Roof Overhang Shading

Overhang depth for solar heat gains and shade.

Roof overhang shading.

There are two common problems encountered with roof overhangs. Using sketchup i just fiddled around with the overhang width window size and vertical placement until i got the desired shading effect. That might be desirable during winter months but very uncomfortable during hot summer months. Overhangs are most effective for south facing elements in the northern hemisphere and at midday.

A value of 73 for example indicates that the overhang is shading about 27 of the window area and 73 of the window is in the sun. In passive solar home design exterior roof overhangs provide a practical method for shading building elements such as windows doors and walls. Shade each data cell has the percentage of shade listed in addition to the background color as an indicator. The depth of roof overhangs is crucial in cold and moderate climates where oversized overhangs will have negative side effects.

Because the sun travels different paths across the sky in the winter low and summer high time an overhang can be constructed to utilize and manipulate the heat energy from the sun. For example if the roof s overhang does not shade the window during the hottest hours of the day direct and reflected sun light will heat the interior. The shade is in 1 increments. In the first case the overhang is simply too big for the home.

The roof overhang does not extend far enough. You may use wide overhangs and verandas in hot climates without a cold season and in hot wet climates with high levels of rainfall but oversized overhangs in other. An overhang or some sort of solar control or solar shading is a crucial element in passive solar design because it blocks the sun s heat energy when it is not desired. The sun is in 1 increments.

For hot humid climates and hot dry climates with no heating requirements shade the whole building at all times with eaves overhangs of 50 of height from floor level to both north and south where possible and use planting or adjoining buildings where it is not possible. This leads to a situation where there is an excess amount of shade and the exterior of the home appears dark and gloomy. The roof overhang is too wide. The following snips show shading at noon on april 16 june 21 september 1 december 1 and february 1.