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Savings from Compact Fluorescent Lights (CFLs)
Can a light bulb save $9/year and last 6.85 years?
Yes. This is a conservative estimate of average savings. More money can be saved in states with expensive electricity. ZFacts takes account of all the real-world factors others leave out.
For over 50 years businesses have been saving lots of money by lighting with fluorescent bulbs. At home, they were never popular because they made people and colors look funny, they hummed, they flickered, and you couldn't screw them in.
All that has changed, and you can now save almost as much as businesses do. Screw-in compact fluorescents are here. They are not quite as cheap per Watt as the big ugly ones that hum. But they are tiny, quiet, cool, and they last and last.
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Q: What missing factors does ZFacts take into account?
1. Reduced heating from CFLs in the winter.
2. The dimming of CFLs over their life.
3. The need to spend more up front.
Q: What are the CFLs compared with?
They compared with normal (incandescent) GE Soft White bulbs with a life of 1000h and a cost of 50¢.
Q: How does reduced heating in winter reduce savings?
CFLs are cooler to the touch--they can't burn you. This is because the waste a lot less energy as heat. But in the winter, this heat allows your furnace to run a little less, and this saves you some money. Of course in the summer, it makes your're air conditioner run more. The result is CFLs save less than it seems in winter and more in summer. ZFacts has made a very conservative estimate that the net result is a 25% reduction in the dollar value of energy savings.
Q: How does dimming reduce savings?
CFL bulbs are normally compared on the basis of their inital "lumen" light output. But over their life, they dim a bit more than normal bulbs. ZFacts makes savings comparisons by comparing two bulbs, CFL and normal, with the same average lifetime brightness.
Q: How does the up-front purchase reduce the savings?
CFLs last a very long time. ZFacts assumes a 1000 hour bulb will last about 7 years. With short-life bulbs, you could delay part of your purchase and earn interest (15% is assumed) on your money. Of course, not having to shop and replace 10 incandescent bulbs is a big plus for CFLs, but ZFacts ignores that.
Q: Do CFLs really last 10,000 hours?
The NLPIR tested hundreds of bulbs and in all but one test, they lived up to their rated hours. GE's 10,000 bulbs actually averaged 15,000. But these tests run them 3 hours on and 20 minutes off. Here are their result for shorter on times.
| On Time | Bulb Life |
| 1 hour | 8,000 hours |
| 15 minutes | 3,000 hours |
| 5 minutes | 1,500 hours |
It doesn't pay to use a CFL where it's only on for 5 minutes at a time. In fact you shouldn't turn one off for just 5 minutes--it will cost about 1/100 of a cent more in shorter bulb life than you save in energy. Nothing to worry about, so just turn them on and off as you would a regular bulb.
Q: What's this about gallons of gasoline?
Most of the energy saved will be from coal plants that produce electricity. All of the fossil energy saved (but not the nuclear or hydro) has been converted to an amount of gasoline with the same energy, just to make it more understandable.
Q: What's the bottom line?
Fluorescents save a lot of money and energy except when they are used very little or for just a few minutes (about 5 or less) at a time. ZFacts had taken account of all the negative factors usually omitted, and the savings are still substantial.
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http://zfacts.com/p/423.html | 01/18/12 07:21 GMT
Modified: Sun, 09 Jul 2006 20:49:45 GMT
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