Revit changes Unique ID


I have an HVAC Revit model where I have saved the unique id from elements in a parameter in my own electrical Revit model. This is used for coordination between models (place out elements, update location, parameters, and so on)

The problem occurred when I got a new version of the HVAC model and I could not match any of the previously unique ids…
I have talked with the HVAC designer and he told me that they have not deleted any elements, so it should not be new unique ids.

The HVAC model is saved by placing a 3D-view that shows the whole model, on to a sheet, and then deleting the sheet, right-click on it, and “save to new file”. Can it be this method that creates new unique ids?

I open both of the HVAC models to check if the unique id was wrong/different on the same element, and it was…

Does anyone have any suggestions on why this is happening?

Best regards

They might have created new elements because they have new Ids. Ask them if they use design options because if you change between options, Revit changes Ids and UniqueIds.

Yeah, I have asked them about it, but they are saying that they have not deleted elements…only added a few new ones.

It cannot even find one unique id from the previously HVAC model…and I find it strange if they are deleting 200 elements every week, just to place out the exact same ones…

Did you upgrade Revit version of model?

Nope, still the same version.

So I did a comperesend with my own Revit models, and it seems to be the method on how they save the Revit file. By doing the “move 3D-view to a sheet, right-click and save” that creates new unique id’s…I

If you look at these two elements, which are the same, but from two separate saved models (same model)

They have the same id in the last piece of the unique id. So it must be that I guess

I would use in that case GUID or ifcGUID because they are static. If element has not been changed.

Its the GUID that I have used here :slight_smile:

You are right but it is being generated because of

var uniqueGuID = System.Guid.NewGuid(); 

We use ifcGUID as parameter. They are not generated new.


Thank you for finding the answer Deniz! :slight_smile:

I will use ifcGUID for this work around!

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