The temperature drop that these fans can achieve is dependent on %RH (relative humidity) of the air. For 60-70%RH, temperature drop is around 5 degree C.
For Evaporative Cooling fans, the main operating cost comes from electricity consumption of the fan motor. So we can roughly estimate operating cost directly from the power rating of the fan motor stated in the catalog. For a 200W fan motor, the operating cost is typically around 1 THB/hr (assuming 5 THB/kW*hr).
Evaporative Cooling fans can be used in enclosed space, as long as there is sufficient ventilation.
Provided that there is sufficient ventilation, the increase in %RH due to the use of Evaporative Cooling fans is minimal, typically in the 1 – 2% range.