20 Relationship to existing work§
20.1 Position§
BUS-1 sits above the semantic modeling standards. It does not replace them, compete with them, or profile them. It specifies what an owner must be handed and what a receiving system must be able to reconstruct, which is a question none of them asks.
Formal mappings are deliberately not part of v0.2. Publishing a mapping to a specification that is itself unpublished or pre-release would bind this standard to another body’s schedule, and 7.7 preserves external classifications losslessly without one.
20.2 The semantic modeling standards§
| Standard | Status, July 2026 | Relationship |
|---|---|---|
| ASHRAE SPC 223P | Project committee, unpublished. Second advisory public review closed August 2025. Models type, topology, composition, telemetry linkage, characteristics, in RDF. | Complementary. No intent, knowledge, geometry, graphics, alarms, events, or exchange package. Its classes are a natural classification value. |
| Brick Schema | v1.4.4 stable, v1.5.0-rc1 pre-release. Brick Consortium, not a standards development organization. | Complementary. Equipment and point taxonomy, carried in classifications. |
| Project Haystack | Version 4.0.0 is the current published defs release. Haystack 5 with Xeto announced 2025, unreleased. | Complementary. Tag vocabulary in classifications. Five serializations, two explicitly lossy, and no package concept. |
| RealEstateCore | v4.0.0, distributed inside Brick releases. Harmonized, not merged. | Complementary. Spatial and real-estate concepts, plus the only native geometry among these. |
| ISO 16739-1:2024 (IFC) | Second edition, March 2024, schema IFC 4.3.2.0. | Adjacent. Design and handover with 3D geometry BUS-1 does not carry. No telemetry, no point addressing; ControlElementId was removed in IFC4. |
| ANSI/ASHRAE 135-2024 (BACnet) | Protocol Revision 31. Addendum 135-2012ba added a Tags property in 2016. | Below. Its tag mechanism defines a container and no vocabulary, and it has no bulk export or configuration portability. |
| ANSI/ASHRAE 231-2026 (CDL) | Published February 2026. | Adjacent. Design-time control description. Referenced by bus:Sequence, not extracted. |
20.3 The portability gap§
No standard, in any body, requires a building technology vendor to hand over a reconstitutable package of a building’s operational system, and none defines what such a package would contain.
| Component of an exit package | Can be serialized by | Compelled by |
|---|---|---|
| Point and asset model | Brick, Haystack, 223P | nothing |
| Historical time series | nothing, as a package | EU Data Act, partially, for device-generated data |
| Graphics with bindings | nothing — clause 13 of this document | nothing |
| Control logic | ASHRAE 231, at design time | nothing |
| Schedules, alarm configuration, analytics rules | nothing | nothing |
| Integration and driver configuration | nothing | nothing |
ASHRAE Guideline 13, the natural home for such a requirement, covers architecture, input and output structure, communication, configuration, testing, and documentation, and contains no section on owner data rights or vendor exit. Software escrow has no ISO, ANSI, or BSI standard and appears rarely in building automation contracting. Independent data layer architectures are widely discussed and have no specification, governance body, or exit mechanism.
20.4 Portable presentation: the evidence and the precedents§
Point semantics are standardized, geometry is standardized, transport is standardized. The symbol on a page bound to a live point is standardized nowhere, and every effort in this field has explicitly placed it out of scope.
Three pieces of evidence establish that the rebuild cost is structural rather than incidental. Schneider published TGML as a format specification in 2010 and its own knowledge base states that artwork travels but "all of the binding and linking information would be lost," because bindings live in the database. Johnson Controls’ own N1-to-Metasys conversion utility drops color-change, animation, and sizing dynamics and requires manual rebinding. And QA Graphics, the dominant third-party graphics house, organizes its service line by platform with no conversion service between them — its business model is the missing format.
Two precedents outside buildings show the problem is tractable, and clause 13 is measured against them:
- IEC 61970-453 — the CIM Diagram Layout Profile exchanges diagram geometry in which each diagram object links to the underlying modeled power-system object. Real bindings, machine-readable, in production. It does not exchange symbol libraries or styling, and carries static layout rather than rendering rules — which is precisely the division clause 13 adopts.
- IEC 61804-3 (EDDL) — a standardized, vendor-portable description language including menus, graphical representations, and a graphing system bound to device parameters. The one place a standards body shipped portable graphics with data bindings. Its scope is device faceplates, not plant graphics.