Ventilation system for a building, comprising: - air inlet means with a controllable air passage cross-section, wherein an air stream flows from the outside to the inside of the building through each of the air inlet means with a controllable air passage cross-section, - at least one air evacuation means, - control means (6, 8, 9) which cooperate with the air inlet means with a controllable air passage cross-section, wherein the control means (6, 8, 9) control the opening and closing of the air inlet means with a controllable air passage cross-section, - at least one data input means (17a, 17b, 17c, 17d, 22, 23) for data relating to at least one parameter of the environment inside the building and/or to at least one parameter of the environment outside the building and/or to at least one presence inside the building, which data are acquired by way of at least one sensor (17a, 17b, 17c, 17d) and/or through a man-machine interface and/or by way of a communication network, wherein ∘ the control means (6, 8, 9) comprise electronic control units, ∘ the electronic control units electrically control the opening and closing of the air inlet means with a controllable air passage cross-section in dependence on at least one input datum acquired by said at least one data input means (17a, 17b, 17c, 17d, 22, 23), so as to adjust the opening of the air passage cross-section of the air inlet means with a controllable air passage cross-section, ∘ each air inlet means with a controllable air passage cross-section is arranged at a wall of the building so as to establish direct fluidic communication between the outside and the inside of the building, ∘ the control means (6, 8, 9) also comprise a central control unit which communicates with the electronic control units, and local control units which communicate with the electronic control units, characterised in that the activation of one of the local control units by the user takes priority over the central control unit so as to control the opening or closing of at least one of the air inlet means with a controllable air passage cross-section, and in that the activation of one of the local control units directly controls at least one of the electronic control units of the air inlet means with a controllable air passage cross-section in dependence on a selection by the user, by inhibiting a command emitted by the central control unit or disregarding a datum coming from the sensor (17a, 17b, 17c, 17d) of the data input means (17a, 17b, 17c, 17d, 22, 23). - air inlet means with a controllable air passage cross-section, wherein an air stream flows from the outside to the inside of the building through each of the air inlet means with a controllable air passage cross-section, - at least one air evacuation means, - control means (6, 8, 9) which cooperate with the air inlet means with a controllable air passage cross-section, wherein the control means (6, 8, 9) control the opening and closing of the air inlet means with a controllable air passage cross-section, - at least one data input means (17a, 17b, 17c, 17d, 22, 23) for data relating to at least one parameter of the environment inside the building and/or to at least one parameter of the environment outside the building and/or to at least one presence inside the building, which data are acquired by way of at least one sensor (17a, 17b, 17c, 17d) and/or through a man-machine interface and/or by way of a communication network, ∘ the control means (6, 8, 9) comprise electronic control units, ∘ the electronic control units electrically control the opening and closing of the air inlet means with a controllable air passage cross-section in dependence on at least one input datum acquired by said at least one data input means (17a, 17b, 17c, 17d, 22, 23), so as to adjust the opening of the air passage cross-section of the air inlet means with a controllable air passage cross-section, ∘ each air inlet means with a controllable air passage cross-section is arranged at a wall of the building so as to establish direct fluidic communication between the outside and the inside of the building, ∘ the control means (6, 8, 9) also comprise a central control unit which communicates with the electronic control units, and local control units which communicate with the electronic control units,