[RedDutchessFarm]

The formula for calculating btu’s needed to heat a greenhouse is:

Total number of square feet of exterior of greenhouse(roof, sidewalls, endwalls)

Multiplied by:

the number of degrees you want to maintain between outside temperature and inside temperature

Multiplied by: 1.14 for single layer plastic. -or- .73 for double layer inflated plastic

Example:

2500 square feet of exterior area X 60 degrees (if it’s 0 outside you can keep it 60 inside) X 1.14 for single layer plastic equals:

171,000 btu’s

X .73 for double layer inflated equals:

109,500 btu’s

A huge difference between single layer and double layer inflated!