Derivative sensor for humidity control

Hi, I couldn’t find a sensor that would calculate the derivative of another sensor. So I’ve hacked that function into the existing statistics sensor.

Is there a better way?

My Usercase is the humidity in our basement. We’re hanging our freshly washed clothes up to dry. That’s not a problem during the wintertime when the heating system (that sits in the same room) is on and therefore regularly exchanges the air in the room.
But during the Summertime humidity skyrockets.
I’ve installed a humidity sensor to control a vent but quickly realized that humidity is also massively affected by the weather outside.
A simple rule like “turn on once humidity is above 60%” didn’t work. I figured that the derivative of the mean (to reduce reaction on spikes) would make far more sense.

This seems to work quite well at the moment.
Any input?