Enable ZoneProperty:UserViewFactors:bySurfaceName

asked 2020-01-27 14:37:51 -0600

rafael.alonso
933 ●1 ●6 ●12 http://atmoslab.io

updated 2020-01-28 03:12:27 -0600

Julien Marrec

29726 ●94 ●76 http://www.effibem.com/

Hello,

I´m working to get the ZoneProperty:UserViewFactors:bySurfaceName to work on a test file.

So far, with the great help from Radiance developers we have found a way to automate the writing of these viewfactors. However, once written, the simulation Succeeds but tje test file keeps throwing the same severes in eplusout.err as before

 ** Severe  ** Problem in interior solar distribution calculation (CHKBKS)
 **   ~~~   **    Solar Distribution = FullInteriorExterior will not work in Zone=ZONE_6
 **   ~~~   **    because vertex 1 of back surface=ZONE_6_SRF_8 is in front of receiving surface=ZONE_6_SRF_10
 **   ~~~   **    (Dot Product indicator=30.6234)
 **   ~~~   **    Check surface geometry; if OK, use Solar Distribution = FullExterior instead.
 ** Severe  ** Problem in interior solar distribution calculation (CHKBKS)
 **   ~~~   **    Solar Distribution = FullInteriorExterior will not work in Zone=ZONE_6
 **   ~~~   **    because vertex 2 of back surface=ZONE_6_SRF_8 is in front of receiving surface=ZONE_6_SRF_10
 **   ~~~   **    (Dot Product indicator=24.7603)
 **   ~~~   **    Check surface geometry; if OK, use Solar Distribution = FullExterior instead.
[...]

Is there any specific field in the idf where I need to enable the use of these ZoneProperty:UserViewFactors:bySurfaceName?

The files are here: original model and viewfactor model.

Thanks, Rafael

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Comments

You are probably aware, but others might not: ZonePropertyUserViewFactorsBySurfaceName was added recently to OpenStudio.

I ran your view factor file in EnergyPlus 9.2. The error message your posted is (very truncated)... Missing some helpful information, I'll edit your post

Julien Marrec ( 2020-01-28 03:10:40 -0600 )edit

Have your thoroughly checked your geometry to see what's going one with the specific vertices it's mentioning?

Julien Marrec ( 2020-01-28 03:13:07 -0600 )edit

I was not aware of that implementation in OS - seems very useful.

Initially, I had thought that adding the ViewFactors would just overcome this type of errors, so I didn´t really dive deeper into each of them. I found it strange that the same file with/without the Viewfactors would show exactly the same errors. I´ll check them more thoroughly once I get the chance.

PS thanks for amending the post and the additional clarity.

rafael.alonso ( 2020-01-28 03:45:30 -0600 )edit

(to be clear: OpenStudio now supports adding custom view factors via the model API, not calculating them).

Julien Marrec ( 2020-01-28 06:54:26 -0600 )edit

SolarShading::CHKBKS is called when solarDistribution is FullInteriorExterior (hence why it tells you that can switch to FullExterior), regardless or whether you enter view factors. This a Solar Shading thing, while the ZoneProperty:UserViewFactors:bySurfaceName is about Heat Balance / internal radiation exchange.

cf https://github.com/NREL/EnergyPlus/bl...

Julien Marrec ( 2020-01-28 06:58:11 -0600 )edit

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answered 2020-01-29 01:38:31 -0600

janak
21 ●2

I think that "Solar Distribution = FullInteriorExterior" will work only in simple rectangular thermal zone geometry. So for example this error will show in L-shaped zone geometry.

Have a look at InputOutput E+ manual

1.4.4.1.7 Field: Solar Distribution

"You should also be sure that the zone is convex. Examples of convex and nonconvex zones are shown in Figure 1.2. The most common non-convex zone is an L-shaped zone. (A formal definition of convex is that any straight line passing through the zone intercepts at most two surfaces.) If the zone’s surfaces do not enclose a space or if the zone is not convex you should use Solar Distribution = FullExterior instead of FullInteriorAndExterior."

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Comments

Hi Janak,

thanks for this. I´m aware of the limitations with Solar Distribution = FullInteriorExterior but somehow, I thought it could be overcome by the User defined view factors.

The more I think about it the more I´m realising this might not be the case, but I keep wondering what´s the way forward to have E+ assign the right incident solar radiation to internal surfaces in non-convex zones.

rafael.alonso ( 2020-01-30 06:10:22 -0600 )edit

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