March 1, 2008
Plenty of hotel guests or athletic club visitors have smelled the distinct odor of chlorine and other chemicals wafting into hallways from an indoor pool.
For most people, such smells are insignificant or to some, a little unpleasant. However, to a small number of people, these smells can be a major nuisance or even a health risk. That was something the owners of the Oaknoll retirement residence wanted to avoid.
The Iowa City, Iowa, retirement community aims to be one of the nation’s best, and that includes its fitness facilities, which have aquatic exercise and therapy programs.
As part of a 124,000-square-foot expansion, the owners of the 40-year-old facility wanted to tackle three indoor air quality-related fitness center problems: Prevent odors from the pool area from entering other parts of the complex, reduce or eliminate chemical smells in the pool area itself and make the fitness center warm and comfortable without drafts or high humidity.
Avoiding troubleMany pool-related respiratory problems are caused by chloramines, which are byproducts of chlorine-based disinfectants and nitrogen compounds in pool water. Some studies have linked endemic granulomatous pneumonitis, commonly called “lifeguard lung,” to the problem.
The condition, similar to the better-known sick-building syndrome, is characterized by eye irritation, headaches, chest tightness and coughing when around indoor pools. The condition usually improves when exposure ceases. In worst cases, it can cause lung scarring.
The retirement center’s pool includes dozens of underwater, angled spa-style jets, designed to simulate river currents and aid in aquatic exercises. Chemical-free air and easy breathing is essential in such an environment, said Oaknoll wellness coordinator Laura O’Connor.
“From the day we opened the facility, we haven’t had even a whiff of odor in the residence areas or the natatorium (pool area),” added grounds supervisor William Mishler. “The HVAC system design is functioning exactly how the engineer promised it would.”
That engineer was Timothy Fehr of Shive-Hattery in Iowa City, who worked with Bowker Mechanical in Cedar Rapids, Iowa.
In designing previous pool facilities, Fehr had used building pressurization to prevent the spread of chemical-laden air. However, such an approach does not eliminate exposure for those using the pool facilities, except when the air is fully exchanged a few times a year. Fehr decided to use a gas-phase air-purification system to prevent this problem.
New technologyHe had previously used the technology to fix other air-related problems - including at an airport to eliminate jet emissions and near a hospital’s roof - but this was his first time specifying it to eliminate chloramines.
At the retirement center’s recreation building, pool air is re-circulated to a Dectron Inc. Dry-O-Tron DS-102 heat-recovery dehumidifier. It includes a gas-phase air purifier from Circul-Aire Inc., a sister company.
The chloramines particles are absorbed by the Circul-Aire’s Multi-Max media, designed for their removal.
That’s what Fehr likes about the system.
“I like the aspect of packaging the filtration into the dehumidification unit, which creates a single source of responsibility,” he said.
Circul-Aire occasionally tests the media to ensure it’s working properly or should be replaced.
The system removes an estimated 85 pounds of moisture per hour.
Oaknoll’s pool facility has other unusual features. The negative pressure required to eliminate the spread of pool-area air is controlled by a differential-pressure sensor, which communicates electronically with a Summit building-automation system from Trane. The sensor sits in an air-locked area designed by Fehr and Shive-Hattery architect Mark Seabold. It controls a Greenheck exhaust fan and a variable-frequency drive from ABB Inc.
AirflowThe fan, which produces up to 8,500 cubic feet per minute, can be set for maximum airflow during outdoor-air exchanges. At other times, the fan runs at 200- to 300-cfm higher than the outside air supplied by the Dectron unit, ensuring negative pressure.
“Regardless of what’s happening on the supply side and variables such as doors ajar, opened windows, outdoor-air supply fluctuations, dirty air filters, etc., the exhaust fans will always maintain a negative pressure in the space and keep pool air out of the rest of the facility,” Fehr said.
A facility with Oaknoll’s features - a 12-person spa, underwater benches with bubble jets, a three-sided pool deck with radiant heating and a 1,500-gallon pool - has other challenges. Calculating humidity loads and dehumidifier sizing are among them.
The center’s radiant-heat pool deck eliminates the need to install expensive under-deck air to keep windows from fogging over in the winter. It also keeps swimmers’ feet warm.
“I believe the radiant system does a good job at heating the entire window area from top to bottom,” Fehr said. “Putting in a radiant system like this costs more to install and operate, but it again points back to the owners’ mission to eliminate drafts and provide the ultimate in comfort.”
The radiant-heat system was manufactured by Kitec. It uses a plate-and-frame Alfa-Laval heat exchanger, and two 5.7 million Btu Burnham Hydronics boilers. Seabold designed the soffits that hide the center’s aluminum ductwork made by Bowker Mechanical. The soffits use linear diffusers made by Nailor Industries.
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