Method for regulating the rotation speed of an exhaust air extraction ventilator of an installation comprising a plurality of extract units connected to a common collector through conduits (6, 9), wherein: - in an initial step, -- from data representative of the installation, a first flow of the installation is determined, and at this first flow, a load loss, called theoretical load loss, is calculated, between each extract unit and the ventilator, -- an extract unit, called the most disadvantaged unit, is determined, having the maximum theoretical load loss, and -- a load loss coefficient (ζ) of the installation between the most disadvantaged unit and the ventilator from cross-sectional data (S1, S2) of the collector, -- a load loss coefficient between said the most disadvantaged unit and the ventilator is determined for at least two other staged flows in a range of flows of the installation, - in a second step, at each instant, -- a measured flow (Qmes) of the installation is estimated, -- a pressure, called calculated pressure (Pbouche) is calculated, to the right of the most disadvantaged unit from the measured flow and the load loss coefficients of the installation, and -- the rotation speed of the ventilator is regulated according to a difference between the calculated pressure and a setpoint pressure (Pc). - in an initial step, -- from data representative of the installation, a first flow of the installation is determined, and at this first flow, a load loss, called theoretical load loss, is calculated, between each extract unit and the ventilator, -- an extract unit, called the most disadvantaged unit, is determined, having the maximum theoretical load loss, and -- a load loss coefficient (ζ) of the installation between the most disadvantaged unit and the ventilator from cross-sectional data (S1, S2) of the collector, -- a load loss coefficient between said the most disadvantaged unit and the ventilator is determined for at least two other staged flows in a range of flows of the installation, -- from data representative of the installation, a first flow of the installation is determined, and at this first flow, a load loss, called theoretical load loss, is calculated, between each extract unit and the ventilator, -- an extract unit, called the most disadvantaged unit, is determined, having the maximum theoretical load loss, and -- a load loss coefficient (ζ) of the installation between the most disadvantaged unit and the ventilator from cross-sectional data (S1, S2) of the collector, -- a load loss coefficient between said the most disadvantaged unit and the ventilator is determined for at least two other staged flows in a range of flows of the installation, - in a second step, at each instant, -- a measured flow (Qmes) of the installation is estimated, -- a pressure, called calculated pressure (Pbouche) is calculated, to the right of the most disadvantaged unit from the measured flow and the load loss coefficients of the installation, and -- the rotation speed of the ventilator is regulated according to a difference between the calculated pressure and a setpoint pressure (Pc). -- a measured flow (Qmes) of the installation is estimated, -- a pressure, called calculated pressure (Pbouche) is calculated, to the right of the most disadvantaged unit from the measured flow and the load loss coefficients of the installation, and -- the rotation speed of the ventilator is regulated according to a difference between the calculated pressure and a setpoint pressure (Pc).