This paper summarizes the results of field testing to evaluate the performance of simplified and optimal control strategies for shifting peak cooling loads and reducing building energy costs through the utilization of both the passive and active thermal energy storage systems for an elementary school in Colorado. In particular, the performance of precooling of building thermal mass as well as real-time model-based predictive optimal controls is evaluated.The results indicate that the school is saving roughly 47% on its annual electricity costs by utilizing the TES operated using their optimal control strategy.Units: Dual