The paper presents a method of calculating the payback period of energy-saving measures. The described measures are aimed at improving the thermal protection of the external walling maintained buildings withthermal insulation products (stone wool synthetic binder). Examples of calculation for simple payback of additional thermal insulation of external walls of buildings are provided. The authors also present examples of calculations for payback calculated taking into account the growth of tariffs for heat energy. Selected objects of study are panel tenement apartment building, as well as single-family residential stone house. The above mentioned calculations are made for climate conditions of St. Petersburg region and Leningrad Region.