Downgrade IDF 9.x to 7.x: Viewfactor calculation using Radiance eplus_adduvf.exe

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In EnergyPlus v9.0, there was a change made to remove the "Shading Control Name" input field from the FenestrationSurface:Detailed object used to define windows. That shifts input fields "up" by one from previous versions, so the error is likely because it's trying to read an integer for "Number of Vertices", but instead it's reading a float or real value for the X-coordinate of the first vertex instead.

Below is a window defined in the EnergyPlus example file WindowTests.idf before and after v9.0:

Fenestration before v9.0

  FenestrationSurface:Detailed,
    Zn001:Wall001:Win001,    !- Name
    Window,                  !- Surface Type
    SINGLE PANE HW WINDOW,   !- Construction Name
    Zn001:Wall001,           !- Building Surface Name
    ,                        !- Outside Boundary Condition Object
    0.5000000,               !- View Factor to Ground
    ,                        !- Shading Control Name ***INPUT FIELD THAT WAS REMOVED***
    ,                        !- Frame and Divider Name
    1.0,                     !- Multiplier
    Autocalculate,           !- Number of Vertices
    0.200000,0.000000,9.900000,  !- X,Y,Z ==> Vertex 1 {m}
    0.200000,0.000000,0.1000000,  !- X,Y,Z ==> Vertex 2 {m}
    9.900000,0.000000,0.1000000,  !- X,Y,Z ==> Vertex 3 {m}
    9.900000,0.000000,9.900000;  !- X,Y,Z ==> Vertex 4 {m}

Fenestration after v9.0

  FenestrationSurface:Detailed,
    Zn001:Wall001:Win001,    !- Name
    Window,                  !- Surface Type
    SINGLE PANE HW WINDOW,   !- Construction Name
    Zn001:Wall001,           !- Building Surface Name
    ,                        !- Outside Boundary Condition Object
    0.5000000,               !- View Factor to Ground
    ,                        !- Frame and Divider Name
    1.0,                     !- Multiplier
    Autocalculate,           !- Number of Vertices
    0.200000,0.000000,9.900000,  !- X,Y,Z ==> Vertex 1 {m}
    0.200000,0.000000,0.1000000,  !- X,Y,Z ==> Vertex 2 {m}
    9.900000,0.000000,0.1000000,  !- X,Y,Z ==> Vertex 3 {m}
    9.900000,0.000000,9.900000;  !- X,Y,Z ==> Vertex 4 {m}

If this adduvf.exe tool in Radiance can read the EnergyPlus version for the IDF it's reading geometry from, then you can include an if/else check to alter the input field numbers accordingly ("Number of Vertices" is input #10 before v9.0 and input #9 after v9.0, e.g.). That seems much easier than figuring out a way to "downgrade" an IDF to an older version of EnergyPlus. I'm not aware of tools that can do that for you.