Walkthrough: Configuring & Validating a Hospital iModel

Overview & Scenario

Healthcare facilities represent one of the most demanding challenges in digital engineering. They require rigorous compliance with statutory NHS standards—including Health Building Notes (HBN), Health Technical Memoranda (HTM), and British accessibility codes (BS 8300-2). Traditional manual coordination often overlooks critical issues:

• "The 900mm Illusion": Doors specified as nominal $915\text{mm}$ fail clinical bed transfer and wheelchair clearances once frame stops and open door leaves are deducted.
• Floor-to-Soffit Clearances: Overhead MEP ductwork and structural downstand beams clashing with minimum $2.40\text{m}$ ceiling heights.
• Corridor Bottlenecks: Architectural structural columns narrowing bed circulation routes below $2.00\text{m}$.
• Fire Compartment Mismatches: Unrated doors installed in $60\text{-minute}$ fire-rated walls.

In this walkthrough, we configure and validate a federated healthcare digital twin using the NHS Darlington Memorial Hospital (IFC_Hospital) as our real-world exemplar.

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Preconditions

Before beginning this walkthrough, ensure:

1. You are signed into BIM Checker with your organizational credentials.
2. You hold an Author or Publish license entitlement.
3. Your Bentley iTwin container has the IFC_Hospital iModel synchronized to its latest changeset.
4. The federated model includes the 7 core discipline partitions:
   • WRSH_Architectural.ifc (Rooms, walls, doors, stairs)
   • WRSH_Structural.ifc (Columns, framing beams, floor slabs)
   • WRSH_Mechanical.ifc (HVAC duct runs, air handling units)
   • WRSH_Plumbing.ifc (Domestic water, foul drainage)
   • WRSH_Electrical.ifc (Cable containment, panels)
   • WRSH_Sprinkler.ifc (Fire protection lines)
   • WRSH_MedicalGas.ifc (Medical gas distribution)

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Step 1: Connect the Federated Hospital iModel

1. Open BIM Checker in your web browser.
2. In the top project context bar, select your iTwin (e.g., Healthcare Estate Development).
3. In the iModel dropdown, select IFC_Hospital.
4. Confirm that the Changeset Navigator displays the latest synchronized changeset hash (e.g., cs-1e28f7a7...).
5. Navigate to iModel Browser to verify that all 7 discipline models are loaded and active.

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Step 2: Select and Activate the Healthcare Validation Profile

BIM Checker operates on a Single Active Configuration Paradigm to guarantee consistent compliance scoring across all project stakeholders.

1. Navigate to BIM Requirements from the main navigation sidebar.
2. Click the Validation Config Selector dropdown in the workbench header.
3. Select the Hospital (UK NHS Healthcare Standards) configuration.
4. The system loads the 10 statutory healthcare rules:
   • HOSP-PLN-001: Relational Gross Floor Area (GFA) Reconciliation
   • HOSP-PLN-002: HBN 00-01 Clinical Space Area Compliance
   • HOSP-PLN-003: Healthcare Functional Zoning & Proximity
   • HOSP-EVAC-001: Door Clear Width & Bed Access ("The 900mm Illusion")
   • HOSP-EVAC-002: Corridor Bed Transport & Circulation Width
   • HOSP-EVAC-003: Progressive Horizontal Evacuation Travel Distance
   • HOSP-EVAC-004: Healthcare Evacuation Stair Clear Width & Pitch
   • HOSP-CLR-001: Floor-to-Soffit Minimum Headroom under MEP Drops
   • HOSP-FIRE-001: HTM 05-02 Firecode Wall & Door Fire Resistance
   • HOSP-ACC-001: Accessible Sanitary Facility Turning Circles

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Step 3: Bind the Asset Register & Contractual Targets

Statutory planning compliance requires comparing live model geometry against contractual architectural briefs.

1. In the BimRequirements Header, open the Asset Preset Selector.
2. Select preset-nhs-darlington-hospital.
3. Confirm the contractual design targets are populated:
   • Facility Name: Darlington Memorial Hospital - New Acute Wing
   • Contractual Planned GFA: $25,000\text{ m}^2$ multi-storey gross / $10,500\text{ m}^2$ net enclosed clinical brief.
   • Storeys: 8 storeys (Levels 1 through 7 + intermediate Level 7A; total height $34.0\text{m}$).
   • Jurisdiction: UK_NHS (NHS England Health Building Notes).

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Step 4: Configure Rules & Geometric Tolerances

Expand each rule accordion in the BIM Requirements Workbench to inspect or tune parameters:

1. Clinical Space Sizing (HOSP-PLN-002)

• Standard: NHS HBN 00-01 (Clinical Space Briefs).
• Rule Configuration:
  • ICU Room: Minimum area $\ge 26.0\text{ m}^2$
  • Operating Theatre (OR): Minimum area $\ge 40.0\text{ m}^2$
  • Consultation / Exam: Minimum area $\ge 12.0\text{ m}^2$
  • Inpatient Single En-Suite Bedroom: Minimum area $\ge 16.0\text{ m}^2$
• Detection: Flags uncomputed spaces and spaces where modeled square meterage fails clinical guidelines.

