18 24 is a good rule of thumb i use 24 w a energy heel.
Roof overhangs for passive solar.
We design them primarily to shed water away from the foundation wall depending on wind direction orientation etc.
Erik not sure what kind of insolation you receive at your site but it might be worth it to consider the.
Here s a link to a free web based tool to help you size roof overhangs on a passive solar building.
An important component of passive solar design is calculating building openings doors and windows and roof overhangs.
In passive solar home design exterior roof overhangs provide a practical method for shading building elements such as windows doors and walls.
Of course we don t want to solar shade either unless intentionally.
You can use the free software sketchup to draw the house and it will draw sun shadows for any date time at your location.
Overhangs are most effective for south facing elements in the northern hemisphere and at midday.
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Jonr senior member posts 5341.
Cost effective passive solar design.
I also urge you to read this article.
There is simulation software like sam to do this if you want even site phone apps we use it to design solar panels systems.
Design solar altitude angle for full sun deg from passive solar altitude angle calculator build height of roof overhang from top of glass feet or leave blank build depth of roof overhang from glass feet or leave blank requested solution 0 full shade full sun 1 full shade 2 full sun.
How roof overhangs work.
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.
User 757117 jul 16 2012 05 54pm 3.
24 dec 2012 02 45 pm.
For instance several features of a window will influence gain of solar heat and shade.
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.
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.
We don t design overhangs primarily for passive solar these days old design rules no longer apply.
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.