Why Sleep
Computers
and monitors, especially CRT monitors, are significant consumers of
electricity. On our campus, there are as many as 20,000 computers, most
of which have monitors. Anytime this equipment is left on when not in
use, it wastes electricity. Green
Practices hopes to
educate the campus community about saving energy through better computer
and monitor management.
A 17-inch monitor uses 100 Watts of electricity
on average, which is roughly equal to an incandescent light bulb. While
100 Watts is not an enormous amount of electricity, it does become significant
if a monitor is left on all the time. Since electricity is measured
and billed in kilowatt-hours, if you use a 100 Watt monitor for one
hour, you use 0.1 kilowatt-hours of electricity. If left on all the
time (8760 hours per year) the monitor would use 876 kWh. We pay an
average of 5 cents per kilowatt-hour for electricity; therefore the
monitor's energy consumption would cost approximately $44 for one year.
One easy and obvious way to reduce the amount
of electricity wasted is to switch off the monitor when you leave for
lunch or go home for the day. However, most operating systems have a
simple setting that makes your computer turn off the monitor for you,
after it has not been used for a set period of time. We have found that
many monitors do not have the energy saver enabled, and those that do
have it set for 30 minutes, while we recommend using a setting of 10
minutes. By decreasing the time you keep your monitor turned on, you
increase the energy saved. On average, allowing your monitor to go
to sleep reduces energy use of your desktop computer by 72%! You
can verify or activate your sleep time setting by following these instructions.
Changing your power management settings by even
just a few minutes has an impact on how much energy you save. While
the amount may be small for your computer, perhaps only $5 per year,
when you consider the 20,000 monitors on campus that would be $100,000
saved overall. Carnegie Mellon can then use that money toward great
things on campus, such as speakers, events, or other green initiatives.
Also remember that using less energy means you are saving resources
and helping to reduce air pollution.
If you have any questions or comments about the
program, or need additional help, please send a message to
save-energy@andrew.cmu.edu.
