Why does heat escape from your home in the first place? To understand that, it helps to know a little bit about the science of heat. As you probably know, heat travels in three different ways by processes called conduction, convection, and radiation. (If you're not sure of the difference, take a look at our main article on heat for a quick recap.) Knowing about these three types of heat flow, it's easy to see lots of ways in which your cozy warm home is leaking heat to the freezing cold world all around it:
Well-insulated homes that hold onto their heat in winter tend to be better at keeping the heat out in summer, so any improvements you make to your insulation should also help to keep your air conditioning bills down.