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Power to the powerstrips

February 3, 2010

blue computer by Noerah AlviI got the OK to institute a policy about turning computers off at the end of the day and on weekends and just had to coordinate it with our IT department. Ah! I thought, a quick and easy resolution. But no….(of course not). So, in thinking about what to write I decided to resurrect this topic and also answer some questions: What are the real numbers in terms of savings for shutting down work stations versus sleeping and the energy required to turn computers on? Is the rumor true that it takes a lot of energy to restart a computer – so much that it doesn’t make sense to turn them off?

I proposed to our IT department that staff power down – set equipment to go to “sleep” mode when not in use and turn off their computers and other office equipment when they leave the office (An easy way to turn off all equipment at once is to plug it all into one surge protector with an on/off switch).  They responded by giving me the details of the current office setup, and they did agree that these policies were worth looking into implementing.

To address the rumors first, many articles I found refute the idea that it takes more energy to restart your computer rather than leaving it on. Apparently, the small surge at start-up is still much smaller than what is used when you keep your computer on for lengthy periods of time, and any energy used to shut down and start is more than offset by the period of time that the PC spends totally switched off. Score one point for turning off the PC at night and over weekends. Next.

Our office gets points for using Energy-Star-compliant equipment. A computer meeting the EnergyStar specification will use 20 – 50 percent less energy, depending on how it is used.  And an EnergyStar computer in sleep mode uses 80 percent less energy than when on in full power.

Off vs. sleep vs. hibernate vs. screen saver? This turned out to be fairly easy, too. Screen savers apparently can use 42 watts at a minimum; those with 3-D graphics can use as much as 114.5 watts. When plugged in, the computer uses 3.1 watts in sleep mode and 2.3 watts in hibernate mode. Even when “off” a PC utilizes about 2.3 watts, the same as in hibernate mode. But if we don’t want to use any energy at all, we should be unplugging (or turning off that power strip).

I like the rule of thumb from Monte Enbysk writing for Microsoft for those who may be away from their computers a lot, set the PC to hibernate after 45-60 minutes, which will save your computer memory onto the hard drive, and set it to stand-by after 15 minutes. Stand-by will conserve power (yay) and is meant for shorter absences. It should be easy to get this policy instituted: ENERGYSTAR estimates that setting sleep and hibernate modes will save $25-$75 per year per workstation. For our office, that’s about $9,000.

And Powering down Monitors adds Savings – actually I discovered that monitors should be turned off whenever possible, even if the computer isn’t. One source stated that unlike computers, they use no energy when turned off; whereas they use between 0-15 watts when in sleep or hibernate mode (compared to 100-150 watts used by a regular monitor or 35-45 watts of an LCD monitor when left on). A recommendation for monitors is to set it to sleep after 20 minutes of being idle. An added benefit of enabling a monitor’s power management feature and turning it off when not in use is that it helps it to run cooler and therefore helps it to last longer before needing to be replaced – an added bonus for offices where equipment replacement can add up.

I didn’t find that stat about equipment in stand-by mode still adding up to 10% of an office’s electricity bill, but in 1991 IBM estimated that it saved $17.8 million worldwide by encouraging employees to turn off equipment and lights when not needed. ENERGYSTAR lists this compelling statistic: ‘The EPA has estimated that providing computers with “sleep mode” reduces their energy use by 60 to 70 percent – and ultimately could save enough electricity each year to power Vermont, New Hampshire, and Maine, cut electric bills by $2 billion, and reduce carbon dioxide emissions by the equivalent of 5 million cars’.

Next step will be to write that policy to implement in our office.

— By Briana

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