What is infiltration in the context of building construction?

Infiltration in the context of building construction refers specifically to the process by which outside air enters a building, primarily through openings, cracks, or other unintentional spaces such as around windows and doors. This influx of air can impact indoor air quality, energy efficiency, and overall comfort within a building.

The correct choice highlights that infiltration commonly occurs around windows and doors, where seals may not be airtight, allowing outside air to mix with conditioned indoor air. Managing infiltration is crucial for maintaining energy efficiency in a building, as unintentional air leaks can lead to increased heating and cooling demands.

Other options describe different scenarios related to air movement or conditioning but do not accurately capture the definition of infiltration. For instance, air that leaks through insulation refers more to the loss of conditioned air rather than outside air coming in. Similarly, air that is conditioned in HVAC systems does not pertain to infiltration, as this involves air that has already been processed and is intended to maintain comfort inside the building.