January 07, 2012
Lighting Trade-Offs with LEDs, CFLs, Halogens
Due to both technological advances and regulatory and economic drives toward greater energy efficiency decisions over light bulb choices have gotten much more complex - unless you just ignore the complexity and grab something off the shelf. But if you like the maximize the quality of your light bulb buying decisions then a review on light bulbs by Bob Tedeschi in the New York Times is a good place to start.
The quality of L.E.D. light, even the “soft white” types, is noticeably cooler than that of halogens or C.F.L.’s. And because most L.E.D.’s are unidirectional, they work well for recessed lights or lamps that spotlight artwork. But this single-focus nature is a problem for standard shaded lamps. The packaging of Sylvania’s Ultra A-Line L.E.D. suggests that it’s suitable for a shaded lamp, but when I tried it in a lamp in my living room, the top half was lit, while the bottom saw little light.
However, Sylvania will release an omnidirectional L.E.D. this winter, and two manufacturers are now making them. When I tried them — G.E.’s Energy Smart L.E.D. and the Philips AmbientLED — they lighted up both the top and bottom of my lamp. The Philips bulb was softer than G.E.’s — so much so that I now have two of them gracing my living room.
LEDs, while still expensive, have come down far enough in price that their life expectancies (20+ years in most cases) make them an attractive choice. It is always good to find more areas of one's life where one can basically deal with a problem once and then not think about it for a long time.
the article is not a sales job for uniform use of LEDs. He does a good job of explaining the trade-offs for different rooms of the house and purposes. Worth a read if you want to make smarter lighting decisions.
One interesting factoid from the article brings up a new way (at least I haven't thought of it) to save energy: rejuvenate eyes.
“Fifty-year-olds need twice as much light to read something as well as a 20-year-old,” Mr. Bernecker said. “It’s a sad story.”
Think about it. If we could replace aged lens and send in stem cells and gene therapies to repair eyes we would have in electric lighting costs. Plus, we've save even more in costs of optometry and eye glasses. The gain in convenience (no more "where are my glasses") would be considerable as well.
I don't like the CFL's because of the Mercury used in them. If the LED's get cheap enough (and the light is sufficient), I would like to change to them because they last much longer than incandescent bulbs.
the loss of light sensitivity stems from the loss of Rhodopsin
Until the designers of LED bulbs pay as much attention to RFI emissions as they do to light spectrum and distribution, they're still going to have issues.
I bought an Edison-base LED lamp which kills FM radio reception at 5 paces. That's some serious RFI emissions.
When I bought my first CFL's, they said, "Sure, they're more expensive, but they'll last years." They were dead within months, in many cases without having been used more than a few minutes. This was due to being in wiring setups with multiple illuminated switches; The trickle current necessary to illuminate the switches meant nothing to incandescents, but caused the ballasts on the CFL's to repeatedly fire, (At night you could see the tiny flashes every minute or so.) wearing them out. When they weren't even turned on. Put them in the basement, figured I'd never have to replace them. But I did, with incandescents.
I'll believe the 20 year lifetime of LED bulbs, if we're both alive 20 years from now. I've seen too many of the LED traffic lights with randomly dark pixels to trust the current implementations. Incandescent is a mature technology. LED is not.
LEDs have infant mortality issues (which is why some traffic lights have dead sub-strings), but once burned in they're good for tens of thousands of hours.
Do I care if it's the LED or the driver circuit that dies? I'm not screwing an LED into my table lamp, I'm screwing in a complete system, and that's what has to last 20 years. Heck, that's what's died in the traffic lights I've seen, based on the fact that some of them have *flashing* strings of LEDs.
You're still asking me to buy a more expensive light based on a 20 year life that's extrapolated based on inadequate experience. I simply have no reason to put any faith in that estimated lifespan.
RFI: I'm guessing Radio Frequency Interference?
My wife and I are very happy with the new Philips 800 lumen LED 2700deg warm light
that we are using in an overhead dining table lamp. 12.5 watts is what really does it for me, since we are off the grid and every watt counts.
I haven't heard any RFI on my FM yet, maybe I have to find the right frequency.