The increasing versatility of LEDs is plowing inroads to municipal infrastructures the world over.
LED stands for light-emitting diode — a semiconductor light process that’s radically different from traditional light processes including incandescence, florescence and sodium vapor.
LED lights consume a fraction of the energy of incandescents and are more efficient with what they do use. A whopping 90 to 95 percent of the energy consumed by incandescent bulbs converts to heat instead of light, compared to 65 to 70 percent in LEDs. And unlike fluorescent lights, LEDs’ output doesn’t vary according to whether they’re constructed in a bulb or tube shape.
Add an 18-20 year operating life and LED technology becomes instantly attractive for multiple industrial and public applications.
Early LED technology emitted exclusively a low-intensity, red light. But light output has risen significantly during the last two generations. The process now produces lamps that shine brighter while using far less electricity than most of their counterparts.
High wattage applications like roadway and street lighting, parking garages and lots, traffic signals and signage make the best use of LED technology, according to General Electric Outdoor Lighting Product Manager Tim Miller.
“We’re seeing a rapid adoption of LED systems for roadways,” Miller said. Cities in 29 states are either evaluating or have installed GE cobra head LED lighting as replacements for less energy-efficient light sources.
LED lights display unique benefits in cold environments, where they can increase a fixture’s efficiency by operating with occupancy sensors — something that fluorescent fixtures are ill suited to, Miller said. Additionally, tripled life expectancies among LED products contribute to offsetting their higher purchase price.
LED lighting was installed recently on a 74-mile long stretch of highway in Shenzen, China. If the lamps’ brightness and high coloring index made it an attractive product, it also heeded the Chinese government’s call for energy conservation, emission reduction, green economy and low carbon life.
Stamford, Conn., turned to LEDs in the face of a shrinking city budget and expanding responsibilities. Earlier this year, Stamford flipped the switch on $146,000 in annual savings resulting from replacing over 1,000 high-pressure, sodium streetlights with GE LED Roadway medium cobra head fixtures. New Brunswick, N.J., also adopted the technology for streetlamps installed during a three-year street revitalization project in 2010.
LED applications for emergency personnel are growing in popularity as well.
After emergency personnel complained about low light when they were standing out of the direction of the beam of older LED lights, engineers went to work on the problem. LED-based fixtures now distribute light more evenly than other lighting technologies.
In late 2009 the Michigan State Police department retrofitted red vehicle lamps with LEDs to reduce the hassle and expense of replacing sealed beam bulbs and servicing rotor motors. Patrol units also use red and blue LEDs facing to the rear of the vehicle and as well as headlight and tail light flashers.
On the other end of the scale, airport applications of LEDs are being scrutinized after a major installation at Hollis Municipal Airport in Oklahoma. The airport’s out-of-date, incandescent runway lights had been in poor shape. A state-of-the-art, FAA-approved LED system designed by Garver and installed a year ago included a new electrical vault, regulators and 45 fixtures on a lighting circuit. The system is expected to reduce airfield energy costs by 25 percent. According to the company the lights will also last more than 50 times longer than Hollis’ previous lighting technology. Pilots and ground report that the new LED lights—even on low intensity—are more visible than the old lights at high intensity.
LEDs’ caveat is that retrofit replacements need to be evaluated carefully.
Typically, one-for-one bulb replacements do not match performance and light quality expectations because the current reaching the bulb is too high. While LEDs consume less energy, their efficiency falls sharply when too much current is provided.
For best results, fixtures should be replaced so that the optics, thermal management and electrical design can be optimized for both light output and energy savings, Miller said. Electricians installing LED lights in interior settings should consider grouping the lights. In all settings, the directionality of the lamp dictates visibility.
The U.S. Department of Energy Municipal Solid State Lighting Consortium plans to launch a program of quality specification guidelines that can be used to make sure the basics of quality roadway lighting are offered through a common specification — a sort of template to help cities and utilities jump start solid-state lighting programs.
Currently, the consortium offers LED technology fact sheets, reports of commercial LED installations and specification guides on roadway luminaries, maintenance, efficiency performance and more at www1.eere.energy.gov/buildings/ssl.
Paving the way for some municipalities to switch to LED technology is the Energy Efficiency and Conservation Block Grant, an initiative funding energy efficiency and conservation programs across the country.
It might be worth a look, if a case study performed by the William J. Clinton Foundation this year is any indication. According to the study, a massive, five-year streetlight retrofit underway in Los Angeles in 2008 is already yielding 19 percent more energy savings than the 40 percent initially predicted.
Using the project as a template, the foundation is developing a “road map,” including funding options, aimed at municipalities that are considering going the LED route.
See the Clinton Foundation’s Los Angeles LED research and results at www.clintonfoundation.org/what-we-do/clinton-climate-initiative/cities/lighting.