The thesis presents the production of the measured and the calculated energy performance certificate, which is as of late mandatory when selling or renting buildings, as well as with building as a part of the project of Works executed. The performance certificate has been executed for the two buildings which were built as parts of the development control centre of the company Krka, d. d., Novo mesto. The buildings show similarities in design and purpose. The first part of the thesis presents the relevance of the energy performance certificate and the legislation, which provides a detailed definition of the production of the energy performance certificate. The following part is the presentation of the buildings in reference to their architectural building construction and geographical location. The first part of the analysis presents the production of the measured certificate, which is executed according to the acquired measured data about the monthly energy consumption. The second part of the analysis offers insight into the methodology for the calculation of the energy features and the production of the energy performance certificate using the TOST program. As part of the analysis, the calculation of the energy needed for the functioning of the building and yearly emission of the CO2 is executed. The comparison of the measured and the calculated values, dealt with next, poses the question whether it is relevant to compare of the two certificates. The factors causing the discrepancy are hereby discussed. Recommendations for the energy renovation are presented in the final part of the analysis. The restoration measures which would result in the reduction of energy consumption are substantiated by calculated simulations in the TOST program. The thesis finishes with findings and conclusions arrived at throughout the entire research.