Natatorium Design For Beginners

Creating a comfortable space for swimmers and spectators

By Justin Caron

At their best, they create one of the most exciting atmospheres in sports; at their worst, they leave your eyes bloodshot, throat sore and clothes reeking of chemicals. Unfortunately, when most people think of natatoriums, they all too often remember the poorly designed facilities, and don’t recall those that were well-designed.

The environment inside a natatorium is similar to that of an equatorial jungle with chemical fumes instead of giant insects. In this setting, improper training of operations and maintenance staff can lead to a situation where it is obvious that a pool is somewhere within the building--you can smell it before you actually see it. However, this “smelly swimming-pool syndrome” cannot always be attributed to poor maintenance--many common problems stem from improper design.

There are three major issues that should be taken into consideration during the design phase in order to create a natatorium space that is easy to operate, flexible for a variety of programs, highly sustainable and comfortable for swimmers as well as spectators.  These include:

·         Air quality

·         Pool-deck layout

·         Building layout.

Air Quality

Air quality is perhaps the most important factor that can affect the experience of swimmers, spectators and staff members. Despite this fact, designing for improved air quality is often the area in which corners are cut when money gets tight.  

The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) recommends a minimum of six air changes per hour (one turnover of the equivalent amount of air in a building) for a natatorium.  For spectator areas within the natatorium, ASHRAE recommends increasing the air-flow rate to eight turnovers per hour. This is because humans experience much higher discomfort with rises in humidity than they do with rises in temperature (think New Orleans on a sticky, 80-degree day versus Phoenix on a dry, 90-degree day). Air changes within a natatorium are absolutely critical--bringing fresh air into the space helps to flush out impurities, and (depending on geographic location) also can reduce humidity.

Another contributing factor to poor air quality is that many heating, ventilation and air-conditioning (HVAC) systems for natatoriums are designed for typical buildings, with both supply (conditioned air coming into the space) and return (air leaving the space) air ducts installed at the ceiling level, which is often 20 feet or higher above the water surface level. Chemical reactions between chlorine and organic contaminants within the pool result in off-gassing of chloramines, which are heavier than air. Typical building HVAC duct arrangements do not work well since warm, humid air rises within the space, adversely affecting air quality for spectators, while the chloramines stay close to the water surface level, making life somewhat less than pleasant for swimmers. This problem can be mitigated by designing the facility so that the return air ducts are as close as possible to the pool water surface, and the supply air ducts are located at ceiling level.

Technology has significantly improved over the last decade, which has enabled many aging facilities to drastically improve air quality. Charles Logan, director of one of the most highly regarded natatoriums in the country--the Lee and Joe Jamail Texas Swim Center at the University of Texas in Austin--discussed Phase I of a recent renovation that included the addition of a UV system as well as new controllers to monitor and better control the water chemistry. “Before [the renovation] the chloramines were terrible when we would host meets. We recently hosted our first meet since the modernization, and there was virtually no sign of chloramines in the facility.”

Here are key design considerations for enhanced air quality:

·         Meet (or exceed) ASHRAE standards for air turnovers within the natatorium.

·         Locate return air ducts as close to pool water surface as possible; locate supply air ducts at ceiling level, and allow supply air to “wash” building perimeter walls, particularly walls with glazing.

·         Maintain air temperature within 2 degrees Fahrenheit (preferably higher) of pool water temperature to reduce potential for a build-up of condensation on natatorium walls and finishes, and provide swimmer comfort.

·         Maintain relative humidity between 50 and 60 percent within the natatorium.

·         Maintain proper oxidant residual (chlorine, bromine, etc.) within pool water to stay ahead of peak bather loads; many air-quality problems are actually water-chemistry problems, and can be addressed by this.

·         Supplement pool chemicals with ozone and ultraviolet (UV) sterilization systems, which can significantly reduce the chloramines that are the cause of most eye and throat irritation.

·         Use thermal blankets (commonly known as pool covers) to reduce operating costs for heating pool water, and improve air quality by reducing evaporative water loss.

·         Use heat-recovery ventilation systems in extreme climates to significantly reduce heating and cooling costs.

