Hello,

We are currently working on a LEED EBOM project at our University campus. This building has two air handling units (AHU), one serving the north and the other serving the south side of the building. The design of the AHUs is such that they supply a 100% outside air. The air is vented out of a ventilation shaft or open windows through positive pressure. There are approximately 34 offices in the north side, 41 offices in the south side and a total of 36 meeting rooms in the building that are served by these 2 AHUs.
ASHRAE 62.1 defines zones as areas that have similar occupant and building outdoor air rates, similar occupant density, and similar zone primary airflow rates. Almost all of the 75 offices differ in their size and occupancy thus all of them will have to be considered as different zones if we are to strictly follow ASHRAE 62.1. The meeting rooms too are different in their size and capacity.
The question I have is do we have to just measure the 2 AHUs and see how much outside air they pull during normal operations or do we have to measure the air flow in each of the offices and meeting rooms? I am not sure if this has been addressed before but I would really appreciate your clarification on the above question.

Thanks,
Michelle