Replies

1. 
   chrisg | Feb 13, 2002 11:18pm | #1

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   I want to design an overhanging "skirt" around the top of the first floor of a two storey addition on the south and west face of my home. It will serve to block summer sun and admit winter sun into the house. How far out from the wall does it need to extend, using 6' high windows, on the 45th Parallel?

1. 
   Mike_Smith | Feb 13, 2002 11:36pm | #2

   *chrisg.. a good source for solar angles is Architectural Graphic Standards.....

1. 
   David_Thomas | Feb 20, 2002 11:23pm | #3

   *The earth tilts on its axis 22.3 degrees. So at 45 degrees lattitude (such as Portland, OR), the winter sun will be 22.7 degrees above the horizon at noon. And it will be 67.3 degrees up at noon on June 21st. Not that it is necessary to block absolutely all direct sunlight in the summer or admit all of it in the winter, but those are the extremes.I'd do sketches with the sun at 55 to 60 degrees and see what kind of overhangs shades 70-80% of your particular windows. That will deal with most of the solar input during the hottest months. Trying to block 100% in the summer with such tall windows would results in huge overhangs. Installing the windows as high on the wall as possible will help with the solar input. But consider the view which will result. (If you are mostly looking up at the soffit of a large overhang, why have such a big window?)The sun will be lower before and after noon, implying longer overhangs. And in the east and west, it will be much lower in the summer. At 6 pm in June, it will be blasting in from a height of about 10 - 15 degrees from the west. Hard to keep that out with an overhang.Also consider decidous trees that shade in the summer but drop leaves in the winter. Blinds. Bronzed windows for keeping the solar gain to a minimal (especially for west windows). Etc.Look at traditional designs in your area. Before central heating and whole-house A/C people were more motivated to build houses suited to their climate and location. -David