Due to new policies for energy efficiency, buildings are having new thermal insulation thickness to achieve desired U-factor and energy class in energy passport. Before, the thermal insulation of the houses was 5cm thick, but nowadays with new policy it needs to have higher thickness. This influences an increased cost of the house in its building phase, but actually saves money over time during years. In this paper one common Serbian house is modeled in Energy Plus and then the thermal insulation thickness is changed. Also influence of the house orientation is discussed. Afterward, energy consumption for these houses is compared for old, refurbished and the house achieving new standard, and economic savings during the years and payback period are discussed. Results show that there is big influence of the thickness of the thermal insulation, but also that it is better to have the house oriented toward south to increase heat gains from solar energy during winter.