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2: The Basics of Green IT 27

address the issue of responsible computer use. By adopting conserving
practices, the University can save $300,000 to $400,000 annually.

How Much Energy Does Your Laptop Computer System
Use?
A typical desktop PC system is composed of the computer itself (the
CPU or the “box”), a monitor, and printer. Your CPU might require
approximately 100 watts of electrical power. Add 50 watts to 150 watts
for a 15–17-inch monitor, proportionately more for larger monitors. The
power requirements of conventional laser printers can be as high as 100
watts or more when printing, though much less when idling in a sleep
mode. Ink-jet printers use as little as 12 watts while printing and
5 watts while idling.
How a user operates the computer also factors into energy costs. First,
let’s take the worst-case scenario: continuous operation. Assuming you
operate a 200-watt PC system day and night every day, direct annual
electrical costs would be more than $125 (at $0.075/KWH). In contrast,
ptg
if you operate your system only during normal business hours, say
40 hours per week, the direct annual energy cost will be about $30—
plus, of course, the cost of providing additional cooling.
Considering the tremendous benefits of computer use, neither of the
preceding cost figures might seem like much, but think of what happens
when these costs are multiplied by the many thousands of computers in
use at, say, CU. The energy waste dollars add up quickly.

Energy-Efficient Desktop and Laptop Computing

Following are some tested suggestions for you to reduce your com-
puter energy consumption by 80 percent or more, while still retaining
most or all productivity and other benefits of your computer system,
including network connectivity.

Screen Savers Save No Energy
If screen-saver images appear on your monitor for more than five min-
utes, you are wasting energy! Screen-saver programs might save the
phosphors in your monitor screen, but this is not actually a concern with
newer monitors, especially LCD screens. And screen savers do not save
any energy. A screen saver that displays moving images causes your
monitor to consume as much electricity as it does when in active use.