MINNEAPOLIS — A new era — in Vikings football and Minnesota history — is dawning.
The Vikings will celebrate the ribbon cutting and grand opening of U.S. Bank Stadium today with a ceremony inside the 1.75-million-square-foot facility.
The state-of-the-art venue has a capacity of 66,655 on Vikings game days. There will be numerous other events throughout the year, but U.S. Bank Stadium hosts one welcome guest — natural light — every day.
Patterns of light enter the building in the early mornings and late in the day through a clerestory window that circles the perimeter.
The newly installed Gjallarhorn had a particular glow about it when Chad Greenway stepped up to its platform on Thursday morning.
As the sun angle becomes more vertical, light shines through the south-facing, clear ETFE material that covers 60 percent of the roof. As the sun moves west, the wall of glass that faces the Minneapolis skyline again changes the experience for those in the building.
Builders have paid attention to the sun and its patterns to guide them for centuries, but technological innovations that include 3D and 4D computer modeling are allowing architects to deliver designs based on detailed information.
John Hutchings and Lance Evans, architects with HKS, utilized technology throughout the design process to predict the light and shadow patterns, but also to understand the way the sense of scale for the building that is nearly twice the size of its predecessor, the Metrodome (900,000 square feet), in one of the most urban landscapes in the NFL. They were able to detail relationships of another downtown building down to a particular seat, as well as light patterns that a fan in a particular seat can expect throughout an evolving season.
The architects showed sun studies from the preseason to the playoffs, for noon, 3 p.m. and night kickoffs and "everywhere in between."
"We knew it would be a diffused light, not a harsh light," Hutchings said standing on the turf near the 30-yard line, west of midfield on Tuesday. "You get shadows when the sun is out, so it's nice."
Vikings Owner/President Mark Wilf said Thursday that the outdoor feel indoors is his favorite characteristic of the stadium.
"There are a lot of things, but for me, what strikes me the most is when you walk in, you're in an indoor venue but you feel the outdoors and it's got that indoor-outdoor feel from the ETFE roof to the world's largest pivoting glass doors, the entire experience is special," Wilf said. "You know where you are at all times, you know the weather, you know you're in the City of Minneapolis, but at the same time, you're in the comfort of an indoor building, so that's what stands out to me."
For all of the information that HKS was able to gather, predict and present, there is something special about experiencing it for Evans.
"We promised to the client that we'd create an outdoor stadium for them without all of the problems that causes and without all of the expense of doing an operable roof," Evans said. "Seeing the effect the ETFE has and how it connects straight down to the west wall and the way that that daylight kind of throws itself into the bowl and lights this space was our number one design goal in the beginning and something the Vikings desperately desired. I think we were able to provide it."
The design used 200,000 square feet of custom glass that was made in Owatonna, just 65 miles south of the stadium, and 248,000 square feet of ETFE on 60 percent of the roof.
While the roof and the west wall have been the most publicized, Hutchings said the less-publicized clerestory window "does marvelous things."
"Early in the morning, you can see shards of sunlight in the east and the same thing in the evening from that clerestory glass on this side."
The design lets in more natural light than a stadium with a retractable roof, which would have been cost prohibitive here because of snow and wind load requirements in Minnesota, Hutchings and Evans said. Both men worked on Lucas Oil Stadium for the Colts and AT&T Stadium for the Cowboys.
While both have roofs that open and close, they don't have the Legacy Gates — glass-clad doors that are 55-feet wide, 95-to 75-feet tall, and contain 10 standard doors apiece — of U.S. Bank Stadium.
"There's nothing like it in the world, so once they open up, I think people of the state are going to be ecstatic about that indoor-outdoor feel," Hutchings said. "When you can't have a retractable roof, you just get the biggest doors in the world."