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BIM – Past, present and future.. what is 6D?

What is BIM?

Building Information Modelling (BIM) is a 3D digital representation of a building founded on open standards for interoperability and through its comprehension of spatial relationships.

Where did BIM start?

The ideas and concepts relevant to BIM have been apparent since the earliest days of computing with previous evolutions of BIM including computer models for buildings in the 1970’s. An elementary foundation for a BIM which has a close connection with architectural design and engineering practices is the requirement for graphical user interface and the description of three-dimensional (3D) geometry.

Since the development of these early technologies there have been various university and industry collaborations to further the development of BIM.

What are the multiple “dimensions” of BIM?

By the year 2000, a program called “Revit” was developed which made object oriented programming possible. The ability to assign a time attribute to individual components allows construction schedules to be developed based on the BIM (known as the “fourth-dimension” or 4D). These 4D models are used to simulate the construction process as well as allow real-time cost estimation and material quantity take-offs.

Various uses for BIM tools such as client decision making, design and engineering, pre-construction and estimating, scheduling, constructability analysis, construction coordination, and post-construction. Efforts are under way to help standardise the use of BIM and related tools to help the industry streamline sharing of project information and therefore reduce duplication while helping stakeholders to avoid issues and conflicts on projects.

Additional tools have been integrated with BIM which are considered additional “dimensions”. Table 1 below summarises the differences between the capabilities of 3D, 4D, 5D and 6D BIM systems. Table 2 provides a matrix that demonstrates the various uses of the different model types.

Table 1 – Various types of BIM models and their respective capabilities 

Model Type Model Description
3D Models
  • Building models that provide the perception of depth
  • Building Systems Coordination
  • Architectural / Structural, MEPF Clash Detection
  • Construction Sub-Trade Coordination
4D Models


  • Combines 3D models with the appropriate scheduling data
  • Model Based Construction Simulation
  • Project and Manpower Scheduling
5D Models
  • Combines 3D models with the appropriate cost data
  • Model-based Quantity Take-offs and Estimating
  •  Performance Based Value Engineering
nD (or 6D) Models
  • Combines 3D models with the life cycle management data
  • Energy Life Cycle and Daylighting Performance Modeling
  • Virtual As-Builts with Hyperlinked product data, warranties, O&Ms, and manufacture’s web sites

Table 2 – Various types of activities and their use of respective types of models

  Model Type
Activity Description 2D 3D 4D 5D nD
Client decision making    
Design and engineering    
Pre-construction and estimating    
Constructability analysis        
Construction coordination