Cut the Cord and Switch Your Thinking
The Switch Your Thinking campaign encourages Knoxville-area UT employees and students to save energy by turning off computers, printers and other electrical devices at the end of the day or whenever they’re not needed.
But sometimes, just turning a device off isn’t enough. Paul Wilkinson of UT’s Office of Information Technology Lab Services helps answer some commonly-asked questions about saving energy, especially "cutting the cord" and turning off power strips.
Why isn’t it good enough to just turn off electrical appliances if you’re not using them?
"Electrical devices use a small amount of power even when they’re off," Wilkinson says. "They use considerably less power in an off state than on, but the costs can add up if you have several devices in your house or office draining power.
"Some devices can be very inefficient when off. For example, I have a computer speaker system at home that draws 15 watts no matter if it is on or off. It’s a good idea to put devices on a power strip and turn off the power strip when you don’t need to use them," Wilkinson says.
For computer users who don’t want to turn off their machines every time they leave the room, changing the computer’s power settings can also be a good way to save energy, Wilkinson says.
"The modern computer uses anywhere from 40 to 100 watts when on; around 3 watts when in sleep mode; around 2 watts when in hibernate mode; and about 2 watts when turned off but still plugged directly to the wall outlet."
Power settings on Windows PCs can be changed by going to the Start button, then selecting the Control Panel and either Performance and Maintenance or Power Options (depending on your version of Windows). On Macintosh computers, power settings can be changed by selecting System Preferences from the desktop and double-clicking on Energy Saver.
Wilkinson says flat-screen monitors use around 22 watts when on, 3 watts when in sleep mode and zero watts when turned off, unlike PCs. "Screen savers do not save energy," he says; only the power management functions do that.
Can you "wear out" a computer by turning it on and off every time you step away from it?
"This isn’t a problem for modern computers used for a standard life cycle," Wilkinson says. "However, you shouldn’t be turning off your computer every time you step out to go to the restroom. There needs to be a balance of convenience and power saving. The UT Energy Conservation Policy recommends setting computers to hibernate or sleep after 30 to 60 minutes of inactivity.
"According to the U.S. Environmental Protection Agency’s Energy Star program, most PCs reach the end of their ‘useful’ life due to advances in technology long before the effects of being switched on and off multiple times have a negative impact on their service life. The less time a PC is on, the longer it will last. PCs also produce heat, so turning them off reduces building cooling loads," he adds.
If you turn off your computer every night, won’t you miss out on anti-virus updates, which are installed early in the morning?
"There’s always some risk when a computer has been left off for more than a week, so it’s a good idea to activate your anti-virus update as soon as you can, and then update your operating system," Wilkinson says.
These are great tips for personal computers. But what about network servers and multi-user workstations? How can they be more "green"?
"All computers can be multi-user workstations," Wilkinson says, "so the usual power-saving steps would apply, whether the computer is operated by one person or a hundred people. Servers are machines that are connected together as a shared computing resource for many people, so by their nature they usually need to be on 24/7. Administrators can ‘go green’ by making sure they purchase servers appropriate for the task.
"Another way administrators can save energy is to use ‘virtual servers’ to replace stand-alone machines. Virtual servers are storage and computation areas that all share space on one computer, instead of sitting on separate machines requiring their own source of electricity. OIT Lab Services has been using virtual servers for years to reduce the number of computers needed," Wilkinson says.
For more ways to save energy, visit the Switch Your Thinking Web site, http://www.utk.edu/features/switch/index.shtml