How the high-profile skyscraper flourished after 9/11

The attack on the Twin Towers 20 years ago did not lead to the demise of tall buildings. Instead, skyscraper construction is booming. Several trends now shape the rise of the ‘supertall'

The 20-year anniversary of the collapse of the World Trade Center towers in New York has jogged some uncomfortable memories. At the time, 9/11 seemed to mark the end of the age of the skyscraper. Many in the building industry believed that people would no longer feel comfortable living, working and socialising in these potentially high-profile targets. However, this could not be further from the truth.

According to the Council on Tall Buildings and Urban Habitat (CTBUH), 84 per cent of current skyscrapers have been built since 2001, with 112 being built a year in the last 10 years compared to only 12 a year in the decade leading up to 2001.

‘Gone are the days where supertalls were reserved for office space…’

Before 2001, almost half of all skyscrapers were located in North America. However, with the continued growth of developing countries and regions like China, India and the Middle East, North America now only accounts for 15 per cent of supertall buildings.

The use of skyscrapers is also changing. With growing populations and a strain on living space, cities have had to adapt quickly to meet demand. Therefore, skyscrapers are increasingly being developed as residential or mixed-use buildings. Gone are the days where supertalls were reserved for office space. According to a report in Dezeen, several trends are shaping the ever-changing world of skyscraper design.

Advances in engineering

Advances in structural engineering have, in recent years, enabled architects to reach record heights. For example, the Burj Khalifa located in Dubai and designed by Adrian Smith reaches a staggering height of 828 metres and has been the world’s tallest building for the past 11 years. This building is part of a growing design trend described as ‘The race to the sky’.

More and more ‘megatalls’ – buildings which exceed heights of 600 metres – are being developed. Projects such as Kingdom Tower in Saudi Arabia are on track to exceed 1,000 metres in height. However, in China, this trend came to an abrupt end when it banned the construction of buildings higher than 500 metres as part of its sustainability goals. This has put into question how long this trend will continue on for.

Wrapped in glass

The modern skyscraper is now defined by clean-cut glass facades. Eight of the top ten tallest skyscrapers are wrapped in large expanses of glass. This design trend allows for better-lit interiors and spectacular views, but these buildings are energy inefficient due to them requiring high levels of air conditioning. Some developers have suggested that this trend may not last much longer due to the increased public awareness of the need to protect the environment.

As architects shift their focus from designing single-use to mixed-use skyscrapers, The Shard in London is a good example of how office design and skyscraper use has changed in the last 20 years. The Shard has residential, office and commercial spaces and is described as a unique community in the sky. As demand for more flexible space grows, it’s unlikely this trend will die out.

Pencil towers and sky bridges

Another trend is the emergence of ‘Skinny Skyscrapers’ also known as pencil towers. These buildings are often found in densely populated areas where building space is limited such as in Hong Kong or  Manhattan. As population levels have exploded in recent years, this trend will increase despite some  disenchantment with city living as a result of pandemic.

Free-form structures have also become a popular trend in skyscraper design. The rise of twisting skyscrapers has been partly driven by technology and sustainability, as a contorted forms can lead to more aerodynamic and energy-efficient structures. Their contemporary design also attracts tourism and breaks up the often monotonous city skyline.

Sky bridges connecting skyscrapers in the air is another trend that has boomed in the last 20 years. Perhaps the most famous example of a linked skyscraper is the Marina Bay Sands resort in Singapore. Sky bridges are often a valuable way to save space in densifying cities.

Vertical farms

An increasingly popular trend in concept designs is to use skyscrapers as vertical farms by incorporating hydroponic farming technology into their structures. Carlo Ratti Associati is currently designing a 218-metre-tall skyscraper in China that would use hydroponic farms to produce 270 tonnes of food per year and feed roughly 40,000 people.

Incorporating greenery into building design is perhaps the latest trend when it comes to skyscrapers. Using greenery can promote biodiversity, improve air quality nd create cooling islands whilst also helping to reconnect city-dwellers with nature. Stefano Boeri’s Bosco Verticale high-rise incorporates as many trees as could be planted in one hectare of forest. However, these trends have been criticised as a poor solution for the environmental problems supertalls can cause.

Overall, although the trend of designing the tallest and grandest of skyscrapers is far from over, skyscraper design is now increasingly influenced by the drive to reduce our impact on the environment. This trend will almost certainly outlive the desire to build ever-taller skyscrapers.

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