The key BIM terms you need to know

There are lot of new technical terms and keywords being used in connection with BIM, the average construction industry worker could be forgiven for being confused by the jargon. With that in mind, the following is a list of the some need-to-know BIM terms, and their definitions.


  1. 4D, 5D, 6D-

First there was 2D CAD, then 3D CAD – now there are extra dimensions to refer to the linking of the BIM model with time, cost and schedule-related information (Facility Management)

  1. Asset Information Model (AIM), Building Information Model (BIM), Project Information Model (PIM)

Not only is there the ‘Building’ information model, but the ‘Asset’ information model – which is the name given to the same model post-construction, i.e. supplemented with the data needed to assist in the running of the completed asset. Note that ‘asset’ can also refer to civil engineering and infrastructure work.

  1. BIM execution plan (BEP)

BIM Execution Plan is created for managing the delivery of the project. This in turn is split into a ‘pre-contract’ BEP, in response to the Employer’s Information Requirements (in other words, comparable to ‘contractor’s proposals’ in a Design & Build contract) and a ‘post-contract’ BEP which sets out the contracted delivery details.

  1. Clash rendition

Rendition of the native-format model file is be used specifically for spatial coordination processes. Used to achieve clash avoidance or for clash detection (between, for example structure and services) between Building Information Models prepared by different disciplines. The key benefit is in reducing errors, and hence costs, pre-construction commencement.

  1. Common Data Environment (CDE)

This is a central information repository that can be accessed by all stakeholders in a project. Whilst all the data within the CDE can be accessed freely, ownership is still retained by the originator. Cloud storage is a popular method of providing a CDE, although it could also be a project extranet.

  1. Construction Operations Building Information Exchange (COBie)

COBie is a data schema which is delivered in a spreadsheet data format, and contains a ‘subset’ of the information in the building model (all except graphical data, and hence a subset of IFC), for FM handover. It was originally devised by the US Army Engineering Corps. Over the course of a project, data can be added to it from a range of sources (besides CAD programs), relating to brief, design, construction, operation, refurbishment or demolition, as the case may be. The Government’s Level 2-mandated requirement is for COBie-compliant information exchange.

  1. Data Exchange Specification

A specification for electronic file formats that are used for the exchange of digital data between different BIM software applications, thereby facilitating interoperability. Examples include IFC and COBie. PAS 1192-2 outlines information exchange activities.

  1. Information Delivery Manual (IDM)

To make BIM effective, information needs to be:

  • Made available when it is needed and
  • To a satisfactory quality.

This can be achieved by using an Information Delivery Manual, that identifies the various construction processes, and the information required at each stage.

  1. Level 0 BIM, Level 1 BIM, Level 2 BIM and Level 3 BIM

The move to ‘full’ collaborative working via distinct and recognisable milestones, in the form of ‘levels’. These have been defined within a range from 0 to 3, and, whilst there is some debate about the exact meaning of each level, the broad concept is:

Level 0: No collaboration. 2D CAD drafting only. Output and distribution is via paper or electronic prints, or a mixture of both.

Level 1: A mixture of 3D CAD for concept work, and 2D for drafting of statutory approval documentation and Production Information. CAD standards are managed to BS 1192:2007, and electronic sharing of data is carried out from a common data environment (CDE), often managed by the contractor.

Level 2: Collaborative working – all parties use their own 3D CAD models. Design information is shared through a common file format, which enables any organisation to be able to combine that data with their own in order to carry out interrogative checks on it. Hence any CAD software that each party used must be capable of exporting to a common file format.

Level 3: Integrated working between all disciplines by using a single, shared project model which is held in a common data environment. All parties can access and modify that same model, removing the final layer of risk for conflicting information.

  1. Level of detail (LoD), Level of information (LoI)

‘Level of definition’ is defined in PAS 1192-2 as the “collective term used for and including ‘level if model detail’ and the ‘level of information detail’”. ‘Level of model detail’ is the description of graphical content on models at each of the stages defined, for example, in the CIC scope of services. The ‘level of model information’ is the description of non graphical content in models at each of these stages. BS 8541 defines level of detail for BIM objects as:

  • Schematic
  • Concept
  • Defined

Level of information defines how much detail is required at each of these stages – i.e. whether spatial, performance, standard, workmanship, certification etc.

  1. Life-Cycle Assessment (LCA)

Life-cycle assessment (LCA, also known as life-cycle analysis) is a cradle-to-grave environmental impact assessment for built assets, in terms of materials and energy. The energy and materials used, along with waste and pollutants produced as a consequence of a product or activity, are quantified over the whole life cycle.

  1. PAS 1192

The PAS 1192 framework sets out the requirements for the level of model detail (the graphical content), model information (non-graphical content, such as specification data), model definition (its meaning) and model information exchanges:

  • PAS 1192-2 deals with the construction (CAPEX) phase, and specifies the requirements for Level 2 maturity; sets out the framework, roles & responsibilities for collaborative BIM working; builds on the existing standard of BS 1192, and expands the scope of the Common Data Environment.
  • PAS 1192-3 deals with the operational (OPEX) phase, focussing on use & maintenance of the Asset Information Model, for Facilities Management.
  • BS 1192-4 documents best practice for the implementation of COBie.
  • PAS 1192-5 is currently under development, and will cover security of data.

About AEC digital solutions LLC

Headquartered in USA, AEC Digital Solutions LLC is a leading outsourced service provider in CAD and BIM (Revit and Bentley) having a global presence and operations in India. It offers BIM Modelling and support services such as BIM Studio, Virtual Design & Construction, BIM Content Creation, Commercial Kitchen Layout & Content Creation, Scan to BIM, BIM Integration and Documentation services. The team comprises of seasoned professionals – Architects and Engineers, having an average BIM experience of 8 years.