This thread from last week has a lot of info.
Suggestions for a cooler garage.
Remember, without A/C in the garage, it will never be cooler than the outside air. In my opinion insulating the door, which I did myself, helps when the door is down, but only if the sun is shining on the door. Since our Laundry is in the garage and I go in and out a lot, the screen made the most sense. Especially the horizontal slider where I only open a 3' section to exit and enter. The screen has the extra benefits of keeping bugs, snakes, lizards and alligators out of your garage.