Revit - Slab gap

I’m testing of Revit plugin. The Revit plugin seems to extract slab volume from rooms.
In my case I have a massive concrete slab so adding a plenum seems not an option for me.
Is there any way of exporting rooms with full f2f height?
So far I have tried:

  • hbjson - with Revit volume
    compute on and of
  • dfjson - with pull room height option on/off
    In all cases, rooms are modelled up to the slab. In dfjson case boundary conditions are adiabatic and in hb - external.

What I found kind of working is setting off room boundaries on floors but then it doesn’t solve adjacency correctly in Revit (solvable in RH later on).

Hi @blkkz,

We recently added the Manage Room Geometry button which makes it easy to set the rooms to go all the way to the floor above.

Or decide to offset share the space between the zones by changing Limit Offset and Base Offset. You will get the warning that you mentioned since the object is not bound to a room bounding element but you can ignore that in this case.

Our Revit plugin doesn’t do a great job of solving adjacencies yet. We made the decision not to spend too much time trying to resolve it since it is a quick step after importing the model to Rhino. Additionally, the models that are used only for daylight workflows won’t be affected by this workflow.

Thanks, Mostapha for pointing it out I didn’t know about this functionality. I will try it.
Yes, adjacencies aren’t a problem for me I still for through Rhino anyway. Since there are some places that need double-checking anyway.

This is actually an interesting topic is it actually good practice to use the same model for both simulations?
In EP+ model all spaces are modelled to wall centre and in my case floor 2 floor. So we don’t have real space geometry. To be accurate for Radiance sim we rather need internal geometry. Especially Ceiling height might have an impact on light bouncing across that room. So at the end of the day we need 2 models anyway?

BTW I thought since the new library is less Rhino dependent you are able to run the same routines. Therefore Revit add uses the same lib as Rhino.

In theory, this is correct but in practice, the difference will be much lower than you would imagine in most cases. It depends on how conservative you want to be in your assumptions. The most typical workflow is to add plenums between the zones to represent the slabs and the real plenum if any. That way the volume of the room/space/zone stays closer to the reality and the model is reusable for daylight simulation.

This is correct for all of the non-geometry aspects of the workflow. Intersections and solve-adjacencies are two of the functionalities that we are still dependent on the CAD geometry libraries. It can be decoupled and there are examples in OpenStudio that we can reuse but we decided against implementing it at this point for two main reasons:

  1. At this point, we want to focus on all the other aspects of cleaning the model and exporting a simulatable analytical model out of Revit. We also want to ensure all those functionalities are pretty stable.

  2. One can always use the Rhino plugin or other simulation tools to fix the solve adjacency after exporting the model from Revit.

Once we have that figured out we can get back to issues like implementing a better solve adjacencies functionality to Revit. In my mind, for the first version of the plugin, a successful Revit plugin should get you to 90-95% of an ideal model for an energy model and 95-100% for daylight models. That 5% in daylight modeling is for face-by-face materials and complex geometries which are not currently available in the Revit plugin.

Hope this helps and I would like to hear your thoughts. :slightly_smiling_face:

3 posts were split to a new topic: Apertures are moved vertically in extruded mode

We finally have a solution for this! Try version 2.74.3 which was released today. Here is how it works! :point_down:


This is great @mostapha … cant wait to install the latest version! (I am still waiting for the IT!!)

Does this plenum new feature create new zones on top of the selected level or it just pulls up the edges to bridge the gap?


Thanks! It pulls up the edges of the room upwards. This was the preferred option based on the feedback that we received!

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And that’s a great solution, really appreciate that … cheers