The purpose of the conducted research was to assess the economic efficiency of the application of heat pumps in heating. The research was carried out in the Ruda-Huta Commune (Chełm County, Lublin Province). The research was conducted at the School Complex, where, in 2012, the heating system was changed from a system powered by fuel oil to a system of ground heat pumps. Due to the very low level of interest rates during the analysed years, the method of simple payback time, SPBT, was used to assess the economic effectiveness of this investment. The research shows that the application of a ground-source heat pump for heating the building of the School Complex in Ruda-Huta was economically efficient in comparison with the oil fuel system. The SPBT simple payback time was 2.14 years. Obtaining such a quick return on capital expenditure was a result of both significantly lower operating costs and obtained subsidy in the amount of approximately 50% of the total financial resources spent on the implementation of this project. Based on the obtained results, it can be concluded that the replacement of the oil heating system with heat pumps would be economically viable even without subsidies, but then the SPBT would extend to 5.48 years.