Editor's Note: Three World Cup 2014 stadiums in Brazil are using the Birdair technology detailed in the 2012 article below: Estadio Mineirao in Belo Horizonte, Estadio Nacional in Brasilia, and Arena Fonte Nova in Salvador.
Birdair completed this structure for the Denver International Airport in 2004. The facility shows off the artistic potential of the fabric: here, the peaks and valleys in the roof were inspired by the Rocky Mountains.
› Link to larger photo
The Georgia Dome's roof lets in a large amount of natural light while reflecting much of the Sun's heat. It showed its strength during a 2008 tornado, sustaining only minor damage and keeping occupants safe.
› Link to larger photo A Super-Durable Material Designed for Space Suits is a Natural in Advanced Architecture
On a Friday night in March 2008, fans at a college basketball game at Atlanta's Georgia Dome noticed that the scoreboard was beginning to sway. Unknown to those in the stadium, a tornado was ripping through downtown. The safety of the more than 18,000 people would depend in large part on the integrity of the stadium's domed roof-built using a material originally developed to protect NASA astronauts.
Over 40 years ago, engineers at NASA were hard at work developing the next generation of space suits. The suits required material that would be durable, strong, lightweight, flexible, and noncombustible. They settled on a fiberglass fabric coated with polytetrafluoroethylene (PTFE), more commonly known as Teflon.
The resulting material proved noncombustible and durable enough for NASA's needs. While the current NASA space suits have evolved beyond the PTFE fiberglass fabric, the original innovation is still very much in use, having become a unique component of advanced architecture.
Birdair Takes Off
In 1956, aeronautical engineer Walter Bird founded Birdair Structures Inc. in the kitchen of his home in Buffalo, New York. Soon after, Birdair collaborated with the companies who had partnered with NASA and developed a modified, stronger version of the space suit material.
The resulting product allowed Birdair to create a market for lightweight tensile membrane structures for roofs, skylights, and canopies.
"When there are so many architectural materials out there, fabric is not something architects usually think of offhand," says William Barden, Birdair's director of architectural development. "Walter Bird's pioneering role in the tensile structure industry was to take a technology that was perceived by people as 'pie in the sky' and create a market for it."
The same qualities that made the PTFE fiberglass fabric appealing to NASA also make it ideal for large scale, permanent tensile membrane roofs. The material is pound-for-pound stronger than steel while weighing less than 5 ounces per square foot. It offers up to 24 percent solar translucency, letting in lots of natural light. At the same time, it provides as much as 75 percent solar reflectance, keeping out heat and making it an energy-efficient roofing alternative. It is also cost effective due to its durability and low-maintenance characteristics.
Making a Lasting Impression
Birdair's PTFE fiberglass membrane entered the Space Foundation's Space Technology Hall of Fame in 1989. Nevertheless, the material's capabilities and possibilities have yet to be exhausted. In 2008, the company's Sheerfill Architectural Membrane was approved by the U.S. Environmental Protection Agency as an ENERGY STAR qualified roof product and recognized by the Cool Roof Rating Council, based on the fabric's high solar reflectance and thermal emittance.
Birdair's structures can now be seen all over the world in stadiums and arenas, transportation hubs like airports, retail and commercial buildings, and entertainment and leisure facilities. The company continues to work on new projects: Its structures were used in three out of the four primary stadiums for the 2010 World Cup in South Africa, as well as the new Dallas Cowboys stadium.
Its fingerprint on large structures will likely pass the test of time, too: The Georgia Dome came out of the March 2008 Atlanta tornado with only slight damage to its roof, and not a single injury to its occupants, even though 135 mph winds caused significant destruction in the rest of the city. The roof's fiberglass membrane, the same material that once protected astronauts in the harsh environs of the Moon, required only minor repairs.
Teflon® is a registered trademark of E. I. du Pont de Nemours and Company. ENERGY STAR® is a registered mark owned by the U.S. Government.
To learn more about this NASA spinoff, read the original article from Spinoff 2009.