When it comes to keeping your home warm in the winter and cool in the summer, increasing your home’s insulation should be a top priority. Insulating your home’s walls and ceilings and using caulk and weather stripping to plug air leaks near doors and windows saves 20 to 30 percent on your home’s heating and air conditioning bills.

Read more at http://articles.businessinsider.com/2012-02-23/news/31089926_1_conditioning-heating-plug-air-leaks