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Old 07-28-09, 03:07 PM   #7
Sandcruiser
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the reason I ask is that I'm under the impression that for most single lamps, lumens/watt falls off as you increase wattage.

ie: a 25 watt bulb is not 1/2 the brightness of a 50 watt bulb (in incandescent)

in comparison: if you go from 20 watts of LED lighting, up to 50 watts of LED lighting, you have increased the number of emitters, not just the wattage. The same holds (more or less) true for FL tubes-- a 4ft, 40w tube is putting out about the same Lumens/watt as a 2ft 20w tube (from my recollection) but my memory tells me that a 500w metal halide is not twice the brightness of a 250w metal halide, nor are 5 x 100w metal halides the same brightness as 1x500w metal halide.

Still, the comparison of different technologies is interesting, at least.

I'd like to see an additional column added for embodied energy and toxity. ie: it is pretty cheap and easy to build an incandscent bulb, with little toxicity. It is expensive (for now) to build an LED. We all know which lasts longer and which is more efficient, but if you are looking at using one vs the other for a light that is only one for a few hours/year (in theory)... at what point is there true break-even?

I suppose that the issue is even more complicated when you talk about heavy metals found in halides or florescent lights. The costs of disposal/recycling or pollution are much higher for those lights (around here, they are all going to end up in landfill or burn-pile. I no longer buy floro tubes because of this problem).
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