Although thermal-energy storage (TES) systems for peak load shifting are now in the market, very few performance testing and evaluation procedures have been developed. Measurements were made to quantify space-cooling, space-heating, and domestic water-heating but the emphasis was on space-cooling performance of the unit. The TES system was tested over a wide range of indoor and outdoor conditions to determine parameters such as ice building rate, compressor power, cooling rate, heating rate, desuperheater rate, energy efficiency ratio, and power consumption factor.