Shadowing calculations in DesignBuilder default to the CPU-based polygon clipping method, which requires relaxed settings for ‘non-convex’ zone geometry (where not every surface has direct line of sight of every other surface).
Alternatively, in DesignBuilder v7.3 you can select the pixel counting method in Calculation Options. This leverages the GPU, significantly reducing simulation time for models with many shading surfaces. It also maximises accuracy through unrestricted use of the "Full Interior and Exterior" solar distribution option and avoids convexity constraints.
Our engineers tested pixel counting on a model with approximately 500 shading planes, and the results were remarkable:
- Allows the highest level of solar distribution accuracy for all zones.
- Simulation time dropped from 77 minutes to 7 minutes, that’s an 11-fold improvement.
- No need to remodel non-convex zones.
Note that the 2-Pixel counting method does not currently support semi-transparent shading surfaces. So this option should be avoided in models that have Standard component blocks with Maximum transmittance set to a value greater than 0.
More detailed information is available under the ‘shading calculation method’ in our Help article https://designbuilder.co.uk/helpv7.3/index.htm#Solar_Options.htm#Shading
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