You may have already heard that House & Garden Magazine took a green approach in its latest installment, the February issue I believe.  One article talks about an interview with William McDonough, in which he mentions the orientation of a home.  Earlier, I blogged about Global Green USA’s Top 20 list of low- or no-cost green building strategies and orientation was #1.  Regarding orientation, the rule is to "orient a building to maximize natural daylighting."  As part of the orientation process, one needs to find a building’s true south and build it in such a way, to maximize sun exposure/non-exposure, and thereby, optimize energy-efficiency (i.e., use the sun instead of artificial lighting, use the sun’s warmth instead of heating, use the shade’s cool instead of air conditioning, etc.). 

McDonough pointed out that many architects and builders don’t know how to find true south.  If a compass is used, the compass indicates south, which can differ from true south by more than 15 degrees.  Remember, orienting a home is about orienting the home to sun exposure, not magnetic south.  To find true south, one needs two things:  (1) to know your geography’s solar noon, and (2) to use the sun to draw perfect north/south line exactly at solar noon.  Solar noon is the time when the sun hits the highest point in the sky and can be found using the following Sunrise/Sunset Calculator.  Once the solar noon is figured out, take a line with a weight attached to it, hold it up in the air at solar noon, and the shadow line will reveal the proper north/south orientation of a home.  That line will point to true south and will help you build the home properly, assuming you have some latitude in deciding the orientation of the home.