Building Information Modelling (BIM) and digital twins are two important technological concepts that can, at times, be considered quite separate or be used interchangeably in the buildings sector. Both concepts could be defined as “a digital representation of assets, processes and systems in a physical space,” yet they tend to be used by very different people and in different stages of the building’s life cycle. In this research note, we consider the similarities and differences of these concepts, to discover where BIM ends and the digital twin begins.
On the surface, you could say that BIM is more of a design and construction tool, and digital twins are focused on the operational phases of the building life cycle. While this is true to a certain extent, each concept has the potential to do it all, so why has each concept found its niche rather than one dominating the whole field? The answer to this lies in their intention rather than their technical capacity, as each technology fills the purpose they were designed for in an evolving building environment.
The history of BIM actually goes back to the 1970s when it could also be called a Building Description System (BDS). The initial hypothesis was that such a system would be important to contractors of large projects for both a visual and quantitative model of the build, and would foster better materials ordering and scheduling. The modern incarnation of the term came about in the early 2000s when the likes of Autodesk, Bentley Systems, and others began developing the direct predecessors of the BIM software that is used today.
“The early hypothesis for BIM holds true. Even today, leading providers of BIM software appeal to AECs (architects, engineers, and contractors) by explaining the cost-saving benefits of having a central point of building reference in a 3D digital model,” writes Sandy Mangat, Director of Marketing for digital twin solution providers, ThoughtWire. “BIM is tuned for collaboration and visualization during design and construction, not operations and maintenance. The intent of BIM is not to create a living breathing model of an operational building but to help architect and construct the building.”
“Digital Twins”, on the other hand, is a more modern term that transcends buildings. Digital twins can be applied up to the city scale and right down to the machine scale by using sensors and AI/ML to monitor all the moving parts and create a living breathing digital replica of whatever it is sensing. For buildings, digital twins can utilize all structural and sensor data to create a real-time model of every aspect of the building, from the flow rate of pipes to the location of people as they move around the space. Therefore, BIM data can be a key input for a digital twin, but BIM alone does not provide the insight required to optimize building operations.
“In some ways, a building’s digital twin can be seen as the logical expansion of the BIM concept, which is used to enable improved planning, collaboration and data visualization of a building during the design and construction phase. With the digital twin taking over to manage real-time ongoing operations and maintenance once the building has become operational,” explains our latest buildings IoT report. “Indeed, a fundamental foundation for the development of an accurate digital twin model of a building is the construction plans and data contained within the BIM model.”
Digital Twins & BIM in Tandem?
The difference between the two concepts was highlighted in 2020, when BIM-leader Autodesk released their digital twins service for buildings, Tandem, and again last year when it added facilities monitoring applications. Tandem utilizes BIM data but can also process and visualize the data that is streaming from building sensors to create a digital replica of the building in real time. It essentially uses the same data as BIM to create a structure to the digital building but Autodesk has also given it the ability to read all kinds of data that flow from the various sensors around the building.
“Tandem can read practically any digital format, whether it be DWG files, Revit models, PDFs and more, allowing it to effectively look at the whole picture, as it were. Instead of having to look at DWG files in AutoCAD, Revit files in Revit and PDFs in Acrobat, you can look at the whole building—inside and out—through the Tandem interface,” says Roopinder Tara, director of content at Engineering.com. “With active facility monitoring on top of Tandem, the BIM model can be like the twin that senses what its sibling is feeling even though they are separated.”
Autodesk’s venture into digital twins and facilities monitoring is a strong sign of the future trajectory of this discussion, a future that is likely dominated by digital twins at every phase of the building’s life cycle. In the short to medium term, BIM will continue to be a growing force in design and construction as governments around the world mandate and incentivize its use. However, as the design and construction teams take a more holistic view of projects and demand more data on how a building is used, digital twins designed to model everything will take center stage.
“If trends in commercial real estate continue to gravitate towards understanding occupants and competing on workplace experience, the Digital Twin will certainly supersede BIM software even at the design and build phase of an asset’s life cycle,” continues Mangat in an article on IoT for All. “As we begin to build things with people and flexibility in mind, our building information models will also need to evolve to include behavior patterns of people and space design that accommodates their wellness. BIM alone cannot achieve these outcomes.”