July 2016 - Parks & Recreation - 66

Operations

Regulating Air Quality for Indoor Pools
By Dennis Berkshire

he old days of walking into a sports and recreation facility and being hit with
the strong smell that indicates the presence of a swimming pool are long
gone. As the aquatics industry has grown so has the public's expectation of a
healthy, safe and inviting environment for indoor public swimming. Modern
natatoriums (indoor swimming pools) are designed to ensure health and comfort for
bathers, spectators, facility staff and the protection of the building and components. The
most difficult of these conditions to regulate is the air quality.
Recipe for Good Air Quality
The recipe for good air quality is a result
of facility and system design, operations
and programs in this space. The proper
control of water and air temperatures, air
relative humidity, air ventilation and pool
water chemistry balance will all contribute to the air quality in the natatorium.

Humidity and Air Temperature
Patrons are typically more sensitive to humidity than they are air temperature, so
trying to achieve a balance of the relative
humidity and the natatorium air temperature can be key. To minimize the amount
of water evaporation and overall loads to
humidity, maintaining air temperatures
1-2 degrees warmer than the pool water
temperature is ideal. When the water
temperature goes up for pools, such as for
instructional and therapeutic pools, the

higher air temperature is not practical for
bather comfort. The table contained herein gives examples of the conditions for
typical types of swimming pools.
Air Velocity
Air movement across the pool water
surface is another air quality factor. For
bather comfort, it's best to minimize air
movement and any drafts at pool water
level. However, for the elimination of
chloramine fumes (the chlorine smell
in air), greater air movement across the
pool water allows chemical off-gassing,
preventing foul-smelling air. The greater
the air movement across the pool water,
however, the higher the water evaporation rate. In general, try to have a maximum air velocity of 20-30 feet per minute to achieve off-gassing and minimize
evaporation.

Conditions for Typical Types of Swimming Pools
Type of Pool

Air Temp ⁰F

Relative
Humidity %

Water Temp ⁰F

Competition

75 to 85

50 to 60

78 to 80

Recreation

80 to 85

50 to 60

82 to 86

Wading

78 to 85

50 to 60

84 to 90

Instructional

80 to 85

50 to 60

84 to 90

Therapy

80 to 85

50 to 60

86 to 94

Spa

80 to 85

50 to 60

100 to 104

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In addition to balancing air quality,
the rates of off-gassing and evaporation
must also be balanced with operating
costs. For example, an increase in water temperature from 82 degrees to 84
degrees, will see an almost 10 percent
increase in the HVAC energy costs.
Conversely, reducing the HVAC system
from six to four air changes per hour
will see an almost 20 percent reduction
in HVAC energy costs.
The most important aspect of the
HVAC system to air quality is the ability to remove the air with the most contaminants from the natatorium. This air
is heavier and, therefore, typically is located directly above the pool water. The
location of both the supply air and return
air HVAC openings to allow this removal to occur can reap huge benefits in air
quality. For existing facilities that cannot adjust supply and return openings,
large-volume, low-speed, overhead fans
can be very helpful.
Water Chemistry
Water chemistry balance is the final ingredient in this recipe for good air quality. Maintaining constant break point
chlorine levels and/or the use of ultra
violet supplemental disinfection to prevent or minimize chloramine formation
can contribute greatly to the water and
air quality.
The right design and operation of your
sports and recreation facility will help everyone to breathe a little easier.
For detailed references to air quality standards discussed in this article, go to www.
parksandrecreation.org/2016/July/Regulating-Air-Quality-for-Indoor-Pools.
Dennis Berkshire is President of the Aquatic Design
Group (dberkshire@aquaticdesigngroup.com).

July 2016 - Parks & Recreation

Table of Contents for the Digital Edition of July 2016 - Parks & Recreation