Repair the gaps around doors and windows

More than 20 percent of the air that enters and exits your home does so around your windows and doors. To keep your heated (or cooled) air inside where it belongs, get some caulk and weather stripping and get to work. Sealing your windows and doors will help reduce your energy consumption and save money. It can also help delay replacing your windows and doors, which can cost thousands.

--Kudzu website