Facilities: Hard-to-pronounce materials defining the new stadium
Facilities: Hard-to-pronounce materials defining the new stadium. Even though ethylene tetrafluoroethylene (ETFE) may sound like something Mary Poppins would come up with, it will undoubtedly play a significant role in the construction of the new NFL stadiums planned for Chicago, Nashville, and Buffalo.
ETFE, a synthetic weather-resistant material stretched over an open span, is being utilised more and more in stadium construction. It is particularly popular as a cheaper alternative to domes and retractable roofs.
Since its use on the canopies of major stadiums like U.S. Bank Stadium, SoFi Stadium, and Allegiant Stadium became widely known, ETFE has experienced a large increase in its market share. The Tennessee Titans, one of the clubs in the process of constructing a new stadium, has announced plans to use ETFE to enclose their proposed new stadium, making it possible to host events all year long, such as basketball.
Declaration
Nowadays, “if a building is going to have a roof on it in some way, it’s going to have ETFE on it somehow,” as Dan Wacker, Mortenson’s director of preconstruction, put it.
Over the past century, scientists and engineers have made great strides in the development of synthetic polymers such as ETFE and its close relative PTFE (full name: polytetrafluoroethylene, also known by the brand name Teflon), but only recently have they begun developing their own unique formulas for use in sporting arenas.
“It’s like a platform that you can innovate on,” said Phil Kolbo, principal and senior architect at Populous. “You’re not buying off the shelf; you’re making what you need.”
Tensile membranes have the ability to be used in any and all aspects of a building, including roofs, in place of glass windows, and covers over luxury areas like seating basins. They are also lighter and less expensive than steel.
Buffalo, which has already committed to an outdoor stadium but doesn’t want to give up its late-season home-field weather advantage, might benefit from the latter idea by installing a tensile canopy system around the field to shield spectators from the snow.
According to Wacker, “when you talk about the fan experience on open-air facilities, historically NFL stadiums haven’t had canopy coverage.” However, “Europe is replete with these PTFE roofs that shade the supporters,” the Major League Soccer (MLS) is aiming for 100% coverage of its fans, and I believe that the National Football League (NFL) would consider clubs utilising that as an alternative.
Freedom of form
Anything with two sides can benefit from a tensile system, be it a backyard, a premium stadium bar, or a sports arena’s roof.
According to David Peragallo, sales and specification manager, Americas, at the French firm Serge Ferrari Group, the flexibility of tensile materials allows designers to incorporate complex curves and shaping that would be impossible, or at least very costly, with traditional steel and metal panel roofs.
According to an email from Peragallo to Sports Business Journal, “[Tensile materials] provide architects and designers of sports stadiums a unique freedom of shape and flexibility to take their concept to the next level.”
The low coefficient of friction and hydrophobicity of TFE materials make them simple to clean and unaffected by environmental factors like heat and sunlight. PTFE is more effective for shading structures like canopies due to its mesh structure and lower transparency than ETFE; however, ETFE is more advantageous for totally enclosing and conditioning a building.
ETFE, like other tensile fabrics, can be used to cover a roof without the requirement for as much structural reinforcement.
Statement
According to Wacker, the long-span steel used to support a stadium’s roof can be anywhere from 600 to 800 feet in length, making it the most expensive portion of the stadium. Many NFL stadiums don’t have retractable roofs, including the high cost of installing them (especially if they are made of steel) and the risk of damage to the structure from repeated retracting and extension.
One of the first large stadiums in the United States to install an ETFE roof in 2016 was Minneapolis’s U.S. Bank Stadium. The ETFE alternative provided the Vikings with “retractability” without the cost of a retractable roof, saving the team about $100 million, according to Kevin Taylor, principal and sector manager, venues, for architecture firm HKS.
Remark
Leading designer Taylor noted, “We spent a lot of time making sure we could get a lot of natural light coming into that stadium.” This was true with AT&T Stadium, U.S. Bank Stadium, and SoFi Stadium. I knew it would happen on other projects when we did it on “Vikings.”
ETFE and related materials are more lightweight than glass, making them suitable for vertical use. This is why PTFE was ultimately chosen for the concourse at Globe Life Field in Arlington rather than ETFE.
Let’s make it
SoFi Stadium is a canopied facility, like a stadium perched beneath a single-layer ETFE “carport” held in place by substantial cabling, in contrast to the fully enclosed U.S. Bank Stadium. To prevent snow buildup in the winter, U.S. Bank Stadium’s roof features a three-layer cushion system (the sheets of ETFE are inflated).
The installation of a cushioning system was also crucial to ensuring that Allegiant Stadium complied with local building codes by blocking out UV and IR radiation. That, as Kolbo pointed out, is one of the difficulties of utilising ETFE. Frit, however, can also be used to block UV or infrared light from entering a material (like ETFE) because of the pattern or ink it imprints. And there are new items on the market with Low-E coatings that can filter infrared rays like a thicker pane of glass.
Kolbo clarified, “We didn’t go, ‘oh, it’s a cool material, let’s use that. ‘Hey, this is what we want to accomplish,’ we declared. We need it to be reflective, laminated, and transparent. Let’s go out and get these things since these are the things that we want.