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LED Bulbs Save Substantial Energy

nytimes.com

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Re: LED Bulbs Save Substantial Energy

#41

Post by stan_rogers »

jerf wrote: post #40
stan_rogers wrote: post #39

Earlier quoted context omitted.

"Fluorescents and Compact fluorescents produce horrible light as a result of the phosphor coating used to create white light." That's a bit of an overgeneralisation -- there's a significant difference between the cheapo tubes and, say, an OTT tube (just one, albeit excellent, example of a full-spectrum fluorescent). The easiest, cheapest way to get a decent idea of the spectrum is to use a CD or DVD (we've all got at…

Thank you very much for the CD/DVD idea! I see five clear differently-colored copies of my local compact florescent tube in my DVD's rainbow... can you confirm that I am interpreting that correctly as five spikes and virtually nothing in between those spikes? My local incandescent lights are just a rainbow smear. Oh, awesome, I can do it to my LCD screen too and clearly see three differently-colored reflections! ...…

Why, yes. Yes I can confirm that. And I can tell you that noticing it about 25 years back, when I was doing photography professionally, saved me a metric crapload of money on special meters and so on -- but only after I had button-holed every single person I'd ever met to show them what I'd seen whether they cared or not. I truly understand the geek-out part.

Re: LED Bulbs Save Substantial Energy

#42

Post by teeja »

jackmoore wrote: post #38
anamax wrote: post #37

Their CFL lifetime numbers don't match my experience. (I typically get longer life from incandescents than CFLs.) Also, they assume that energy converted to heat is wasted. If you're heating a lit room, that's obviously not true. Yes, many forms of heat are cheaper than resistive, but if you're going to claim to be the last word, you have to account for things like that.

Heat generated by a lightbulb is near the ceiling where air is probably not being well circulated. So unless you are installing fans around the base of your bulbs to move the warm air around the room where it would be useful to the inhabitants, it is mostly wasted. This is assuming that the heat is even desirable.

Air circulation is essential to efficient and comfortable heating with any heat source. However it's done, it must be or heat will pool at the ceiling. You're right if lighting is done at ceiling level. Table lamps, though, create some convected air.

Re: LED Bulbs Save Substantial Energy

#43

Post by pmjordan »

blahedo wrote: post #36
pmjordan wrote: post #3

Now they just need to come down in price and get the spectrum right. While the fluorescent lights are already competitively priced, LED ones are still rather pricey, at about €15-20. The spectrum emitted by the pseudo-white LEDs is also unpleasant (primarily yellow + blue), the RGB ones need to become cheap enough. RGB lamps could also have some interesting extra features, like adjusting hue based on time of day, whi…

They'll probably get there eventually, but considering that CFLs are only just now starting to become legit replacements for some incandescent bulbs---the light quality in a house that went all-CFL during the first big pushes a few years back is appalling---I wouldn't hold my breath.

Except with incandescent bulbs banned in the EU, there's now a strong economic incentive to build cheap, good and efficient replacements. Mind you, I'm not sure banning them outright is the way I'd have done it. (I'd have taxed the environmental impact per amount of light emitted and lifetime)

Re: LED Bulbs Save Substantial Energy

#44

Post by pmjordan »

eru wrote: post #32
Devilboy wrote: post #29

Earlier quoted context omitted.

Really what you need to do is match the wavelenghts that our rods and cones in our eyes are most sensitive to. That should be the optimal solution in terms of energy usage.

Perhaps. But it might not be pleasant to the eye.

The 'red' cones alone can't tell the difference between orange and brick red. The idea is to stimulate all 3 types of cones and the rods in the same proportion as daylight does. RGB LEDs should have the cones covered; I wonder if the problem are the rods? Do we need 4-component LEDs?

Re: LED Bulbs Save Substantial Energy

#45

Post by eru »

pmjordan wrote: post #44
eru wrote: post #32

Earlier quoted context omitted.

Perhaps. But it might not be pleasant to the eye.

The 'red' cones alone can't tell the difference between orange and brick red. The idea is to stimulate all 3 types of cones and the rods in the same proportion as daylight does. RGB LEDs should have the cones covered; I wonder if the problem are the rods? Do we need 4-component LEDs?

