Option 1 is about flush-out. I’m interpreting path 1 to be that a certain volume of air is supposed to pass through the system before occupancy and path 2 to be first a volume before occupancy and then a flow rate for a time after that.
But when reading the units, this does not make sense. And also the units are different in American units and SI units. The American units state just like I said above – a volume. But the SI units state a (very high) flowrate instead of a volume. cf per sf does not translate to l per s and m2. It is supposed to say l per m2 or?