How to calculate the ventilation requirments of a greenhouse.

MEMBER

FIGURING VENTILATION

(use this for ventilation only, cooling formula included below also)

1 AIR CHANGE PER MINUTE OF EXHAUST: STILL WILL GET 4-5 DEGREES TEMPERATURE RISE IN A SMALL GREENHOUSE AND 10 DEGREES IN A LARGER GREENHOUSE WITH THIS FIGURE.

1.) Width x Length x HEIGHT TO EAVE = O

2.) HEIGHT TO RIDGE - HEIGHT TO EAVE = M

3.) M x Width x Length = P
2

4. P + O = CUBIC FEET PER MINUTE

example: 10’ x 10’ greenhouse
1.) 10 x 10 x 6.6 = 660
2.)10’ 4” - 6’ 6” = 3.8
3.) 3.8 X 10 X 10 = 190
2
4.) 190 + 660 = 850 CFM REQUIRED

For Cooling (evap. coolers)

Freestanding Greenhouse: Width (10’) x Length (12’) = 120 Sq. Ft.

Multiply 120 x 15 CFM = 1800 CFM required

Lean-to Greenhouses: Multiply width (6’) x length (10’) = 60 sq. ft.

Multiply height of back wall (9’) x length (10’) = 90 sq. ft. and divide by 2 (90/2) = 45 Sq. ft.

Add 60 Sq. ft and 45 Sq. ft. = 105 Sq. ft

Multiply 105 Sq. ft x 12 CFM = 1260 CFM required

FIGURING VENTILATION

(use this for ventilation only, cooling formula included below also)

1 AIR CHANGE PER MINUTE OF EXHAUST: STILL WILL GET 4-5 DEGREES TEMPERATURE RISE IN A SMALL GREENHOUSE AND 10 DEGREES IN A LARGER GREENHOUSE WITH THIS FIGURE.

1.) Width x Length x HEIGHT TO EAVE = O

2.) HEIGHT TO RIDGE - HEIGHT TO EAVE = M

3.) M x Width x Length = P

4. P + O = CUBIC FEET PER MINUTE

example: 10’ x 10’ greenhouse

1.) 10 x 10 x 6.6 = 660

2.)10’ 4” - 6’ 6” = 3.8

3.) 3.8 X 10 X 10 = 190

4. 190 + 660 = 850 CFM REQUIRED