> You have to have a system to cycle in fresh air in a way that it heats/cools it with the air that is leaving. This is quite nice regardless. Houses are unli

> You have to have a system to cycle in fresh air in a way that it heats/cools it with the air that is leaving. This is quite nice regardless. Houses are unlikely to be so drafty that the air inside is always fresh, and a real ventilation system will deliver fresh, filtered air all the time. > You also need a makeup air vent for things like a stove hood. You need this anyway, at least in CA, if your hood exceeds 400cfm, and it’s probably a good idea regardless. Sadly, high end hoods seem to mostly have way too much airflow, and decent makeup air systems are rare and complex.