What Is BIM and Why It Matters ?

The standard that defines BIM is being rewritten, and one of the things under revision is the word itself. Draft second editions of ISO 19650 parts 1 and 2 went out for public comment in March 2026, and they lean far harder on information management than on building information modelling. That drafting choice says more about what BIM really is than a decade of software demonstrations ever did.

A definition that survives contact with a contract

Ask ten people on a project what BIM is and roughly half will point at a model on a screen. The standard does not. ISO 19650-1:2018, subtitled Concepts and principles, frames the whole thing around information: what an organisation needs to know about its assets, who produces that knowledge, how it is checked, and how it is passed on when the scaffolding comes down.

The series splits the job across six parts, and knowing which part governs what saves a lot of circular argument in a design meeting:

• Part 1 (2018) sets the concepts, the vocabulary and the information delivery cycle.
• Part 2 (2018) covers the delivery phase, meaning design and construction.
• Part 3 (2020) covers the operational phase, once the building is in use.
• Part 5 (2020) covers security-minded information management, which matters far more than people expect on infrastructure and public buildings.
• Part 4 (2022) covers information exchange.
• Part 6 (2025) covers health and safety information, the most recent addition to the family.

Nothing in that list mentions a brand of software. That is not an accident.

The requirements chain nobody sees in a rendering

Under ISO 19650, information does not appear because a designer felt it would be useful. It is asked for, in writing, in a chain that runs downhill. An owner states what the organisation needs to run its estate, narrows that to what it needs from a specific asset, then narrows it again to what each appointed party must hand over and when. Those exchange requirements land in the appointment; the delivery team answers them with an execution plan describing how it intends to meet them.

Two model containers come out the other end. The project information model accumulates during design and construction. At handover, the parts the owner will actually use become the asset information model, which is the thing a facilities team lives with for the next thirty years. Most of the disappointment around BIM comes from projects that produced a beautiful first container and never defined the second.

The other half of the discipline is knowing when to stop. Level of information need is the formal way of saying that a door does not require a manufacturer’s screw specification at concept stage. It was standardised in Europe as EN 17412-1:2020 and has since moved to international status as ISO 7817-1:2024. Used properly it is a brake on modelling everything to the same obsessive depth, which is a real and expensive habit.

The common data environment does the unglamorous work

A common data environment is the single agreed place where project information is held, with a status attached to every container. That status is the whole point: work in progress means nobody else should build on it, shared means it can be used with judgement, published means it has been authorised. When people say a project is “doing BIM” but email drawings around as attachments, this is precisely what is missing.

What the 2026 revision changes

The most consequential change in the draft is structural: the wall between delivery and operation is coming down. Under the current arrangement, part 2 governs the project and part 3 takes over afterwards, which encouraged teams to treat handover as a finish line. In the draft second edition, part 2 covers both, and part 3 is being recast as implementation guidance supporting it.

The timetable, as tracked by the industry bodies feeding comments into the committee: parts 1 and 2 were open for public comment from March 2026 until 3 May, and part 3 until 6 July 2026. Publication is expected some way beyond that, and the drafts are still drafts, so nothing here should be written into a live appointment yet. It is worth watching rather than acting on.

Where the software actually fits

Software matters, but it is the layer that changes most often and locks you in hardest. Autodesk Revit, ArchiCAD and the Bentley Systems platforms all produce compliant deliverables in competent hands, and all three will happily produce an incoherent mess in the absence of stated requirements. The safeguard is the exchange format written into the contract: IFC 4.3 became ISO 16739-1:2024, which is what lets a model outlive the licence that made it.

Choosing between the platforms is a separate exercise with its own budget implications, and we have set out the feature and pricing comparison in our guide to BIM software features and pricing.

Does any of this pay off on a small project?

Yes, but only in proportion. A four-unit residential scheme does not need a forty-page execution plan; it needs someone to write down which drawings and data the client will receive at completion, in which format, and where they will live. That single page is ISO 19650 in miniature, and it is the part that prevents a client from discovering, three years later, that the as-built information exists only on a departed contractor’s laptop.

Is BIM the same thing as a 3D model?

No. A 3D model is geometry. BIM is the managed information about the asset, of which geometry is one part. A model with no data behind it, no status and no agreed recipient does not meet the definition in ISO 19650-1.

Who is responsible for information management on a project?

The standard assigns the function rather than the job title. The appointing party sets the requirements; a named information manager, who can sit on either side, runs the process. What matters is that the role is appointed explicitly, not assumed to be someone’s spare-time duty.

Does adopting BIM require replacing existing software?

Usually not at the start. The first move is to write the information requirements and set up a common data environment, both of which are process decisions. Tooling gaps become obvious once the requirements exist, and at that point they are informed purchases rather than hopeful ones.