These photos show the contrast between HID (left) and LED lighting (right).
Increased demand for oil and gas in the face of dwindling reserves continues to make energy conservation an urgent priority. One way the Illinois Department of Transportation (IDOT) can make a difference in energy use is through new street lighting technology. While lighting provides essential safety for both drivers and pedestrians, the U.S. Department of Energy states that street lighting accounts for approximately 3% of total U.S. electricity consumption. To determine how street lighting could be more energy efficient in Illinois, IDOT and ICT partnered on project R27-076, which investigated the feasibility of using light emitting diode (LED) street lighting.
LEDs are a promising energy-efficient lighting source. Developed by Nick Holonyak, who retired in July 2013 from the University of Illinois at Urbana-Champaign, LEDs have been used since the 1960s as indicator lamps in consumer products, and recent rapid advancements in LED lighting technologies are making them a more feasible alternative for street lighting. It is expected that high-power LEDs will replace around 25% to 30% of incandescent lighting applications by 2025.
ICT researcher Rahim Benekohal, University of Illinois at Urbana-Champaign, conducted an in-depth comparison of LED and high-intensity discharge (HID) roadway luminaires. Additionally, Benekohal and his research team documented test procedures for photometric measurements of roadway lighting installations and IDOT’s roadway lighting requirements. Benekohal states: “LEDs reduce light pollution and glare, and LED luminaires with high blue content can be detected more easily by the human eye compared with high-pressure sodium lamps.”
This study allows IDOT to make informed decisions about roadway lighting and helps ensure adoption of the most economical and energy-efficient solutions. Mark Seppelt, Electrical Unit Chief for IDOT’s Bureau of Design and Environment, who facilitated the project as Technical Review Panel chair, states: “This research will allow IDOT to evaluate the possibility of replacing conventional HID lighting by comparing LED performance to that of existing light sources. The outcome of this study will offer valuable information in determining the conditions under which IDOT can reduce costs and/or improve roadway lighting by implementing new lighting technology.”
Phase 2 of this project (R27-123) is under way. Topics being addressed in that phase include light loss factors, evaluating the suitability of recent developments in LED technology, and life-cycle cost analyses.