crossventilation

Crossventilation, also called cross ventilation, is a mode of natural ventilation in which outdoor air enters a building through one opening and exits through another opening on the opposite side. The resulting cross-flow removes heat and stale air from interiors, helping to cool spaces without mechanical ventilation.

The effect relies on pressure differences produced by wind and by buoyancy from indoor-outdoor temperature differences. Wind pressures push air into the building on the windward side and pull it out on the leeward side, while warmer indoor air tends to rise and escape through higher openings, drawing cooler air in through lower ones. In practice, cross-ventilation is most effective when openings are aligned with prevailing winds and placed on opposite façades or at different heights to exploit both horizontal and vertical air movement.

Design considerations include the size and placement of windows, doors, or vents; the distance between openings; the presence of interior barriers or courtyards; and external factors such as nearby buildings, landscaping, and street layout. Weather protection, security, noise, and the potential for drafts must also be considered. To maximize performance, architects may combine operable windows with vents, balconies, or wind scoops and ensure openings can be easily controlled.

Applications and benefits include reduced cooling loads, improved indoor air quality, and enhanced occupant comfort in warm or moderate climates. Limitations arise when wind is weak or irregular, in densely built environments, or during extreme weather; cross-ventilation may not provide sufficient cooling or ventilation without supplementary strategies. Measured effectiveness depends on factors such as wind speed, opening areas, and building geometry.