I have modelled a simple IfcWall with an IfcOpeningElement with BlenderBIM (version BlenderBIM 0.0.220221) and exported it to IFC.
I measured the NetSideArea of this particular wall in BIMVision
Going to BlenderBIM to measure and validate it, it's correct.
Now my aim is to assign this property to BaseQuantities. using this tool.
So far, it's correct:
Definition of NetSideArea from BuildingSmart :
Area of the wall as viewed by an elevation view of the middle plane. It does take into account all wall modifications (such as openings). The exact definition and calculation rules depend on the method of measurement used.
The next step is to add an IfcOpeningElement and see if the measurement is still correct.
I added an opening like this.
Exported it to IFC again and measured it with BIMvision. As you can see it's now 25,4m^2
Now I removed the Qt_WallBaseQuantities in BlenderBIM and it still calculates 29m^2.
I thought maybe if I closed Blender and import the IFC again it will work. As shown here, the IfcOpeningElement is now hidden.
It still calculates 29m^2 for NetSideArea despite the IfcOpeningElement
Also when I go to Edit Mode in Viewport Overlay, because Imported it again, the surface of the mesh got triangaluated.
I used Dissolve Faces to get to the measurement, which is then correct
My question is, is there a possible way the NetSideArea of an IfcWall will calculate the correct quantity? Which then can be added to Qto_WallBaseQuantities. It seems like very complex task to calculate the surface of each mesh of an IfcWall correct with IfcOpeningElements, but not undoable. It would be a very useful feature.