Excellent and low-cost energy efficiency tip to keep a little more heat out from the garage. Using simple insulating material can be applied to the panels on the garage door. Additionally, window film can be applied to the windows to reject some more heat while still letting the natural sunlight in.
The only objection to the article is that it recommends purchasing window film from Lowes. Lowes sells Gila brand film with is like the bastard step-child of prefessional grade film company called Llumar. Professionals don’t use Gila film, and you should not either.
Look for pre-cut window tint companies like SnapTint.com, which is one of our advertising partners, that sells professional grade window film custom cut to the sizes you need.