Improving Your Natatorium’s Environment: Creating Healthy IAQ

Tags: , ,

When you go to an indoor pool, what do you first notice? We often first feel the warmth and humidity, and then smell something that resembles a strong chlorine odor — although it’s not actually chlorine. Actually caused by chloramines (combined chlorines) off gassing from the pool’s water surface, this odor is the by-product from chlorine disinfecting the water of dirt and organic material, and is a sign that the pool’s indoor air quality (IAQ) is struggling. As these pollutants are unhealthy to breathe in and are corrosive to metal in the facility, poor natatorium IAQ poses both health and operational consequences. 

Healthy Indoor Air Quality (IAQ) Matters

Your natatorium’s environment is a key aspect of having a safe and efficiently-operating aquatic facility. Designing the natatorium experience for people visiting, swimming and working at your facility is of the utmost importance; think of children taking swim lessons, the swim instructors, swim teams competing for an entire day and the lifeguards that watch over during that time.  Maintaining great IAQ is a balancing act, and no single system or product will give you that alone; it takes an integrated approach where the elements of your air and water systems work together.  

When designing a natatorium, the relative humidity, air temperature, pool water temperature, pool activity levels, air distribution, outdoor air, exhaust air and pool water treatment are all key aspects that must be addressed to provide a good environment. At Pure Water Aquatics we focus on integrating these elements to create the healthiest, most long-lasting indoor pool for all parties — the owners and operators, swimmers and spectators. In this article we cover a few main elements that contribute to healthy IAQ for your natatorium environment, and what to consider when designing your HVAC system for your natatorium environment. 

There are many factors impacting Indoor Air Quality, but in this article we will be covering these two key factors that have a direct impact on IAQ: 

  • Pool water chemistry 
  • Poor air distribution

Pool Water Chemistry

By maintaining optimal pool water conditions you will have the best possible indoor air quality and ensure optimal performance from the mechanical system. Ultraviolet light (UV) treatment of pool water has shown to have a very positive impact on the water chemistry and can help reduce waterborne chloramines. However, it is important to note that UV cannot remove chloramines that are already airborne. This is why it is important that different parts of your total system work together.

Remember that strong odor caused by chloramines we spoke about in the beginning? To avoid chloramines, it is imperative to maintain proper free chlorine and pH levels. Test your water regularly for chlorine, pH, calcium hardness, phosphates and total alkalinity.

Jacob James, Energy Engineer and certified Energy Manager, writes, “Building controls can now seamlessly connect and optimize the vast majority of natatorium equipment. For example, a UV system can now increase or decrease its output (dosage) as directed by the chemical controller, a relatively new capability in the marketplace.”

Additionally, we’ve worked with aquatic facilities to integrate controls that were once operating independently from each other. This helps the system you have in place to become more efficient, saving you time and money. Jacob adds, “Integrating these new control systems presents significant opportunity to improve building performance. In fact, natatoriums that have installed system-wide controls systems have seen their operating costs go down while creating a healthier space for their pool patrons.”

Pool Air Distribution

The proper balance of outdoor air, room exhaust air, and air movement at the water surface is crucial to ensuring chemical concentration levels are maintained within acceptable levels. To minimize evaporation and balance air movement at the water surface, your HVAC system should be configured to pull air across pool water surfaces.

Additionally, ASHRAE calls for maintaining the natatorium air temperature at two to four degrees above the pool water temperature and not above 86 degrees F. By doing so we’re trying to balance HVAC equipment size and the energy costs of maintaining conditions in both natatorium and water. 

ASHRAE also recommends the relative humidity in a natatorium be maintained between 50% – 60% relative humidity. Lower relative humidity increases operation costs because of increased evaporation, while also causing swimmer discomfort due to evaporative cooling from their bodies when they get out of the pool. However, the higher the relative humidity is, the greater the risk to the building structure.

The Elemental Approach

We understand that maintaining healthy IAQ can feel anywhere from frustrating to downright overwhelming and stressful, but it doesn’t have to be that way. Excellent IAQ is a key building block of our Elemental Approach, where we analyze your facility’s overall natatorium environment by breaking it down into small elements. Healthy air quality is just as important as clear water, and with our Elemental Approach, we do a deep dive into all of the tools and processes your facility uses to contribute to your IAQ and clear water. From there we create customized solutions specific to your pool’s operating system and design. 

When designing and managing your HVAC system, proper commissioning and taking into account the many factors of IAQ will help create a sustainable and efficient operating system for your natatorium environment. We will be covering more of these factors — including outdoor air ventilation, exhaust air, air change rate — and commissioning, in our upcoming blog posts as a part of this series well.


This article is the beginning of an ongoing series for enhancing your natatorium space. If this brought up any questions, or if there’s anything you’d like to read, learn or hear more about, visit our contact page or drop us a line at Subscribe to our emails in the upper right hand corner to get this information sent directly to your inbox as well.