Natural ventilation of a room with vents at multiple heights

The natural ventilation of a room with a source of uniformly distributed heating at the base andwith vents at multiple heights is investigated both theoretically and experimentally. It is shown that the impact of additional vents can be predicted by determining the height of neutral buoyancy. As a room is heated it heats up to a uniform state and the relative height of neutral buoyancy depends on the ratio of the upper and lower vent areas. When a simple additional intermediate level vent is introduced a unique solution can be used to predict the resulting air flow. However, when an intermediate level vent is connected to a stack, the room can respond in two fundamentally different modes, where the stack can act as an inflow or outflow.