This document discusses natural ventilation and factors that affect air flow in and around buildings. It covers topics like the functions of natural ventilation including supplying fresh air and removing contaminants. Thermal stack effect and convective cooling are natural ventilation methods driven by temperature differences. Wind flow patterns are impacted by various building configurations and elements like wing walls, chimneys and wind catchers. Factors that influence indoor air flow include window openings, atria, and wind speed and direction.