So referred to as Tesla valves can let extra air in a single route than the opposite, with out shifting components:
https://en.wikipedia.org/wiki/Tesla_valve
With buildings, which means that it’s doable to stroll by means of a working valve-doorway even when doorways are open or not there.
Possibly place them in line with typical wind instructions or for warmth associated motion up, low and higher flooring entrances having them in appropriate instructions.
This additionally might have some relation to crowd’s stampede hazard.
