Building information modelling BIM
See also our Step-by-step guide to using BIM on projects supported by more than 100 linked articles.
Building Information Modelling (BIM) is a very broad term that describes the process of creating and managing digital information about a built asset such as building, bridge, highway, tunnel and so on.
The range of BIM 'maturity levels' are categorised as:
- Level 0: Unmanaged CAD (Computer Aided Design).
- Level 1: Managed CAD in 2D or 3D.
- Level 2: Managed 3D environment with data attached, but created in separate discipline models.
- Level 3: Single, online, project model with construction sequencing, cost and lifecycle management information.
In the UK, the Government Construction Strategy published in May 2011, stated that the '...Government will require fully collaborative 3D BIM (with all project and asset information, documentation and data being electronic) as a minimum by 2016'. This represents a minimum requirement for Level 2 BIM on centrally-procured public projects from April 2016.
This requirement for the adoption of BIM in the public sector has lead to an increase in uptake, meaning that the UK now ranks alongside Singapore, USA and Scandinavia (in particular Finland) in terms of BIM usage. Adoption of BIM in the UK is most common among architects and larger contractors, whilst there is less take up by services engineers, facilities managers and smaller contractors.
The 2012 nbs BIM survey found that 31% of respondents were using BIM. Whilst this showed an improvement on the previous year, rather worryingly it revealed that 30% of those surveyed only used 2D (rather than 3D) CAD, and 35% did not use CAD at all. The 2013 nbs BIM survey revealed that the figure had increased and 39% of respondents were using BIM. The NBS National BIM Report 2014 suggested that 54% had used BIM on at least one project, although 73% believed there was confusion about what BIM means. Rather surprisingly, the NBS National BIM Report 2015 showed a slight reduction in awareness and use, but this improved in the NBS National BIM Report 2016.
NBS have suggested that adopting BIM can cost a practice £10,000 per workstation (ref nbs: National BIM report 2012). However, this depends whether implementation is simply an exercise in buying hardware and software and then training staff to use it, or whether it is part of a wider process of business change. The justification for this cost is in the value that adoption of BIM brings to a project throughout its life-cycle. The BIM Task Group suggest that '...if successfully implemented, (BIM) will help organisations strip the waste from their processes which in many cases could be in the bandwidth of 20-30%' (ref BIM Task Group FAQ's).
Fundamentally, the purpose of BIM is to ensure that appropriate information is created in a suitable format at the right time so that better decisions can be made throughout the design, construction and operation of built assets. It is not about creating a 3D model for its own sake, and it is not an add-on process. BIM is fundamental to the way a project is set up and run.
It centres around the creation of employer's information requirements (EIR), which define the information that the employer wishes to procure in order to be able to develop and operate the built asset. Setting this out in a contract document ensures that appropriate information is created in a suitable format at the right time.
Very broadly, building information that might be required is categorised as:
- 4D (including time / programme information)
- 5D (including cost information)
- 6D (including facilities management information)
At level 2, building information models are likely to comprise a series of federated models prepared by different design teams, including model files, documents and structured data files containing non geometric information about the facility, floors, spaces, systems and components. Together these create a digital replica of the built asset that starts by representing design intent, but by handover, reflects what has actually been built and installed.
The creation of a geometric model as part of this process allows buildings to be conceived collaboratively and tested virtually, before they are built and operated for real. This should reduce the problems that are encountered in construction and occupation. See clash avoidance for more information.
These models are created from a series of objects. Each object is defined only once and then placed in the model in multiple locations as required. If the object is then changed, these changes will appear throughout the model. This makes models automatically consistent and reduces errors. See parametric modelling for more information.
The common data environment (CDE), is the single source of information for the project, used to collect, manage and disseminate documentation, the graphical model and non-graphical data for the whole project team. Creating this single source of information facilitates collaboration between project team members and helps avoid duplication and mistakes.
According to the NBS National BIM Report 2016, the most popular drawing tools are:
- Autodesk Revit (Architecture/Structures/MEP) 31%
- Graphisoft ArchiCAD 19%
- Nemetschek Vectorworks 15%
- Autodesk AutoCAD LT 12%
- Autodesk AutoCAD 12%
- Other 5%
- Bentley Microstation 3%
- Trimble Sketchup 1%
- Bentley Building Suite 1%
- Nemetschek Allplan 0%
 Protocols standards and tools
- PAS 1192-2 Specification for information management for the capital/delivery phase of construction projects using Building Information Modelling.
- PAS 1192-3 Specification for information management for the operational phase of construction projects using building information modelling.
- CIC BIM Protocol. This establishes specific obligations, liabilities and limitations on the use of building information models and can be adopted by clients to mandate particular working practices. It can be incorporated into appointments or contracts by a model enabling amendment.
- Uniclass2015. A classification system that can be used to organise information throughout all aspects of the design and construction process.
- Industry Foundation Classes (IFC). The standard data format facilitating interoperability between different software systems.
- COBie (Construction Operations Building Information Exchange). A spreadsheet data format for the publication of a subset of building model information focused on delivering building information (rather than geometric modelling), such as; equipment lists, product data sheets, warranties, spare parts lists, preventive maintenance schedules and so on. COBie presents information in a more accessible format, so that it is easier to use and re-purpose. This is essential to support operations, maintenance and asset management once the built asset is in service.
- BIM Toolkit. Developed by NBS, and offering a Digital Plan of Work to help define roles and responsibilities for preparing information and a verification tool to identify correctly classified objects and confirm that required data is present in the model.
 Related articles on Designing Buildings Wiki
- BIM and facilities management.
- BIM articles.
- BIM execution plan.
- BIM glossary of terms.
- BIM level 2.
- BIM maturity levels.
- BIM resources.
- Construction Operations Building Information Exchange (COBie).
- CIC BIM Protocol.
- Collaborative practices.
- Common data environment.
- Data drops.
- Employers information requirements.
- Federated building information model.
- Global BIM market.
- Government Construction Strategy.
- Government Soft Landings.
- Industry Foundation Classes.
- Information manager.
- Level of detail.
- PAS 1192-2:2013.
- PAS 1192-3:2014.
- Soft landings.
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