Solar chimney is a system to produce energy and it has several applications, such as production of electricity, buildings ventilation, heating and cooling. In this paper, a numerical investigation on a prototypal solar chimney system integrated in a south facade of a building is presented. The chimney is 4.0 m high, 1.5 m wide whereas the thickness at the inlet the channel has a gap equal to 0.34 m and at the outlet it is 0.20 m. The chimney consists of a converging channel with one vertical wall and one inclined of 2°. The analysis is carried out on a three-dimensional model in airflow and the governing equations are given in terms of k-ε turbulence model. The problem is solved by means of the commercial code Ansys-Fluent. Simulations are carried out considering the solar irradiance for assigned geographical location and for a daily distribution. Further, comparison between steady state and transient regimes is examined and discussed. Results are given in terms of wall temperature distributions, air velocity and temperature fields and transversal profiles. Performances are better when heat flux is higher and sun is in front of chimney and a low-emissivity glass improves solar chimney achievements. Analysis in transient regimes confirm results obtained in steady state regime.