Load decomposition: A conceptual framework for design and control of thermal energy storage systems in buildings

Abstract

This work proposes a load decomposition framework for the characterization of thermal energy storage systems (TES) in buildings. This conceptual framework makes it possible to rapidly obtain an estimate of the required rating for the primary equipment and the storage device. The proposed approach employs mathematical methods from signal processing to break down the building load signal into two sub-signals: (a) a primary load provided by the primary production system, and (b) a balancing load provided by the storage system. This information is used to form a Pareto set of solutions that expresses the trade-off between the storage capacity and the primary system size, and hence, comprises the peak shaving potential of any given configuration. A simple decomposition method based on the concept of ”moving average” is tested within this framework on a representative energy model of an office building in the region of Montréal, Québec (QC). The Pareto set is shown to offer a wide range of design and operation solutions for peak shaving, from small water tanks to large underground reservoirs. The results provide clear evidence that TES system not only contributes to peak shaving and load shifting, but also to significantly reduce the primary production unit size.