传统的直接蒸发冷却器通过加湿空气运行，因此仅在干旱地区（比如美国40%的炎热夏季地区）提供舒适性，但与那里的冷冻冷却相比，可节省60%-80%的首次成本、电力和维护费用。然而，新的间接蒸发式冷却器可以在空气干燥的情况下进行直接蒸发式第二阶段，从而在适度潮湿的地区实现舒适性，也许还有40%的地区需要进行季节性冷却。这种带有小型制冷二级的间接冷却器可以在我们大部分高湿度区域创造舒适感，这些区域大约占整个过热夏季区域的20%，主要是海岸线和密西西比河谷下游。 在中湿度和高湿度区域实现大规模生产之前，相关的两级冷却器可能比传统空调的投资略大，但应分别节省约40%-50%和20%-25%的维护和电力成本。在需要额外通风的地方，在夏季高峰需求造成电价惩罚的地方，以及在冬季间接第一阶段也可以回收废热的地方，这些节约会增加。如今，由于长期电力成本和其他趋势的支持，蒸发式空调显然应该在几乎所有地方得到更广泛的使用。 单位:双引文:研讨会，ASHRAE交易，1987年，第93卷，第。1，纽约州纽约市

Traditional direct-evaporative coolers operate by humidifying air, so produce comfort only in the arid, say, 40% of U.S. hot-summer areas, but save 60%-80% of first cost, power and maintenance compared to refrigerated cooling there.However, new indirect-evaporative coolers which cool air dry can have directevaporative second stages and thus achieve comfort in our moderately-humid areas, perhaps another 40% of our territory which justifies seasonal cooling.And such indirect coolers with small refrigerative second stages can create comfort throughout most of our high-humidity zones comprising perhaps 20% of our total overheated summer area, mostly shorelines and the lower Mississippi Valley.Until mass production is achieved in the moderate and high humidity zones, the related two-stage coolers may represent slightly greater investments than conventional air conditioning but should save about 40%-50% and 20%-25%, respectively, in maintenance and power costs. These savings increase where extra ventilation is needed, where summer peak demands create power price penalties, and where the indirect first stages can also recapture waste heat in winter.Today, with long-run power costs and other trends favoring it, evaporative air conditioning clearly deserves greater use almost everywhere.Units: Dual