According to the literature, both advanced and developing countries are facing several challenges due to the lack of clean energy and emissions of CO2 leading to climate change. Especially in the built environment, energy efficient buildings are highly desirable to save energy without affecting occupant’s health while providing an acceptable indoor environment and thermal conditions. The use of insulation, passive solar heating, and HVAC systems can contribute to improve the indoor thermal comfort. In the present study, a numerical simulation model is developed to evaluate the human comfort factors in a simulated indoor environment. The CFD model considers the thermal interaction of humans with the indoor environment. Ventilation and a heat source are added to model a workspace for evaluating indoor air temperature and human comfort factors. Indices like predicted mean vote (PMV) and predicted percentage dissatisfaction (PPD) are evaluated to assess thermal sensation of human body when adding and removing a heat source in the model office (i.e. radiator).