Pool evaporation is inevitable… and evaporation costs in so many ways.
An indoor swimming pool continuously produces large quantities of chlorine or salt-laden water vapour through the process of pool water evaporation. This can rot a building from the inside out and can also affect indoor air quality.
When humidity goes to high and a building has cold surfaces or air leaks to outside it causes numerous problems. The moisture from the pool coming into contact with cold surfaces produces rust, blistering of paint, deterioration of structural supports and many other negative cosmetic effects on your building. Repair or replacement of damaged items is very costly and difficult to get right.
Patrons and staff of indoor pools must endure an unpleasant environment and they are affected by the physical discomfort of high humidity. The mould, mildew, bacteria and fungi that can grow in these moist conditions may affect their health. These growths give off
low-molecular-weight volatile organic compounds (VOCs). Many VOCs are poisonous and introduce odour.
Indoor swimming pools continuously produce large quantities of chlorine laden water vapour through the process of water evaporation. The effects of this evaporation are magnified by the fact that the construction industry keeps building poorly insulated buildings and leaky buildings which can be very draughty. high humidity and poorly insulated surfaces in the building envelope can cause numerous problems:
- blistering of paint,
- deterioration of structural supports
- and many other negative cosmetic effects
on your building.
Naturally, most people may think that in order to fix these problems, you need to ventilate the space more, but in actual fact, the opposite is more effective.
There are 2 ways to deal with swimming pool high humidity.
- Remove the moisture from the air
- Reduce the moisture from being emitted in the air.
By using an Energy Recovery Ventilator (ERV), humidity and discomfort can be reduced. The added bonus of the ERV compared to conventional dehumidification is that fresh air is constantly being brought into the building. This sort of a system on its own can also exacerbate the problem by introducing more air flows on top of the water which can inadvertently raise humidity.
The more efficient solution is to constantly pressurise a well constructed relatively airtight building, which in turn creates a layer of still air on top of the water, which inturn reduces evaporation in the first place. By creating a layer of still air on top of the water, it’s like a mechanically induced layer of insulation on all surfaces including the water. This process significantly reduces evaporation of the water, which in turn significantly reduces humidity without the need for dehumidification.
Combining a positive pressure system with Air tightness, in conjunction with an ERV is the ultimate solution.
- highly insulated ceilings, walls and floors (no cold spots), especially parapets
- NO SINGLE GLASS, especially between wet and dry zones – Use only double-glazed windows and thermally insulated frames (no metal frames unless thermally broken)
- An Airtight building envelope. Target 2-3 m3/h/m2@50Pa, because it is really important for building longevity and occupant health! But in order to achieve this level of air tightness, it doesn’t happen by chance and the designer and builder need to work extremely closely to iron out all junctions throughout the building envelope. Otherwise, it is unreasonable to expect a builder to be able to achieve a target leakage rate of under 5m3/h/m2@50Pa.
- Integrate ERV/HRV to bathroom/shower ventilation services.
2. Wet Area finishing: e.g. blue-board or cement sheet walls and ceilings, corrosive-resistant finishes, etc… The Airtightness layer should be vapour impermeable, and the insulation layer should be continuous on this layer.
3. Insulation should be continuous, on walls connected to outside, as well as on walls connected to dry zone areas.
4. Doors to outside or dry areas should never be pinned open. Otherwise, pressure cannot be maintained. The other issues are, that doorways are usually located down low, and air flows down low, on top of the water can increase humidification.
5. Heat the air as well as the water (e.g. 26C water & 24C air).
6. Ventilate Sustainably with an Energy Recovery Ventilation & Air Filtration System:
- low energy use
- removes moist indoor air and corrosives (chlorine gas and salts),
- recovers up to 80% of heat from pool room and uses this to pre-heat incoming fresh air,
- and returns condensate to the pool.
7. Use a Pool Blanket when the pool is not in use (reduces evaporation by 30%).
8. Surface-mounted lighting – to prevent any ‘break’ in wall or ceiling (moisture can penetrate and/or insulation coverage may be compromised). The air barrier must be in line and continuous with the thermal insulation layer.
9. Monitor conditions – indoor and outdoor air temperature, indoor humidity and water temperature.
10. Pressure test your building on a regular basis, to ensure, your aquatic centre is performing.
How You Can Save
- Blower door testing/ Whole building air tightness testing
- Remdiation works, that last the test of time
- Reporting on where issues are so that you can get other companies to remediate.
Building performance is king, get that right, and its amazing the things that you can do.