With Bernoulli’s principle in mind (I think that’s the right one), is it more efficient to vent a room by putting a fan back from a window a bit, or right up next to it, and if so, is there a general sweet-spot as to how far back it should be?

Question

For context, this would be to vent a basement bathroom with a a window in an old house, and I can’t install a bathroom vent.

In: 857

Answer 1

I would guess it would depend on the size of the window. If you remember the concept of vena contracta for orifices you will have something like that (not the same) with the flow field behind the fan. Ideally you’d match that area with the window. So the bigger the window the further away until it stops increasing the flow.