Greenhouse heating cost?

[orion141]

Hi all,

So I have been toying around with the idea of a 8x10 green house (potentially the turner brightleaf 8x10 with twin wall polycarbonate) in my back yard. This would be a freestanding structure (not lean to). I live in Connecticut (south central ct in zone 7) and am concerned about heating costs. We have propane as our heating source for our hone and I was wondering if anyone could even ballpark potential heating costs for this type of greenhouse in my location (using a propane heater). I could bubble wrap in the winter, but would not be able to dig 3-4 feet into the ground for the base. Thanks in advance.

Orion