So apparently wifey plan of just leaving. The door open I'm on her new green house don't quite work and she baked about $70 with of new plants .... So need to ventilate the thing ... Wanted to see what everyone likes for that when it comes to the smaller ones .

Looking on Amazon they have these deals that will like automatically pop open a lil window at a certain temp and down require any batteries or anything but they also have solar fans like what I have on my quail tractor that you can set to go off at a certain temperature range .... What would probably be better ?

I have both. But if you get a few of those that are the pistons that open with the heat, they will work fine. You have to calibrate them a little. Screwing them in or out gets you to different temperatures. They work great. The two I have have worked flawlessly for 6 years or so now

Also have the solar in there too. It failed. Got another on warranty. If I would do it again I wouldn’t have got it

Grew up with parents running 12 large greenhouses as a business. An approx 150' x 30' greenhouse was ventilated by 2 large exhaust fans in the back and 2 matching size louvers in the front. Back fans would pull the air out and the front louvers opened to allow cooler outside air in. Keep the plants that do better with the cooler intake air in the front and plants that like the heat in the back. After years of moving things around you figure it out.

I would set up something similar to that on a small scale if it were me. Guess to answer your question though, you need both a window and a fan. Open window on one side, fan on the other.

They use beeswax in the cylinders that open and close greenhouse vents. It expands and contracts at the temperature plants do best at.

Keith