I’ll keep the ‘definition’ part of this short. I like how thenbs.com describe it:

BIM is a process for creating and managing information on a construction project throughout its whole life cycle. As part of this process, a coordinated digital description of every aspect of the built asset is developed, using a set of appropriate technology. It is likely that this digital description includes a combination of information-rich 3D models and associated structured data such as product, execution and handover information.

NBS

The key here is: “a digital description of every aspect of the built asset“.

Simply put, BIM is about creating a digital version of a building. This is the first aspect of BIM: it is digital. We typically picture it as a 3D computer model but a BIM Model is essentially a database we look at with various different interfaces.

But crucially, most of the time it is a digital version of a building that does not exist yet.

Back at university, I once had a lecturer say to me “every building that is ever built is a prototype.” It is the first of its kind. Any other industry will build many prototypes before starting production. In building and construction, you just have the prototype. That’s it. You need to get it perfect in one go.

Construction is a process of risk-reduction. You start with high uncertainty and risk and this reduces as you build more and more of the project.

What this all means is that the BIM Model is subject to, and expected to undergo a lot of change over the course of its life. This is the second aspect of BIM: it is expected to change.

What about when construction is finished? Is the BIM Model done with? No, it can be used as a Digital Twin, to store real-time data on the buildings use and performance.

A building will live decades. We have buildings far older than software. Over the 50-year life of a building, how much will the BIM Model keep changing to still be useful for building management? This is the third aspect of BIM: there is no clearly defined end.

So a BIM Model is: a digital database, expected to change and can be constantly upgraded. The similarities to software are striking.

Agile is a project management method for software development that is designed to address things changing.

To read more, see my post on Agile.