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What are the causes and implications of the warning "Too many figures [>15000] in a shadow overlap"?

asked 2017-11-08 16:46:41 -0500

Molly Curtz's avatar

updated 2017-11-08 17:52:04 -0500

When this warning occurs, what is the result in the simulation? Is shading ignored for that timestep?

As advised in the warning message, I've used Output:Diagnositcs "DisplayExtraWarnings" to get additional information. An example of what that produced is here:

** Warning ** Too many figures [>=15000] in a shadow overlap
**   ~~~   ** Overlapping figure=Mir-POLYGON 2 OF BUILDING 1 - SHADING PLANE 55, Surface Class=[Detached 
 **   ~~~   **   This error occurred 1 times.
 **   ~~~   ** Figure being Overlapped=CIRCULATION10.1:CIRCULATION10.1_EXTFLOOR_1_10_0, Surface Class=[Floor]

And, I did read the related post here, which gives some ideas on how to reduce the likelyhood of this warning occurance.

Is this warning occurrence only related to large number of shading surfaces, or is it also more likely to occur with large number of building surfaces?

I have some ideas on how to reduce the Shading:Building:Detailed surfaces (currently ~150 in my model), but it would be difficult to reduce the BuildingSurface:Detailed surfaces (currently ~4100 in my model).

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answered 2017-11-09 11:00:03 -0500

Molly Curtz's avatar

Googling, I found this information from @MJWitte in the EnergyPlus Knowledgebase.

But, it doesn't answer my questions of what happens in the simulation when this error/warning occurs, and whether it is more likely to occur with many building surfaces.

"It may be safe to ignore these warnings, but it is hard to know for sure." is not very satisfactory! :-)

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I could be wring, but it is possible it won't do any calculations beyond that 15k which means you may not have accurate shadow calculations. I would start with item 2 from Mike's answer, if you don't have shading surfaces that need to be two sided, and if that doesn't get you below 15k, then go with item 1 to increase capacity.

David Goldwasser's avatar David Goldwasser  ( 2017-11-09 11:21:20 -0500 )edit

@David Goldwasser: thanks for your input!

Molly Curtz's avatar Molly Curtz  ( 2017-11-09 13:08:56 -0500 )edit

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Asked: 2017-11-08 16:46:41 -0500

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Last updated: Nov 09 '17