Stefano Boeri builds tree houses, but they’re not the kind you might imagine. Instead, the Milanese architect and urban planner is constructing high-density towers for trees inhabited by humans aimed at improving quality of life by inviting nature into the heart of the steel-and-concrete jungle. It’s not simply about a green wall or roof garden, but growing plants and actual trees – oak, beech, larch, olive, cherry and apple – in planters on the staggered, overhanging balconies of skyscrapers from top to bottom, which results in a landmark that mutates with the seasons. If we were to compare his high rises to a tall tree, the balconies would be the branches, the plants the leaves, the central structure the trunk and the hydraulic watering scheme the roots, where irrigation is performed with groundwater pulled by a pump system powered by solar panels on the roof. And if the Italian architect had his way, our planet would be populated by entire sustainable forest cities composed of these vegetal towers. For him, it’s a matter of the environmental survival of contemporary metropolises. So in 2014, he erected his first Bosco Verticale (Vertical Forest) in Milan composed of two residential skyscrapers rising 112 and 80 meters respectively, the first prototype of a sustainable building featuring façades carpeted with the leaves of 800 trees (ranging from 3 to 9 meters tall), 5,000 shrubs and 15,000 plants of 100 different species, which focuses on the relationship between humans and other living species. Making up the equivalent of three hectares of woodland and undergrowth concentrated in just 3,000 sqm of urban space, it forms a micro-climate, absorbs CO2 and fine particles from automobile traffic, produces oxygen, improves air quality, lowers temperatures, shields from noise pollution, reduces 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. Boeri considered vegetation not just as ornamental, but a basic building block of architecture. Named in 2019 one of the 50 Most Influential Tall Buildings of the Last 50 Years that represent a momentous change in thinking or technique by the Council of Tall Buildings and Urban Habitat, it has become not only a highly-recognizable 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.
As cities consume 75 % of the earth’s natural resources and account for more than 70 % 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 % of fossil fuel emissions. Creating new green roofs, walls, façades and corridors, vegetable gardens, parks and other types of public greenery can help to prevent global temperatures from rising above 2°C. One of the primary actors in the debate on climate change in international architecture, Boeri 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 have the ability to enlarge green surfaces and are one of the most efficient ways to try to reverse climate change. His vision of the future of urban living in light of exploding population growth is one in which the city and the forest are radically connected to one another, where trees, shrubs and plants become an integral part of life everywhere we go. There are two main ways to develop this concept: one is to make existing cities greener and the second is to build new forest cities from the ground up. He came to the realization in 2007 during a trip to Dubai, an ultra-modern city in the middle of the desert, observing the madness of its hundreds of skyscrapers with reflective glass façades, and decided to imagine an alternative.
Born in 1956 in Milan, Boeri 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, then a Shanghai-based outpost together with Yibo Xu five years later. Director of international architecture and design magazines, Domus and Abitare, he was Councillor for Culture in Milan from 2011 to 2013, and has been the Chairman of Fondazione La Triennale di Milano, a major Italian art, design and architectural institution, since 2018. A reference in sustainable architecture and regeneration projects in complex environments around the world, where it’s not only about building green, but also about restoring ravaged physical, natural and cultural areas, Boeri helped in the reconstruction efforts following the devastating earthquakes in central Italy in 2016. Creating symbols of renaissance, he conceived the Amatrice Piazza del Gusto and Multipurpose and Civil Protection Center of Norcia in record time as places for the revival of the economic and recreational activities of the communities. Following the tragic collapse of the Morandi Bridge in Genoa in 2018 causing several deaths, he imagined The Polcevera Park and The Red Circle, a system of parks with different ecologies bringing together a variety of plants and trees typical of the Mediterranean basin, infrastructures for sustainable mobility and smart buildings for R&D and manufacturing that will run under the new bridge designed by Renzo Piano. Composed of a ring in the form of a walkway, raised square, access and exit ramp, corridor between buildings or underground path for pedestrians and cyclists that links separate sections, it is also equipped with a 120-meter-high wind tower for the production and distribution of renewable energy. More than rebuilding from an architectural and urban point of view, it’s above all about rejuvenation on a societal level with the aim of reversing the current image of the Polcevera valley and transforming the city into a territory of sustainable innovation.
Currently under construction is Nanjing Vertical Forest, which will be the first Vertical Forest in Asia once it opens: two towers containing offices, a museum, green architecture school, private club, hotel, multi-brand shops, food market, restaurants, conference hall and exhibition spaces housing 800 trees of 27 local species and 2,500 cascading plants and shrubs, which will absorb 18 tons of CO2 and produce 16.5 tons of oxygen annually. An upcoming Trudo Vertical Forest in Eindhoven marks the first time the Vertical Forest concept will be applied to social housing. The challenge is to design affordable structures for low-income residents, not just the wealthy. By decreasing construction costs and using prefabrication for the façade without reducing the number of trees or plants, Boeri hopes to demonstrate that it’s possible to unite two primary issues for the future of our cities: climate change and poverty. Now he’s exporting his invention across the globe to cities such as Lausanne, Paris, Barcelona, Frankfurt, Utrecht, Chicago, Sao Paulo, Bogota, San Vicente, Astana, Mumbai, New Delhi, Jakarta, Huanggang, Beijing, Shanghai, Shijiazhuang and Chongqing, all currently in various stages of development, from concept to construction. An experiment, he refused to trademark the Vertical Forest because he recognizes the social value of this kind of building and hopes other architects will create edifices ingrained with the same philosophy and improve on what he’s done.
The concept is pushed even further as Boeri is currently developing entire self-sufficient, environmentally-friendly Forest Cities, expanding his vision to a citywide scale. Smart Forest City in Cancun is a 557-hectare urban forest for 130,000 inhabitants that would place human beings back in the midst of nature and is intelligent at the same time. Hosting 400 hectares of green spaces including new public parks, private gardens, green roofs and green façades filled with 7,500,000 plants, it will absorb 116,000 tons of CO2 per year. The open and international city focused on technological innovation and environmental quality is conceived to be completely food and energy self-sufficient. Surrounded by solar panels and agricultural fields irrigated by a water channel connected via an underwater maritime pipe, it will be defined by a full circular economy with a transportation system that allows people to leave their vehicles at the edges of the city and rely solely on internal electric and semi-automatic mobility. Housing 30,000 inhabitants, the 175-hectare Liuzhou Forest City in southern China proposes offices, houses, hotels, hospitals and schools covered by a total of 40,000 trees and 1 million plants of more than 100 different species. Boeri is also developing the most far-reaching national and territorial urban reform in Albania of the last 25 years that aims to redefine the capital as a new metropolitan city. Known as Tirana 2030, the general local plan and master plan includes a continuous orbital forest system around the city, ecological corridors, a redesigned urban mobility system, a Vertical Forest, a building near the Presidency, a mixed-use building in the Blloku district and a school. The first Vertical Forest in Africa, planned for Cairo, will comprise three green cubes – one hotel and two apartment blocks – with the goal to make the capital the first North African metropolis to face the major challenge of climate change and ecological reconversion through a campaign to install thousands of green roofs, vegetal façades and a series of green corridors traversing Cairo that will be gathered by a giant orbital forest. A utopia for some, an urbanism of the future for others, one thing is certain, Boeri’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 future of the planet.