When it comes to IAQ, there are a lot of mechanical engineering challenges in a huge indoor waterpark setting such as the Wilderness’ new 70,000-square-foot Wild Waterdome. Just the presence of hundreds of thousands of gallons of water splashed around with wave machines, water cannons, water slides, and patrons can create rainforest-like conditions. Combine that with airborne byproducts of such a facility’s necessary pool water sanitizing chemicals and IAQ becomes vital for patron comfort.
But despite these IAQ challenges, the Wild Waterdome is a breath of fresh air in Wisconsin Dells, which is the world capital of waterparks with over 20 facilities. Designed by mechanical contractor Kilgust Mechanical, fabric ductwork plays one of the important roles in the successful IAQ of the Wild Waterdome.

Working with the engineering department of fabric duct manufacturer, DuctSox, Dubuque, IA, Jason Beren, P.E., vice president of operations, designed the airflow around six 120-foot long runs of 60-inch and 66-inch diameter TufTex premium grade fabric duct including variety of orifice diameters ranging from 3/4-inches to 1-1/2-inches and various duct circumference placements. The two perimeter runs, positioned19-foot-above the floor, have two linear arrays of orifices directed toward the windows and another array towards the deck.

Typically indoor waterparks use coated spiral metal duct with relatively few large diffusers to direct enough air movement towards the windows to reduce condensation. This design is acceptable for industrial situations, however, in occupied spaces, the higher velocity drafts may be uncomfortable for patrons, especially where wet body surfaces can easily be chilled by drafts. Using fabric allowed the designers to select the throw, direction and volume of airflow per section, allowing a target airflow velocity of 75 to 100 feet/min. at the pool deck level. The thousands of orifices engineered into the fabric duct meet the needs of the structure while providing a gentle airflow to occupants. The even distribution also helps eliminate air stratification in the far corners of the space, which is a common problem in larger spaces.

The computer aided design (CAD) orifice placements also help evenly draw airflow off the Wild Waterdome’s unique Texlon Transparent Roof System.

These intricate ventilation rates were fine tuned and confirmed during Kilgust’s design process with the aid of a computational fluid dynamics (CFD) analysis.

On the economic side, fabric duct saved the project an estimated $230,000 in HVAC costs according to Jason Beren, Kilgust’s vice president of operations. Just the fact that fabric duct’s comparably lighter weight eliminated expensive forklift and mechanical boom lift rental fees saved the project over $10,000.

“Fabric duct resulted in a huge HVAC savings, but equally important was the fact the fast-track project’s ductwork installation time was cut nearly in half,” said Beren.

From an architectural standpoint, the streamlined fabric surface that’s void of typical ribbing and protruding registers offers an aesthetic alternative to spiral metal ductwork. “With no prior fabric duct experience, we were a bit skeptical in the beginning,” said Raymond E. Bolton, AIA, principal, Architectural Design Consultants Inc. “But we’re really pleased how it performs and looks, especially the custom earth tone color that coordinates with the rest of the space. It’s designed to resist corrosion so it’s really a good choice for this type of space.”

Additionally, the Wilderness took advantage of DuctSox’s silk screening. With dozens of competing restaurants in the Wisconsin Dells area, the Wilderness subliminally directs patrons to its own restaurant facilities with silk-screened logos of each venue appearing on the ductwork surface that’s in full view of all Wild WaterDome’s patrons.

As waterpark design evolves into the 21st Century, design/build companies such as Kilgust have become leaders in mechanical design innovations such as fabric duct and their unique air dispersion capabilities.