Green Building: Finding True South to Optimize Orientation

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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.


  • http://cornellbox.livejournal.com Philip Proefrock

    It’s not only knowing where due south is, but also having a building that works with that orientation.

    Given a site plan or legal description, any competent surveyor should be able to lay out a building with the proper orientation. But having a building that is designed to perform properly in that orientation is, I think, the far more difficult part.

    I recently saw a mailing-list discussion about finding “green” house plans that addressed this same issue: Why aren’t there “green plan books”? You point out exactly why; because people would build from a plan designed for a particular orientation, but would turn it some other way, and then wonder why it performed so badly.

  • samir hashim

    good

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