faces of the future - Illuminating Engineering Society

energy
BY WILLARD L. WARREN A D V I S O R
November’s column
described the disconnect
between
manufacturers, who
produce high CRI (Color Rendering
Index) LEDs, and lighting designers,
who complain about the color
rendering and color consistency
of white LEDs. In edisonreport.net,
Marcel van der Steen with Olino.org
explains that CRI was adopted by the
CIE, a 39-country lighting organization,
to establish a 0 to 100 grading
system for color valuing. Eight matte
swatches of various colors are illuminated
by a 5,000K full-spectrum
source and then scored, compared
to a test source. The scores are averaged
and Van der Steen points out
eight colors aren’t enough for a true
comparison. By averaging, one color
might match perfectly while another
misses, so while the average may be
high, some colors may be way off.
His solution is for the CIE to develop
a new CRI test that overcomes this
deficiency. It’s like the great Groucho
Marx’s “con” line: “Who do you
believe, me or your eyes”
My August LD+A “Letter to
the Editor” referred to the U.S.
Department of Energy (DOE)
Gateway study of roadway lighting,
comparing LED luminaires to HPS
cobra heads, as being misleading.
In September, the National
Lighting Products Information
Program (NLPIP), administered by
the Lighting Research Center (LRC)
at Rensselaer Polytechnic Institute
published “Specifier Reports:
Streetlights for Collector Roads,”
which stated: “Recently there have
been many LED street lighting demonstrations
(for example see the
U.S. DOE Gateway program). Some
of these demonstrations present
incomplete and potentially misleading
comparisons with incumbent
technologies. A complete comparison
should demonstrate the system’s
performance compared to
alternative technologies that meet
all of the required performance criteria.
Evaluations should be measured
or simulated excluding ambient light
and should include . . . full system
costs.”
On October 6, The Pacific
Northwest National Laboratory
(PNNL), which administers the
Gateway project for its major client,
the U.S. DOE, responded to the LRC
report: “Regardless of whether or not
[the accusations of inaccuracy] was
the intent of the text, we request that
the LRC consider revising the text to
either remove the apparent accusation,
or to clarify the real issues. If
the LRC takes issue with particular
aspects of particular Gateway reports,
we would welcome your professional
input in the form of direct correspondence.
Please note that while the
Energy Policy Act of 2005 mandates
the DOE to accelerate SSL (solidstate
lighting) technology, we do
advise end users to consider another
technology when it is immediately
clear that LED is not a good fit for
a given application. (You don’t see
Gateway reports for these projects
because once a decision is made to
use another technology in lieu of SSL,
our team is removed from the project.)
We request in the interest of continued
good relations between your
program and ours, the LRC will consider
revising this text appropriately.
‘Many LED street lighting demonstrations
present incomplete and potentially
misleading comparisons with incumbent
technologies’ NLPIP report
Please . . . let us know if and when you
will be making any changes.”
THE LRC RESPONSE
On October 13, the LRC responded
to the PNNL as follows: “The NLPIP
believes that the Gateway program
has not provided neutral comparisons
between streetlights with LEDs
and other light sources. Examples
might not have been selected randomly
and may not be compared to
other technologies that could deliver
better performance or cost.”
These were the specific objections
enumerated by NLPIP:
• In some installations, the average
illumination provided by the
new LED system was about half
that provided by the HPS system
it replaced. If a lower illuminance
level is acceptable in a particular
area, then this could also be
18 www.ies.org