Yes I am willing to pay for heat. The main concern is finding a GH that doesn't leak air (or collapse in wind and snow).

I posted, but it got all wacky. I apologize if this is a repeat.

I have a Growing Spaces Dome. I live in Colorado at 6000 ft. We have snow and wind.

I do heat in the Winter. I could grow cool weather crops without heat, but I winter over a lot of tropicals in there. I use a small heater on a thermostat set to 40. This is not warm enough to grow warm crops. My heating bill is not outrageous.

They aren't cheap, but worth every penny.

Thanks for that. Seems I researched a few years ago and decided too expensive for me but they are an incredible system! Will look up again.

fireweed-

What area of the country are you in, how cold does it get in winter, how much snow loading do you get, how big of a greenhouse do you want, and what temperature would you like to maintain?

Well it's zone 5, but we get quite a bit of snow. Preferably 12' x 20+' but I'm thinking it will have to be smaller for budgetwise.

Just above freezing works for me!

From what I've seen the hobby greenhouse kits are too expensive for what you get. Try looking at the commercial greenhouse kits. Buy a strong frame built for your snow load conditions. Then if necessary save on the covering material. Double layer inflated poly is much cheaper than 2-3 layer polycarbonate. The bigger the greenhouse the lower the cost per sq ft. Maybe something like this 14x28ft for $5700: http://www.farmtek.com/farm/supplies/prod1;ft_greenhouses-ft_commercial_greenhouse_kits-ft_solarstar_greenhouse;pg104840s_104843S.html

I'm using double layer, inflated, woven poly. http://www.robertmarvel.com/Greenhousecover.html I like it a lot. Cheaper still would be double layer inflated 6 mil greenhouse poly.

That said if I could afford it I'd use double layer polycarbonate or similar. But I'm 75 and covering my 16ft tall greenhouse is for younger men. Covering a 14x28x9ft tall greenhouse with any poly would be easy even for me, by myself if necessary.

Thanks fruit nut, I've put in a call to a commercial GH builder and we will be talking today. Double inflated poly may be the trick. I didn't want to be bound to electricity for the fan but I may need to suck it up for an affordable greenhouse.

I would prefer to buy a polycarbonate kit, but everything I can find online are either super expensive or don't look of quality. Wish I could see them into person before ordering!

fireweed-

Do you have a backup generator in case you lose power?