Abstract: A system for controlling the operation of a plurality of dampers serving ventilation apertures in the structure of a building, which system comprises a plurality of actuators, one or more to be associated with each damper and to actuate the damper between an open and a closed position; the actuators incorporating means for receiving a signal from a controller, for identifying that that signal contains instructions relevant to the damper which that actuator actuates; the plurality of actuators being adapted to be connected in series with the controller via a single connecting cable.