Importing Industry Foundation Classes (IFC) Data

Introduction

Industry Foundation Classes (IFC) is an open and standardized data model developed by buildingSMART International for describing building and infrastructure information. It serves as the foundation of Building Information Modeling (BIM) interoperability, allowing different software applications to exchange 3D geometry and rich semantic data about building components, materials, and systems.

The IFC schema provides a neutral, object-oriented representation of physical and logical building elements, including walls, doors, beams, HVAC systems, fire safety components, and much more. Each element in an IFC file belongs to a well-defined class that specifies its role, attributes, and relationships to other entities.

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IFC Schema Overview

IFC defines a large hierarchy of entity classes, organized broadly into several conceptual layers:

Category	Description	Common Examples
IfcRoot	The base class for all IFC objects. Provides global ID, ownership, and name/description fields.	IfcProject, IfcSite, IfcBuilding, IfcElement
IfcProduct	Represents tangible, spatial, or physical elements in the built environment.	IfcWall, IfcBeam, IfcDoor, IfcSlab
IfcSpatialStructureElement	Defines the spatial hierarchy of a project (site → building → storey → space).	IfcBuilding, IfcBuildingStorey, IfcSpace
IfcElement	Represents individual building components.	IfcWall, IfcWindow, IfcColumn, IfcPipeSegment
IfcDistributionElement	Covers building services and MEP (Mechanical, Electrical, Plumbing) components.	IfcFlowSegment, IfcFlowTerminal, IfcFlowController
IfcMaterialDefinition	Defines materials, layers, or composites assigned to elements.	IfcMaterial, IfcMaterialLayerSet
IfcPropertySet	Attaches custom attributes and metadata to IFC elements.	Pset_WallCommon, Pset_DoorCommon
IfcRelationship	Describes connections and associations between objects.	IfcRelContainedInSpatialStructure, IfcRelDefinesByProperties

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IFC Import in FRI3D

FRI3D’s import system reads IFC files and maps their entities to internal simulation and visualization structures. This enables fire risk, smoke, and thermal analysis to operate directly on BIM data without manual re-modeling.

Import Workflow

1. Parsing: The IFC file is parsed using an IFC4x3-compatible reader.
2. Classification: Each entity is examined for its IFC class type and relevant property sets.
3. Tagging: Elements are tagged into FRI3D’s internal categories (e.g., FIRE_BARRIER, OPENING, EQUIPMENT, SPACE).
4. Geometry Extraction: Surface and solid geometries are read from IfcShapeRepresentation or simplified to bounding volumes for performance.
5. Metadata Mapping: Material and property data are retained to support simulation inputs (e.g., combustion properties, heat release rates, boundary conditions).

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Tagging Requirements

For accurate classification and simulation behavior, FRI3D requires that elements are appropriately tagged in the source BIM software (e.g., Revit, ArchiCAD, Tekla) before export.
This ensures that the IFC importer can identify fire-relevant elements correctly.

FRI3D Tag	Expected IFC Class	Example IFC Name	Purpose
FIRE_BARRIER	IfcWall, IfcSlab, IfcCovering	FireRatedWall_120min	Defines compartment boundaries and fire separation zones
OPENING	IfcDoor, IfcWindow, IfcOpeningElement	ExitDoor_Main	Defines openings for smoke flow and evacuation routes
EQUIPMENT	IfcFlowTerminal, IfcDistributionElement	SmokeDetector_01	Identifies active fire protection and HVAC elements
SPACE	IfcSpace	Room_102	Defines simulation zones or analysis volumes
STRUCTURE	IfcBeam, IfcColumn	SteelColumn_A12	Provides load-bearing and heat transfer geometry
FUEL	IfcFurnishingElement, IfcProxy	Cabinet_Wood	Used for fire load and combustible material definition

⚠️ Important:
FRI3D relies on these tags and IFC class mappings to automatically classify and group geometry during import.
Un-tagged or misclassified elements may be ignored or assigned default non-combustible behavior.

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Supported IFC Versions

FRI3D currently supports:

• IFC4 and IFC4x3 schemas (recommended)
• Partial backward compatibility with IFC2x3 for legacy datasets

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Step-by-Step Import Procedure

1. Prepare Your IFC File

Before importing into FRI3D, ensure your IFC file is properly prepared:

• Export from BIM Software: Use Revit, ArchiCAD, Tekla, or other IFC-compatible software
• Verify IFC Version: Export as IFC4 or IFC4x3 (recommended) for best compatibility
• Tag Elements: Ensure fire-relevant elements are properly tagged with appropriate IFC classes
• Check File Size: Large IFC files (>100MB) may require simplification or splitting

