Lighting the Way to a More Energy Efficient Future
What is a large, essential, and often unnoticed electricity consumer on DoD facilities? Street and other outdoor lighting. Entire cities have even begun to address this concern with large scale “relighting” projects. Forbes magazine recently published an article about the City of Los Angeles relighting all their public outdoor spaces with LEDs. The city expects to save approximately $8.8 million on its electric bill this year and approximately $3 million in maintenance costs. Similarly, ESTCP along with Virginia Tech and Old Dominion University demonstrated a relighting project, Bi-Level Demand-Sensitive LED Street Lighting Systems that will improve light quality and save on electricity, while sustaining lighting functionality.
Outdoor lighting is important for the safety it provides for nighttime traffic operations associated with pedestrian pathways, roadways, parking lots, storage centers, housing, and perimeter areas. The use of LED lighting dramatically improves sensitivity and image quality captured by security cameras, which are more sensitive to the white light emitted from LEDs. Today almost all streetlights and parking lot lights being deployed at many DoD installations are not dimmable and use high intensity discharge (HID) lamps, with high‐pressure sodium (HPS) and metal halide (MH) being the most common choice. This results in poor light quality and more electricity usage than is necessary to keep foot and vehicle traffic safe. Completed in early 2014, the ESTCP relighting project was conducted at the Naval Surface Warfare Center (NSWC) Carderock Division in West Bethesda, MD to address this very issue.
The outdoor lighting technology used for this demonstration included a dimming feature that allowed for the full light intensity to be dimmed when not needed for foot or vehicle traffic and motion sensors that detect traffic or pedestrian movement. These features were interfaced to an intelligent control system that reduces false starts. The LED-based streetlights have been shown to reduce energy use by as much as 50% when compared with that of the traditional HPS lamps. Savings increase further when LEDs are compared with MH lamps. LEDs can also be dimmed without any impact on lifespan and color output.
The demonstration of the energy-efficient bi-level demand-sensitive street lighting system achieved energy savings and decreases in CO2 emissions of 74%. The payback period for the system is 6 years. The longer life of LEDs, the instant strike-to-respond to traffic or pedestrian movements, and the reduction in hazardous materials from not using MH lamps result in additional environmental benefits as well. Users at the DoD facility also reported a high-level of satisfaction with the new outdoor lighting.
With this new technology, energy managers at DoD facilities will be able to continue providing a safe environment to both personnel and visitors while reducing electricity consumption. The Final Report and full results of this demonstration can be found on the ESTCP website.