I have a passive house with air ventilation and heating in the floor. In the question of the temperature of the air and the floor I have found the optimum, but I'm absolute without any knowledge, how to set up air humidity. The system allows me to setup humidity in percentage value. Is it any different in the summer or winter? What is the best for the ventilation system? What is the best for the humans living in the house?
Human comfort depends mainly on the combination of temperature - humidity. And the optimum varies depending of the physical activity, clothing etc.
The 'tool' used to know whether you are in the comfort area or not is a Psychrometric Chart (name fixed).
Assuming 'standard' home activity and clothing the 'sweet spot' for comfort is 20 degrees C and 40% relative humidity.