Saturday, March 24, 2012
No LED replacement found for ornamental post-top street lights in DOE pilot project
An evaluation has determined that none of four different LED replacement products for ornamental post-top street lights could match the performance of the existing 100W HPS fixture.
The US Department of Energy (DOE) has published the final report from a demonstration of LED technology in ornamental post-top street lights, which was conducted in Sacramento, CA. Four different LED replacement products were evaluated using computer simulations, field measurements and laboratory testing. The evaluation was conducted by DOE's Municipal Solid-State Street Lighting Consortium in collaboration with the Sacramento Municipal Utility District and the City of Sacramento, with additional support from City consultant Mary Matteson Bryan.
In this pilot project, the study was restricted to lamp-ballast retrofit kits and complete luminaire replacements that would preserve the daytime appearance of the existing acorn-style luminaires. This challenge proved formidable, as the results indicate that none of the LED products evaluated could match the performance of the existing 100W high-pressure sodium (HPS) luminaires. The report, available for download, highlights some of the nuances involved in LED product selection.
To allow for apples-to-apples economic comparison, the pricing and input power of the LED products had to be scaled proportionately to represent hypothetical products which could match light levels from the HPS fixtures. Energy used by three of the scaled-up LED systems ranged from 63-90% of the baseline HPS. The fourth product would actually require an increase in energy use by 15%. None of the products would represent cost-effective alternatives to HPS.
In response to recent industry developments, the study also investigated the relative significance of mesopic multipliers offered in the new IES Lighting Handbook and the lumen maintenance extrapolation methodology offered in the new IES TM-21.
This pilot project is the first in a series conducted by the DOE Municipal Solid-State Street Lighting Consortium, which serves as an objective resource for LED product evaluation and a repository for valuable field experience and data. The data generated from this project may be useful to standards groups, manufacturers, and those considering retrofits to LED.