I was just getting ready to buy one of these units 2 summers ago. Then I was discussing with Family at a Family get together and my Dad mentioned he had a couple of old window air conditioners out in the garage. So I took one of them and installed in my garage. Best damn thing I have ever done. I should have done that 25 years ago. It is amazing how nice it feels in the garage at 70-75 with no humidity when it's 95+ outside.

Just checked the electric bill for Jan. We had an average daily temp. of around 27 and it cost $94 to heat my 800 sf garage with a split mini. It had a 16' door that got opened twice a day. So 783 kw @ .12 a unit. This was set @ 60 and would keep the farthest end of garage @ 55. The garage would have stayed above 40 without any heat so If I was building a new garage and had access to natural gas I would use it for heating and not give it a second thought. For air they work great. Mike

Holy crap! Mine's 864 sq. ft. kept at 65* and I don't think it costs me that much for the whole winter - natural gas. But the bay doors are seldom opened.

And that's with 2 x 6 insulated walls. Adding another R-25 to attic now. The nice thing about a gas furnace is you can let it cool down at night and then turn it up in the morning and it will reach temp quickly. These can't catch up in cold weather for hours. My friend has his gas unit on a nest app and leaves it set to 55 and if he's going to be working just turns up the heat with his phone when he's drinking his coffee or on his way home and by the time he's ready the garage is nice and warm.