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.
Roof overhang shading.
There are two common problems encountered with roof overhangs.
The roof overhang is too wide.
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.
Using sketchup i just fiddled around with the overhang width window size and vertical placement until i got the desired shading effect.
For hot dry climates with some heating requirements gradually increase the overhang up to 50 of height full shading.
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.
The roof overhang does not extend far enough.
The depth of roof overhangs is crucial in cold and moderate climates where oversized overhangs will have negative side effects.
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.
No i just made the overhangs wide enough to provide the extra shade.
In the first case the overhang is simply too big for the home.
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.
The shade is in 1 increments.
Overhang depth for solar heat gains and shade.
This leads to a situation where there is an excess amount of shade and the exterior of the home appears dark and gloomy.
Overhangs are most effective for south facing elements in the northern hemisphere and at midday.
The sun is in 1 increments.
How roof overhangs or other window overhangs work to control heat and solar gain.
The following snips show shading at noon on april 16 june 21 september 1 december 1 and february 1.
That might be desirable during winter months but very uncomfortable during hot summer months.