> Actually, the lumens per watt is going up. Lumileds says that for a
> given power, you're getting about twice the light ever 18-24 months.
> Sort of the LED Moore's law. Check out the Lumileds website, I'm sure
> they'll have the info you seek.

I'd love that to be true. But I suspect that it's not so. Last time I
checked a top class LED is more efficient than many incandescent bulbs but
not as good as the top tungsten halogens. That was probably 6 months ago. If
the efficiency were exponentiatiing we would be abreast the best practice
THs now and expect double that by end 2005. I think efficiency is around 6%.

Googles ...

1986 - Tungsten halogen 40 watt = 20 lumens/watt = 800 lumens
Even at that level a 100 lumen LED (as per original reference) = 5 watts of
Tungsten halogen power.

Same year - low pressure sodium = 200 lumens per watt or 0.5 watt per 100
lumens.
Better than best LEDs now or as proposed in that article.

Edison's first bub was 1.4 lumens/watt

_______________

Target - > 50 l/w by 2006 for most non-domestic building lights
 Triphosphor -> Halo phosphate


http://www.mtprog.com/approvedbriefingnotes/ModellingEnergySavingsfromMinimumStandardsforCommerciallampefficiency.aspx?kintUniqueID=87

______________

      Type lm/W %
      light-emitting diode 0.04-20 [6] 0.005%-2.9%
      40W tungsten incandescent 12.6 [7] 1.9%
      60W tungsten incandescent 14.5 [7] 2.1%
      100W tungsten incandescent 17.5 [7] 2.6%
      glass halogen 16 2.3%
      quartz halogen 24 3.5%
      tungsten-halogen 18-25 [6] 2.6%-3.6%
      13W twin-tube fluorescent 56.3 [1] 8.2%
      compact fluorescent 45-60 [4] 15%-32% [3]
      xenon arc lamp 30-150 [5] 4.4%-22%
      mercury-xenon arc lamp 50-55 [5] 7.3%-8%
      high-temperature incandescent 35 [2] 5.14%
      ideal blackbody radiator 95 [2] 14% [7]
      ideal white light source 242.5 [2] 36%
      monochromatic 556nm source 680 [7] 100%



http://www.campusprogram.com/reference/en/wikipedia/l/li/light_bulb.html

_______________________________

Sulphur lamps.
150 lumens /watt
Not yer average bulb.

    http://www.thekrib.com/Lights/sulphur.html

Better technical comment.
Good pictures.
135,000 lumen from a golfball sized bulb - (and 1400 watts of RF to drive
it)
(= 96 l/W)

    http://www.sulfurlamp.com/tech.htm


Note - for the period that you heat your home there is no point in having
energy saving light sources unless capital cost is lower than alternatives.

        RM

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