New roof technology could benefit a new Rays stadium

Article below about new technology in covered stadia. It is now possible to grow natural grass in covered stadia without the expense of moveable roofs or moveable pitches; see Forsyth Barr Stadium in Dunedin, New Zealand, as the first example of this; a fully ETFE roofed stadium with natural grass growing inside. The below article is a good read if you are thinking about replacing the existing Al Lang Stadium one day with a fully enclosed, natural grass Soccer Specific Stadium (SSS) for the Rowdies in downtown St. Pete. Keeping the fans dry and the games uncancelled due to flooding or lightning, would not be a bad thing for a future Tampa Bay Rowdies SSS. Far too many empty seats at Rowdies games at Al Lang currently due to worries about the weather. 

(Follow link for full article.)    

http://www.tampabay.com/features/humaninterest/new-roof-technology-could-benefit-a-new-rays-stadium/2223706 

New roof technology could benefit a new Rays stadium

Stephen Nohlgren, Times Staff Writer

Wednesday, April 1, 2015 1:08pm

. . .

St. Petersburg built a cavernous throwback to the domed stadiums of the 1970s. Tropicana Field has climate control but at the price of spartan insularity and an artificial turf that wears down players' knees.

Miami opted for a retractable roof, which allows for natural grass and keeps fans comfortable. But that added more than $100 million to construction costs for a roof that stays open an average of 10 games in an 81-game home season.

What if there was another way?

From a cutting-edge arena in Singapore to a luxury commercial development in Miami to the snowy reaches of Minnesota, architects are experimenting with light and wind to create comfy "micro climates'' inside large public spaces. Some are cutting costs to boot.

These innovations could benefit the Tampa Bay area one day. For all our political angst over locating a new baseball stadium, a tougher issue is to come: how to foot the bill.

Less-expensive building techniques that please our senses could work to everyone's benefit, no matter how our protracted stadium debate turns out.

. . .

The roof is made from ethylene tetrafluoroethylene, an intriguing polymer known as ETFE. It is stronger than glass but 100 times lighter. It stretches like a rubber band under pressure, such as from wind or piles of snow.

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

"It's kind of a Minnesota version of an open-air stadium,'' says Michele Kelm-Helgen, chairwoman of the Minnesota Sports Facilities Authority. "We looked at retractable roofs, but we were concerned that given our climate, we may not have cause to open the roof that much."

A glass wall at one end of the roof has 100-foot pivoting doors that let in fresh air and breeze. "Even in the wintertime, you feel like you are outside, but you will be warm,'' Kelm-Helgen says.

. . .

ETFE construction typically features at least two membranes separated by air pockets a foot deep or more that create an insulating pillow effect. Sometimes a middle layer is added, Wright says, with air pressure valves that move it up or down, allowing computers to alter the degree of shade as the sun moves across the sky.

. . .

"ETFE is a good material. If you understand where the air comes in and where to force it out and how to keep the air moving, you are not going to create a greenhouse,'' says Soligo. "If people really want an open-air feeling, you can do a lot for them.''

Singapore, about 85 miles from the equator, has humidity you can slurp. Yet one end of its new 55,000-seat National Stadium remains open to the city even when its retractable ETFE roof closes for games.

Rather than cooling the entire stadium, designers installed air-conditioning vents under each seat. A digital ticketing system turns them on only when people are sitting in the seats. Cool air flows down to the playing field so competitors don't get heat stroke. As air eventually warms, it rises and escapes through vents in the roof.

Energy costs are 60 percent below those of conventional methods.

. . .

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

A lighter, fixed roof might bring that cost down, says Mike Wekesser, lead designer on Target Field and now sports design director of the architectural firm AECOM.

Retractable-roof designs create lots of weight with the roof itself, the trusses the roof moves on and the mechanisms that propel it, requiring heftier supporting columns and foundations.

"Miami is an enclosed stadium with a hard deck and (is) air-conditioned. It is designed that way,'' Wekesser says. "You could bring down the cost — I don't know by how much — by using lighter material. You would bring down the tonnage of steel, and in Tampa Bay, concrete. It is one of the biggest costs in any stadium.''

Brickell City Centre's Climate Ribbon will cost $30 million and cover 150,000 square feet, which makes it about half as big as the Marlins Park roof for one-quarter the cost.

. . .

Still, "I think you can find a way to put a skin on a new ballpark that does not have to be retractable,'' Wekesser says. "The roof could be more like a canopy or umbrella, with side ventilation so air could pass through. The edges could be opaque enough to get shade. It could have that open-air feel of old-time baseball.