The free cooling method is composed of two main systems: the air-side economization and the water-side economization. The first one basically uses the air that comes from the outer environment in order to control and adjust the desired temperature in the IT apparatus. This technique is quite productive with respect to its cost (since we just take advantage of air from the external environment) but on the other hand has some disadvantages since it is likely to provoke humidity and moisture in the data center.