The study results reported these systems reduced the total annual plant energy by 3% to 8%, initial cost by 4% to 8%, and life cycle cost by 3% to 5%, relative to conventional constant primary flow/variable secondary flow chilled water systems. The report said several factors influenced energy savings and economic benefits, including the number of chillers, climate, and chilled water temperature differential.

The study compared the energy use of primary flow chilled water systems with that of other common system types including: constant flow/primary-only chilled water systems; constant primary flow/variable secondary flow chilled water systems; and primary/secondary chilled water systems with a check valve installed in the decoupler.

The final report can be downloaded from the ARTI Web site at www.arti-21cr.org.