For a window with an overhang, this block outputs the fraction of the area that is exposed to the sun. This models can also be used for doors with an overhang.
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 overhang can be asymmetrical (i.e. wR ≠ wL
)
about the vertical centerline
of the window.
The overhang must completely cover the window (i.e.,
wL ≥ 0
and
wR ≥ 0
).
wL
and wR
are measured from the left and right edge of the window.
The surface azimuth azi
is as defined in
Buildings.Types.Azimuth.
The method of super position is used to calculate the window shaded area. The area below the overhang is divided as shown in the figure.
Dimensional variables used in code for the rectangle DEGI, AEGH, CFGI and BFGH are shown in the figure below:
The rectangles DEGI, AEGH, CFGI and BFGH have the same geometric configuration
with respect to the overhang.
Thus, the same algorithm can be 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 window ABCD, the shaded portion of AEGD and CFGI
should be subtracted from that of DEGI and BFGH.
This shaded area of the window is then divided by the total window area
to calculate the shaded fraction of the window.
lat
because the latitude is now obtained from the weather data bus.shdwTrnglRtio*x1 = y1
to avoid a division by
zero if the model is exported as an FMU.wL
and wR
to be
measured from the corner of the window instead of the centerline.
This allows changing the window width without having to adjust the
overhang parameters.