I don't know if all the cells in your eye are perfectly tuned to three peeks. I expect biological systems to show some variance.

Re: LED Bulbs Save Substantial Energy

#46

Post by pmjordan »

eru wrote: post #45
pmjordan wrote: post #44

Earlier quoted context omitted.

The 'red' cones alone can't tell the difference between orange and brick red. The idea is to stimulate all 3 types of cones and the rods in the same proportion as daylight does. RGB LEDs should have the cones covered; I wonder if the problem are the rods? Do we need 4-component LEDs?

I don't know if all the cells in your eye are perfectly tuned to three peeks. I expect biological systems to show some variance.

The mechanism is chemical/physical, though, and depends on the absorption spectrum of a certain pigment molecule for each type of receptor. I strongly suspect the variance in those is likely to be tiny.

Re: LED Bulbs Save Substantial Energy

#47

Post by BearOfNH »

mieses wrote: post #16

Incandescents approximate sunlight better than LED's and most other light sources. http://exploration.vanderbilt.edu/images/news/article_main/q... The health implications should be studied. Subjectively, incandescents are more pleasant than fluorescents and LED's. Our brains might be telling us something.

How does this work with a lampshade or a wall sconce? Putting the light through some kind of filter must (?) narrow the difference between the kinds of light. In which case I've got a lot of lights that can be upgraded to LED.

I'm willing to pay the high initial cost of LED lighting, assuming the light is of good quality (brightness AND color-with-lampshade) and the long-term savings are real. I suspect most HN readers come to the same conclusion.

Re: LED Bulbs Save Substantial Energy

#48

Post by stan_rogers »

pmjordan wrote: post #46
eru wrote: post #45

Earlier quoted context omitted.

I don't know if all the cells in your eye are perfectly tuned to three peeks. I expect biological systems to show some variance.

The mechanism is chemical/physical, though, and depends on the absorption spectrum of a certain pigment molecule for each type of receptor. I strongly suspect the variance in those is likely to be tiny.

The fact that you can see a full spectrum -- as in a rainbow, thin-film refraction on a puddle on a paved street, etc. -- should be an indication that the band-pass for neural firing is relatively wide. If each optical receptor had a narrow acceptance window (the way that individual atoms absorb), there would be gaps in the rainbow. Remember that ALL of the colours you see in a rainbow are pure, composed entirely of photons of a particular wavelength proper to each of those colours. It's not RGB; it's not CMYK.

We can, to an extent, simulate a full spectrum through additive and subtractive colour mixing of "primaries", but it is only a simulation. (And Edwin Land demonstrated that we don't actually need all three of R, G and B in order to create the illusion of a full-colour picture with only a comparatively tiny gamut loss. It is a fragile thing, though, and requires the integrative function and cognitive mapping of our brains.

Similarly, we can easily tell the difference between full-spectrum lighting and discontinuous spectrum lighting. Discontinuous spectrum lighting makes us uncomfortable. None of the colours looks quite right. Food is unappetizing, pictures and people less attractive. Did the light-makers just miss the right mix of frequencies by a hair? No -- any scheme that relies on a small number of discreet wwavelengths will cause a similar discomfort. We may not know why we feels the way we feel at the time, but we sho' 'nuff knows we'se feelin' it.

Re: LED Bulbs Save Substantial Energy

#49

Post by pmjordan »

stan_rogers wrote: post #48
pmjordan wrote: post #46

Earlier quoted context omitted.

The mechanism is chemical/physical, though, and depends on the absorption spectrum of a certain pigment molecule for each type of receptor. I strongly suspect the variance in those is likely to be tiny.

The fact that you can see a full spectrum -- as in a rainbow, thin-film refraction on a puddle on a paved street, etc. -- should be an indication that the band-pass for neural firing is relatively wide. If each optical receptor had a narrow acceptance window (the way that individual atoms absorb), there would be gaps in the rainbow. Remember that ALL of the colours you see in a rainbow are pure, composed entirely of…

You make a good point - I forgot about indirect light and banded spectra interacting with surfaces.
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