In our recently granted Horizon 2020 project Ashvin, we defined a digital twin as a digital replica of a building or infrastructure system together with possibilities to accurately simulate its multi-physics behaviour (think of structural, energy, etc.). Additionally, digital twins provide possibilities to represent all important processes around the building or infrastructure system throughout its product development lifecycle. These processes include evolving design information (as-designed vs. as-built) and an accurate description of all relevant construction, as well as, maintenance activities. The technical enabler for such digital twin representations is the internet of things (IoT) that allows establishing connections between real-time data coming from sensors and cameras as to establish a close correspondence of the physical entities and processes with their virtual representation. This definition is similar to the definitions provided by others, such as the one provided by for example Sacks et al. (2020) – https://doi.org/10.1017/dce.2020.16.
A closer look at these definitions, however, reveal the inherent danger of blurring technical possibilities with the realities of engineering design work and the constraints that are imposed on engineering by the boundaries of human cognition. The technical possibilities we have nowadays in terms of increasing the sophistication and depth of models representing products and their behavior is growing quickly. At the same time, we are more and more able to fuse and combine different data-driven and physics based models with each other in ways that would have not been computational possible just a number of years earlier. What is missing from technically driven definitions is however a clear focus on how an increase in model complexity can support engineers.
Reflecting some more, the notion of the ‘twin’ of the real world that exists in the digital might be ill chosen. After all, engineers establish models as simplified and highly abstracted representations of the reality so that they can cognitively deal with reality’s complexity. Instead of ‘accurately simulating the multi-physics behavior’ and ‘representing all important processes’, engineers are probably better supported by models that are supported by simplified simulations of the multi-physics behavior and by the representation of very few processes. Of course, all with the aim to support engineers within their limited cognitive abilities. But also from the utilitarian understanding that a simpler model that allows for similar understanding, is superior to a more complex model.
To account for this aspect, it might be appropriate to start technical research and development efforts from a solid and in depth empirical understanding of engineering work. From this understanding clear requirements can be derived, not only in terms, of what needs to be modeled, but equally important how abstract these models need to be for allowing engineers to still come to creative conclusions within their cognitive abilities.
To allow for such a development approach, the strategy we will follow therefore on Ashvin is a clear focus on how engineers can impact the productivity, resource efficiency, and safety of construction processes within different phases of the design and engineering life-cycle. From this we derived a number of very specific applications for supporting engineers (we call this the Ashvin tool kit) and drive all digital twin related development work based on the requirements for these applications. The next three years will show how successful we can be with such an approach to achieve our envisioned impact. The project’s website should be online soon at www.ashvin.eu.
To design, plan, and execute a building renovation, engineers need to not only understand the building itself, but also need to know quite some about the building’s environment. Knowledge about the environment is already required in the early stages of building condition assessment. For example, to plan drone flights round a building it is important to know whether there are trees of other objects around that would inhibit the drone flight. To evaluate different design options later on in the process with respect to the energy and occupant related performance knowledge about the local weather conditions or objects that might provide shading is required. During the execution one of the most important aspects that need to be accounted for is accessibility.
The above are only a couple of examples of the required knowledge. On our projects, more often than not, this knowledge is not systematically managed using our existing information models. To overcome this problem, in her research within the European BIM-Speed project Maryam Daneshfar explored the knowledge that engineers require to for renovating buildings. She formalized her findings in an ontology that is freely available here and discussed in a preliminary conference paper. I am sure publications about the ontology will soon follow in scientific journals. I will keep you posted.
Design optimization tools become readily available and easy to use (see for example Karamba or Dynamo. It is not surprising that studies exploring these tools are exploding. Many examples exist that illustrate how to design optimization models and execute optimizations. Often, however, these studies fail to provide the true impact that was expected in terms of improving the (simulated) performance of the engineering design. Showing that the deflection of a structure could be reduce by a centimeter or the material utilization used for the structure was reduced by some percent remains of course an academic exercise that can provide little evidence on the engineering impact of optimization technologies.
As we move forward in this field of research, we need to develop more studies that move away from simply showing the feasibility to apply relatively mature optimization methods towards formalizing optimization problems that matter. Finding such problems is not easy as we cannot truly estimate the outcomes of mathematical optimizations upfront. Whether a specific impact can be achieved can only be determined through experimentation – a long, labor extensive and hard process.
Even worse, identifying relevant optimization problems through a discussion with experts is difficult. The outcomes of each design optimization needs to be compared with the solution an expert designer would have developed using his intuition and a traditional design process. Hence, working with expert designers to identify problems might be tricky. After all they are experts and probably already can come up with pretty good solutions. It seems as one would rather need to identify problems that are less well understood, but still relevant. These problems might also be scarce as relevant problems are of course much more widely researched.
In the end, I think we need to set us up towards a humble and slow approach. An approach that is time consuming, that will require large scale cooperation, and needs to face many set-back in terms of providing an impact that truly matters. Maybe this is also the reason why a disruption of design practice is not yet visible. Until we will be able to truly understand how we can impact design practice with optimization we will still need to rely on human creativity and expertise for some time to come. (not saying that we should stop our efforts.
In the last years I was working with a lot of organizations, trying to explore how to better integrate advanced building performance simulation into the design and engineering processes for buildings. The struggle often is to figure out in what detail simulations are helpful during different stages of design. I have been working with companies that targeted very early decision making to support real estate developers all the way to companies that provide sophisticated consultancy in very detailed design phases. For me results are not conclusive and I really would like to do much more detailed and structured research. The farthest we are coming with our insights is in the area of supporting the renovation of buildings in two large EU funded research projects (P2Endure and BIM-Speed). Here we suggest that detailed building performance models of the existing buildings need to serve as a first step in the design process. These behavioral digital twin can then form a baseline to explore different building renovation options. A key within these efforts is to generate a baseline of the building behavior that normalized factors that are out of the control of the design, such as, weather or occupancy behavior, that cannot be statistically modeled to allow for fair comparision. From the technology development aspect at our firm Contecht we probably came furthest in setting up parametric modeling tools that allow for early simulations and host these tools through dedicated APIs that we developed in web-based design tools.