Pool-Deck Layout

Adequate deck space around the pool(s) is another factor that is often a victim of cost-cutting measures during design. Many state health codes require a minimal amount of unobstructed deck space surrounding swimming pools.  This number can range from as low as 4 feet to as high as 10 feet as measured from the pool edge, depending on jurisdiction. The Americans with Disabilities Act (ADA) requires a minimum of 6 feet of unobstructed pool deck space for wheelchair/disabled access. These minimal requirements are often treated as if they appeared in the Declaration of Independence due to the high costs associated with natatoriums--unlike outdoor pools, for every square foot of pool or pool deck there is a very expensive square foot of natatorium overhead.

Pool-deck layout, design and size vary greatly depending on the programmatic uses within the natatorium. A lap pool within a local fitness center can likely get by with the minimal decks noted above. Therapy pools need more deck space to accommodate ramps and access lifts, which provide less-mobile patrons access to and egress from the pool. Teaching pools need at least one area of ample deck space (15 feet or more) for dry land instruction and tighter deck space in other areas to limit where children can roam. Recreational pools--due to the large number of people and the excited state of patrons--need large, spacious decks of at least 20 feet in all directions. Competitive venues also require ample deck space during competitions, since many athletes, coaches and officials will be on deck. During practice, the decks double as dry land areas for activities as such as stretching, isometric exercise and instruction. Decks for competitive pools normally will be at least 10 feet on each side (preferably 15 feet), with at least one area of at least 20 feet to accommodate overflow, meet-management and temporary bleachers.

Key design considerations for a pool-deck layout:

·         Adequate deck space should be dictated by programmatic use, and not compromised as a result of cost considerations. The phrase, “I wish we didn’t have this much deck,” is rarely heard in natatoriums--if you can possibly afford it, err on the side of more pool deck.

·         Relevant codes and common sense dictate that there should be no standing water on pool decks. Good deck drainage systems will ensure that pool decks last a long time, and reduce slip/fall injuries.  

·         Commonly used pool-deck surfacing solutions include broom-finish concrete and unglazed ceramic tile.  Pool-deck surfaces should be non-slip to mitigate accidental falls, as well as non-porous to prevent bacteria/algae growth and reduce maintenance.

·         ADA regulations mandate that pool-deck slopes should be no greater than 2 percent and not less than 1 percent.

Building Layout

The layout of the building and surrounding spaces is also very important when designing a natatorium. The natatorium is likely the largest space in the overall building envelope, and is the best suited to use natural light. Depending on location, direct access to outdoor green-space for overflow and related activities during competitions and camps is also desirable. Most natatorium spaces are located at the perimeter of buildings. Locker rooms should open directly into the natatorium to prevent patrons from traipsing water between the pool and the locker rooms. Locker rooms also should open directly to dry areas to prevent patrons from tracking dirt and other debris into the pool area. Whenever possible, there should be a central lifeguard area and an area that can serve as a meet-management area during competitions, with a full view of the pool(s). This will help safety and prolong the life of equipment used during swim meets. Storage is always at a premium in natatoriums and should be included during the planning process.

Key design considerations for a building layout:

·         Natatorium spaces should be positioned to take advantage of natural lighting, but windows should be oriented to reduce glare on the water surface, typically on north building walls or in a clerestory (high on building wall) configuration.

·         All means of access to the natatorium should be designed to keep dry users in dry areas and wet users in wet ones--shoes on pool decks bring contaminants and debris, and wet feet in dry areas make for slippery floors.

·         Special attention should be paid to ensure that all entrances and exits are ADA-compliant.

·         In addition to locker rooms that serve pool patrons, there should be at least one family locker room that can accommodate parents with younger children, and transgendered patrons--both groups that aren’t comfortable in traditional changing areas.

Finally, one should acknowledge that no matter how well a facility is designed, special care must be taken to ensure that it is properly maintained. Logan feels that proper training and diligent maintenance will not only improve the perception of a venue, but also increase its lifespan. He says, “When visitors come to see the facility, they should not be able to tell whether the facility is 5 years old or 30 years old.” With proper design--including special attention to air quality, pool-deck layout, and building layout, as well as proper training and upkeep by a team of dedicated professionals--any natatorium can be a place where swimmers, spectators and staff can focus on the attractiveness of the facility and the aquatic activities, rather than asking themselves why they are in this smelly, crowded and unpleasant place.

Justin Caron, a former NCAA Division 1 competitive swimmer, is an Associate with Aquatic Design Group, a Carlsbad, Calif.-based architecture and engineering firm, specializing in the design of competitive, recreational and leisure-based aquatic facilities. He can be reached via e-mail at jcaron@aquaticdesigngroup.com.