Building Information Modelling (BIM) uses software to create a three dimensional model of a building that allows any changes that are made to be shown in a way that would be seen in the real building. BIM does this by creating the virtual equivalents of the actual building parts used to construct a building. This enables all aspects of the design and build process to be worked on collaboratively by the stakeholder, contractors and engineers involved in the project.
BIM systems can be used in different ways. Some companies will use BIM as advanced Computer Aided Design (CAD) whilst others as a series of models for separate elements of a project. For those comfortable with the technology, a single integrated model is the goal. Building information model users often achieve cost savings but also benefit from integrated, construction sequencing and facilities management capabilities.
Where CAD depicts construction elements with lines that define a structure’s geometry, BIM creates each element of the structure as an “intelligent” object containing a broad array of information (parametric data) in addition to its physical dimensions. Each element in the BIM model “understands” how it relates to other objects to the design in general.
Within BIM walls are objects, which can be joined, shortened and repositioned and which “know” that they have certain properties and characteristics. A wall for example in the BIM the model “understands” that it is positioned from foundation to level 1. If either of those parameters changes, the height of the wall will automatically adjust to match. Similarly windows and stairs “understand” their relationship to the walls in which they are located and behave accordingly.
Contractors can use a BIM model to “rehearse” construction, coordinate drawings and prepare shop and fabrication drawings.
Designers can use BIM to explore alternative concepts, conduct value engineering and optimise their designs.
Owners can use BIM to optimise building maintenance, renovations and energy efficiency, as well as to monitor life cycle costs.
Building Information Model enables collaboration among designers, owners and contractors in ways the construction industry has never known before.
There are two kinds of BIM software: Authoring Software and Coordination Software. Authoring software is used to design the main aspects of the project. However different contractors and engineers involved in the project will often be using specialised software for their particular discipline and this information needs to be built into the BIM project via coordinating software. It as anticipated that as the technology matures single software packages will be used that contain both elements.
Common authoring software platforms include: Autodesk’s Revit and Naviswork’s Applications.
From 2016 the Government are insisting that building information modelling are used by all participants in a construction project. Both the professional and construction teams will need to have invested in compatible technology and staff training so all the design information, costing and programming information and other material can be centrally managed in a single BIM model.
BIM is being used at the moment at a number of different levels of sophistication:
Level 0 – Unmanaged CAD in 2D with paper or electronic paper data exchange.
Level 1 – Managed CAD in 2D or 3D format with a collaborative tool providing a common data environment with standardised approach to data structure and format. Commercial data will managed by standalone finance and cost management packages with no integration.
Level 2 – A managed 3D environment held in separate discipline BIM tools with data attached. Commercial data will be managed by enterprise resource planning software and integrated by proprietary interfaces or bespoke middleware. This level of BIM may utilise 4D construction sequencing and/or 5D cost information. The Governments BIM strategy Paper calls for the industry to achieve level 2 BIM by 2016.
Level 3 – A fully integrated and collaborative process enabled by “web services” and compliant with emerging Industry Foundation Class (IFC) standards. This level of BIM will utilise 4D construction sequencing, 5D cost information and 6D project lifecycle management information.