In the revised building code of Japan enforced in 2003, mechanical ventilation available for continuous operation has been mandatory in principle mainly for improving healthy condition. However, the rule and the spread of mechanical ventilation systems would be a problem from the view point of energy saving, when the energy conserving measures would be introduced effectively in other components like HVAC, hot water systems, lighting, etc. On the basis of the above recognition, the utilization of natural energy, i.e. wind power, for ventilation is tried by developing a hybrid ventilation system for multifamily dwellings. For the utilization of the wind pressure, a self-regulated damper with variable airflow resistance depending on the pressure difference is developed and its characteristics are investigated. In this paper, firstly, the system is described and the characteristics of its components are quantitatively evaluated. Secondly, wind-driven ventilation behavior of the system is modeled by a network of constant and variable airflow resistance on the basis of components' characteristics. Thirdly, the network model is validated referring the experimental data.
