Coming Up for Air
Texas Swimming Center, University of Texas at Austin
Mark Spitz's historic performance in the 1972 Summer Olympics sparked a newfound popularity of swimming in the United States. With one of the original university-based aquatic centers to open in the country following these games, the University of Texas at Austin set the bar for such facilities.
Modeling the facility after the Olympic aquatic center in Munich, Germany, the 9-foot deepwater racing pool was designed to be a fast competition pool, devoid of wavy or choppy water. However, 30 years later, the facility was in need of some upgrades both in terms of air quality protection and comfort for swimmers and spectators. With these two factors intertwined, the type of HVAC system installed along with large-diameter, low-speed fans set a new standard for natatoriums around the country.
Host to a variety of events including Olympic trials, national and championship events for USA Swimming and the NCAA, as well as "The Duel in the Pool" between Russia and the United States, the facility is never at a loss for action. Despite the building's constant use, facility managers redesigned and upgraded the entire ventilation system to account for increased temperatures, use and air quality.
Several factors contribute to natatoriums' struggle with air quality. According to Charles Logan, director of the Texas Swimming Center at UT Austin, "One challenge stems from the type of chlorine currently used in swimming pools, and another is the water supply provided by communities."
He added, "Tighter air conditioning systems have decreased air quality, and with bigger events, bigger [AC] loads are put in facilities."
With air conditioning systems being a key player in air quality concerns, Logan installed four large-diameter, low-speed fans in the facility to circulate the air and aid the ventilation system.
The ventilation system within the Texas Swimming Center was completely revamped using computational fluid dynamics (CFD) modeling—a computer simulation of airflow—to help define a system that would best provide comfort as well as improve air quality.
"We used a carbon gas-space filtration, and increased the amount of outside air we bring in, not just recirculate the air we have in there," said Logan. To aid this process PowerfoilX fans from the Big Ass Fan Company were installed throughout the pool complex. "We have a daily setting for these fans, but at night when we don't have anybody in the facility, three things happen," he explained. "Release valves open up in the building, the fans are turned up to full speed, and 100 percent outside air is brought in to flush out all the air that circulated throughout the day."
Over the past decade the cost to condition large natatoriums has increased, sparking interest in finding ways to more efficiently condition these facilities. Ventilation systems are aided by the installation of large-diameter, low-speed fans circulating large quantities of air that allow users to reduce year-round energy usage. In the summer months they provide an evaporative cooling effect, cooling spectators and those milling around the deck.
In facilities that must contend with extreme cold in the winter months, heating system efficiency is drastically improved as well by providing destratification. Heated air from a forced air system (100 to 125° F) is less dense than the ambient air (65 to 75° F) and naturally rises to the ceiling. Large-diameter, low-speed fans reduce temperature variations between the floor and ceiling, mixing the warm air trapped at the ceiling with the cooler air at the pool level. Slowing the speed 10 to 30 percent of its maximum rotations per minute (RPM), the warm air is redirected from the ceiling to the occupant level, increasing patron comfort and reducing the amount of heat loss through the roof. At the same time the fans can be tied in with a facility's automation system allowing facility managers to control all of their energy-heavy systems together, fluctuating along with capacity.
Humidity control is crucial within all natatoriums, regardless of location and size. The mix of chemicals, condensation buildup and patrons themselves creates IAQ concerns that are addressed in a variety of ways including extensive duct systems, exhaust systems and air handling units that create a constant exchange of inside and outside air. With condensation buildup inevitable, large-diameter fans work with ventilation systems to ensure fresh air reaches the occupant level with steady, constant motion. Regardless of the method used to exchange air, it's important to keep it flowing around the water to reduce condensation. According to ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers), room air temperature must be at minimum 2 degrees warmer than the water, to keep condensation in check. (Air, if cooler than pool water, will cause condensation and "misting.")
"We're not the only ones struggling with comfort, a lot of facilities are," said Logan. "We try to garner some of the newest and best technologies, and that's what brought us to the Big Ass Fans." Along with the fans, the entire ventilation system was redesigned to aid in air quality control, regulate chloramines and provide the necessary comfort, with energy conservation in mind.
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