Vertical Forests and Sustainable Cities

Stefano Boeri is an Italian architect and urban planner based in Milan and has become a ‘starchitect’ well known for the design of his ‘bosco verticale’ towers in the same city. You can barely see the tower itself, as it’s laden with dense forest, if this forest existed on flat land it would sprawl across almost 4 acres. The living forest is thriving whilst resting on concrete slabs at no less than 280mm thick, in one of Milan’s most dense urban areas, Porta Nuova. Bosco Verticale was a world first in urban forestry.

Bosco Verticale soaks up thousands of tonnes of carbon emission with its two residential towers at both 80m and 112m, hosting 780 trees, 11,000 perennials and 5,000 shrubs. With its initial estimate of 1,500 specimens of birds and butterflies it has already made a huge impact on the city’s flora and fauna volumes. It’s a towering example of biodiversity boasting hundreds of microclimates and gorgeous vistas enjoyed by everyone of the 400 residents means that it looks as beautiful inside as it does outside.

Aside from the vegetation insulating the building, it also uses heat-pump technology which slashes heating and cooling costs.

It absorbs small particle pollution from surrounding Milan, produces oxygen and is irrigated with the buildings grey water, which means water from the shower, sink, dishwasher and washing machine irrigate these suspended sky gardens as opposed to this water being delivered into Milan’s surrounding river-ways and in most cities, oceans.

Each tree stores 21kgs of CO2/year and produces 118kgs of Oxygen in the same time. So, for all the trees on the buildings that’s 16,380kgs of CO2 per year it absorbs and 92,040kgs of oxygen per year it releases. One tree takes up one tonne of carbon emission in its life time. The forest is also a natural noise barrier and improves the biodiversity of living species, generating the habitat for birds, insects and small animals.

Boeri and his team worked with botanists, engineers, horticulturists and environmental consultants to ensure that it uses the most sustainable of construction processes to deliver one of the greenest buildings on the planet. It is no surprise that Boeri’s creation has picked up multiple awards around the globe and inspired millions of budding young designers in the architectural community.

Boeri said, “one of our greatest challenges was the wind.” The design was tested in a wind tunnel to make sure trees were not blown off the building by huge gusts of wind these innovative urban, green colonies combine the challenge for energy self-sufficiency, the use of renewable energy with the task of trying to increase biodiversity and to effectively reduce air pollution in urban areas (which is critical for all cities) thanks to the proliferation of vegetation and biological surfaces within Boeri’s architecture.

Boeri is replicating his vertical forest template in many other parts of the world and in China in particular where it is super critical. The Master Plan for Liuzhou Forest City project; a new green city that fights air pollution planned to begin works by 2020.

Once completed, the new city will host 30,000 people, absorb almost 10,000 tons of CO2 and 57 tons of pollutants per year and produce approximately 900 tons of oxygen.

Liuzhou Forest City will be built in the north of Liuzhou, in the mountain area of Guangxi, in the southern part of China; in an area that covers 175 hectares along the Liujiang river.
The new green city, entirely wired, will be connected to Liuzhou through a fast rail line used by electric cars and will host various residential areas, commercial and recreational spaces, two schools and a hospital.

Liuzhou Forest City will have all the characteristics of an energy self-sufficient urban establishment: geothermal energy for interior air conditioning and solar panels over the roofs for collecting renewable energy.

Liuzhou Forest City will host in total 40,000 trees and almost 1 million plants of over 100 species. The diffusion of plants, not only in the parks and gardens or along the streets, but also over building facades, will allow the energy self-sufficient city to contribute to improve the air quality (absorbing both CO2 and fine dust of 57 tons per year), to decrease the average air temperature, to create noise barriers and to improve the biodiversity of living species, generating the habitat for birds, insects and small animals that inhabit the Liuzhou territory.

For the first time in China and in the world, an innovative urban settlement will combine the challenge for energy self-sufficiency and for the use of renewable energy with the challenge to increase biodiversity.

Last year Boeri launched his URBAN FORESTRY MANIFESTO – A Call To Action, globally.

Here it is in its entirety:

‘We, designers of the first Vertical Forest in Milan, invite architects, urban planners, botanists, agronomists, forestry corps, tree growers, geographers, ethologists, landscape scientists, technicians, researchers and experts in green care and urban forestry, real estate developers, administrators and representatives of local institutions and civil society, members and representatives of international organisations, funding agencies, universities and research institutes, and NGOs, to consider that:

– by 2030, 60% of the global population is projected to live in urban areas.
– cities consume 75% of the world’s natural resources and account for more than 70% of global CO2 emissions.
– cumulative emissions of CO2, together with methane and other greenhouse gases, largely determine global mean surface warming of the planet, causing ice melting, biodiversity loss and rising sea levels.
and to consider also that:
– forests and trees – which are at risk of continuous erosion all over the world – absorb nearly 40% of fossil fuel emissions largely produced by our cities every year.
– leaves and roots of a mature tree absorb CO2 through photosynthesis and help reduce the pollutants (responsible for a high percentage of respiratory diseases and premature deaths) present in the air.
– if a single tree can bring great benefits to the city and its inhabitants, an urban forest can be an extraordinary help to improve the quality of health and life in a city.

We believe that:
– cities, which are largely responsible for climate change problems, have the opportunity to become an integral part of their own solution , by increasing the number of forests and trees that can “fight the enemy” on its own ground (the city), using CO2 as fertiliser.
– increasing forests and trees in world’s cities can help absorb CO2, drastically reduce pollution, energy consumption and the “urban heat island” effect, increasing biodiversity of living species and making cities safer, more pleasant, healthier and attractive.
– a global action on urban forestry will help to prevent global temperature from rising above 2° C, the maximum acceptable threshold defined by the COP 21 agreement in Paris (2015).

we have the duty to launch a global campaign on urban forestry in order to multiply the presence of forests and trees in our cities.
Such a campaign should start with these major actions:
– protect and increase permeable and green surfaces in the city,
– create new parks and gardens,
– transform city roofs into lawns and vegetable gardens,
– transform perimeter walls and urban barriers into green façades,
– transform urban voids and courtyards into green oasis,
– promote community gardens and implement urban agriculture,
– use tree roots to decontaminate polluted soils,
– create a network of green corridors (tree-lined avenues, street trees…) to connect parks, forests, and green buildings,
– multiply the number of green buildings and vertical forests,
– create new orbital forests and woodlands all around our cities.

– if we want to reverse climate change,
– if we want to favour the survival of living species,
– if we want our cities to be greener, healthier and more pleasant places,
urban forestry should be a priority in the international agenda of governments and local and international institutions.

Join us. It’s time to act.
Share this call.’
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