Bentley Systems, Inc (CAD/CAM Software Production) | GenerativeComponents (GC) | Parametric Modeling Software

Fall - Winter 2014







Running Process in Local and Cloud Modes


Research on the Identity of the Vertical Sky Component Value and Standard 

Developing the Analyzer node for calculation of VSC Value in the Analysis Add-in part


Development Environment:

Visual Studio 2008, C#, GC script, C++

GenerativeComponents ( GC Core and GC Add-ins for Optimization, Structural, Energy and Inolation Analysis)

PowerPlatform : MicroStation




Work in Progress


What is Vertical SKY Component (VSC)?

How VSC has to be calculated?


The Vertical Sky Component is a measure of the amount of skylight incident on a vertical plane (it is the Sky Factor on a Vertical Plane). It is most commonly applied to the light incident at the center of a window and in this sense is a measure of the potential for good daylighting. The VSC is calculated by taking the ratio of the skylight incident at a point to the unobstructed skylight available at that same point on a horizontal plane. For a uniform sky, the maximum value is 50% (since the point is on a vertical plane, clearly only half the hemisphere can contribute). For a CIE sky, the maximum value is 39.6%.


Clearly, the further down the windows are, the less light they receive, and the lower the value of the VSC.















BRE Criterion
The guidelines state that if the VSC at the centre of a window is less than 27% and less than 0.8 times its former value, the diffuse daylighting of the existing building will be adversely affected. A value of 27% corresponds to an infinite obstruction angle of 25 degrees. This guideline (as with all the BRE guidelines) can be interpreted flexibly. The above criterion was developed in the case of suburban development where existing development was 2 storeys across an average street width. In city centre locations, the target VSC can be reduced to allow proposed buildings to match the height of other buildings in the neighbourhood.

Reference :


VSC calculator


VSC Analyzer node is placed in part of the Environmental Analysis and in Insolation analysis GC Add-in plug in


The way of access to the VSC analyzer node in GC environment:

Implementation of the VSC Analyzer node, it's structure and required inputs and outputs