Constrained predictive control of multi-zone air-conditioning systems

Variable-air-volume (VAV) air-conditioning systems control the air temperatures inside a multi-zone building by varying the amount of air flowing into the zones. As the zone temperatures rise, the dampers in the terminal boxes open to allow more cold air into the zones, so as to maintain the zone temperatures at their set-points. When the dampers in the terminal boxes open, the static pressure in the supply duct drops, and the control system increases the speed of the supply fan in order to maintain the pressure. The opposite occurs when terminal boxes are closed. This paper explains how a constrained predictive control algorithm, that was developed by Ling (1993) to control a multi-input plant, can be used to minimise the cost of operating a multi-zone VAV system.