[hayden55]

Redpoint you have a lot of issues with that kind of setup in a house. That smell downstairs is mold from lack of humdity control. Concrete is vapor permeable so it lets in moisture. Stay between 30-60% year round. So your top house gets solar gain on the walls and roof year round, your lower house doesn't and even gets the opposite effect. The concrete leaches out heat, a lot in the winter, and not much in the summer, but no solar heat gain since you're below ground. The big heat loss is really in the 3 feet below ground area and below that i think ground temp is more or less 55 degrees year round. Also, houses breathe upwards so heat will always go up.
Look into manual J calculations and see how far off you are right now. Also look into air sealing and blower door test even updating or improving your insulation strategies, and look into a paint on vapor barrier for the basement

I know the new equipment is so good im looking to swap my oversized furnace, 10 seer ac system out to a new air source heat pump one day and then when my whole house is electric and efficient and balanced as i can get it i will swap to solar as i will have the most balanced load with the smallest solar system