Control strategies make the difference
Dehumidification equipment manufacturers have made great strides in improving operation by using high-efficiency components. When combined with a sophisticated control system, however, additional advantages can be earned.
Occupied/unoccupied mode
Although commercial swimming pools are rarely occupied 24 hours a day, dehumidification is still required to maintain indoor air quality. At the same time, however, ventilation requirements are not necessary. If the equipment’s control system includes an ‘occupied/unoccupied’ mode, the pool’s outside and exhaust air fans can be turned off to further reduce energy costs.
Condensate prevention system
To the untrained eye, condensation formation may seem more like an esthetic problem for an aquatic facility; in fact, it can lead to structural component deterioration and inefficient use of energy and equipment. A wall condensate prevention system, however, will constantly monitor outdoor climate conditions via a sensor on the coldest inside wall. As the outside temperature lowers (along with the wall temperature), a smart control system will lower the space dew point as needed. This prevents condensation on the cold surface, unnecessary over-sizing of the dehumidifier and excessive compressor operation.
Economizer operation
Depending on the facility’s geographic location and the low percentage of times cooling is required, waste heat removal is still necessary. By utilizing an indoor pool’s huge thermal mass (ability to store heat), a well-engineered dehumidification system can redirect waste heat to the pool with little affect on water temperature, thus eliminating the need for an external condenser. Energy savings are achieved by minimizing compressor and eliminating condenser motor operation, which in turn reduces impact on resources.
In addition to traditional economizer operation, a variation called the ‘smart economizer’ supplements water and space heating using outside air. As hot, moist air travels over the evaporation coil to cool and dehumidify, the smart control system compares it to outside conditions. If the outside air is warmer and dryer than the conditioned air, it is used and the conditioned air is exhausted. This system will add another 15 to 20 per cent in energy savings over dehumidifiers without an economizer.
Passive air-side heat recovery system
Ventilation is mandated in all commercial buildings, and indoor pools are no exception. However, ventilation becomes more costly in colder climates where make-up air must be heated to maintain desired space conditions. By installing a passive, air-side heat recovery system, heat energy that is normally exhausted during space ventilation can be captured to preheat incoming air, thus saving considerably on fossil fuel requirements.
Carbon dioxide (CO2) demand-based ventilation
Another way to reduce ventilation requirements, especially during swim meets or limited occupancy, is through CO2 demand-based ventilation. Many dehumidification systems have a preset ventilation volume based on average occupancy. Controllers equipped to monitor CO2 levels, however, can adjust ventilation needs to meet the occupancy requirements while not over ventilating. By reducing heating and cooling loads, overall operating costs can be reduced quite significantly.
‘Smart’ pool water pump control
The same theory applies to the dehumidification unit’s pool water pumping system, which is separate from the pool’s circulation system. Most dehumidification systems are designed to heat either the air or water using energy recovered through the dehumidification process. By using a ‘smart’ pool water pump control as part of the control system, the unit’s pump is turned off when the system is in air priority mode. Using this device as little as 50 per cent of the time can save a facility up to $3,000 per year.
