This paper describes research associated with performance evaluation of electrically charged thermal energy storage room-size units in accordance with ASHRAE Standard 94.2. A calorimeter chamber was designed, fabricated, instru­mented and calibrated. Eight different room-size units, with charging rates ranging from 2 to 6 kW, were tested under various conditions. In addition to the measurements specified by the Standard, other measurements were obtained and analyzed in order to diagnose the behavior of the calorimeter and the units during testing. In general, good quality was achieved as evidenced by the fact that the calculated thermal output of a particular unit, based on test measurements, typically differed from the measured electrical input by no more than 2 percent at the conclusion of the test.