In recent years, the use of louvers as shading devices in office buildings has become a common standard. This usage has turned into a necessity due to climate change and the increasing need for energy conservation. Given that buildings account for a significant share of energy consumption and greenhouse gas emissions, optimizing the design of shading systems such as louvers can help improve energy efficiency and reduce energy costs. The performance of these louvers is highly dependent on their angle, which can be examined from various perspectives, including daylight, thermal loads, visual comfort, natural ventilation, and energy consumption. The aim of this research is to determine the optimal angle of external louvers in office buildings based on solar energy utilization and energy consumption levels. To achieve this goal, a sample building was designed and simulated with louvers installed on three facades: south, east, and west, in 17 different configurations. These simulations were conducted using DesignBuilder software in Tehran. The results of this study confirm the consistency with previous research and indicate that the optimal angle of louvers is climate-dependent. In all examined scenarios, the use of louvers resulted in a reduction of solar gain compared to buildings without louvers. The findings show that for low-rise office buildings in Tehran, the optimal louver angle is +70 degrees on the south facade, -40 degrees on the east facade, and +50 degrees on the west facade. Additionally, energy consumption in these optimal configurations decreased by between 4.9% and 29.28%.