An Overall Assessment of Ice Storage Systems for Residential Buildings

The recent availability of variable electric energy and demand rates for residential buildings is providing incentives for the application of thermal storage for cooling that previously has been limited to commercial buildings. This is particularly relevant for hot climates where air-conditioning (A/C) use is the primary cause for peak electricity demand. Thermal storage allows consumers to store “cooling” when demand is low and minimize operation of the A/C during peak periods. From an economic perspective, the use of storage can significantly reduce operating costs depending on the utility rate incentives. In addition, storage can lead to a reduction in the installed cost of the primary cooling equipment because of a reduction in the peak equipment cooling requirement. However, this reduced equipment cost is counteracted by the additional costs required for storage and a secondary loop. This paper considers the overall economics associated with a packaged A/C integrated with ice energy storage for residential cooling applications. The evaluation was performed using a model of the proposed system that estimates system performance and operating cost over a cooling season for different locations and utility rates and using a generalized control strategy presented in a companion paper. The proposed system is compared to a conventional spilt system A/C in terms of initial cost, operating cost, and economic payback. In addition, we investigate the trade-off between equipment cooling capacity and storage size to determine minimum payback period for each situation. The optimization results show that the systems with the shortest payback period have initial costs that are very similar to the baseline system. In addition, the payback periods are attractive in locations with favorable utility rates and long cooling seasons (i.e., hot climates).