What occurs to warm air inside a building when it’s cold outside?

The correct understanding of how warm air behaves in relation to cold outdoor temperatures is captured in the choice that states warm air escapes through the top while cold air enters at the bottom. This principle is rooted in basic thermodynamics and the properties of air.

When it is cold outside, heated air inside a building naturally rises due to its lower density compared to cooler outside air. As the warm air ascends, it seeks exit points often located higher in the structure, such as gaps, cracks, or ventilation systems. This movement creates a pressure differential which allows colder, denser air to enter from lower levels, replenishing the space left by the escaping warm air. This phenomenon is a key characteristic of how air circulation typically occurs in buildings, particularly during cold weather.

Understanding this airflow pattern is critical for effective building design and energy efficiency measures; it highlights the importance of maintaining airtightness to retain heated air and minimize energy loss.