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added overhang shading implementation for #1467 #1468

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14b2fa0
added overhang shading implementation for #1467
Mathadon Oct 18, 2025
cf888f5
avoiding division by zero for #1467
Mathadon Oct 18, 2025
e5bf235
overhang support in outerwalls for #1467
Mathadon Oct 19, 2025
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14 changes: 13 additions & 1 deletion IDEAS/Buildings/Components/OuterWall.mo
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,12 @@ model OuterWall "Opaque building envelope construction"
parameter Modelica.Units.SI.Length dh(min=-hWal) = 0
"Height difference between top of object and top of wall"
annotation (Dialog(group="Building shade", enable=hasBuildingShade));
parameter Modelica.Units.SI.Length LOv(min=0) = 0
"Distance between overhang edge and wall, perpendicular to wall"
annotation (Dialog(group="Building shade", enable=hasBuildingShade));
parameter Modelica.Units.SI.Length dhOv(min=-hWal) = 0
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@jelgerjansen jelgerjansen Oct 20, 2025

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I would apply the min attribute in the BuildingShade model, in case someone uses this model for e.g. a window.

"Height difference between bottom of overhang and top of wall"
annotation (Dialog(group="Building shade", enable=hasBuildingShade));
parameter Modelica.Units.SI.Length hWal(min=0) = 0 "Wall height"
annotation (Dialog(group="Building shade", enable=hasBuildingShade));
final parameter Real U_value=1/(1/8 + sum(constructionType.mats.R) + 1/25)
Expand Down Expand Up @@ -52,6 +58,8 @@ model OuterWall "Opaque building envelope construction"
final haveBoundaryPorts=false,
final L=L,
final dh=dh,
final LOv=LOv,
final dhOv=dhOv,
final hWin=hWal) if hasBuildingShade
constrainedby IDEAS.Buildings.Components.Shading.Interfaces.PartialShading(
final azi=aziInt)
Expand Down Expand Up @@ -304,6 +312,10 @@ The correct shading parameter values should then be passed through the redeclara
</html>", revisions="<html>
<ul>
<li>
October 19, 2025 by Filip Jorissen:<br/>
Added support for shading overhangs <a href=\"https://github.com/open-ideas/IDEAS/issues/1467\">#1467</a>.
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@jelgerjansen jelgerjansen Oct 20, 2025

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Added support for shading overhangs.
See <a href="https://github.com/open-ideas/IDEAS/issues/1467\">#1467

</li>
<li>
August 18, 2025, by Klaas De Jonge:<br/>
Changed inc to incInt where nececarry.
</li>
Expand Down Expand Up @@ -386,4 +398,4 @@ Adjusted implementation for grouping of solar calculations.
</li>
</ul>
</html>"));
end OuterWall;
end OuterWall;
81 changes: 58 additions & 23 deletions IDEAS/Buildings/Components/Shading/BuildingShade.mo
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Expand Up @@ -7,15 +7,23 @@ model BuildingShade
parameter Modelica.Units.SI.Length L(min=0)
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Update model documentation: "Component for modeling shade cast by distant opposite objects such as buildings and treelines and/or an overhang"

"Distance to object perpendicular to window"
annotation (Dialog(group="Dimensions (see illustration in documentation)"));
parameter Modelica.Units.SI.Length LOv(min=0) = 0
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I would unify the parameter naming of this model and the Overhang model. So either:

  1. dep (as used in the Overhang model)
  2. LOve (use three characters) and apply this change to the Overhang model as well

"Overhang length perpendicular to window"
annotation (Dialog(group="Dimensions (see illustration in documentation)"));
parameter Modelica.Units.SI.Length dh
"Height difference between top of object and top of window glazing"
annotation (Dialog(group="Dimensions (see illustration in documentation)"));
parameter Modelica.Units.SI.Length dhOv = 0
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gap or dhOve

"Height difference between bottom of overhang and top of window glazing"
annotation (Dialog(group="Dimensions (see illustration in documentation)"));
parameter Modelica.Units.SI.Length hWin(min=0) = 1
"Window height: distance between top and bottom of window glazing"
annotation (Dialog(group="Dimensions (see illustration in documentation)"));
parameter Real fraSha(min=0,max=1) = 1
"Fraction of the light that is shaded, e.g. smaller than 1 for shading cast by tree lines.";
final parameter Real fraSunDifSky(final min=0,final max=1, final unit="1") = 1-vieAngObj/(Modelica.Constants.pi/2)
"Fraction of the light that is absorbed, e.g. smaller than 1 for shading cast by tree lines.";
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Fraction of the light that is absorbed by the opposite object

parameter Real fraShaOv(min=0,max=1) = fraSha
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fraShaOve

"Fraction of the light that is absorbed for overhang, e.g. smaller than 1 for shading cast by screens.";
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  1. absorbed by the overvang
  2. I find the example somewhat weird. Couldn't you say something like "equal to 1 for a concrete overhang and smaller than 1 for a glass overhang"

final parameter Real fraSunDifSky(final min=0,final max=1, final unit="1") = max(0, 1-(vieAngObj + vieAngOv)/(Modelica.Constants.pi/2))
"Fraction of window area exposed to diffuse sun light";

