We remodeled to tight envelope + radiant heat but our architect failed to spec fresh air ventilation. We had to DIY it mid remodel and learned a lot in a hurry.

The one room that we didn’t get any fresh air flow to, now stinks. The others are fine.

In a nutshell: blow fresh air into bedrooms / closets. 10 CFM is enough (small cpu fan level of airflow). Exhaust with quiet bathroom fans on constantly at low CFM. In + out = flow. Rooms with no flow = stinky, musty, germ contamination, good for growing mushrooms, bad for people and pets