Natural VentilationEnter the room, the two openings, the wind and the temperatures. Get the airflow from wind and from the stack effect, the air changes per hour, and whether it meets the ventilation rate for the room's use.

Openings are the free (openable) areas, not the window size. The stack height is the vertical distance between the centres of the inlet and the outlet. Wind speed is measured at the window; city streets are calmer than the weather report.