Green Newton

Air leaks are a large source of heat loss in the home during winter. A common place where air leaks occur is under the door leading from the house to the garage because they are often not as well sealed as doors leading directly to the outside. Install a door sweep to seal the gap between the bottom of your door and the threshold to prevent cold air from coming in and warm air from escaping from your home. Stopping this air flow will keep heated indoor living space more comfortable and prevent increased energy bills.

https://www.energystar.gov/products/energy_star_home_tips