In this study, the turbulent flow of exhaust gases through the stack has been modeled. Velocity and temperature profiles boil; in the stack and the plume are obtained from the developed model and the flows are also analyzed from the exergetic point of view. A typical thermal energy system of 170 kW heating capacity has been chosen and fuel-oil of medium sulphur contents and natural gas are investigated. Empirical parameters of the model determined via a thorough literature survey and wind effects are included in the study. The applied model is found to be a good tool for the correlation of the stack parameters with pollutant dispersions under given meteorological conditions. In the end, however, overall air-pollution will be a strong function of effective fuel utilization.