Noah Buhayar and Laurie Ramroth are fellows at Rocky Mountain Institute.
You’ve taken the plunge. You’ve replaced all those incandescent bulbs in your house with energy-saving compact fluorescent lamps (CFLs). You’ve even gone as far as installing dimmable CFLs for the few places where you’d like to be able to control the intensity of the light.
But, lo and behold, some of those new lights are burning out sooner than the manufacturer claims they should. What gives? Aren’t CFLs supposed to last 10 times longer than the cheaper incandescents?
Here’s some straightforward information about how you can get the most out of your CFLs, and why you’re probably still saving emissions and money even if you don’t get all the advertised hours out of each lamp.
“Operating cycle” and CFL life
The life of your CFL depends on how often you turn it on and off, and how long you leave it on. In engineering lingo, this is called the lamp’s “operating cycle.”
Operating cycles can vary for practical reasons. Think of the CFL in your garage versus the one in your bedroom. The one in your garage probably stays on for only a few minutes: when you open the garage door, or when you go out at night to put something in your vehicle. The CFL in your bedroom, however, probably stays on longer: when you read or watch TV in bed.
CFLs usually fail when the electrode’s emissive coating (the part of the bulb that emits electrons into the tube to create and maintain an electrical arc) evaporates. This loss of coating occurs slowly during operation, but is accelerated each time the lamp is turned on, and the electrode is bombarded with mercury ions.
That means the more frequently you turn your CFLs on and off, the shorter its operating cycle, and the shorter its life.
Greenhouse gas emissions
The good news is that even if you’re operating your CFLs for short periods of time, you’re still putting less greenhouse gas into the atmosphere than you would have operating that old incandescent in the same manner.
A group of researchers at RMI recently studied the emissions associated with manufacturing, distributing, operating, and disposing of both incandescent and CFLs.
They found that even if a CFL’s average operating cycle was reduced from 1 hour to 5 minutes, greenhouse gas emissions were still lower — 63.4 percent lower — than those of an incandescent. That difference takes into account the shortened life of the CFL (and the fact that another one would have to be assembled, shipped, and purchased at a store).
Getting your money’s worth
Of course, saving greenhouse gas emissions might be a small consolation if you’re buying CFLs more often than you think you should have to, and watching the up-front costs add up.
Remember, though, that CFLs save you money in 2 ways: (1) They last longer than incandescent bulbs, and (2) They use less electricity to provide the same amount of light.
In our emissions analysis, RMI’s researchers also looked at average payback time for CFLs under different operating conditions and at different electricity costs.
Even with extremely cheap electricity ($0.0492 per kilowatt-hour) and a drastically reduced life (1,500 hours on a lamp rated for 10,000 hours), the CFL still paid back its extra retail cost before failing. This held true even if the retail price for a 23-watt lamp varied from $1.65 to $5.50.
Taking it to the next level
The bottom line: Even if you’re replacing your CFLs more often than you think you should have to, you’re still coming out ahead in terms of reducing emissions, and are most likely saving money.
Next time you screw in a CFL, though, see if you can make it last longer by changing its operating cycle. Monitor your energy bill and see how quickly you can get a return on investment. And know that the more efficiently you use your new lights, the more greenhouse gas you’ll be keeping out of the atmosphere.
For more visit Source:[green.yahoo]
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