The applications of AC unit for heating purposes increase with the improvements in air conditioners’ (AC) automation, performance, and production lines. Besides the developments in technology, heating applications of AC units can be a sustainable and effective solution with the aim of reducing CO2 emissions. In this study, heating costs of a simple dwelling were calculated. Three cities that represent three different climates in Turkey were chosen. Unlike steady-state equations to determine heating loads, transient heat conduction in wall and window components were solved by applying the finite difference method. Temperature deviation in wall and window materials among to thickness direction was calculated. Thus more accurate heating loads were obtained. In order to get realistic results, actual energy prices were used in cost calculations. Heating costs of AC unit that electricity is the only expense were compared with a natural gas burner. It is found that the AC unit is more economical than a gas burner in warm climate region because COP values of AC unit are the parameter that determines the electricity cost. COP in warm climate locations is much higher than that of cold climate region. In regards to heating costs, outside temperature and wind speed characteristics of a place where a building will be constructed should be well-known in order to choose the proper heating system.