Online Optimal Ventilation Control of Building Air-conditioning Systems

This paper presents a ventilation control strategy for multi-zone variable air volume (VAV) air-conditioning systems; integrating the sequential split-range control strategy for air-handing units with an aim to optimise the fresh air flow rate by compromising the indoor air quality and energy consumption. In this strategy, a CO2-based adaptive demand-controlled ventilation scheme would employ a dynamic multi-zone ventilation equation for multi-zone air-conditioning systems, in which a CO2-based dynamic occupancy detection scheme would be used for online occupancy detection. The strategy would identify the critical zones online, and fully consider the outdoor air demand of critical zones, while, a model-based fresh air flow rate optimal control scheme is employed for VAV air-conditioning systems with the primary air handling units. An adaptive optimisation algorithm would be used for optimising the fresh air flow rate to minimise the energy consumption. The energy saving potentials in the Hong Kong climate condition by optimising fresh air ventilation and the practical implementation of the control strategy are also discussed in this paper.