Will underground developments become part of the modern city?

The image of underground developments is changing as the world experiments with subterranean shopping streets, hotels, arts centers and even parks.

22 de marzo de 2017

From damp and dark to light and airy, the image of underground developments is changing as the world experiments with subterranean shopping streets, hotels, arts centers and even parks.

From Montreal to London to Hong Kong, developers are now digging downwards to create the venues and buildings of the future. But far from being gloomy caverns, today’s architects are surprising their local populations with the attractiveness of their designs. “People think that it’s cold and damp below ground,” says Helen Gough, JLL’s Lead Director PDS in the UK. “But if it’s well-developed and if you deal with the light, ventilation and humidity issues, it seems to provide some extraordinary architecture.”

Hong Kong recently announced plans to build 1.5 kilometers of underground shopping streets as it struggles with high land prices and a shortage of space above ground. Such ideas are not new: Canadians have long headed underground for shopping and dining in a network of tunnels underneath urban centers such as Toronto and Montreal.

Now, single buildings are also following suit: London recently granted permission for the construction of a hotelin a former subterranean garage in Bloomsbury. Part of the design challenge will be to make its windowless rooms appear bright and welcoming.

Indeed, many people might struggle with the idea of spending extended periods under street level but these new projects are increasingly winning the support of investors and planners looking to maximize space in crowded cities.

Subterranean benefits

Natural light and fresh air may be lacking underground but structures often come with a sustainable side. Ian Chalk Architects, designers of the forthcoming underground LDN Hotel in London, is incorporating a wide range of plants to help keep air clean along with a state-of-the-art ventilation system capable of producing cleaner air than that on the streets. In the Netherlands, an underground car park in Katwijk aan Zee, which was named Best Dutch Building of the Year 2016 also acts as a flood barrier.

Over in Montreal, the city’s underground network protects its users from the -9 degrees temperatures of deep winter and the humidity of summer, helping to reduce the amount of energy needed to heat or cool stores above ground. As Gough says: “Energy costs are a very positive element for underground developments. Geothermal factors mean that these developments are naturally cool in summer and warm in winter. And the energy costs can be 80 percent cheaper.”

For a growing number of cities, heading underground is seen as a way to help beat congestion above ground. One aim of the Hong Kong project, according to Secretary for Development, Paul Chan Mo-po, is to move away from overground spaces in order to “ease the road traffic and enhance pedestrian connectivity in congested urban areas”.

Over in Finland, Helsinki has drawn up a masterplan for underground development. “Space, especially in the city center, is quite limited – so naturally there is a lot of interest in going underground,” Raila Hoivanen, from Helsinki’s planning department tells Leaf Review. “We wanted to make sure that we are reserving space for long-term work such as rail, road and metro tunnels, while leaving space for other projects.” Meanwhile in Mexico City, ambitious plans have been published – but not yet followed up – for a 75-storey inverted pyramid structure in the city center. But the lack of laws on underground building is one reason why progress has not been made.

A development challenge

While the idea of underground structures are catching on, the reality requires substantial funds and significant planning, which will deter many developers. “The deeper you go, the more issues there are,” says Michael Esheyigba, Associate Director at JLL who is currently working on a new five star 350 bedroom hotel development with six basement levels 30 meters deep in central London, the deepest commercial basement in London. The basement levels consists of a swimming pool and spa, a cinema, meeting rooms, a ballroom and banqueting facilities and a restaurant.

And the further you go, the more costly it is. “In city centers, you have to take into account the surrounding properties and you also need a lot of surveys. It could take you a year to get the surveys done in London, for instance,” says Esheyigba. Surveys in a city would cover the geology, metro systems, sewers and other utilities. Discovering historic remains – as often happens in old Roman cities, for instance – also delays projects. The enthusiasm of local authorities is often a deal-maker.

Air quality is a fundamental point. “It depends on the use of the space,” says Esheyigba, explaining that requirements would be much more onerous for a hotel than for car parking. “For a hotel, you need a lot of ventilation and you have to pay particular attention to safety and fire issues. You have to consider how long it takes people to get out in a safe manner.”

Light is another key consideration; architects are working out ways of bringing natural rays below ground. Atria are not the only possibility. Plans for the Lowline underground park in New York envisage collecting light in high-tech panels and reflecting it down through a series of pipes – and to such a degree that the panels would get the light they need for photosynthesis to allow plants and trees to grow.

There is only one kind of development that Gough sees as being totally unsuitable for the underground – that of heavy industry. She says: “It seems to be possible to build anything – particularly hotels, retail, housing, parks and leisure. We could well see more of it in years to come.”

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