This study combines an energy simulation program with a hybrid optimization algorithm to identify the optimal settings and minimize the energy consumption of chilled water system. This study employed EnergyPlus, a flexible and highly accurate energy simulation program, to construct the model. To determine the optimal temperature settings for chilled and cooled water for chilled water system, this model used a hybrid optimization algorithm that combines the particle swarm optimization algorithm and the Hooke-Jeeves algorithm. We selected four days in summer and four days in winter to conduct the optimization. The results indicated that the optimized settings reduced the total energy consumed by the chilled water system by 9.4% in summer and 11.1% in winter compared to conventional settings. (C) 2012 Elsevier B.V. All rights reserved.