Buoyancy-driven ventilation increases with greater temperature difference, and increased height between the higher and lower apertures in the case of displacement ventilation. When both high and low level openings are present, the neutral plane in a building occurs at the location between the high and low openings at which the internal pressure will be the same as the external pressure (in the absence of wind).
Buoyancy-driven ventilation is more effective when there's a greater temperature difference and higher vertical separation between high and low air inlets in displacement ventilation systems. The neutral plane within a building is located at the point where the internal pressure matches the external pressure, without wind influence.