Analytical and experimental investigations of an air distribution system with an economizer indicated that economizers with linear dampers require less power than systems that have economizers with nonlinear dampers. It was also noted that a system with an economizer with linear dampers will require less fan speed variation to maintain system pressures constant. A linear damper is one whose free flow area varies linearly with respect to the control signal. A procedure for linearizing a nonlinear damper by means of software is presented. Energy savings may thus be achieved without capital expenditure. Several control strategies were nvestigated. The conventional strategy is to couple the outdoor air, recirculation, and discharge damper of the economizer by means of the control system. A new strategy in which only the outdoor air and recirculation dampers were coupled while the discharge damper was always fully open during operation was also investigated. A system with the new strategy required slightly less fan power. Demand control ventilation was implemented using the new control strategy and software linearized dampers. The system successfully controlled the carbon dioxide concentration in a conditioned space using a proportional integral control algorithm.

Units: Dual