I haven't figured out permanent heating for my art studio - still using two oil-filled radiators. I have foam insulation in the ceiling and insulation they make out of old blue jeans in the walls. But the thing that has worked great for cooling is a poultry fan at the peak. It's good and strong and really keeps it pretty comfortable. It took me a while to find the fan, but I've been really happy with it. You can see the fan over the door in this picture.
The building is one of those Amish storage sheds and we added electric, more doors, windows, etc. Still don't have a good floor - it's uninsulated plywood on 6x6s (or 4x4s) on a gravel bed. Moved two sewing machines in there today...uh oh.
[ATTACH=CONFIG]500145[/ATTACH]