Hang on there, young Pada-wan. You are looking at this "problem" from the wrong end! To begin with: you don't really want "fresh air". Stale house air has got more co2 in it, and it naturally sinks into the basement. All you need to worry about is venting the hot exhaust air out - maybe you could vent it though the furnace exhaust vent. This way the "Cold Canadian Winter" isn't a problem.