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shallowdeep -> RE: To the whiners about incandescent light bulbs (1/31/2011 2:33:42 AM)
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quote:
ORIGINAL: BenevolentM
So all of this interest in fluorescent lighting is the product of what seems logical to engineers and scientists.
Ah, nice to be appreciated!
Just some late thoughts and comments in case anyone's still interested:
I think there's a strong and fairly understandable naturally tendency for consumers to weight upfront costs heavily while discounting small, distributed costs that can be deferred. That makes things like CFLs and halogens a hard sell, even without objections to the light quality. But, looking at it from a policy perspective, there honestly is a compelling reason to make a shift. Individually, it may not seem like much, but the gross inefficiency of traditional incandescent bulbs quickly adds up on a large scale. And government inefficiency is bad, right? :)
Looking at the US, the country used 511 billion kWhrs of electrical energy for lighting in 2009 according to the EIA. Some of that is already for relatively efficient lighting, but CFLs only had around 17% socket saturation in 2008 according to the DOE (pdf) and that figure is an even lower 11% in residences. That means there's still a huge amount of room for improved efficiency. The DOE thinks 190 billion kWhrs could be saved. Using the national average rate for electricity of 9.83 cents/kWhr, that's $18.7 billion dollars saved per year. At average residential rates (where most of the saving opportunity is) that would be $21.9 billion. It's also the output of 24 1 GW nuclear reactors. That strikes me as a fair bit of money, energy, and infrastructure. Taking advantage of savings on that scale seems hard to argue with.
There are some situations where the savings from a CFL are diminished or non-existent (e.g. if you use electric heating during winter, or if it's a light you don't turn on frequently for more than 5-15 minutes at a time), but the return on investment is usually quite rapid. Bulb costs are quite small relative to energy costs.
The mercury in CFLs isn't wonderful, but something that's often overlooked is that incandescent bulbs aren't exactly mercury free, either. If you get your energy from the typical US grid mix, they may actually be worse; burning coal releases mercury into the atmosphere. This fact sheet (pdf) explains some more, and calculates the environmental mercury contribution from a CFL tossed into a landfill to actually be around 3.4 times less than that from using incandescents instead. Plus, recycling the bulbs really isn't that hard, at least around here.
But…
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ORIGINAL: kdsub
The new energy efficient bulbs start slow and, at least to my eyes, watt for watt are nowhere as bright even when they build to maximum light output. My old eyes need incandescent light.
and
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ORIGINAL: BenevolentM
The quality of light produced by florescent bulbs is just awful and continues to be awful.
The light is different. But perception of quality is purely subjective. My sister hates it; I happen to prefer it, especially for reading. According to at least one survey (pdf, see p. 10), I'm actually in the more typical group. 82% of 18-34 year olds prefer CFLs or see no difference. Interestingly, that figure does drop down to only 76% of 55+ year olds, though.
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ORIGINAL: BenevolentM
Our sun is not blue. It is illogical to use lighting that fails to mimic the color spectrum of our sun. Our visual system is not adapted to the sort of light produced by florescent lighting.
While I'm perfectly willing to accept that there are some people who don't like CFL lighting, this argument is absolute bunk. If you consider CFLs blue, then I have a surprise for you – sunlight actually is blue too. Tungsten filaments, like the sun, are basically black body radiators, but because the filament is much cooler than the sun, it produces (confusingly enough) a significantly "warmer" visible spectrum concentrated toward red and infrared wavelengths. The color temperature of incandescents is around 2700K - 3200K. Summer sunlight is around 5500K, which is much more blue. If Rayleigh scattered diffuse skylight is added back in, the difference is even more pronounced. In fact, blue filters are needed if using tungsten lights to mimic daylight in films. And, contrary to your belief, fluorescents are now used professionally for things like TV and film lighting, in part because they come in a wide range of color temperatures and can be used more easily to emulate daylight. Don't take my word for it, though. Feel free to read a book.
