Whirlybird Vs Attic Fan

How much air must be moved.

Whirlybird vs attic fan.

The average domestic whirlybird moves around 100 cbm h at around 12 km h wind speed. Roof vents vs whirly birds. The sun does that. A solar fan doesn t rely on the wind and it actually has a more powerful motor in it so it keeps the temperature of your attic regulated regardless of wind conditions.

A solar fan is able to actively pull more air into your attic than a turbine can. In summer air movement helps rid the attic space of. It is hard to find this kind of data from the manufacturers of the wind driven fans but there seems to be a consensus when surveying the different solar powered roof ventilation fan options that they are equivalent to 10 to 30 whirlybirds. Of vented area for every 300 sq.

Although they don t work at night due to the lack of sunlight this is typically a non issue because they re most needed during the day when the sunrays are heating up your roof and attic. The whirly bird or turbine vents are worse than useless. Without ventilation unfinished attic spaces can end up having stagnant air. Solar fans don t require any electricity wind or attic pressure to spin.

They make noise too. Without any air movement temperatures in the attic soar in summer and plunge in winter. With this said neither the turbine nor the ridge vent will act upon moisture. When considering ventilation for your attic it is very important to take into account moisture as well as heat as mold growing inside your attic is much worse than mold growing on the roof shingle surface on the outside.

Since your solar vent fan only moves 500 cfm a third to half that of a typical hardwired attic vent fan it probably won t move enough air to reverse the action of the ridge vent. Full length ridge vent in combination with soffit vents is best. It is a con to make people think the spinning action is like running a fan and mechanically drawing hot air out. Also since the fan is powered by the sun it should turn off when the sky is overcast during a storm which will keep it from drawing rain into the attic.

A largely arbitrary rule of thumb that s been adopted into most building codes calls for 1 sq.