As drivers of development, cities are natural ground for innovation and are thus perfect sandboxes to see how simulations can help us with various challenges related to reaching multiple Sustainable Development Goals: building sustainable cities and communities (SDG 11), fostering industry innovation and infrastructure (SDG 9), taking climate action (SDG 13), as well as establishing partnerships to achieve the goals (SDG 17).

For example, Singapore’s use of its digital twin is already highlighted as best practice in the 2021 UNDP Handbook on Smart Urban Innovations. Its 3D virtual model allows new developments to be simulated with great precision. This digital twin is used in planning bicycle lanes and parking lots, taking into account many factors such as road obstacles, tree shading, surrounding facilities, traffic connections and other safety parameters. The model is also very useful for long term planning. Singapore’s ageing population will require major changes to infrastructure, and different actors can now work together virtually to make and test solutions.

The capital of Estonia, Tallinn, aims to use digital twins to increase public participation in urban planning and to track energy consumption. Seoul in South Korea uses it to predict wind paths and inform urban design in a way that reduces spread of forest fires, heat island effect (spots in urban areas with higher temperatures) and spread of fine dust.

Simulations need to be human-centric

What will come next? Simulation of entire societies and testing economic policies in virtual worlds before applying them in the real world? However, creating more complex and ambitious digital replicas raises questions about privacy and cybersecurity.

Many of these digital twins are made possible by a multitude of sensors that track real-world data and movement. Take for example workers at factories with digital twins that may find their every movement followed while a hacker of a digital twin could gain frighteningly precise knowledge about how a system works and what its vulnerabilities are. These risks can be compounded if they are related to citizens who are not aware of what data is collected about them, or management of key infrastructure systems such as, energy, heating or water supply .

Digital twins, like the metaverse, also have environmental impact as high-end data storage and processing are energy-hungry processes.

Furthermore, these technologies can be challenging to implement. Even the most basic ones require many elements to be put in place: data-collection capability of urban Internet of Things - sensing networks as well as protocols around data governance, system interoperability, fast data processing, ensuring data quality, security and privacy.

All of these challenges require both top-down (e.g. setting up centres to coordinate and manage all data) and bottom-up approaches (e.g. what do the citizens and other key stakeholders think are most important things to model), and all application scenarios need to be human-centric.

Finally, the initial development of digital twins can be costly and complex. Much of the initial investment tends to fall on the public sector, while private companies stand aside for the first few years until they can formulate a clear investment rationale. Even though public bodies may be the ones initially investing, they should engage all stakeholders, especially the private sector, to ensure standardisation and interoperability with future actual and potential users. 

Tool for a sustainable future

Nevertheless, digital twins, especially in urban settings offer significant benefits and opportunities for innovation. Remembering, once again, my first brush with urban simulation, playing SimCity, I realised that I enjoyed two things: no one wins or loses, and everything has a solution.

I am aware that digital twins of real cities will never be able to capture reality perfectly, and that there will always be mistakes, like those you see when running a city simulation on a basic PC. Real life, as we know, has high variability, is full of uncertainties and fuzziness and thus cannot be perfectly simulated nor can models serve as perfect guides to tricky questions of policies.

However, I believe that, through the use of precise mapping, integration and constant interplay between virtual and physical cities , monitoring, as well as their power for making predictions for various scenarios, digital twin cities can provide us with innovative solutions for a sustainable future. I also believe that, like in a game, there will be no losers in the city of tomorrow, and that our urban environment will become sustainable, more convenient and more inclusive.