Building Green Cities

Green cities in a virtual world using digital twin technology

This article first appeared in COMPASS, the 3DEXPERIENCE Magazine written by author Jacqui Griffiths

Virtual twins enable cities to go beyond smart and become sustainable and resilient

Cities bring together a spectrum of individuals and organizations – from residents, workers and tourists to property developers, energy providers and government authorities. Collaborating online, via 3D virtual twins that accurately mirror the city, enables them to conceive the efficient and sustainable future of this complex system of systems.

Cities consume two thirds of the world’s energy, produce more than 70% of its carbon emissions and generate vast amounts of waste. That makes them a key focus of countries’ efforts to limit global warming by 2050. As urban populations continue to change, government and industry must work together to build, operate and maintain housing and infrastructure that can serve more people with lower environmental impacts and remain resilient to various risks such as infectious diseases and floods.

How to do it? Carlo Ratti, founder of Italian design and innovation practice Carlo Ratti Associati (CRA) and director of the Senseable City Lab at the Massachusetts Institute of Technology (MIT), advocates making better use of data-driven insights into cities and their operations.

“Social and environmental sustainability should be our top priority in cities,” Ratti said. “Digital technologies have the potential to help our cities become ‘alive,’ as built structures equipped with sensors and artificial intelligence [AI] can respond to human needs in real time. Sensor-laden devices also make it possible for buildings to integrate better with Nature.”

Cloud-based collaborative platform technology and 3D virtual twins are proving essential to enabling that integration between built and natural environments. A 3D virtual twin of the city is an intelligent digital model based on geometric, topographical, demographic, mobility and health data. It serves as the foundation for all stakeholders to understand, explore, simulate, and plan the city in a multi-discipline and collaborative way. By working together on a shared virtual twin of the city, stakeholders can co-create sustainable solutions that factor in the impacts of their choices at every stage from design, construction and operation through to demolition and recycling of materials.

Space, time and sustainability

Ratti points to the COVID-19 pandemic as one indicator of the potential for cities to achieve sustainability. For instance, traffic congestion is curbed and pollution is less concentrated when people work from home and travel to the office on different schedules, avoiding “rush hour.”

CRA focuses on bringing together multi-disciplinary expertise and technology – specifically virtual twins and AI – to design groundbreaking sustainable urban solutions. For example, in Finland, Helsinki’s Hot Heart project will create an archipelago of floating, forested islands whose large water basin will store renewable energy – converted into heat – for use during periods of high demand. Virtual twin technology is integral to the project’s predictive energy management system, which also allows the national electrical grid to use Helsinki’s Hot Heart as a load balancer. In addition, it integrates with existing district heating control systems to optimize carbon neutrality and load balancing.

Collaboration is essential to ensure that projects like this meet the needs of society and the environment.

Helsinki’s Hot Heart project will create an archipelago of floating, forested islands whose large water basin will store renewable energy – converted into heat – for use during periods of high demand.
Helsinki’s Hot Heart project will create an archipelago of floating, forested islands whose large water basin will store renewable energy – converted into heat – for use during periods of high demand. (Image © Carlo Ratti Associati)

“Collaboration among experts from different disciplines is our only hope to tackle complex global challenges such as climate change,” Ratti said. “For instance, to develop the optimal solution for Helsinki’s Hot Heart project, we solicited the expertise from mechanical and marine engineers, microclimate experts, lightweight-structure masters, visualization designers, heat pump component producers, energy and digital automation engineers and financial analysts.”

Working together in a virtual city

CRA isn’t the only organization using virtual twins to improve sustainability in cities. In the French city of Rennes, virtual twin technology provides a platform for unprecedented collaboration on city planning and management. “Virtual Rennes” is a real-time, computerized 3D twin of the city that integrates and cross-references a wide variety of data including topographical elements, demographic movements and health and energy information. A collaborative cloud-based solution is available to any authorized person for real-time collaboration to enable internal and external stakeholders to observe, discover, simulate and work together on ideas at every level of city life.

“We needed to address the complexity of the city and to be able to work with all the region’s stakeholders,” said Isabelle Pellerin, vice president, higher education, research and innovation at Rennes Métropole, the public institution responsible for the city. “The 3D model has become a digital twin of the metropolis – a database connected to other city ​​and territory systems, mobilizing cooperation of all public and private actors, and in particular citizens.”

