About the number of air changes in the house: the number of times to change the total air in a space in an hour is called the number of air changes, and the unit is: times/hour. Calculation of air exchange times: air exchange times = design air volume/total indoor net air volume (net area × net height).
According to the international standard ASHRAE 62- 1989, the minimum number of fresh air changes per hour should be greater than 0.35 times and not less than 25m3 per person.