General con sen cese is that insulating the door really does or does not help?? If not,, don't want to spend the $$. I lived in a town home ass o cee e asition. Can't punch holed in the walls. Garage with a spot cooler would need duct to exhaust. That garage door is hot. Like I mentioned before, I have been in the commercial and industrial HVAC and insulation business for 30 years. Normally I would slap anchor pins, glued, and fiberglass with foil backing, but costly. Cut, cut, cut. Expensive. Other materials would be cheaper and just as effective.
Now for you inventive people, Bob, my commercial favorites is insertions of dehumidified and colled off outside air. That is pressurizing the building or rooms with outside air humidity taken out in the same affect of a dehumidifier. Cool the air with a freon coil and reheat if need be. The positive air keeps air incertion from doors and winders. Great for older homees. The last town home we had built 5 years ago was a 5 star energy efficient home. The whole building was pressurizes 5 times for leaks and repaired. 3 pained windows, 2 pained sliders massive amounts of insulation solid out side doors, and balancing grills. Really done right. In one main bathroom up stairs. Houe is 4,200 SF, 4 bed rooms 3 1/2 bath with a very large build out up stairs. Figuring out how to insert outside air to pressurize the building with out knocking a whole in the wall to bring in outside air. Well, Bob, just so happens that one full bath up stairs has a dehumidifier built into the exhaust fan. Oversiszed which works off ot a sensor that turns on to exhaust when it hits a point you preset. It so happens to sit next to the AHU room. So to bring in outside air, Bob, reverse the fan to bring in the out side air, duct it into the return duct of the AHU with a UV light set up charcoal for smells, and dehumidify thru the AHU. Wa, la no more holes, fan already there, duct work there. 50 units in this gated community and could sell it to 49. Sorry long winded and other than installing a chiller,, this would be it.