I did some research into how to build a grow room. See my annotations at http://bigbudsmag.com/math-skills-marijuana-grow-rooms-cannabis/#annotations:m3-4Ak6PEeat_6MDv0Opvg
Because the length and width of my grow room are both 25 feet and the height of my room is 10 feet, I need to find the cubic feet of this room, and the cubic feet of this room is 6250 cu. ft. Also, you need to find out the CFM or Cubic Feet per Minute. My research said that I have to clear the room in 5 minutes so the CFM is L x W x H / 5 minutes, which is 1250 Fan(s) CFM Required. I got my fan or blower on http://www.industrialfansdirect.com/blowers2pb/NFC-NHADP14H-3T.html.
“CFM stands for “cubic feet per minute” and is a measure of airflow, often used to describe the capabilities of heating, ventilation, and air conditioning systems. It describes the rate at which a certain volume of air moves in a certain period of time.” (http://whatiscfm.com/)
In the case of a blower or fan, it indicates how much air it can move each minute. So with my fan, a 1575 cfm fan can remove all of the air from my room that is 6250 cubic feet in 4 minutes (1575 cfm x 4 minutes = 6300 cubic feet of air).
Visit my grow room by clicking on these 10 slides.