The U.S. Department of Energy (DOE) has published the final report from a demonstration of LED roadway lighting conducted at three sites in Philadelphia, PA. The report provides a performance evaluation of 10 different LED luminaires—and compares them to the incumbent high-pressure sodium (HPS) luminaires—using manufacturer data, illuminance calculations, field measurements, and subjective observations. The evaluation was conducted by the DOE Municipal Solid-State Street Lighting Consortium and GATEWAY demonstration program, in collaboration with the City of Philadelphia.
Key findings include:
•All of the LED luminaires had higher application efficacies than their HPS counterparts; that is, they delivered more lumens to the target areas—roadway and sidewalk—per watt of input power. They also drew between 10% and 40% less power, and generally provided more uniform illumination.
•Field illuminance measurements had limited usefulness because of differences in pole spacing. Supplementary calculations using a representative model of each site indicated that the delivered illuminance of the LED products was generally similar to the baseline HPS luminaires.
•Although energy savings alone are unlikely to result in a reasonable payback period, additional savings from reduced maintenance could make widespread luminaire replacement cost-effective. As an example, LED luminaires installed on an elevated rail track at one of the three sites were less susceptible to premature failure from vibration than the HPS luminaires.
•Two sets of subjective evaluations were collected: one from local residents and another from lighting professionals. Both groups generally viewed the LED lighting favorably, especially compared to the typical HPS luminaires used in Philadelphia, and only minor differences were noted between the various LED products.
The report is available for download. This lighting demonstration is one of many DOE GATEWAY demonstrations that showcase high-performance LED products for general illumination.