 |
 |
|
 |
 |
 |
 |
 |
 |
 |
 |
| |
REPP
1612 K Street, NW
Suite 202
Washington, DC 20006
|
|
 |
|
|
|
|
Ask the Expert: What difference does leaving one light bulb on make?
By Ken Sheinkopf
 |
| Many compact fluorescent light bulbs now carry the
Energy Star label. These bulbs last up to 10,000 and
save $25–$45 over the life of the bulb. |
Q: At what point is it more
efficient to leave a light on when leaving and returning to
a room, rather than turning it off? I just can't believe one
light bulb costs much to operate.
A: No, it doesn't cost a whole lot of energy to have
a light bulb turned on. A 100-watt bulb, in a home paying about
9 cents per kilowatt-hour, costs about a penny an hour to operate.
But leave that bulb on needlessly for 12 hours a day and you
just spent an extra $3.50 or so a month for that bulb—about
$40 per year. And how many light bulbs do you have in your house
right now? Count them—I'll bet your surprised at how many
there are. That penny an hour for one bulb can quickly become
hundreds of dollars per year for all the bulbs in your home.
As for the economics of turning lights on and off, I went back
to energy expert Danny Parker of the Florida Solar Energy Center
and asked him what he thought. When you're talking about a standard
incandescent bulb, he pointed out that turning it on and off
doesn't shorten the life of its filament significantly, so there
really is no reason to leave it on unnecessarily. If you're
talking about fluorescent tubes, though, turning them on does
age the filaments significantly so if you plan to restart a
fluorescent in a minute or so, leave it on. Note that this is
not a recommendation to leave fluorescent bulbs burning constantly,
just a note that if you're going to not need one after a few
minutes, turn it off.
In general, it is never a good idea to leave lights on when
they are not needed.
******************
More information on Energy
Star Lighting.
Bibliography:
Editor's Notes: Ken Sheinkopf is Associate Director of the Florida Solar Energy Center. Write to him at 1679 Clearlake Road, Cocoa, FL 32922, or e-mail Sheinkopf@fsec.ucf.edu
Mr. Sheinkopf cannot answer every question personally. Check back here at www.crest.org to see if he's already answered your question.
Photo credit: NREL PIX number 07737
Title: Energy Star-compliant lighting
Caption: Many compact fluorescent light bulbs now carry the Energy Star label. These bulbs last u to 10,000 and save $25-$45 over the life of the bulb.
Credit:D&R Int., LTD
Publications: Clean energy for the 21st century (DOE/GO-10099-911,
December 1999)
|
|
|
