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Design fixed shading and roof overhangs

Overhangs on the sun-facing wall should block the high summer sun and let in the low winter sun. East and west windows need vertical shading because the sun is low there.

How

1. Calculate noon sun altitudes from latitude: equinox = 90 minus latitude; summer solstice adds 23.5 degrees; winter solstice subtracts 23.5 degrees (Your Home method).
2. For latitudes of 27.5 degrees and higher, Your Home sizes the eave projection at about 45 percent of the height from window sill to underside of eave, with the eave at least 30 percent of that height above the top of the glass.
3. Closer to the equator, or in hot climates with little heating, increase projection toward 50 percent of that height.
4. Below about 23.5 degrees latitude the summer noon sun is on the pole side of the house. In hot humid climates Your Home advises eaves of 50 percent of the height from floor level.
5. Your Home applies that tropical rule to both the north and south sides where possible, and says to shade all walls and openings. The overhang calculator switches to it below 23.5 degrees.
6. Extend horizontal shading past each side of the window by the same distance it projects.
7. Shade east and west glass with vertical louvres, screens, verandas, pergolas or deciduous planting, preferably adjustable.
8. Check winter solar access: windows should be unshaded from 9 am to 3 pm in winter (DOE). Mature deciduous trees can pass 60 percent or more of winter sun (DOE fact sheet).
9. Use the overhang calculator below, then check with a sun-path tool for your exact site.

Sources

1. Shading. Your Home, Australian Government, accessed 2026-11
2. Consumer Guide to Passive Solar Home Design. US Department of Energy, Energy Saver, accessed 2026-11
3. Passive Solar Design (Technology Fact Sheet DOE/GO102000-0790). US Department of Energy and NREL, accessed 2026-11

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