@lauri-luoma Thank you, yes, I make a lot of use of classifications, and also the duct dimensions from component properties (still, this may not always be available, and I’ve come across some unit problems even there).
However, being a heavy user of classifications in many aspects, I find building a classification for something so simple as Bounding Box dimensions overkill. The classifications also all require some processing time at model update, which gets multiplied when the HVAC models are split into separate IFCs per storey. The above rule itself processes this very quickly, when set up correctly, and only at the moment necessary for running the checking, which seems optimal…
But perhaps disabling classifications, or loading them automatically on demand, is something you are thinking about for future releases (I can of course manually unload/load these at the time of checking, but that again is unnecessary steps in the workflow).