Methodology development for determining long-term performance of cool storage systems from short-term tests

This paper and its companion (Elleson et al. 2002) report the results of ASHRAE Research Project RP-1004: Determining long-term performance of cool storage systems from short-term tests. The overall objective of this research was to develop a generalized methodology for determining the long-term performance of an existing cool storage system based on short-term field measurements. Specifically, this involved: i. the development of an analysis methodology for determining energy and demand savings of the cooling plant due to the cool-storage system as compared to an otherwise identical one without such a cool-storage system. The analysis was to be based as much as possible on monitored data as against conventional methods that rely on simplified calculations of "typical" days during summer and winter which are then extrapolated to the whole year; and ii. recommendations for formulating a short-term measurement and verification (M & V) plan. This includes issues such as what specific measurements to make, the time of the year in which to make them (i.e., how one season may be more suitable than another), and the duration of the short-term monitoring period. Such a methodology has been developed and tested using monitored data from three case study sites, resulting in significant advances in the analysis of in-situ cool storage system performance. This methodology will simplify the evaluation of existing cool storage systems, which will enhance the application of cool storage technology. It will also provide a basis for the development of evaluation methodologies for other technologies; for example, thermal heating storage systems used in areas where expensive electrical energy is used for heating. While the companion paper describes the validation of field data used for the performance evaluation (Elleson et al. 2002), this paper describes details of the analysis methodology and presents the results of applying the methodology to the three case study sites. Recommendations for future work are also included.