SOL_FCD: Solar function facade

The SOL_FCD (FB555) calculates the relative position of the sun (relative to the facade orientation) from the solar position (as calculated for the building location). The relative solar position provides through both angles the relative solar elevation (angle of the sun to the facade horizon) and relative solar azimuth (azimuth angle of the sun versus the orientation of the facade).

Another calculated output variable is the project solar elevation angle. This angle is useful for adjusting blinds to the position of the sun. It is the equivalent angle for a constant relative solar azimuth angle of 0°.

Solar radiation direction is also outputted and indicates whether sun is shining on the facade. Angle ranges may be provided (azimuth angle range and elevation angle range), providing an easy way to consider the effects of fixed shading facilities.

Application

Used as a component for adjusting blinds.
Used as a component for anti-glare functions.
Used as a component for overheating protection.

Functionality

Facade and solar angle for calculation.

The following illustrates how facade and solar angles are defined.

View of angle ranges

Below is an example for defining the angle ranges right and left for a vertical southeast facing facade.

The ranges are selected in the so that no direct radiation can penetrate the room interior.

Solar radiation direction

Solar radiation direction [SolRdDir] = 1 (Yes) is set if all of the following conditions are met:

The absolute solar elevation angle [SolEtHor] is greater or equal to zero (i.e. only during the day).
The projected solar elevation angle [SolEtRel] is less than the angle range above: [PrjAgl] < +[AglUp].
The projected solar elevation angle [SolEtRel] is greater than the negative angle range below: [PrjAgl] > -[AglDown].
The relative azimuth angle [SolAzRel] is less than the angle range right: [SolAzRel] < +[AglRight].
The relative azimuth angle [SolAzRel] is greater than the negative angle range left: [SolAzRel] > -[AglLeft].

In the conditions, the relative azimuth angle [SolAzRel] must be used with the range (-180°…180°)!

Inputs

Pin	E	Description
SolAzmth	pa	Solar azimuth angle, calculated in SOL_POS
		0°	North.
		90°	East.
		180°	South.
		270°	West.
SolEtHor	pa	Solar elevation angle for horizon, calculated in SOL_POS.
		0°	Sun on the horizontal plane.
		90°	Sun at its zenith.
FcdAzmth	pa	Facade orientation: Azimuth of the facade. Note for engineering: Corresponds as well to the definition at SOL_CNV.
		0°	North-facing facade.
		90°	East-facing facade.
		180°	South-facing facade.
		270°	West-facing facade.
FcdIncl	pa	Facade orientation: Facade tilt angle. Note for engineering: Corresponds as well to the definition at SOL_CNV.
		0°	Horizontal facade facing up (zenith).
		90°	Vertical facade (standard).
AglLeft	pa	Angle range left. The angle range of the relative azimuth angle accessible to direct radiation starting from the normal facade to the left side (as viewed from inside the building).
AglRight	pa	Angle range right The angle range of the relative azimuth angle accessible to direct radiation starting from the normal facade to the right side (as viewed from inside the building).
AglUp	pa	Angle range up The angle range of the projected solar elevation angle accessible to direct radiation starting from a normal facade upward. [TBD:] Grafics
AglDown	pa	Angle range down The angle range of the projected solar elevation angle accessible to direct radiation starting from a normal facade downward.

Outputs

Pin	E	Description
SolAzRel	a	Relative solar azimuth angle.
SolEtRel	a	Relative solar elevation angle.
PrjAgl	a	Projected solar angle of entry.
SolRdDir	a	Direct solar radiation on the facade. Requirements

Input values

Pin	Description	Data type.	Default value	E.g. Engineering unit or Text group	Min.	Max.
SolAzmth	Solar azimuth angle.	Real	180.0	degAngl	-360.0	360.0
SolEtHor	Solar elevation.angle f.horizon.	Real	0.0	degAngl	-90.0	90.0
FcdAzmth	Azimuth of the facade.	Real	180.0	degAngl	-360.0	360.0
FcdIncl	Facade incline.	Real	90.0	degAngl	-180.0	180.0
AglLeft	Angle range left.	Real	85	degAngl	-180.0	180.0
AglRight	Angle range right	Real	85	degAngl	-180.0	180.0
AglUp	Angle range up	Real	85	degAngl	-180.0	180.0
AglDown	Angle range down	Real	85	degAngl	-180.0	180.0

Output values

Pin	Description	Data type.	Default value	E.g. Engineering unit or Text group	Min.	Max.
SolAzRel	Relative solar azimuth angle.	Real		degAngl
SolEtRel	Relative solar elevation angle.	Real		degAngl
PrjAgl	Project solar angle of entry.	Real		degAngl
SolRdDir	Direct solar radiation facade.	Boolean	0 (No)	No, Yes

Example

Example 1: Vertically standing facade.

Constant input variable: FcdAzmth = 180°, FcdIncl = 90° (south facing).

AglLeft = 90°, AglRight = 90°, AglUp = 90°, AglDown = 90°

Input variable varying by time: SolEtHor and SolAzmth as calculated for Zug (longitude 8.52°, latitude 47.17°) for May 20, 2010 (local time).

Diagrams:

[SolAzmth] = Solar azimuth angle.

[SolAzRel] = Relative solar azimuth angle.

[SolEtHor] = Solar elevation angle for horizon.

[SolEtRel] = Relative solar elevation angle.

[PrjAgl] = Projected solar angle of entry.

[SolRdDir] = Direct solar radiation facade.

Time curve for SolAzmth, SolEtHor (input variables), SolAzRel, SolEtHor, SolEtRel, PrjAgl, SolRdDir (output variables) and NightDay (Information, not directly calculated by the function) for example 1.

Example 2: Tilted facade

Constant input variable: FcdAzmth = 180°, FcdIncl = 45° (south facing, 45° tilt).