Who is responsible when AIA and BAP don't match?

The employer carries final responsibility for the AIA formulation, the supplier for translating it into a fitting BAP. When the AIA is unclear, the supplier can ask the employer — and should be contractually permitted to do so. This rights-and-duties chapter belongs explicitly in the contract.

Do I need an AIA even for a small project?

Yes, on every BIM project — even when the AIA is just 2 pages. The damage of a missing AIA shows only in the operations phase, when needed information is absent. A 2-page AIA always beats none.

Does LOIN replace the older LOD concept entirely?

Within EN ISO 19650 / DIN EN 17412: yes. LOD is no longer used in the standard. In US projects LOD remains common — an international owner should consider this in the AIA formulation, e.g. with a brief clarification of which definition applies.

[ Guides ]

AIA / BAP / LOIN explained

Anyone working with Building Information Modeling encounters three terms early: AIA, BAP, LOIN. They all come from the international BIM standard EN ISO 19650 (and its detail standard DIN EN 17412 for LOIN). They are not interchangeable, and they belong in a sequence: AIA defines what information the employer needs. BAP translates that into a plan for how the information is produced. LOIN specifies the depth at which the information must be delivered. This guide defines all three precisely, shows their relationship, and provides a concrete example from industrial plant engineering — how an owner formulates an AIA. Audience: owners, BIM managers, BIM coordinators on the owner side — even without BIM background.

Written by Ing. Andreas Huemer MSc, MBA — owner and managing director.

EN ISO 19650 — the standards frame

EN ISO 19650 governs information management across an asset's lifecycle. ISO 19650-1 covers concepts and principles, ISO 19650-2 the delivery phase. Before the standard, every project built bespoke BIM agreements — the standard provides a shared frame for information requirements, model exchange and accountability. National implementations: ÖNORM A 6241-2 in Austria, VDI 2552-series in Germany.

The three terms

AIA — Employer's Information Requirements — What the employer needs to know to operate the asset across its lifecycle. Content: structured list of information needs (geometric, alphanumeric, document-based) per asset, per phase, per use case. Author: the employer (often with owner-side PM support). Common error: writing AIA as 'all data' — overburdens suppliers and is not goal-directed.
BAP — BIM Execution Plan — The supplier's plan for fulfilling the AIA. Content: roles, software, model structure, model exchange cycles, QA processes. Author: supplier / general planner / project-side BIM manager. Common error: BAP decoupled from AIA — formally delivered but mismatched.
LOIN — Level of Information Need — Information delivery depth, separated into geometric, alphanumeric and document-based portions, per element and per phase. Governed by DIN EN 17412. LOIN replaces the older LOD concept (Level of Development) with an ISO-conformant, use-case-driven specification. Common error: writing LOIN as a global 'detail level' instead of use-case-specific.

Concrete example: industrial plant engineering site

An owner of a new industrial-plant-engineering site formulates the AIA with the use case 'maintenance planning in the operations phase'. For that, per machine, the owner needs: geometrically the 3D model with service spaces; alphanumerically manufacturer, type, maintenance interval; document-based the maintenance manual as an IFC attachment.

The general planner's BAP translates that into: model class map, software stack, exchange cycle with IFC version binding, QA process.

The LOIN regulates from which project phase what information density must be present — e.g. preliminary design without service spaces, execution phase with service spaces plus maintenance data.

Methodological foundation

The guide follows EN ISO 19650-1, EN ISO 19650-2, DIN EN 17412 and national implementations (ÖNORM A 6241-2 in Austria, VDI 2552-series in Germany). Methodological foundation for AIA drafting and BAP review: the PODBIM methodology. The owner is a Certified Digital BIM Practitioner EN ISO/IEC 17024.

Frequent questions

Who is responsible when AIA and BAP don't match? — The employer carries final responsibility for the AIA formulation, the supplier for translating it into a fitting BAP. When the AIA is unclear, the supplier can ask the employer — and should be contractually permitted to do so. This rights-and-duties chapter belongs explicitly in the contract.
Do I need an AIA even for a small project? — Yes, on every BIM project — even when the AIA is just 2 pages. The damage of a missing AIA shows only in the operations phase, when needed information is absent. A 2-page AIA always beats none.
Does LOIN replace the older LOD concept entirely? — Within EN ISO 19650 / DIN EN 17412: yes. LOD is no longer used in the standard. In US projects LOD remains common — an international owner should consider this in the AIA formulation, e.g. with a brief clarification of which definition applies.