The development in Mexico is Stefano Boeri’s most ambitious forest city yet, covering a 557-hectare site. Largely food self-sufficient and powered by solar panels, it aims to be a "pioneer" for smart cities.
The climate crisis shows no signs of easing and cities are central to the solution. With over half of the world’s population now living in urban areas and this figure set to rise considerably in the coming decades, cities consume over two-thirds of the world’s energy and account for more than 70 per cent of global CO2 emissions.
Perturbed by that statistic, Stefano Boeri, the Italian architect of Milan’s Bosco Verticale, has unveiled plans to create a ‘Smart Forest City Cancun’ in Mexico. A combination of sustainable energy, smart city technology and millions of plants aims to allow the city to reach its target of carbon neutrality.
The project could serve as an important showcase of solutions and approaches other cities can adopt to combat climate change.
Boeri’s Bosco Verticale – the iconic, tree-covered residential building constructed five years ago – set the bar for integrating plants into a building’s design.
Boeri’s Bosco Verticale – the iconic, tree-covered residential building constructed five years ago – set the bar for integrating plants into a building’s design. Replicas have popped up all over the world since then, and Boeri has even designed entire ‘forest cities’ in polluted areas such as the Liuzhou Forest City in China (for 30,000 inhabitants).
Cancun is Boeri’s most ambitious forest city yet. Funded by property developer Grupo Karim, it covers a 557-hectare site and is targeting a population of 120,000. Largely food self-sufficient and powered by solar panels, it will, believes Boeri’s studio, be a "pioneer" in the sector.
Big data management will be used to improve governance and an on-site research centre could host organisations concerned with sustainability issues. Electric and semi-automatic transportation will allow inhabitants to leave their cars on the outskirts of town.
A 2019 ETH Zürich research project found that "[forest] restoration isn’t just one of our climate change solutions; it is overwhelmingly the top one". In Cancun, 7.5 million plants, including 260,000 trees planted throughout the city, are expected to absorb 5,800 tons of CO2 per year.
Briefed to create a "smart forest city" from scratch, the starting point was to question what the term means. Transsolar KlimaEngineering, the consultancy that aided Boeri’s studio on the project, concluded that the definition must include more than simply technology add-ons designed to optimise functionality.
Instead, for Transsolar, the “smart city” label became a call to find macro solutions geared towards achieving broad objectives – optimal energy-efficiency, self-sufficiency and liveability – principally through the city’s intelligent design.
"We found ourselves asking: ’Why would we try to build a city that is stupid?’," says Tommaso Bitossi of Transsolar. "I live in New York. Depending on which way the wind is blowing, I am sometimes unable to walk to work and have to change routes. We can’t have that in Cancun."
Buildings in Cancun are expected to consume half the energy of a standard Mexican building. Reaching that figure required outside-the-box thinking.
Buildings staggered at different heights will allow for greater air penetration, thereby enhancing natural ventilation, while half of office spaces will be open-air – a decision that takes advantage of Cancun’s warm, breezy climate.
Meanwhile, natural ventilation and newly developed mist fans will both provide low-energy-demand solutions. Americans tend to cool office spaces to 24-26°C, says Bitossi; thanks to Cancun’s particular cooling systems, which allow for greater air movement, between 28 and 30°C will be a reasonable target temperature.
Expected total energy consumption has been further reduced through adoption of a clever economic model – above a certain threshold it will be more expensive for inhabitants to consume electricity.
Buildings staggered at different heights will allow for greater air penetration, thereby enhancing natural ventilation, while half of office spaces will be open-air.
Moreover, the city’s integrated infrastructure means functionality can be multiplied. Canals used to irrigate farms, for example, will simultaneously supply the buildings’ energy-efficient heating and cooling systems, as well as feeding water gardens designed to reduce the threat of flooding. They will also play a part in the city’s transport system, providing navigable routes for boats and landing strips for sea-planes.
Smart Forest City Cancun’s circular economy will further contribute to its self-sufficiency. Water fed through the canals will be collected in a basin and desalinated in an on-site tower, and the fields they feed will be used to cultivate perishable food. Sargassum, a brown algae on Cancun’s beaches that is unattractive to tourists, will be used as a biofuel to provide a small proportion of the city’s overall energy supply.
Such integrated solutions were possible, says Bitossi, thanks to the diverse team Boeri has assembled, noting that good communication between professionals in different sectors will be key to making the next breakthroughs in smart city developments.
"When [the agronomist] Laura [Gatti] said we were going to have canals, I said: ‘Great! Can we also use them for the energy system?’," Bitossi says. "We now have so much information on how to make life greener. The next challenge is to better share knowledge. We won’t be able to unlock cities’ full potential unless we do that."
Vegetation itself has a real role to play in making cities liveable rather than simply environmentally friendly. Laura Gatti, the project’s agronomist and landscape designer, explains that trees will absorb stormwater, cool the surrounding air and provide shade thus improving walkability.
Having plants in urban areas, she adds, also brings less tangible benefits: "Green spaces are important for the soul," says Gatti. "Our brains prefer biodiversity. That is hardwired into us; urban living has not changed us that quickly."
Yet maximising satisfaction through a city’s design is a complex business, says Bitossi. After studying the results of surveys previously carried out by Transsolar, he has concluded the best way to do so is by providing choice.
"One day I may want to spend the day on the beach; another, I might want to walk in the shade. Therefore, we need to allow people to do both," he explains.
Further variables are expected to be beyond the designers’ control. "Buildings are living organisms rather than machines,” says Bitossi. "This is where the inhabitants come in. We will encourage them to monitor data displayed on monitors placed in residential buildings, allowing us to make tweaks to optimise energy flows, for example."
"One day I may want to spend the day on the beach; another, I might want to walk in the shade. Therefore, we need to allow people to do both."
For some long-term solutions, foresight, and patience will be required. While in Cancun energy will be stored in existing private and public networks, Mexico could go the same way as Germany, where storage systems are reaching full capacity.
As new storage systems are currently energy-inefficient and expensive to build, Bitossi advises waiting until emergent power-to-gas technology is advanced enough to be implemented on a large scale. In the meantime, administrators in Cancun should save money to switch systems when required, he suggests.
Only after determining the overall city design did Transsolar turn its attention to which additional technology to include. An app could help inhabitants make energy savings, for example, by suggesting to use the washing machine during the day, when solar energy is most readily available.
Also in the pipeline are self-driving cars, sensor-enabled parking spot tracking, smart street lights that turn on only when people are detected below and a robotic boat that will collect waste in the canal. The batteries of e-cars and e-bikes may eventually be a handy solution to foreseeable energy storage problems.
Which lessons from Cancun can help improve existent cities? Gatti points to ForestaMi, the ongoing project in Milan spearheaded by Boeri, as evidence of the general growing desire to ensure cities have a more positive impact on the environment. Cancun, she says, shows the multifarious benefits such forestation projects can bring.
For Bitossi, Cancun demonstrates architecture will be increasingly key to the future of cities.
Therefore, collaboration and the ability to comprehend complex challenges will be essential. “Cities cannot be smart without design,” he says. “The only way to make real progress is to use design to better harness what we find in our immediate environments.”
Details of the development timeline for the Smart Forest City Cancun project are expected to be finalised later this year.
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