When designing a large building, the designs of architects, engineers, and technical systems are brought together into a single 3D model, and that’s often when problems surface that wouldn’t be visible in separate drawings. A pipe runs through a beam. A cable crosses a ventilation duct. A technical room turns out to be smaller than initially assumed.
When these conflicts are discovered during the design phase, they’re relatively straightforward to fix. If found only once construction is underway, they quickly turn into expensive fixes. But can urban space be run through in the same way that structural engineers test their solutions in a 3D model, before any building begins?
That’s the question Hundipea set out to answer years ago.
From opinion to knowledge-based planning
When we wrote about Hundipea’s digital twin on our blog in 2023, we described it mainly as a tool of the future. A vision for making urban planning more knowledge-based and interactive.
Architect Indrek Allmann, one of the authors of Hundipea’s future vision, put the problem plainly at the time. “Until now, urban planning has largely been based on opinion and experience,” he said. “People or decision-makers develop a sense over time; from experience comes opinion, sometimes prejudice, and from that, very large decisions have been made.”
In his view, great cities often emerge from good experience and skill. But that cuts both ways. “If those decision-makers have been mediocre in their experience, skill and biases, then a lot of what’s been built around us has genuinely been mediocre too.”
Hundipea’s goal was to reach a point where the impact of significant spatial decisions could be checked and evaluated before anything was built. That first required building a system that could bring together all information about the 42-hectare site in one place and allow it to be analysed from multiple angles.
Today, the information model underlying the digital twin is used daily for planning, research and assessing the impact of spatial decisions. To understand how it got there and what problem it solves, we need to go back to the very beginning.
Why was an information model needed?
Tarmo Miller, the Pluss Architects architect who led the technical development of Hundipea’s information model, describes the problem: “In a normal planning and design process, information that fundamentally comes from a single source tends to scatter across different media – drawings, views, tables and so on.”
At first glance, this doesn’t seem like a problem. It becomes one when the same information begins to live differently in different places. “These discrepancies arise because information in different media doesn’t communicate with each other. There’s no automatic checking or comparison; it’s mostly manual and incidental,” he explains.
For a small project, this may not be critical. At Hundipea’s scale, it means tens of hectares, thousands of future residents, and a development process spanning decades.
“You need to manage the spatial information of a vast area, steer it toward good urban quality, enable long-term sustainability analysis, and launch the subsequent design process as smoothly as possible,” says Miller.
That need gave rise to Hundipea’s information model. The goal, in Miller’s words, was to create a single source of data for the entire site, a model where every street, plot, building volume and spatial element represents, one to one, what it actually is. That model became the foundation for the digital twin.
The city as an information system
The greatest value of the digital twin lies not merely in 3D views or visualisation. It lies in the fact that different bodies of knowledge begin to speak to each other.
The “single source” that Miller described allows different kinds of knowledge to meet. Where research, planning documents, environmental data and design solutions normally exist in separate files, the information model makes it possible to look at them as a whole, while also allowing movement in the opposite direction, from the big picture down to a very specific question or data layer.
“When people only see individual drawings, it’s hard to grasp the whole,” says Hundipea’s CEO Markus Hääl. “But when the entire system becomes visible, an understanding of how different decisions connect emerges much faster.”
“The digital twin allows you to look at the site as a whole and understand how different layers of information relate to one another. At the same time, you can zoom in to a very fine level of detail and focus on a specific layer or question. This doesn’t only help specialists. It helps officials and current and potential partners reach a shared understanding of what we’re actually planning much more quickly,” he adds.
The digital twin as an urban laboratory
Markus has said before that all of Hundipea could be a kind of urban laboratory, a place to test new approaches to urban space. In its own way, the digital twin is the digital equivalent of that laboratory.
The twin is certainly not finished – it grows alongside the knowledge that accumulates over time. New analyses, simulations, measurements and knowledge layers are added continuously. The same spatial geometry also serves as input for assessing solar radiation, wind conditions, temperatures, energy use and various comfort indicators.
Back in 2023, Allmann already stressed that tools alone solve nothing.”As in information technology generally, you can have tools, you can have applications, but if you don’t know how to ask the right questions, you won’t learn anything.”
That’s precisely why collaboration with researchers and experts has been central to Hundipea’s development. One early lesson came from modelling the coastal climate within the digital twin. When observational data from the Harku weather station was added to the model, academician Tarmo Soomere pointed out that this data alone was insufficient. Hundipea sits by the sea, and under certain wind conditions, the area is affected by the upwelling of cold seawater, meaning actual conditions can differ considerably from what general weather data suggests at first glance.
Observations like this are what make it possible to reach better spatial decisions already during the planning stage.
The digital twin is not an end in itself
The twin itself has not undergone a major technological leap in recent years. Its greatest value lies in the fact that all information about the city is gathered in one place, and the impact of different decisions can be tested before anything is actually built.
Markus Hääl offers a very practical example: “Thanks to this, we can now analyse the impact of changes to revised detailed plans much more easily, without having to bring all the work in from scratch again.”
Urban space can and should be tested before it’s built
A good city is born from thousands of small decisions. How wide is the pavement. Where to plant trees. How much sunlight reaches a particular public square. How wind moves between streets. Which places become meeting spots.
The digital twin’s purpose is not to make those decisions on people’s behalf. Its role is to help us better understand their consequences. So the answer to the question posed at the start of this piece is yes. Urban space can be tested before it’s built, so that better decisions are made before they become real streets, squares and buildings.