What is true is that fluorescent sources tend to have more "spiky" spectra with spectral peaks at the emission wavelengths of their mercury vapor and their phosphor mixture. I've attached an image showing the (normalized) spectra of daylight, a fluorescent bulb, and an incandescent bulb. Tungsten clearly doesn't mimic sunlight well and, in many respects, the fluorescent is actually a better objective match for daylight. Newer phosphor mixtures are helping to further smooth out the peaks like those seen in the image, but they still do exist. Neither type of bulb is a perfect match. It's fine if you object to CFL light, but be aware that what you happen to like is an artificial red light, not natural daylight. So don't blame evolution. :)
Incidentally, as Termin8or pointed out, LEDs have the same spectral spikiness. Almost all white LED lights actually use a blue/violet InGaN LED source, then rely on a phosphor mixture to spread that around – just like a fluorescent uses the UV light from the mercury vapor to excite phosphors and produce other colors.
On the topic of LEDs:
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ORIGINAL: kdsub
The 80 to 90 percent power reduction and lumens values are very misleading. LEDs have a very focused light compared to incandescent light… the power rating savings are not nearly as great when comparative light and light spread is taken into consideration. To match the spread you must have multiple LED's.
Um, no. Lumens are a unit of luminous flux, not intensity. As such, they measure the total amount of light coming out of a bulb, regardless of how that light is distributed. If anything, directional LEDs actually get short shrift in a lumens to lumens comparison when being used in a directional capacity, like a downlight. An omnidirectional incandescent bulb will lose a considerable percentage of its light in such a fixture, but an LED won't. The end result is an LED will actually produce a higher intensity light in the room when compared to an equivalent lumen incandescent. If you want omnidirectional light, there are now LED bulbs that fit that bill.
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ORIGINAL: kdsub
Watt for watt the led's can't compare YET to the overall unfocused light of an incandescent bulb. They will with time…right now the quality of light for the money is in question.
I'm not quite sure what you mean. For a given watt, currently available commercial white LED bulbs will produce around four times as much light as an incandescent. In that respect they already trounce incandescents without question and are on par with CFLs, if still lagging better ones a little bit. As with CFLs, the quality of the light is subjective. I've bought several over the past few years and, honestly, I wouldn't have recommended them to anyone who really loved incandescents. Until recently, at any rate. I bought some new Philips bulbs earlier this month that at least come close. They're a bit on the pricy side ($40 for a 60W equivalent, $22 for a 40W equivalent) but they managed to pass muster with my fluorescent-loathing sister. First time that's happened. The 60W equivalent version is available on Home Depot's site. It will take around 6500 hours of use to break even with my electric rates, but for my frequently used bulb that should only take a few years.
You're right that LEDs should keep improving, though. The DOE has targeted commercial 160 lm/W by 2025, and that efficacy has already been demonstrated in labs. Droop still seems to keeping LEDs out of bulbs much beyond the 60W equivalent range for now, but the DOE's L-Prize entrants already threaten to make my latest 64 lm/W bulb look bad soon. So I can understand waiting a bit. I guess I personally sort of enjoy being an early adopter, though…
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ORIGINAL: kdsub
I can buy a 60 watt incandescent bulb for 2 bucks that will have a 20K life span...now do the math.
Long-life incandescent bulbs do exist, but they make a tradeoff that generally makes them even less cost-effective than a regular incandescent. To prolong life, they reduce the temperature of the filament. At the lower temperature, the bulb becomes even less efficient than an already abysmal incandescent at producing radiation in the visible spectrum. So, you need either more bulbs or higher wattage ones to maintain the same light output. The cost of that additional power tends to more than offset bulb savings, which is why most bulbs use hotter filaments that only last 750 - 1000 hours. If it's a big hassle or expense to change the bulbs, long-life bulbs might make sense – but there's a reason that sort of bulb is relegated to a niche market. And, as has been pointed out, the energy costs make a CFL (or even an LED) more cost-effective over time.
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ORIGINAL: DomKen
Here's a 60 watt equivalent LED with a 50k hour lifespan that costs only $23
http://www.ledbulb.com/A19-LED-Lamp-p/a19-e26-5.2w-f.htm
Just a quick note, 450-550 lumens is more like a 40W equivalent. 900 lumens is more typical of a 60W incandescent.
[image]local://upfiles/324704/7242F13F4A1C4242ABC912828CAF4251.gif[/image]
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