If the windows on both sides of the buildings are opened, the overpressure on the side facing the wind, and/or low pressure on the adjacent protected side, will make a current of air through the room from the uncovered side towards the sheltered side. If there are windows on both sides in a building, cross ventilation is appropriate where the width of the room is up to five times the floor-to-ceiling height. If openings are only one side then wind-driven ventilation is more suited for structures where the width is around 2.5 times the floor to ceiling height.