GARD worked on a project to add thermal energy storage system models to the EnergyPlus building simulation program. This work enhanced the ability of EnergyPlus to accurately model a wide range of building and energy system configurations. GARD consulted with TES manufacturers and industry experts to determine the significant performance parameters that need to be included in the model, along with the appropriate algorithms to be used. Appropriate changes were then made to implement the model in EnergyPlus.