In typical commercial buildings, water-cooled chilled water plants use a significant amount of energy. Their efficiency is strongly influenced by three factors: the equipment efficiency (chillers, towers and pumps); the system configuration (e.g., the pumping scheme and types of control valves); and control sequences (e.g., equipment staging and setpoints). This article presents a parametric analysis technique to optimize the control sequences of chilled water plants that has been successfully applied to dozens of projects.