Comments on: FAQ: 21st-century guide to indoor lighting

How many inventions does it take to change a lightbulb for good? We consider the pros and cons of old and new tech.

[woo37830]

Get the science right

Someone should run articles that contain scientific information
past a scientist before it's released.

1) Incandescant bulbs aren't filled with oxygen. That burns the
filaments out! They have traces of oxygen but are filled with
argon at very low pressure usually.

2) There are no "chemical" reactions going on in a flourscent
bulb. The very low pressure mercury gas is ionized by the
voltage differential across the tube. This produces ultraviolet
light. Most of the ultraviolet light strikes the powdery lining of
the flourscent tube where it produces "flourscence" by being
absorbed by the powder and re-emitted as visible light. That's
why they call it a flourscent light! It flouresces! No chemical
changes, just electrons being captured and changing state.

[billmosby]

Thanks

Someone has to ride herd on these news cowboys. Thanks for
making the effort!

[migswell]

chemical reaction.

"The very low pressure mercury gas is ionized by the voltage differential across the tube. This produces ultraviolet light. Most of the ultraviolet light strikes the powdery lining of the flourscent tube where it produces "flourscence" by being absorbed by the powder and re-emitted as visible light. That's why they call it a flourscent light! It flouresces! No chemical changes, just electrons being captured and changing state." - I believe you are describing a type of chemical reaction.

[mdjacobson]

incandescent bulbs EXCLUDE oxygen

You got the basis for the incandescent bulb backwards - the trick
Edison required to make them work was to exclude oxygen. They
hold a vacuum or an inert gas such as nitrogen or argon.

[stevenmusil]

Thank you

The error has been corrected.

[globalview99]

Guide to Indoor Lighting

What about the health effects of CFL's.

I've read some awful things about CFL's in connection with health hazard, e.g., radiation of a variety of harmful rays as well as harmful effects of artificial light on your body which according to certain studies by a Dr John Ott, natural light is needed and the incandescent is fairly close whereas the CFL (even the new and improved versions) give appearance of near natural but fall way short.

[bigduke]

Dr. Ott

I believe that his company sells some form of these lamps with the supposed property of duplicating solar light.

Our house is using some form of gas discharge fluorescent lamps in every fixture. The only hot filaments are in the microwave, oven and fridge. Oh, we do have a movie light that is quartz iodine. 99.9% of our light is green.

[Bear12291959]

LEDs waste less energy than incandescents but more than CFLs.

The author states "LEDs waste less energy than incandescents but more than CFLs." How can this be, if CFLs use approximately 1/3 the electricity of an incandescent bulb and "LED lights generally use one-tenth the energy of an incandescent bulb"?

Is the author comparing apples (LEDs left on 24 hours/day) to oranges (CFLs turned off most of the time)? If an LED uses 1/10th the energy of an incandescent, shouldn't a 60 watt output LED use roughly 1/3 the electricity of a comparable CFL?

[BrandonEubanks]

The author is right

LED's are in general more efficient than CFL's but, the way they are
used will determine the true efficiency. This is just a fact of the
technology used. They author's statement should indicate that
LED's use 1/10 th of the light to output the same amount of light
as an incandesent while a CFL uses 1/3 to output the same amount
of light. This would make LED's more efficient.

[guinnessgulper]

No, it's just complicated

Some LEDs are more efficient than some flourescents, but not all. This article and table gives you all the gory details:
http://en.wikipedia.org/wiki/Luminous_efficacy

[summershoe]

combining LEDs to make white

When white LEDs first came out they were just blue LEDs with a phospher coating. It didn't take long for them to start to get a blue color to them. The author implies they are now made out of different colored LEDs but still get a blue hue? That doesn't sound right. Plus, if you have a red, a green, and a blue LED, why do you need a yellow one to make white?

[baisa]

Has the level of science dropped to this level???

Incandescent bulbs don't "trap oxygen outside" -- how can you "trap" something outside??? The most accurate and clear way to describe them is that they employ a partial vacuum inside the bulb to exclude oxygen, so the tungsten filament can glow without burning. This was science I learned in junior high school, I'm sure. Is the general level of scientific literacy now so low that some ackward utterly dumbed-down description of a simple concept needs to be supplied? I mean, after all, this is a *tech* news site -- even if the average American is scientifically illiterate <shudder> can't we at least assume scientific literacy here? Or is the issue the authors, not the audience...???

[k2dave]

Re: Has the level of science dropped to this level???

Ok the 3rd time is a charm, while early bulbs did use a vacuum to prevent the filament from burning, modern bulbs use a inert gas.

[c.v.parker]

Inacuracies

Several incorrect statements have already been noted by others, here is an additional one.

The amount of energy cosumed by the LEDs in a Microwave oven over several years would probably be about ten percent of that required to cook a casserole. The statement in the article was completely ambiguous.

[fshattuck]

Correct the correction please

Oxygen is not trapped outside; an inert gas is substituted which allows the tungsten filament to glow rather than burn out. The earliest light bulbs used a partial vacuum; hense the rather spectacular failures of early bulbs. Halogen bulbs are vacuumed and gasses such as krypton, nitrogen and hydrogen bromide are added to the capsule under pressure.

[migswell]

led's are more efficient

hands down.

