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# Base Surface Name for Shading surface is wrong in IDF exported

I found that the "Base Surface Name" for a Shading:Zone:Detailed object is not correct in the IDF exported from OpenStudio.

Examples is shown blew in which the two shading surfaces belonging to different base surfaces have the same base surface name.

Can the OpenStudio team kindly check and advise on this problem? Thanks!

This is important since I need to refer to the Base Surface Name to get the thermal zone and its origin so that it can be added to the shading surface vertices coordinates to recreate the surface in other software ...

Shading:Zone:Detailed,
Sub Surface 3 - Overhang,               !- Name
Surface 2,                              !- Base Surface Name
,                                       !- Transmittance Schedule Name
,                                       !- Number of Vertices
4.9746, -0.606158571082195, 1.97231714216439, !- X,Y,Z Vertex 1 {m}
4.9746, 0, 1.97231714216439,            !- X,Y,Z Vertex 2 {m}
0.0254, 0, 1.97231714216439,            !- X,Y,Z Vertex 3 {m}
0.0254, -0.606158571082195, 1.97231714216439; !- X,Y,Z Vertex 4 {m}

Sub Surface 6 - Overhang,               !- Name
Surface 2,                              !- Base Surface Name
,                                       !- Transmittance Schedule Name
,                                       !- Number of Vertices
5.60615857108219, 0.0254, 1.97231714216439, !- X,Y,Z Vertex 1 {m}
5.60615857108219, 4.9746, 1.97231714216439, !- X,Y,Z Vertex 2 {m}
5, 4.9746, 1.97231714216439,            !- X,Y,Z Vertex 3 {m}
5, 0.0254, 1.97231714216439;            !- X,Y,Z Vertex 4 {m}

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This is a valid issue, I've filed this bug in the OpenStudio issue tracker . In the meantime, you can use an EnergyPlus measure as @David Goldwasser suggests.

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Currently the shading surface in OpenStudio doesn't have a field to store the base surface.

The overhang user script and measure do name the surface after the subsurface object it is made above. You can use an Energy Plus measure add the additional data.

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1

@David Goldwasser, the shading surface group does have a field to point to either a surface or subsurface. Unfortunately it is not being used in translation to IDF.

( 2015-03-14 15:01:34 -0600 )edit

Thanks @macumber, I wasn't aware of that.

( 2015-03-14 15:08:40 -0600 )edit

Dear David, what is the EnergyPlus measure you mentioned to add the additional data? I found that only the shading surface added by using "add overhang by projection factor" script has the "base surface name" field in the IDF exported. Otherwise, there is no such field at all. May I ask that in the latter case if the coordinates of the vertices of a shading surface are the absolute world coordinates or coordinates relative to certain zone origin? Thanks!

( 2015-03-25 09:17:08 -0600 )edit

So, what's the conclusion here?

( 2015-04-17 09:37:57 -0600 )edit
1

We need to respect the field if it is set and use a better algorithm to pick it if it is not set, that is all captured in this bug. So you should give the bug report a '+1' and hopefully it will get fixed soon :-)

( 2015-04-17 10:19:32 -0600 )edit