Thursday, July 5, 2018

Revit 'Energy Settings' Tip - Avoid Masses Only Setting

I wrote a post a while back about Autodesk's work with gbXML.org on Level 3 Certification and Validation. That post talks about Revit's ability to create a more accurate energy model automatically. This new workflow supplants the previous method which resulted in special mass elements, in some cases, required rooms/spaces to be created. This post highlights the fact that the old  way is still in Revit for legacy reasons, but should be avoided to leverage the latest and greatest features in this area.

First, there is what Revit help says on the topic...

  • Use energy settings: This method exports the energy analytical model created by Revit.
    The energy analytical model is composed of analytical spaces and analytical surfaces, which are created based on parameters defined in the Energy Settings dialog. The exported data provides an accurate energy model for analysis. Before using this method, define parameters in the Energy Settings dialog and create an energy analytical model.
  • Use room/space volumes: This method uses volumes defined in the building model based on rooms or spaces in the model. These volumes may not be as accurate as those created using energy settings. Before using this method, add rooms or spaces to the model.
    The resulting gbXML file contains energy information for the model according to the gbXML file structure, which is based on a gbXML schema. The gbXML schema was created to help building designers get information about the energy consumption characteristics of their building projects. For more information about the gbXML schema, visit http://www.gbxml.org.

Next, I will quickly show the two methods and the resultant energy model in Revit.


The New Way...

In Revit's Energy Settings dialog, select either Use Conceptual Masses and Building Elements or Building Elements.


Now, when an energy model is created in Revit, the result is analytical surfaces and spaces with thermal zoning as showing in the next two images.



All of the analytical elements are controlled via the Visibility/Graphics Overrides dialog.


The Old Way...

In Revit's Energy Settings dialog, select Use Conceptual Masses.


The result in Revit, after creating an energy model, is a special type of mass element which contains extended data as shown here.


The visibility of these special mass elements is controlled from the Masses & Site tab as shown here. FYI: With the new workflow, these second two mass visibility options are never used.


Exporting gbXML files directly from Revit

Related to all of this is the export to gbXML option from Revit. This may be a little confusing, but the "new way" is represented by the Use Energy Settings option, and the "old way" by Use Room/Space Volumes.


I have seen MEP firms with a refined workflow using the 'old way' to get into Trane Trace 600, and that is fine.  But for Autodesk's Revit + Insight workflow and to leverage the newer, more accurate gbXML export you will want to use the "new way."

Fun stuff...


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