2. Import into FRI3D

1. Open FRI3D and navigate to the Store or Import menu
2. Select "Import CAD" or drag-and-drop your .ifc file
3. Wait for Parsing: FRI3D will parse the IFC file and display progress
4. Verify Geometry: Inspect the 3D view to ensure all elements imported correctly

3. Post-Import Verification

After import, verify the following:

• Spatial Structure: Check that building storeys and spaces are correctly identified
• Element Classification: Verify that walls, doors, and other elements are tagged correctly
• Material Properties: Review material assignments for fire simulation accuracy
• Geometry Quality: Ensure no missing or corrupted geometry

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File Format Details

IFC File Structure

IFC files are typically stored in STEP Physical File (SPF) format, which is a text-based representation:

Component	Description	Example
Header	File metadata, schema version, and project information	FILE_SCHEMA(('IFC4'));
Data Section	Entity definitions with unique IDs	#123= IfcWall(...);
References	Relationships between entities	#456= IfcRelContainedInSpatialStructure(...);

Common IFC File Extensions

• .ifc - Standard IFC file (text-based SPF format)

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Common Issues and Troubleshooting

Issue 1: Elements Not Classified Correctly

Symptom: Walls, doors, or other elements appear as generic geometry

Solution:

• Verify IFC class types in source BIM software (e.g., ensure walls are IfcWall, not IfcProxy)
• Check that elements have proper property sets assigned

Issue 2: Missing Geometry

Symptom: Some elements don't appear in the 3D view after import

Solution:

• Check that elements have valid IfcShapeRepresentation definitions
• Verify IFC export settings (ensure geometry is included, not just metadata)
• Try re-exporting from source software with different IFC export options

Issue 3: Coordinate System Mismatch

Symptom: Model appears in wrong location or orientation

Solution:

• Check IfcSite and IfcBuilding placement in IFC file
• Verify coordinate system settings in source BIM software
• Use FRI3D's coordinate transformation tools if needed

Issue 4: Performance Issues with Large Files

Symptom: Import is slow or FRI3D becomes unresponsive

Solution:

• Simplify geometry in source BIM software before export
• Split large models into multiple IFC files (by building or storey)
• Use IFC simplification tools or filters during export
• Consider using bounding box simplification for non-critical elements

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Best Practices

Before Export from BIM Software

1. Organize Your Model

   • Use consistent naming conventions
   • Group related elements logically
   • Remove unnecessary detail or temporary geometry

2. Tag Elements Properly

   • Assign correct IFC classes (avoid generic IfcProxy where possible)
   • Tag fire barriers with appropriate fire rating properties
   • Mark openings (doors, windows) clearly
   • Define spaces (IfcSpace) for each room or zone

3. Export Settings
   • Use IFC4 or IFC4x3 schema
   • Include geometry (not just metadata)
   • Export property sets (not just basic properties)
   • Consider file size vs. detail level

After Import into FRI3D

1. Review Classification

   • Check import log for warnings or errors
   • Verify element counts match expectations
   • Review spatial structure hierarchy

2. Validate Geometry

   • Inspect 3D view for missing or corrupted elements
   • Check for gaps or overlaps in fire barriers
   • Verify openings are correctly positioned

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Comparison with Other Import Formats

Format	Semantic Data	Geometry Quality	Fire Safety Data	Recommended Use
IFC	✅ Rich (BIM classes, properties, relationships)	✅ High (BREP solids, surfaces)	✅ Excellent (fire ratings, materials)	Primary choice for BIM-based fire analysis
STEP/IGES	⚠️ Limited (geometry only)	✅ High (BREP solids)	❌ None	Mechanical equipment, plant design
OBJ/glTF	❌ None (geometry only)	⚠️ Medium (meshes)	❌ None	Visualization, context models
Native CAD	⚠️ Varies	✅ High	⚠️ Varies	Direct CAD integration (if supported)

Recommendation: For fire safety analysis workflows, IFC is strongly recommended due to its rich semantic data and standardized fire safety properties.

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Citation

If you reference this material in publications or documentation, please cite as:

FRI3D Documentation: Industry Foundation Classes (IFC) Import and Classification Guide.
Centroid LAB, 2025.
https://centroidlab.com/fri3d/docs/

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What's Next?

After successfully importing your IFC model:

1. Configure Fire Scenarios - Set up fire sources, ignition points, and analysis parameters
2. Define Compartments - Verify and adjust fire compartment boundaries
3. Assign Materials - Review and refine material properties for accurate simulation
4. Run Analysis - Execute fire dynamics simulations using your imported model
5. Visualize Results - Analyze and visualize fire, smoke, and thermal results

For more information on other import formats, see:

• OBJ, glTF, and GLB Import
• STEP and IGES Import