This pilot study evaluates the overall energy performance of indirect/direct evaporative cooling (IDEC) in AC cooling applications under extreme hot and humid climatic conditions. The pilot scope included the installation of a 5 ton, IDEC unit in hybrid (tandem) operation with an existing 5 ton conventional DX package unit to provide comfort cooling to a house located in Dhahran, Saudi Arabia. The house cooling demand was met by the IDEC unit 45% of the cooling season hours, while the remaining 55% were met by the DX package unit. The overall IDEC / DX hybrid system had a collective weighted annual average Energy Efficiency Ratio (EER) of 15.1, achieving 26% annual energy savings compared to using the DX package unit for the entire cooling season alone. The IDEC unit water usage was recorded as a function of the outdoor dry bulb air temperatures and was observed to have a signature range of 1.1 GPH to 19.6 GPH for outdoor temperatures of 66 °F to 108 °F respectively. Results obtained provide more insight to the HVAC community for the opportunities and limitations of the IDEC AC applications under extreme hot and humid climates.