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

This is called positive or negative pressure ventilation, and firefighters use this to vent smoke from buildings.

My fire training said 3 to 5 feet in or out of the opening (the cone of air pushed should overlap the entirety of the hole it is being pushed out), but that is dependent on the volume of air being pushed/pulled by the fan and the amount of air needing to be moved.

Make sure you open a window on the general opposite side of the building for more efficient venting.