University of Iowa
OP-T2-13: Timers for Temperature Control

The majority of the heating and cooling systems in campus buildings are monitored and controlled by Direct Digital Control “Building Automation Systems” (BAS). The various departments have been polled to determine when the buildings are typically considered to be “unoccupied.” The BAS is then programmed to shut key air handling systems down during the unoccupied periods. The control systems in some of the buildings have been configured to allow occupants that may choose to be in the building during unoccupied periods to turn on the air handling system that serves their particular work zone for a pre-determined period of time. Within the past five years, a number of campus buildings have been retrofitted with electronic occupancy sensors to not only shut lights off automatically but also automatically “reset” the temperature control setpoints in the unoccupied periods. When the BAS detects that the area is unoccupied, the air flow into the space is automatically reduced and the temperature setpoints are also reset (increased during the cooling season and decreased during the heating season) to reduce energy consumption during the times the spaces are unoccupied. The BAS has been programmed to make sure the spaces do not get too cool during the heating season or get too warm during the cooling season.