For a window with side fins, this block outputs the fraction of the area that is exposed to the sun. This models can also be used for doors with side fins.
Input to this block are the wall solar azimuth angle and the altitude angle of the sun. These angles can be calculated using blocks from the package Buildings.BoundaryConditions.SolarGeometry.BaseClasses.
The model assumes that
The method of super position is used to calculate the shaded area of the window. The area besides the side fin is divided as shown in the figure below.
Variables used in the code for the rectangle AEGI, BEGH, DFGI and CFGH are shown in figure below.
The rectangles AEGI, BEGH, DFGI and CFGH have the same geometric configuration
with respect to the side fin.
Thus, the same algorithm is used to calculate the shaded portion in these areas.
A single equation in the for
loop improves the total calculation time,
as compared to if-then-else
conditions, considering the various shapes of the shaded portions.
To find the shaded area in the window ABCD, the shaded portion of
BEGH and DFGI is subtracted from AEGI and CFGH.
This shaded area of the window is then divided by the total window area
to calculate the shaded fraction of the window.
h
to be
measured from the top of the window.
This allows changing the window height without having to adjust the
side fin parameters.