Juan, your question is interesting and opens wider perspectives than just this subject, especially such questions as “which kinds of artefacts are necessary for engineering and architecture design ? Which models contribute and how ? How are artefacts spread among those models ?”
In order to address this volume constraint correctly, you have (as for most engineering concerns):
first to capture related requirements (let us say in Doors)
then to find the appropriate representation(s) - possibly models - that will help you, not only to formalise or document this constraint, but also to design the solution and check it against this constraint
and to relate both to each other.
Arcadia and Capella are approriate for capturing [operational, functional and associated non-functional] need, and define a solution based on component breakdown, functional contents and behaviour allocation, conceptual interface definition, and check of related properties/constraints. This is very well adapted at least to initial, high level architecture analysis, design and sharing. You can usually go up to the detailled synopsis you usually draw. But to go further up to detailled design and realisation, you usually change your representations, adding 3D views, or wiring/routing representations, …
Similarly, for component volume, geometry, form factor… considerations, Arcadia and Capella are probably not appropriate, when compared to a 3D CAD tool. So my vision would be to use them for the former purpose, but to switch to your favorite CAD authoring tool to address geometry issues.
So in Capella model you will have traceability links between requirements and the relevant component (submitted to these constraints), described in terms of functional contents, interface and behaviour;
this component in Capella could be linked (by your own workbench, PLM or so) to the corresponding component in your CAD tool, for navigation/impact analysis purpose;
in the CAD tool, the room will be modelled, and that CAD component as well; the CAD tool will allow taking into account the geometry issues;
Here and only here in CAD tool you will be able to check that your design meets the volume and room requirements; so this is where the romm needs to appear;
the initial requirement should be linked to this CAD component as wellas to the Capella component, or even instead.
Just to summarise: The Arcadia/Capella model will be your “entry portal” and “touring/navigation map” to browse and exploit your engineering data and assets, while mastering complexity. But it is not intended to carry the whole of them.
Don’t try to put all your engineering assets inside the Capella model, but rather focus on what you will be able to check and justify with it - and choose another
complementary tool when and where it is more relevant.