Chloramines considerations
Besides condensation, chloramines, which are the heavy gases resulting from chlorine molecules bonding with body contaminants such as perspiration, urine, or fecal matter, are a major concern in natatorium ventilation. There are many incidents of poor indoor air quality, typically from chloramines, endangering respiratory systems both short-term and long-term.
In 2013, Caeleb Dressel, who later became a gold medal swimmer at the 2016 Olympics, was carted off to an emergency room with breathing issues later blamed on chloramine accumulation at the Speedo Winter Junior Nationals at the North Carolina-based Greensboro Aquatic Center.5
Source capture units that come integrated into one side of the pool gutter (in new construction) or as a portable poolside plenum near one side of the pool, are excellent remedies for minimizing chloramines. They not only draw chloramines off the pool surface, but also exhaust them outdoors. Source capture units integrated into the gutter can also return the captured air to the mechanical air handler for energy recovery to efficiently pre-heat or pre-cool the ASHRAE Standard 62.1 mandated percentage of outdoor air required for natatoriums.
Source capture units also fit nicely into the overall design of return air and maintaining the building at a negative pressure so natatorium air is not pushed to other parts of the building. Return air grills work best at low positions to draw air off the occupied breathing zone on the pool surface and deck; however, high positions can function well, too, by eliminating stratification in the space. Multiple return grills, positioned low and high will help complete air changes.
The design and location of the air distribution system supply, return, and exhaust grills, as well as source capture units, should be integrated to achieve the most favourable results. The design capabilities and flexibility provided by fabric duct make it a great choice for the air distribution system in natatoriums.
Other benefits fabric duct offers versus metal
Besides the aforementioned benefits, fabric duct is approximately 90 per cent lighter than metal. This facilitates safer installation in new construction projects, especially with large diameter ducts that are difficult to hoist and install onto high ceilings. For projects retrofitted from metal to fabric, such as the earlier mentioned Northern California municipal pool, the roof’s structural integrity is not an issue. Likewise, older indoor pools originally designed without any ductwork can be retrofitted to fabric duct with no concerns about fortifying the roof to accommodate the weight of metal duct.
Keeping ductwork free of corrosion and evenly dispersing air across condensation-prone surfaces and down to the occupied breathing zone are key to improving natatorium indoor air quality.
Philip Daugherty is the engineering manager for FabricAir, a Lawrenceville, Ga.-based manufacturer of fabric air dispersion duct for heating, ventilation, and air conditioning (HVAC) applications. He has been with the company for eight years and is responsible for training, product innovation, installation guidance, and troubleshooting. The FabricAir engineering department can guide any aquatic manager or engineer through the natatorium ventilation design process for new construction as well as metal-to-fabric retrofits. Daugherty holds an engineering degree from the University of Georgia. He can be reached via email at phd@fabricair.com.
