Gas-phase air purification
Another common natatorium concern is the accumulation of chloramines, which are inorganic compounds that produce strong odours and can cause skin, eye and respiratory issues among bathers. Some aquatic facility operators attempt to remedy this problem by inefficiently exceeding the outdoor air levels recommended by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).
An example of a better way to handle this issue can be found at the Nottawasaga Inn Resort, in Alliston, Ont., where chloramines built up on days with high bather loads (Pool & Spa Marketing, October 2009). During the replacement of the facility’s 20-year-old dehumidifier, the owners originally considered introducing more outdoor air, which would decrease energy efficiency and require expensive ductwork additions. Instead, operators chose a gas-phase air purification filter option for the dehumidifier, which serves as a good second line of defence against pool area odours.
In a gas-phase filter, room air is drawn through a sorptive/reactive filter material that removes gaseous contaminants such as chloramines, which pass freely through other filters. The filter media can be tested periodically for efficacy and is easily replaced when necessary.
Heat recovery coils
By code, commercial natatoriums are required to bring in a certain amount of outdoor air to maintain healthy IAQ levels. Consequently, air must be exhausted to allow space for incoming air; in a natatorium environment, exhausting 27 to 30 C (80 to 86 F) air is wasteful. However, recent heat-recovery coil innovations allow for the transfer of both sensible and latent heat from the exhaust air to the incoming outdoor air. For example, on a cool Canadian day with an outdoor temperature of –12 C (10 F), outdoor air can be preheated by about 30 C before using expensive purchased energy to heat the facility to the desired 27 to 30 C range. This method can save more than C$6,000 in annual energy costs in an average-sized community centre pool.
The amount of outdoor air introduced to a facility can also be controlled by carbon dioxide (CO2) and/or air flow monitoring. For infrequent large crowds, such as those assembling at a swim meet, more outdoor air should be used to rid the space of CO2 accumulations associated with human exhalation. However, bringing in the same amounts of outdoor air during idle or limited use periods is wasteful. Therefore, CO2 monitors can determine the amount of outdoor air required to maintain healthy IAQ levels.
Economizers
Another energy-efficiency choice that relates to outdoor air is whether to use an economizer. This device inhibits refrigeration and introduces 100 per cent outdoor air to an aquatic facility when outdoor ambient conditions are suitable for dehumidification and/or cooling. Use of this device is an economic consideration, since the decrease in space cooling and dehumidification costs must be compared to increases in heating costs. However, for certain projects, economizers can produce a quick payback.
Econo-purges are a variation on the economizer. Dehumidifier purge mode is popular for evacuating indoor air in 10 minutes during super-chlorination periods, when chemical odours can become overwhelming. Besides purging, this feature also makes an excellent economizer when incorporated into the dehumidifier, with an even better payback than normal economizers.
Blowers and motors
New technology in blowers and motors can also save energy and deliver short paybacks. Direct-drive blowers save energy compared to belt-drive blowers. Induction motors can easily be equipped with variable-speed drives, which can reduce energy usage when airflow demands increase. Energy-saving, electronically commutated (EC) motors can also be retrofitted into existing dehumidifiers. Both direct-drive blowers and EC motors offer both energy and maintenance savings.
Refrigerants
An existing dehumidifier manufactured before 2005 is probably using R-22, which was declared to be an ozone-depleting refrigerant along with other hydrochlorofluorocarbons (HCFCs) and chlorofluorocarbons (CFCs) under the Montreal Protocol. Manufacturing of new equipment using R-22 ended on Dec. 31, 2009. Refrigerants allowed under the Montreal Protocol, such as R-407C and R-410A are available for new units.