Virtual Rennes is used in many projects, including how proposed new construction will affect the sunshine that reaches existing buildings, projecting future tree growth to assess landscaping, and modeling neighborhood noise.

“Today the model has become a platform which helps to build, monitor and evaluate public policies by crossing different types of data,” said Cécile Tamoudi, head of SIG at Rennes Métropole. “How do the measurements of the territorial climate-air-energy plan influence air quality? What is the surface area of ​​waterproofed floors? What is the impact on biodiversity of such developments?”

Toward a zero-energy Singapore

Collaboration also is at the heart of progress toward a zero-energy built environment on the island of Singapore. Here, a virtual 3D city model provides a common platform where government departments and researchers can work together on city planning, develop applications and simulations for test-bedding concepts incorporating environmental data to support sustainable choices. Reduced energy consumption, as well as energy efficiency, are essential to Singapore’s long-term vision. To help developers make the right choices, Singapore’s Building and Construction Authority (BCA) provides guidance alongside a comprehensive framework – the Green Mark certification scheme – to assess the environmental performance of buildings. The Super Low Energy (SLE) building certification is awarded to those that perform best – a vital stepping-stone on the zero-energy journey.

“With SLE, we are shifting the conversation toward energy consumption because cutting absolute consumption reduces the carbon we are emitting today,” said Benjamin Towell, an architect, surveyor and environmentalist who is deputy director of the BCA’s SLE Buildings department. “That can help to slow down climate change while we work on other technologies, and approaches to reduce the carbon across the economy and that’s already in the atmosphere.”

To make sure the policies and regulations are constructive instead of constrictive, BCA assessors consult with project stakeholders, providing case examples and suggestions to help constructors achieve the required standards and reviewing energy models to demonstrate to developers how using less energy will generate cost savings. Actions like these embody the shift in mindset that Towell believes is essential to achieve sustainability.

“There are many strong policies globally that are setting the right tone, but now the focus needs to shift toward actions and outcomes,” Towell said. “Outcome and performance are the critical points, and stakeholders might take different routes to reach them. By working with multiple stakeholders, we break down the silos that traditionally exist in construction project teams, and the Green Mark rating provides a common language to support that.”

The combination of technology with an outcomes focus helps to create that language.

“Digital technology can bring great advantages when the people delivering on the outcome can work in partnership with it,” Towell said. “Modeling their ideas in the virtual world enables them to crunch data, quantify their thoughts and test their designs much faster than in the real world. For instance, one small architectural firm used building information modeling to create such a finely detailed 3D model of the entire building that you could cut a cross-section and see where the fire exits, fire bells and visual alarms would be – details that many companies simply cut and paste onto their drawing as 2D symbols. Doing that created something that the contractor, client and assessor could fully understand and work with.”

Bringing worlds together

Ultimately, sustainable and resilient cities embody a partnership between the built environment and the Natural world – a convergence that can only be achieved with a full, multifaceted picture of what’s involved and how proposed changes could affect quality of life. In cities around the world, virtual twin technology delivered on a cloud-based collaborative platform is enabling the insights, shared understanding and system-level analysis required to achieve a full, rich picture.

“Users need to be able to shape technology tools to suit their processes, or shape their processes in partnership with the tools to deliver better outcomes,” Towell said. “This comes down to knowledge and capability, not the size of the organization. Those that can harness technology in this way are going to be better placed to do well in the future economy.”

Urban sustainability and resilience are less about the technology-focused ‘smart city’ concept, Ratti said, and more about a wider, environmentally and socially sensitive city where technology enables intelligent, inclusive operations.

“We want to focus on the human side of the city,” Ratti said. “Technology should not create new needs; it should help us to achieve the things we want to do today. This is what modern technologies are allowing us to do in our cities. By leveraging citizen participation and digital technologies, especially virtual twins, we can make our cities more livable – and loveable.”

Top image: Virtual twin technology is integral to Helsinki’s Hot Heart project’s predictive energy management system. It also integrates with existing district heating control systems to optimize carbon neutrality and balancing of electrical loads. (Image © Carlo Ratti Associati)

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