Newly opened residential buildings in Libya consume enormous amounts of electricity to operate mechanical air conditioning systems due to their poor thermal performance and declining indoor environmental quality, which aligns with rising carbon emissions and the greenhouse effect. This study aims to evaluate and improve the thermal performance of an existing residential building in Libya to reduce energy consumption and achieve sustainable thermal comfort through bioclimatic design strategies. The study employed a hybrid methodology combining on-site measurement and digital analysis. The first step involved detailed field monitoring of the building's indoor environmental parameters, followed by the creation of a computer simulation model using EnergyPlus software (integrated via the DesignBuilder interface) to calibrate the model and implement a range of architectural intervention strategies (orientation modification, thermal envelope optimization, and the application of shading and natural ventilation techniques). The simulation results showed that implementing the proposed bioclimatic strategies led to a 30% reduction in overall air conditioning energy consumption. [%], with a reduction in maximum indoor temperatures of [4.2°C] during the summer months, resulting in a [70%] improvement in acceptable thermal comfort hours without the need for mechanical cooling. These results underscore the impact of architectural improvements in guiding urban planning policies towards low-carbon residential buildings in hot and arid regions.................. ......................... Keywords:............. Poor indoor quality - Building orientation - Building energy control and consumption - Energy saving in buildings.