What moisture-related issue can arise from mechanical ventilation using outside air?

When mechanical ventilation uses outside air, it brings in not only fresh air but also any moisture present in that air. If the incoming air is humid, it can contribute to higher levels of moisture inside the building. This increased humidity can create a conducive environment for mold growth, which thrives in damp conditions. Mold can lead to significant indoor air quality issues and affect both health and structural integrity.

While condensation in the ducts, increased humidity levels, and pest attraction are possible secondary effects of improper ventilation or inadequate moisture control, the primary concern fundamentally ties back to moisture and mold problems. Ensuring that the mechanical ventilation system is designed and operated to manage moisture effectively is crucial to mitigating these risks.