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26-29 Sept 2010 | Huntington Beach, CA

LD+A The Magazine of the Illuminating Engineering Society of North America

Sustainable Design

Big Technology on campus

Outdoor LE D luminaires keep popping up at the University of Colorado
BY PAUL TARRICONE

It’s 50 down and a few hundred to go at the University of Colorado, Boulder, where LED luminaires are replacing metal halide area lights along campus walkways and in parking areas.
According to campus electrical engineer Joe Branchaw, the project, which began in 2007, will be completed in phases, as funding becomes available. The switch to LED area and parking luminaires is aimed at helping the university reduce energy consumption by 20 percent from 2005-2006 levels by the end of the 2012 fiscal year as required by an Executive Order from the governor. The first 50 have been installed in six locations (five walkways and a parking deck) replacing metal-halide dome-top fixtures. Most of the new fixtures are mounted on existing poles to save money, but in some cases poles have also been replaced. Thus far, the university is using one luminaire type for the conversion (BetaLED’s The Edge).

The program began with a demonstration of two sample luminaires at separate test sites on campus. “We spent six to eight months looking at them,” Branchaw says. The three-bar 79-W LED fixtures were placed among the 175-W metal halide luminaires and evaluated based on at least three criteria. “The lumen output had to be the same as metal halide.” The footcandle levels measured up, says Branchaw, providing 10-15 fc directly below and 5 fc at a distance. “We also wanted to test them in cold and hot temperatures to see the performance in all environments.”
The third benchmark was more unorthodox: how would the fixture heads stand up to the birds that might nest on them? The new units have a flat top, a more inviting target for birds than the domed metal halides. With the heat sink directly below, Branchaw had concerns about the LEDs’ performance. Moreover, there was the matter of the mess left by birds sitting atop a flat surface which would be less of an issue on a dome.
Finally, Branchaw was drawn to the maintenance advantage. “It’s plug-and-play when replacing the LED bars when they fail.”

A WIDE SWATH
The luminaires are used in diverse locales across the 132-year-old campus. Some are on walkways leading to university housing, including a tunnel underpass that had previously been perceived as underlighted by students (including Branchaw’s daughter, a graduate of the university). The student courtyard was also converted, as was the Regent Administrative Center, where an LED security luminaire replaced an unsightly cobra head at the rear entrance.
In addition to their use on walkways, the luminaires have been installed on the top level of a two-level parking structure located next to the headquarters of the university’s police department. This application took some persuasion from Branchaw. “There was some reluctance and skepticism. There was a feeling that it would take more LED fixtures than fluorescent fixtures [to provide enough light]. Someone at the university had heard horror stories about how LEDs in a parking garage had to be removed because they didn’t put out the lumens needed.” Branchaw’s solution was to show, rather than tell. He took the university’s head of parking and transportation on a field trip to an offsite parking garage equipped with LED luminaires. Branchaw brought along a light meter to validate the light levels and eventually won approval for the installation.
The new luminaires also support the university’s pursuit of LEED certification for its facilities. Campus design standards mandate that all new buildings and major renovations meet LEED Gold standards. New full-cutoff LED lighting in front of the Visual Arts Complex is expected to earn a LEED credit for light-pollution reduction.
More credits—in the form of LEED points, completed projects and satisfied students—are likely to be earned at the University of Colorado, Boulder, over the next few years.

June 2010