What surprised me after I built my garage is that in the summer time it would be probably ten degrees hotter in the garage than outside. Maybe more. I know that 95 degrees outside felt cool compared to inside the garage. After years of being miserable when working in my garage in the summer time, and not being able to work for more than an hour at a time and then spending two hours in the house cooling off, I bought a 28,000 BTU window unit A/C for the garage. Stick building, 1700 square feet. Roof is only half insulated, I did insulate the garage doors, walls are not insulated at all. As long as I turn the A/C on before noon, it will get the garage cool and keep it cool. If I wait till 3pm, not so much. Turn it off in the evening. Will still be cool the next morning. I have been amazed at how well it has worked. Honestly don't know how I ever got along without it. If I run it every day, adds $100/month to my electric bill. Worth it to me.