Whirly birds do work to cool the house

[Mr 672A]

I installed 5 CSR Whirlybirds on the roof last week and I can tell you this they certainly do work to keep the house cool. I installed three one day and waited for the old body to recover to install the remaining two. Money well spent @ $117 each.
The house is just under 35 building Sq.

[mtv]

Any form of roof ventilation helps cooling.

The better ones have flaps that close to prevent warm air from escaping in the colder months.