Roof Overhang For Solar Gain

With the window heights and overhangs i used in the model at noon on june 21 the entire glazing of the south elevation windows are completely in shadow but just barely.

Roof overhang for solar gain.

On the other hand some homeowners choose to embrace the look of solar panels by positioning them front and center in place of a patio awning or roof overhang. In order to better illustrate this principle in action. Borst passive solar roof overhang design calculator. If the building element bears more than about 30 off true south the effectiveness of an overhang as with any solar feature begins to decrease significantly.

The eaves overhang may also shelter openings to ventilate the roof space. This will help keep the house cooler in the summertime. How roof overhangs or other window overhangs work to control heat and solar gain overhangs are most effective for south facing elements in the northern hemisphere and at midday. The overhang or solar control is used to keep the building s thermal mass in the shade.

Think of how cool shaded tile or marble can feel on bare feet on a hot summer day. How do i determine the correct amount of shading sun. At noon on january 21 the glass is completely exposed. You can use the free software sketchup to draw the house and it will draw sun shadows for any date time at your location.

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. Jonr senior member posts 5341. The size of the window width and height and the window s relationship to the roof the space above the window influences the direct and indirect gain of solar heat. Solar awnings are a two in one win for energy efficiency.

Homeowners can take advantage of this natural phenomena by placing skylights on a south facing section of the roof near an overhang. 24 dec 2012 02 45 pm. They reduce solar heat gain in the summer by up to 65 percent on south facing windows and 77 percent on west facing windows. The skylight will allow the winter sun to enter and provide additional heat but the overhang will block the direct sun in the summertime so that solar gain does not work against cooling appliances.

These guidelines are useful in the construction of any gable or any cantilevered or flat roof. I used sketchup to help determine how the solar path would fall on the house i am designing. In hot climates the general rule of thumb is to lengthen and extend the overhang. The goal is to balance the amount of solar heat gain and amount of shading.