A single-flow ventilation system for premises comprising a plurality of rooms (102, 104), the single-flow ventilation system comprising: - A fan; - An extraction flow rate centralization device comprising: ∘ a first air intake configured to be connected to a first room of the plurality of rooms, ∘ a second air intake configured to be connected to a second room of the plurality of rooms, and ∘ an air outlet connected to the fan by an outlet duct; - A first means for regulating an air flow rate circulating in the first air intake; - A second means for regulating an air flow rate circulating in the second air intake, - Air measuring means arranged to perform a measurement of the air in the first air intake, and a measurement of the air in the second air intake; - A control device configured to control the first means for regulating the air flow rate circulating in the first air intake according to information communicated by the air measuring means, and to control the second means for regulating the air flow rate circulating in the second air intake according to information communicated by the air measuring means, the air measuring means comprising a sensor for measuring a quantity indicative of a ventilation requirement, such as a CO2 and/or humidity and/or VOC sensor, the sensor being configured to be communicated with the air of the first or the second air intake, characterized in that the sensor is a common sensor configured to be communicated alternately with the air of the first air intake and the air of the second air intake. - A fan; - An extraction flow rate centralization device comprising: ∘ a first air intake configured to be connected to a first room of the plurality of rooms, ∘ a second air intake configured to be connected to a second room of the plurality of rooms, and ∘ an air outlet connected to the fan by an outlet duct; ∘ a first air intake configured to be connected to a first room of the plurality of rooms, ∘ a second air intake configured to be connected to a second room of the plurality of rooms, and ∘ an air outlet connected to the fan by an outlet duct; - A first means for regulating an air flow rate circulating in the first air intake; - A second means for regulating an air flow rate circulating in the second air intake, - Air measuring means arranged to perform a measurement of the air in the first air intake, and a measurement of the air in the second air intake; - A control device configured to control the first means for regulating the air flow rate circulating in the first air intake according to information communicated by the air measuring means, and to control the second means for regulating the air flow rate circulating in the second air intake according to information communicated by the air measuring means, the air measuring means comprising a sensor for measuring a quantity indicative of a ventilation requirement, such as a CO2 and/or humidity and/or VOC sensor, the sensor being configured to be communicated with the air of the first or the second air intake, characterized in that the sensor is a common sensor configured to be communicated alternately with the air of the first air intake and the air of the second air intake.