Floor area of air control vents

I would like the ‘floor area’ displayed in the ‘field’ of the air control vent tally table to reflect the floor area of the room (space) in which I have placed it.

Hello @YOSHIKATSU_MATSUURA and welcome…could you show your graph ?

Sorry for the late reply, I am still new to Dynamo work and do not know what to do in such cases. Sorry, I’m still new to Dynamo work and don’t know what to do in such cases.

No worries…just share a screenshot with you graph extended