Harmonizing comfort and energy: A multi-objective framework for central air conditioning systems

As the energy demand escalates with the evolution of smart buildings, the need to conserve energy and reduce consumption in central air conditioning systems—the primary energy consumers in buildings—has become increasingly critical. This study develops a multi-objective optimization framework that balances thermal comfort with energy consumption in central air conditioning systems. The system comprises cooling towers, water-cooled chillers, and air-handling units, among other components. For modeling, a mechanistic model for accurately characterizing cooling tower performance is advocated, a three-damper control strategy for air-side economizers is used, and an occupancy-dependent dynamic ventilation strategy is developed. Additionally, this work effectively separates the multi-objective optimization problem from the optimal damper control strategy issue, simplifying the solution process. Simulation results indicate that the damper control strategy adopted can reduce the fan energy consumption of air handling units by 5.622% while preserving indoor air quality. The adaptive ventilation strategy can lower overall system energy use by 10.373%. Implementing this framework not only ensures thermal comfort but also significantly lowers system energy consumption by 48.091% compared to the baseline case.