The good old ventilation issue

[Yéri]

Hello everyone,

I'm not that active on the forums, but I pay a visit once in a while

I'm moving through the last stages of building my "greenhouse", but I can't help but notice (and especially now that winter is at our doorsteps) a certain...unhealthy feeling to the atmosphere inside my greenhouse.

I started off with a tower fan (see end of post) and opening up my door every day for fresh air. This helped avoiding fungi, but always caused a drier period during the day. Combined with a central heating and young plants, this wasn't the ideal solution.

So I added 2 ventilation grills:
One on top at the end


And one below on the other end of the greenhouse


And in order to take advantage of that aeration, I decided to replace my tower fan with 2 smaller fans


Check out the specs if you like.

I installed on at the ventilation grill below, and one on the other end of the greenhouse, but opposite to the ventilation grill there


This in order to have a good airflow rotating through the whole greenhouse.
Here's a panorama of the greenhouse, with my old bigger fan on the red arrow and the locations of the new smaller fans on the yellow arrows (I hope it's not too confusing). The greenhouse itself is roughly 4m x 3m x 2m


Now that I've given you an idea of my setup, let's move onto the issue itself...
I can't shake the feeling that those small fans aren't going to cut it. They do cause some air movement, but it doesn't seem much to me.

On the other hand, my big fan seemed to cause to blow too hard, and as it was in a central position and on the floor, I think I was creating pools of stagnant air.

So here I am, asking for your opinion!
Now that you've seen the airflow the small fans cause (in the specs), do you think this would be sufficient for my setup?
Or would there be another kind of fans I could use, more appropriate to my needs? (I'll add that I can't install a ceiling fan, I'm not the proprietor of the house and I'm not allowed to make holes in order to hang it)

I know it's all a bit vague! I've been reading several articles and guides on how to have correct ventilation inside a greenhouse, but I'm still doubting myself.

As always, advice from firsthand orchid growers is so much more valuable than general guides.

Best regards and happy holidays

Yéri~