In nuclear industry, the response of a ventilation network to accidental disturbances, either mechanical (fan failure, damper blockage,…) or thermal (fire…) is difficult to evaluate when the network becomes complex. In order to determine and analyze the consequences of these disturbances on the radioactive materials confinement, a code called SIMEVENT has been developed. Among the external parameters likely to affect a ventilation network, the wind effect is actually basically modeled, due to a lack of qualified data concerning the wind impact on complex building’s geometries and the interaction between wind and chimney exhaust. In view of the networks complexity and the installations diversity, a research program including experimental and model studies has first been launched to assess the pressure coefficients due to wind on different chimneys and reference buildings geometries. Different chimney terminals have been placed in a wind-tunnel (the variables are the incline angle, wind velocity and air flow in the duct); for each angle, the evolution of the pressure coefficient versus wind velocity is determined and is characteristic of a chimney terminal geometry. Two types of scale-model have been chosen for representing either nuclear power plants or plants and laboratories buildings. The different values of wind pressure coefficients have been measured on both scale-models placed in a wind-tunnel. The modelling of wind influence on the networks consists then in fixing measured wind pressure coefficients at all air inlets and outlets in the code; then, SIMEVENT calculates the consequences on pressure and flow rate values inside the whole building, for the normal operating mode or degraded one’s (such as fan failure or appearance of fissures on walls). Finally, the use of such a code allows the evaluation of contamination release in environment due to degraded operating modes in ventilation networks, integrating the influence of wind.