Mankind has known the Evaporative Cooling Technology for a long time. However, Direct Evaporative Cooling (DEC) systems have been greatly under utilized by the HVAC industry, in part because of the concerns regarding the negative effects of these systems on the Indoor Air Quality (IAQ). On the contrary, the IAQ in buildings can, in fact, greatly benefit from the design and installation of DEC systems through the introduction of 100% Outdoor Air. DEC rigid media further improves IAQ by acting as a good filtration device and also as a sound-attenuating device in noise-sensitive applications. In addition to IAQ benefits, the DEC can help achieve energy savings by providing both free sensible cooling and beneficial winter humidification. DEC can also be combined with Indirect Evaporative Coolers (IEC) to provide further energy savings by increasing the refrigeration free cooling hours in hot and dry North American climates. This paper will analyze the annual DEC system performance for different climate zones in various cities across North America.