ABSTRACT: The thermal comfort and air quality inside buildings spaces is much recommended in Nowadays for human’s health and environment protection, especially if the inside comfort conditions are assured by passive systems means. In hot dry climate such Laghouat city in the south of Algeria, the first consideration in architecture design is given to the building envelope referring to the vernacular architecture in the region. The buildings with high thermal inertia envelope ensure the inside thermal comfort while it is properly closed during day time when the outside air temperature is very