Heating, ventilation and air-conditioning, HVAC, systems account for 50% of the total final energy consumption in buildings. Directive 2010/31/EU established "to promote the improvement of the energy efficiency of buildings" as the main objective of the Energy Efficiency of Buildings Directive. According to this target, different sustainable solutions such as the use of efficient air-cooling systems or renewable energies sources are proposed in literature. Then, air-cooling technologies based on indirect evaporative cooling could be an interesting alternative to traditional air-cooling systems based on direct expansion unit in terms of energy efficiency. This research work was based on the experimental study of two innovative air-cooling systems in terms of Energy Efficiency Ratio, EER. These systems consisted of a dew-point indirect evaporative cooler, DIEC, and a desiccant dew-point indirect evaporative cooler, DW-DIEC. Different experimental tests were established to compare the EER values of the DIEC and DW-DIEC systems under different outdoor air conditions. The highest EER values for DIEC and DW-DIEC, 10.6 and 9.2 respectively, were achieved for the maximum value of outdoor air temperature, 40 °C, and the minimum value of outdoor air humidity ratio, 8 g kg-1.