One of the Energy Policy objectives is the need to reduce energy consumption and emissions of greenhouse gases and transition to the use of energy, deriving from renewable sources. This thesis deals with the analysis of the Directive 2010/31/EU on the energy performance of buildings, pursuing its main objective, the nearly zero-energy building. Main part of the thesis includes an overview of the renewable energy sources and the analysis on improvement of energy efficiency of a specific building. I presented the renewable sources of energy, their potential applicability, their use in Republic of Slovenia and their strengths and defects. The principal problem regarding their extraction still lies in the high investment costs. When dealing with improvement of building energy efficiency, I firstly calculated the use of energy regarding the present state. The analysis of the present state showed that the use of heating energy is too high, thus I below presented and calculated possible measures for improvement of energy efficiency. I came to the conclusion that the main objective of the Directive 2010/31/EU, the nearly zero-energy building, can be met by a combination of improvement of building efficiency and generating the energy that is needed for operation of a building from renewable sources. Most attention will have to be paid to the remediation of the building sleeve, because this is the only way to reduce such specific transmission losses as well as the needed heating energy. This consumptions are thus reduced to such extent that the energy, needed for the operation of a nearly zero-energy building, is obtained from the renewable sources.