With a couple of notable exceptions over the past few years, we don't get much if any snow and ice here in Austin during a typical winter.
When my wife and I built this house we had the HVAC system extended to include the garage; the space is insulated, and it is double sheetrocked from the main house. A friend of mine and I built a thermally and acoustically insulated wall to seal the opening outside the garage door. Years later when it was time to get the HVAC replaced, we replaced the single system with two smaller ones - one for the man cave and one for the rest of the house - so that during the winter I can run the AC in the man cave and the heat in the rest of the house at the same time.