Abstract
The energy consumption and resultant CO_2 emission of a commercial ice thermal storage unitary air conditioner are calculated by a simple simulation program which is based on its performance data released by its manufacturer, and hourly averaged cooling load and outdoor temperature data for an average office building in Tokyo. The result shows that the cooling mode of operation utilizing nighttime ice thermal storage is not energy saving in comparison with the conventional cooling mode of operation without thermal storage. This fact is also shown by discussion of energy consumption based on a criterion derived in this study.