The University has one of the most sophisticated chilled water generating systems in the world. Chilled Water, which is used to cool buildings and equipment, is provided by either the District Cooling Systems comprised of a network of chiller plants and underground piping or by stand alone chillers dedicated to individual buildings.

The District Cooling System for the main campus consists of five chiller plants with a combined capacity of 50,000 tons. The plants are interconnected by underground piping and operated as one production system using a networked Supervisory Control and Data Acquisition (SCADA) system. From a single console, operators can manage and balance loads among the chiller plants, use capacity anywhere in the system and continue operating in critical areas despite cooling equipment failure or utility outages.

Two of the chiller plants house both steam absorption and electric centrifugal chillers; the other three house only electric centrifugal chillers, allowing us to quickly respond to outages of either energy source, as well as manage costs by monitoring the local electric utility’s hourly pricing program.

The Operations Center also includes a 5 million gallon stratified cold water storage tank. The thermal storage system shifts a portion of the University’s chilled water production to off peak periods, reducing the need for electric purchases from Duke Energy during peak times.

After it is chilled, the water flows into a loop piping system, which distributes the water to bridge interface systems that control the flow of chilled water in and out of each of the campus buildings. These bridge interface systems ensure that the buildings receive and efficiently use the chilled water to meet their cooling demand. The distribution system can pump up to 100,000 gallons of chilled water per minute through more than 22 miles of underground piping and 150 individual building bridge systems. When the water has been used (warmed), it is returned to a chiller plant to be chilled again.

In addition, Chilled Water Systems manages eight stand-alone chillers. Generally, these chillers serve individual building(s) that cannot be serviced by the University’s distribution system.

System Design and Capacity

The University owns, maintains and operates a district cooling system comprised of 5 production plants, a thermal energy storage system, a distribution system with over 22 miles of underground piping and building bridge systems consisting of over 150 bridges servicing over 140 locations. The Tomkins Operation Center included in the list below, can be run as a production plant or to recharge the Thermal Storage System. See How Things Work for an illustration of how the District Cooling System interrelates with our other campus energy systems.

Production Plant Date Built Electrical Centrifugal Chillers Steam Absorption Chillers Tons Capacity
North Chiller Plant 1970 8 3 12,750
Cobb Chiller Plant 2006 5 10,000
Tomkins Center 2006 3 6,000
South Chiller Plant 1976 10 2 19,000
East Chiller Plant 1983 3 2,635

The University also operates and maintains remote electrical centrifugal chiller systems which generally serve individual building(s) that cannot be serviced by the distribution system.

Remote System Tons Capacity
Brooks Hall 50
Aycock Family Medicine 187
Child Development Center 80
General Administration 265
440 West Franklin 253
Radio Station 80
Friday Center 875
Friday Center 394
Facility Services 394
Mobile 185

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