With the ultimate goal of reducing energy costs, improving efficiency and creating greater continuity of services among the UNC healthcare facilities, UNC Hospitals’ decision-makers sought to address their chilled water infrastructure. The purpose of the project was to connect the facility’s two central chilled-water plants (14,000 tons total), thereby improving flexibility and redundancy.
McKim & Creed began by surveying existing chilled water plants, secondary and tertiary pumps, and distribution systems in eight hospital buildings. This allowed the team to see what worked best for this important utility. Hydraulic modeling was used to simulate water flows and pressure throughout the system after the plants were connected.
Two chilled water plants were converted to variable primary/variable secondary distribution systems. In addition to chiller plant upgrades, numerous air handling unit (AHU) upgrades were completed, including cooling coil replacements and pressure independent control valves. Upgrading the secondary chilled water pump speed/staging controls in the chiller plant provided a new 30-inch north secondary chilled water loop onsite and upgraded tertiary chilled water bridge piping/controls in eight buildings. This project included enabling and incorporating existing water-side economizer into the project.
McKim & Creed also provided a chiller plant optimization software package to provide additional energy savings.