Joe Fischer wrote:

No, I don't think so. I was pointing out that dewpoint is a much better
measure of the amount of moisture in the air than RH.

Aren't they related?

Sure. Tdp (R) = T(R)/(1+T(R)ln(RH%/100)/9621.)

I think the weather man here shows dew points when
there is storm danger.

Pilots suspect fog if the dew point is within a few degrees of the air temp.

Is Nick a window salesman? :-) :-)

No...

I have no idea how to proceed if I were to try to approach
the dry air at night in winter problem by trying to control ventilation.

Airseal your house.

Nick