Did you know that heat transfer through windows can account for up to 25 percent of your energy bill by allowing heat out during the winter, and makes your air conditioner work overtime to combat the sun’s warming? Drafts and leaks can be the biggest culprit of energy waste but can also be fixed with relatively little effort.
A simple way to check for a draft is to close all windows and doors, then run a candle or burn incense along the frame while watching the smoke to see if it gets pulled in or out. This works best on a windy day — and preferably with a fan set up to blow air out of your house. This simulates one of the tests an energy auditor would do when checking the energy efficiency of your home. Additionally, if you can close a window on a sheet of paper and pull it out without tearing it, then there is definitely a problem.
Take note on which windows are drafty and need to be fixed and which ones need to be replaced completely.