BIM is a business process for generating, leveraging and managing building data to design, construct and operate the building during its lifecycle. It covers geometry, spatial relationships, light analysis, geographic information, quantities and properties of building components, project management, and post-construction facilities management.
BIM uses 3D, real-time, dynamic building modeling software to increase productivity in building design and construction.
The data can be used to illustrate the entire building lifecycle from cradle to cradle—from inception and design to demolition and materials reuse—including quantities and properties of materials (which can be easily extracted from the model) and the scope of works (including management of project targets and facilities management throughout the building’s life).
Furthermore, systems, components, assemblies and sequences can be shown in relative scale to each other and, in turn, relative to the entire project.
Managing a construction project and building lifecycle using BIM can result in substantial savings in both time and money—from design and construction through to ongoing maintenance.
The model saves time and waste on site, and renders extra coordination checks largely unnecessary; the information generated from the model leads to fewer errors on site caused by inaccurate and uncoordinated information.
When all members of the construction team work on the same model—from early design through to completion—introduced changes are automatically coordinated through BIM, across the whole project, and information generated is therefore of high quality.
BIM has already given the industry measurable positives:
According to the U.K. government, early BIM demonstration projects have already achieved savings of around 20 percent during the construction phase, with some on course to achieve 33 percent savings over the life of the building.
BIM is far more than 3D CAD modeling. It requires changes to the definition of traditional architectural phases, more data sharing than the construction industry is used to, and a willingness to embrace partnering in an approach that collects all project-related information digitally.
BIM is able to achieve this by modeling representations, specifications, and the critical paths of actual parts and components used in the construction process—representing a major shift from traditional computer-aided design.
There are four levels of BIM sophistication:
Level 0: This basic level involves separate sources of information in paper documents.
Level 1: This level involves separate sources of information in semi-structured electronic documents, often involving 2D/3D CAD.
Level 2: This level involves file-based electronic information with some automated connectivity. It will include post-construction information such as operation and maintenance of assets and the management activity for the life of the asset.
Level 3: This level involves integrated electronic information with full automated connectivity. Level 3 BIM is a fully integrated and collaborative process that includes project lifecycle and facility management information enabled by Web services.
Another terminology commonly used is “BIM dimensions.” Currently, these are defined as follows:
3D BIM: This provides a visualization tool enabling designers and contractors to work together to identify and resolve problems with the help of the model.
4D BIM: This is 3D BIM plus the construction workflow planning, scheduling, and management. As the design is changed, advanced BIM models will be able to automatically identify those changes that will affect the critical path and indicate what the corresponding impact will be on the overall delivery of the project.
5D BIM: This is 4D BIM plus the project’s construction cost and requirements. With BIM, the model includes information that allows a contractor to accurately and rapidly generate an array of essential estimating information, such as materials quantities and costs, size and area estimates, and productivity projections. As changes are made, estimating information automatically adjusts, allowing greater contractor productivity.
The industry is already discussing 6D BIM, which is 5D BIM plus facility management. Extending this further, 7D BIM could be 6D BIM plus building analytics.