A near-optimal global set point control method that can be implemented in an energy management system's (EMS) DDC controller is described in this paper. Mathematical models are presented for the power consumption of electric chillers, hot water boilers, chilled and hot water pumps, and air handler fans, which allow the calculation of near-optimal chilled water, hot water, and coil discharge air set points to minimize power consumption, based on data collected by the EMS. Also optimized are the differential and static pressure set points for the variable speed pumps and fans. A pilot test of this control methodology was implemented for a cooling plant at a pharmaceutical manufacturing facility near Dallas, Texas. Data collected at this site showed good agreement between the actual power consumed by the chillers, chilled water pumps, and air handlers and that predicted by the models. An approximate model was developed to calculate real-time power savings in the DDC controller. A third-party energy accounting program was used to track savings due to the near-optimal control, and results show a monthly KWH reduction ranging from 3% to 14%.

Units: I-P