OMG... we are dreading the next utility bill. We better have a real green house by next season!
Where I live, a real greenhouse is even _more_ expensive!
I have a friend who, in her youth, grew seedlings for sale. She started out with a wood-heated greenhouse. A few days ago, she told me that it was like having newborns: she never slept more than a couple of hours at a time in March and April. Eventually, she graduated to propane and the last year she had the greenhouses (2 of them), the bill for heat was shocking. I think that was 4 years ago. Today, it would be another 50% higher.