The One World Trade Center might be the most expensive skyscraper in history, but the mighty concrete tower is also one of the safest and most sustainable
Designed by architect David Childs of Skidmore, Owings & Merrill (SOM), the monumental building replaces New York’s Twin Towers, which were destroyed by the devastating terrorist attacks on September 11, 2001. It is central of the World Trade Center (WTC) redevelopment in lower Manhattan, New York.
One World Trade Center features a vast lobby and a twisting geometrical tower that tapers as it rises towards the two-level observation deck and restaurants. It terminates with an illuminated spire. Costing $3.9 billion, the tower is the most expensive skyscraper in the world to date, but is also one of the most technologically advanced and environmentally sustainable.
Occupying the north-west corner of the WTC site, One World Trade Center sits next to Snøhetta’s National September 11 Memorial Museum and the memorial designed by Israeli-American architect Michael Arad of Handel Architects. While the memorial and museum look to remember the past, SOM’s tower was intended to symbolise the future.
Construction began in April 2006 and the building took seven years to compete, finishing in July 2013. It opened to its first tenants in November 2014, 13 years after the 9/11 attacks.
After some controversy over whether the spire at the tower’s peak could be included in its final height measurement (officially it is included), One World Trade Center is recognised to be the tallest building in the Western Hemisphere at 541 metres. Its height in feet, 1776, is a deliberate reference to the year that the United States declared independence.
Without the 124 metre spire, the building stands at 417 metres high, the same as the original Twin Towers.
Many people mistakenly associate the design of the tower to Daniel Libeskind, who was responsible for the WTC’s 2003 masterplan when the proposed building was still nicknamed the 'Freedom Tower'. Libeskind designated where all the buildings would sit, and worked with SOM on a design that was never implemented. The concept for One World Trade Center underwent several revisions.
After a controversial redesign by Childs, the design was further revised in 2005 when the New York Police Department expressed concerns over the safety of the glass lobby. Their initila suggestion featured a protective concrete wall, that was criticised for looking too military. SOM absorbed the concrete wall into the design and added a veil of glass fins to the concrete walls.
The tower stands on a podium with a 3,700-square-metre footprint that is identical to that of architect Minoru Yamasaki’s original Twin Towers. 4,000 low-iron glass fins are positioned at various angles to form a regular pattern that reflects the light and disguises the security barrier of thick, blast-resistant walls that surround the cubic base of the building and the huge 20-metre-high public lobby.
From the base, the tower’s square edges are chamfered back, transfiguring the squared base of the podium into eight elongated isosceles triangles. In the middle, the tower creates a perfect octagon and then culminates in a stainless steel parapet. The entire tower is clad in glass, creating a surface that appears like a kaleidoscope – refracting the sunlight and changing weather.
The core of the building has metre-thick concrete walls that contain the stairwells, elevators, gas and water lines, communication systems, dedicated fire stairwells and an emergency lift for firefighters.
Sustainability was a big concern for the architects and One World Trade Center received an LEED Gold certification in September 2016. The design aims to improve environmentally friendly measurements across a range of metrics.
The extensive glass walls allow 90 percent of offices within the building to benefit from natural light, reducing the demand on electrical lighting. At the same time the glass is specially coated to minimise unnecessary heat gain from the sunlight. Rainwater is harvested and used in the buildings cooling towers and in the irrigation of onsite landscaping.
Many of the materials used in construction were recycled, included 95 percent of the structural steel and the green concrete is made from waste ash from coal plants. The iron needed to support the glass facades was also significantly reduced, reducing material demand and improving the views from the windows. Around 80 percent of waste products accumulated in the building are recycled.
In May 2015 the tower’s One World Observatory opened, offering 360-degree views of New York and New Jersey from 380 metres up in the air. It contains three restaurants and an exhibition called Voices, plus a Sky Portal that shows live video footage of street level.
Visible from 20 miles away and Child’s intended that it would echo the tall triangular forms of other New York icons such as the Chrysler Building and the Empire State Building, making it an organic part of the city's celebrated skyline despite its extreme height. Whether it suceeds in achieving this, of course, only time will tell.