When modelling a plenum using Energy PLus, there are too way to model a plenum, as I understood it. The first way is to model a separate zone that will be the plenum. The second is to model the plenum as an air layer in the ceiling or floor construction.
This post on unmet hours explains it pretty good : https://unmethours.com/question/4171/how-to-modeling-the-ceiling-void/
For many reasons, the first option, which in Honeybee would require to use the HB plenum zone component, is not convinient for my parametric model.
I think it could be modelled in Honeybee with the second option, i.e. adding a layer of air in the construction. Maybe the F05 CEILLING AIR SPACE RESISTANCE material that is in the EP library ? It has a U value of 5.55 which is good to represent an unventilated horizontal air cavity (similar U values in design builder for such elements).
Has anyone ever done this in Honeybee ?