A study is conducted to optimize the geometry of a solar chimney equipped with a horizontal absorber in order to improve its performances in relation to the provision of ventilation. The problem is tackled through numerical solution of the governing equations for mass, momentum and energy in their complete three-dimensional and unsteady formulation. The numerical framework also includes a turbulence model (k-ε) and a radiant heat transfer (DO) model. Moreover, a Multi-Objective Genetic Algorithm (MOGA) is employed to derive the optimal configuration of the considered solar chimney. It is shown that an air velocity of 0.2 m/s can be obtained. This value is the minimum allowed air velocity according to the ASHRAE' s (American Society of Heating, Refrigerating and Air-Conditioning Engineers) adaptive comfort approach. KEYWORDSNatural ventilation; adaptative comfort; solar chimney; fluent; MOGA Nomenclature Greek letters Units absorptivity dissipation rate Reynolds stress tensor turbulence kinetic energy Density (Kg/m 3 ) Stepan's coefficient (W/m 2 /K 4 ) turbulent Prandtl numbers for k turbulent Prandtl numbers for e Thermal Expansion Coefficient (1/K)