Climate Control Through Evaporative Cooling

^Image source: Kwok, The Green Studio Handbook, page 151

To me, the most interesting new method introduced by the Kwok reading was the evaporative cooling tower. This is the first time I have heard of such a system, and the idea is immediately attention-grabbing while still being functional on an important level. Operating in nearly the polar opposite way of a chimney, evaporative cooling towers expose hot dry air to water at the top of the tower, causing its temperature to drop and its moisture content to increase. This dense air is consequently drawn down the tower and through an opening in the base. Constant suction of air downward through the tower ensures than air continues moving as long as the humidification process continues. 

The benefits of utilizing an evaporative cooling tower are tremendous in terms of reducing money spent on mechanical cooling systems. However, they are suited almost exclusively to hot, arid climates such as the southwestern United States. Such a climate is ideal in regards to the need for a large supply of dry air, but the large amount of water that is often required by these towers could be a problem in areas where water is scarce or rationed. Also, Kwok notes that performance of the tower is often dependent on the difference in wet and dry bulb temperature. The greater the difference, the greater the air flow through the tower will be and the more effective its cooling performance will be. This characteristic requires that the towers height and amount of water consumption must be tailored to the specific climate of each usage.

Above is an example of an evaporative cooling tower that is incorporated into a small home on a Navajo Indian reservation in Arizona. The structure uses the tower in conjunction with the cool nature of its adobe structure and the surrounding ground to keep the home insulated against the hot desert climate. The tower itself is coupled with a wood stove at its base to which it provides ventilation in the winter when the desert nights can become very cold.