On page 102 of the Vanabode book you write, "The picture shows the vent in the raised position with the fan running to pull cool air inside and expel hot air."
Does that mean you are running the fan as an intake and allowing air to be expelled through open windows and/or doors? Or vice versa, running it as an exhaust fan and allowing air to be sucked in through open windows and doors?
What happens when it's time to close windows and doors for the night? Or if there are a lot of flies and insects so windows and doors have to be closed during the day? Does ventilation suffer?
Do you think there would be much to be gained by installing two roof vents, one wired as intake, the other wired as exhaust?