Energy flexibility assessment of commercial buildings in cooling season based on advanced modeling of rooftop units

Abstract

Buildings with air-conditioning systems can support power grid operators to manage electricity surpluses and deficits from renewable energy sources through demand response. However, the flexibility potential largely depends on the building usage and technologies employed. In this respect, a lack of studies on the flexibility of commercial buildings equipped with rooftop units is evident. To fill this gap, this study investigates the energy f lexibility of a standardized commercial building in a cooling-dominated zone using an experimental-based rooftop unit model. Three price-based energy flexibility strategies are analyzed: one involving the deactivation of cooling systems and two based on adjustments to the zone temperature setpoint. A dynamic simulation of the building and its integrated cooling system is conducted, evaluating changes in indoor air temperature and relative humidity profiles, as well as occupant comfort indicators. Results indicate that partial deactivation of rooftop units can achieve up to 50 % daily peak shaving, with a maximum deviation in the indoor air temperature of 4 ◦ C during the final part of the working day, and a 22.72 % reduction in seasonal energy consumption. Increasing the temperature setpoint by 2 ◦ C enhances annual energy savings by an additional 5.2 %, but results in up to a 13 % rise in discomfort hours. Conversely, lowering the setpoint by 2 ◦ C in response to high electricity availability from renewable sources increases peak demand significantly—from 7.7 kW to 25.3 kW (more than a threefold rise)—while maintaining indoor comfort and yielding a 43.6 % increase in seasonal energy consumption. A high sensitivity in both energy savings and occupant discomfort is observed with an additional 1 C deviation in the indoor air temperature, resulting in approximately a 16 % increase in energy savings and a 20 % rise in discomfort hours. This study highlights that commercial buildings offer significant potential for energy f lexibility in cooling-dominated regions, but strategies must be carefully customized to minimize the impact on occupant comfort.