Billed as “America's largest indoor water park,” the new 70,000-sq-ft Wild Water-Dome at Wilderness Hotel & Golf Resort in Wisconsin Dells, Wis., presents a host of indoor-air-quality (IAQ) challenges. The presence of hundreds of thousands of gallons of water, splashed around by wave machines, water cannons, and the like, can create rainforest-like conditions. Combine that with the airborne byproducts of pool-water sanitizing chemicals, and IAQ becomes vital to patron comfort.
Working with the engineering department of fabric-duct manufacturer DuctSox, Jason Beren, PE, vice president of operations for Kilgust Mechanical of Madison, Wis., designed six 120-ft-long runs of 60- and 66-in.-diameter TufTex premium-grade fabric duct. Orifice diameters range from ¾ in. to 1½ in., with various duct-circumference placements. The two perimeter runs, positioned 19 ft above the floor, have two linear arrays of orifices directed toward the windows and another array directed toward the deck.
Using fabric duct allowed Beren to select the throw, direction, and volume of airflow for each section. This allowed a target airflow of 75 to 100 fpm at the pool-deck level. The thousands of orifices engineered into the duct meet the needs of the structure while providing a gentle flow of air to occupants, who otherwise easily could be chilled by drafts. The even distribution also helps eliminate air stratification in the far corners of the space.
The orifices also help to evenly draw airflow off of the Texlon transparent roof system from Foiltec North America.
Ventilation rates were fine-tuned and confirmed during design with the aid of computational-fluid-dynamics analysis performed by building physicist Matthew Herman of Buro Happold Consulting Engineers in New York.
The fabric duct cost an estimated $230,000 less in material and labor than metal duct would have, Beren said. For example, the fabric duct's comparably lighter weight eliminated forklift and mechanical-boom-lift rental fees, saving more than $10,000.
“Fabric duct resulted in a huge HVAC savings,” Beren said, “but equally important was the fact the fast-track project's ductwork-installation time was cut nearly in half.”
The surface of the fabric duct, which is devoid of ribbing and protruding registers, offers an aesthetic alternative to spiral metal ductwork.
“We're really pleased how it performs and looks, especially the custom earth-tone color that coordinates with the rest of the space,” Raymond E. Bolton, AIA, principal of Architectural Design Consultants Inc. of Lake Delton, Wis., said. “It's designed to resist corrosion, so it's really a good choice for this type of space.”
Wilderness took advantage of Duct-Sox's new silk-screening program. Logos of Wilderness restaurants are silk-screened on the ductwork.
Four XeteX Inc. ventilation units produce a total of 220,000 cfm of capacity. There is no dehumidification, as in typical natatoriums, but, rather, a reliance on outside-air supply and exhaust, with four to six air changes per hour, depending on the season.
Summer operation features 100-percent untreated outside air and rapid air changes. Large natural-ventilation openings, such as oversized doors, windows, and louvers, reduce energy consumption. That, combined with good air distribution, helps reduce the accumulation of chloramines.
During winter, seasonably dry out-side supply air is pre-heated and mixed with warm, humid pool-room return air to achieve a comfortable relative humidity. If return-air heat recovery is insufficient, the ventilation units' direct-fired burners will heat air to temperature set points.
The large solar gain the facility receives from its glass roof aids the wintertime space-heating effort.
Adding to the system's flexibility and energy efficiency are variable-frequency drives from ABB.
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