Heat Seeks Out Cold

Heat will travel from a warmer spot in your house to a cooler spot in your house.  In cold weather, it flows from the heated rooms to areas like your unheated attic or garage.  It even seeks to escape your house to the oudoors.  In hot weather, heat flows form outside your home to its interior.  To maintain comfort, the heat lost in the winter must be replaced by your heating system, and the heat gained in the summer time must be removed by your air conditioner.  Insulation that you may have resists the flow of heat, preventing unwanted circulation.  Thus, in a well insulated house, rooms stay warmer in winter, cooler in the summer, and cause less energy expenditure.