On behalf of the U.S. Department of Energy Solid-State Lighting (SSL) Program, Pacific Northwest National Laboratory (PNNL) is planning to conduct a study examining dirt depreciation and other optical changes occurring in LED street or area lights over long-term periods of performance, potentially approaching their full life cycles.
Stable long-term performance is a key selling point for LED luminaires, and for streetlights in particular. However, documented field experiences over a full life cycle are scant, because even the first generation of installed units are just now approaching their initially projected end of life (at 4,100 hours of annual operation, a 50,000-hour expected lifetime extends just over 12 years).
For the study, PNNL seeks LED street or area lights that, ideally, are nearing the end of their anticipated life; however, any luminaire with more than 10,000 cumulative hours of operation will be considered. There is no restriction on the type of luminaire, although a key requirement is the availability of a performance baseline. This can be through a pre-installation photometric test or via an equivalent unused luminaire (“shelf stock”) that can be submitted for comparison purposes. Compensation for submitted luminaires is available through replacement with similar make and model luminaires.
The following must be known about the luminaires submitted: total hours of use (within ±500 hours), installation location, and number of cleanings (if any) the luminaire has had. It is preferred, although not required, that the used luminaire still be functional. Only one used and one unused luminaire are needed, although multiple used and unused luminaires may be submitted.
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