The results of the analysis of the design of the ventilation system of a section of a ten-story residential building, including three- and one-room apartments, using a mathematical model are presented. The equations of the ventilation system model are based on the hydraulic network graph. The model includes equations for the balance of air flow rates for the nodes of the graph and equations for changing the pressure for the links. It is shown that it is impossible to provide the required air flow rates simultaneously in all apartments using natural ventilation, including in the presence of wind. The model allows you to compare different ways to improve the performance of the ventilation system. As an example, two options for using exhaust fans that remove air from an attic space (hybrid ventilation) are considered. When using one fan, the mode of its operation is determined by the apartments, the windows of which are into the area of the aerodynamic shadow. As a result, the ventilation air rate in other apartments can significantly exceed the required ones. To improve the uniformity of air exchange, it is advisable to combine the ventilation ducts of apartments, oriented mainly at one building facade, into separate zones, each of which is served by its own fan. © 2023 Author(s).