Inside Iowa State: Iowa State University

INSIDE IOWA STATE
April 5, 2002

Sensors turn off lights in vacant rooms

by Linda Charles
Automatic light switches are replacing standard light switches in restrooms across the university in the latest energy conservation move.

Selected classrooms and conference rooms also will have the switches, said Bob Currie, assistant director of facilities services. Facilities services staff hope to install all the sensors by the end of May, he said.

The automatic switches use passive infrared technology to sense motion. When people enter rooms, the lights are turned on automatically. The switches also turn the lights off when no one is in the room, Currie said.

The switches are capable of keeping the lights turned off if adequate daylight is present, even if people are in the room. However, the switches can be overridden if a hand is placed over the sensor for a short period. In that case, the lights will remain on until the space is unoccupied, Currie said.

How much energy will be saved is "somewhat speculative," Currie said. There are many factors for each room, including whether someone currently is turning off the lights and how often the room is accessed.

A typical restroom has four two-tube, 32-watt fluorescent fixtures, Currie said. If the lights could be turned off 75 percent of the time, the university would save about $85 per year at current electrical rates.

"The cost of a switch is about $37," Currie said, "and it takes less than 30 minutes to install, providing a payback of less than one year, based on the example."

Those who think they have a room that would benefit from an occupancy sensor should contact the FPM service center, 4-5100, or make the request online at: http://www.fpm.iastate.edu.