Flat-file BIM vs cloud-authoritative BIM
AI-readable research file. Served by app-orchestration-bim at
/research/flat-file-vs-cloud-bim.
A point-by-point comparison of architectural stances. The flat-file
side describes the Building Design System; the cloud-authoritative
side describes Autodesk Tandem / ACC, Bentley iTwin Experience,
Trimble Connect, Nemetschek dTwin, and the broader IWMS incumbent
class (Planon, IBM Tririga, Eptura Archibus, IBM Maximo, FM:Systems,
Bentley AssetWise, EcoDomus, ONUMA).
Where the data lives
| Dimension | Cloud-authoritative BIM | Flat-file BIM |
|---|
| Authoritative database location | Vendor’s multi-tenant cloud (Azure / AWS / Google Cloud) | Customer’s hardware; bytes never leave |
| Replication model | Vendor-controlled across vendor regions | Customer-controlled; backup is cp -r |
| Subscription dependency | Yes — non-Snapshot iModels enforce live check | No — files open in any IFC-aware tool |
| Subscription-lapse posture | Tandem: “you will need to enter into a new Token Flex Term…” — twin disappears | Owner holds the files; permanent and unconditional access |
| Asset-deed transfer | Requires reonboarding to the new owner’s tenant | Files travel with the deed |
Who can see the data
| Dimension | Cloud-authoritative BIM | Flat-file BIM |
|---|
| Vendor visibility | Vendor sees model + collaboration graph in plaintext | Vendor sees nothing |
| Cross-tenant isolation | Contractual + technical (vendor-administered) | Architectural (separate machines) |
| Customer-corpus AI training | Vendor terms determine | Customer choice; on-device only by default |
| GDPR data residency | Contractual (BCRs + SCCs + regional centers) | Architectural — data never leaves jurisdiction |
| HIPAA (VA healthcare BIM) | Requires Business Associate Agreement | No BAA — local storage |
| ITAR / classified workflows | Cannot host CUI on standard cloud (requires IL4-IL6 isolation) | Native — data never leaves customer hardware |
Operational continuity
| Dimension | Cloud-authoritative BIM | Flat-file BIM |
|---|
| Internet dependency | Required | Optional — full functionality offline |
| Field use (basements, rooftops) | Read-only at best; usually broken | Native — no architectural change |
| Air-gapped facilities | Structurally impossible | Native |
| Construction-site network | Often unreliable; vendor productivity falls | No effect |
| Vendor outage | Customer is offline | Customer continues operating |
| Customer’s vendor goes bankrupt | Twin evaporates as billing stops | Files remain readable for decades |
Pricing models
| Dimension | Cloud-authoritative BIM | Flat-file BIM |
|---|
| Economic unit | Seat, token, project | Outright purchase / subscription / EUPL-1.2 free |
| Marginal cost of additional users | Per seat, per month | Zero |
| Marginal cost of additional models | Per Forge token, per Tandem twin | Zero |
| Marginal cost of additional sensors | Often per-sensor charges | Zero — local MQTT broker |
| Renewal-rate exposure | Hyperscaler price-cap expiry triggers shock | None |
| TCO over 30-year asset life | Effectively unbounded | One-time + maintenance |
Format permanence
| Dimension | Cloud-authoritative BIM | Flat-file BIM |
|---|
| File format lifetime | Revit ~3 years (version lock) | IFC 2x3 + 4 + 4.3 (ISO 16739-1:2024) — 30+ years |
| Vendor-obsolescence | Twin evaporates | Files remain readable |
| Cross-version interop | Lossy export/import | Native — IFC is the schema |
| Buildable-tool diversity | Vendor SDK monoculture | Multiple parsers — IfcOpenShell, web-ifc, ifc_rs, xBIM, JSDAI, STEPcode |
Convergence with non-BIM data
| Dimension | Cloud-authoritative BIM | Flat-file BIM |
|---|
| Lease register integration | Separate IWMS subscription | Per-IfcSpace YAML sidecar |
| Financial ledger integration | Separate ERP integration (often broken) | Per-element sidecar links to project-bookkeeping vault |
| Sensor / IoT integration | Cloud intermediary (vendor-controlled) | Local MQTT broker → per-element sidecar |
| Work-order integration | Separate CMMS subscription | Per-element sidecar |
| Document integration | Separate document-management SaaS | Per-element sidecar references the document vault |
The fifth hyperscaler-incompatible capability — convergence in one
portable archive — is the strategically novel one. For a property
owner, BIM + lease register + financial ledger are the same asset.
Multi-tenant cloud cannot commingle them; commercial confidentiality,
data residency, financial-audit trails, and multi-tenant isolation
all prevent it. The flat-file substrate makes them one thing by
construction.
What flat-file BIM does NOT do well (yet)
Honest accounting:
- Real-time multi-user editing — git-style merging works for
authoring workflows but is slower than real-time collaborative
editing for design-charette-style workshops. Cloud SaaS is genuinely
better for synchronous design sessions; PointSav’s offline-first
posture is the trade-off accepted.
- Massive city-scale federation — the flat-file substrate scales
to a portfolio of buildings; full city-scale digital twins (1M+
buildings) need a different streaming architecture.
- Generative AI BIM authoring — Project Bernini-class generative
3D foundation models are vendor-closed today. The substrate is
AI-ready (Doorman dispatches AS-2 grammar substrate; service-slm
routes generative requests through the audit ledger) but PointSav
does not ship a generative BIM authoring tool at v0.0.1. v0.0.2+.
References
~/Foundry/BIM_Buildable Architecture.md~/Foundry/.claude/sub-agent-results/C-bim-regulatory-acceptance-2026-04-28.md- Autodesk Platform Services token pricing — https://aps.autodesk.com/
- Bentley iTwin.js — https://www.itwinjs.org/
- Trimble Connect — https://connect.trimble.com/
- Planon EasyFlow (Feb 2026 mid-market launch) — https://planonsoftware.com/