I am building a cape cod over a finished insulated basement. My source of heat is a woodstove in the center of the basement, with the warm air being circulated to the second story through an open staircase assisted by ceiling fans.  I’ve heard that in order to get the air really circulating I should put cold-air returns in the walls ( running from the second floor to the basement) to allow the cold air to fall a different route than the warm air that is trying to rise.

What’s the simplest most effective way to accomplish this, duct or PVC or something else? I need to install it before Monday as the insulators are coming to blow in foam.Thanks for the input…Also I was thinking the register should be located near the floor of the second floor and exhausting near the ceiling of the basement, is this correct thinking?