This work presents an energy assessment of the natural ventilation performance within buildings located on both hot-temperate and mild-temperate conditions such as the existing along the central region of Mexico. With the assistance of a coupled thermalairflow simulation program, simulations are run without and with natural ventilation, respectively. Thereby, the consumption of air-conditioning presented in this region is validated with data from literature when natural ventilation is not applied. Results show that when natural ventilation is used thermal comfort is achieved more than 90% of the assessed time. Therefore, the cooling demand supplied by air-conditioning could be virtually avoided, especially when the building has high thermal capacity, feature presented on a great part of the building stock.