I have been following this thread with interest, because I am also trying to cool my workshop, and provide winter heat. But just ventilation won't do the job; here in NC humidity is as big a problem as the heat. If I bring in outside air, I just bring in moisture. I put in a window AC/heat unit,
11000 BTU, and can get a nice, comfortable temperature. Now I would like to add insulation to cut operating cost, but it looks like it will cost over $500 for insulation, which will then need to be installed just below the roof on stringers that are 11' high. The fiberglass insulation that comes 24" wide is R-30. Does it make sense to put that much insulation in a space with two garage doors and nothing in the walls?Steve