Within architecture, engineering and construction (AEC) industry, talk about digital transformation is currently heavily focused on ‘digital twins’ and the ‘Golden Thread’. Steve Salmon argues that BIM is a strong foundation for delivering both, so long as reality capture is incorporated into the process.
Interest in ‘digital twins’ in the architecture, engineering and construction (AEC) sector has rocketed since about 2016. That was the year when BIM was supposed to ‘come of age’, with all major UK government-procured projects deploying what was then termed “Level Two BIM”. However, interest in BIM seemed to plateau at that point; surveys, by the UK BIM Alliance and NBS among others, suggest that BIM is not yet business as usual across the whole AEC sector. And amid the exhortations to digitise, ‘digital twin’ and ‘Golden Thread’ seem to have replaced BIM as the latest industry buzzwords.
Delivering a ‘digital twin’
As BIM momentum slowed after 2016, the UK government started to look beyond BIM, talking about digital twins. First, we had the National Infrastructure Commission’s report Data for the Public Good, in December 2017. Then, about a year later, the Centre for Digital Built Britain published the ‘digital twin’-defining Gemini Principles, after which the Digital Twin Hub was established.
The Gemini Principles defines a ‘digital twin’ as “a realistic digital representation of assets, processes or systems in the built or natural environment”, importantly adding that the digital representation is also connected in real-time to the physical twin, with data able to flow bi-directionally between the two. The digital model is thus updated by data outputs from the physical asset and can be used to make interventions in the physical asset’s operation and management. We also began to talk about there being a ‘national digital twin’ – where ‘twins’ of buildings and infrastructure could be interconnected to provide information for decision-making about complex system interfaces.
Other definitions of ‘digital twins’ abound. There are some technology vendors that suggest a 3D model is a ‘digital twin’, or that a navigable virtual reality rendition of a building is ‘a digital twin’. Model authoring and rendering applications and reality capture technologies such as laser scanning and photogrammetry can certainly help, but a ‘digital twin’ is an outcome arising from deployment of the BIM process.
Deploy BIM – get a digital twin
For me, BIM is largely about managing digital design and construction processes while a ‘digital twin’ is about reuse of information for ownership and operation of the asset.
If you have a comprehensive BIM approach, including as-built reality capture processes, then BIM effectively delivers a digital twin for free.
It is important to include reality capture in the BIM process. First, no matter how detailed the design process and no matter how faithfully the constructors follow the design, there will often be changes: differences between what was intended and what was actually fabricated or installed. Second, what was actually fabricated or installed is often quickly obscured: structural elements and building services components are often hidden in floors, walls and ceilings; congested plant-rooms may prevent easy inspections. As-built reality capture provides a way to accurately record exactly what was built where. PointFuse software is then used to create a 3D model of what is there with the same data structure and information as the original design model.
This is valuable information for the building owner/operator. A 2004 US study conservatively estimated that not having ready access to accurate information about facilities required owners to spend $0.20 per square foot per annum to resurvey their buildings. An effective BIM process captures accurate and reliable information that avoids that need, and also enables compliance with emerging regulatory requirements.
Capturing the ‘Golden Thread’
In the UK, the Grenfell Tower fire disaster has led to a major rethink of building safety requirements. Dame Judith Hackitt recommended that building owners should be obliged to create and maintain a “Golden Thread”. She called for ‘digital by default’ record-keeping covering the design, construction, occupation and any future refurbishment of high-rise buildings, with data to be captured in open and non-proprietary formats with proportionate security controls. The Building Safety Bill currently going through Parliament will enact this recommendation – which effectively calls for a ‘digital twin’ – and the AEC industry is already grappling with the practicalities of delivering the Golden Thread of building information.
Going forward, this will be relatively straightforward for new-build projects where BIM, including as-built reality capture, creates the digital foundations of that Golden Thread. However, it will be more challenging where records may need to be retrospectively created for many existing buildings. At PointFuse, we are already looking at how to do this, with our scanning technology and building survey colleagues.
Retro-BIM
Our workflow is to walk a building with a mobile scanner to capture a point cloud. That data is then imported into PointFuse so that it can optimised for visualisation and classification in a 3D environment by a surveyor. Geometrical representations of walls, floors, ceilings, cables, pipes, fire doors, sprinklers, etc, are annotated with relevant information (perhaps also using any plans or other historic documents that may exist) about their material and condition. This baseline information can then be updated as further investigations, replacements, repairs or maintenance are undertaken. The process captures what is actually there, so that owner-operators, regulators, insurers and other stakeholders can then monitor changes over time.
The initial post-Grenfell measures are mainly focused on fire safety in high-rise residential buildings, including student accommodation, hotels and hospitals. However, better and more consistent practices will, I think, quickly extend to many other building types where the safety and wellbeing of occupants needs to be ensured. The approach could also be applied to other safety-related matters – for example, the June 2021 collapse of the Surfside condominium building in Miami Florida suggests that we might need to create and maintain a Golden thread about structural safety. Add water ingress, asbestos, Legionnaires Disease, lift maintenance – there are many challenges where accurate surveying and record-keeping can help with efficient and timely decision-making.
Better information management
As I said earlier, a ‘digital twin’ is something that can be used to provide regularly updated and accurate information for decision-making about physical assets. This is not just something that is needed for regulatory requirements or for operation and maintenance. It can also be used when owner/operators need to make strategic commercial decisions: for example, a factory owner might need to plan out a new production line, or a warehouse operator may want to vary parcel sizes.
Such benefits all flow from the alternative definition of BIM: Better Information Management. As an industry we need to be better at capturing, creating, sharing and using information that adds value across the whole life of our built assets (much like the service history of a car adds to its second-hand value). While I am an enthusiast for technologies, our focus should not be on the technologies, but on the information and decisions they help to deliver, and on the economic, social and environmental outcomes that flow from developing a better, safer and greener built environment.
