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M

m Ransley

Jan 1, 1970
0
Am I correct in that an incandesant light outputs 17 Lumen Per Watt
and only produces a small amount of light per watt. Ex a 100 watt bulb
produces 10 watts light , 90 watts heat, effectively making it a heater
that produces light.
A T-8 flouresent can produce near 110 LPW , 6.5 x an incandesant.
Making T- 8 the most efficient home lighting.
Is 170 LPW the limit of light output per watt.
Is T-8 the most efficient,
What can the near future offer us in LPW increases.
Are my figures correct
 
M

Mark or Sue

Jan 1, 1970
0
m Ransley said:
Am I correct in that an incandesant light outputs 17 Lumen Per Watt
and only produces a small amount of light per watt. Ex a 100 watt bulb
produces 10 watts light , 90 watts heat, effectively making it a heater
that produces light.
A T-8 flouresent can produce near 110 LPW , 6.5 x an incandesant.
Making T- 8 the most efficient home lighting.
Is 170 LPW the limit of light output per watt.
Is T-8 the most efficient,
What can the near future offer us in LPW increases.
Are my figures correct

Sort of. The light produced by an incandescent source is non linear. The larger the lamp (in watts),
the higher the lumens per watt. The little 25W and 40W lamps are pathetic for efficiency, whereas
the 200W and 300W lamps are much better. But they are still in the 5 to 15 lumens per watt range.
Halogen versions improve on this somewhat.

There are some new LED based lamps with edison bases that are another small step up in efficiency.
They also produce more usable lumens because of the nature of the light source. But I've never seen
them to know what their light quality is like. If its like the LED flashlights, they could be hard
on the eyes. The future may be here for a direct incandescent replacements.

Fluorescents are a huge jump in efficiency. Now that they have decent color temperatures and good
CRI's, they aren't a bad source of lighting at all (about 5X that of incandescents).

There are even more efficient light sources (metal halide I believe), but they all seem to have a
long warm up time so their uses are limited.

No matter which light source you choose, just about all the power will be dissipated as heat. In the
fluorescent, a twin 32w fixture will dissipate about 64 watts between the ballast and the lamps. No
way around this for just about anything electrical.
 
D

Dale Farmer

Jan 1, 1970
0
Stuart said:
Compact Fluorescent Lights seem to be doing a pretty good job of
eating into the incandescent market.. 18W for the same lighting value
of a 60 Incandescent. bulb. We have bought a few in the house to test
how long they last and to see if it is actually worth paying the $8
CDN for a bulb instead of 8 or 10 bulbs at $0.60 ea.

Stu Brown
Saskatoon SK

IN a lot of places, the local power company is subsidizing the cost
of
the bulbs in local stores. Here in Massachusetts, one of the local
discount
stores has bins full of CF bulbs for one dollar each. Limited
selection, but
can't beat the price.

--Dale
 
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