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A strong “chlorine” odor is an indicator of poor pool water chemistry and is generally offensive to the occupants. Higher
levels of chloramines can cause skin/eye irritation and respiratory problems commonly known as “lifeguard lung”.
Most poolrooms are designed with a minimum ventilation rate to dilute the airborne pollutants generated from the
chemical interactions in the pool water. Typically these rates are based on ASHRAE standard 62.1 and dictated by local
codes at about 0.5 CFM/square foot of pool and deck area, but depending on the pool water chemistry the ventilation rate
may not always be adequate for good poolroom IAQ.
However, increasing ventilation rates can significantly add to the cost of operation. Energy conservation strategies such
as heat recovery, airflow measurement and CO2 based control help control costs while improving IAQ.
Depending on the geographic location and season of the year, treating the outside air has a direct effect on energy
consumption. Some facilities prefer higher than minimum ventilation rates, up to 100% of OA, to maximize indoor air
quality, but the cost of treating this air can be significant.
OCCUPANT COMFORT
Occupant comfort in a natatorium is easy to understand. If you ever swam in an outdoor pool on a cold, windy day
or exited a pool in a dry, desert location you will probably notice an immediate chill. The opposite is true where high
humidity is not adequately controlled either through ventilation or by mechanical means. The moisture level can
reach such a state where it is oppressive or stuffy. Common complaints are difficulty in breathing and the room being
perceived to be warmer than the actual dry bulb temperature would suggest.
Regardless of the source of discomfort, users will not enjoy the facility if water/air temperatures and humidity levels
are not within a narrow range. Ideal water temperature is around 82°F with the air temperature about 2˚F higher to
prevent chilling when exiting the pool and to minimize evaporation from the pool surface. Refer to Table 1 for some
recommended temperatures for poolrooms, which can be adjusted to meet specific needs of bathers. In general, “active”
poolrooms are maintained at lower temperature ranges so the users don’t overheat, while warmer temperatures are more
common for seniors or children or less active pools.
The desirable humidity range is generally between 50 and 60%. A humidity level greater than 60% can create a sticky
feeling and difficulty breathing. A humidity level lower than 50% will result in evaporative cooling on the bather’s skin,
creating a chill. Poor air movement caused by improper duct placement within the poolroom will also lead to occupant
discomfort. Excessive supply air blowing on bathers can create drafts, while uneven air distribution may create stagnant
zones within the space.
Table 1-1. Typical Pool Water and Air Temperature Set-Points
Water Temp.
o
F
Air Temp.
o
F
Room RH %
Recreational Pools
80-85
Water Temp + 2
55-60
Therapy Pools
86-92
86
1
55-60
Whirlpools
99-104
86
1
55-60
1
Normally max 86
o
F to minimize overheating of occupants
POOL WATER CHEMISTRY
Water chemistry in swimming pools is critical for the health of the bathers and the condition of the enclosure and
components. An enclosure with poor water chemistry has a noticeable “chlorine” smell, which is an indication of high
chloramines in the air. Not only does this have an effect on the water, but it affects the bathers and the air they breathe.
Dehumidification/ventilation equipment is not designed to remedy the effects of poor pool chemistry, but is designed to
deliver prescribed ventilation to manage smaller amounts of pollutants generated from normal pool activity. Pool water
chemistry is a part of daily maintenance and it is recommended that the users follow the current National Spa and Pool
“Indoor Pool Water Chemistry – Controlling Chloramines with Proper Chlorine Management,”
, for more information on pool water chemistry.