[James Anderson Merritt]

My LED pros and cons

I should start by saying that I own two LED bulbs, and spent around $70 for the pair (taxes and shipping/handling included). I got the most powerful bulbs I could find, so ended up paying a hefty premium over the $15 that is mentioned in the article. At present, you don't get much brightness for $15.

PROS:

* Even at the horrendous purchase price I paid, and assuming that electricity costs stay the same or increase over the next couple of decades, the energy savings over the estimated 60,000 hour lifetimes of the lamps will net me at least several hundred dollars that I wouldn't have had in my pocket, had I used incandescent bulbs instead.

* The LED lamps run remarkably cool. I don't have to worry about leaving them on for long periods by mistake, putting them in proximity to flammable materials, the cat knocking them over, touching them inadvertently, etc.

* I can leave the lamps on all day and night (though I usually don't), and still consume less energy than leaving similarly bright incandescent lamps on for just an hour or so. So far, I have been using only one lamp at a time, and have already seen a significant drop in my household's daily average kWh consumption. It will be interesting to see how this translates into savings on my utility bill.

CONS:

* The brighter lamps available to me only seem to come in the "cool" color temperature range, which makes them seem much like traditional fluorescents (without the buzz of faulty button exciters or the "strobe effect"). I'd like to try some "warmer" light, but the ones I can find so far only seem bright enough to use as nightlights or accent lighting.

* Even the brightest lamps I can easily find are not that bright. The "spotlights" and "floodlights" seem comparable to 50-60 watt incandescents, maybe 75 watts at best. I'd have no problem spending $20-30 to get a direct LED replacement (in brightness and color temperature) for a 100 or 150 watt incandescent. They just don't seem to be available. To get decent overall brightness, you must use multiple bulbs.

* In my limited experience, the advertising material and package labeling for LED bulbs does not give sufficient information to do an "apples-to-apples" comparison between incandescent, CFL, and LED prior to actual use. I have two C-Crane bulbs, the CC Vivid+ and the CC Vivid Spotlight Par 38, purchased from two different retailers. The Vivid+ is allegedly much brighter than the CC Vivid 2, and the spotlight 3 times brighter than the Vivid+, judging only by the posted lumen ratings for the three bulbs. On C-Crane's website, they compare the dimmest of the three, the Vivid 2, with a 60 watt incandescent, for purposes of calculating lifetime costs of LED bulbs vs. those of incandescents. But in my experience, the Vivid+ provides as much light as I am used to getting from a 25-40 watt incandescent bulb, while the spotlight, as I said above, provides light that seems roughly equivalent to what I get from 50-75 watt incandescents. So there is no way that you would use a Vivid 2 in the same context as a 60 watt incandescent -- unless the 60w was major overkill for the application. The advertised cost comparison is not at all apples to apples. Perhaps you might replace a 60 watt bulb in a desk lamp with a Vivid 2 and be satisfied. But in that case, you could also replace the 60 watt bulb with a 25 watt incandescent bulb and be happy. Even talking about a limited, "reading lamp" application, I think that's a stretch.

* Not all available LED bulbs are recommended for use with dimmers, and even the dimmer-capable ones definitely don't work with three-way bulb step switches (that is, they do work, but not any more satisfactorily than a regular bulb works in a 3-way socket). Also, because even the brightest bulbs aren't that bright to begin with, it often makes little sense to use a "dimmer," unless you are controlling a bank of such bulbs.

The trick seems to be finding an application where the amount of light given off by the LED bulbs is appropriate for the intended purpose: then, you can start to figure cost savings over incandescents by doing apples-to-apples comparisons. I currently have a spotlight mounted in a desk lamp, aimed at the white wall behind me. This dimly lights my living room via light reflected from the wall, and makes the room bright enough to read by, if you are sitting in the corner of the room where the lamp is. By swiveling the desk lamp to point directly at something in the room, you can illuminate that thing fairly well, at the cost of plunging the rest of the room into semi-darkness. I'd love to be able to switch out the 3-way floor lamp bulb with something that would give equiavlent light, but the Par 38 spotlight bulb won't cut it. So I use the incandescent floor lamp in the early evening, when the rest of the family is up, and switch to the LED later on, after everyone else has gone to bed, if I have late night TV watching or reading to do. Even so, as I said, using this one bulb in this way has cut my average daily household usage by a significant amount, about 5% so far.

I hope the material above has been helpful. If anyone knows of a supplier for true incandescent replacement LED bulbs at reasonable prices (reasonable by LED standards, at least :-), please post here!

[sjkx]

thanks!

Just wanted to thank you for the useful feedback even though I get
the feeling 99% of followup comments here never get noticed by
the original posted, especially after a day or two goes by.

[Wesley_Mouch]

I'm so dissapointed...

***? 19 comments and nobody has bashed President Bush or mentioned the war in Iraq yet?

Here I was all set to rebut the evirowhacks with my "green is the new red" diatribe, and all I get is an on-topic technical discussion and definitions of chemistry.

Fine, I'll stir the stew: A chemist is a failed physicist!

There, I said it.

[Wesley_Mouch]

not to mention Disappointed.

My fingers are dyslexic when my brain hasn't had coffee.

[Babak Rezai]

LOTS OF INFO, why yellow is used in white LEDS

http://en.wikipedia.org/wiki/LED_lamp