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BIM in construction

Building Information Modelling (BIM) is the process of generating and managing data about the building, during its life cycle. Typically BIM uses three-dimensional, real-time, dynamic building modelling software to increase productivity in the design and construction stages.

NBS Information Specialist Michael Smith looks briefly at the current state of play in Building Information Modelling.

Introduction

Building information modelling covers geometry, spatial relationships, light analysis, geographic information, quantities and properties of building components. BIM data can be used to illustrate the entire building life cycle, from cradle to cradle; quantities and properties of materials can be extracted easily and the scope of works can be easily defined. Furthermore systems, assemblies and sequences can be shown in a relative scale to each other and relative to the entire project.

BIM goes far beyond simply switching to a new software. It requires changes to the definition of traditional architectural phases and far more data sharing than architects and engineers are used to. It is able to achieve these improvements by modelling representations of actual parts and pieces being used in the construction process, representing a major shift from traditional computer aided design.

The interoperability of the model requires that drawings, master building specifications, standards, regulations, manufacturer product specifications, cost and procurement details, environmental conditions, (emissions data) and submittal processes all work together. The whole process is about different information resources feeding into the documentation, which then becomes a necessary part of the model.

BIM is far more than 3D CAD modelling; it is a rich information source containing far more than geometric information. Software is the interface to a building information model; rich information content is its body and soul.

Proponents anticipate that managed BIM will reduce the information loss associated with handing a project from design team, to construction team and to building owner/operator, by allowing each group to add to, and reference back to, all information they use/create during their period of contribution to the BIM model.

How does BIM work?

A BIM system can, of course, produce drawings but is no longer based on lines, shapes and text boxes but on data sets that describe objects virtually, in the same way that they will be handled physically. However, the real difference is in the true interoperability and the capability for proper integration, allowing the inputs of the various professionals and specialist to come together in the Building Information Model.

On a technical level the Industry Foundation Classes (IFC/ifcXML) are an open specification for Building Information Modelling and are used to share and exchange BIM in a neutral format among various software applications. Green Building XML (gbXML) is an emerging schema focused on green building design and operation and is used as input in several energy simulation engines. gbXML is one of a large number of building energy simulation tools available on the market. When choosing which simulation tool to use in a project, the user must consider the tool's accuracy and reliability, considering the building information they have at hand, which will serve as input for the tool.

BIM in the UK

In the UK, CPIC, who are responsible for providing best practice guidance on construction production information, has proposed a definition of Building Information Modelling for adoption throughout the UK construction industry. The proliferation of interpretations of BIM currently hampers the adoption of a working method to improve the construction industry and the quality and sustainability of the deliveries from the design and construction team to clients.

The RIBA, CPIC and BuildingSmart jointly proposed a definition of BIM for the UK construction industry, as a starting point for discussion and refinement. It is:

'Building Information Modelling is digital representation of physical and functional characteristics of a facility creating a shared knowledge resource for information about it forming a reliable basis for decisions during its life cycle, from earliest conception to demolition.'

Benefits of BIM

Managing building information using a building information model can lead to substantial cost savings, from design and construction through to maintenance.

The model saves time and waste on site, and extra coordination checks are largely unnecessary; the information generated from the model will lead 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, changes are automatically coordinated across the project and information generated is therefore of high quality.

Information Technology is an integral part of today's commerce, and transferring information from designers to the producers/constructors is an example where, with the availability of modelling software, the tools are in place. We simply need to understand the process for using them.

BIM for existing buildings

There have been attempts at creating a BIM for older, pre-existing facilities. These generally reference key indicators, such as the Facility Condition Index (FCI). However, the validity of these models will need to be monitored over time; trying to model an existing building would require numerous assumptions about design building standards and codes, construction methods and materials available at the time of construction.

Future of Building Information Modelling

BIM is the future of construction and long term facility management but there is still much confusion about what exactly it is and how it should be utilised and implemented. BIM is a relatively new technology in an industry typically slow to adopt change. Yet many early adopters are confident that BIM will grow to play an even more crucial role in building documentation.

BIM provides the potential for a virtual information model to be handed from Design Team (architects, surveyors, consulting engineers, and others) to Contractor and Subcontractors and then to the Owner, each adding their own additional discipline-specific knowledge and tracking of changes to the single model. The result greatly reduces information losses in transfer. It also prevents errors made at the different stages of development/construction by allowing the use of conflict detection where the model actually informs the team about parts of the building in conflict or clashing. It also offers detailed computer visualization of each part in relation to the total building.

As computers and software become more capable of handling greater amounts of information, this will become even more pronounced than it is in current design and construction projects.

Michael Smith is a member of the Construction Information Service editorial team. He is a mechanical engineering and building services specialist, chartered information specialist (MCLIP) and chartered environmentalist (CEnv).

Further Information

What BIM is and how it is being used?
Research presentation by Dr Stephen Hamil, Head of BIM at NBS, into the use of BIM by UK construction professionals

Integrated Project Working - definition of Building Information Modelling (BIM)
Keith Snook, RIBA Director of Research and Technical, has produced a paper to help provide a definition of BIM for adoption throughout the construction industry.
http://www.riba-knowledgecommunities.com/

Business value of BIM - McGraw-Hill Construction SmartMarket Report (2009)
Study of BIM adoption in North America and the ways in which users are experiencing business value and generating ROI
http://bim.construction.com/

Green BIM: How BIM is contributing to green design and construction - McGraw-Hill Construction SmartMarket Report (2010)
Study of how the tools and processes of BIM are contributing to higher performing buildings, more environmentally responsible construction practices and achievement of green objectives during operations and maintenance.
http://construction.com/market_research/FreeReport/GreenBIM/

Business value of BIM in Europe - McGraw-Hill Construction SmartMarket Report (2010)
Study of how BIM is being adopted and implemented in three major European economies: France, Germany and UK. Includes comparisons to North American data collected as part of earlier BIM research.
http://bim.construction.com/research/FreeReport/BIM_Europe/

Construction Project Information (CPIC)
Promoting collaborative working within the construction industry.
http://www.cpic.org.uk/en/

Industry Foundation Classes (IFC/ifcXML)
Official source of all information about the technical specifications issued by buildingSMART International and of the supporting interoperability implementation programmes.
http://www.buildingsmart-tech.org/

Green Building XML (gbXML)
gbXML open schema helps facilitate the transfer of building properties stored in 3D building information models to engineering analysis tools
http://www.gbxml.org/