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April 11, 2006



This savings plan does not work for me. For reasons I do not understand, the compact fluorescent bulbs do NOT last anything like 10,000 hours. I replace them as often as I replace the incadescent bulbs. Which also do not last 2,000 hours. I suspect that there is something "rough" about my electric supply, but I don't know that.


Then there are folks like me. There are parts of my home where I want to leave the lights on almost all the time. Fluorescent lamps make that easy and cheap. Because I leave the lights on all the time, there's probably no real energy savings, but I get a tremendous improvement in convenience.


Pheon -- I feel your pain. Frankly, my cheap bulbs only seem to last about 12 months, which is like 4000 hours the way I use them. To take an extreme case -- if your fluorescent bulb lasts only 2000 or so hours, and the incandescent bulbs are completely free, the fluorescent still has an NPV of $18.13 -- not quite as dramatic but still a winner. The key is that 2000 hours of saving 75% on wattage is a much bigger total savings now than it was 5 years ago!

Windy -- I'm certainly spendthrift with fluorescent lights in certain parts of my house. The incentive to go around the house turning the lights off is certainly dampened, isn't it? But knowing that it's only a few 9-watt bulbs makes me smile every night when I go to sleep.


Had me worried... The link to 1000bulbs doesn't have the 23-watt compact flourescent you are talking about. It starts off with several 13-watts, which equate to 60 watts. But they equate 28w to 105w incandescent, so it looks like you have it right.

Good spreadsheet.


Came here from VP's Dynamist blog. Beware, I bought a
bunch of "dollar-store" compact flourescents last summer
and the color was simply horrid. But the good major-
branded ones have been pretty good on color, considering
that they were flourescent lamps.


Mycroft - I don't follow your logic. If the incandescent bulbs and the fluorescent bulbs both last 2000 hours --- which is about what I suspect, though I have only just started keeping track of when I change them --- and the fluorescent costs me several dollars more, how can it have an NPV of $18.13?

(Mycroft replies) Pheon -- those 2000 hours of light use many, MANY fewer kilowatt-hours of energy, at 13.5 cents each. Saving 75% on power is where the main savings come from, not the small amount of saving $ on light bulbs.

Dim Bulb

(Found you via Virginia Postrel, who is famous for reminding us that beauty is worth something, too.)

Lighting is one of the cheapest, easiest ways to redecorate your home.

Problem: Fluorescent bulbs look awful. They make a home look like a 7-11. While currently expensive, LEDs last even longer, are even more efficient, and are available in small form factors such as night lights. Also, I find they look less awful.

Another option: I have had excellent results using incandescent and halogen bulbs on dimmers. Unlike fluors, dimmable lights are beautiful. Decorators often counsel putting dimmers in every room. I have done so, and find that I rarely want/need the lights at 100%. I often run them at 50% or so, which (a) uses less electricity, (b) imparts a warm color, and (c) makes the bulbs last much longer.


Dim Bulb:
Unfortunately incandescents on dimmers don't really save very much energy. If you adjust a incandescent to be, say, 50% as bright, it is still using 80-85% of the energy as running on full. What happens when you dim them is that you shift the light output into the infra-red, so they are generating more heat, instead of light. Their inefficiency goes up more as you dim them more.

Do a web search on "kill-a-watt meter".

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