Swimming Pools

Natatoriums, or indoor pools, follow local code limits on air intake and room temperature. Owners have the final say on space temperature, but ASHRAE and local code recommendations guide design.

Critical to successful design is good Indoor Air Quality (IAQ), achieved by mixing outdoor and filtered return air. Local codes, often following ASHRAE standard 62, dictate the amount of outdoor air to be introduced.

Ensuring occupant comfort is key, typically achieved by maintaining the room's air temperature slightly warmer than the pool water temperature, usually by 2-4°F, reducing evaporation.

SHR 1400

This Heat Recovery Ventilator (HRV) emoves the humidity from the exhaust air and tempers the supply air by transferring sensible energy between the air streams. 


Ensure consistency

Large hotel pools to competition/diving pools/indoor water parks need a significant amount of ventilation.

Indoor pools, classified as class 2 air by ASHRAE 62.1 2019, have moderate contaminant levels and mild odors, unsuitable for recirculation.

That said, ventilation systems must introduce outdoor airflow at an acceptable temperature to manage costs and enhance comfort.

A good system:

Maintains humidity at 60% in summer, 50% in winter

Meets local outdoor airflow codes

And ensures constant, comfortable temperatures

The importance of ventilation and temperature regulation cannot be understated. Too much humidity can eventually cause building issues. Heat loss from the introduction of outdoor air should also be considered for cost factors.

By prioritizing these points, building professionals can deliver a natatorium that's not just aesthetically pleasing, but also healthy, comfortable, and cost-effective in the long run.

Headshot of Amir Refaat
Amir Rafaat
Product Manager

Regulations and Factors

Important to know
  • ASHRAE 62.2 Dictates minimum ventilation rates in specific types of breathing zones.

  • Local Codes May have adopted 62.2 or have their own regulations.

  • Code Compliance and Efficiency Adhering to codes ensures safety and minimizes costs through energy-efficient solutions.

  • Moisture Control Keeping RH% at or above 50 is ideal.

  • Maintenance Can be kept to a minimum with a specialized ventilation system.

  • Air Quality Enhancement Eliminate odor, preserve infrastructure, and provide a comfortable environment to occupants.

  • Ventilation System Integration An AHU can easily be integrated however the designer chooses.

  • Noise Installing in a mechanical room ensures the noise is contained in an area away from occupants.

  • Health Risks Proper ventilation mitigates mold growth, viruses, and bacteria in the air, promoting a healthier environment.

Chloramine Challenges

Indoor swimming pools have a smell that most say comes from chlorine. However, chlorine is not distinctly strong enough for humans to smell unless at or above toxic levels. The smell comes when chlorine and organics (sweat, oils, and urine) mix in the water. This smell is known as chloramines, which are volatile.

Product rendering of a Geniox Large

Competition/Diving pool or Indoor Waterpark


Systemair’s premier air handling unit gives designers many options. With airflows ranging from 440–65,000 CFM, and a ZM 310 corrosion class C5 metallic coating, it is quite suitable to handle over 100,000 sq. ft. in indoor spaces. 

How to Size Ventilation Systems for Indoor Swimming Pools

What to know

ASHRAE 62.1 states that the CFM per ft2 must be 0.48. For example, a 2,700 ft2 hotel swimming pool would need to have at least 1,296 CFM of outdoor airflow.  

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