Passive solar design refers to the use of the sun's energy to help heat and cool your home or office. In this approach, the building itself takes advantage of the suns natural energy by exposing the interior spaces to the suns energy in winter and blocking the sun from entering the interior in summer. The placement of a home on a building site is the single most important way to achieve a passive solar design.
Locating your home within twenty degrees plus or minus in either direction of true South coupled with calculated overhangs over your windows is the single most important "Passive Solar" design detail achievable. Here is how it works; the sun's path runs south on its zenith, during the longest day of the year (Summer Solstice, June 21st,) the sun is at its highest southern angle of approximately 75 deg., during the shortest day of the year (Winter Solstice December 22nd,) the sun is at its lowest southern angle of approximately 35deg. This natural occurrence makes for a very simple solution to control the suns energy as you can see in the illustrations. This aspect of a passive solar system is a no brainer, having no moving parts, requires no maintenance, no mechanical systems, and it does not cost anything to do in most cases. It will save you money every month that you need to heat or cool your home. And it promotes sustainability, helping all of us make a contribution without reaching further than our own home.