We have a central Air Handling Unit supplying 100% outside fresh air to all the rooms in a building, e.g offices, meeting rooms, conference rooms, etc This air will be tempered to say 18 degrees Celsius - provides min fresh air requirements.

This fresh air is supplied to the back of Fan Coil Units in each space, some spaces may have more than one Fan coil unit. The fan coil unit will supply the additional heating / cooling required. Its a constant volume system. Based on this my question is should this be considered as (1) Single Zone Unit, (2) 100% Outside Air or (3) Multiple Zone Unit in terms of the credit form.