Optimum design and operation of ice-storage air-conditioning systems under Australian TOU tariffs

Ice-storage means the manufacture of ice by refrigeration systems during off-peak periods, to be re-melted to meet cooling requirements during peak demand periods. This paper deals with the economics of using ice-storage systems in Australian commercial buildings and with the role that the differently-shaped time-of-use electricity tariffs on offer in Sydney and Melbourne have on the optimum system design. Using mathematical programming techniques, the optimum store control strategy is investigated for different seasonal and load conditions. In both cities, the use of the ice-storage concept is shown to reduce overall air-conditioning costs significantly. The extra capital costs are paid back with savings in electricity in less than two years for most of the cases investigated.