An ice thermal energy storage is adopted in the HVAC plant of a supermarket, to shave peaks in electricity use. Ice is formed at night-time by employing the commercial refrigeration system, which is considerably part-loaded during the shop closing time. During daytime, the thermal storage is discharged and operated in parallel to a water chiller, to produce chilled water for air conditioning purposes. The whole system is modelled, to look for the most effective control rule in an attempt to match energy efficiency and the need to comply with a threshold in the electricity use