[SOL_FCD] Solar function facade
Function block SOL_FCD calculates the relative solar position from the actual solar position.
SOL_FCD calculates the relative solar position (relative to facade orientation) from the solar position calculated for the building location. The relative solar position is given by relative solar elevation and relative solar azimuth. The relative solar elevation is calculated from the angle between the sun and facade horizon. The relative solar azimuth is calculated from the angle of the solar azimuth angle and facade orientation.
Another calculated output variable is the projected solar elevation angle. This angle is used to adjust blinds to the solar position. It is the equivalent angle for a constant relative solar azimuth angle of 0°.
Solar radiation direction is also provided and indicates if the sun is shining onto the facade. Angle ranges can be set (azimuth angle range and elevation angle range) to easily include fixed shading facilities.
Facade and solar angle for calculation
Angle ranges to the right and left for a vertical, South-East-facing facade
The ranges are selected in the illustration so that no direct radiation can penetrate the room interior.
Solar radiation direction
If all of the following conditions are met, solar radiation direction [SolRdDir] = 1 is set:
- The absolute solar elevation angle is greater or equal to zero (i.e. only during the day).
- The projected solar elevation angle is less than the angle range above: PrjAgl < +AglUp.
- The projected solar elevation angle is greater than the negative angle range below: PrjAgl > -AglDown.
- The relative azimuth angle is less than the angle range right: SolAzRel < +AglRight.
- The relative azimuth angle is greater than the negative angle range left: SolAzRel > -AglLeft.
The relative azimuth angle with range -180...180° is used.
Input | Description | Data type | Default value |
|---|---|---|---|
SolAzmth | Solar azimuth angle Solar azimuth angle, calculated in SOL_POS | Real | 180.0 -360.0…360.0 |
0°: North | |||
SolEtHor | Solar elevation angle from horizon | Real | 0.0 -90.0…90.0 |
0°: Sun on the horizontal plane | |||
FcdAzmth | Facade orientation: Facade azimuth angle Note | Real | 180.0 -360.0…360.0 |
0°: North-facing facade. | |||
FcdIncl | Facade orientation: Facade angle of inclination Note | Real | 90.0 |
0°: Horizontal facade facing up (zenith). | |||
AglLeft | Angle area 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). | Real | 85.0 -180.0…180.0 |
AglRight | Angle area 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). | Real | 85.0 -180.0…180.0 |
AglUp | Angle area up The angle range of the projected solar elevation angle accessible to direct radiation starting from a normal facade upward. | Real | 85.0 -180.0…180.0 |
AglDown | Angle area down The angle range of the projected solar elevation angle accessible to direct radiation starting from a normal facade downward. | Real | 85.0 -180.0…180.0 |
Output | Description | Data type | Default value |
|---|---|---|---|
SolAzRel | Relative solar azimuth angle | Real | 0.0 |
SolEtRel | Relative solar elevation angle | Real | 0.0 |
PrjAgl | Projected solar incidence angle | Real | 0.0 |
SolRdDir | Direct solar radiation on facade | Boolean | 0 |
0 - No | |||
SOL_FCD is used as a component for:
- Adjusting blinds
- Anti-glare functions
- Overheating protection
Example 1: Vertical facade.
Constant input variables: FcdAzmth = 180°, FcdIncl = 90° (South facing).
AglLeft = 90°, AglRight = 90°, AglUp = 90°, AglDown = 90°
Input variables varying by time: SolEtHor and SolAzmth as calculated for Zug (longitude 8.52°, latitude 47.17°) for May 20, 2010 (local time).
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:
Key
SolAzmth | Solar azimuth angle |
SolAzRel | Relative solar azimuth angle |
SolEtHor | Solar elevation angle from horizon |
SolEtRel | Relative solar elevation angle |
PrjAgl | Projected solar incidence angle |
SolRdDir | Direct solar radiation on facade
|
Example 2: Tilted facade
Constant input variables: FcdAzmth = 180°, FcdIncl = 45° (South-facing, 45° tilt).
AglLeft = 90°, AglRight = 90°, AglUp = 90°, AglDown = 90°
Input variables varying by time: SolEtHor and SolAzmth as calculated for Zug (longitude 8.52°, latitude 47.17°) for May 20, 2010 (local time).
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 2:
Key
[SolAzmth] | Solar azimuth angle |
[SolAzRel] | Relative solar azimuth angle |
[SolEtHor] | Solar elevation angle from horizon |
[SolEtRel] | Relative solar elevation angle |
[PrjAgl] | Projected solar incidence angle |
[SolRdDir] | Direct solar radiation on facade
|