WHIRLYBIRD THEORY

Basically, the whirlybird is driven by wind power and the turbine effect creates suction from the inside toward the outside. This means you can effectively suck moisture in the air, condensation and hot air from your roof cavity and recirculate it with cooler air from below. It has some drying effect as well. If you have quality insulation it will assist by reducing the temperature differential above and below the insulation. This will make your home more comfortable and will assist in power savings too. Under eave vents should also be installed, particularly on iron/colourbond roofs.

Roof – cavity mounted air conditioning systems will appreciate a lower ambient air temperature in the roof cavity particularly when 60 degrees plus is not uncommon during our summer.
Moisture and condensation come mostly from the kitchen and bathroom areas.

The following diagram may be helpful;

In Winter moisture laden air is being sucked out. In Summer heat laden air radiating downwards is being sucked out.

Under eave vents must be installed to provide sufficient air flow to allow the whirlybird to work at best efficiency.