Skyscrapers: the technology of tall is changing

By Sheila Moorcroft

Skyscrapers are getting taller. They are also becoming not only more efficient, but incorporating new approaches to live-ability and sustainability, through new designs and new materials. We may soon be able to open windows on the 25th floor and live in wooden skyscrapers. The changes may make cities more sustainable and enable the east to send design expertise to the west, instead of vice versa.

What is changing?

The world’s buildings are getting taller. By 2020 there will be 10 mega-tall buildings, i.e. over 600 metres, and they will all be in Asia or the Middle East. The title of tallest keeps changing hands, and the latest contender, the Kingdom Tower in Saudi Arabia, will be 1 kilometre tall, if it gets built, as planned, by 2018. In cities such as New York, super-skinny skyscrapers mean that buildings with a far smaller footprint can be squeezed into existing spaces. With smaller individual floors, one tower will have only one apartment per floor, providing 100 penthouses with spectacular 360 degree views of the city, and price tags to match.

A combination of factors is driving the rush for the skies. Economic growth, increased land prices, prestige and rapidly growing urban populations. A host of new designs, technologies and materials is making these various towers feasible and super-efficient. Now the aim is to make them more sustainable and liveable.

The Shanghai Tower will be one of the tallest towers in the world. It has been designed with two skins, wind turbines and high-performance controls. But it also includes garden areas ever 12-15 floors, which will act as neighbourhoods, where people can meet in cafes, small shops and look out over the city. These spaces will also be open to the public, drawing the city into the building.

A second approach aims for liveability and performance. It creates a breathable building, where inhabitants can open windows and feel fresh air – even 25 storeys up. A second skin includes a set of flaps which are controlled to open in optimum conditions to allow passive HVAC and air circulation up through the building. People inside can then open the windows in the inner skin and feel fresh air. A 5-storey, enclosed garden at the top will add to the outdoor feel.

A third example turns a crisis into an opportunity: wooden skyscrapers, using Cross Laminate Timber. The crisis/ opportunity is the infestation of pine beetle in North America which is killing millions of pine trees, which if they were allowed to rot or burn would add about 2% to Canada’s overall carbon emissions by 2020.

CLT has been gaining popularity in recent years. It is made of panels which are as strong as concrete, but can be drilled like wood; they can also be shaped and formed, and pre-fabricated complete with luxurious wood finishes, doors and windows. As a result, they give a softer feel to the structures. The aim is to break through the height constraints – currently around 10-14 storeys – to make wood based skyscrapers feasible. The aim is to reach 40 storeys; a new design system has reached 20 storeys, and is being made open-source.

Implications

Our urban world needs new approaches to building cities, if we are to capitalise on their potential benefits – such as lower per capita GHGs and reduced transportation related emissions. New approaches to construction will be part of that.

The production, transportation and use of concrete alone accounts for an estimated 5% of global carbon emissions. Better ways of building are needed; CLT is seen as a potential alternative.

Skyscrapers are also housing an ever greater variety of functions. We are familiar with offices, shops and homes. Now, vertical farms and gardens are becoming more well-known, but soon there will also be skyscraper schools, cemeteries and even a forest. As we move into ever more vertical cities, we will need to make buildings which are communities in their own right, possibly even protect us from the outside environment.

We are in an urban future. The challenge will be to make it a liveable and sustainable one. Companies which commission buildings create what is often a 100-year legacy. In the interests of the people both inside and outside the buildings, they need to maximise sustainability and live-ability. The growth of cities and mega-tall buildings in Asia and the Middle East may also mean an increasing reversal in design expertise – going from east to west, rather than as it is today, west to east.

For sources and more: http://www.shapingtomorrow.com/home/alert/172311-Skyscrapers–the-technology-of-tall-is-changing

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