A Case Study on Condenser Water Supply Temperature Optimization with a District Cooling Plant

Kathryn Hinkelman, Jing Wang, Chengliang Fan, Wangda Zuo, Antoine Gautier, Michael Wetter, Nicholas Long

Research output: Contribution to conferencePaper


District cooling (DC) continues to proliferate due to increasing global cooling demands and economies of scale benefits; however, most district-scale modeling has focused on heating, and to the best of our knowledge, researchers have yet to model cooling plants featuring waterside economizers in DC settings. With the popular Modelica Buildings library expanding its capabilities to district scale, this study is one of the first to demonstrate how the open-source models can be used for detailed energy and control analysis of a DC plant. For a real-world case study, we developed and calibrated high-fidelity models for a DC system central plant at a college campus in Colorado, USA, and we optimized the condenser water supply temperature (CWST) setpoint for a DC plant across multiple time horizons using the Optimization library in Dymola. Results indicate that annual CWST optimization saves 4.7% annual plant energy, with less than 1% of additional energy savings gained through daily optimization. This confirms previous studies' findings that high frequency CWST optimizations are not necessary for the studied system.
Original languageAmerican English
Number of pages9
StatePublished - 2021
Event14th Modelica Conference 2021 - Linkoping, Sweden
Duration: 20 Sep 202124 Sep 2021


Conference14th Modelica Conference 2021
CityLinkoping, Sweden

NREL Publication Number

  • NREL/CP-5500-81665


  • chiller plant
  • district cooling
  • Modelica Buildings library
  • optimization
  • waterside economizer


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