In September, the National Lighting Product Information Program (NLPIP) at Rensselaer Polytechnic Institute’s Lighting Research Center (LRC) released a publication called Specifier Reports: Streetlights for Collector Roads, which provides objective performance information on street lighting technologies including high pressure sodium (HPS), induction, light-emitting diode (LED), and pulse start metal halide (PSMH). The streetlights selected for evaluation were recommended in 2009 by nine different manufacturer representatives as equivalent to the incumbent 150W HPS streetlight.
The report concluded that the LED streetlights recommended by the manufacturer representatives as replacements for the incumbent streetlight would cost more than twice as much to own and operate over the life of the streetlights, primarily because the LED streetlights required narrower pole spacings to meet the recommended practice for illuminating collector roads, and the cost of the poles per mile dominated the life cycle costs.
NLPIP received some critical comments from government representatives who claimed that NLPIP made an error in the report by selecting “underpowered” luminaires to be equals to existing fixtures, even though “higher-powered” models might be available.
“The fact is that NLPIP’s methodology has been seriously misrepresented. The methodology emulated the luminaire selection process used by many lighting specifiers, which means that the luminaries analyzed by NLPIP were those actually recommended by manufacturer representatives as equivalent to an incumbent technology, a 150W HPS luminaire with a Type III distribution,” said LRC Director Mark Rea, Ph.D. “It is disappointing that all six of the LED manufacturer representatives recommended streetlights with lower light output than the incumbent technology, but, hopefully, the report underscores for specifiers the problems associated with blindly accepting all the current claims surrounding solid-state lighting. That should be the focus of discussion among those in the industry.”
Analysis with “high powered” LED streetlights
To minimize misinformation, NLPIP added an addendum to Specifier Reports: Streetlights for Collector Roads. The addendum is an analysis of “higher-powered” LED streetlights that NLPIP identified from the websites of the LED streetlight manufacturers included in the main report. NLPIP investigated LED streetlights with enough light output to meet lighting criteria as defined in the American National Standard Practice for Roadway Lighting, ANSI/IESNA RP-8-00 (R2005) at the same pole spacing as typical HPS streetlights. Because poles dominate the total life cycle costs of roadway lighting systems, the pole spacing was held constant for this analysis. Current (October–November 2010) LED streetlight prices and manufacturer-provided photometric data were used.
The results show that the average relative life cycle cost (excluding pole costs) for the LED streetlights would be 2.3 times the average relative life cycle cost of the 150W HPS streetlights if the LED modules were to require replacement after 25,000 hours of operation. An LED module life of 50,000 hours would result in the LED streetlights having an average relative life cycle cost 1.7 times that of the 150W HPS streetlights.
These results are based on a comparison between lighting technologies, using a technology-neutral methodology, according to NLPIP.
“We encourage specifiers to actually read Specifier Reports: Streetlights for Collector Roads and draw their own conclusions, rather than relying on faulty interpretations posted on blogs or distributed via mass emails,” said Rea. “There is no doubt that LED luminaires will play a strong role in the future of lighting. NLPIP is simply raising awareness of the strengths and weaknesses of current technologies and products in order to help specifiers make informed decisions. NLPIP has contributed to the industry in this way for 20 years by providing access to objective, verifiable, research-based data.”
NLPIP’s response to comments made about the report can be accessed at www.lrc.rpi.edu/programs/NLPIP/SR_StreetlightResponses.asp.
The entire report, including “Addendum: Analysis of the costs of LED streetlights that meet IES RP-8 roadway lighting criteria for collector roads at the same pole spacing as HPS streetlights,” is available at www.lrc.rpi.edu/nlpip/publicationDetails.asp?id=927&type=1.
About the National Lighting Product Information Program (NLPIP)
NLPIP, established by the Lighting Research Center (LRC) in 1990, helps lighting professionals, contractors, designers, building managers, homeowners, and other consumers find and effectively use efficient, quality products that meet their lighting needs. With the support of government agencies, public benefit organizations, and electric utilities, NLPIP disseminates objective, accurate, timely, manufacturer-specific information about energy-efficient lighting products in its series of Lighting Answers, Lighting Diagnostics, Specifier Reports, and Technical Guides. NLPIP sponsors include Centre for Energy Advancement through Technological Innovation (CEATI International Inc.), the New York State Energy Research and Development Authority (NYSERDA), and the United States Environmental Protection Agency (US EPA). Learn more at www.lrc.rpi.edu/programs/NLPIP/index.asp.