Quick Answer
Identify the right location for south windows by finding a spot that receives direct sunlight between 9 and 3 pm during the winter months. This spot should be sheltered from prevailing winds and winter snow load. South-facing windows should be at least 30 degrees south of the equator.
Understanding the Sun’s Path
When placing south windows, consider the sun’s path across the sky. In the winter, the sun is lower in the sky and closer to the south, while in the summer it is higher and more to the southeast. Use a surveyor’s transit or a smartphone app to determine the exact direction of south at your location. This will ensure that your south windows receive the most direct sunlight during the winter months when passive solar heating is most beneficial.
Measuring the Angle
A common rule of thumb for south windows is to place them at an angle of 30-40 degrees from the horizontal. This allows for optimal winter sun exposure while minimizing summer sun glare. To achieve this angle, build a frame or use a tilt-adjustable window that can be set to this angle. You can also use a string and a level to mark the angle on your wall before installing the window.
Considering Local Climate and Building Orientation
In addition to the sun’s path, consider your local climate and building orientation when placing south windows. If you live in a region with frequent snowfall or high winds, place windows higher on the wall to reduce snow load and wind-driven moisture. If your building is oriented northwest-southeast, place windows on the southeast wall to capture winter sun and reduce summer sun exposure.
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