Ventilation Rate Calculator

How It Works

ASHRAE Standard 62.2 sets minimum ventilation rates for residential buildings to maintain healthy indoor air quality. The formula accounts for both floor area (pollutants from building materials, furnishings, and cleaning) and occupants (CO2, moisture, and odors). Modern tight homes may not get enough fresh air through natural infiltration, leading to stale air, high CO2, excess moisture, and accumulated VOCs. Mechanical ventilation solves this. Exhaust-only systems (like bath fans) are cheapest but create negative pressure. Balanced systems (HRV or ERV) are best because they exchange stale indoor air for fresh outdoor air while recovering 70 to 85 percent of the energy from the outgoing air. HRVs are better for cold, dry climates; ERVs are better for humid climates because they also transfer moisture.