I have used a rather crude approximation. I add the fan power consumption as extra plug load with appropriate scheduling and use ASHRAE Std 55 enhanced air velocity models to estimate comfort - assuming ceiling fans given air velocities greater than or equal to 1.2 m/s when required numbers are there in a room.
Recommended number of ceiling fans in a room - you can check out this info from building codes (particularly, National Building Code of India)
There must be better ways.