Since the emergence of fan ventilation for sub-floor (basement) areas, it really is not just an option, it is a requirement. Pest control, pest management industry stresses the importance of effective cross-flow ventilation (adequate ventilation) in sub-floor areas in line with the termite inspection report in accordance with AS 3660.
The other fact is that when an anemometer is placed (a free spinning wind speed apparatus) against a wire mesh vent, the impeller will move clockwise for a time and then anti-clockwise. The conclusion is that wire mesh vents work omni-directionally with a push pull motion. When all vents are doing the same thing turbulence is present and not cross-flow ventilation in sub-floor area. Natural ventilation is not effective enough, something more is required.
Therefore if the client asked the pest controller, that what would the installation of passive vents do at around, say $130.00 each and one were to install ten. What are the benefits? Would it create cross-flow ventilation? No. Would it aerate my sub-floor adequately? Probably not. Ah yes but is it better than what you had? Yes, true, but by what percentage? Perhaps around 20-25 percent.
A lot of clients that have had wire mesh vents installed and the wire mesh vents by themselves did not resolve the clients problem, cross-flow ventilation was not achieved and the client still has a problem. So why does the client now have to invest twice for the same problem? The other factor that plays havoc in the city is that buildings are virtually on top of each other, so the building next door or the fence line is going to inhibit air flow through a wire mesh vent for it to work effectively.
Fan ventilation is an effective way in removing moisture from sub-floor areas because when the experienced ventilation consultant looks at a passive vent and cannot tell you which way the air is travelling through it. However with fan-forced systems there is no guesswork. So do not leave it to chance to ventilate the client’s underfloor area, get the big guns in and let it do the job and take control.
Once the systems are installed, it is only going to do one thing and that is it is going to extract the damp air out, which causes rotting timber flooring structures and flooring (dry rot), cupping of floors, unpleasant musty smells in the home, unhealthy environment in the living areas, which will affect the respiratory health of the occupants, high humidity in the sub-floor area which can encourage termites sooner than later, health problems encountered due to cleaning solutions in removing mould & mildew inside the living areas and so on. Fan ventilation will extract these unhealthy and unwanted nasties from sub-floor areas by effective sub-floor ventilation.
So if passive vents only are used it will deliver only marginal results, however why not get it right the first time with couple fan ventilation systems with wire mesh vents. It will do what you want it to do, then cross-flow ventilation will be achieved no ifs or buts.
The mechanical vent is a well thought out product in that it is the size of a brick or terracotta vent. Installation of mechanical ventilation systems does not alter the structural integrity of the building. By doing a retrofit (no building license required) to terracotta vents or installing in sub-walls, one would replace it with a 12volt (low voltage) system the same size. If the dwelling has raked out purps in the brick work, one would extract one brick and install the 12volt (low voltage) brick size system. The great news in that by incorporating these systems there is no need of flexible ducting, so the air can move freely throughout the sub-floor area.
The uniqueness about this product also that it can be solar powered (no running costs) however, if you do choose to operate it on a 12volt power system it will consume around $3-00 of power per year. It is also quiet due to its brushless motors and is water resistant and an Aussie owned product. With any of the Envirofan products one will not need an electrician, (cost saving) as it is all low voltage (12v) and will not electrocute yourself.
The mechanical ventilation systems are well priced also, considering it is a low capital investment toward the major investment (the building) considering the damage damp problems and termites can cause.
With expertise in pest control and pest management and having the right apparatus in sub-floor ventilating systems incorporated into the termite prevention regime this would be a winning combination in the prevention of sub-floor damp and humidity.