This paper describes a case study of the model-based condenser water temperature setpoint control for a chiller plant with multiple chillers and cooling towers. The plant was modeled using the Modelica Buildings library. Both the supervisor control and local feedback loop controls were modeled to more realistically represent the real system. The total energy consumptions and computing times under different optimization strategies were compared. The result shows that the daily optimization can provide similar energy saving with significantly less computing timecompared to the hourly optimization.