The iModel Digital Completeness Index: Revit & IFC Modeling Guide

Core Principle: Data quality, accuracy, and absolute trust are C&C Solutions' primary Unique Selling Proposition. Automated rules can only validate what is modeled. If an element lacks spatial boundaries or property sets, the audit cannot return a definitive pass or fail and flags Insufficient Information.

The iModel Digital Completeness Index ($I_{\text{comp}}$) is a quantitative metric from 0.00 to 1.00 that evaluates whether an iModel possesses the geometric and semantic integrity required for automated statutory compliance audits.

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1. The Four Pillars of iModel Completeness

Pillar 1: Spatial Structure & Storey Containment (25%)

• Every physical element (doors, walls, beams, ducts) must be spatially contained within an active Storey (bis.InformationPartitionElement).
• Zero unbound or floating room polygons. All rooms must have closed boundary loops formed by boundary walls or room separation lines.

Pillar 2: 3D Geometric Representation & Bounding Boxes (25%)

• Every element must possess a physical 3D volumetric representation. Never emit ghost physical elements with null geometry (Representation = $).
• Bounding boxes (BBoxLow, BBoxHigh) must represent real positive bounding intervals ($\Delta x > 0$, $\Delta y > 0$, $\Delta z > 0$).
• Element origins must reflect real project coordinates; never corrupt the iTwin Viewer base map with artificial or conflicting project base point coordinates.

Pillar 3: Semantic Parameters & Standard Property Sets (30%)

• Parameters must be populated using statutory naming standards:
  • Fire ratings must be concrete token strings (EI 60, FD60S, REI 120), not ambiguous catalog options (20 min, 45 min, 60 min).
  • Door openings must provide nominal Width, frame stop dimensions, and leaf thickness.
  • Room spaces must contain exported base quantities (Qto_SpaceBaseQuantities.GrossFloorArea and NetFloorArea).

Pillar 4: Multi-Discipline Federation Integrity (20%)

• Healthcare audits require cross-discipline coordination. The iModel must federate all required discipline models:
  1. WRSH_Architectural.ifc (Rooms, doors, partitions, stairs)
  2. WRSH_Structural.ifc (Columns, framing beams, concrete slabs)
  3. WRSH_Mechanical.ifc (Supply/extract HVAC ducts, air handling units)
  4. WRSH_Plumbing.ifc (Drainage, sanitary fixtures, water supply)
  5. WRSH_Electrical.ifc (Cable trays, main switchboards)

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2. Comprehensive Revit & IFC Data Mapping Matrix

Building Component	Revit Category	IFC4 / IFC2x3 Entity	Bentley BIS Class	Required Properties / Psets	Evaluated Statutory Rules
Enclosed Rooms & Wards	OST_Rooms	IfcSpace	SpatialComposition.SpatialElement / bis.SpatialLocationElement	Name, Area, Qto_SpaceBaseQuantities.GrossFloorArea, NetFloorArea	HOSP-PLN-001, HOSP-PLN-002, HOSP-PLN-003, HOSP-EVAC-003
Corridors & Circulation	OST_Rooms	IfcSpace	SpatialComposition.SpatialElement	Name containing Corridor, Circulation, Passage, Hallway	HOSP-EVAC-002, HOSP-EVAC-003
Clinical Doors	OST_Doors	IfcDoor	bis.PhysicalElement / bis.GeometricElement3d	Width, Frame Width, Thickness, Pset_DoorCommon.ClearWidth, Pset_DoorCommon.FireRating, Pset_DoorCommon.IsExternal	HOSP-EVAC-001, HOSP-FIRE-001, HOSP-EVAC-003
Fire Partition Walls	OST_Walls	IfcWall / IfcWallStandardCase	bis.GeometricElement3d	Fire Rating, Top Constraint, Unconnected Height, Pset_WallCommon.FireRating	HOSP-FIRE-001, HOSP-FIRE-002, HOSP-EVAC-003
Structural Downstand Beams	OST_StructuralFraming	IfcBeam / IfcMember	bis.GeometricElement3d	Level, BBoxLow.z (Bottom elevation of beam solid)	HOSP-CLR-001
Structural Columns	OST_StructuralColumns	IfcColumn	bis.GeometricElement3d	BBoxLow, BBoxHigh, 3D encroachment footprint	HOSP-EVAC-002, HOSP-EVAC-004
Railings & Handrails	OST_Railings	IfcRailing	bis.GeometricElement3d	BBoxLow, BBoxHigh, Corridor obstacle geometry	HOSP-EVAC-002 (Excluded from HOSP-EVAC-004)
Overhead HVAC Ducts	OST_DuctCurves	IfcDuctSegment / IfcFlowSegment	bis.GeometricElement3d	Level, BBoxLow.z (Bottom elevation of duct solid)	HOSP-CLR-002
Stair Flights	OST_Stairs	IfcStairFlight	bis.GeometricElement3d	Actual Run Width, Riser Height, Tread Depth, BBoxLow, BBoxHigh	HOSP-EVAC-004, HOSP-EVAC-003
Accessibility Ramps	OST_Ramps	IfcRampFlight / IfcRamp	bis.GeometricElement3d	Slope, Length, Level landing elevations	HOSP-ACC-001
Accessible Sanitary Rooms	OST_Rooms	IfcSpace	bis.SpatialLocationElement	Name (WC, Toilet, Shower, Sanitary), 2D bounded footprint polygon	HOSP-ACC-002 (Inscribed 1.50m circle)

