When Determining Heating and Cooling Requirements for Your Greenhouse, the First Step is figuring your Volume and Surface Area of the Structure.
Step One: What type of Structure do you have: For Example: quonset, single ridge, gutter connected. (Gutter Connected is figured by taking one of the houses and determining the Volume or Surface Area [each section must be figured like an individual house] and then multiplying by the number of total houses.
Step Two: Assume pitch of Single-Ridge is 26.5 degrees. Other parts of the formula are B=W/2: G=W/4: RB=B+(B/12) and L stands for length and W stands for width and H stands for height.
Step Three: Determining the Surface Area of Your Greenhouse
Formula for Surface Area of Single Ridge Greenhouse: 2(L x H) + 2(W x H) + 2(L x RB) + (G x W) = Surface Area or S.A.
The S.A. Formula for Quonset Style Houses: is different from Single Ridge, which is given below.
2(W x H) + 2(L x H) + 2([3.142 x G x B] / 2) + L(3.142 x [(Square Root of G Squared + B Squared) / 2] = S.A. ft cubed (This formula has more variables, square roots, and math, SO BE CAREFUL WITH THE CALCULATIONS)
Here are Some Examples: Single Ridge Example: Length = 100 ft. Width = 20 ft. Height = 25 ft.
[ B = W/2 so B = 20 / 2 or 10 ] [ G = W/4 so G = 20 / 4 or 5 ] [ RB = B + B/12 so 10 + 10/12 or 10.833]
2(100 x 25) + 2(20 x 25) + 2(100 x 10.833) + (5 x 25) = 8,291.6 feet squared
From the Example Above if your greenhouse was gutter connected and it looked like the picture below you would multiply the total by three giving you a Surface Area of 24,874.8 ft.
Here is an example on how to Figure Surface Area for a Quonset Style Greenhouse: Length = 120 ft. Width = 65 ft. Height = 20 ft.
[ B= W/2 so B = 32.5] [ G = W/4 16.25]
2(65 x 20) + 2(120 x 20) + 2([3.142 x 16.25 x 32.5] /2) + 120(3.142 x [ (Square Root of 16.25 squared + 32.5 squared) /2]) = 15,712.05 feet squared
For Practice Try This Problem: ( Single Ridge Style ) Length = 125 ft. Width = 35 ft. Height = 15 ft. { Answer is 9,846.25 feet squared}
Step Four: Determining the Volume of Your Greenhouse
Equation for Single Ridge: L( [ W x H ] + [ ( W x G ) /2] ) = Volume
Here is an Example: Length = 75 ft. Width = 31 ft. Height = 19 ft.
75 ( [ 31 x 19 ] + [ ( 31 x 7.75 ) /2 ] ) = 53,184. 375 feet cubed
Equation for Quonset Style: ( H x W x L) + L [ (3.142 x G x B) /2 ]
Here is an Example: Length = 95 ft. Width = 27 feet Height = 24 feet
( 24 x 27 x 95 ) + 95 [ (3.142 x 6.75 x 13.5 ) / 2 ] = 75,159. 95 feet cubed
For Practice Try This Problem: ( Quonset Style ) Length = 97 ft. Width = 42 ft. Height = 25 ft { Answer is 153,356. 8 feet cubed }
