Ventilation of Public Swimming Pools.

Ventilation codes for swimming pools are based on preventing condensation. To save energy, air recycle with dehumidification is common. This successfully controls moisttke, but does not remove airborne contaminants arising from evaporation of chemically treated pool water. This contamination may cause discomfort, irritation or even harm. Environmental conditions and energy consumption were monitored at two public swimming pools over one year to identify the critical factors affecting bather comfort, to relate these to proportions of recycled air, and to show how to achieve acceptable bather comfort while minimising energy costs. Questionnaire surveys showed that even under the most comfortable conditions, 20 to 30% of pool users suffered irritation, mainly of the eyes, attributed both to the air and to the pool water. Over the range of fresh air conditions available using the existing plant, discomfort experienced by pool users was not found to relate to the ventilation conditions, but rather to the level of chlorine compounds ("combined chlorine") in the water. High combined chlorine levels in the water are expected to result in high levels of contamination in the air, but this proved difficult to measure. However, increasing the fresh air ventilation rate when the combined chlorine level in the water is high is desirable in order to dilute airborne contaminants, and it is proposed that the combined chlorine level in the water should be used as a fresh air ventilation control parameter, along with humidity and carbon dioxide, to minimise energy use and maintain acceptable air quality.