This report presents results of an investigation of the performance and control characteristics of the individual components and the cooling system as a whole at the Dallas/Fort Worth (D/FW) airport. One goal was to identify appropriate computer simulation models of the plant equipment to be used in evaluating system retrofits and proper control strategies. Much data was available from the the D/FW data acquisition system for validating the component models. A second goal was to document the performance differences associated with the use of chillers operated with variable speed control with that for fixed speed with vane control. The performance and control characteristics of the D/FW cooling system were also studied. Finally, methodologies useful for on-line optimal control of the equipment were developed.