Ventilation of Indoor Pools and Spas
Natural ventilation is an aspect that needs to be considered in the initial stages of a wet area in the design of a building and not afterwards when you suddenly scramble about trying to find a quick & easy solution, because there isn’t one.
Before the selection and implementation of natural ventilation equipment to wet area enclosures an understanding of the dynamics involved is required.
An indoor pool/spa area is not just a larger bathroom as the presence of a large heated water volume is constant, not occasional.
It is not that mechanical services should not be employed in establishing the correct ventilation necessary, but more that they should be a refinement to the theme and not the theme itself.
Mechanical services are also subject to failure in a corrosive (chlorinated) environment particularly when used for egress of the air volume
Very often one loses focus as to the purpose of venting a wet area.
The three principle concerns are,
moisture (absorption into the building fabric eventually causing material rot and contribute to unpleasant odour).
precipitation ( which presents itself as indoor rain dripping down walls and glass)
odour (that presence that has you forever running for room fresheners before the guest(s) arrive.
The phenomena of indoor rain, known as moisture precipitation, is a situation brought about by the sharp contrast of thermal differentials between inside and ambient, occurring principally of an evening during frost conditions being zero movement of air
The spread of odour created by varying forms of chlorination, mould etc.can also contribute to a degree of discomfort throughout a building particularly those of a residential situation where the natural inclination is to close everything up when the building, or area, is unoccupied.
The problem of odour can only be resolved by air washing (ventilating) the area so as to offset any mould and mildew as might grow as a consequence of moisture saturation in the building materials.
The air volume exchange need to be proportional to the moisture level in the air as well as temperature.
The higher the temperature the greater the venting air flow potential. This does not mean that the flow of air needs to be high velocity but higher volume.
In initial building design, careful consideration as to the nature and character of the area ultimately determines the necessary equipment required to establish the correct ventilation dynamics deemed suitable to the area.
In retro fitting, a complete and accurate assessment of the existing dynamics is required before the solution can be determined. This can be a costly affair in contrast to the implementation of natural ventilation during the initial building construction phase.
It usually means that you’ll end up chasing your tail because as you resolve one issue, another takes it’s place, as a consequence of the ventilation solution employed in the first instance.
Then you throw your hands up and install a high velocity fan, in the hope that it will resolve everything and when that reveals itself to be less than ideal you’ll put the house up for sale.
In conclusion, ensure you do not resolve the problem by creating another problem.
It is fundamentally important that wet areas are able to ventilate efficiently without dependency on equipment such as de-humidifiers, fans, and / or other mechanical services, particularly in commercial facilities, when the area is not being used.
Do not presume the architect has the knowledge required to resolve or address the aspect of ventilation in a Swimming Pool / Spa enclosure as the dynamics are unique to the individual area.
Today the concept of indoor bathing areas and the benefits to be derived from them is taken for granted. Unfortunately the necessity of ventilation is forgotten until all manner of problems arise.
Odour, in particular, heralds the reality that something is wrong and has been for a while.
Deterioration of building materials, due to excessive moisture absorption is a common occurrence. The lack of appropriate ventilation brings about costly repairs, which could have been prevented.
Correct ventilation of enclosure design is paramount in ensuring that the building provides the maximum benefits whilst requiring minimal maintenance. Too much is made of trying to have the swimming pool enclosure conform to a design theme without appropriate consideration to the essential fundamentals as is required for wet areas, heated or otherwise.
Wet areas need continuous and effective ventilation, and in an appropriate manner. Fundamental to venting a pool enclosure is peripheral air entry 400 mm from ground level, and a central convergence of the air mass discharging to atmosphere. The higher the peripheral air ingress, the greater the incidence of moisture precipitation within the building, especially with a heated water mass.
Cross Flow venting is inefficient and never appropriate for heated enclosures. Mechanical venting such as exhaust fans are only capable extraction whilst on and can never be as effective or cost efficient as an appropriate natural system.
Whilst drafts may be considered to be a form of ventilation they should be avoided as their presence often promotes thermal shock giving rise to colds and other respiratory problems.
The one aspect that is continually overlooked is that ingress of dust into any area is proportional to the air volume entering the area.
This is why a natural balanced flow according to the needs of the area should be understood rather than uncontrolled ingress by any means.
If this has assisted please advise of such