Energy use and economic comparison of chilled-water pumping system alternatives

William P. Bahnfleth, Eric B. Peyer, James B. Rishel

Research output: Contribution to journalConference articlepeer-review

29 Scopus citations


Variable primary flow chilled water pumping systems allow flow through chiller evaporators to vary in response to changes in load. Variable primary flow proponents claim that this approach uses less energy and is more economical than other pumping schemes, in particular, the well-established primary/secondary system. This paper investigates these claims via a parametric modeling study. Parameters varied included plant cooling load profile and climate, number of chillers in the plant, chilled water temperature difference vs. load, and others. Construction cost and operating cost differences were calculated and systems were compared on a life-cycle cost basis. Variable flow, primary-only systems reduced total annual plant energy use by 2%-5%, first cost by 4%-8%, and life-cycle cost by B%-5% relative to equivalent primary/ secondary systems for the assumptions and range of parameters considered.

Original languageEnglish (US)
Pages (from-to)198-208
Number of pages11
JournalASHRAE Transactions
Volume112 PART 2
StatePublished - Oct 31 2006
Event2006 Annual Meeting of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, ASHRAE - Quebec City, QC, Canada
Duration: Jun 24 2005Jun 28 2005

All Science Journal Classification (ASJC) codes

  • Building and Construction
  • Mechanical Engineering


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