Air leakage entering a building is called what?

Air leakage entering a building is called what?

• A. Infiltration
• B. Exfiltration
• C. Ventilation
• D. Filtration

Answer: (A)

Air entering a building through cracks and gaps is called infiltration. It happens unintentionally when pressure differences—caused by wind, temperature differences (stack effect), or the building’s HVAC operation—push outside air inside. Infiltration affects energy use since that outside air must be conditioned, and it can influence indoor air quality. The opposite process is exfiltration, where indoor air leaks out. Ventilation is the intentional exchange of indoor air with outside air to control air quality, usually through designed systems or openings. Filtration is the removal of particles from the air by filters, not the movement of air itself.

Air entering a building through cracks and gaps is called infiltration. It happens unintentionally when pressure differences—caused by wind, temperature differences (stack effect), or the building’s HVAC operation—push outside air inside. Infiltration affects energy use since that outside air must be conditioned, and it can influence indoor air quality. The opposite process is exfiltration, where indoor air leaks out. Ventilation is the intentional exchange of indoor air with outside air to control air quality, usually through designed systems or openings. Filtration is the removal of particles from the air by filters, not the movement of air itself.