Ventilation Questions

I Have problems with money and I have everything else to grow except a inline fan to venf the grow room but I do have a window that I can open when needed is thid good enough? I dont care about the smell.

Open window lets in to many pest, invest, dont be cheap, better crop

Even with a screen?

Forget the fan. Watch for pests like spider mites. And put smaller screening material over your screen. You will need a regular room fan. I have never had an inline fan and grown since 1964. Get after it and good luck.