What does it take to change from heating to cooling campus buildings?

It’s the time of year when campus buildings start to transition from a need for air conditioning to heat. What does it take to make the seasonal switch?

According to Facilities, Planning and Management, providing heat to campus buildings in most cases is simple and fast because the supply of steam to the building air-handling units is always on. But some older buildings have to be manually turned off during the cooling season (usually May 1-Oct. 15, although this can vary depending on weather trends and other factors). The buildings that have to be shut off during warmer months also need to be turned back on in the cooler months, and they usually use radiation heat.

Changing over to air conditioning during the warmer months is more complicated, though. Currently, 120 buildings are connected to the central chilled water system, and 14 buildings have local building chillers. To cool the buildings, the chilled water is circulated through the cooling coils of several hundred air-handling units in the various buildings, pushing cool, conditioned air to the occupied spaces.

Unlike the residential units, the majority of the cooling coils are drained as the cooling season ends and refilled with chilled water when the weather starts to warm up again, all to keep the coils from freezing during the winter. It usually takes three to four weeks to do this.

A priority system is used when switching from heating to cooling season. First priority is UW Hospital and Clinics essential operations, followed by buildings or rooms that have animals or that involve temperature-sensitive experiments and essential server rooms; buildings or rooms with sealed windows, high heat-generating equipment and high-occupancy fluctuations; and finally buildings or rooms with operable windows in most rooms for ventilation and that have no experimental activities that might be affected by higher temperatures.