Subfloor Fans and Subfloor Ventilation Systems


gable sub-floor fans on a house

Effective ventilation of the underfloor area is essential to the health and longevity of any building with a subfloor area.

Unfortunately, not all homes and buildings can achieve the necessary subfloor ventilation under the floors through passive, natural ventilation. These houses require additional mechanical ventilation to control humidity. Solar-powered subfloor fans are the most effective way to ventilate underfloor areas.

High humidity levels in sub-floor areas result in dampness, which causes mould, rotting floorboards, rotting stumps and fungi growth. The symptoms for these issues are often odours and musty smells that make their way into the house.

Moist underfloor areas serve as the perfect breeding grounds for termites, white ants, fungi and wood borers. It is therefore of utmost importance to protect your house by ensuring good under-floor ventilation. A well-ventilated sub-floor also prevents rising damp from developing.

Underfloor Ventilation Using Subfloor Fans to Reduce Asthma Symptoms

Asthma symptoms and allergies are often exacerbated by the presence of dust mites in the house. Dust mites thrive in areas with high moisture levels and poor air quality, which are common indicators of poor subfloor health. Such are the flow-on effects as a result of issues in the sub-floor area.

The most common approach to sub-floor ventilation is constant or timer-operated electrically powered fans. These subfloor fans are designed to remove moisture from the sub-floor area, with the aim of allowing replacement air to enter under the house via vents located around the building.

The problem with constant or timer-operated fans is that they also operate when there is high humidity, such as when it is raining. This means that damp air is brought into the sub-floor area, which is exactly the opposite of what ventilation should do.

The lower temperature of underfloor areas compared to the indoor environment causes condensation and high moisture levels in your house. Over extended periods of time, this could lead to the destruction of your underfloor area through mould, rot and termites.

Solar-Powered Subfloor Ventilation Fans

The Solar Whiz gable-mounted fan provides a simple but highly effective solution to underfloor ventilation issues. The large-capacity fan can be mounted onto the exterior wall of the sub-floor and can move up to 3,000 cubic meters of air per hour. This means that generally only one fan will be required to solve most sub floor issues.

Solar Whiz subfloor fans draw in fresh, dry air through wall vents and ventilate it through the sub-floor area. As the air moves across the damp earth, moisture is effectively drawn out and vented outside of the sub-floor area. Ducting can be added to the subfloor fans and is generally extended into the centre of the house or building. This allows the air to be drawn evenly from all sides of the house.

Wall vents may need to be installed in addition to the Solar Whiz unit if there are no pre-existing vents or the existing ones don’t supply enough replacement air.

wall vent in a trap-door for subfloor ventilation

Our solar-powered subfloor fans offer a couple of obvious advantages over the traditional mains-powered and timer-operated systems:

  • The system only operates during sunny conditions. This ensures that the replacement air ventilating through the sub-floor area is generally quite dry. Therefore doing a better job of ventilating and keeping the sub-floor healthy.
  • Solar fans cost nothing to operate.

Global Eco & Environmental Solutions offers a variety of solar-powered sub-floor and underfloor ventilation options:

  • Solar collector ventilation systems
  • 150 mm Solar subfloor Fans – medium volume
  • 300 mm Solar sub floor Fans (in-line) – high volume
  • Solar Whiz sub-floor/gable fan for moisture extraction from sub-floor spaces. Requiring about 500 mm diameter for installation.

If the area under the house is restricted in height and won’t allow the installation of the Solar Whiz, we offer a 150mm diameter solar subfloor fan as an alternative. It comes in two versions with capacities of 300 or 450 cubic meters per hour.

Subfloor Ventilation – Solar Air Collector Systems

Traditionally, subfloor ventilation has focused on removing moisture from underfloor areas using extraction fans. However, GES has successfully solved many customers’ severe damp problems using Solar Air Module (SAM). This is a unique approach to house ventilation that involves using solar air collectors to heat and deliver warm, fresh dry air into the problem areas.

On a clear sunny day, a single solar air collector can deliver fresh heated air with a humidity content of less than 10%. In most cases, we combine the collectors with an extraction fan placed on the opposite side of the house. This helps remove the moist and stale air from the underfloor area.

The dry air effectively lowers the amount of moisture accumulated in the subfloor area. Cross-flow from the system also ensures a much dryer environment in the living areas of the house.

Sub-floor Ventilation – Solar Fan Systems

subfloor fan in brick wall

Wall-integrated Solar Whiz subfloor ventilation fans are a highly cost-effective approach for creating cross-flow ventilation in sub-floor areas. The solar gable fan offers extremely high airflow volumes (1400/2100/3000 cbm/h) with whisper-quiet operation and no power consumption.

Where less space is available – our 150 mm solar fans may be the best choice. These sub-floor fans have the capacity to move up to around 450 cbm/h.

The solar-powered operation ensures that the unit only operates when the humidity content of the replacement air is relatively low. It also prevents operation during rainy periods, which would increase humidity in the sub-floor area and potentially cause more damage.

GES specialises in improving indoor air quality, comfort and health in homes and buildings through solar ventilation.

More information & prices can be found in the Sub Floor Ventilation Brochure.



sub-floor adjusted subfloor fans installation


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