Natural ventilation can be encouraged through a technique called the stack effect. To set up this system, an opening at or near the top of the building is needed in conjunction with openings near the bottom so that hot indoor air will be drawn up and out. The greater the height and the bigger the temperature difference, the greater the natural draw. In an existing home, installing an operable skylight near the peak, combined with lower windows, creates the elements needed. A two-story house with a central stairwell is ideal for stack or “thermal chimney” cooling. Opening windows on the windward side or alternatively on the north shaded side while opening upper windows or skylights allows control of these cooling air flows.
The stack effect can be magnified by adding a solar chimney or tower to increase the height and temperature differential. The sun shines into the high section of the chimney landing on a dark surface, thereby boosting temperatures. This causes the vertical draft to work even more effectively, using the hotter air at the top as the “thermal engine” to drive the conductive flow.
Electric fans are another great way to create air movement within a home, especially when there are few breezes outside. Although not a part of the natural cooling lexicon, it is a low-tech, eco-friendly cooling technique. Ceiling or Casablanca fans use minimal electricity, are easy to retrofit in existing homes, and cool effectively. Look for high efficiency and high airflow (cubic feet per minute per watt, and air movement per watt). Make certain the unit you choose has good wind speed because that is what produces the cooling sensation on one’s body. According to Environmental Building News, the Haiku fan, developed just a few years ago, has the highest rating with its great aerodynamic blade design and super-quiet, super-efficient motor.
Another alternative to air conditioning is evaporative cooling, which operates with much less energy than compressor-driven AC. These devices, which are often called swamp coolers, are only effective in dry climates because they work by removing heat through evaporation. They move a lot of air, so pay attention to the noise rating. The only negative is they require periodic cleaning.
Taking advantage of these basic cooling strategies saves money and energy, plus it lets you live more in tune with the natural rhythms of the environment.