How can ‘digital twins’ connect and interact? Here, Mark Enzer, Chair of the Digital Framework Task Group (DFTG) discusses the purpose of digital twins, the national digital twin, and its possible futures.

We also chatted to Mark about all things digital twins in November last year, and you can listen to the podcast here.

This work forms part of our wider digital twins R&D project.

By Mark Enzer

Digital twins and why we need them

A ‘digital twin’ is a realistic digital representation of assets, processes and systems within the built environment. But what actually makes it a digital twin, rather than just any other model, is the two-way connection between the physical world and the digital world. Data from the physical world informs the digital twin. That can then be analysed and help generate insights to enable better decisions.Those decisions then drive better interventions which loop back and can be applied to the physical world. The core of it is a two-way connection between digital and physical.

Examples of digital twins

Formula 1 is a good example of a digital twin. Formula 1 takes live data from the car as it’s going around the track, helping to facilitate better decisions. Those decisions then inform not just race day strategies, but also the design modifications for the next Grand Prix, which helps improve the performance. So: the two-way connection between the physical and the digital.

Digital twins can enable us to run ‘what-if’ scenarios and develop detailed plans in the digital world before taking action in the physical world.

There are also some emerging examples within the built environment. For example, in a nuclear power station, modelling how best to move around radioactive material, where safety is obviously paramount. Digital twins can enable us to run ‘what-if’ scenarios and develop detailed plans in the digital world before taking action in the physical world. Digital twins can also work at a network or system level, improving operation and maintenance decisions, or resilience planning.

The concept of digital twins can be applied at different levels and over different time scales but at the core of it the idea is the same: you take data from the physical world, do something useful with it to drive decisions and make better interventions in the physical world.

What is the national digital twin?

We’re defining the national digital twin as an ecosystem of connected digital twins. We can see the value of individual digital twins – helping to make better operational, maintenance, investment and planning decisions. But we can see even more value in moving beyond that and connecting twins.

And this really all comes down to data sharing.

This becomes particularly important when data from one sector or organisation can impact or inform another. For example, the key physical connections between the energy sector and the transport sector demonstrates a scenario where it would be beneficial to share data across those sector boundaries.

This connection of twins will be most important in situations when many economic infrastructure sectors overlap – principally in the context of cities. A city is where all of these sectors meet. Sharing data between sector digital twins will be critical to facilitate cross-sector decisions for the benefit of the people in the city.

Developing the national digital twin

We can see the huge potential value in sharing data between digital twins to facilitate different and better decisions at system and sector level. Our aim is to help ensure digital twins can connect at this early stage in development – by having shared data, standards and frameworks – rather than retro-fitting interoperability further down the line.

The Gemini Principles

We’ve developed a set of principles – the Gemini Principles – that aim to guide the development of this national digital twin.

The Gemini Principles emerged through discussion with industry experts about values, which effectively become the ‘conscience’ of the national digital twin.

The Gemini Principles are value-based principles that will guide the national digital twin journey. We are addressing these values right up front – before we’ve even really started on technical issues about how you share data – so that the values are at the core. Technology will change but the values can remain throughout.

The National Infrastructure Commission’s report, ‘Data for the Public Good’ was the catalyst for the Gemini Principles, with the key driver of ensuring that outcomes will be for the public good. In other words, the national digital twin should be a network of ‘good twins’. It needs to be informed by values that we all ascribe to.

The Gemini Principles emerged through discussion with industry experts about values, which effectively become the ‘conscience’ of the national digital twin. The idea is that the principles will provide a framework to continually check against, to ensure the values are being adhered to. Technology will change rapidly but values should be persistent. If we have a values-based national digital twin it’s much more likely to turn out well.


There is strong feedback from industry – and others – against the idea of one massive monolithic model with some kind of heavy-handed top-down control. There is more support for the idea of something that’s connected, with appropriate control at a lower level – and facilitating connection so that an ecosystem of connected digital twins can grow organically.

That aligns with the way that the industry actually works. It’s about pragmatism as well as values: centralised top-down authoritarian control bears very little prospect of working. Whereas bottom-up, experience-driven, learning-by-doing and progressing-by-sharing just has the feel of something that is more likely to succeed.

Bottom-up v top-down

There are also risks at the bottom-up end of the spectrum, where there may be very little coordination. A fully Darwinian approach is likely to take longer to get to the right answer because the early dominant solutions are not necessarily going to be the best in the long run. While both the top-down authoritarian approach, and the unguided bottom-up evolution are both too extreme, taking elements from each approach could be useful.

In the top-down version, there is an advantage in industry experts steering the process from a national perspective. There are also advantages to the bottom-up Darwinian approach of learning-by-doing and having a practitioner-based approach to growing standards from experience. We’re aiming to get the best of both worlds, bringing experts and practitioners together.

What could a bad future look like?

There is a whole spectrum of potential ‘bad futures’ that we are aiming to avoid. And there are probably more ways of getting it wrong than getting it right. That’s why we need to put the energy and intellect into making it work. If we don’t unlock the value of data – that could be a bad future.

There is a risk of developing digital twins that are not able to connect with each other. While digital twins are valuable individually, without a framework of shared values and standards, interoperability would fail, which is at the heart of the national digital twin.

Societal benefits

The national digital twin is all about bringing benefits to society; seeing infrastructure as a platform for human flourishing and recognising that better decisions based on better data lead to better outcomes. A successful National Digital Twin Programme would enable all that. It’s not about geeky playing around with data; it’s about the positive economic, social and environmental outcomes for all.


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