Page 20 - AUA TRAVLLER

Innovative roof makes
Minnesota stadium lighten up

IT’S not one of quarterback Teddy Bridgewater’s

audible calls, nor is it a term for a three-wide 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 colossal venue, some 248,000
square feet of it, will be covered solely by this trans-
parent 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 go- One of the ETFE pioneers was the founder of the Ger- of the ship-shaped building would provide as much
ing to prevail unless the facility was usable year-round man company Vector Foiltec, which was selected as the sunshine for the seats as if the whole top was covered
for a variety of events, so an open-air stadium wasn’t a manufacturer for the US Bank Stadium roof. with ETFE.
viable option. The retractable roof would’ve cost more, The Water Cube in Beijing, used for swimming at the So about that weather.
but the Vikings realized through researching other NFL 2008 Olympics, became the largest building to incor- The Metrodome, remember, collapsed under the
venues that roofs are rarely retracted enough to make porate ETFE. There’s Allianz Arena in Munich as well weight of a 17-inch snowstorm in 2010.
them worth the extra expense. as a couple of soccer stadiums in New Zealand, where With an asymmetrical design and a catch-basin gutter
So the Vikings entered a new era of transparency: The Taylor visited shortly after HKS got the Minnesota system around it, this roof will be far better equipped
$1.076 billion US Bank Stadium will open next season, project. Taylor was joined on that trip by Edward Peck, for heavy snow. There’s also a system of thin cables to
boasting the only ETFE roof on a sports facility in the a vice president and facade specialist for Thornton help support the ETFE panels.
United States. Tomasetti, the Chicago structural engineering firm “You won’t see them sitting in the stands,” said Brendan
“Clear is the new retractable,” said Vikings executive for the stadium. Moore, the senior project manager of the building’s
vice president for stadium development Lester Bagley, The panels being used on US Bank Stadium average 10 enclosures for Mortensen Construction, the general
repeating a slogan coined as the design was revealed feet by 300 feet, so only 75 will be needed to maximize contractor of the project. “While this is very unique to
more than two years ago. transparency. The ETFE material is in thin foil sheets Minnesota and North America, this is not the first time
The transparent roof on the south side will be comple- just a tiny fraction of an inch thick. There are three that ETFE has been used in a cold-weather environ-
mented by five 95-foot tall pivoting glass doors on foil layers in each panel, with low-pressurized air in ment by any means.”
the front of the building, letting actual fresh air in on between for a total width around 25 inches. There’s one unknown left, and that’s the noise.
warm days. With high-definition televisions at home “You think about that actually resisting all of the cli- ETFE is considered more acoustically reflective than
serving as stiff competition for ticket sales in a northern mate conditions of Minneapolis, and it’s quite impres- Teflon, so this place could be even louder than the
climate where sunny autumn afternoons are savored, sive. It’s due to its physical strength but also its ability Metrodome.
natural light was a high priority. The memory of the to kind of elastically respond to things,” Peck said. “We may not know ultimately until our first game, but
Teflon-covered Metrodome, cozy and quirky but dingy, The upper layer of foil is fritted to limit the greenhouse we believe and have been advised that this building
was still fresh. effect, and the air helps maintain the desired thermal will be loud and bring that home-field advantage we
performance. Light studies of the site conducted by want,” Bagley said.
“The easy way out would have been a simple roof,” said HKS concluded that 60 percent usage on the south side Even in defeat, though, the sun will shine.
Kevin Taylor, the senior vice president at HKS Archi-
tects who’s managing the project for the Dallas-based Monday, July 20 2015 - ARUBA TRAVELLER
firm. “This’ll be one of those well-recognized buildings
in the industry. 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 experienc-
ing an outdoor stadium is going to be phenomenal.”
There are a handful of ETFE buildings around the coun-
try, like a train station in Anaheim, California, an am-
phitheater in Kansas City, Missouri, and a waterpark in
Wisconsin Dells, Wisconsin, but this will be the biggest.
ETFE was originally developed by chemical company
DuPont in the early 1970s as aeronautics insulation.
Tested to withstand weather from hail to hurricanes,
ETFE began to be used in the 1980s for structures like
shopping malls, zoos and schools, primarily in Europe.

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