Underground cities have long been just sci-fi, but recently cities and urban architects have taken the idea of an underground city seriously. The biggest challenge is to show people that they can feel comfortable underground.
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Original text by: STEPHEN ARMSTRONG
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Originally published on Tuesday, November 12, 2019
Around 1800 BC, people in the Cappadocia region of present-day Turkey agreed that the environment was too inhospitable.
In addition to extreme weather, they also faced constant threats of war. Therefore, they decided to dig a city underground. Derinkuyu, the oldest underground city, still exists. They created a city for 20,000 people, which had schools, homes, shopping areas, and workplaces protected by large stone doors. These stone doors could seal each floor separately.
In 2010, Helsinki, Finland, attempted the same thing. The City Council approved the Underground Master Plan, completed in 2019. This plan covers the entire 214 square kilometers of the city. It combines energy storage, shelter from the long and harsh winter, and a prepared bunker in case of aggression from Russia.
However, it is not just a matter of security and protection from the weather that has led to living underground. Living below the surface offers an alternative to large high-rise building blocks for a growing population. Asmo Jaaksi, a partner at the architectural studio JKMM in Helsinki and the chief architect of the city's Amos Rex Museum (an underground museum), says that life underground retains heat and can be a safe place to take shelter in case of an escalating climate crisis.
Helsinki has long experimented with living underground
The Temppeliaukio Church, designed by architects Timo and Tuomo Suomalainen, was "sunk" in the Toolo district in 1969. In 1993, the Itakeskus swimming pool was designed for 1,000 visitors a day and a shelter for up to 3,800 people in an emergency.
"Helsinki stands on stable ground; they have a good foundation," says Jaaksi. "The city is overcrowded, and we have long and cold winters here. The underground offers us more space and protects us from bad weather," agrees Ilkka Vähäaho, director of the Helsinki Geotechnical Institute. Vähäaho also talks about other reasons to expand the city underground, including: "Finland needs open space even in the city center - building part of the city underground creates more space on the surface."
And that's why Helsinki's plan could bring a new approach to living underground. With an estimate that by 2050, up to 60% of the population will live in cities, housing for 2.5 billion people will need to be found. The city area is limiting, and space in the city is a limited resource. There is a practical limit to how high buildings can be, and spatial arrangements, protected buildings, or urban greenery in many cities like Paris, Mexico City, and Singapore are considering that the answers do not lie in more skyscrapers, but why not build underground?
In 2017, Paris announced a competition called Reinvent Paris 2.
This called on designers to utilize unused and underused spaces owned by the city. Most of them were underground. These included the cellars of historic buildings, tunnels where cars were banned along the Seine River, unused reservoirs, old parking lots, and asphalt surfaces. They transformed these spaces into restaurants, shops, and micro-farms for edible insects.
Architects in Mexico City have chosen a different approach
They designed a 300-meter-deep pyramid called Earthscraper. It was supposed to be built on the main square in Mexico City. However, the $800 million (€726 million) price tag thwarted the plans.
Meanwhile, the government in Singapore has invested
...more than $188 million (€170 million) in engineering and research for underground constructions. They have also amended the law so that all basements now automatically belong to the state. According to the Singapore Statistics Office, the population of 5.53 million people shares just under 719 square kilometers of land. This makes Singapore the third most densely populated place on Earth. So far, the city has been building upwards, with buildings in the city reaching up to 70 floors, pushing the island's coastline. With an estimated increase of 1.5 million people in the next 15 years, Singapore's options are limited by their area. The city is exploring the idea of an Underground Research Park 80 meters below the surface, which would house 4,500 scientists and researchers in an underground skyscraper with shopping centers, green infrastructure, highways, trains/subways, and ventilation canals. The design is cylindrical to withstand earthquakes. The cost of building it twice as high as skyscrapers has dampened hopes for realization.
"It is likely that global warming, as in Singapore with its complicated weather and fear of Chinese aggression, will lead cities to live underground. The result will be that cities will be built partly underground to limit extreme weather and partly above ground to ensure sufficient natural light supply.
In the past few years, it has become clear that the Singapore government has started to move strategic things underground.
For example, the Singapore Caverns under the city, which were used for ammunition storage, and the Jurong Rock Caverns under Singapore's Jurong Island are being used as the first underground oil storage facilities. Built by Hyundai Engineering and Construction, the underground storage facilities have five large caverns, 100 meters deep, and 8 kilometers of tunnels. In March, the government introduced the first stage of its own Underground Land Use Plan in three districts: Marina Bay, Jurong Innovation District, and Punggol Digital District. At the presentation to the media, Singapore's chief architect Hwang Yu-Ning said the plan would prepare space for the future, create capacities for growth, and protect the environment. She highlighted Singapore's first 230 kV underground substation in the basement of a commercial building and the centralized cooling of buildings on Marina Bay's coast to reduce energy consumption for cooling by 40%. Cooling with water has reduced CO2 production by 34,500 tons, equivalent to about 10,000 cars on the roads.
Storing energy underground
It is one of the biggest attractions for urban planners, according to Dale Russell (Professor of Innovation Design Engineering at the Royal College of Art). "Building underground saves space and definitely energy," explains Russell. "The topography itself can produce energy, rocks absorb heat in the summer, cooling the city. In winter, they release this energy like large radiators to heat the buildings. By 2069, we can expect fully self-sufficient transportation and ecological systems underground, as well as hydroponic cultivation with artificial light to supply the city with its own food."
For example, the subsoil under Paris has very high humidity and a constant temperature of around 14°C, regardless of the outside temperature. "If we build in a very hot place like Dubai or a very cold place like Scandinavia, the construction will cost less over a long period. The temperature is stable, so cooling and heating will be reduced," says Gunnar Jenssen, head of underground psychology at the Scandinavian research organization SINTEF.
The problem, says Asmo Jaaksi, chief architect of the Helsinki underground Amos Rex Museum, is not the building itself. "It's about making people feel good while staying underground," he explains. "The museum was running out of space and needed a new, larger building. The only option for the modern cinema called Rex was to excavate a square outside Rex and "sink" the museum lower. We found that people need contact with the surface."
Jaaksi's solution was to create artistic light shafts that allow natural light and curious views into the building. In London, the world's first underground farm was established in an original air raid shelter under Clapham Common. Growing Underground, they hydroponically grow lettuce, garlic, wasabi mustard, fennel, radishes, which they sell to M&S and Ocado. A pink light is used for growth, which becomes uncomfortable after a long stay.
The Lowline laboratory In New York
was working on an experimental project from October 2015 to March 2017, where they grew plants underground using solar panels and copper pipes to bring natural light into the tunnels below. They successfully grew over 100 different types of plants. The Lowline Lab is preparing the first green underground space in 2021.
Will we ever join the people of Cappadocia and move below the Earth's surface?
Jaaksi believes so. "Life underground will be part of the future of cities," he says. "Underground spaces are temperate with less variability in temperatures, retain heat, have better reservoirs for drinking water due to less contamination from surface water, and geothermal energy. As global warming creates a hostile environment on the surface, the underground may be the safest place. Do you really want to be in a skyscraper when a tornado comes?"