What is the difference between BIM and Digital Twins?

The terms BIM and digital twin occupy a similar space within the built environment and can sometimes be confused with one another.

One thing they have in common is that they are both at the core of building life cycle management.

As their importance in the sector increases, the UK BIM Alliance has prepared definitions to clarify the relationship between the two.

What is BIM?

BIM stands for Building Information Modelling; however, the UK BIM Alliance prefer to use the term Better Information Management. It is the process of delivering structured data about built environment assets through their lifecycle. This enables the ‘use of a shared digital representation of a built asset to facilitate design, construction and operation processes to form a reliable basis for decisions.’

In the UK, the BS EN ISO 19650 suite is available as part of the UK BIM Framework and includes guidance on implementation. It defines a combined CAPEX and OPEX process allowing for the management and use of information throughout the lifecycle of assets and is summarised below:

• Client considers the use case and purpose for a particular trigger event (which may be operational (e.g. planned, or reactive maintenance), or maybe a new development project).
• Client defines what information is needed and to what standards (incl. cyber/physical security).
• Client appoints the team(s) at appropriate time with the relevant contract amendments to cater for data as a deliverable including acceptance criteria.
• Team plans for the information delivery.
• Team delivers the information.
• Information is verified and validated.
• Accepted information is handed over to the client as a set of information containers forming the information model for this appointment, which can then be used to support the originally determined decisions/purpose.
• The client ensures that future CAPEX project information, and further OPEX information is combined on an ongoing basis, and as appropriate, into the overall integrated information model(s) for the asset, through the entire lifetime of the asset.
• The integrated information model(s) continue(s) to be used and updated during refurb or demolition.

What is a Digital Twin?

The Centre for Digital Built Britain (CDBB) published the Gemini Principles in 2019 offering the following definitions:

1. A dynamic model of an asset, with input of current performance data from the physical twin via live data flows from sensors; feedback into the physical twin via real-time control.

2. A static strategic planning model of a system, with input of long-term condition data from the physical twin via corporate systems; feedback into the physical twin via the capital investment process.

The aim of the CDBB National Digital Twin programme is to create an ecosystem of digital twins that open up the opportunity to achieve greater value by using data. For the UK Government, the National Digital Twin enables a greater understanding of the UK’s infrastructure and by its very nature, it will include built assets in one form or another most of the time. Leaders of the programme have declared that BIM is a necessary foundation of a built environment digital twin.

The key differentiator between digital twins and ‘static’ BIM deliverables is the addition of dynamic ‘right-time’ data.