Duke University

Keeping the Blue Devils Cool!

Trane has helped Duke University modernize its campus-wide HVAC systems for better comfort, greater efficiency and reduced maintenance costs.

Challenge

In 1999 Duke University had no central chilled water plant. Each building had its own chiller plant or other type air conditioning system. As more buildings were added, the need for more operations and maintenance staff grew.

Solution

To ease the strain on staff and budget, Duke’s Facilities Management Division built a central chilled water plant to serve the campus. Working with Trane, construction of a 10,500-ton capacity central chilled water plant began in 2000. Connections to several university buildings and the hospital loop were added in 2004. This more efficient chiller plant resulted in significant energy savings and additional cost-avoidance savings as Duke no longer needed to replace aging chillers around the campus and hospital. In March, 2006, Duke completed a second central chilled water plant, again working with Trane. This chiller plant features three 3,500-ton Trane Duplex centrifugal chillers and serves the University and hospital campus. Final combined capacity of Chiller Plants #1 and #2 will be 45,000 tons.

Results

Chiller Plant #2 uses Trane’s EarthWise™ design concept to boost overall chiller plant efficiency. Using a variable primary flow pumping system with low chilled water flow rate (1.5 GPM/ton) and delivering 40-degree chilled water temperature at 2.3 GPM per ton flow rate on the condenser, along with variable frequency drives on condenser water pumps and cooling towers, the plant delivers chilled water annually at a system energy efficiency of .70 to .95 kW per ton of cooling capacity — compared to traditional chiller plants that consume .80 to 1.2 kW per ton. The EarthWise design also saves significant construction material costs due to reduced chilled and condenser water piping and pump size, and downsized electrical service needs. The EarthWise system in Chiller Plant #2 proved so successful that Duke retrofitted Chiller Plant #1 to a variable primary flow pumping system. Chiller Plants #1 and #2 are interconnected and operate as a single plant. Buck Young of Brady Trane, Trane’s independent office in Greensboro, N.C., said, "Duke University is a great example of an owner involved in decisions regarding their total HVAC systems, working in partnership with Trane’s applications engineering expertise throughout the project’s design, construction and operational phases."

About Duke University

Duke University traces its roots to 1838. Today, the University enrolls approximately 6,300 undergraduate and 4,500 graduate students representing almost every state and about 75 foreign countries. The curriculum has expanded to include studies in biomedical engineering, public policy and microelectronics. While guided since 1859 by the motto Eruditio et Religio, or "Knowledge and Religion," Duke University continues to change to meet changing conditions.

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