Stack Effect refers to:

Stack Effect refers to:

• A. The movement of air due to mechanical ventilation
• B. The movement of air into and out of a building due to indoor/outdoor air density differences and natural buoyancy
• C. The transfer of heat through a solid material
• D. The circulation of air exclusively through ducts

Answer: (B)

Stack effect is the buoyancy-driven movement of air caused by density differences between indoor and outdoor air, usually from temperature differences. Warm indoor air is less dense and tends to rise to the upper parts of a building, creating slight overpressure at the top and underpressure at the bottom. That pressure difference draws cooler outside air in at lower levels and lets warmer inside air escape at higher levels. This natural air movement is distinct from mechanical ventilation, heat transfer through solids, or air circulating exclusively through ducts. In practice, stack effect can lead to energy losses and unwanted air leaks in tall or tightly built structures, especially when there are openings at multiple levels and a sizable temperature difference.

Stack effect is the buoyancy-driven movement of air caused by density differences between indoor and outdoor air, usually from temperature differences. Warm indoor air is less dense and tends to rise to the upper parts of a building, creating slight overpressure at the top and underpressure at the bottom. That pressure difference draws cooler outside air in at lower levels and lets warmer inside air escape at higher levels. This natural air movement is distinct from mechanical ventilation, heat transfer through solids, or air circulating exclusively through ducts. In practice, stack effect can lead to energy losses and unwanted air leaks in tall or tightly built structures, especially when there are openings at multiple levels and a sizable temperature difference.