Revit to IFC: An Export Guide - Part 9 - Classifications

Summary

The video explains how to assign Revit elements to classification systems and export those classifications to IFC. An IFC element can reference an external classification, allowing objects to be grouped or described according to a taxonomy.

Method 1: Export a classification with its source information

This method uses Revit parameters and the IFC export setup. The example uses Uniclass 2015.

1. Create and populate Revit parameters. The example uses custom project parameters for:
   • Building classification, stored with Project Information
   • Room or space classification
   • System classifications for elements such as walls, floors, and roofs
   • Product classifications for individual objects such as furniture and fixtures

Parameters are applied at the appropriate level, such as type level for the example’s products and systems.

1. Enter each classification using the required syntax:
   • Classification code
   • A space, semicolon, and a space
   • Human-readable classification name

The code identifies the classification item, and the text after the semicolon describes it.

1. Configure the IFC export.
   • Open the IFC export settings and go to the property-set and classification settings.
   • Enter the classification system name, publisher or source, edition information, and documentation URL.
   • Specify which Revit parameter contains the classification value for each relevant object kind, such as building/entity, space, system, or product.
   • Separate parameter names with a comma and a space where needed.

The exporter configuration allows only one parameter per object.

1. Export and verify. In an IFC viewer, the classification appears as a reference. The code and description are split into identification and name attributes, and the URL and source information are also available.

Method 2: Export additional classifications without source metadata

If another classification system is not configured in the IFC exporter, it cannot be exported with the same associated classification-source information. Revit’s shared parameters can still export additional classification references.

1. Add Revit’s shared Classification Code parameters as project parameters and apply them to the relevant categories.
2. Enter the code and description using the same code ; name syntax.
3. To identify the classification system, prepend its name in square brackets, followed by a space. The video demonstrates this with NRM1.
4. Use another classification-code parameter for a separate system, such as a client-specific coding scheme. In that example, the system name is written before the code and description.
5. Re-export the IFC and inspect the element. The viewer can show multiple classification references: the exporter-configured Uniclass reference and the additional references supplied through the Classification Code parameters.

These additional references can include the classification name, code, and description, but not the source or edition information available through the exporter-configured method.

Instance versus type parameters

Classification Code parameters can be type- or instance-based. Use an instance parameter when classifications need to vary from one element to another. If the desired instance parameter is unavailable, the video says to add another numbered Classification Code parameter as an instance parameter.

Speakers and sources featured

• Speaker: One unnamed narrator or presenter; no other speakers are identifiable in the subtitles.
• Classification systems or schemes discussed: Uniclass 2015, NRM1, and an example client-specific classification.
• Other named sources or tools: NBS is identified as the Uniclass source or publisher in the example. Revit, IFC, and an IFC viewer are used or discussed.