Final answer:
The majority of heat loss in a house is typically through the windows, as they are a major region of heat transfer to the outside. Insulating the attic is also an effective method to reduce heat loss and, consequently, heating costs.
Step-by-step explanation:
The majority of the heat loss in a house on average is through the windows. A thermograph of part of a building shows that windows are indeed a significant area where heat transfer to the outside is most severe. During the heating season, much of the heat that leaves the house does so through windows, especially if they are not well insulated or if they are single-paned. Improving window insulation with double paning or adding treatments like curtains or blinds can help reduce this heat loss.
Additional strategies for reducing heat loss include adding insulation to the attic, as it is an effective way to retain heat. In fact, an example calculation shows that adding an extra 8.0 cm of fiberglass insulation in the attic could significantly reduce heating costs, ignoring air infiltration and heat loss through windows and doors.