Walls of Glass

  • By Anna Rothschild
  • Posted 08.25.11
  • NOVA

The glass faíçade, or curtain wall, of One World Trade Center does far more than let light into the building. In this short video, learn how state-of-the-art glass panels covering the tower offer strength, safety, and beauty to the new skyscraper.

Running Time: 02:26


Walls of Glass

Posted: August 25, 2011

NARRATOR: The design of One World Trade Center presents an architectural dilemma: How do you build a tower that is startlingly beautiful, but also strong and safe?

The answer? Glass.

The walls of the building will be made of floor-to-ceiling panes of glass—a design called a curtain wall. But this is no ordinary curtain wall. It will use 12,000 glass panels in aluminum casings. The glass alone will weigh 15 million pounds. Each panel will have to bear about 6,000 pounds of pressure, essentially the weight of two cars! And the panes will be huge, reaching up to 10 by 12 feet.

Glass may seem like a weak building material, but with the right handling, it can be really tough. To strengthen it, each pane of glass is subjected to 1,150-degree heat. The heat tempering makes it capable of resisting 100 mile-an-hour winds, torrential rain, or anything else nature throws at it. The glass is also extensively tested, to make sure that each panel is the right thickness and strength for where it will sit on the building.

Also, when it comes to safety, One World Trade Center's curtain wall has a secret weapon—a new type of polyurethane coating. When the coating is sandwiched between two pieces of glass and heated, it helps prevent the wall from shattering, even in the event of a blast from a powerful explosion.

The coating also has another purpose: to ensure that the building doesn't get too hot. After all, a tower covered with 700,000 square feet of glass is bound to soak up a lot of heat from the sun.

The special coating lets light in, but keeps heat out, lowering lighting and air conditioning costs. It's one of the ways this building will be super green and LEED certified.

Of course, in the end, visitors to New York won't see how green, or safe, or strong this curtain wall is. They'll just see its breathtaking beauty.


Production Credits

Video short produced and edited by
Anna Rothschild
Original footage
© WGBH Educational Foundation 2011
Additional footage
Silverstein Properties, Inc.

Image and Stock Footage Credits

(main image: glass panels)
© WGBH Educational Foundation 2011
© thebadastronomer/ flickr.com
© omergenc/istockphoto.com
© Tim Berners-Lee/"W3 future directions" keynote 1st World Wide Web Conference, Geneva, May 1994
(check mark)
Public Domain

Sound Effect Credits

(beep sound)
© han1/freesound.org
(boing sound)
© schluppipuppie /freesound.org
(cash register sound)
© creel23/freesound.org
(fire sound)
© dynamicell /freesound.org
(shuffle sound)
© deathpie/freesound.org
(squish sound)
© Corsica_S /freesound.org
(stretch sound)
© hyo /freesound.org

Public domain music courtesy archive.org

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