Powered roof fans can inadvertently suck which of the following through leakage pathways?

Powered roof fans are designed to enhance ventilation in attics by expelling warm air outside. However, when these fans operate, they create a negative pressure within the attic space. This negative pressure can inadvertently draw air into the attic through any available leakage pathways, which may unintentionally include conditioned air that was previously cooled or heated and circulated through the living space.

When conditioned air is pulled from the interior of the home, it can lead to several issues, such as increased energy consumption—since the HVAC system must work harder to replace the lost air—and decreased indoor comfort levels. In contrast, outdoor air, filtered air from the attic, and exhaust fumes are less likely to be drawn into the living space in significant quantities during normal powered fan operation compared to conditioned interior air, which is also a direct consequence of the negative pressure created by the fan. Thus, the focus on the dynamics of airflow within the home clearly supports that the conditioned air from the interior is the most susceptible to being inadvertently sucked through leakage pathways when powered roof fans are in use.