Oct. 1, 2009

Live Green: Let there be (less) light

by Paula Van Brocklin

The days of pop machines as beacons of light in long, dark hallways are gone, at least here at Iowa State.

Within the next few weeks, 168 of the 192 pop machines on campus will be equipped with a Vending Miser -- a device that automatically shuts off the machines' bright lights after a period of inactivity. The move should save about $80 per machine per year, for a total energy savings of $13,400 annually. For now, machines with card readers will not receive a Vending Miser, since its technology could deactivate the cards. Snack machines also are not included.

How it works

The Vending Miser, which looks a bit like a parking meter, contains a motion sensor. It sits on top of the pop machine and monitors movement. If there is no nearby activity for 15 minutes, the Vending Miser cuts the lights. When it detects movement about 15 to 20 feet away, the machine lights up again.

The Vending Miser is not tied to the machine's compressor, so when the lights shut off the cooling mechanism continues to run. In other words, your beverage of choice always will be cold.


The ISU Council on Sustainability piloted the Vending Miser last spring on two machines, one each in Carver Hall and Student Services Building. After conducting a one-week test, the group determined the cost savings would quickly pay for the initial cost of the equipment.

The project's start-up cost is about $18,400. Dr Pepper Snapple Group has agreed to pay half the cost to retrofit 68 machines, or $4,080. ISU Dining is contributing another $4,000, and vending services is picking up the rest of the tab. With these contributions plus the energy savings, the project should pay for itself in about 16 months.

Janet Krengel, chair of the council on sustainability, credits facilities planning and management, ISU Dining and the support of vice president for business and finance Warren Madden for making the Vending Miser project a reality.

"This has been just so amazing," Krengel said. "Everyone involved has been so terrific."