28X32, insulated heavily including a garage door with insulated panels and double pane windows, radiant tubing in the floor, and heat the liquid with a 2nd hot water heater installed in the basement of the house. No open flame in the shop. I built the shop, so was able to heat it the way I wanted. I think it costs less than $25 a month to heat. Bonus: I found a nice 220 volt window air conditioner so cut a hole in one of the walls and chill the place down when the Kansas heat gets crazy.