To achieve 4 air changes per hour in a space sized 100' long x 75' wide x 9' high, how many CFM is required?

To determine the required CFM (cubic feet per minute) to achieve four air changes per hour in a space measuring 100 feet long, 75 feet wide, and 9 feet high, you first need to calculate the volume of the space.

The volume can be calculated using the formula for the volume of a rectangular space: length × width × height. In this case, the volume would be:

100 feet × 75 feet × 9 feet = 67,500 cubic feet.

Next, to find the total volume of air that needs to be exchanged to achieve four air changes per hour, you multiply the volume of the space by the number of air changes:

67,500 cubic feet × 4 air changes = 270,000 cubic feet per hour.

Since CFM is a measure of air flow in terms of cubic feet per minute, you need to convert the volume per hour to volume per minute by dividing by 60 (the number of minutes in an hour):

270,000 cubic feet per hour ÷ 60 minutes = 4,500 CFM.

This calculation shows that to achieve four air changes per hour in the specified space, a flow rate of 4,500 CFM is necessary. Therefore