Green Schools | News

U Michigan Tests Smart Lighting

• By Dian Schaffhauser
• 03/17/11

Limelight used to light up the stage in music halls. Now a wireless lighting system by the same name will get a test in a parking lot at the University of Michigan to see how well it can reduce energy usage and light up the space. The LimeLight system, developed by Michigan company twistHDM, makes use of a computer management system that allows individual lights to be turned off and on by program settings, motion sensors, and photocells.

In a $550,000 pilot project, the campus Parking & Transportation Services (PTS) department will be trying out the system to evaluate energy savings in a parking lot selected because the previous lighting system was obsolete. The old lighting fixtures used 250 watts compared with the new technology, which uses a 102-watt fluorescent fixture.

"We are thrilled to introduce this new breed of lighting system to the campus community," said PTS Executive Director Steve Dolan. "The LimeLight system automatically reacts to the lighting needs in any given location to enhance both the safety and energy efficiency of our structures."

• The 231 lighting fixtures in the 473-space parking structure can be controlled in multiple ways:
• Through computer programming. Each lighting fixture is assigned to a lighting group, and the typical schedule for those lights is set based on the facility's typical use patterns.
• Through motion sensors. When motion is detected, the sensors override the programming and activate lights. For example, as employees walk in the dark toward their cars, lighting would move with them and then continue doing so as the vehicle leaves the parking structure. The lights could be set to turn off after a certain period of inactivity.

Through photocells that sense ambient lighting levels. As the light changes, alternate programs could turn off individual lamps, in a practice known as "light harvesting."

"The sensors will detect when natural light is available and activate other programming that selectively turns off lights," said Diane DeLaTorre, associate director for parking operations and maintenance at PTS. "When it becomes darker, normal programming resumes. This feature will save energy and the life expectancy of the lamps."

The system also provides reporting that includes activity tracking, lamp-out location reports, and peak and minimum energy consumption statistics.

Dolan predicted that energy savings related to the lighting system could add up to 40 percent. "Our Parking and Transportation team is very focused on finding ways to reduce operating costs in all aspects of our operation," he noted. The LimeLight system, he added, "is a great example of how using technology can help PTS with its fiduciary and sustainable responsibilities."

The energy-savings technology cost about $100,000, which the university indicated will pay for itself in two to three years. U Michigan will review the success of the pilot in coming months to determine whether to convert other structures to LimeLight.

According to twistHDM, other institutions that have gone through LimeLight installations include the University of Georgia and Pomona College in California.