A Glossary Of BIM

Technology can be a minefield of terms and acronyms. The platforms and technology related to BIM - the acronym representing Building Information Modelling - are certainly no exception.

We're keen to avoid using words that require insider knowledge to understand, so to help along the way, we've collected the most common BIM terms you're likely to come across in general usage and provided a clear explanation of their meaning.

Call it a BIM 'Crib Sheet' if you like...










Three dimensional drawings or models




A 3D model that includes a measurement of time and/or sequence




A 4D model with added information regarding cost





As above, but with information to aid facilities management after construction has finished and the lifecycle of the building as it progresses




All of the above levels, with the addition of data from sensors







A BIM Execution Plan (BEP) as described in the British Standards and Publicly Available Specifications (PAS): PAS 1192-2:2013 is a "plan prepared by the suppliers to explain how the information modelling aspects of a project will be carried out". It is an essential agreement from all parties regarding how they will all work together to collaborate and co-operate in the sharing of data.






Building Information Modelling: At a basic level, BIM is a process involving the generation and management of digital representations of physical and functional characteristics of places. Think 3D models, but with detail showing where wiring will be added, pipes placed and so on. See this video explaining BIM models in just three minutes.


BIM maturity































At the most basic, BIM can just be CAD (see below) models. At the most advanced; fully integrated, interoperable data able to be collaborated on by all parties. There are a number of definitions, but broadly speaking they fit into the following groups:

Level 0 - Unmanaged 2D CAD drafting, with electronic exchange of files, but no common standards or formats.

Level 1 - Managed 2D and 3D CAD files, containing models, objects, co-ordinates and structures following an agreed standard and able to be shared, but usually not collaborated on, via a standardised CDE (see below).

Level 2 - Managed 3D environment and data, able to be collaborated on by involved parties. May include 4D and 5D information. The UK government is pushing for all suppliers to meet Level 2 as a minimum and has various guidelines for minimum capability levels.

Level 3 - Still in its definition stages, it includes elements of all the previous levels and adds further expectations for: Whole life management of a building (including after its construction), measurement via 'Internet of Things' and the ability to integrate live with other BIM systems, allowing all systems to exchange and act upon common data. Level 3 may include 4D, 5D and 6D information.

A great article explaining the levels of BIM - and an expanded diagram of 'The Wedge' BIM maturity model below, developed by Mark Bew and Mervyn Richards - can be found here.

Image permission kindly granted by BIM+ 


The Wedge BIM diagram Lobster Pictures glossary of BIM






Computer Aided Design (CAD) is a blanket term used to refer to anything designed with the assistance of a computer, as opposed to being created by hand (such as an architect's technical drawings). CAD is often assumed to mean 3D (3 Dimensional) designs, but includes 2D design. 





A Common Data Environment (CDE) is a central location for the storage of project information. It could be as simple as a file dropbox, or a more advanced extranet. The important thing is that all parties have access to the files shared within it.






The Construction Operations Building Information Exchange (COBie) data format is a non-proprietary international data exchange standard, originally created by the United States Army. Its focus is on the tracking of assets, rather than geospatial data. COBie is a subset of IFC (see below).






The Industry Foundation Classes (IFC) specification in a non-proprietary data format designed to describe, exchange and share information. It was originally developed by a consortium formed by Autodesk; a provider of popular CAD software. It is an international standard: ISO/IS 16739.








The Level of Detail (LOD) describes the amount of information provided in the model. It is a measure of the refinement of data in a model.
In the UK, a LOD Level 1 model might contain only basic block objects for a concept model, whereas a Level 7 model will contain all accuracy information (geometry, location, shape etc) regarding the as-built, completed facility. Different services make use of the different levels of LOD and a Level 7 model is therefore not inherently 'better' than a Level 1.





Publicly Available Specifications: Shared public standards or specifications in rapid development. Developed in line with BSI guidelines, they are eventually considered for full BSI adoption.


Parametric modelling 




A parametric model is a digital model created from 'parameters'; a collection of rules and algorithms that influence the entire model. Importantly in a parametric model, if one rule or dimension is changed, then it influences the rest of the model. For example, if the width of a wall is increased, so are the corresponding dimensions of the floors, roofs and windows.






Uniclass is a unified classification system for project information structure, intended for all sectors of the UK construction industry. It is compliant with ISO 12006-2. Its classification of items of all scales, via consistent classifying tables, allows for the effective recording of items as disparate as steel beams, brickwork and even time lapse cameras.










Extensible Markup Language (XML) is a language used to 'mark-up' a document in a consistent format that is readable by both humans and machines. At a very basic level, an XML document could look like the following:
                <name>Bacon Sandwich</name>

The HTML language - used to create webpages - is one of many available variants of XML.



Downloadable BIM glossary PDFWould you like to know more?

To download the Lobster Pictures BIM Glossary crib sheet as a PDF, simply click below.


Free PDF download



For sources and for further reading, check out:


Designing Building Wiki - BIM Glossary of Terms

The BIM Hub Glossary

BIM Level 2 - Glossary

BIMPlus - Pocket Phrasebook

B1M BIM for Beginners 


Would you like to subscribe?