Passive Solar (Home Energy Part 15)
Passive solar heating is a heating system with only one moving part: the sun. Passive solar design relies on ordinary visible light from low-angled winter sun, which penetrates south-facing windows during the heating season. Inside our homes, the sun’s visible light is absorbed by floors, walls, and other solid materials. Here it is converted to heat and warms our homes. 
For cool climates, installing the bulk of your windows on the south side of your home, while limiting the windows on the other sides, especially the north side will greatly contribute to passive solar heat gain in the winter. Limiting windows on the shady sides will also help to keep conditioned air from exiting quite as quickly; therefore reducing heating and cooling loads. Thick walls can also be of some help. Thick walls such as insulated concrete forms or ICF’s will soak up heat during the day to be released at night. This will also reduce heating loads. A light colored roof is a nice trick for the summer. The light color will reflect the sun and keep the attic from heating up. This is extremely important if you have ductwork in the attic. It will also help to extend the life of your roof.
Passive solar should be incorporated into every house that is built. The basic items I listed above such as facing the house properly, limiting windows on certain sides based on the climate, and having the right roof color should not cost anything additional during construction, but it does require a little thought before building. It’s a shame that the common sense of the past has disappeared in the wake of cheap energy.
3. Chiras, Dan., “The Homeowners Guide to Renewable Energy,” March 2006.