air changes per hour formula?

best answer
This is the formula for ACH (air changes per hour) ACH = CFM x 60 / (Area x Height) where ‘Area’ is the area of the space where you intend to have an HVAC device and ‘Height’ is the height of the ceiling. The formula is basically ‘how many cubic feet of air can an HVAC unit provide every hour’ divided by the volume of the room.