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Can I ignore the Severe non-convex DetermineShadowingCombinations warning when using PixelCounting?

asked 2020-09-03 20:09:39 -0600

chriswmackey's avatar

updated 2020-09-16 17:17:52 -0600

I have been in love with the new GPU-based PixelCounting Shading Calculation Method that was added to EnergyPlus in version 9.3. It has brought about a Renaissance in my use of FullInteriorAndExteriorWithReflections for solar distribution.

I have noticed that using PixelCounting gets rid of the CHKBKS error noted in this issue. However, I still get the following warning when running certain types of models with PixelCounting:

** Severe ** DetermineShadowingCombinations: There are X surfaces which are casting surfaces and are non-convex

From the documentation in the EnergyPlus Input/Output reference that I linked to, it seems that using PixelCounting should eliminate the negative effects of this Severe error. So I was wondering if I can just ignore this error whenever I use PixelCounting.

If anyone wants to recreate the error that I am talking about, here is a sample IDF with PixelCounting that returns the Severe warning in the .err file:

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Also, I know that @Neal Kruis contributed this amazingly-helpful PixelCounting method and I thank him greatly for it. There will be A LOT of people in the Ladybug Tools community making use of it.

Neal, if you could just confirm that this is a bug, I'll silence this severe warning on the UI end of Ladybug Tools whenever PixelCounting is used. This should lessen the number of future posts here from Ladybug Tools users about this issue.

chriswmackey's avatar chriswmackey  ( 2020-09-06 11:53:48 -0600 )edit

@chriswmackey I'll look into it soon. Thanks for pointing this out!

Neal Kruis's avatar Neal Kruis  ( 2020-09-08 12:33:13 -0600 )edit

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answered 2020-09-08 16:00:00 -0600

updated 2020-09-08 16:17:59 -0600

Yes, you can ignore these severe errors.

The PixelCounting method tessellates all surfaces (convex, concave, and even those with windows) into many triangles (which are by definition convex), removing any limitations of non-convex (i.e., concave) surfaces from the shading algorithm.

I am working to remove these errors for PixelCounting in the next release of EnergyPlus at the end of the month.

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Wonderful! Thank you, Neal. The explanation makes sense and I will keep an eye on the EnergyPlus Github to see if you can work in the silencing of the errors before E+ 9.4. If you aren't able to get to it or we end up having a major release of the Ladybug Tools plugins before E+ 9.4, I'll add in some silencing on the Ladybug Tools end as I mentioned so we aren't getting extra posts about it here. Thanks again!

chriswmackey's avatar chriswmackey  ( 2020-09-08 20:54:19 -0600 )edit

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Asked: 2020-09-03 20:09:39 -0600

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Last updated: Sep 08 '20