Natural Ventilation

We have a four story office building with natural ventilation. All the rooms are single-sided. We want to show that the window area is big enough to exceed the ASHRAE requirements by 30%. 1. What case applies, the buoyancy or the wind driven one? 2. Where can I get the C and wind speed values from? Even if I had the weather data the wind speed will be different depending on the height and orientation of the room. 3. What kind of documentation is required in order to submit the credit? Thanks for your help!