Correcting ~10% humidity by closing sun room with fan blowing?

[rbarata]

If you want to increase HR, firts you must determine if it exist ans is escaping from your environment.
What is more frequent is to have naturally low water content in the air. In this case, one must find ways to evaporate it in the environment (humidifier).
Increasing air flow will make it evaporate faster from surfaces but, if the environment is closed, it won't make the HR decrease.