On 12 September 2014 21:34, James Cameron <quozl@laptop.org> wrote:

>
*I wonder why an Efficacy of 123 lm/W was chosen?  It seems to have*
* been a goal far in advance of the state of the industry.*

Note that the 60 W prize was won in 2011 by Philips with a $10 million
payout.

For the PAR38 competition they note that *  " DOE cannot lower the efficacy
target because it was set by Congress."*

I know that does not answer your 'why' but it explains it remaining in the
face of reality.

I think it's a reasonable goal. People are pushing to attain it and will do
so.
I could build something that met the l/W and output spec NOW if I did not
have to also provide 1000 commercial quality samples, stump up <=3D $20,000
for testing, meet a power factor of >=3D 0.7, a CRI or about 90+, an
extremely tightly consistent CCT across all products, a
lumen maintenance spec higher than Philips meet on some markt products now,
and a bit more. I could even meet all the technical specs for a sample of 1
(or 10) if cost was not an issue. Or fitting it in a PAR38 profile :-).

ie this is a much harder spec than it may appear at first glance
Even then, the US energy use from PAR38 (90W) bulbs is only 1/3 of that
from 60W bulbs.

Top flux bin off the shelf LEDS from Cree attain about 200 l/W under some
operating conditions.
Lab reports are of around 300 l/W.

Good optics tends to take ~=3D  10% off the light
Losses of well under  1% are possible but costs probably too high (front
surface reflectors (std enough) with special coatings, ...)

Say use 200 l/W LEDs
10% for optical losses =3D 180 l/W.
Mains to LED conversion of say 80% gives 144 l/W
(Better possible)
Low CCT tends to result in lower l/W (colour away from eye optimum response
is one factor.)
High CRI typically needs multiple phosphors (Philips use LED-external
multiple phosphors).
Some loss there I imagine due to practicalities of either dotting/striping
or blocking losses if you mix them.
Say 10% (a wild guess) so about 130 l/W
Which looks to be about the L prize target.

ie / so - when the 300 l/W lab spawned 220-240-260 l/w products creep into
the top COTS bins and the acceptable price middle flux LEDs (main
production volume) creep over about 200 l/W at near full power then the
targets are liable to be meetable. I'd say 1 year with great skill, luck,
and magic. 2 to 3 years with skill, luck, and magic.

Russell
___________

L Prize overview.

        http://www.lightingprize.org/overview.stm

Really good/useful/interesting (choose 0 or more) CALIPER reports on
current PAR38 LED market products


http://www1.eere.energy.gov/buildings/ssl/application-par38.html

 Energy saving and environmental impact comment (nothing on byproducts)

       http://www.lightingprize.org/about_ssl.stm


Thanks.
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