text: Cross ventilation relies on many factors, such as the tightness of the establishment, wind direction and how much wind is available, its potential travel through chimneys, vents and other openings in the home. Casement windows can be installed to improve cross-breezes. Air quality may also affect cross ventilation. 
  Although cross ventilation is generally more direct at its job than stack ventilation, its cons include its effects being unproductive on hot, still days, when it is most necessary. Moreover, cross ventilation is generally only suitable for narrow buildings. The contrasting height of the openings (walls, sill, panels or furniture) ordered by the space also immediately influence the level and velocity of ventilation.