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Super tall, super smart | Living the high life

arcology tower2

“This was an environment built, not for man, but for man’s absence,” novelist JG Balllard wrote of high-rises in 1975. So what is being done to make skyscrapers more habitable?

Whether you rent social housing or work in an office downtown, a lot of city dwellers have no choice about whether or not to inhabit tall buildings.

But in 2016, people are increasingly making the decision to live at height. Among buildings taller than 200m, those classified as residential rose from 34% in 2009 to 45% in 2010; during the same time, those classified as “offices” dropped from 42% to 20%.  Meanwhile, the United Nations Population Division projects that by 2050, 66% of the world’s population will be urban, up from 54% today.

So more people will be living or in skyscrapers. But is there a desire to live at height? Or is it a case of expediency?

Dire design

“95% of tall buildings are pretty dire pieces of design, actually,” says Council of Tall Buildings and Urban Habitat executive director Antony Wood.

As a professor of architecture, Wood has the right to be critical. But, he says, as a citizen, he is still in awe of man’s achievement to build ever taller – financially, logistically and technically.

But would he choose to live in one, to raise a family in one? Probably not.

“We need to rethink the skyscraper, rethink tall buildings and bring them back to being relevant to the place where they are, and maximise those factors… cultural, climatic, social, physical – the things that are often left out of the design process.

“Communal space inside these buildings is important if communities are to flourish like they could at ground floor – gardens, paths, roads – these need to be replicated in the sky, and in some places they are.”

One prime example of a skyscraper promoting public space is Shanghai Tower.

At 632m it is the world’s second-tallest building and it claims one-third, or 4ha, of its floorplan is “green space”.

Shanghai 1 jpg

Shanghai 1 jpg

Source: Gensler and Thorton Thomasetti

A 15-storey atrium within Shanghai Tower.

This is achieved by utilising the space between the core and the external glass cladding. The building is divided into nine vertical sections of 15 storeys, a design which evolved from China’s fire safety regulations which demand a fire refuge zone every 15 storeys.

At their widest, each 15.24m-wide, 15 storey-tall, light-filled atriums separate the core and the external glass curtain wall. The curtain wall hangs from a floor slab every 15 storeys, via cantilevered outrigger trusses, super columns, and belt trusses.

The curtain wall twists one degree per floor, while central “wedding cake” core and floorplan rise straight.

Interesting shape

“We created a shape that people say is interesting, curving. Difficult? No. It’s not difficult, you just play around with the curtain wall,” says Thorton Thomasetti chief structural engineer for the tower Dennis Poon.

The tallest task of the design was “tuning” this multi-faceted wrapper to prevent movement from temperature, wind or earthquakes.

“We have telescoping joints at each floor, every 15 storeys, to handle the bending movements, horizontal movements,” says Poon. “And each zone is different, so we are fine tuning and accommodating the curtain wall movement at each zone, at each height.”

“In some places the movement is small due to temperature, or big, due to wind or earthquake. We have whole spreadsheets full of numbers to calculate.”

Shanghai Tower Revit Model 1 Thornton Tomasetti

Shanghai Tower Revit Model 1 Thornton Tomasetti

Source: Gensler and Thorton Thomasetti

A computer-generated drawing of the Shanghai tower, minus the outer curtain wall.

Further testing of the tapered, asymmetrical tower focused on defining the optimal shape of the exterior skin in a wind tunnel. Poon says that through trial and error, designers settled for a notch running vertically that disturbs wind turbulence.

One could be critical of the “green spaces”, which in drawings look far from oases, including instead a few planter boxes within a marble floored open space. But Poon says the solution responds to the city’s climate.

“There’s some high rise buildings that put up a lot of hanging plants, growing green plants outside. But Shanghai is a too hot-and-cold area, you can’t grow plants outside so much, it’s also very windy.”

Arcology Tower, Hong Kong

A similar tall building is the Arcology Tower in Hong Kong, designed by architect Weston Williamson & Partners. While this was the result of an architectural competition, and there are no indications that it will be built, it holds similar ambitions for internal gardens, parks and agricultural spaces.

One difference is the way apartments will be linked to the underground rail network – directly via cable-less elevators.

“There are great examples in other parts of the world where large parts of public rail are given over at the base of a tower,” says Weston Williamson partner. Governments and property developers are increasingly waking up to the financial value placed on the proximity and ease of access to transport links.

“Crossrail 1 is now a third paid for by private development, and in Crossrail 2 they’re trying to increase that share,” Williamson says.

arcology tower1

arcology tower1

The Arcology Tower incorporates gardens and agriculture

Cable-less technology enables multiple elevators to run in each shaft, meaning less shafts, less building core, and more floorspace.

Wood says the invention of the steel cable elevator was a key step in tall building innovation, but its time has passed.

“One of the most exciting things in the last five years has been the movement from a rope of steel to carbon fibre – the Ultrarope System. Steel had reached its limit in terms of its weight – it’s impossible, say, after 500m, to pull this single rope,” he says.

Cableless lifts

“This (cableless) technology on the horizon, means the elevator doesn’t need to go purely in the vertical path. Or, taken to the extreme, you could have 100 elevators in just two shafts, and think what that would do to the efficiency of a tall building.”

Beyond the elevator, it is often the management of a tall building’s services that defines its efficiency, in particular, in terms of lighting, air conditioning and heating.

In Sydney, the 155m tall 200 George Street tower designed by architect Francis-Jones Morehen Thorp, features what is claimed to be a world-first closed cavity timber system to conquer this problem. The triple glazed façade holds timber louvres in its outer cavity. The louvres respond to the sun’s movements throughout the day to reduce glare, stabilise temperature and lessen the load on air conditioning.

A handy by-product is that sunlight is reflected off the louvres and into the building providing natural light.

Hero   WW

Hero WW

Source: Francis-Jones Morehen Thorp

“We put forward a vision of a different way of living in an urban high rise development… how you create an interior environment that supports wellbeing – a bit more holistic than sustainability, “ Francis-Jones Morehen Thorp design director Richard Francis-Jones says.

Temperatures inside the cavity can get up to 90ºC under the harsh Australian sun. There was extensive prototyping before arriving at the correct treatment, which removes moisture from the timber.

“One thing this building shows is that we can use traditional materials – wood, stone and glass – in completely contemporary and advanced ways that couldn’t be done 10 years ago,” says Francis-Jones.

Sustainability issue

Wood says the sustainability of tall buildings is an issue. The scale of development over the past 100 years cannot continue, yet buildings are almost inevitably getting ever taller and ever denser.

“We need to increase density and stop using virgin land. So in many respects tall buildings are absolutely the solution.”

He says while tall buildings can be energy profligate at the construction stage, they start to make sense when the high-density housing is considered in context with infrastructure.

“You might have 10,000 people living on those few city blocks, as opposed to 10,000 people out in suburbia, who all need roads, infrastructure, and needing a car to commute and polluting every day.

Detail   WW

Detail WW

Source: Francis-Jones Morehen Thorp

200 George St, Sydney, with its unique timber appearance.

Wood says engineering advances have “enabled” the rise of skyscrapers, perhaps even allowed them to be more inhabitable. But the main driver has been money.

“If ever there’s a part of architecture that’s commercially driven, it’s tall buildings. Behind every skyscraper there’s a company ploughing in a lot of money in the hope that they’re going to get a lot of money back.”

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