Yes, maybe my clumsiness of expression. I know that ventilation works by way of hot air rising and escaping from high vents. Old houses had these vents in every room and I lived in one. As the hot air escapes, the cooler air is drawn up to take its place. Therefore with aircon working downstairs, this should make upstairs cooler. The Solar Whiz is not just ventilation.
"The
Solar Whiz whirlybirds works like solar whirlybirds. The solar panel powers a fan that actively pumps hot air out of your roof up to 21 times faster than a traditional whirlybird. The fans come in different sizes. A solar powered roof ventilator can significantly reduce your cooling costs by using solar power to actively pump the hot air out of your ceiling, replacing it with cooler air. If you use a ducted cooling system (A/C or evaporative cooling) you will notice a significant improvement in efficiency after installing roof ventilation, as you dramatically reduce the heat gain in the ducting throughout the roof." (quoting from website)
They have a thermostat so they don't take out the heat in winter when the sun is shining. A night switch can be added (which I've done) so that the whiz continues to remove heat through the vents installed in the ceiling of the rooms, plus the heat rising up the staircase throughout the evening, the emission of heat via the glass, the walls, the furniture etc so that when the sun is up the next morning, the solar component is then generating the power to perform. Theoretically, the day then begins after an evening of pumped out heat and much cooler than would be the case if the fan was not operating throughout the evening. Without this heat loss throughout the night, the roof will still retain significant heat. Not unusual for it to be 60 degrees or more at the apex of the roof. The thermometer on the lip of the open manhole registered at 4pm 40 degrees when it was 27 degrees outside.
