That's good to hear. Not only will it keep the temps under control, it will help with air movement. You should probably have at least one fan hanging that will move air inside. One of the major things that help a plant get stronger is something that most people don't even think about. The wind blowing. Everyone will have their own ideas of what fertilizers to use or how to start cutting, what soiless mix to buy or even semi-gritty stuff, but the wind plays a major role in strengthening a plant. When you have any plants that will end up growing outside, they need air movement. If you do a little homework, you will find that 2 would be best. One on each side blowing in opposite directions, so you will have the air circling. It will actually help to change the directions back and forth every month or so. I know I'm just a country bumpkin, living in the sticks, plus I don't know some of the big words but this is something I heard someone talking about before. Did you notice that I got your semi- gritty stuff thrown in there.lol
I know you probably already know this, just trying to help you decide in doing the right thing in finishing your greenhouse. Back to the Nike thing again.
PS: Could be you might need 4 fans, just smaller in size. Maybe go to the greenhouse site to see what they recommend.
luke