How is infiltration defined?

Infiltration is defined as the process by which outdoor air enters a building through unintentional openings and gaps, with the implication that this flow is typically balanced by an equal outflow of indoor air. This phenomenon plays a significant role in the overall ventilation dynamics of a building, influencing indoor air quality and energy efficiency.

Understanding infiltration is crucial for evaluating the performance of HVAC systems and overall energy consumption in a building. It highlights the necessity of managing air leakage to optimize energy use, as uncontrolled infiltration can lead to increased heating and cooling costs and may also affect the comfort levels within the indoor environment. The process is distinct from controlled ventilation, where the goal is to purposefully introduce air through designed systems, like exhaust fans or ventilation ducts.

This concept directly contrasts with the other options: indoor air circulation refers more to the movement of air within the home without the element of outside air; heat transfer addresses thermal dynamics rather than airflow; and the reaction of air with pollutants pertains to air quality issues rather than the physical movement of air in and out of the structure. Therefore, the definition that encompasses the balanced inflow and outflow of air is essential to understanding infiltration.