My shop is about 24' x 24' (enclosed) plus a 12' wide carport on one end. The building is completely open on the inside with a 6/12 pitch roof. To heat and cool this large volume (length x with x height), I had a 4 ton Trane heat pump installed as a split unit. The compressor is outside under the carport while the blower unit is mounted in the storage area over the carport. It will easily keep the shop area either cool or warm and under normal use only costs about $20 - $30 per month for power. I also have two large ceiling fans that hang from 6 foot rods. During much of the year, just using the ceiling fans will move enough air to keep things comfortable. Before installing the heat pump, I tried heating the shop with a couple of space heaters. That kept things bearable but not comfortable. The walls and ceiling are insulated, but the main overhead door is not.
