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What phenomenon describes heat being exhausted from the top of a building due to stratification?
Infiltration
Stack effect
Ventilation
Convection
The correct answer is: Stack effect
The stack effect is the phenomenon that describes how heat naturally rises and, as a result, is exhausted from the upper portions of a building. This occurs due to the difference in temperature and pressure between the warmer air inside a building and the cooler air outside. As warm air rises, it creates a pressure difference that draws cooler air into the lower levels of the structure, effectively replacing the rising warm air. In buildings, this effect is particularly prominent in tall structures or those with large temperature differentials between interior and exterior spaces. The stack effect not only helps with natural ventilation but can also influence heating and cooling demands, making it an important concept in energy auditing. Infiltration refers to the unintentional or accidental introduction of outside air into a building, which can influence energy efficiency but does not describe the upward movement of warm air. Ventilation generally relates to the controlled introduction of outside air for purposes of maintaining air quality and comfort and does not specifically address heat stratification in buildings. Convection, while a process involving the transfer of heat through fluid motion (including air), is more about how heat moves within a space rather than specifically describing the mechanism of heat leaving a building from the top as seen in the stack effect.