Origin of the Concept

The Digital Twin concept, which has been gaining ground in various domains for the past ten years, has its roots in the aerospace industry.

During the Apollo 13 space mission, to bring back to Earth the damaged spacecraft, NASA specialists created its mathematical model, which, combined with the measurement's signals received from the real object, allowed them to simulate the behaviour of the Apollo 13 and elaborate appropriate control algorithms.

This rescue operation is often considered the first case when the digital twin concept was used for the first time. 

Generally speaking, the idea consists of creating a mathematical model of a technical object, first used in the design phase for preliminary calculations.

Then later, at the operation phase, this model (digital twin), in combination with the readings of sensors coming from the real object (physical twin), is used locally or remotely for simulating its behaviour and optimizing control algorithms.

 

Digital Twin of Residential and Commercial Buildings

At first glance, the rationale for such an application might raise some doubts. 

Without diminishing the complexity of a spacecraft, we see that well-known mathematical equations describe its movements when describing its dynamics. 

While what happens in a building, with people moving from one room to another, switching on and off various appliances, seems more chaotic and less predictable by any mathematical model. 

In addition, the construction of residential or commercial buildings may not benefit from the same financial ease as a project consisting of creating and launching an expensive piece of equipment stuffed with the most advanced technologies into outer space.

Well, let’s say it is not entirely accurate.

 

Rationale for Digital Twin 

First, the relative simplicity of the mathematical modelling of the spacecraft is debatable as the digital twin usually goes beyond simple reproduction of basic movements and includes a detailed description of numerous technical systems and elements of the spacecraft.

Any mathematical model will, by default, be inaccurate. But the essence and strength of the digital twin is that the simulation results are combined with the readings of sensors received from the real object.

This allows for improving the mathematical model and adjusting simulation results to make operational decisions. 

Second, the widespread IoT created fertile ground for the deployment of the digital twin by making collecting various measurements easier and more affordable.

Thus, the concept of a digital twin is applicable in the aerospace industry and other areas, particularly for managing residential or commercial buildings to increase their comfort and safety and reduce operational costs.

 

Digital Twin and BIM

Compared to the digital twin, BIM (Building Information Modelling) sets more prosaic goals, albeit today, thanks to the development of digital technologies, especially 3D visualization, this tool is widely used by architects.

An architect can create an interactive 3D model of the entire building using a library of 3D models of building materials and technical equipment, characterized by their shape and dimensions. And then evaluate its geometric characteristics in terms of comfort, aesthetic design, air quality, fire safety, etc. 

In turn, the digital twin is a virtual representation of the elements of a technical object and, in this case, a building, which provides both its static and dynamic characteristics. 

As the digital twin should also provide the geometrical features and is simply unthinkable without advanced visualization, BIM turned out to be a digital  technology helping to build a user interface and a virtual representation of the system elements, or to be more precise, of their “static” characteristics.

To date, some software tools already allow creating a 3D user interface for building management systems, taking the BIM model as a basis and supplementing it with the dynamic characteristics received from the IoT sensors. 

In this case, the user can navigate through the virtual model of the building and, by clicking on a particular element, can get its actual technical characteristics, both static and dynamic. 

 

BIM and IoT 

Often, this combination of BIM and IoT is already presented as a digital twin. However, in my understanding, this simplification significantly diminishes the idea of the concept.

Firstly, this combination of BIM and IoT would not be much different from the good old SCADA systems, except for more advanced visualization. 

And secondly, the basic idea of the digital twin is that the data provided should serve a purpose and, after processing, bring some added value to the user. Otherwise, this data will remain just a useless array of numbers. 

Therefore, besides BIM and IoT, the digital must include a specific layer of applications. 

Based on the mathematical model of technical systems and business processes occurring in the building, these applications are supposed to optimize its operation, reducing costs and making it safer, healthier and more comfortable. 

These algorithms can work either in automatic mode or in the "operator's advisor" format. 

By the way, leading providers of building management systems, such as Schneider-Electric, Siemens, and Johnson Controls, talk about an advisory layer as a distinctive feature of their systems.

 

Future Steps and Perspectives

The digital twin is still a young technology in the building management field with its roadblocks and reluctance of potential customers.

First, from the implementation point of view, this is still an expert area, with ad hoc developments instead of a banalized tool kit. Perhaps this new application domain would not go unnoticed by BIM developers, and we might see new BIM standards and 3D models that could easily integrate some mathematics and dynamic data in the coming years. 

That would make the digital twin technology accessible to a wider network of BMS providers and integrators. 

Second, and probably the most important, the future innovation should shape a bit better what we called earlier the application layer. 

Today we hear many complaints that this technology remains too foggy, and its benefits are unclear, especially when it comes to commercial videos and publications. I think the technologies available today provide various possibilities, but most of them are still untapped. 

Creating applications which would bring a real solution to fundamental pain points and needs of the building is not as easy as it could appear. This is a challenge for future innovations. 

In the coming years, it will be quite interesting to see how the digital twin will evolve, which of its functions will find their place in the market, and what would be BIM's role in this evolution.

 

This article was contributed by our expert Oleg Viter 

 

Frequently Asked Questions Answered by Oleg Viter

Q1. Does Digital Twin include Artificial Intelligence? 

Yes and No. 

No, if AI is understood as a machine intelligence capable of thinking and feeling like a human. 

Yes, if AI means application software capable of improving the operation of the physical twin. 

 

Q2. Is BIM the only techno suitable as a user interface for DT? 

No. GIS could be an alternative as well.