Feature Article - February 2018
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All-Season Structures

Innovative, Nonconventional Structures for Recreation, Sports & Fitness

By Rick Dandes

Creature Comforts

Advances in architectural design and engineering, and the evolving technology of moveable building materials, have made less conventional structures, meant to be a viable, cost effective alternative to a bricks-and-mortar build-out.

The earliest fabric buildings were simple enclosures consisting of little more than a frame and a fabric cover. Today, with rigid frame construction and proven engineering, there are countless fabric building features you can include to suit your needs, such as rooftop solar panels, available for facilities that want to decrease their carbon footprint or go entirely off the grid, Nathan Stobbe said.

"Climate control is necessary in occupied buildings such as sports centers and entertainment venues that require a specific environment," Stobbe added. "Heating, cooling and air conditioning systems along with the tightly sealed building envelope of fabric buildings help maintain a consistent temperature. The non-conductive properties of fabric structures also enhance the efficiency of the fabric structure."

You might not know that you can add both active and passive ventilation options to a fabric structure, ranging from simple mesh eaves for intake to large powered fans, Stobbe said. Ventilation systems help the building breathe and supply a fresh source of cool air throughout the building.

Plastic Fantastic

Architects at Populous are using plastic cladding in their structures. Populous is an international architectural firm, based in Kansas City, with a reputation of building sports structures around the world, including at Sochi, Russia, for the 2014 Winter Olympics.

This particular cladding, ETFE, or ethylene tetrafluoroethylene, is one of the exciting new materials of the last few decades, said Ron Van Sluijs, associate principal at Populous. Van Sluijs, in one of his blogs, went into great detail explaining more about this versatile roof cladding system, which was initially used in greenhouses, but is now an increasingly common feature of stadiums and large atria.

Though ETFE is expensive per square meter, he said, the savings are considerable, because less steel structure is needed and installation time is much faster.

"It's a weather-resistant thermoplastic, which is UV stable with a high light and UV transmittance," Van Sluijs said. "The system is comprised of two or more thin foils sealed around its perimeter, internally inflated to form an enclosed cushion which is then inherently rigid, lightweight, capable of spanning large distances without immediate supports, and also is capable of bearing substantial loads, as well as being self-cleaning … to a degree."

The term "fantastic plastic" comes to mind when working with ETFE, Van Sluijs said. "The material is versatile and can look spectacular, particularly when used as a roof over a large venue. The material is interesting architecturally, structurally, thermally, ecologically, and is likely to be used more and more as a roof cladding option in the future. As a roof engineer and architect, I believe there is also a future for ETFE in public buildings where it can be applied in combination with newer trends such as green-wall-architecture, or as part of an internal atrium, enclosing a semi indoor-outdoor public space while positively adding to the climatic conditioning of the particular space."

Moveable Metal Structures

A retractable aluminum frame structure can also meet your facility needs. "With aluminum frame structures … one of the main benefits is the structure itself can handle, if it is an aquatic facility, all of the chemicals, moisture, condensation and humidity in the air without protection," said Cihan (Geon) Ozdemir, project engineer and owner of a Crown Point, Ind.-based manufacturer of retractable pool and patio enclosures. "From that aspect the structure itself doesn't need to be protected. To take it further, the fact that it is retractable can allow for outdoor use in an outdoor space within minutes and multiple times in a day can be open and closed so you can have that indoor-outdoor facility in one building or with one pool or just with one structure rather than having two separate facilities."

The structure's panels are made of polycarbonate, which does provide a greenhouse effect, Ozdemir said. From an energy-saving perspective this kind of a structure can be a huge benefit.

A retractable frame structure was just the solution decided upon by the town of Highlands, N.C., to enclose a pool. "We had discussed, in year's past, an air bubble," said recreation director Lester Norris. "But for a pool the size we had, a junior Olympic pool, we ultimately did not feel comfortable with that. We looked at an enclosed pool, where just the ceiling would open up. A retractable structure. The one we picked splits in the middle and it opens to where about 80 percent of the pool is wide open. Twenty feet on each end is covered. You also can close it and use it year around."

Consider the entire package of capital cost, reliability, performance long term and engineering safety, as you're looking at the occupancy of that facility."

As for financing, Norris admitted, "we wouldn't have had the money for this, except we had a donor in town who gave us the funds to buy the dome, have it constructed, and make some changes to our pool that would facilitate that.

"The donor stepped up and said, 'I'd like to see an indoor pool,'" Norris said. "We got together with our architect and started doing some investigation, and this was the only product we could find that would cover a pool this size and do what we wanted it to do.

The result is a retractable, aluminum dome. "It's on tracks, it splits in the middle. It is in six sections … it's a stable structure. We love it. Our patrons love it. We advertise it as an indoor pool in the summer. We would do this again in a heartbeat."