You can use a louver to provide natural ventilation in Florida. The free area must be 4% of the floor area. You would want to size the louver for the free area and not the CFM. In your case you would want a louver with a free area of 12 sq/ft. That's a large louver. Are there any operable windows in the building? Maybe you can get credit for those. I have never seen anyone use this code before though.