On-demand control of ventilation systems

In this paper a new strategy for controlling ventilation systems is described. The strategy provides fresh air at a flow rate proportional to an estimate of the rate at which occupants generate carbon dioxide. Thus, the ventilation rate is nearly proportional to the occupant density even under transient conditions. It is shown that this control strategy is a concentration-limiting strategy. This strategy is compared to a concentration regulating strategy in a simulation. The new strategy is shown to respond rapidly to a change in the occupant density and to keep the concentration at or below a threshold.