Today's urban areas are filled with tall buildings that require significant energy. To enable the implementation of small-scale wind turbines for dispersed electricity generation in cities, it is crucial to evaluate their performance in close proximity to buildings. This study aims to assess the performance of conventional Savonius rotors near a circular cross-sectional building for the first time. The performance of a Savonius wind rotor is being studied at different installation angles (30°, 45°, 60°, and 90°) with a constant non-dimensional gap space (S/D) of 2.0 between the rotor center and building envelope under a constant free-wind speed of 6 m/s. Two possible wind rotor rotation scenarios, inward and outward, are thoroughly tested and studied. Computations are carried out for tip speed ratios (TSR) of 0.4, 0.8, and 1.2. The obtained results are successfully validated for both the Savonius rotor in the free-wind flow (without a building) and a circular cross-sectional building (without a wind rotor) as well. The results show that installing a Savonius rotor at angles of 60° and 90° provides the maximum power coefficient based on the TSR. In contrast, placing the rotor at 30° reduces its performance even more than the reference case. For optimal rotor angles, inward rotation is preferred over outward rotation regardless of the TSR. Finally, there are improvements of 208.72 %–439.95 % compared to the reference case for 60° and 90° under inward rotation.