Energy conservation in buildings open doors for innovative techniques for thermal comfort. Recently, Simulation of smart building energy management (SBEM) has gained attention for energy conservation and efficient utilization in buildings. In this study, we proposed a conceptual framework to achieve thermal comfort inside a low-energy smart building (LESB) with real-time environmental conditions by computational fluid dynamics (CFD) simulation. CFD simulations are performed in natural ventilation mode at five different time periods to understand the climatic conditions inside the LESB in summer solstice. Heat energy entering the room at noon is effectively blocked by a special air layer of the roof. In summer, comfort inside the LESB is limited in natural ventilation mode. So, the indoor thermal comfort can be maintained with air conditioners (AC). In this study, predicted mean vote (PMV) is adopted to predict the thermal comfort with different AC position inside the LESB for energy conservation. AC installation away from the center of the wall avoids short circulation and the air flows to farther distance. The farther air flow helps to maintain uniform temperature inside room. This work helps in understanding the parameters to be considered in designing an LESB with good thermal comfort.