Back in 1800 BC, the people of the Cappadocia region of modern-day Turkey decided their environment was so hostile – with extreme weather and the constant threat of war – that they dug an entire city underground. Derinkuyu, the oldest underground city still in existence, housed 20,000 people, providing schools, houses, shopping areas and places of worship protected by large stone doors which allowed each floor to be closed off separately.
In 2010, Helsinki, Finland, essentially took the same approach. The city council approved an Underground Master Plan, completed in 2019, that covers the city’s entire 214 square kilometres – combining energy conservation, shelter from the long, cold winter and an enormous prepper bunker in case of Russian aggression.
But it isn't just security and seasonal weather touted as reasons for living underground. Subterranean living offers an alternative to huge tower blocks and growing populations. Asmo Jaaksi, a partner at Helsinki architectural practice JKMM and the chief architect of the city’s underground Amos Rex Museum, says living underground conserves heat and may, for some, be one of the safest places as the climate emergency escalates.
Helsinki has long pioneered underground living – the Temppeliaukio Church, designed by architects Timo and Tuomo Suomalainen was sunk into the city’s Toolo district in 1969 and, in 1993, the Itakeskus Swimming Hall – a large recreation centre that can handle 1,000 customers on an average day and converts into an emergency shelter with space for 3,800 people.
“Helsinki stands on bedrock – a good foundations and very stable ground,” Jaaksi says. “The city is very overcrowded, and we have such long, dark and cold winters. Underground offers more room and connects us together away from the bad weather.” Ilkka Vähäaho, the head of Helsinki’s geotechnical division, agrees. Vähäaho says other main drivers for developing underground include: “the Finnish need to have open spaces even in the city centre – taking parts of the city underground would allow more open space on the surface.”
This is where Helsinki’s plan could be pioneering a new attitude to subterranean living. With 60 per cent of the world’s population expected to be living in cities by 2050, meaning housing needs to be found for some 2.5 billion people, urban land is an increasingly limited resource. There is a practical limit to how high buildings can be built and due to space constraints, protected buildings or districts and green belts, many cities, such as Paris, Mexico City and Singapore are considering the answer lies not in more skyscrapers – instead, why not build down?
In 2017, Paris launched a competition, called Reinvent Paris 2, which asked designers to come up with uses for currently unused or under-used city-owned plots – most of which are underground. These include basements of historic buildings, tunnels freed up after cars were banned from the lower roads beside the Seine, unused reservoirs, old parking lots and former abattoirs. They have been turned into restaurants, shops, and a micro farm for edible insects.
Architects in Mexico City have taken another approach: proposing a 300m underground pyramid, dubbed the Earthscraper, that is planned to sit as a mini-city beneath Mexico City’s main square. However, a $800 million (£620m) price tag saw the plans shelved.
In Singapore, meanwhile, the government has already invested more than $188m (£146m) in engineering and research into underground construction and has modified its property rights laws so that all basements now belong automatically to the state. According to Singapore’s Department of Statistics, a population of 5.53m people share the island’s mere 719 square kilometres of land. This makes it the third most densely populated place on Earth. To date, the city-state has built upward – with apartment buildings reaching as high as 70 stories – whilst reclaiming land to push out the island’s coastline. But with projections for 1.5m more people in the next 15 years, Singapore’s options are as limited as its space.
The city is exploring the idea of an Underground Science Park 80 metres below the surface, which will house 4.500 scientists and researchers in an earthscraper with underground developments for retail parks, green city infrastructures, highways, train lines and channels for air-conditioning pipe work. The design is cylindrical to withstand earthquakes.
Costs for the Park – estimated at twice the price of an equivalent surface build – has cooled Singapore’s ardour for that project. “It’s like making a model of a building – is it easier and cheaper to use paste wood sheets or to carve inside a tree stump?” argues Marcos Martínez Euklidiadas at the Carlos III University of Madrid’s engineering department. “When you build underground you need to do everything you already do above ground then add the cost and effort of digging.
"It’s likely that the driver of this will be resilient cities especially as global warming disrupts weather – like Singapore with its complicated weather patterns and fear of Chinese aggression. The end result is likely to be built partially underground in order to avoid extreme conditions but with enough access to natural light.”
Even so, the last few years has seen the Singapore government start moving strategic essentials underground – including a deep cavern beneath the city used to store ammunition and the Jurong Rock Caverns beneath Singapore’s Jurong Island, the region’s first subterranean oil storage facility. Built by Hyundai Engineering and Construction, the underground structure has five huge caverns 100 metres deep and eight kilometres of tunnels to hoard hydrocarbons. In March, the government revealed it’s the first stages in its own Underground Master Plan in three districts – Marina Bay, Jurong Innovation District and Punggol Digital District.
Speaking to the media at launch, Singapore’s chief planner Hwang Yu-Ning said that the plans will create spaces for the future, build capacity for growth and conserve the environment. She pointed to Singapore's first 230kV underground substation in the basement of a commercial building and credited the new centralised cooling system – that pumps chilled water through pipes to cool waterfront buildings around the Marina Bay for reducing energy consumption by around 40 per cent, helping the buildings slash their annual carbon dioxide emissions by 34,500 tons – equivalent to taking 10,000 cars off the road.
Energy conservation is one of underground’s big attractions for urban planners, according to Dale Russell, a professor in Innovation Design Engineering at the Royal College of Art. “Building underground saves space and, ultimately, power,” Russell explains. “The topography itself can generate energy, the rocks absorbing the sun’s heat in summer to keep the city cool, releasing it in winter like giant radiators to warm the earthscrapers. Within such cities, by 2069 we can imagine a complete self-contained travel and eco system underground, using hydroponic farming systems with artificial light to grow the city’s own food supply.”
The ground underneath Paris, for instance, has a high humidity and a constant temperature of 14C, whatever the outside weather. “If you build underground in very hot places like Dubai or very cold places like the Nordics your project will cost less in the long term – the temperature is stable so the cost of ventilation or heating is reduced,” says Gunnar Jenssen, head of underground psychology at Scandinavian research organisation SINTEF.
The problem, says Asmo Jaaksi, chief architect of Helsinki’s underground Amos Rex Museum, is not the construction itself – “it’s making people comfortable to go underground that we found complicated,” he explains. “The museum was running out of space and needed a new, larger building. The only option, a modernist cinema called the Rex, would not have been big enough so we dug out the square outside the Rex and sunk the museum beneath. We found people needed to feel connected to the surface somehow.”
Jaaksi’s solution was elaborate, artistic skylights that let natural light and curious gazes in. This isn’t always possible. In London, a former air raid shelter beneath Clapham Common has become the world’s first underground farm – Growing Underground – hydroponically growing salad rocket, garlic chives, wasabi mustard, fennel, pink stem radish and purple radish which it sells to M&S and Ocado. The growing light used, however, has a deep pink tinge which becomes uncomfortable after long exposure.
In New York, meanwhile, the Lowline Lab ran an experimental two year project from October 2015 to March 2017 growing plants underground using solar panels on city rooves to deliver natural light to the tunnels below. Having successfully grown over 100 different species of plant, the Lab aiming for its first underground green space in 2021.
Will we ever join the people of Cappadocia and move beneath the surface? Jaaksi thinks – yes. “I think underground living will become part of the future of cities,” he argues. “Underground is temperate with less variability in temperature, conserves heat, has better drinking water thanks to fewer contaminants from surface wastewater and – well, geothermal energy. As global warming creates an increasingly hostile surface environment, underground might be the safest place. You really want to be in a skyscraper when the tornadoes start?”
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This article was originally published by WIRED UK
