How HVLS Fans Support Healthy Aquatic Environments

Although natatoriums, otherwise known as indoor swimming pools, are a great place to race during a meet or enjoy an afternoon swim, the aquatic environment demands a thoughtful building design and proper maintenance. Aquatic center owners and operators will find that two facility management concerns – chloramines and condensation – can be minimized by using HVLS fans.

Common Natatorium Air Quality Concerns

The most common air quality concern stems from using chlorine to treat pool water. Chlorine disinfects to protect the health of swimmers, but when it combines with organic pollutants in the water (sweat, oil, etc.) it creates chloramines. Chloramines, not chlorine, are responsible for the well-known “pool smell”. Even more concerning than the smell is the fact that chloramines can pose health risks as they build up and become airborne. Symptoms of overexposure to chloramines include irritated eyes, nose, mouth, and lungs.

Another facility management concern is condensation. Indoor moisture levels are high in natatoriums making the surfaces prone to condensation. Particularly in cold climates, condensation is likely on the windows, doors, and even in the walls and roof. Frequent and prolonged condensation causes biological growth and corrosion.

Why Airflow is Critical in Natatoriums

Good air quality is important to swimmers and spectators, and it’s also a national concern. In 2014, the U.S. Department of Health and Human Services’ Center for Disease Control and Prevention released its Model Aquatic Health Code (MAHC).

In Section 4.0, the MAHC lays out many air handling system requirements for natatoriums. High Volume, Low-Speed fans help achieve these requirements by accelerating the air turnover rate by thoroughly mixing the air. There are three MAHC directives that HVLS fans help accomplish:

1. Condensation Prevention:

“Indoor aquatic facility building envelope construction shall include a vapor retarder/insulation arrangement to assist in preventing the condensation of water on inside building surfaces under the coldest outdoor conditions.”

Natatoriums are often humid. They have a high dew point, meaning that there is a high concentration of water vapor in the air. If this air, heavy laden with water vapor, meets a cooler surface, it will deposit the moisture on that object, creating condensation. Facilities with prolonged condensation issues will experience biological growth and corrosion of their building materials. HVLS fans offset humidity by homogenizing the air thereby equalizing the temperature, minimizing moisture deposits, and speeding up the drying process.

2. Consistent Airflow:

“Indoor aquatic facility air handling system shall be designed to provide consistent airflow through all parts of the indoor aquatic facility to preclude stagnant areas.”

Stagnant air is problematic for three reasons: firstly, natatoriums have building requirements for the amount of time it takes to turn over all the air in the space. If there are stagnant areas, this requirement is not being met. Secondly, inadequate air circulation makes swimmers and spectators uncomfortable. Thirdly, stagnant air lends itself to condensation buildup. HVLS fans eliminate stagnant air by delivering consistent airflow throughout the facility and accelerating the air turnover rate.

3. Airflow Across Water Surface:

“The Air Handling System shall be designed considering airflow across the water surface to promote the removal of disinfection by-products (chloramines).”

After chlorine combines with the organic pollutants in the pool, it becomes a chloramine and hovers over the water. Chloramines are four times heavier than standard air. How do you pull something so heavy up and out through an exhaust system? In short, you increase airflow across the pool surface. HVLS fans deliver large volumes of air at adjustable speeds to move the plume of chloramines up to the exhaust system.

HVLS Fans - Designed for Natatoriums

1. Large Fans for Large Spaces:

An Olympic-size swimming pool is 50x25 meters. So, multiply the pool size by three to know the space needed for the pool deck, spectator seating, changing rooms, and equipment areas. It’s a very large area!  Given that large area, HVLS fans can produce huge columns of air to move air throughout. The largest HVLS fan is 24-feet in diameter and generates 365,000 cubic feet of air per minute.

2. Corrosive Environment:

HVLS fans should be able to tolerate wet and corrosive environments like indoor aquatic facilities. Moisture may seep into those poorly designed fans and damage the electronics, making them useless. In fact, an HVLS fan should be rated IP65 or higher to avoid these issues. Products with this IP rating are sealed against dust and moisture. What's also key to preventing deterioration is, fan components (like connecting hardware) should be stainless steel. It is also important to choose blades made of anodized aluminum, not raw aluminum.

The Bottom Line

HVLS fans promote healthy aquatic environments by completely circulating the air in the facility. Thoroughly mixing the air further equalizes the temperature, minimizes moisture deposits, and speeds up the drying process. The airflow from HVLS fans also quickens the air turnover rate by eliminating stagnant air and moving chloramines up to the exhaust system. All in all, HVLS fans help aquatic center owners and operators provide a fun, safe, and comfortable environment for swimmers and spectators.