Revit- Backward compatible? Yes to a point via IFC

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I can’t actually recollect who had told me that you could go backwards in Revit versions by exporting to IFC and then opening a new project and bringing in the IFC into a previous version. I know Matt Cantwell was doing quite a lot of work with bringing information in from IFC’s but not the step from an original Revit Model.

You hear something said, but you have to give it a try. So here goes.

Export from Rvt 2019 to IFC

So I started off with a model in Revit 2019. And exported it to 2×3 Coordination setup to  IFC . I was in New Construction, show complete as the phase setup.

The file is about 89.5Mb with two linked files, the seating and the structure.  It exported to IFC quite quickly, as in 1-3 minutes. The file size for the IFC export is 59MB. A bit smaller than the original RVT file

Import to Rvt 2018 from IFC

To import it into an earlier version of Revit, in this instance Revit 2018, you open a new project then click on open and click on IFC. Below that selection is a setup box for IFC import for adjustments.

Importing takes an age, as in more than an hour, even a couple of hours (This particular model took 60 minutes). It just potters along and does its own thing.  The best thing to do is to open a couple of instances of Revit, set one up importing the IFC and carry on working in the other instance of revit.

I was working on a project with the main model in Archicad and a Revit model with little bits in the office & the Structural model in Revit. All a bit messy. They had linked the ArchiCad IFC and the Structural model into the vague Revit model in the office. Since all the datums etc were in the IFC file I found it frustrating working through links. In the end I imported the IFC into a new Revit Model, brought in the Structural as a link and did the HVAC in Revit and it was fine. It took a while to set-up and import the IFC but after that the workflow went very smoothly.

I did one import into 2018 and saved it, my PC was getting a bit vague so I rebooted it. When I tried to open the file it said Invalid Schema. So I am redoing the IFC import. i will do a couple of purges and do a couple of saves, (Also open a 2nd instance of 2018 and try and open one of the saves before closing out the IFC import file again.

When Revit finally responded I got:

And the model looks like this:

  • No links came across
  • Topography contours have been simplified
  • Odd orange boxes around windows
  • Odd line between rooves.

Phases all over the place, now there are:

  • Existing
  • Demo
  • Phase 1
  • Phase 2
  • Phase 3

Note, these can be COMBINED  with PREVIOUS /NEW Phases , so can get back the old naming of the phases again. You would still need to moves stuff back to Existing/Demo as pretty much everything in on Phase 3

In plans the phases seemed to have merged and data from different phases is all on the same plan.

Also the families seem to mainly have changed to “Generic Model’ or modeled in place (Railings). So these may need to be built again if you intend to change them.

The shared parameters and all their data seem to have disappeared. Some of the inBuilt Parameter stuff is still there, eg wall area etc.

No Rooms/Spaces. These would need to be created again.

After the file is imported, the save size is 125MB. A bit bigger than the original at 89.5Mb and the IFC at 59Mb.  Purging doesn’t seem to have done much as far as file size goes.

Basically, after importing you get a model with the main walls/floors as wall/floor categories, windows, doors as win/door category and a lot of generic model families all in the Current (New phase of the project). I suppose you could save the existing phase as a seperate IFC and then ONLY the New Items in the New Phase as a separate IFC so you could combine the two to get a proper phased model.

Note: Handy tip.

If you have a linked file in a model, and you want to do some adjustments in the linked file, open another instance of Revit (same version). If you try and open up the linked file in the single version of revit it will delink from your model. Whereas if you do updates in the 2nd instance and save it, just go to your initial instance in Revit and update the link.

Import to Rvt 2015 from IFC

Not a show from Rvt 2019 export. It just wouldn’t do it. I also tried linking the IFC instead of bringing it in to Revit.

I then tried some of the other versions, such as 2×2 coordination IFC but that didn’t work either.

I suppose you have to do it in incremental steps, say 2 versions of Revit backwards at a time.

End comment

If you did open a model in a later version and wanted to retrieve it for an earlier version you are able to, but not with much embodied Information. It great for basic geometry.

It s like an old as-built plan, you have data from elsewhere, not in the format you need, but it is a base point, better than starting from the very beginning.

Its good to have done the exercise, handy to know its potential. But I’d only do it if I had to. There is still a lot of work to bring it up to a fully functioning model.

If on the other hand you you just need the building for doing a minor alteration, this is a great solution, as you can push everything back to EXISTING PHASE and just add a NEW PHASE for your small changes.

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