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3. Recommended Revit Export Settings for iTwin Synchronization

To ensure your Revit models achieve a 1.00 Digital Completeness Index upon bridge ingestion into Bentley iTwin:

Essential Revit IFC Export Options:

1. IFC Version: Select IFC4 Reference View [Architectural] or IFC2x3 Coordination View 2.0.
2. Space Boundaries: Set to Level 2 (calculates exact thermal and spatial boundaries between rooms and walls).
3. Base Quantities: Check Export base quantities (generates Qto_SpaceBaseQuantities, Qto_WallBaseQuantities, etc.).
4. Storey Splitting: Check Split walls and columns by story (ensures multi-storey shafts do not corrupt single-level headroom calculations).
5. Property Sets: Check Export Revit property sets and Export IFC common property sets.

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4. Pre-Flight Diagnostic Suite (Property Analysis Console)

Engineers can paste these 4 pre-flight queries directly into BIM Checker's Property Analysis query console to evaluate model readiness:

Diagnostic 1: Spatial Room Readiness & Base Quantities Check

SELECT 
  COUNT(sp.ECInstanceId) AS totalSpaces,
  SUM(CASE WHEN q.GrossFloorArea IS NOT NULL THEN 1 ELSE 0 END) AS spacesWithGrossArea,
  SUM(CASE WHEN q.NetFloorArea IS NOT NULL THEN 1 ELSE 0 END) AS spacesWithNetArea
FROM bis.SpatialLocationElement sp
LEFT JOIN IFCDynamic.IfcElementQuantity q ON q.Element.Id = sp.ECInstanceId

• Target: spacesWithGrossArea / totalSpaces = 100%.

Diagnostic 2: Door Fire Rating & Clear Width Completeness

SELECT 
  COUNT(d.ECInstanceId) AS totalDoors,
  SUM(CASE WHEN p.FireRating IS NOT NULL AND p.FireRating <> '' THEN 1 ELSE 0 END) AS doorsWithFireRating,
  SUM(CASE WHEN p.FireRating LIKE '%20%45%60%' THEN 1 ELSE 0 END) AS ambiguousCatalogDoors,
  SUM(CASE WHEN p.ClearWidth IS NOT NULL OR d.BBoxHigh.x - d.BBoxLow.x > 0.5 THEN 1 ELSE 0 END) AS doorsWithValidWidth
FROM bis.GeometricElement3d d
LEFT JOIN IFCDynamic.ifcAspect_Pset_DoorCommon p ON p.Element.Id = d.ECInstanceId
WHERE (ec_className(d.ECClassId, 's.c') LIKE '%Door%' OR d.UserLabel LIKE '%Door%')

• Target: ambiguousCatalogDoors = 0, doorsWithValidWidth / totalDoors = 100%.

Diagnostic 3: Storey Containment Audit (Zero Floating Assets)

SELECT 
  ec_className(e.ECClassId, 's.c') AS elementType,
  COUNT(e.ECInstanceId) AS uncontainedCount
FROM bis.GeometricElement3d e
LEFT JOIN bis.ElementOwnsChildElements rel ON rel.TargetECInstanceId = e.ECInstanceId
WHERE rel.SourceECInstanceId IS NULL
GROUP BY ec_className(e.ECClassId, 's.c')

• Target: uncontainedCount = 0 for all physical classes.

Diagnostic 4: Multi-Discipline Partition Verification

SELECT 
  p.ECInstanceId AS partitionId,
  p.UserLabel AS partitionName,
  ec_className(p.ECClassId, 's.c') AS partitionType
FROM bis.InformationPartitionElement p
ORDER BY p.UserLabel ASC

• Target: Confirmation that Architectural, Structural, and Mechanical partitions are all present and populated.

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5. Summary: Scoring Your iModel's Completeness Index

$\text{Completeness Index } (I_{\text{comp}}) = 0.25 S_{\text{spatial}} + 0.25 S_{\text{geom}} + 0.30 S_{\text{pset}} + 0.20 S_{\text{federation}}$

When $I_{\text{comp}} \ge 0.95$, your facility iModel is fully verified and ready for official automated statutory certification and dynamic aspect publishing in BIM Checker.