Although the example of forced air furnace was used that poster neglected to acknowledge that cold air is returned from heated areas than brought into the plenum to be reheated and forced into rooms
I was mostly responding to the comment the "
only" way to solve this was to remove cold air. Which is "structurally" misleading in advocating the forced moving of cold air only.
But since you mentioned it...
Because in this case, from the information provided by the OP, that is in the issue needed by the OP, the cold air will move along the cold level gradient, where dense cold air lives .. i.e. the floor. But do so in a way that is probably not as noticeable, or as uncomfortable, as blowing cold air from room to room with a fan.
By moving warm air, one is moving kinetic energy. The air temps in the house of the small size shown by the OP will really take care of themselves. The OP clearly does not have a "standard huge" American home. Yes, that matters.
Moving air through a basement is indeed "ideal", but is probably overkill given the floor plan, even if the OP has a basement.
AND it assumes the OP has a basement. The OP did not say. And not all houses have basements. Don't make assumptions if the OP did not say they had a basement.
In others words, I assumed what I said was obvious given the provided information, without assumptions (I did not assume a basement). Thus a no brainier. And workable from experience by anyone who tried what I said. Again, given the OPs circumstances as stated. And thus needed no explicit explanation for most thinking people.