System for managing fan units in a building comprising several groups of indoor spaces and said fan units, each group of indoor spaces having an associated fan unit extracting stale air from the indoor spaces, the fan unit including an air extraction support system, the management system comprising a global management unit and a plurality of local data centralisation units, the global management unit being adapted to communicate with the plurality of local data centralisation units to control the fan units, each local data centralisation unit being associated with at least one fan unit, - the global management unit of the building including: ∘ a communication module adapted to receive a plurality of data, the plurality of data including data exterior to the building and at least one local operating parameter of a fan unit; ∘ a calculation module adapted to determine at least one global operating parameter of the fan units from the plurality of data received by the communication module of the global management unit; and ∘ a control module adapted to operate the fan units based on said at least one global operating parameter determined by the calculation module; and - each of the local data centralisation units including: ∘ a communication module adapted to receive data associated with the concentration of the at least one pollutant in at least one of the indoor spaces; and ∘ a calculation module adapted to determine the local operating parameter from data associated with the group of indoor spaces received by the communication module, characterised in that said calculation module of each local data centralisation unit is able to average the data received by type of pollutant on at least one of said groups controlled by a single fan unit, one of said local data centralisation units being able to issue control commands to said global management unit as a function of said calculated averages of pollutants and of limit thresholds deemed admissible which are capable of being set in said calculation module. - the global management unit of the building including: ∘ a communication module adapted to receive a plurality of data, the plurality of data including data exterior to the building and at least one local operating parameter of a fan unit; ∘ a calculation module adapted to determine at least one global operating parameter of the fan units from the plurality of data received by the communication module of the global management unit; and ∘ a control module adapted to operate the fan units based on said at least one global operating parameter determined by the calculation module; and ∘ a communication module adapted to receive a plurality of data, the plurality of data including data exterior to the building and at least one local operating parameter of a fan unit; ∘ a calculation module adapted to determine at least one global operating parameter of the fan units from the plurality of data received by the communication module of the global management unit; and ∘ a control module adapted to operate the fan units based on said at least one global operating parameter determined by the calculation module; and - each of the local data centralisation units including: ∘ a communication module adapted to receive data associated with the concentration of the at least one pollutant in at least one of the indoor spaces; and ∘ a calculation module adapted to determine the local operating parameter from data associated with the group of indoor spaces received by the communication module, ∘ a communication module adapted to receive data associated with the concentration of the at least one pollutant in at least one of the indoor spaces; and ∘ a calculation module adapted to determine the local operating parameter from data associated with the group of indoor spaces received by the communication module,