Your Garage is Important, Too!
The garage is probably one of the last places people think to make improvements to or make energy efficient. What many people don't realize is the garage (especially if it is attached to the home) can be one of the largest culprits of air loss in your home.
One of the easiest ways to help prevent this loss is to add weather stripping to the bottom of the garage door and the door leading from the garage into your home. This prevents the outside air from coming in and the air conditioned air from escaping - and as a bonus - it acts as a cushion for the garage door, which cuts down on noise when closed. If you feel a breeze on the sides of the garage door, this is a clue you need to add weather stripping tape to seal the leaks.
Referenced from: BounceEnergy.com