Living in an area where it can snow in May and be 85 degrees in November, it is always a challenge to determine when to turn on the heat and turn off the air conditioning. As a general rule, the Plant department targets May 15 to switch from heat to air conditioning and October 15 to switch from air conditioning to heat. However, due to the unpredictability of the weather, the Physical Plant monitors conditions and will adjust those dates to suit the predicted conditions. During the switchover period, it is advisable to dress appropriately and carry a sweater in the event that we experience cool mornings and warmer afternoons.

In many buildings, air conditioning and heating systems require approximately three days to switch over and a few more days to stabilize. An outside air temperature above 75 degrees F. is needed to calibrate many of the air-cooled condensing systems, and those are usually the last ones to switch over.

Thermostats are calibrated on a routine basis by vendors and/or Plant mechanics. During the air conditioning season, thermostats are set at 72 degrees F. A fluctuation of 2 degrees F is to be expected. In the event of extremely hot weather, most systems will provide a 15-degree F. differential inside. During the heating season, thermostats are set at 70 degrees F. with an expected variation of 2 degrees F.