The student will show an understanding of the information by figuring out the proper overhang to provide shading for a dwelling. This is most critical when the south wall has windows and glass doors. The stud wall can be easily insulated to prevent heat from traveling through the wall, but when glass interrupts this well insulated wall, there is great potential for interior solar heat gain. To prevent this, the glass needs to be shaded.
Overhangs have a tendency to trap hot air under the soffit as it rises.
One way to eliminate this problem is to make the overhang louvered to permit rising heat to escape. These louvers could be adjustable to allow more sun to enter the interior during the winter. Another method to remove heat from below the soffit is a continual soffit vent where the soffit meets the wall. A method to calculate the correct overhang to provide the proper shading is to multiply the distance from the sill of the glass to the soffit by a factor based on the angles of the sun. There are different factors for each latitude because the sun is at different angles at each latitude.