The main purpose of jali is to control light, air flow, visual privacy, aesthetic and social role, and spatiality. The central technical aspect of the jali's construction is its function as a climate-controlling element, where the distances between the interstices, the size, and the volume of the balusters all have a direct effect on glare, temperature, humidity, and airflow inside the structure (Fathy, 1986).
Source: wiktionary