Ventilation requirements are measured in cubic feet per minute (CFMs) of air. There are several ways to determine the right amount needed. Some rely strictly on the size of the home; others rely on the number of rooms.
The Room Count Calculation or the Air Change per Hour method shows you how to determine your ventilation needs.
The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) recommend a 0.35 air exchanges per hour for residential use.
Note: Always consult your local building code for minimum ventilation requirements.