In a building, when air pressure inside is lower than outside, which phenomenon occurs?

In a building, when air pressure inside is lower than outside, which phenomenon occurs?

• A. Air pushes into the house (Infiltration)
• B. Air pushes out of the house (Exfiltration)
• C. Air circulates within walls
• D. No air movement

Answer: (A)

Air moves from higher pressure to lower pressure. When the inside of a building is at lower pressure than the outdoors, outside air is pushed into the building through cracks and openings. This inward flow is called infiltration. It’s unplanned air leakage across the building envelope and can affect energy efficiency and comfort. The opposite situation, where interior air is pushed outward, is exfiltration.

Air moves from higher pressure to lower pressure. When the inside of a building is at lower pressure than the outdoors, outside air is pushed into the building through cracks and openings. This inward flow is called infiltration. It’s unplanned air leakage across the building envelope and can affect energy efficiency and comfort. The opposite situation, where interior air is pushed outward, is exfiltration.