Stefano Boeri wants to bring living nature into the homes of city dwellers. “It’s different concept altogether,” the Italian architect says. “We have to imagine a kind of double simultaneous movement: one being the movement of citizens in the direction of the forest because it needs us to protect and maintain it, and the second, the movement of trees in the direction of the city.”

He elaborates: “If we want to tackle climate change, we now have many technologies like solar panels and geothermic tools to reduce the consumption of energy and use renewable energies. It’s important to invest in this kind of technology, but if we think of how we can absorb the CO2 that we have already produced, we have only trees, plants and forests. The basic reason for multiplying the number of trees inside our cities? They absorb CO2 and transform it into oxygen. I believe that’s an amazing, radical way to tackle climate change.”

Stefano with a tree growing in one of his vertical forests. 

As cities consume 75 per cent of the earth’s natural resources and account for more than 70 per cent of global CO2 emissions, which largely determine the global mean surface warming of the planet, growing more trees and plants can be part of the solution as they absorb nearly 40 per cent of fossil fuel emissions.

Stefano is constructing high-density towers for trees that are inhabited by humans and aimed at improving the quality of life by inviting nature into the heart of steel and concrete jungles. It’s not merely about a green wall or a roof garden, but also about growing plants and trees – oak, beech, larch, olive, cherry and apple – in planters on the overhanging balconies of high rises from top to bottom, resulting in a landmark that mutates with the seasons.

Palazzo Verde, Stefano’s first project in Belgium that’s currently under construction in Antwerp. 

He realised this in 2007 while on a trip to Dubai, an ultra-modern city in the middle of the desert, where he observed the madness of its hundreds of skyscrapers with reflective glass facades. This urged him to imagine an alternative. Of course, if he had his way, our planet would be populated by entirely self-sufficient cities composed of vegetal towers.

A good example is Stefano’s Smart Forest City in Cancun that is a 557ha urban forest for 130,000 inhabitants that not only places them back in nature but is intelligent at the same time. It’s a matter of the environmental survival of contemporary metropolises.

On 2014, he erected his first Bosco Verticale (Vertical Forest) of two residential skyscrapers, rising 112m and 80m respectively, in Milan. The prototype of sustainable buildings with facades carpeted with the leaves of 800 trees, 5,000 shrubs and 15,000 plants of 100 different species, it focuses on the relationship between humans and other living species.It also forms a microclimate that aids in the absorption of CO2 and fine particles from automobile traffic, produces oxygen, improves air quality, lowers temperatures, shields from noise pollution, minimises energy consumption and promotes biodiversity.

Approximately 1,600 specimens of birds and butterflies have made the trees and bushes their habitat, and ladybirds were released inside the greenery as a natural pesticide. Stefano consideres vegetation not just as ornaments, but as a basic building block of architecture.

Named one of the 50 Most Influential Tall Buildings of the Last 50 Years that represents a momentous change in thinking or technique by the Council of Tall Buildings and Urban Habitat (CTBUH) in 2019, the Bosco Verticale has not only become a highly-recognisable symbol of Milan, but also a shining example of metropolitan reforestation embracing the close cohabitation of architecture and nature and defying energy-consuming urban sprawl.

The Bosco Verticale has not only become a highly-recognisable symbol of Milan, but also a shining example of metropolitan reforestation embracing the close cohabitation of architecture and nature and defying energy-consuming urban sprawl.

Born in 1956 in Milan, Stefano graduated in 1980 in architecture from the Polytechnic University of Milan and received a doctorate in 1989 from the Istituto Universitario di Architettura di Venezia. After founding Boeri Studio in 1999 with Gianandrea Barreca and Giovanni La Varra, he established Stefano Boeri Architetti in 2008, with offices in Milan, Tirana (Albania) and Shanghai, where Yibo Xu is a partner and principal architect.

He was also the director of international architecture and design magazines, Domus and Abitare, Councillor for Culture in Milan from 2011 to 2013, and has been chairman of Fondazione La Triennale di Milano, a prominent Italian art, design and architectural institution, since 2018. 

One of the primary actors in the debate on climate change in international architecture, Stefano launched a manifesto in 2018 as a call to action to ensure our survival by insisting on the importance of urban forestry, thereby making our cities healthier and more attractive. His towers can enlarge green surfaces and are one of the most efficient ways to try to reverse climate change.

The Trudo Vertical Forest in Eindhoven, North Brabant, in the south Netherlands.

His vision of the future of urban living in light of an exploding population growth is one in which the city and the forest are radically connected so trees, shrubs and plants become an integral part of life everywhere we go.“I don’t think the vertical forest is the only way to tackle the idea of forestation,” Stefano notes.

