An adaptive demand-controlled ventilation strategy with zone temperature reset for multi-zone air-conditioning systems

In air-conditioning systems serving multiple zones, conventional ventilation strategies often result in over-ventilation in some zones with under-ventilation in the other zones when the heating/cooling load and occupancy profiles of zones differ greatly. This article presents an adaptive demand-controlled ventilation (DCV) strategy for multi-zone air-conditioning systems, which employs real-time occupancy identification using the dynamic multi-zone ventilation equation and zone temperature set-point reset of critical zones. The strategy identifies the critical zones, and fully considers the outdoor air demand of critical zones and the unvitiated outdoor air in the re-circulated air from the other zones. The air temperature reset of critical zones results in the increase of their supply air fractions and therefore the amount of outdoor air delivered to the critical zones. Consequently the total outdoor airflow demand and the overall energy consumption are reduced while the ventilation of critical zones is satisfied. This adaptive DCV strategy is validated by comparing its energy and environmental performances with other typical ventilation strategies under various weather conditions.