How to avoid humidity problems with indoor swimming pools

Building an indoor swimming pool is often a large investment, and it is important to protect the pool building correctly from mould, rot and corrosion by installing the appropriate dehumidification system.

Dehumidification is crucial in swimming pool buildings

It happens while you are splashing around in the pool, increasing the surface of the water and causing water to hit the tiles around the pool. Even when you are lying on your lounger watching the still surface there is no way to avoid evaporation. In fact, several thousand litres of water can evaporate from a large swimming pool in a single day. If not dealt with in the right manner, this evaporation is surely going to cause problems.

Far too many private and public indoor swimming pools have been destroyed because the inventory, walls and building structures were eaten away by mould, rot, and corrosion – all because an adequate dehumidifying system was never installed.

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Chlorine is aggressive

Humidity in itself is critical, and at the same time chlorine added to the water is an aggressive substance, which severely attacks building materials when present in condensation.

This is why appropriate dehumidification is crucial in swimming pool buildings. In addition to protecting the building, dehumidification is also about people’s comfort. Excessive humidity will cause a bad indoor environment and lead to visitors and staff having a bad experience at the pool.

Swimming Competition

Understand the air

To understand the processes of evaporation and dehumidification, you need to think of the air as a mixture of dry air and water vapour. We call this mixture humid air.

Air expands when it is warmed and contracts when it is cooled. When air is warmed up it will hold more water vapour, and when it cools down it holds less water vapour. When the air cools down significantly it reaches the dew point, meaning that the air saturates and the water vapour condenses as water.

The dew point is a crucial term in relation to the dehumidification of indoor swimming pools. Humid air will condense on a cold surface when the temperature of the cold surface is below the dew point.

The highest relative humidity allowed with any given room temperature is defined by:

  • The insulation grade of the building
  • The water content of the air
  • The outdoor air temperature
  • The air circulation in the room

For example, if the air inside a swimming pool is at 28 °C and it has a relative humidity of 60 %, the air will condense on the wall if the wall’s temperature is less than 19.5 °C.

Swimming Pool with Dantherm CDP dehumidifier

The ultimate guide to dehumidification

If you want to learn more on dehumidifying swimming pools, we encourage you to sign up to download our whitepaper “Selection Guide - Dehumidification of Swimming Pools”.

The objective of this guide is to provide a tool for choosing the correct pool dehumidifier – regardless of whether it is for smaller pools, hotel swimming pools, or public swimming pools.

A good dehumidification solution is an overall solution, and this guide relates to both dehumidification, temperature regulation, and ventilation.
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Dantherm is a market leading supplier of energy efficient climate control solutions for customers across the globe. Ask your pool supplier for a Dantherm product.