Winter break, partial shutdown yield overall energy savings

Fluctuating temperatures and fewer closed buildings during Iowa State's most recent winter break and partial university shutdown (mid December 2015 through early January 2016) proved to be a mixed bag for utilities consumption.

Compared to normal use, Iowa State's electrical usage during winter break (about 23 days) decreased 11 percent per day. During the partial university shutdown (approximately 14 days), electrical usage went down an additional 5 percent each day compared to normal use. The university's steam use decreased 9 percent per day over winter break. However, steam consumption inched up during the partial university shutdown, resulting in a 5 percent increase per day over normal use.

"The higher consumption is due to a number of reasons, including weather conditions and which buildings were occupied," said Jeff Witt, director of utilities services. 

Another reason for less savings is that fewer buildings are turning down thermostats during winter break, said Wendy Kisch, assistant director of facilities services. During the most recent break, for example, 15 buildings requested temperature setbacks. In 2014, that number was 19 and in 2013 it was 21. Kisch explained that some campus buildings don't have the ability to control temperatures room-by-room. In other words, it's heat and power for the whole building or nothing at all.

"If one occupant is working through the break and the rest of the building is empty and closed, the building system may have to operate to maintain a comfortable environment for the one occupant," she said.

The reduced energy consumption translated into cost savings as well. Utility savings for the entire winter break was $175,200 compared to normal consumption, with an additional savings of $24,750 during the partial shutdown. 

Electrical load


# of days

Average daily consumption (kWh*)

Daily energy savings (kWh)

Total energy savings (kWh)

Percent savings

School in session







Winter break







Additional savings during partial shutdown






 *kilowatt-hour, a billing unit for energy, equivalent to 1,000 watts of power sustained for one hour


Steam load


# of days

Average (lbs per HDD*)

Daily energy savings (lbs per HDD)

Total energy savings
(lbs per HDD)

Percent savings

School in session






Winter break






Additional savings during partial shutdown






*Heating Degree Day = a measurement that reflects the demand for energy needed to heat a building