Ventilation is very important in an energy-efficient home. Air sealing techniques can reduce air leakage to the point that contaminants with known health effects such as formaldehyde, volatile organic compounds, and radon are sealed into the house. Ventilation also helps control moisture, which can lead to mold growth and structural damage.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has determined that a home's living area should be:

• Ventilated at a CFM rate determined by adding 3% of the conditioned space floor area to 7.5 times the number of bedrooms plus one [formula: vent CFM = 0.03A + 7.5 (# bedrooms + 1)] as published by ASHRAE 62.2 in 2013.
• In a tight home, mechanical ventilation is necessary to achieve this ventilation rate.
• ASHRAE Standards are revised every three years.