I have one similar to the ones in the link Jerry provided. I have had it in for a number of years. Mine is 10w x 12 hi. It is "insulated" with a piece of bubble wrap type insulation. I think it is R4 value or something lame like that. Better than nothing but, not the best. I heat with a wood stove so,. I don't worry about losing some heat there. The shop is barn shaped and gas R19 in the walls and R30 in the ceiling so, it is pretty well insulated other than the door. I am more than comfortable out there in the winter but, we rarely drop much below the upper 20s. Most of the winter is closer to upper 30s lower 40s overnight so, probably a bit warmer than your winter!
