Chilled Water Distribution

Stanford’s chilled water system distributes cooling energy produced at the Central Energy Facility to the air conditioned buildings on campus. The distribution system consists of parallel supply and return piping, circulating the chilled water throughout campus.

Chilled water at 44°F is generated at the Central Energy Facility, using steam absorption chillers, steam turbine drive chillers and electric driven centrifugal and screw chillers. The chilled water is distributed radially from the CEF via underground distribution mains (18” to 30” diameter) to form CW service loops to the Campus and Medical Center.

The underground chilled water piping system is ductile iron piping with some small branch lines using PVC. Typical building laterals are 4”-6” and supply peak cooling loads from 50 tons for smaller buildings up to 800 tons for research centers and 2000-4000 tons for main hospitals.

Each service enter the building underground into the basement mechanical room where the flow is metered in gpm and the supply temperature (42-44°F) and return temperature (52-60°F) are measured, resulting in a energy use rate in cooling tons. In the building mechanical rooms, secondary pumps send the chilled water to equipment cooling, HVAC cooling coils, HVAC chilled beams, and other special cooling requirements.
All chilled water systems are closed loop, with water makeup for leakage and water treatment being done centrally at the CEF.