adversely affect the ability of your end users to do their jobs or the ability of the
IT department to maintain the PC fleet. The analysis detailed in this document shows that Windows built-in power
schemes are widely felt to be an annoyance to many end users during the day, since when given the choice, almost
half of end users turn off power scheme based sleep timers completely.
When they are enabled, built-in power scheme sleep timers are only partially effective at saving energy and
therefore cost. Many PCs do not all go to sleep when they should (sleeplessness) and some wake up when they
shouldn t (spurious wakeups), with the result that only 20% of PCs using Windows sleep timers actually go to sleep
and stay that way overnight and at weekends.
It is impossible to monitor and report on the energy used by your PC estate (and therefore the cost and CO
emissions this causes) using only the built-in tools that come with Windows. Because of the lack of built-in
monitoring of energy usage, organizations are unaware of the lack of effectiveness of Windows sleep timers.
Windows power schemes should therefore not be used as the mechanism for reliable overnight and weekend
energy saving for PCs. Scheduled intelligent power downs using NightWatchman are much more successful at
providing power savings, with only 2% of PCs being left on overnight
Data set used in this analysis, compared to Windows built in power schemes, NightWatchman
" Produced cost savings of 39.05 per PC per year
" Reduced emissions by over half a ton of CO2 per PC per year.
This is typical of the savings achieved by many of 1E s NightWatchman customers.
Taking NightWatchman maintenance windows into account