This article was originally published in Parks and Recreation magazine, the official publication of the National Recreation and Park Association. Read it here.

With their array of unique comfort, safety, and performance considerations, indoor aquatics facilities are one of the most challenging and complex building types to design. Natatorium design must carefully balance many factors, including user safety and comfort, energy consumption, and operational and accessibility objectives. Here are some key criteria to consider for a successful aquatics facility design.

HEALTHY USER EXPERIENCE

User safety is the paramount design criterion. Water quality, air quality, lighting, and material selection all play a role in creating a safe and comfortable indoor pool environment.

Water Quality

Pool water quality is the key to maximizing user safety and comfort, as well as the driving force for reducing energy consumption. High pool water quality is controlled by water filtration equipment that filters out contaminants and chemical treatment systems, like chlorine, that kill germs and bacteria.

There is a wide variety of filtration and chemical treatment systems on the market that are customized to the size, shape, and aquatics program for every natatorium. While sand media filters have dominated the marketplace for years, regenerative media filters are emerging as a preferred choice that uses approximately 90 percent less fresh water, 50 percent less energy, and 30 percent less chemicals.

For large competition aquatics venues, adding ultraviolet light (UV) water treatment systems is the new standard. UV systems provide crystal-clear water and virtually eliminate the need for chemicals.

Air Quality

Air quality within natatoriums is directly related to pool water quality because it is laden with vapor from the pool water’s evaporation. The natatorium air we breathe is critical to maintaining a healthy atmosphere, illustrating the delicate relationship between pool water quality and the indoor atmosphere.

The air temperature in natatoriums should be two degrees Fahrenheit higher than the pool water temperature, and relative humidity needs to be maintained at 50 percent to 60 percent. This balances the need to reduce pool water evaporation and condensation on surfaces as much as possible. The distribution of conditioned air should be concentrated on the pool decks, where the users are, with low return to capture chloramines, and high return over the pool water to maintain a positive airflow.

The HVAC (heating, ventilation, and air conditioning) units for natatoriums are highly specialized. Dehumidification units with heat recovery are designed to handle the highly vaporized atmosphere and then remove the latent heat and use it to heat the newly conditioned air in cold months. In warm weather, they switch to an economizer fresh air mode. It is highly recommended that the design team perform a Computational Fluid Dynamics (CFD) analysis to ensure effective air circulation. Be aware that the pool atmosphere must be kept under negative pressure to minimize water vapor penetration to adjacent spaces.

Lighting Design

Lighting design has a direct impact on patron safety and comfort. Given their large volumes, natatoriums require a lot of lighting. A combination of natural and artificial lighting is recommended for indoor aquatics facilities to enhance safety and reduce operating expenses. The best distribution of artificial lighting is at the pool perimeter above the pool deck. This approach makes it easier for maintenance, reduces water glare, and enhances lifeguards’ ability to see trouble. Windows should be located high enough to prevent glare on the water surface.

When designing aquatics facilities, material selection must delicately balance patron safety and ease of maintenance. Slipping on a wet pool deck or locker room floor is a common event that can lead to major injury. Pool decks and locker room floors should, therefore, be slightly textured to reduce this fall possibility, but not so much that it impairs deck drainage or is uncomfortable to walk on. Several options are available, such as 2×2 ceramic tiles or cementitious finishes that enhance sure footing. Selections of pool deck finishes must have a slip resistance of 0.50 to 0.55 minimum DCOF (dynamic coefficient of friction) per ANSI A326.3 or 0.60 preferred.

Because of all the hard surfaces, acoustic controls are also essential for aquatic facilities. Several sound-absorbent materials, such as lapendary panels and moisture-resistant fiberboard, resist the vapor-laden air.

ENERGY AND WATER CONSUMPTION

Indoor aquatics facilities consume more energy than almost any other building type. To mitigate this significant energy use, sustainable design criteria should be an integral part of the building design process.

Energy Use Intensity (EUI) is a standard measure of energy usage in building design. The target EUI for aquatics facilities with 75 percent wet spaces should range from 120 to 140 kBtu/ft2 EUI. Credits are available for a variety of sustainable strategies, including the use of renewable energy sources, high-efficiency ERU units, and the utilization of natural lighting. When renewable energy sources like photovoltaic panels or geothermal are used, EUI could decrease to 80 to 100 kBtu/ft2.

Natural lighting integration can reduce energy consumption dramatically while contributing to a safe and healthy atmosphere. The right natural lighting strategy can eliminate the need for artificial lighting all day long. Staging artificial lighting levels for different instruction, recreation, and high-competition venues can also save significant operational costs.

Water consumption reduction can result in reduced environmental and operational impacts. High-efficiency pool water filtration systems that have lower backwash demands, humidity controls, low-flow showers, and low-flow flushing fixtures all can contribute to achieving this objective.

OPERATIONAL AND MAINTENANCE CRITERIA

Selecting effective materials is an essential part of the aquatics facility design process. Not only must these facilities beat back the weather on the exterior, but they must also withstand significant water and chemicals on the interior. These factors affect every surface, structural element, and moving part of the building.

Structural elements like steel trusses must receive special coatings to resist the penetration of water vapor and condensation from reaching the steel, which will result in the structure’s deterioration.

Concrete must be treated with special coatings to prevent water vapor from reaching the reinforcing bars.

Heavy timber structures promote lower embodied carbon and lower maintenance costs in pool environments. Wood structural elements, however, seal themselves. The outside one-eighth inch of wood reacts in tandem with the water vapor to seal itself. After years of use, the virgin wood inside the section is as structurally sound as the day it was cut.

Doors and door frames deteriorate quickly in wet areas. All doors and frames in these areas, including locker rooms, should be made of aluminum, stainless steel, or fiberglass. This guideline is especially true in the pool pump and chemical storage rooms.

Renewable energy sources like photovoltaic systems can also contribute to lowering the energy profile of aquatic facilities.

Fabric ductwork is a cost-effective alternative to exposed spiral aluminum ductwork with minimal maintenance requirements.

ACCESSIBILITY AND PRIVACY

Accessibility requirements are magnified in aquatics facilities where locker rooms play a key role in the user experience. The locker room layout should be clear upon entry and avoid dead ends. Ideally, the locker room should have a wet side where showers and toilets are located and a dry side for lockers and circulation.

This wet-side and dry-side layout also applies to how air is distributed in locker rooms to maintain a positive airflow. Dry-treated air should be supplied to the dry-side activity (i.e., locker area) and returned over the wet side (i.e., shower and toilets). Pool deck access to toilets should be convenient.

Family-changing rooms should be included to provide enhanced privacy for families or anyone who needs additional privacy. The current design trend requires more family-changing suites. Provide at least one family-changing suite with a larger area to accommodate a changing bed for those requiring assistance. If possible, provide at least two accessibility entries to the pool using handicapped lifts or handicapped ramp access.

TEAMWORK

Lastly, teamwork is the key to achieving optimum aquatics center design for your unique needs. Once you have determined the program requirements for your proposed facility, it is time to engage an architecture and engineering team with proven experience in the design and construction of aquatic centers. Working together as a team, you will be able to identify, evaluate, and optimize the many decisions required according to their cost, sustainability, and design objectives.