Thinkin’ green
by Gloria McConnell, Managing Editor
Should you turn off the computer or leave it running, especially overnight or for other extended periods of idle time? It’s a question that has followed personal computers as long as they have been around. Thanks to today’s technology, you have some choices.
Whatever you do, do not just leave your computer on full throttle. According to the Tufts University Climate Initiative, one computer left on 24 hours a day will cost you $115 – 160 in electricity costs a year and dump 1,500 pounds of CO2 into the atmosphere. A tree absorbs between 3-15 pounds of CO2 each year. That means that 100-500 trees would be needed to offset the yearly emissions of one computer left on all the time!
In this article:
Turning it off
Today’s more convenient options
Screen savers
References
Turning it off
The U.S. Department of Energy (DOE) urges you to turn it off. For energy savings, the DOE guidelines include:
- Monitor: Turn it off if you aren’t going to use your PC for more than 20 minutes.
- Computer: Turn off both monitor and computer if it will be unused for more than 2 hours.
- Power strip: Use a power strip/surge protector for all computer-related components (monitor, printer, other accessories), and turn off the power strip if you are not going to use this equipment for extended periods, because many items continue to draw small amounts of power even if they are turned off.
The DOE points out that, in addition to the energy consumed, PCs also produce heat, so turning them off reduces the loads needed to cool buildings. (A good thing during Arizona summers!)
Does turning off a computer damage it? No! The DOE points out that most PCs reach the end of their “useful” life (due to technological advances) long before any negative impact from switching the computer on and off multiple times might occur. Monte Enbysk, lead editor for the Microsoft.com network, explains that today’s PCs are designed to handle 40,000 on/off cycles before a failure — you likely won’t reach that number during the computer’s five-to-seven-year life span. He points out that in the past, PC hard disks did not automatically park their heads when shut off, and that frequent on/off cycling could damage the hard disks. Today that simply is not the case.
Today’s more convenient options
The DOE does acknowledge that time is money, and if your shutdown/startup routines take a long time, the value of your time may exceed any savings you will gain by saving electricity. There is also the issue of getting yourself back to your previous working state. You may be working in several applications, with several files at once. Getting “back to where you were” may not be insignificant.
Enbysk states that although he shut off his computer at night for many years, he is now convinced you can leave your computer on at night and still conserve as much energy.
If you’re a Windows user (Windows Vista, XP, Windows 2000), using your PC’s “hibernate” feature overnight powers down your monitor to about 5 watts of energy and your PC to 2.3 watts — virtually the same as turning your PC.
Many PCs available today — particularly those with the ENERGY STAR rating — also come with a power-down or sleep mode feature for the CPU and monitor. Sleep mode can reduce your computer’s power consumption to as little as 8 watts, which is less than 10% of its operating power consumption.
In Windows, look for Power Options settings in the Control Panel.
Screen savers
Whatever you do, do not leave on your monitor with the screen saver — it is definitely not an energy saver. Here’s what Don Willmott, Forecast Earth correspondent, has to say on the Yahoo! Green website:
“In the good old days of tube monitors, screen savers such as those unforgettable flying toasters were invented to prevent burn-in, a permanent shadow branded into the phosphors of your monitor by a static image…
Well, flat-screen LCD monitors don’t burn in, so if you still have flying toasters or an endlessly looping slide show of your adorable niece and nephew, you’re behind the times. When you’re not sitting in front of your monitor it should be off off off.”
References
“Climate change is real … turn off your computer!” in the Tufts University Climate Initiative Computer Brochure, www.tufts.edu/tie/tci/pdf/Computer%20brochures.PDF
“Do you need to turn off your PC at night?” by Monte Enbysk on the Microsoft Small Business Center website, http://www.microsoft.com/smallbusiness/resources/technology/hardware/do-you-need-to-turn-off-your-pc-at-night.aspx
“When to Turn Off Personal Computers” in the U.S. Dept. of Energy’s A Consumer’s Guide to Energy Efficiency and Renewable Energy,
http://www.eere.energy.gov/consumer/your_home/appliances/index.cfm/mytopic=10070
“You don’t still use a screen saver, do you?” by Don Willmott on the Yahoo! Green website, http://green.yahoo.com/blog/forecastearth/49/you-don-t-still-use-a-screen-saver-do-you.html
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