Problem:

The parks and gardens of traditional cities spreading out horizontally or on slopes take up valuable building space, while potted plants and bonsai on balconies can only capture miniscule amounts of CO₂.

Solution:

Perhaps the earliest example of a “vertical farm” is the legendary Hanging Gardens of Babylon, built by King Nebuchadnezzar II more than 2,500 years ago. According to some scholars, the gardens consisted of a series of vaulted terraces, stacked one on top of the other, and planted with many different types of trees and flowers.

Reaching a height of 65 ft. (20 m.), the gardens were irrigated by an early engineering innovation known as a chain pump, which would have used a system of buckets and pulleys to bring water from the Euphrates River at the foot of the gardens to a pool at the top.

In the 1970s, Ken Yeang, a Malaysian architect, began to propose that instead of hermetically sealed mass-produced agriculture, plant life should be cultivated within open air, mixed-use skyscrapers or “Farmscrapers” for climate control and consumption.

In 2006, Stefano Boeri, Gianandrea Barreca and Giovanni La Varra, a team of architects in Milan, Italy, working with horticulturalists and botanists, designed two residential towers near the Porta Nuova Garibaldi railway station of that city, What made them different was that these towers, 364 ft (111 m.) and 249 ft (76 m.) in height, would contain more than 900 trees (approximately 550 and 350 in the first and second towers, respectively) on 96,000 ft.² (8,900 m²) of terraces.

In short, they were a Vertical Forest ( = Bosco Verticale), incorporating 900 trees, 20,000 shrubs and plants, which help mitigate smog by converting approximately 44,000 lb (20,000 kg) of carbon each year. Construction of the towers began in late 2009 and early 2010, involving 6,000 onsite construction workers. Between mid-2010 and early 2011 construction progressed very slowly and the towers rose and by the beginning of 2012 the structures were completed, and construction of the facades and installation of the plants began on June 13, 2012. The building was inaugurated in October 2014.

Before long, residents found that their Vertical Forest was attracting new bird and insect species to the city such as bumblebees, hermit wild bees, syrphidae (hoverflies) and more. It was also moderating temperatures in the building in the winter and summer, by shading the interiors from the sun and blocking harsh winds. The vegetation also protects the interior spaces from noise pollution and dust from street-level traffic.

The building itself is self-sufficient by using renewable energy from solar panels and filtered waste water to sustain the buildings’ plant life. These green technology systems reduce the overall waste and carbon footprint of the towers. After five years, these residential high-rises seem to be almost disappearing under all that green, and continue to be a testament to sustainable urban living.

The Milano model is being developed across the world. In Paris, Stefano Boeri Architetti are designing a 177 ft (54 m.) tower, Forêt Blanche, which will incorporate 2.5 ac (1 ha) of woodland. Another one is planned for Tirana in Albania.

The Vertical Forest concept is under development in future cities in China, including Shijiazhuang, Liuzhou, Guizhou, Shanghai and Chongqing The Nanjing Forest City project, scheduled to be finished in 2020, comprises a 340 ac(138 ha.) city featuring 40,000 trees and a million plants, a total of 1100 trees from 23 local species, as well as 2500 cascading plans and shrubs that will cover a 6,000 m² area.

As with the Bosco Verticale, the Chinese towers will help to regenerate local biodiversity and will provide 28 tons (25 tonnes) of CO₂ absorption each year. B+H Architects in collaboration with ECAD have developed an “urban living room” and rooftop gardens to animate the Shenzhen Children’s Hospital and Science and Education Building at the edge of Lianhuashan Park .Composed of gardens and play areas, this is to help children engage with nature and establish a playful, unintimidating medical environment.

In his book “A Forest City” Boeri has unveiled designs for three buildings covered with pollution-absorbing trees and plants in Egypt’s new administrative capital, which is under construction in the desert east of Cairo. The Egyptian project will be the first of its kind for Africa.

In October 2019, Stefano Boeri, commissioned by developer and textile giant Grupo Karim, presented plans for a new “smart forest city” proposed across 1376 ac (557 ha) near Cancun, Mexico which would be home to 130,000 people.

Touted as “the first forest city of the new millennium”, the new plans for Mexico include 988 ac (400 ha) of green spaces with 7.5 million plants, and 400 different species, 260,000 of which will be trees equating to 2.3 trees per inhabitant, The smart forest city will absorb 116.000 tons (105,000 tonnes) of CO₂ with 5.800 tons 5260 tonnes) of CO₂ stocked per year.

Water is a key element in the project: surrounded by a ring of solar panels and agricultural fields irrigated by a water channel which is connected with an underwater maritime pipe. Climate-responsive engineering firm Transsolar‘s involvement in the city plans for it to be completely food and energy self-sufficient.

Other architects developing plantscrapers, include Vincent Callebaut of Belgium, Rogers Stirk Harbour & Partners of London (Skyfarm), Plantagon of Sweden (World Food Building) etc.

In, India, taking a more modest approach, an Internal Revenues Services officer, Rohit Mehra with his wife Geetanjali and friends have been creating “green walls” in Ludhiana, a large industrial city in the north Indian state of Punjab, to minimise the effect of environmental pollution.

Very simply they take empty 3 and 6 pint (1.5 and 2-liter) used plastic bottles then fix rows of them vertically as flower pots, using drip feed irrigation. Having decorated the 2,500 ft² provided by the walls of their home, Rohit then applied it to the walls of his own office at Rishi Nagar, where over 18,000 bottles were used.

The next location, unveiled on Income Tax Day 2017 was Ludhiana’s railway station with a vertical garden displaying some 37,000 plants. Thanks to Rohit’s initiative, involving building one vertical garden in three or four days on an average, there are now 75 vertical gardens in Punjab, include premium hotels, district courts, schools and colleges like Punjab Agricultural University and even religious institutions like Gurdwara Dukh Niwaran Sahib in Ludhiana. While this totals 1.85 lakh (185,000) saplings, Team Green’s target is 1,000 vertical gardens across India to help curb pollution.

Discover Solution 325: Water battery

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