Building an Energy Efficient Home for Less, Tip 3

February 11, 2008

No Windows and Doors on the North Wall.

The north wall is the coldest wall on the house and since both windows and doors typically have the low R values, installing them on a north wall makes absolutely no sense from an energy efficiency point of view.

The north wall is the coldest wall on the house for a couple of reasons. From the Autumnal equinox on September 21 to the Vernal equinox on March 21, the sun is always in the southern sky and therefore the north wall never receives direct sunlight and is in perpetual shade for these 6 months. The low insulation values of doors and windows on this side allow copious amounts of heat to leave without receiving any solar gain in return. In fact homeowners can receive the biggest bang for their insulation dollar by adding some to the north-facing wall.

Compounding the lack of sunlight on the north-facing wall is the cooling effect of the northwest winds. Windows and doors are notorious for letting in drafts because due the process of linear expansion. What this two-bit phrase means, is that materials expand when it is hot and contract when it is cold. Since both windows and doors are each made of several different materials that expand and contract at different rates, it means that when the temperature changes, gaps are created between the materials and these gaps let in the cold outside air.