Turbines for vents

My grandfather suggested that i use roof turbons that people use on top of their roof to release heat from attics and put it on top of the greenhouse to release heat. He said they dont use electricity. The heat from greenhouse would make turbon turn and pull heat out of greenhouse. What do you think?

In summer that would work, but what would "hold" the heat in when it's cold?
I'm mostly using mine for overwintering & starting a few seeds in early spring, I would not want the heat excaping. I do open & shut it as the sun comes out & night falls.

well--papa told me to stuff it with something---like plastic