| Length of Greenhouse - in feet|
| Width of Greenhouse - in feet|
| Height of Greenhouse - in feet |
| Fan CFM Needed - This is the optimal exhaust fan CFM (Cubic Feet per Minute) rating for your greenhouse. A fan this size will exchange the air in your greenhouse one rate per minute which is the recommended ventilation for most small greenhouses.|
Exhaust fans require 18 inches (324 sq. in) of air intake area per 1000 CFM to function properly.