2 fans or 1?

[ilbasso]

This is where my little greenhouse is:

I am planning on building a box to raise it up to where more shelves are in front of the window. I was thinking that since the bottom is open and wire, then I may install a fan in the top of the box to help circulate the air.

Should I also install a second fan blowing air out of the greenhouse to help the circulation more? Any thoughts on what size fans would be good for something like this?

 

[nepenthes gracilis]

Air circulation is definitely important but air exchange in a tight enclosed space like yours is even more important. I would install one fan in the highest point possible and have it on very low speeds to ensure a gradual air exchange. Once your plants become accustomed to it, it will be very beneficial to future wellbeing of them.