Are you sure your building is working without the child surfaces? I have checked and confirmed my suspicion, that the errors are originating from incomplete splitting occurring at the IntersectMasses component, (on my computer using Rhino 6, latest GH, latest HB, OpenStudio 2.5). Furthermore eliminating child surfaces isn’t doing anything on my end.
Here’s an example of an error:
That refers to the surface intersection for these two building elements:
Leaving aside that this isn’t the correct way to model a subset of rooms within a larger building, here’s how the IntersectMasses component splits the surface of the larger volume in your current GH model:
As you can see the surface of the larger volume is not split. Thus the interzone surfaces are not the same size and won’t satisfy the conservation of energy during the simulation process. Hence your errors. I’m not surprised you’d have additional errors when adding child surfaces, but you need to address your upstream issues first before tackling them.
That being said, I think the larger problem here is that you have an unnecessarily complex model. I assume you are attempting to assess the natural ventilation of the some apartment units at the top of your building? You shouldn’t be adding these gigantic thermal zones with no windows, to representing large sections of your building. Just represent the apartment units in isolation, and use an adiabatic surface to define the bottom floor. If you need to account for the whole building energy, you can model some more representative zones and use the zone multipliers option in HB to represent a larger mass.
That way, you don’t even need to use the IntersectMasses component to split the bottom of these surfaces, thereby avoiding this problem in the first place. So I would encourage you to first simplify this model, before continuing to debug this model.