$creen $avers ¢ost $$$$
When CRTs (cathode ray tubes) were the only choice, image burn in on the
87 watts (screen saver minus standby) ÷ 1000 = 0.087 kw
0.087 kw x 3 hours per day x 5 days per week = 1.305 kilowatt hour
(kwh) / work week
tube generated a whole new art form we now call screen savers. We all got 1.305 kwh / work week x 52 weeks in a year = 67.86 kwh / year
hooked with those dashes of color in our drab offices and now can’t seem
to do without them. They are however, no longer needed in our brave 67.86 kwh / year x $0.26 per kilowatt hour = $17.64 saved /
year / computer
new world of LCDs (aka flat screens or liquid crystal displays) and Energy
Star computers, since they automatically drop into a lower power standby
mode… if we let them.
TOTAL SAVED if all 9,000 networked
computers at UH didn’t do screen savers
=
$158,792.40
So here’s the rub: a screen saver in all its colorful
wonder keeps the CPU (central processor unit or the I’m pretty fond of my screen saver fish tank, too, but the energy we can save
brains of the computer) running and keeps the LCD with this very simple change can add up to be a big difference. If we all work
panel running full tilt. If a screen saver is running, towards sweeping up those nick-
all the power saving features of that computer is els and dimes in energy savings,
disabled. It’s almost like leaving your house lights burning all day long. pretty soon we’re talking some
real money here.
Using a typical Dell 17” LCD monitor and a Dell Optiplex 755 desktop com-
puter for our example (both are energy star and were measured with a Kill- Need help with power saving
a-Watt meter): and figuring 3 hours a day when computers are otherwise settings for your computer? ITS
idle, we can calculate: has some instructions at www.
hawaii.edu/askus/926/
CPU Monitor TOTAL
Mode Glossary
Power Usage Power Usage Power Usage
CPU Central Processing Unit, the brain of the computer that runs the programs. A screen
saver is a program and, thusly, the CPU won’t go to sleep because it’s running the
Standby 5 watts 2 watts 7 watts screen saver.
Screen saver 64 watts 30 watts 94 watts CRT Cathode Ray Tube, older style monitor with a big glass tube as the display. Since this
monitor has to “paint” the screen with an electron beam to light up phosphors on the
screen, it uses quite a bit of energy as part of this process.
Differences 59 watts 28 watts 87 watts
LCD Liquid Crystal Display is the new monitor technology that uses low power semicon-
ductor technology to turn on/off little bits of the screen to make images. These “flat
screen monitors” use dramatically less energy and have the added advantage of not
“burning in.”
“Burning In” On old CRT monitors, leaving the same image on the screen for long periods of time
would permanently “burn” the phosphors on the screen leaving a “sun burn” like pat-
tern that you could see even if the monitor was turned off.
http://www.manoa.hawaii.edu/green