Update! A new contract has been signed with our vending service provider and all vending machines (drink and snack) will be Energy Star! Basically, the technology of vending misers has been incorporated into the machines themselves, making the addition of Vending Misers unnecessary. Read more in this article from Climate Edu. – Aug 25, 2009.
How much energy does a vending machine use to light its signs and cool your sodas? A lot more than you might think at first glance. TCI investigated this source of campus emissions and discovered that a simple technology can make a big difference.
On the Tufts’ Medford and Grafton campus, about 75 vending machines were equipped with Vending Misers in 2001. These devices plug in to the machines to reduce energy use while still maintaining the necessary cooling temperature. An occupancy sensor turns off the lights when no one is near the vending machine and sensors reduces compressor use.
Using a line logger, we measured the electricity use of a soda machine in Bush Hall for one typical week before and after installation. The results are shown in the table below.
|Without Vending Miser||With Vending Miser|
Length of time monitored
|1 week||1 week|
|66.71 kWh||33 kWh|
Cost of device
Cost of electricity @ $0.11/kWh (for one week)
Cost over 52 weeks
|N/A||less than 1 year|
CO2 savings per machine
CO2 savings on 75 machines
The estimated savings from this one machine is approx. $192/year. Yet the savings are likely to be even higher because the annual calculation assumes that the dorm is occupied throughout the year. Vacation savings will be substantially higher.
To inform people about the energy saving technology, all soda machines with misers now display the following sign:
As of October 2001, about 75 Vending Misers have been installed on the Medford campus. About a dozen of them have been installed on the Grafton Campus.
In the process of installing the misers, several issues complicated the project:
Installation of the Vending Misers is not always easy. About 17 of the soda machines at Tufts must be moved away from the walls before the misers can be installed.
The machines are very heavy and must be moved by the vending machine company. After the misers are in place, the machines must be moved back.
Many of the soda machine plugs were inaccessible. The Coca Cola distributor had to spend a whole day on campus, emptying out machines, moving them and putting them back in place, after the misers had been installed.
Although staff from TCI put the misers in place, they then had to be permanently mounted on the walls by a contractor.
These installation factors (requiring several different workers and steps) add to the installation costs of the machines. The payback rate will therefore probably be closer to 2-3 years, rather than the 1 year we had at first calculated (see table above). Nevertheless, the Vending Misers are a worthwhile investment and will save the university a considerable amount of energy for a simple technology!
In some of the locations that have several vending machine on the same electrical circuit, the circuit tripped out, because all them machines come on at the same time, when someone walks past the machines and the motion sensors register.
Repeaters that stagger the turning on of the machines have been installed in some of the problematic areas but still the electrical load was too high. An electrician had to be hired to install a new additional circuit.
We regularly have to inventory the vending machines to make sure that all beverage machines are plugged into vending misers and that the vending misers work properly (e.g. don’t have obstructed motion sensors).
Please contact the manufacturer directly. While we do have a handout on lessons learned from 2001, please note that much may have changed in the intervening years so we are no longer able to answer individual questions about installing vending misers. Thank you.