As night falls on the MIT campus, lights are turned off, computers are shut down and copy machines are retired for the evening. But until recently, soda machines all over campus continued to operate at full power all night long, wasting energy and money. With the advent of a new energy-saving program, however, those days could soon be over.
The Department of Facilities has installed 30 "VendingMisers" on cold beverage machines across campus. Using a custom passive infrared sensor, these systems power down vending machines when the area around the machine is unoccupied and automatically repower the machines when traffic returns. The result is a potential 46 percent reduction in energy consumption on each machine. Over the course of a year, this translates to a savings of approximately $140 per machine. If the VendingMisers were installed on all 120 soda machines on campus, the savings for MIT could be as much as $17,000 per year.
"Some soda machines are not in appropriate locations to apply the VendingMiser, but most are," said Peter Cooper, director of utilities in Facilities. "With a one- to two-year payback on energy savings and the associated reduction in emissions, the decision to implement was easy."
One advantage of the VendingMiser is that the customer will never see a powered-down machine. In the event that someone approaches a machine at 4 a.m. wanting a soda, the VendingMiser will turn on the machine and deliver a cold beverage as usual. Cans are dispensed from the bottom of the machine, where they are coldest. By measuring ambient temperature and compressor current, the VendingMiser repowers the machine as needed to make sure the products are at a cold enough temperature at all times.
"Of the many energy and water conservation measures we have implemented or considered, VendingMiser is one of the most clever," Cooper said.
The VendingMiser program is the latest in a series of environmentally conscious initiatives undertaken by the Department of Facilities. Other recent efforts include recycling demolition debris at the Media Lab expansion site, replacing steam traps on radiators in central campus buildings, and installing signs encouraging people to use revolving doors throughout campus, in addition to the department's growing recycling program.
A version of this article appeared in MIT Tech Talk on June 5, 2002.