What is the leakage of outdoor air into a building through cracks and openings called?

The correct choice identifies the infiltration of outdoor air as the process in which air enters a building through unintentional openings, such as cracks, gaps, or poorly sealed areas. Infiltration plays a significant role in the overall air quality and energy efficiency of a building. It introduces outdoor air, which can affect indoor temperature, humidity levels, and the operation of heating and cooling systems.

Understanding infiltration is crucial for power engineers and building managers, as it relates to energy loss and the effectiveness of HVAC systems. When outdoor air infiltrates a building, it may require additional energy to heat or cool the interior spaces, impacting operating costs and system performance.

The other terms refer to different processes. Ventilation typically describes the intentional introduction of outdoor air to improve indoor air quality, often managed through mechanical or natural systems. Diffusion is a broader term often used in physical sciences to describe the spread of particles from high to low concentration but does not specifically address air movement into buildings. Exfiltration refers to the movement of indoor air to the outside, often occurring when indoor air escapes through openings. This distinction is important in understanding air flow dynamics within buildings for effective engineering and energy management.