These conditions are uncomfortable for guests and create damaging condensation.

At the same time, indoor air quality is becoming an increasing concern for patrons. Chloramine-laden air is uninviting at best. Some studies suggest the poor air quality that results, in part, from improper ventilation may be linked to asthma and other respiratory ailments.

That’s why selecting the proper heating, ventilation and air conditioning (HVAC) system for your indoor waterpark facility is essential. With so many different options available, choosing the right one for you can be difficult.

Here’s an overview of the five basic types of dehumidification technologies currently available, including estimated cost per square foot and relative operating costs for each technology. Because technologies and system designs can vary, mechanical and electrical installation costs cannot be easily factored into the following examples.

1 Heating and ventilation system. This is the most basic of dehumidification systems. Moisture removal is accomplished by diluting indoor air with less humid outside air.

This brute force approach to dehumidification was developed under the premise that pumping in enough drier outside air can offset the effects of pool evaporation.

H/V systems require the lowest initial capital expenditure, but they have no practical means of cooling the air during hot summer months, especially when the temperature difference between outside and inside is minimal. Temperature and humidity control are generally around a plus or minus 30 percent variation in the summer.

During cold winter months, H/V systems must raise the inside diluted air temperature from the outside ambient to 85 degrees Fahrenheit (the desired temperature for most indoor waterparks). With typical winter temperatures hovering around freezing, operational costs can be quite high.

The estimated first cost for a 30,000-square-foot facility is $15 to $18 per square foot.

2 H/V system with heat recovery. The addition of a heat-recovery device may reduce operating costs for an HVAC system significantly.

In these systems, heat is recovered from the exhausted air and used to condition the incoming air. The drawback is that while energy recovery is high, latent water vapor heat is not always removed from the exhausted air. This latent heat can comprise up to 50 percent of the energy in the exhausted air.

Another disadvantage is that a heat-recovery device can boost initial capital costs on the HVAC system 25 percent to 30 percent more than a basic H/V system. The heat-recovery device is only beneficial in winter. Summer temperatures and humidity control are poor, with as much as plus or minus 30 percent fluctuation.

The estimated first cost for a 30,000 square foot facility is $19 to $20 per square foot.

3 Heating and ventilation system with heat recovery and cooling coil. Adding a chilled water-type cooling coil to a basic H/V unit provides all-season temperature control.

In this type of HVAC system, dilution with outside air is still the primary method of wintertime moisture control, and the cooling coil can provide partial or full dehumidification as well as summertime space cooling. This enables greater comfort during the all-important summer season, and more accurate temperature and humidity control with plus or minus 5 percent variation from desired set points.

This system is only practical if chilled water is available from an independent source such as the building’s main HVAC system. The tradeoff is that operating a cooling coil requires more energy consumption at the chilled water cooling plant, making the operating cost higher than the previous two versions.

The estimated first cost for a 30,000-square-foot facility is $20 to $21 per square foot.

4 Heating and ventilation system with heat recovery and cooling coil with hot gas reheat. In a conventional air conditioning system, the heat extracted from the air and the heat of compression are discharged to the outside by means of a condenser coil and fan unit.

By diverting the waste heat to a hot gas reheat coil in the supply air stream, the energy is recovered and reintroduced to provide supplemental space heating.

As expected, the capital cost for this type of HVAC system is higher than previously described options because of the added components, but operational costs are lower when compared with a system lacking the reheat option.

In addition, hot gas reheat may be practical only on DX systems where the compressor is part of the packaged unit. The hot gas reheat approach offers energy recovery and very precise air temperature and humidity control during all seasons for occupant comfort.

The estimated first cost for a 30,000-square-foot facility is $21 to $22 per square foot.

5 Heating and ventilation system with heat recovery, cooling coil with hot gas reheat and pool water condenser options. The final HVAC system is the most comprehensive dehumidification option. Waste heat can be directed to either warm the space or the water. In this case, an additional heat exchanger (pool water condenser) can provide the bulk of the water heating.

While the initial expense for this type of system is the greatest, operating costs are at the lowest because all available energy sources are utilized, thus limiting the reliance of fossil fuels to maintain occupant comfort.

Plus, this type of HVAC system can utilize features of the less expensive units as an economizer mode that provides cooling without use of the compressors.

The estimated first cost for a 30,000-square-foot facility is $23 to $24 per square foot.