Which term describes the unintentional flow of air that carries indoor heat outside?

The term that describes the unintentional flow of air that carries indoor heat outside is exfiltration. Exfiltration specifically refers to the process by which warm indoor air escapes to the outside environment, often through gaps, cracks, or inadequately sealed areas in the building envelope. This is particularly relevant in maintaining energy efficiency and indoor comfort, as significant heat loss through exfiltration can lead to higher heating costs and decreased comfort levels.

In contrast, infiltration involves the uncontrolled entry of outside air into a building, which can lead to heat gain in the summer or unintentional heat loss in the winter. Understanding these distinctions helps in evaluating and improving a building's energy performance and overall thermal integrity. Other terms, such as ventilation and thermal bypass, pertain to different aspects of air movement and building performance, underscoring the importance of precise terminology in this field.