New roof technology could benefit a new Rays stadium

Minor league baseball can tolerate muggy open-air stadiums in Florida. If rain or lightning wipes out $ 1 on Tuesday, who cares when the average attendance drops from 1,300 to 900?

The stakes in the major league are higher. Forget nostalgic ideas about baseball under summer skies. Fans who spend $ 40 on a ticket and a beer want protection and comfort. As a result, the Miami Marlins and Tampa Bay Rays play in air-conditioned indoor stadiums, a situation that is neither enjoyable nor cheap.

St. Petersburg built a cavernous throwback to the 1970s dome stadiums. Tropicana Field has air conditioning, but at the price of a spartan island location and artificial turf that wears the players’ knees down.

Miami opted for a retractable roof that allows natural grass and provides comfort for fans. But that added more than $ 100 million to the cost of building a roof that would stay open an average of 10 games in a home season of 81 games.

What if there was another way?

From a state-of-the-art arena in Singapore to a luxury commercial development in Miami to the snow-covered areas of Minnesota, architects are experimenting with light and wind to create a comfortable “microclimate” in large public spaces. Some cut the cost of getting started.

These innovations could one day benefit the Tampa Bay area. Despite all of our political fear of finding a new ballpark, a more difficult problem is about to come: how to pay the bill.

Cheaper construction techniques that please our senses could work for the benefit of all, regardless of how our lengthy stadium debate develops.

See the light

Minneapolis these days has a catchy slogan: “Sure is the new retractable.”

The city decided to replace its aging domed stadium that was used by the NFL Vikings after snow collapsed the roof. The new venue, which is currently under construction, has a solid, sloping roof that blocks the elements while allowing light to pass through.

The roof is made of ethylene tetrafluoroethylene, a fascinating polymer called ETFE. It’s stronger than glass, but 100 times lighter. It extends like a rubber band under pressure, e.g. B. by wind or piles of snow.

Most importantly, manufacturers can embed ETFE with tiny dots that filter sunlight and lower temperatures. The result shadows the fans, but still lets them see the sky, clouds and the surroundings from outside.

“It’s kind of a Minnesota version of an open-air stadium,” said Michele Kelm-Helgen, chairman of the Minnesota Sports Facilities Authority. “We looked at retractable roofs, but we were concerned that given our climate, we might not have this.” cause the roof to open that far. “

A glass wall at one end of the roof has 100-foot revolving doors that let in fresh air and breezes. “Even in winter you feel like you’re outside, but you get warm,” says Kelm-Helgen.

Bruce Wright, a professor at the University of Minnesota who specializes in lightweight building materials, compared the effect to that of a city bus covered with a thin advertising sheet.

“People can’t look inside and you’d think it would be like a tunnel inside,” says Wright. “But from inside you can see very clearly. It blocks the sun, but not the view.”

The ETFE construction typically has at least two membranes separated from one another by air pockets a foot or more deep, creating an insulating cushion effect. Sometimes a middle layer is added, Wright says, with air pressure valves moving them up or down so computers can change the degree of shadow as the sun moves across the sky.

Light patterns are reversed at night. Passers-by can peer into the stadium for an iconic glimpse of a huge community. Fans see a dark roof, but can still see the downtown skyline through the glass wall.

stay cool

When the Rays proposed a new stadium on St. Petersburg’s waterfront seven years ago, the site was too narrow for a retractable roof. Shade and protection would have come from a “sail”, a movable canopy that extended to a huge tower on the other side of the field.

The project continued for many reasons, including skepticism that the ocean breeze could make fans comfortable.

Now a $ 1 billion development south of the Miami River goes one step further.

Brickell City Center, three blocks from Biscayne Bay, markets jet-set luxury. Offices, condominiums, restaurants and a shopping center are connected by a “Climate Ribbon”, a cover made of wavy fabric and glass that provides shade for visitors, guides rainwater into cisterns and creates a mini wind tunnel underneath. Strategically placed angles and louvers are what Chris Gondolfo, Vice President of Swire Properties, the developer, says will capture and divert even the slightest breeze from the water.

“It’s like in older houses with a chimney,” says Gondolfo. “The airflow is constantly being flushed through something.” It’s kind of like a 6 to 8 knot breeze, even on the calmest day. ”

Part of Brickell Place is outdoor dining in August.

“People want the experience of being outside and not having the mechanical comfort that comes with air conditioning,” says Michael Soligo, CEO of RWDI, the wind consultant on Climate Ribbon.

A clear roof stadium could also channel wind, says Soligo, who has worked on dozen of stadium projects, including sails.

“ETFE is a good material. If you understand where the air goes in and where it needs to be pushed out, and how to keep the air moving, you won’t be creating a greenhouse,” says Soligo. “If people really want an open one.” -Air feeling, you can do a lot for her. ”

Singapore, about 85 miles from the equator, has humidity for you to sip on. One end of the new national stadium with 55,000 seats will remain open to the city, even if the retractable ETFE roof is closed for games.

Instead of cooling the entire stadium, the designers installed air conditioning vents under each seat. A digital ticketing system only switches them on when people are sitting in the seats. Cool air flows to the playing field so that the participants don’t get heat stroke. When the air finally warms up, it rises and escapes through ventilation slots in the roof.

The energy costs are 60 percent below those of conventional methods.

Dollars and cents

Major League Baseball’s two newest stadiums offer a sense of how much a retractable roof adds to construction costs.

Target Field, an open-air stadium in Minneapolis for the Minnesota Twins that opened in 2010, cost around $ 400 million, excluding land or infrastructure. Two years later, Marlins Park was $ 520 million. The stadiums designed by Populous are similar in size and configuration. The main difference is the retractable roof.

When Tampa Bay residents speculate about the cost of a new Rays stadium, the marlin’s $ 520 million is often tossed around as a minimum starting point.

A lighter, solid roof could cut those costs, says Mike Wekesser, lead designer at Target Field and now sports design director at AECOM architecture firm.

Retractable roof structures add a lot of weight with the roof itself, the trusses the roof moves on and the mechanisms that propel it, requiring heavier support columns and foundations.

“Miami is a closed stadium with a hard deck and (is) air-conditioned. It is designed that way,” says Wekesser. “You could cut costs – I don’t know how much – by using lighter materials.” . They would cut the tonnage of steel and, in Tampa Bay, concrete. It’s one of the biggest costs in any stadium. ”

The Brickell City Center’s Climate Ribbon will cost $ 30 million and cover 150,000 square feet. That makes it about half the size of the roof of Marlins Park for a quarter the cost.

Wekesser warns against simple comparisons.

Baseball stadiums have quirky shapes with long trusses to support each roof, he says. Some interiors, such as B. Luxury suites always require air conditioning. Allowing enough light to support natural grass could prevent fans from getting enough shade. And in Florida, hurricane standards come into play.

“I think you can find a way to put a skin on a new ballpark that doesn’t have to be retractable,” says Wekesser. “The roof could look more like a canopy or an umbrella, with side ventilation to allow air to flow through.” by. The edges could be opaque enough to get shadows. It could have that open air feel of old-time baseball.

“A bit like sunglasses, but very light sunglasses.”

Contact Stephen Nohlgren at [email protected] Follow @snohlgrentimes.

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