“We also have to multiply the number of plants by creating orbital parks around our cities, green roofs and community gardens. And I think that the concept of demineralisation and forestation can be declined in many different ways. What makes a vertical forest so interesting is that we can concentrate such a great amount of plants in a minimal footprint, whose capacity to absorb CO2, produce oxygen and absorb particles of pollution is amazing.”

“when we create a 120m-tall vertical forest, we are producing the equivalent of 2ha or 3ha of a real forest – in terms of the number of plants – in a small surface area, which is at the same time a living ecosystem with an amazing biodiversity of species.”

stefano boeri

“Normally, when we create a 120m-tall vertical forest, we are producing the equivalent of 2ha or 3ha of a real forest – in terms of the number of plants – in a small surface area, which is at the same time a living ecosystem with an amazing biodiversity of species. That’s why we are investing so much in the multiplication of vertical forests all over the world. However, we don’t replicate the same building every time. Instead, we work according to the biodiversity of each place. Our activity as architects in designing the facade is connected to the character and evolution trajectory of every plant.”

Liuzhou Forest City. Housing 30,000 inhabitants, the 175ha city in southern China proposes offices, houses, hotels, hospitals and schools covered by 40,000 trees and 1 million plants of more than 100 different species. 

Now, Stefano is exporting his invention across the globe to cities such as Lausanne, Barcelona, Frankfurt, Utrecht, Chicago, Bogota, San Vicente, Astana, Mumbai, Jakarta, Huanggang, Beijing, Shanghai and Shijiazhuang. All are in various stages of development, from concept to construction.

On completion, the Nanjing Vertical Forest will be the first of its kind in Asia once it opens. It will comprise two towers containing offices, a museum, a green architecture school, a private club, a hotel, multibrand shops, a food market, restaurants, a conference hall and exhibition spaces housing 800 trees of 27 local species and 2,500 cascading plants and shrubs, which will absorb 18 tonnes of CO2 and produce 16.5 tonnes of oxygen annually.

A rendering of the facade of Nanjing Vertical Forest in spring. 

Stefano has refused to trademark the term “vertical forest” because he recognises the social value of this kind of building and hopes other architects will create edifices ingrained with the same philosophy and even improve on what he’s done. He cites  how 1,000 Trees in Shanghai by Heatherwick Studio or the works of MVRDV are possible ways of spreading his idea while keeping their identities.

Stefano. who teamed up with Diller Scofidio + Renfro to participate in a competition involving the retrofitting of a high-rise building, the design of a new skyscraper and the design of a new bridge connected to a park in Milan, visited Singapore about seven years ago and toured its architectural highlights.

An aerial view of Polcevera Park and the Red Circle, a winning proposal for a sustainable regeneration master plan in Genoa, Italy, that was co-created by Stefano Boeri Architetti, Metrogramma Milano and Inside Outside of Amsterdam. 

“Singapore is a very peculiar combination of a Chinese strategic approach to allotment and an openness to Western models,” he remarks. “What it has done in terms of making the city greener is very important and what’s happening in terms of mobility is quite interesting. Parts of Singapore are like a smart city that’s extremely advanced technologically. I consider it to be one of the most interesting parts of the world, so I follow what’s happening there.”

He adds: “For instance, what WOHA has done with Parkroyal on Pickering is extremely interesting. It’s not especially about trees but more about implementing green surfaces on the terraces of huge buildings. I like what it has done.”

““Singapore is a very peculiar combination of a Chinese strategic approach to allotment and an openness to Western models.”

stefano boeri

When asked about how he can apply his concepts to such a high-density urban nation as Singapore, he replies, “The space is limited. You have to experiment to find a new way of construction, a new way of using this limited space. The notion of density is a precondition. You cannot avoid it. This is something that is going to happen everywhere in the world because we cannot imagine developing new cities in the future simply by extending what’s already urban. We have to densify existing cities or build new ones that will become extremely dense, and in this notion of density, we have to integrate forests and trees.”

Amatrice Piazza del Gusto. Following the devastating Amatrice earthquake in 2016, Stefano created a symbol of a renaissance: a 2,500 sq m temporary multipurpose meeting place with a school canteen and eight restaurants, in which all the social and catering activities interrupted by the seism could find a dedicated new home. 

A utopia for some, an urbanism of the future for others, Stefano’s works represent the development of a new generation of urban architecture and cities able to combat the pressing issue of climate change in a revolutionary way while serving as models for the planet’s future.

He explains why the relationship between the city and nature is such an important component of his architecture: “I believe that we have to change in terms of how we deal with the concept of nature. We have entered into a new period of life in the future of a city where we cannot perimeter living nature inside a city simply by creating parks and gardens. Neither should we put it outside. We have to experiment with a totally different proximity within the two spheres in many different declinations so that we articulate this relation in different parts of our urban environment.” 

Images courtesy of Stefano Boeri Architetti