The Illuminating Engineering Society (IES) held the 2010 Street and Area Lighting Conference (SALC) in Huntington Beach, California in late September and LED-based solid state lighting (SSL) was the focus of the majority of the presentations. The scheduled also included comparisons of different lighting types and a couple of reality checks presented by lighting designers.
The first reality check came early in the program on Monday morning when Lighting Design Alliance President Chip Israel presented “No Mo’ Pole Ploppin’.” Israel challenged several concepts that the outdoor lighting industry has largely accepted as true such as SSL is always more efficient and light trespass is always bad.
Israel’s points were clear that lighting must match the application at hand. Sometimes light trespass on a sidewalk or washing a wall along a sidewalk creates a safer and more inviting environment without any negative impact. And he showed how even incandescent lights can be an energy-efficient and long-life choice in some outdoor applications when the designer chooses low-wattage lamps and adds dimming control to extend lamp life to the 50,000 hour range.
Israel has certainly done his share of LED projects as well and is a proponent of SSL used correctly. He even pointed out that we may be lighting the wrong things with street lights in some cases. To prompt thought, he asked whether lower-power near-ground lights such as those used along airport runways might be superior to lights mounted high on poles in some cases.
Most presenters, however focused on SSL and that seemed to be the topic that most in the crowd were interested in learning more about. The program and a number of presentations focused on LED street-light installations including some data on performance and cost.
SSL Street light trials
The cities of Huntington Beach, Los Angeles, and San Jose all presented papers on their SSL street-light projects. Moreover, the Electric Power Research Institute (EPRI) and The Climate Group’s LightSavers organization presented information on multiple trials in which they are involved.
Highlights of the trial data came from Los Angeles – the largest SSL street light installation in the world. Ed Ebrahimian, Director Bureau of Street Lighting in Los Angeles, reported that the city has installed 30,000 SSL street lights out of the 140,000 they plan to retrofit with LEDs. The city is spending just under $500 per light replaced with LEDs including the cost of material, labor, and engineering. Ultimately the city hopes to save $10 million annually in energy and maintenance savings.
The city of San Jose, CA has undertaken a much smaller trial but delivered some very interesting results. The city worked with the Virginia Tech Transportation Institute to measure both light levels and the ability of humans in a moving vehicle to detect objects under different types and levels of light. Consultant Nancy Clanton reported that the LED lights operating at lower power than legacy lights produced superior object recognition results, and Clanton attributed the LED advantage to the fact that LEDs produced white or broad-spectrum light.
Of course not everything was all about LEDs. Ronald Gelten of Philips Lighting presented “Blinded by the lights” that covered the basics of how LEDs and other types of lights operate and the relative advantages of each. Gelten has developed a series of pentagonal-shaped graphs that present the attributes of various lighting types on five axes. For example, he has a cost comparison that incorporates payback time, initial cost, energy savings, replacement cycles, and preventative maintenance.
Indeed Mohammed Rashed, Chief Engineer of Electricity from the city of Chicago, Illinois, presented a case study on why the city is installing ceramic metal halide (MH) street lights. The MH alternative fared better in Gelten’s cost analysis even though pilot tests in Chicago indicated a preference among residents for LEDs.
The week concluded with a move north into the city of Los Angeles where a number of people toured parts of the LED installation there accompanied by Ebrahimian. The tour provided a clear demonstration that SSL delivered a more even light distribution with no bright or dark spots relative to high-pressure sodium (HPS) lights.
In addition, the DOE Municipal Solid-State Street Lighting Consortium held its first workshop in Los Angeles on Thursday after SALC ended. Much of the material at the workshop mirrored presentations from SALC. But Mark McClear, Director of Business Development at Cree, made one surprising point. Cree has LEDs running in the lab that have maintained L70 performance for more than 100,000 hours. Tongue in cheek he suggested LEDs last forever in ideal conditions. But McClear also pointed out that Cree had replaced the drivers in the long running LED test -- making the point that reliable SSL is a system-design problem.
Make sure you peruse the November issue of LEDs Magazine. We’ll have a more detailed report on SALC in the issue.