Supply ventilation mechanically introduces filtered outside air into conditioned spaces while relying on natural exfiltration through building leakage. This system pressurizes the indoor environment, improving comfort and filtering outdoor contaminants. Supply ventilation is particularly effective in clean, dry climates where humidity control is less critical.
Technical Details
Supply systems typically include intake dampers, filters rated MERV 8 or higher, and distribution ductwork sized to deliver 0.35 air changes per hour (ACH) minimum per ASHRAE 62.2. Air volumes range from 50 CFM for small homes to 200+ CFM for larger residences. Properly sealed ductwork and strategic placement of supply registers ensures even distribution throughout occupied zones.
Practical Significance
Supply ventilation maintains positive indoor pressure, reducing infiltration of unconditioned outdoor air and improving energy efficiency compared to exhaust-only systems. However, without controlled exhaust pathways, stale air accumulates in unused spaces. This method works best paired with operable windows or dedicated exhaust fans. In humid climates, supply ventilation can increase indoor moisture levels, potentially causing condensation and mold issues without proper humidity management.