This is kind of back to the beginning of this thread where you were talking about your solar powered roof vent openers. There is no need to "seal off" this part of the greenhouse. You can remove the wax cylinders for the winter. I would also come up with some kind of plan to secure the roof vents so that they don't blow open with the wind. To remove the cylinders you usually just unscrew them using the thumbscrew, but check on the specific brand that you have.