Luminita, It seems like you might want to research this more since your heating requirements are so extreme (unless you're independently wealthy). For instance, you might want to look up the guy who grows oranges in Nebraska with solar heating. And you might want to check out other zoning classes that permit agriculture before you decide where to move. Some do not tax high tunnel type greenhouses. Also, check out high efficiency gas heaters that recapture the latent heat of the water vapor. They generally don't have a chimney but use schedule 40 plastic drain pipe instead. The ones that vent directly into the greenhouse can raise the humidity too much but a lot of people use them. A lot depends on what you are willing to compromise on. For instance, most commercial growers orient their houses with the gables North South for even illumination but you might consider an East West orientation wooden A-frame with the North wall opaque and insulated. This would cut your heating in half with very little change in winter illumination. Also, using the inflation technique used on double wall plastic houses and adding a third layer on the inside with battens, you would get an R-2.5 insulation value on the south side. If you don't want to compromise design, you could save half your heating costs with a simple layer of white or reflective plastic pulled over the plants at night to reduce the radiant heat loss which I assume is extreme in your area due to clear nights. Radiant heat loss is the reason you can get a killing frost outside when the ambient temperature is 40F. Good Luck Tim _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net>