need help with this ventilation idea

I have a hoop house in Denver, CO. With our intense sun, it very quickly overheats, since there is no ventilation mechanism yet. I have bought an automatic vent opener, and will be installing a vent right at the top of the greenhouse.

However, it would work better if I had a lower opening which could let in cooler air. I was wondering if I attached some sort of opening with flaps over it: would the negative pressure of the rising warm air in the greenhouse leaving the vent pull the flaps open and cool air in?

I would, of course, have to protect the flaps from the wind. I was thinking a pipe with a couple of bends in it would do the trick.

Gilbert Fritz : Face the Hinge to the prevailing winds, and your opening to the lee side. I had some friends who did not and hat the whole venting structure ripped
off of the greenhouse in a very localized wind event ! Thats all I've got ! BIG AL

Put the auto vent opening at the bottom and get one of those attic vent turbines and put it at the top. The hot air rising will turn the turbine which will suck the hot air out whenever it get too hot or the wind is blowing. During the really cold days if you dont want it too operate just put a stick up in it or cover the bottom. Cheap and pretty much automatic. Van