Natural vs. Mechanical Ventilation for Warehouse

We are currently working on a warehouse project, where each level is 'naturally ventilated' according to the local code (in Singapore); there are more than 5% openings, but the floor plate is very deep, meaning more than 100m. I really doubt that this can be considered a naturally ventilated space as per ASHRAE 62.1, even by engineering calculations. I have 2 questions: 1. If we were to try and demonstrate the design is efficient for natural ventilation, what kind of submission/calculations should we show in this case? If we conduct a CFD, are we supposed to prove fresh air rates usually achieved through mechanical ventilation are achieved through natural? 2. The mechanical engineer wants to provide fresh air fans with a long throw range, to avoid ducting. Would that be acceptable to provide the fresh air requirements? Will there need to be a CFD backing up the fact that wall mounted fresh air fans manage to renew the air adequately in all spaces of the warehouse? Thanks in advance for your answers.