Optimizing the Design of Chilled Water Plants for Commercial Building Energy Systems (LB-17-005)

Design of chilled water plants has a very large impact on building energy uses and energy operating costs. This paper proposes a design tool for optimal design of chilled water plants. The tool that integrates system models with a genetic algorithm optimization solver minimizes the life cycle cost by finding the design variables such as chilled water and condenser piping diameters, chilled and condenser water temperature differences and chilled water supply temperature. The proposed modeling methods depend on detailed cooling load analysis and head and energy calculations. The pump head calculations including piping, all fittings, valves, and devices are achieved by using the Darcy-Weisbach equation with given flow parameters. The energy calculations are done by using generic chiller, fan, and pump models. The hourly cooling loads need to be obtained from any energy simulation software. The method is tested on an existing three-story, eighty-eight thousand square foot building.