[tomwoodworker]

As of two years ago, the design team had only standard 'packages' to offer. I think the wisest thing I did was to ask for Carrier's highest SEER rated condenser. At the time it was 20. Secondly, go with the best insulation package they offer.

But, I would not recommend upgraded garage doors as that is something you can do once you take ownership of your home. (This is just my opinion.) And, yes by all means ask for the garage to be insulated as well. I had a mini split installed once I took ownership of my home and it seems worthwhile if you're going to spend anytime in it.

Just a word about warm air rising. This is correct but the other issue is heat. Heat will always seek a cooler space to migrate to. So if your garage attic is 115 degrees
(not likely to be much higher) it will seek to come downward into your garage. What stops it, or retards it, is the amount of insulation that can provide a barrier to the transfer.