Real fraSunDir(final min=0,final max=1, final unit="1")
Expand All @@ -24,37 +32,60 @@ model BuildingShade
// Computation assumes that window base is at ground level.
// Viewing angle computed from center of glazing.
protected
final parameter Boolean haveOverhang = LOv > Modelica.Constants.small
"To avoid divisions by zero and obsolete computations";
parameter Modelica.Units.SI.Angle vieAngObj=atan((hWin/2 + dh)/L)
"Viewing angle of opposite object";
parameter Modelica.Units.SI.Angle vieAngOv=if haveOverhang then Modelica.Constants.pi/2 - atan((hWin/2 + dhOv)/LOv) else 0
"Viewing angle of overhang";
Comment on lines 37 to +40
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  1. Isn't view factor a better word?
  2. I would expect vieAngOve to be equal to atan(LOve/(hWin/2+dhOve)). How did you derive your expression?

final parameter Modelica.Units.SI.Angle rot=0
"Rotation angle of opposite building. Zero when parallel, positive when rotated clockwise"
annotation (Evaluate=true);
final parameter Real coeff = 1-fraSha "More efficient implementation";
final parameter Real hWinInv = 1/hWin "More efficient implementation";
final parameter Real coeff = 1-fraSha
"More efficient implementation";
final parameter Real coeffOv = 1-fraShaOv
"More efficient implementation";
final parameter Real hWinInv = 1/hWin
"More efficient implementation";
Comment on lines +44 to +49
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  1. Update parameter declaration to something like "Intermediate parameter to simplify model equations and expressions"
  2. Do you really need the coeff parameters? I guess the final expressions are more understandable if fraSha and fraShaOve are directly used.

Real tanZen = tan(min(angZen, Modelica.Constants.pi/2.01));
Modelica.Units.SI.Length L1
Modelica.Units.SI.Length L1 = max(0, L/cos(verAzi))
"Horizontal distance to object when following vertical plane through sun ray";
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"opposite object" (clarify now that the model has two different shading objects)

Modelica.Units.SI.Length L2
"Distance to object, taking into account sun position";
Modelica.Units.SI.Angle alt=(Modelica.Constants.pi/2) - angZen;
Modelica.Units.SI.Angle verAzi
Modelica.Units.SI.Length L2 = L1*tan(alt)
"Maximum height of object before it casts some shade";
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"opposite object" (clarify now that the model has two different shading objects)

Modelica.Units.SI.Length L1Ov = max(0, LOv/cos(verAzi))
"Horizontal distance to overhang edge when following vertical plane through sun ray";
Modelica.Units.SI.Length L2Ov = L1Ov*tan(alt)
"Minimum vertical distance between overhang and window before overhang casts some shade";
Modelica.Units.SI.Angle alt=(Modelica.Constants.pi/2) - angZen
"Solar altitude angle";
Modelica.Units.SI.Angle verAzi = Modelica.Math.acos(cos(angInc)/cos(alt))
"Angle between downward projection of sun's rays and normal to vertical surface";
initial equation
assert(fraSunDifSky>=0 and fraSunDifSky<=1, "In " + getInstanceName() +
": The parameter fraSunDifSky has the value " +String(fraSunDifSky) + " and
should be within [0,1]. Please contact the IDEAS developers.");


equation

verAzi = Modelica.Math.acos(cos(angInc)/cos(alt));
L1 = max(0,L/cos(verAzi));
L2 = L1*tan(alt);
if noEvent(L2<dh) then
fraSunDir=coeff;
elseif noEvent(L2<dh+hWin) then
fraSunDir=coeff + (L2-dh)*fraSha*hWinInv;
// the below implementation does not yet consider the case where both overhang and object
// cast shade at the same time

if haveOverhang then
if noEvent(L2<dh) then
fraSunDir=coeff;
elseif noEvent(L2<dh+hWin) then
fraSunDir=coeff + (L2-dh)*fraSha*hWinInv;
elseif noEvent(L2Ov>dhOv+hWin) then
fraSunDir=coeffOv;
elseif noEvent(L2Ov>dhOv) then
fraSunDir=coeffOv + (L2Ov-dhOv)*fraShaOv*hWinInv;
Comment on lines +69 to +76
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You first check L2 and then L2Ove, is it always guaranteed that only 1 elseif statement is true?

else
fraSunDir=1;
end if;
else
fraSunDir=1;
if noEvent(L2<dh) then
fraSunDir=coeff;
elseif noEvent(L2<dh+hWin) then
fraSunDir=coeff + (L2-dh)*fraSha*hWinInv;
else
fraSunDir=1;
end if;

end if;

HShaDirTil=fraSunDir*HDirTil;
Expand Down Expand Up @@ -96,6 +127,10 @@ can be modelled by changing the value of parameter <code>fraSha</code> according
</html>", revisions="<html>
<ul>
<li>
October 18, 2025 by Filip Jorissen:<br/>
Added support for shading overhangs <a href=\"https://github.com/open-ideas/IDEAS/issues/1467\">#1467</a> and updated documentation image.
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Added support for shading overhangs and updated documentation image.
See <a href="https://github.com/open-ideas/IDEAS/issues/1467\">#1467

</li>
<li>
July 18, 2022 by Filip Jorissen:<br/>
Refactored for <a href=\"https://github.com/open-ideas/IDEAS/issues/1270\">#1270</a> for including thermal effect of screens.
</li>
Expand Down
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