On ventilation of a heated room through a single doorway

First laboratory experiments are presented, the aim is to examine the transient filling of a room of buoyant fluid when a doorway connects the room to a large reservoir of dense fluid. A model of the transient exchange flow is then presented, it is in accordance with the experimental results.
A layer of air, warmer than the exterior must be maintained above a cold layer near the floor to prevent the heat supplied to the room to be lost through the doorway.