How might mechanical ventilation impact a building’s infiltration/exfiltration?

Mechanical ventilation can significantly impact a building's infiltration and exfiltration dynamics by creating a depressurization effect within the home. When mechanical systems introduce air into a space systematically, they can lead to a drop in internal air pressure relative to the outside atmosphere. This depressurization causes outside air to flow in through unintentional openings, such as cracks, gaps, or other sources of infiltration.

In this context, depressurization is particularly critical because it alters the movement of air in and out of the building. It can enhance the natural ventilation that occurs due to pressure differences, allowing outdoor air to enter the home even when windows and doors are closed. This influx of air can bring in unwanted pollutants, allergens, and moisture if not properly managed, which might influence indoor air quality.

By understanding the relationship between mechanical ventilation and air pressure in a building, one can appreciate how manipulation of these factors is essential in achieving a balance for optimal indoor environmental quality and energy efficiency.