What type of pressure does an exhaust-only mechanical ventilation system create within a home?

In an exhaust-only mechanical ventilation system, the primary function is to remove air from the interior of the home in order to improve indoor air quality. This process creates a difference in pressure because as the exhaust fan pulls air out, it decreases the amount of air inside the home. This reduction in indoor air volume results in a negative pressure relative to the outdoor environment.

When the air is exhausted from the home, it creates a vacuum effect that can lead to air being drawn in from outside through any existing leaks or openings in the building envelope. This is particularly important as it can enhance air circulation and help with ventilation, but it may also lead to unwanted drafts and infiltration from unconditioned spaces.

This understanding of pressure dynamics in a home environment is crucial for maintaining proper ventilation and ensuring that air quality standards are met while also considering potential energy losses.