How much are your leaky worn out windows really costing you? The vast majority of heat during the winter is lost through windows and doors? These are the two parts of your home that are most exposed to the elements and for every draft that you have coming through your windows, the colder it gets, the more it is going to cost you to heat your home. The same holds true during the summer. If you tend to run your air conditioning system a lot on the hot dog days of summer during July and August, you could be spending a lot more on your utility bills than you should, all because of the condition of your windows.