We are working on a 9-story residential project that is being certified v4 BD+C: New Construction. The spaces (including all dwelling units) are cooled by VRF indoor units and heated by radiant floor with hot water coming from a central boiler.

For the dwelling units, We are considering ASHRAE 62.1-2010 as indicated by LEED v.4. However, we have the following concerns:

ASHRAE 62.1-2010 - if we use this standard, we will follow natural ventilation, which also requires mechanical ventilation:

1 - The standard, in section 6.2 states "The outdoor air intake flow for a ventilation system shall be determined in accordance with Sections 6.2.1 through 6.2.7", therefore we understand that outdoor air must be supplied to the dwelling units  (either to one space or to all occupiable spaces). However, LEED v4 Reference Guide states on page 618 "Provide outdoor air to each unit directly from the outdoors. Project teams using exhaust ventilation systems must specify how outdoor air is delivered at the flow rate required by ASHRAE 62.1–2010. Do not use systems that rely on transfer air from pressurized hallways or corridors, adjacent dwelling units, attics, or elsewhere."

So, can the exhaust airflow rate,  for the bathrooms and kitchens, be credited toward the outdoor airflow rate requirements of section 6.2 of the standard?

2 - It's not clear for us where the outdoor air has to be supplied within each dwelling unit as OA requirements are calculated for the entire dwelling unit as a whole. Can the outdoor air be supplied to only one space in each dwelling-unit - e.g. living rooms only? Or does it have to be supplied to each occupiable space - e.g. bedrooms and living rooms?

3 - The outdoor air supplied to (or exhausted from) the dwelling unit (either to one space or to all occupiable spaces) must be supplied 24/7 or can it be on-demand when the users occupy the dwelling unit? 

Any insights or experience on this would be appreciated.