Residential buildings account for a large proportion of global energy consumption in both low- and high-income countries. This consumption creates a great burden on energy security as it is not proportional to the produced energy. Efficient planning to meet building energy needs requires accurate, high spatial resolution information on energy consumption. To justify the high energy consumption, this study focuses on evaluating the thermal performance of existing residential buildings. This evaluation was done using building performance simulation tools. The paper's research methodology follows the experimental approach. This approach utilizes energy simulation to evaluate the existing residential building's thermal performance. The evaluation is done by analyzing thermal comfort levels according to the acceptable ranges stated by the Housing and Building National Research Center. Residential buildings are built without taking appropriate design measures to protect the indoor environment from external weather conditions. researchs' importance is to study how this will affect indoor thermal comfort. The paper aim at finding the main reason for high levels of energy consumption in the residential sector.