LOIN — Level of Information Need (ISO 7817-1:2024)
TL;DR — read this first
LOIN is the international standard for specifying how much and what kind of information a deliverable must carry — separate from which standard governs the exchange (that is ISO 19650). The current, binding standard is ISO 7817-1:2024 (adopted in Europe as EN ISO 7817-1:2024), published 11 Aug 2024 and replacing EN 17412-1:2020. If a contract, software or article still cites "LOIN = EN 17412-1," they are citing the superseded edition.
Why LOD numbers broke
The "LOD 200 / 300 / 400 / 500" scheme came from AIA 202 (2013) and was popularised by the US industry and then borrowed into European BIM guidance. It measured model detail: what the model looks like at a given stage.
It failed for two reasons:
- It conflated "detail" with "content." A "LOD 300" model could be a pretty wall with no fire-rating metadata. LOD said nothing about what information must be attached to an element.
- It was tied to a project stage, not to a purpose. Two "LOD 300" models for the same stage could carry entirely different sets of usable data, because the model was driven by authoring effort, not by the downstream consumer’s need.
By 2018–2023, IFC 4-based openBIM tooling and procurement practice moved away from LOD numbers toward purpose-driven information specifications. The industry answer was LOIN: specify the information a consumer needs, at the moment they need it, at the level of definition they need.
What ISO 7817-1:2024 (LOIN) actually specifies
The scope of ISO 7817-1:2024 (per its abstract) is the concepts and principles for specifying the level and extent of information required to be exchanged and delivered across the built-asset life cycle — including strategic planning, initial design, engineering, construction, operation, maintenance, refurbishment and end-of-life.
Working terms:
- Level of Information Need (LOIN) — the defined detail and extent of information required for a specific purpose, at a specific point in the life cycle.
- Information deliverable — the concrete output that must satisfy a LOIN: a geometric model, a data set, a document, or a combination.
- Geometric information — level of detail, dimensionality, location, appearance, parametric behaviour.
- Alphanumeric information — identity, properties, relationships, metadata.
- Documentation — associated deliverables (schedules, specifications, validation evidence).
- Verification & validation — how a delivered information set is checked against the LOIN before it is accepted.
LOIN vs. LOD — what to put in a specification
| Question to answer | LOD answer | LOIN answer |
|---|---|---|
| What does the model contain? | "LOD 300" (vague) | Named objects with defined geometric + alphanumeric content |
| How detailed must the geometry be? | Implicit ("3D geometry with realistic details") | Explicit: dimensionality, level of detail, parametric behaviour |
| What metadata must travel with each element? | Not specified | Specified per object class (identity, properties, relationships) |
| How is the deliverable validated? | Not specified | Verification & validation principles |
| When is it delivered? | Project stage | Purpose-driven milestone |
Practical: how to write an EIR that uses LOIN
A working Exchange Information Requirements (per ISO 19650-2) with LOIN applied looks like:
- Purpose — why this information is needed (e.g., "for prefabrication cut lists").
- Timing — when it must be delivered (milestone, not a model stage).
- Objects — which object classes are in scope (door, window, MEP component, structural member).
- Geometric definition — required dimensionality, level of detail, parametric behaviour.
- Alphanumeric definition — identity, properties, relationships, metadata fields.
- Documentation — any associated deliverables (schedules, specifications).
- Format & exchange — file format (IFC, COBie, CSV), naming convention.
- Validation — how the deliverable will be verified against the LOIN before publication.
Where to read the current standard
- ISO 7817-1:2024 — Level of Information Need — Part 1: Concepts and principles (primary, international).
- EN ISO 7817-1:2024 — the European adoption; supersedes EN 17412-1:2020.
- CEN CEN/TC 334 — the TC that owns the LOIN series in Europe; watch for future parts (e.g., LOIN for specific asset types).
Related
- ISO 19650 — the standard that runs BIM information work — the companion standard for what information is needed and how it is exchanged
- BIM to FAB — from approved model to factory — where LOIN drives fabrication-ready detail
- BIM × AI — the operating system for AEC data — LOIN as the specification layer for AI-assisted model QA
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