BIM: The information in the model

Hearing the phrase ‘building information modelling’ conjures mental images of flashy 3D graphics, designed to show off the impressive architecture of some new multi-million pound landmark building.

That mental image is almost inevitable − after all, most of our built environment is judged on how it looks, fuelled by media reporting of ‘prizes’ like the Carbuncle Cup. But while rendered images and state-of-the-art visualisations have their place, they are not what building information modelling (BIM) is about exclusively.

BIM and shareable information

The ‘I’ in BIM is arguably the most important letter, because BIM is fundamentally about how information is shared rather than how it is presented. Although ‘modelling’ building information sounds advanced and suggests the need for complex software, even 2D CAD is classified as a form of BIM.

At that basic level, however, there are severe restrictions on how much information can be stored, presented and used by others. The ‘model’ comprises a set of drawings and a written specification, prepared by and under the control of the architect or design professional running the project.

Consultants such as structural engineers develop their own drawings, resulting in duplication of work − if the architectural drawings change, the amendments have to be made to the structural drawings too.

Varying BIM levels

As the ‘level’ of BIM rises, so the detail of the model and the quantity of information that can be held within it increases − including, if necessary, 3D images and visualisations of how the building will look. What the BIM level really defines is the extent of collaboration between parties, so the architect and consultants could all be working with a single shared model rather than separate ones.

Not only does that reduce duplication, it also identifies design issues much sooner thanks to ‘clash detection’. The software highlights potential conflicts between, say, structural elements and service runs, allowing them to be addressed earlier in the process. The knock-on benefit is to ensure that work on site progresses more smoothly, rather than on-site adjustments being made that risk compromising the building’s performance once occupied and in use.