In the same way that passive solar design uses the sun to heat buildings without mechanical equipment, natural ventilation design uses wind and thermal buoyancy to cool buildings without air conditioning. In most climates, a well-designed naturally ventilated building can maintain comfortable interior temperatures during summer without any mechanical cooling, with significant energy and cost savings.

Natural ventilation works through two mechanisms: wind-driven ventilation, in which wind pressure on the windward face of a building pushes air through operable openings and pulls it out of openings on the leeward face; and buoyancy-driven (stack) ventilation, in which warm interior air rises and exits through high openings, drawing in cooler outdoor air through low openings. In most designs, both mechanisms operate together.

Effective natural ventilation design requires that cross-ventilation paths be unobstructed through the building plan, that high and low openings be provided to enable stack ventilation, and that the building’s thermal mass moderate daytime temperature rises so that the building does not overheat before evening ventilation can flush the accumulated heat. In arid climates, evaporative cooling through water features, planted areas, or dedicated evaporative coolers supplements natural ventilation effectively.