What causes infiltration losses in a building?

Infiltration losses in a building primarily occur due to cold outside air being drawn into the building. This phenomenon happens when there are cracks, gaps, or openings in the building's envelope, such as around windows, doors, or other structural weaknesses. The movement of cold air into the building compromises energy efficiency and increases heating demands, as the heating system must work harder to maintain a comfortable indoor temperature. This infiltration not only leads to increased energy costs but can also result in comfort issues for occupants.

While hot air escaping through vents can contribute to energy loss, it typically falls under the category of ventilation losses rather than infiltration losses. Damaged insulation affects the building's ability to retain heat but does not directly involve the movement of outside air. Similarly, high humidity levels inside can impact comfort and energy use but are not a direct cause of infiltration losses in terms of air exchange with the outside environment.