Recently, a numerous number of houses has been built using AAC materials, which consume the most amount of energy in the building sector by Heating, ventilation, and air -conditioning (HVAC) systems. Thus, the most significant factor affecting the energy consumed by HVAC systems is the materials used in the building. Building models are important tools in determining the energy efficiency of buildings. Numerous strategies have been established to construct building models, such as the weight, gray, and black boxes, as well as hybrid models. Hybrid models have not been researched extensively, although they provide a reasonable representation of actual indoor conditions. Therefore, this study employs a hybrid calculation model for the analysis of physical and empirical correlations to evaluate thermal comfort in buildings, which reflects their energy consumption. The residential load factor (RLF) technique is adopted owing to its systematic organization and ease of use, which is achieved by dividing the model into submodels. The model is verified and validated by drawing a comparison with field measurements and the output obtained from ANSYS software. The actual field measurements and ANSYS outputs match the outputs of the proposed model; the results show small residual errors, indicating a well-defined model structure. The cost and energy savings of vernacular buildings and autoclaved aerated concrete (AAC) (or low-cost) buildings have been highly debated in Basra city. Models of these two different building materials are simulated within the MATLAB/Simulink environment. Their results indicate that the vernacular building has the highest energy saving potential up to 47.83% over 24 h a day. These results provide an excellent argument to realize the benefits of vernacular buildings by reducing the dependency on powered cooling.