At indoor waterpark resorts, swimming is no longer an activity relegated to the summer.
However, maintaining a constant pool environment requires
year-round attention, especially as outside and inside variables
change season to season.
It’s a given that outside temperatures directly affect the
inside heat loss/gain. For a majority of indoor pools, water and
space heating are required 70 percent to 90 percent of the year, so
when weather turns cold, it’s critical to carefully manage
the humidity, and air and water temperatures in the pool
environment to avoid escalating energy costs.
The key is to maintain summer-like conditions on the inside
regardless of the weather outside. By adequately monitoring and
maintaining humidity, you can do that cost-effectively.
For starters, ideal water temperature is around 82 degrees
Fahrenheit, with the air temperature slightly higher. To maintain
those optimal set points, controlling humidity is essential. The
desirable humidity range is generally 50 percent to 60 percent.
Humidity greater than 60 percent creates a sticky feeling and/or
difficult breathing. Low humidity results in evaporative cooling on
the bather’s skin, causing a chill.
During winter months, the moisture content of the outside air is
generally lower, making it suitable for dehumidification. However,
the outside air temperature is much colder and requires constant
heating to maintain comfort within the facility. If left unchecked,
the heated air will be constantly exhausted while the incoming air
will have to be heated, escalating operational costs. That’s
where efficient dehumidification equipment comes in.
Dehumidification systems utilizing refrigeration are considered
some of the most precise in terms of overall control of
dehumidification and temperature. The technology uses electricity
as the primary energy source and offers a reclaim mechanism in the
form of a heat pump cycle, which adds the heat back into the air
Mechanical dehumidifiers recover more of the latent heat from
pool water evaporation than passive heat exchangers. They also have
sophisticated control systems that can constantly monitor inside
and outside temperatures and humidity settings, choosing the least
costly method to control the set point conditions.
Some operators have outside-air-based dehumidification
equipment. These packaged dehumidification units use ventilation to
remove moisture, and feature sophisticated mechanics and software
to minimize operational costs. To be practical for winter
operation, OA systems should be equipped with heat exchangers
within the exhaust circuits. Cost savings can be significant, with
improvements up to 50 percent compared with units lacking heat
No matter what kind of system you have, here are a few
additional strategies for wintertime operation that can help lower
- Reduce the ventilation rate during off-peak
hours. Humidity set points generally are established to
maintain desirable levels during peak operational times, when the
rate of evaporation is high. Lowering the amount of ventilation to
meet the lower evaporation rate during off-peak hours reduces fan
operation, as well as the heating requirements. Savings generally
are significant (up to 50 percent) compared with constant operation
day and night.
- Install temperature sensors. Monitoring
temperatures of exterior walls, windows and roofing can save energy
and prevent damaging condensation. Mount cold-temperature sensors
on the coldest surfaces. When connected to the HVAC control system,
they check the surface temperature, and systems can automatically
lower the dew point when required.
- Don’t deactivate your dehumidification
system during off-hours. It’s not uncommon for the
space temperature to drop 10 to 15 degrees at night during colder
seasons. This greatly increases the rate of evaporation due to the
large difference in vapor pressure. With air distribution systems
off, moisture rapidly rises vertically to the cold ceiling,
condenses and drops back into the pool, resulting in cosmetic and
structural damage. Instead, dehumidify at the minimum level and
maintain proper air temperatures to minimize evaporation.
- Use a thermal blanket or cover on unoccupied
pool surfaces. This is perhaps the simplest energy-saving
strategy. Covers eliminate water-to-air interaction by providing an
impermeable membrane over pool surfaces. With covers in place, a
temperature setback can be implemented during off- hours, saving
energy on space heating.
- Manage pool water agitation. Another
factor when managing water evaporation is water agitation. It
creates more surface area, resulting in increased evaporation.
Agitation can be as simple as swimmers splashing or spray from
Careful management of peak-load dehumidification along with
shutting off unused waterfeatures can help eliminate unnecessary
pool water agitation. Also avoid the use of absorbent deck
coverings such as carpet, and limit wet deck areas by installing
adequate drainage and/or reducing deck overspray.