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Lumens per watt



OK, so it's not PAR.  If you have PAR figures, please add them.  Use a
fixed pitch font for best results in viewing.


Incandescent
Vlt Watt Lumens/watt (initial)
120 100   17
Quartz-halogen
 12   5   10
     10   11
     20   15  (35 w/reflector)
     35        40
120  20   14
     35   17
     50   16
    100   20
Fluorescent  T-12
120       80
Fluorescent  T-8
120       90
Fluorescent  T-5
120       75  (70 for multiple u-tubes)
Metal halide
120 any   85


Around here, power costs about $.40 per watt-year (based on 3000 hours on
time).

DIY fluorescent costs about $1/watt for nice looking, $.16/watt for a shop
light hanging from the ceiling on chains.  Low-voltage halogens cost about
$.53/watt according to Tom Barr.

So per 1000 lumens (and remember, we should be talking about per PAR):
              Buy  Run($/year)
Incandescent  32   24      (either regular or quartz-halogen)
Fluorescent     11     5      (includes metal halides too, close enough)

I find it very hard to understand how anyone can argue for incandescent as
less costly.

Did I screw up one or more of the computations?

--
Dave Gomberg, San Francisco            mailto:gomberg at wcf_com
http://www.wcf.com/wcf
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