TABLE 6:  Heating, Venting and Cooling Calculations     Comments
VENTILATION:  
Greenhouse Volume Calculation: Width (11.25') x Length (16') x Average Height (8')  
= 1440 Cubic Feet 16" Fan rated for 2240 CFM
Multiply volume by 0.75 for your fan CFM (Cubic feet per minute) Note: Sundance doesn’t use this factor.
= 1080 Cubic Feet (recommended fan size)  
  16" GP rated for 2240 CPM (Cubic feet per minute)  
Shutter size:  Divide fan size by 250 then by 2 shutters for square feet of shutters.  
= 2.16 Square feet.  Multiply by 144 sq. in. per sq. ft. and take the square root: (2) 20" Shutters with hoods
= 17.64 inches --> round up to (2) 20" shutters. Option (motorized closure for cold weather
             areas)
HEATING See http://www.h2othouse.com/html/GreenhouseTemp.html for an article on Greenhouse Temperatures.  
Total wall and roof surface area = 2 x (16'x8'roof + 5'x16'sides + 11'x8'ends)  
A = 592 square feet  
Temperature difference between coldest outdoor winter temperature and night  
  temperatue desired in greenhouse  
D = 50 degrees -7 degrees = 43  
Formular to calculate Btu's = A x D x 1.1 - 30% if using twin wall and - 30% if attached.  
Btu's = 20057 Btu's assuming twin wall. Vented recommend for growing Orchids.
    Recommend "Southern Gas Burner" Model # C-1(non-vented).  Available from Sundance supply.  The Model A-1 is vented and rated for 25,000 BTU.       Note:  This heater (Model C-1) is rated for 25,000 BTU's which will allow you to keep the greenhouse at 50 degrees with an outdoor temp. of 8 deg.
MISTING  
For cooling and humidity control.  One 2 or 3 gph nozzle for every 12 to 14 sq. feet.  
  # Nozzles = 11.25 feet x 16 feet / 14 sq.ft per nozzle =  
# Nozzles= 13 nozzles  
  or one Hydrofogger rated for 250 sq. ft.        
Framing  $   384.36
Foundation  $   428.50
Glazing/Trim  $2,343.00
Heating, Venting, Shading, Misting  $1,440.52
Electrical  $   349.00
Piping  $     28.00
Total  $4,973.38