Building Information Modelling/Modeling - BIM

In its purest form, BIM provides a single source of information from all project members. The current practice is for each discipline to hold their own model (see Building Information Model) within their domain, and regularly issue the model (or information from it) to a central location where all the information is collated. This is the basis of “Level 2 BIM”, as required by the UK Government Construction Strategy on UK government projects (since April 2016).

Information is typically hosted (or visualised) within a 3D representation of the building. This provides an easy-to-understand interface for the team, the client, end users, etc. Modelling in 3D also helps with coordination and can feed into fabrication tools. By hosting the data within this environment, anyone can select an item in the model and immediately view its properties.

The information provided in a model does not have to be any different to the information provided in schedules or specifications. BIM does not change what information is provided, it is just a different way of presenting that information.

Another area of focus for BIM is re-using the model and its data. Rather than each consultant or specialist having to manually re-enter areas, equipment loads, circuit references, etc. on each drawing, model, schedule and calculation, it can all be taken from and added to the same database. This is an area that can save much time in the current design and construction process.

So BIM does not radically change the way we design buildings, but it is a process that should improve the quality and consistency of the information shared amongst project teams, and also offer real opportunities for increased efficiency throughout the industry.

The UK BIM Task Group confirms that there are many definitions of what BIM is and in many ways it depends on your point of view or what you seek to gain from the approach.

Sometimes it’s easier to say what BIM isn’t!
- It’s not just 3D CAD
- It’s not just a new technology application
- It’s not next generation, it here and now!
BIM is essentially value creating collaboration through the entire life-cycle of an asset, underpinned by the creation, collation and exchange of shared 3D models and intelligent, structured data attached to them.

We have been explicit in asking for Level 2 BIM in the maturity ramp (as illustrated); this is defined as “file based collaboration and library management.”
Level 2 BIM maturity can be achieved through a series of different process and tools. Crudely defined, Level 2 BIM is a series of domain specific models (e.g. architectural, structural, services etc) with the provision of a single environment to store shared data and information (in our case COBie UK 2012).

The US National Building Information Model Standard Project Committee defines BIM concisely as….

Building Information Modeling (BIM) is a digital representation of physical and functional characteristics of a facility. A BIM is a shared knowledge resource for information about a facility forming a reliable basis for decisions during its life-cycle; defined as existing from earliest conception to demolition.

One of the early governmental adopters was the US General Services Administration who quickly saw the potential benefit of BIM (as included in their comprehensive 2007 BIM Guide)

The purpose of BIM is to make the design information explicit, so that the design intent and program can be immediately understood and evaluated. A BIM-based approach supports ‘on demand’ generation of documents (e.g., drawings, lists, tables, and 3D renderings) from a consistent BIM. In a sense, these documents present views of the current BIM. A BIM model, therefore, can live longer, contribute more to process efficiency, and provide superior accuracy than traditional 2D CAD drawings.
As a shared knowledge resource, BIM can reduce the need for re-gathering or re-formatting information. This can result in an increase in the speed and accuracy of transmitted information, reduction of costs associated with a lack of interoperability, automation of checking and analysis, and unprecedented support of operation and maintenance activities.

Chuck Eastman (seen as one of the 'fathers of BIM') provides the following on the (now moribund) Georgia Tech BIM site that provides the base point for the future exploitation of BIM…

BIM involves representing a design as objects – vague and undefined, generic or product-specific, solid shapes or void-space oriented (like the shape of a room), that carry their geometry, relations and attributes. The geometry may be 2D or 3D. The objects may be abstract and conceptual or construction detailed. Composed together these objects define a building model (not a BIM, in Chuck Eastman's view). If an object is changed or moved, it need only be acted on once. BIM design tools then allow for extracting different views from a building model for drawing production and other uses. These different views are automatically consistent - in the sense that the objects are all of a consistent size, location, specification - since each object instance is defined only once, just as in reality. Drawing consistency eliminates many errors.

Modern BIM design tools go further. They define objects parametrically. That is, the objects are defined as parameters and relations to other objects, so that if a related object changes, this one will also. Parametric objects automatically re-build themselves according to the rules embedded in them. The rules may be simple, requiring a window to be wholly within a wall, and moving the window with the wall, or complex defining size ranges, and detailing, such as the physical connection between a steel beam and column.

Mott MacDonald (a management, engineering and development consultancy) concisely define BIM as …

A coordinated set of processes, supported by technology, that adds value through creating, managing and sharing the properties of an asset throughout its lifecycle