modelFixedShade

Model for exterior shade due to overhang and/or side fin

Extends from HeatTransfer.Windows.BaseClasses.ShadeInterface_weatherBus (Base class for models of window shade and overhangs).

Information

This model outputs the fraction of the window area that is sun exposed for a window that may have an overhang and sidefins. Depending on the record with construction data conPar, an overhang, side fins or no external shade is modeled. The model allows having an overhang and side fins at the same time. In such a case, the overhang width should be measured from the window edge to the sidefin, because the overhang width beyond the sidefin will cast a shadow on the side fin and not on the window. Similarly, the side fin height should be measured from the upper window edge to the overhang, because the side fin height above the overhang will not cast a shadow on the window. The parameters for the dimensions of the overhang and side fins are as described in the models Buildings.HeatTransfer.Windows.Overhang and Buildings.HeatTransfer.Windows.SideFins.

Limitations

For overhangs, the model assumes that

the overhang is at least as wide as the window, i.e., w_L ≥ 0 and w_R ≥ 0, and
the overhang is horizontal.

For side fins, the model assumes that

the side fins are placed symmetrically to the left and right of the window,
the top of the side fins must be at an equal or greater height than the window, and
the side fins extends at least to the lower edge of the window.

Implementation

The detailed calculation method is explained in Buildings.HeatTransfer.Windows.BaseClasses.SideFins and in Buildings.HeatTransfer.Windows.BaseClasses.Overhang.

Parameters

Type	Name	Default	Description
Buildings.ThermalZones.Detailed.BaseClasses.ParameterConstructionWithWindow	conPar		Construction parameters
Modelica.Units.SI.Angle	azi		Surface azimuth; azi= -90 degree East; azi= 0 South

Connectors

Type	Name	Description
Buildings.BoundaryConditions.WeatherData.Bus	weaBus (from ShadeInterface_weatherBus)	Weather data bus
Modelica.Blocks.Interfaces.RealInput	incAng (from ShadeInterface_weatherBus)	Solar incidence angle
Modelica.Blocks.Interfaces.RealInput	HDirTilUns (from ShadeInterface_weatherBus)	Direct solar irradiation on tilted, unshaded surface
Modelica.Blocks.Interfaces.RealOutput	HDirTil (from ShadeInterface_weatherBus)	Direct solar irradiation on tilted, shaded surface
Modelica.Blocks.Interfaces.RealOutput	fraSun (from ShadeInterface_weatherBus)	Fraction of the area that is unshaded

Components

Type	Name	Description
Modelica.Blocks.Routing.Multiplex4	mulFraSun	Multiplex for fraction of shaded area
Modelica.Blocks.Math.Add	sumFraSun	Addition of sun exposed window area fractions
Modelica.Blocks.Math.Add	resFraSun	Calculates resultant sun exposed window area fraction
Modelica.Blocks.Sources.Constant	overlap	Overlap of sun exposed window area fraction
Modelica.Blocks.Sources.Constant	noSunCond	Condition when the sun is not in front of window

Revisions

September 16, 2021, by Michael Wetter:
Removed parameter lat because the latitude is now obtained from the weather data bus.
This is for IBPSA, #1477.
May 30, 2014, by Michael Wetter:
Removed undesirable annotation Evaluate=true.
July 7, 2012, by Michael Wetter:
Renamed model from Shade to FixedShade because shade is already used for window interior and exterior shades.
July 5, 2012, by Michael Wetter:
Moved model from package Buildings.ThermalZones.Detailed.BaseClasses to Buildings.HeatTransfer.Windows, because the overhang and side fin models are also in this package.
May 21, 2012, by Kaustubh Phalak:
Enabled the model to use overhang and side at the same time.
March 5, 2012, by Michael Wetter:
First implementation.