.Buildings.BoundaryConditions.SolarIrradiation.BaseClasses.SkyClearness

Information

This component computes the sky clearness.

Implementation

In the Buildings library, HDirNor is always larger than 1E-4, minus some small undershoot due to regularization. Hence, the implementation is not simplified for HDirNor < Modelica.Constants.small.

The function call Buildings.Utilities.Math.Functions.smoothMax is such that the regularization is usually not triggered.

Revisions

• March 4, 2024, by Michael Wetter:
  Corrected displayUnit.
  This is for IBPSA, #1848.
• September 6, 2021, by Ettore Zanetti:
  Changed lat from being a parameter to an input from weather bus.
  Changed input connector HGloHor to HDirNor.
  This is for IBPSA, #1477.
• May 2, 2021, by Ettore Zanetti:
  Corrected expression for sky clearness.
  This is for issue 1477.
• September 23, 2016, by Michael Wetter:
  Changed deltaX from 0.1 to 0.01, and also optimized the code.
  This is for issue 521.
• May 5, 2015, by Michael Wetter:
  Introduced constant k to reduce number of operations.
• May 5, 2015, by Filip Jorissen:
  Converted algorithm section into equation section for easier differentiability.
• July 07, 2010, by Wangda Zuo:
  First implementation.