.IDEAS.Buildings.Components.Shading.HorizontalFins

Information

Shading model for exterior horizontal fins in front of a window, in function of the fin angle. The control input Ctrl can either be used for controlling the fin angle, or its horizontal displacement. The horizontal displacement option assumes that the fins can be displaced horizontally at the exterior of the window such that they are either in front or next to the window.

Assumption and limitations

We assume that the fins fully cover the window unless the horizontal displacement option is used. The fin angle beta should be positive. We compute the shaded fraction of the direct solar irradiation and assume that indirect reflect effects are negligible. The diffuse solar irradiation is correct by assuming that the diffuse solar irradation originates from a solar altitude angle of 30 degrees, which is an approximation to reality. The ground diffuse solar irradation is not modified.

Typical use and important parameters

Parameter t is the fin thickness, s is the vertical spacing between the fins and w is the fin width. If use_betaInput=true, the input Ctrl is used to control the angle beta, such that beta in the figure equals Ctrl. Note that beta must have radians as a unit. If use_displacementInput=true, the input 0 < Ctrl < 1 is used to control the horizontal displacement of the fins. For Ctrl=0, the fins are moved away from the window, into the plane of the figure below, such that no sun light is blocked. Either use_displacementInput or use_betaInput should be false. See the figure below for an illustration.

Dynamics

This model has no dynamics.

Implementation

The implementation is illustrated using this figure:

Revisions

• November 10, 2019 by Filip Jorissen:
  Added simplified computation for diffuse solar shading. See #874.
• March 18, 2019 by Filip Jorissen:
  Added control option for horizontal displacement. Fixed bug in the implementation. See #992.
• April, 2017 by Iago Cupeiro:
  Cleaned up implementation and documentation.