What is stack ventilation and what is a design example in a tropical house?

• A. Stack ventilation uses buoyancy-driven airflow from cool lower openings to warm upper openings; examples include tall stairwells or ventilation shafts connected to rooms with high-level openings.
• B. Stack ventilation is wind-driven from high to low openings.
• C. Mechanical fans are required for stack ventilation.
• D. It relies on sealing all openings.

Answer: (A)

Stack ventilation relies on air buoyancy to move air, so warm air rises and escapes through high openings while cooler air is drawn in through lower openings. This creates a natural vertical flow without the need for mechanical fans. In a tropical house, you design to emphasize this vertical path—think of tall spaces like stairwells or dedicated ventilation shafts that connect to rooms with high-level openings. As occupants generate heat or solar heat warms interior air, the air near the ceiling becomes buoyant and exits, pulling cooler air in from below to replace it. This reduces indoor temperatures and improves comfort.

While wind can influence ventilation, stack ventilation is driven by the temperature-induced density differences rather than by wind pressure alone, and it can operate without mechanical systems. Sealing all openings would stop the airflow entirely, defeating the purpose of ventilation.