Abstract: A method for controlling a ventilation system having an array of fans drawing air from an enclosed space, the array of fans having a set of variable speed fans, and a control unit to actuate the fans according to a plurality of ventilation levels, a respective total flow rate value of air flowing in the enclosed space being associated to each ventilation level, each ventilation level distinguished by a respective number of switched-on fans and a respective rotation speed of the variable speed fans, involves determining an actual value of static pressure associated with the array of fans, and calculating a provisional value of the rotation speed that maximizes static efficiency of the variable speed fans at the actual value of static pressure. The method further involves, for each ventilation level, calculating and storing the respective associated rotation speed and number of switched-on fans, and actuating the array of fans.