A single-flow ventilation system for premises comprising a plurality of rooms , 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 . <EOS>