After more than 20 years of coaching, Queens University (QU) head swim coach Jeff Dugdale has seen his share of coughing, wheezing, and breathalyzers from poor IAQ at indoor swim meets. Dugdale has visited hundreds of natatoriums, and he claims that the new $30 million Levine Center for Wellness and Recreation at Queen’s University in Charlotte, NC, has unprecedented indoor air quality.
Many natatorium IAQ issues are caused by granulomatous pneumonitis or “Lifeguard Lung.” It’s a respiratory irritant caused by long exposures to chloramines, which are chlorine molecules attached to organic chemicals that results in a heavy, toxic gaseous contaminant that stratifies above the water surface in swimmers’ breathing zones. Chloramines are poorly ventilated in many indoor pool environments, according to Dugdale, who quickly reacts with watering eyes and a raspy throat from chloramines exposure.
Minimizing residual chloramines and not cutting corners with the Levine Center’s IAQ-critical ventilation design and equipment specification was the goal of design/build mechanical contractor Lea Burt, P.E., CEM, president of Mechanical Contractors Inc. (MCI) in Charlotte.
Burt’s design features indoor pool dehumidifiers that are Internet-monitored 24/7 for efficiency and indoor air comfort via smart phone by authorized Queens facility managers, MCI, or factory technicians. Burt also specified a built-in deck-level source capture/exhaust plenum-type of device that draws chloramines off the 7,500-sq-ft pool surface and surrounding wet deck surface.
The 144,000-sq-ft Levine Center appears to first-time visitors as a performance basketball arena with three courts, 2,500-seat bleachers, and a high ceiling, however the 33-meter stretch pool in a three-level-deep area is hidden underneath.
“Most universities construct a natatorium with the pool deck on grade, but we designed a state-of-the-art wellness center and built a pool environment and deck that’s 15 feet underneath it,” said Burt.
Another reason the pool goes unnoticed is Levine Center visitors can’t smell pool chemical odors anywhere in the building, thanks to Burt’s mechanical and ventilation design.
The design is anchored by two 24-ton NE-200 Series dehumidifiers manufactured by Seresco USA. The NE-200 Series was originally developed for natatorium retrofits because half the series fits through common doorways. Burt specified the modular system, however, because its small 38-sq-ft footprint helped conserve limited space, fitting better given the three-story building’s small plat and consequential consolidated architectural design.
Deck-level shower rooms span the width of the 22,000-sq-ft natatorium. Burt’s space saving contribution is a 7-ft-high mechanical room mezzanine above the shower rooms, a height that wouldn’t ordinarily accommodate one large conventional dehumidifier.
The piggyback-configured NE-200 Series units are integrated and operate as a 48-ton package with 150 lbs of moisture/hr removal capacity at QU. Because each unit has its own respective fan, compressor, and coil, the facility has redundancy.
“Obviously, there’s a degrading of IAQ if one of the two units go down during a full-load period, but the system’s redundancy is a better option than one large unit going down for service and the space quickly reaching a total air saturation,” said Burt.
Staging is another advantage of modular units. MCI sized the system to handle the expected maximum swimmer load of 75 swimmers in an estimated 300 hrs of annual community swim periods. However, Burt is experimentally programming the control sequence to efficiently stage one unit on for most of the remaining 8,400 annual hrs during lesser loads of swim team workouts or idle nighttime periods, while still retaining the code-required six room air changes per hour, a 50% RH, and pool (82°F) and space (84°F) temperatures. This has proven more efficient than running one large compressor even with a variable frequency drive (VFD), according to Burt.
While the campus-wide BAS manufactured by Tridium monitors the natatorium, Burt relies on the dehumidifiers’ proprietary onboard CommandCenter™ microprocessor for control. Seresco’s free proprietary WebSentry web-based monitoring service sends more than 60 operating parameters daily from both dehumidifiers to Seresco’s factory-based server for daily review by factory technicians.
While most dehumidifiers reject heat to outdoor condensers via refrigerant line sets, MCI specified heat rejection via more environmentally-friendly glycol and dry coolers. The heat rejection system’s long 75-ft piping run from a basement level to the roof, which was the only suitable outdoor location for concealing equipment and preserving the campus architectural aesthetics, surpassed the recommended maximum length for refrigerant piping. Thus, the glycol loop eliminated the potential liability of refrigerant oil migration issues or leaks into the environment. Furthermore, using less expensive glycol versus R-410A refrigerant saved the project tens of thousands of dollars.
To further enhance IAQ, Burt also specified an Evacuator, manufactured by Paddock Pool Equipment Co. The Evacuator is a source-capture system integrated into one width of the pool gutter system for drawing chloramines directly off the pool surface. The 4,500-cfm device’s exhaust is ducted to a fin-tube energy recovery coil manufactured by Trane. The recovery can supplement outdoor air pre-heating or cooling and add to the general exhaust that maintains the natatorium’s code-compliant slight negative building pressure.
Another IAQ consideration is MCI’s specification of a perimeter round aluminum ductwork system by Semco LLC positioned strategically to keep walls condensation free, especially a 3-ft high band of exterior windows. It also distributes the supply air down to the swimmers’ breathing area and to the 150-seat spectator area. More importantly, the aluminum return air louver is positioned and ducted remotely from the supply duct to help draw air across the natatorium and eliminate stagnant air.
“I’ve seen many natatoriums with poor airflow because they value-engineered ductwork to position return and supply air grills together on the same common wall shared by the mechanical room,” said Dugdale.
The natatorium IAQ is so good today that Dugdale no longer sees breathalyzer use. He also steadily sees QU becoming a preferred training site for some of the nation’s elite Olympic hopefuls.