[EnergyPlus_Support] effective similarity of "ventilated slab" when compared with a "massive plenum"

["S." <canukcanoehead@xxxxxxxx>]

I am a relative newbie that is trying EP and Design Builder to model a masonry building that uses hollow core concrete slab roofs as an air distribution/storage/radiant heat system.

Design Builder to my knowledge does not currently have the EP ventilated slab system, but does have plenums.  I am hoping that by defining a plenum by using concrete for the ceiling and the roof material that I can approximate the performance of a ventilated slab.

so, the questions are:

1)  is this adaption reasonable?  (some feedback has supported the idea)

2)  are any of the thermal transfer coefficients methodologies that are buried in the ventilated slab model published so that I may use them in modifying default plenum coefficients etc?  otherwise I may have to  model a known building (with logged temperatures and energy use) to recursively guestimate suitable coefficients. (lots of work, and not really verifiable for LEED)

3)  is there any description of the measures used to create the ventilated slab model available, in case the general logic can be used to form or validate the plenmum setup?

4) would it be feasible, as an alternate, to produce a model in DB using a simple system, and then swap out the simple system with ventilated slab data?  (a one way street, can't go back into DB for edits)

thank you

Stephen H.



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