2. Door Clear Width & "The 900mm Illusion" (HOSP-EVAC-001)

• Standard: NHS HBN 00-04 Section 4.2.1, BS 8300-2.
• The Challenge: Standard $915\text{mm}$ doors are often assumed to be $900\text{mm}$ clear openings. In reality: $W_{\text{effective}} = W_{\text{nominal}} - 2 \cdot t_{\text{frame}} - t_{\text{leaf}} = 915\text{mm} - 30\text{mm} - 44\text{mm} = 841\text{mm}$ This provides only $841\text{mm}$ clear opening—violating the $900\text{mm}$ wheelchair requirement and failing the $1,200\text{mm}$ acute bed transfer limit.
• Rule Configuration:
  • Bed Transfer Doors: Threshold $\ge 1.20\text{m}$
  • General Accessible Doors: Threshold $\ge 0.90\text{m}$
  • Frame Stop Deduction: $2 \times 15\text{mm} = 30\text{mm}$
  • Leaf Thickness Deduction: $44\text{mm}$
  • 3D Swing Envelope: Enabled ($90^\circ$ sweep)

3. Corridor Bed Transport Bottlenecks (HOSP-EVAC-002)

• Standard: NHS HBN 00-04.
• Rule Configuration:
  • Corridor Clear Width: Threshold $\ge 2.00\text{m}$
  • Warning Buffer: $0.10\text{m}$ (alerts at $2.00\text{m} - 2.10\text{m}$)
• Detection: Sweeps the medial axis of circulation spaces, detecting structural columns or protruding utility panels that pinch the corridor down to $1.4\text{m}$.

4. Floor-to-Soffit Minimum Headroom under MEP Drops (HOSP-CLR-001)

• Standard: NHS HBN 00-04, HTM 03-01.
• Rule Configuration:
  • Minimum Clear Height: $\ge 2.40\text{m}$
  • Measurement Method: $\text{BBoxLow.z} - \text{StoreyFFL.z}$
• Cross-Discipline Target: Evaluates structural downstand beams in WRSH_Structural and HVAC supply ducts in WRSH_Mechanical.
• Level 7A Critical Focus: On Level 7A ($31.0\text{m}$) where slab-to-slab height is restricted to $3.0\text{m}$, deep beams and supply ducts create critical head-height violations.

5. Firecode Wall & Door Resistance Matching (HOSP-FIRE-001)

• Standard: NHS HTM 05-02 Firecode, BS 9999.
• Rule Configuration:
  • Wall Integrity Target: $60\text{ minutes}$ (EI 60)
  • Door Matching Requirement: FD60S
• Detection: Identifies doors with missing fire rating attributes installed in fire-rated partition walls, and flags ambiguous annotations (e.g. '20 minute, 45 minute, 60 minute').

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Step 5: Execute the Audit & Inspect 3D Telemetry

1. In the BimRequirements Workbench header, click Run All Requirements.
2. BIM Checker queries live ECSQL geometry, executes the analytical handlers, and returns results in seconds.
3. Review the executive summary cards:
   • Total elements evaluated: $\approx 1,280$ components across architectural and MEP disciplines.
   • Pass rate: $\approx 84.6%$.
4. In the rules list, expand HOSP-EVAC-001 (Door Clear Width):
   • Notice that 310 doors are flagged with effective widths of $841\text{mm}$ (
     lt; 1,200\text{mm}$).
5. Click on defect Door 0x200000010f2:
   • The 3D viewport automatically animates, centering the camera on the door.
   • Surrounding elements fade to context, and the door is highlighted in red.
6. Open the Levels & Models Panel on the left:
   • Check WRSH_Mechanical.ifc and isolate Level 7A.
   • Expand rule HOSP-CLR-001 and click a soffit defect to inspect the HVAC duct clash where clear headroom drops to $2.15\text{m}$ (
     lt; 2.40\text{m}$).

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Step 6: Publish Dynamic Aspects to the Live iModel

Once the audit is reviewed and verified:

1. Click Publish to iModel in the workbench header.
2. In the confirmation dialog, review the publishing payload:
   • Target Changeset: cs-1e28f7a7...
   • Target Aspect: IFCDynamic.Pset_BIMChecker_ExecutionAudit
   • Non-compliant elements receiving IFCDynamic.Pset_BIMChecker_Fail: 342 assets.
3. Click Confirm & Publish:
   • BIM Checker writes the dynamic aspects directly to the live iModel repository.
   • Historical audit records are written to the database.
4. The Verified Audit Provenance Banner activates:

   Verified Statutory Audit: 84.6% Compliance | NHS Health Building Notes | Audited on Changeset cs-1e28f7a7

5. Click Download Audit Report (PDF) to export a formal, print-ready statutory compliance report.

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Verification & Rollback

• Verification: In Property Analysis, run:

  SELECT ECInstanceId, AuditStatus, RuleId, DefectReason 
  FROM IFCDynamic.Pset_BIMChecker_ExecutionAudit
  

  The query should return the latest audit run with timestamps matching your session.
• Rollback: To discard local parameter overrides, open Settings, select the Hospital configuration, and click Reset to Statutory Defaults.