An intelligent and energy-efficient light emitting diode (LED) street lighting system demonstrated by ESTCP at the Naval Surface Warfare Center (NSWC) – Carderock Division in Maryland, reduces electricity consumption by 75 percent, while improving light quality. Easily deployed in existing street lighting systems, this technology can save significant costs and energy across the Department of Defense (DoD).

Researchers at Virginia Tech, working in collaboration with Old Dominion University and Echelon Corporation, developed the smart multi-level demand-sensitive LED street lighting network that allows both clock-time and traffic-flow based lighting intensity control. The building blocks of the system include LED light fixtures, a streetlight controller, a traffic sensor, and a smart server.

The ESTCP demonstration monitored existing high pressure sodium (HPS) lamps for one year to develop a baseline of electricity consumption. After design and testing, the multi-level demand-sensitive LED street lighting system was installed at NSWC, replacing the existing HPS lamps with LEDs on the same lamp posts. Post-installation monitoring was performed for an additional year.

The LED system realized about 75 percent electricity savings with significantly better light quality and has the added advantage of eliminating mercury waste disposal. The power consumption of the HPS units was approximately 3.4 kW, which remained constant from dusk to dawn. The LED-based system power consumption was measured at 1.24 kW at its full intensity and reduced to about 0.71 kW at 50 percent intensity when there was no traffic. When traffic was detected, lights came back on to full intensity. Individuals on the base indicated a high level of user satisfaction with the LED street lighting system. The system has been 100 percent available and reliable without any failure since its installation more than 16 months ago.

LEDs cost about four times more than HPSs. The initial purchase costs are recovered in six years based on electricity savings and annual recurring operations and maintenance costs. The saving-to-investment ratio—the ratio of the total savings over the project's useful life to the cost of the project—is estimated at 1.92.

Replacing existing street lighting systems with intelligent LED systems can significantly reduce electricity consumption at DoD facilities across the nation. 

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