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. BIM objects and detailed design An increase in the amount of detail extends to information about the specified products too. Rather than being copied and pasted from product literature or websites, data can be supplied directly by the manufacturer in the form of a digital ‘object’. BIM objects can be dragged and dropped from an object library directly into the design software, with the added benefit of knowing it is automatically the most up to date version. In the early stages of a project, generic BIM objects might be used – ‘placeholders’ that establish the principle of the design and how things will look, with a basic performance specification attached. As the detailed design is developed, generic objects are substituted for specific manufacturer BIM objects, developing the level of detail as the project grows. Manufacturer data isn’t limited to the size and shape of products, although this is obviously necessary for them to be accurately represented within the production information. The data also includes physical properties and performance characteristics that may have been tested (for example, thermal performance or fire rating). And it can store details of other technical information, like conformance with relevant standards and third-party certification. BIM and the future of construction Beyond the physical properties of the building and its components, BIM can include fourth, fifth and even sixth dimensions! These factor in time, costs and product lifecycling, giving a complete picture of the building over its lifespan and a more representative view for the end user than the basic up-front cost to build. The usefulness of BIM extends to the handover and occupation of the building. The owner or facilities manager can refer to the building model for the purposes of routine maintenance, unscheduled repairs, or any alterations or extensions to the building. It might help identify the position of a pipe or valve to make access quicker, easier and less disruptive. And because BIM objects include detailed information, if something needs replacing the model is able to give the exact product reference and contact details for the manufacturer. In other words, the model can exist, and be updated, from the conception of the project through to the decommission and demolition of the building. That has exciting implications for the future of the construction industry and the delivery of high quality, comfortable, sustainable buildings of all shapes, sizes and uses.

For more information on BIM: The information in the model talk to Glazing Vision Ltd