The U.S.Department of Energy(DOE)has published the evaluation report from a GATEWAY demonstration in New York City's Central Park,conducted in collaboration with The Climate Group and the New York City Department of Transportation.LED post-top luminaires from five different manufacturers were installed along paved walking trails and evaluated against the metal halide luminaires that were in the park at the time.The report includes product comparisons across performance criteria of energy savings,improved horizontal and vertical illuminance,life-cycle cost,and simple payback,as well as considerations regarding orientation,spacing,and color quality.
Key findings include:
•All of the LED products evaluated provided significant energy reductions relative to the metal halide baseline,ranging from 50%to 83%energy savings.
•Four of the LED products offered lower life-cycle costs than the incumbent luminaire based on an analysis period of 75,000 operating hours.
•For walkways in general,both horizontal and vertical illuminance values are important.The LED products provided a larger percentage of their output as downlight—because of the directional nature of LEDs and better optical control offered by the smaller emitters—and produced considerably less uplight than the baseline.This difference partially explains how some of the LED products produced higher measured illuminance values even with lower overall output.
•Proper orientation of directional luminaires can be a challenge.With an objective to focus illuminance on the pathway versus the surrounding grassy areas,this evaluation considered both symmetric and asymmetric distributions,but a strictly asymmetric approach would not necessarily work for all sites.
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.
