Willdan understands that warm, moist natatorium environments place special demands on the HVAC system and building envelope. We design tailored solutions to address the unique challenges found in natatoriums including inadequate outdoor air, air stagnation, poor air distribution, high humidity, mold, mildew, condensation and corrosion. Four key airside design elements include:

Air Distribution - The poor movement of fresh air over the pool surface, combined with the use of air recycling devices to control heating costs, leads to poor air exchange.

Outdoor Ventilation Air - Outdoor air is critical to diluting airborne chemicals and maintaining good indoor air quality.

Exhaust Air - Exhaust air intake grilles located directly above a spa or whirlpool capture and extract the highest concentration of pollutants before they can diffuse into the space and negatively impact the room air quality.

Air Change Rate - ASHRAE recommendations for proper volumetric air changes per hour are important, ensuring that the entire room will see air movement.

At Hood River Aquatic Center, Willdan conducted an energy audit of the entire facility and recommended installing a solar water heating system along with a new condensing boiler to achieve optimal air circulation and temperature control for the 43,000 people who swim laps, take classes, compete and have fun throughout the year. The solar system includes 2,300 square feet of solar collectors installed on a portion of the facility roof; another part of the roof can be removed during warmer summer months. When the system was installed in 2006, it was one of the largest solar water-heating arrays in the Northwest.

“From March through October, solar is the primary (and often the only) heating source for the 281,000-gallon recreation pool,” says Mark Kinzer, Willdan’s Project Manager and Design Engineer. “After September, the solar system is turned off and drained, and the new high-efficiency condensing boiler takes over.” These improvements save about $17,000 in energy costs per year.

In addition to the significant decrease in natural gas use, our upgraded solar and boiler system requires far less maintenance than the aging boiler it replaced, saving me thousands of dollars and countless headaches.

-Scott Baker, Assistant Director, Hood River Valley Parks and Recreation

Poor water chemistry is the single biggest source of indoor air pollution and corrosion problems. Chemical off gassing from the pool water causes indoor air quality (IAQ) issues in a natatorium, resulting in a chlorine smell or other foul odor in the pool area, improper pool pH levels, and the accumulation of total dissolved solids. 

“Pool deck air temperature is just as important as the water temperature, so the aquatic center also tackled its air heating system,” Kinzer points out. “Contractors insulated the single-wall ductwork from the HVAC system. By replacing the damper actuators and installing variable-frequency drives on the supply and return fans, the center gained better control over air coming in and going out of the building.” Previously, the fans were either fully on or completely off. Now, the system conserves energy by regulating air turnover to meet the specific needs of the building at different times of day or seasons of the year.