This is a delivery-method resource, not project-specific design. Electrical protection, cable sizing, cooling capacity, fire strategy and structural loads require the appointed designers and the applicable codes. Technical review of this cluster by a named senior BIM/MEP lead is pending; do not treat it as sealed guidance.
BIM specifications often include a single LOD number — LOD 300, LOD 350, LOD 400 — as if this communicates what information the model should contain. It does not. LOD originated as shorthand for level of development or level of detail, typically tied to design stages. Without context, a LOD number tells the modeller how much geometry to draw but not what data to include, for what use, or at what exchange. ISO 19650 addresses this with level of information need — a purpose-driven approach.
The LOD problem
Level of development tables exist — the US-based BIMForum publishes a widely referenced specification. But LOD numbers were designed for a different context: US design-bid-build projects with specific liability handoffs between stages. Applied to a dense MEP data-center project with multiple prefabrication packages, integrated vendor models, and handover-data requirements, a single LOD number creates ambiguity.
- Does LOD 350 mean all elements? Or only specified systems?
- Does it include non-geometric data — asset tags, maintenance schedules, commissioning data?
- Who defines what 350 means for a data-hall CRAH unit — BIMForum, the project BEP, or the vendor?
- Is the same LOD required for coordination, fabrication and handover — three different uses?
ISO 19650 language: level of information need
ISO 19650-1 introduces level of information need as the framework for specifying information requirements. The concept separates geometry from data and ties both to purpose. UK BIM Framework Guidance Part 1 explains the approach: define what information is needed for a specific use, at a specific exchange, rather than applying a blanket LOD across the project.
The older terms — LOD (level of development/detail) and LOI (level of information) — remain in common use. Many practitioners use LOD for geometry and LOI for data. ISO 19650 does not prohibit these terms but encourages thinking in terms of purpose-driven requirements rather than numerical labels.
Components of level of information need
When specifying level of information need, consider four dimensions:
Level of information need dimensions
| Dimension | Question | Example |
|---|---|---|
| Geometry detail | What level of geometric representation is required? | Schematic placeholder vs accurate envelope vs fabrication-ready geometry. |
| Data attributes | What non-geometric information is required? | Asset tag, manufacturer, model, maintenance interval, warranty expiry. |
| Purpose | Why is this information needed? | Spatial coordination, clash detection, fabrication, FM handover. |
| Exchange | When is this information needed? | Concept design, detailed design, construction, practical completion. |
This structure allows different requirements for different elements, different stages and different uses. A CRAH unit may need accurate footprint and connection points for coordination but detailed internals only if the manufacturer provides them and the FM system will consume them.
Data-center examples
How level of information need applies to typical data-center elements:
LOIN examples for DC elements
| Element | Purpose | Geometry need | Data need |
|---|---|---|---|
| Busway run | Coordination | Accurate routing, tap-off locations, bend radii | System tag, load capacity, future extension reserve |
| Busway run | Fabrication | Connection interfaces, support positions | Part numbers, manufacturing codes |
| CRAH unit | Coordination | Footprint, coil-pull envelope, connection stubs | Airflow direction, cooling capacity |
| CRAH unit | FM handover | As-installed position | Asset ID, manufacturer, model, warranty, maintenance schedule |
| Cable tray | Coordination | Routing, segment lengths, junctions | Fill ratio assumption, fire rating |
| Switchgear | Coordination | Envelope including rack-out clearance | Fault rating, circuit designations |
These are examples, not prescriptions. The project EIR should define what information is needed, and the BEP should confirm how it will be produced.
Migrating from LOD to LOIN
If your project already uses LOD, you do not need to discard it. Treat LOD as a shorthand for geometry detail and supplement it with data requirements and purpose statements. Over time, shift toward purpose-driven specifications.
- Keep existing LOD language if it is embedded in contracts — do not break working agreements.
- Add data requirements explicitly: asset tag, parameters for FM, commissioning fields.
- State the purpose: this information is needed for coordination / fabrication / handover.
- In new projects, specify level of information need from the start rather than retrofitting LOD.
FAQ
- Is LOD obsolete?
- Not obsolete, but insufficient. LOD remains a useful shorthand for geometry detail stages. ISO 19650 language adds purpose and data requirements. Many projects use both: LOD for geometry, plus explicit data specification.
- Where do I document level of information need?
- In the exchange information requirements (EIR) — what the appointing party needs — and confirmed in the BEP — how the appointed party will deliver it. Some projects use a separate LOIN schedule or model element matrix.
- Does every element need a LOIN specification?
- Not necessarily. Group similar elements and specify by category. Define exceptions where specific elements need higher or lower detail. The goal is clarity, not bureaucracy.
Sources
- 1. ISO, ISO 19650-1:2018 — Organization and digitization of information about buildings and civil engineering works, including building information modelling (BIM) — Part 1: Concepts and principles (2018). https://www.iso.org/standard/68078.html. Accessed 2026-09-03.
- 2. ISO, ISO 19650-2:2018 — Information management using building information modelling — Part 2: Delivery phase of the assets (2018). https://www.iso.org/standard/68080.html. Accessed 2026-09-03.
- 3. UK BIM Framework, Information management according to BS EN ISO 19650 — Guidance Part 1: Concepts (2nd edition) (2019). https://ukbimframework.org/wp-content/uploads/2019/10/Information-Management-according-to-BS-EN-ISO-19650_-Guidance-Part-1_Concepts_2ndEdition.pdf. Accessed 2026-09-03.
- 4. BSI, ISO 19650 — Building Information Modelling (BIM) (2026). https://www.bsigroup.com/en-GB/products-and-services/standards/iso-19650-building-information-modelling-bim/. Accessed 2026-09-03.