Energy and Cost Assessment of Packaged Ice Energy Storage Implementations Using OpenStudio Measures

As renewable portfolio standards enforce the expansion of renewables on the U.S. grid in the coming years, old storage technologies must be re-evaluated for a dynamic, interactive future grid. Ice thermal storage, traditionally for diurnal load shifting on large central chiller plants, is also viable in packaged devices for most buildings that lack central plants. However, modeling of these unitary thermal storage systems (UTSS) has been very limited to-date. To help make packaged thermal storage modeling more accessible, this paper presents a recently developed OpenStudio measure for rapid analysis of UTSS. Using this measure, we assess the UTSS implementation in new and retrofit retail buildings with both packaged single zone air conditioners (PSZAC) and packaged variable air volume (PVAV) systems. Each implementation is evaluated on annual energy use, fan energy use, load shifting efficiency, daily unused ice availability, and potential cost savings under various time-of-use rates. Deficiencies with schedule-based control are highlighted by comparing the daily unused ice and the cooling-electricity load duration curve. Annual energy use increases by 1.2–3.7%, but on-peak electric demand is reduced by 32.2–36.6%.