WHAT IS LER?
Manufacturers, distributors, specifiers, and lighting designers have
a new tool to compare the energy-efficiency of fluorescent
luminaires. The Luminaire Efficacy Rating, or LER, is part of a
voluntary program being implemented by the lighting industry. Watch
for LER information on product literature.
The Energy Policy Act of 1992 (EPAct) called for a voluntary national
testing and information program for "widely used luminaires with the
potential for significant energy savings." Responsibility for
creation of the program was given to the lighting community: National
Electrical Manufacturers Association (NEMA), Amefican Lighting
Association (ALA), and other interested organizations. The U.S.
Department of Energy's (DoE) role was to provide financial and
technical assistance, and to evaluate whether the program met EPAct's
objectives. If it did not, EPAct prescribed government regulatory
action.
Consensus-building has been a key element in the stakeholders'
working group, the National Lighting Collaborative (NLC). The
Collaborative, established April 14, 1992, represents a broad
spectrum of opinion on lighting issues drawn from industry,
government, designer, and energy conservation member organizations.
In the words of Ms. Christine Ervin, DoE's Assistant Secretary for
Energy Efficiency and Renewable Energy, "Voluntary partnerships such
as those forged by the Collaborative play an important role in
helping America to become more energy efficient, to achieve our
environmental goals, and to stimulate sound economic growth."
The resulting program is based on NEMA Standards Publication No. LE5,
"Procedure for Determining Luminaire Efficacy Ratings for Fluorescent
Luminaires." The program received provisional approval from DoE on
March 15, 1996. The program is expected to gain momentum as more
manufacturers test and rate their luminaires and publicize the
results, and as designers and specifiers use the LER information in
their purchase decisions.
Currently, the program covers ten categories of fluorescent
luminaires used in the commercial and industrial sectors. Other
luminaire types will be added to the information program as
additional NEMA standards are developed and reviewed by the
Collaborative.
HOW IS "LER" CALCULATED?
LER is a single figure that expresses luminaire efficacy, the
luminaire's light output divided by the input power. The formula
is:
LER = [ luminaire efficiency (EFF) x total rated lamp lumens
(TLL) x ballast factor (BF)] divided by [luminaire watts
input]
Note that the effects of all components of the luminaire system are
included in the LER. Simply stated, this is similar to the 'miles per
gallon' rating for automobiles. "LER gets to the core of what energy
efficiency is all about -- to get more energy service using less
energy," says Francis Rubenstein, Staff Scientist, Lawrence Berkeley
Laboratory.
The LE5 document specifies the major fluorescent luminaire categories
covered and the standard industry test procedures. It is recommended
that luminaire testing and rating be performed with F40TI2/ES lamps
and energy- efficient magnetic ballasts, and F32T8 lamps with
electronic ballasts as well.
In addition to LER, LE5 also contains a calculation for the relative
energy costs of each rated luminaire. This estimates "cost of light,"
the yearly lighting energy cost per 1000 lumens of light output using
identical assumptions for operating hours and electricity price.
Because application and operating conditions vary widely, this number
is intended for comparison purposes rather than prediction of actual
energy usage.
WHAT DOES "LER" MEAN TO MANUFACTURERS?
Manufacturers have stated that using the new system will add
competitive advantage to their products and expect the testing and
rating procedures to spread rapidly through the industry. LER and
cost ratings are being added to product literature and used as
marketing tools. The LE5 document contains a sample format for
reporting LER to promote consistency throughout the industry.
Manufacturers are encouraged to communicate their progress in testing
and rating luminaires to NEMA. The U.S. Bureau of Census MA36L
Current Industrial Report has been modified beginning in 1995 to
collect luminaire shipment information as a partial means to evaluate
the impact and use of the LER. Continued participation is encouraged
to maintain the voluntary nature of the program.
WHAT DOES "LER" MEAN TO SPECIFIERS?
The LER and the "cost of light" provide guidance on comparative
energy-efficiency and costs of fluorescent luminaire options. It can
be added to specifications to ensure efficiency levels and used to
educate clients. LER should be used along with other
application-specific criteria in selecting the proper luminaire.
HOW DO WE USE "LER"?
Comparing the LER of two luminaires is not quite as simple as
comparing two automobiles' miles per gallon ratings. LE5
distinguishes between the major categories of fluorescent luminaires.
Each rating contains a two letter code indicating source and product
category, such as FL. "F" stands for fluorescent and "L" represents
the lensed product category. Only luminaires within a product
category should be compared. By the nature of their different
applications, a lensed fixture and a strip fixture (for example)
would fall into different LER ranges.
HOLD A PLACE OF METRICS OF QUALITY
The International Association of Lighting Designers (IALD) and the
Illuminating Engineering Society of North America (IESNA) are working
towards the development of numerical metrics for quality of lighting.
These metrics will someday be used as a tool to expand common
practice in lighting specification beyond the realm of the horizontal
foot-candle. In the future, the LER will be expanded to provide
information on quality in addition to efficiency. In the meantime,
LER should be used to complement application criteria in fluorescent
luminaire selection. Used with common sense and care, LER will be a
powerful tool for bringing energy-efficiency into the complex
equation of lighting purchase and specification decisions.
ADDITIONAL INFORMATION ON THE LER PROGRAM:
Kurt Riesenberg, Chair; National Lighting Collaborative, 1300 North
17th Street, Suite 1847, Rosslyn, VA 22209
Phone: 703-841-3226
At this time The National Lighting Collaborative is inactive
For additional information and related standards:
NEMA Luminaire Section