In the Building Science America series unvented attics are recommended; "as long as they have airtight ceilings and the ductwork is not in unconditioned space". So how do you put in ductwork in conditioned space? I don't really want to use spf around the whole ductwork. Burying it in FG or cellulose doesn't keep it from causing condensation when it carries the air conditioning. Where is the ductwork to be placed?