After receiving the project's review we are asked to provide outdoor delivery rates.

The project was flushed out with a 2,000 CFM fan for 48 hours with windows and a door open providing a flushing with 5,700,000 cubic feet of outdoor air (5,000,000 cubic feet is required for the project's area.)

We are attempting Option 1, Path 1 and in compliance with internal temperature and humidity.
What is the accurate way to provide outdoor delivery rate as the building uses natural ventilation?