Analysis of the impact of the parameters of outside air on the condition of indoor air

The article presents the impact of external conditions on the parameters of the air inside the flats and hybrid ventilation. In the vast majority of existing multifamily buildings, as well as in many newly built ones, the way of air exchange is natural ventilation. The air exchange in this system is the result of the temperature difference in the outside of the building and in the ventilation duct as well as the pressure difference caused by the wind. The way to strengthen the exchange of indoor air is to use the hybrid ventilation by using a fan to assist natural air flow in the “no wind” periods. When designing the natural ventilation installation, the extreme conditions outside the building are assumed, not including air parameters changing. This article attempts to identify the conditions of atmospheric air which cause the disturbances of exchange indoor air and it attempts to decide when a fan should work to assist natural ventilation.