I have a two and a half ton heat pump with LPG gas backup downstairs in my shop which is about 33x44. Works out great. Think I've only ever used the air conditioning 5 or 6 times and all the years that I've had that shop built. It's shaded by trees and I usually just run the ceiling fans and it stays around 12° cooler inside the shop than it is outside in the heat of the summer. In the winter time I put the thermostat for the heat pump and or LPG gas at around 65 or 68° if I'm down there working. When I go out of the shop I turn it down to 50°. Been great for many years