NASA lands in Minnesota
Space-age clear roof panels in new Vikes home to let sun in.
Ethylenetetra
It’s not one of quarterback Teddy Bridgewater’s audible calls, nor is it a term for a three-receiver set in the Vikings offense.
Look higher for the clues to this tongue-twister, all the way up to the roof of Minnesota’s new stadium.
Sixty percent of the venue, 248,000 square feet of it, will be covered by this transparent material called ETFE. The space-age product, scientifically categorized as a copolymer plastic, lets in light like glass would. It’s just lighter, cheaper and cleaner.
Public financial support for the project was never going to prevail unless the facility was usable year-round for a variety of events, so an open-air stadium wasn’t a viable option. A retractable roof would have cost more.
So the Vikings entered a new era of transparency: The $1.076 billion US Bank Stadium will open next season, boasting the only ETFE roof on a sports facility in the United States.
“Clear is the new retractable,” Vikings executive vice president for stadium development Lester Bagley said.
The transparent roof will be complemented by five 95-foot-tall pivoting glass doors on the front of the building, letting fresh air in on warm days.
In a northern climate where sunny autumn afternoons are savored, natural light was a high priority.
The memory of the Teflon-covered Metrodome was still fresh.
“This’ll be one of those well-recognized buildings in the industry,” said Kevin Taylor, the senior vice president at HKS Architects, who’s managing the project. “We think the perception of sitting in a facility enjoying a game when it’s either raining or snowing outside and still feeling like you’re experiencing an outdoor stadium is going to be phenomenal.”
There are a handful of ETFE buildings in America, like a train station in Anaheim, Calif., and an amphitheater in Kansas City, Mo., but this will be the biggest.
ETFE was developed by DuPont in the early 1970s as aeronautics insulation. Tested to withstand hurricanes, ETFE was used in Europe in the 1980s for malls, zoos and schools. TheWater Cube in Beijing, used for swimming at the 2008 Olympics, became the largest building to use ETFE.
The panels being used on US Bank Stadium average 10 feet by 300 feet. The ETFE material is in thin foil sheets just a fraction of an inch thick. There are three foil layers in each panel, with low-pressurized air in between for a total width around 25 inches.
“You think about that actually resisting all of the climate conditions of Minneapolis, and it’s quite impressive,” said Edward Peck, a vice president for Thornton Tomasetti, the structural engineering firm for the stadium.
The Metrodome collapsed under the weight of a 17-inch snowstorm in 2010. Plus, ETFE is more acoustically reflective than Teflon, so this place could be even louder than the Metrodome.