ENThe article addresses the topical problem of the construction sector: improving the energy efficiency of buildings. Purpose of the article: after analysing the theoretical and documentary assumptions of increasing the energy efficiency of the construction sector, to form and substantiate the possibilities for increasing the energy efficiency of buildings in Lithuania. The article analyses the content of scientific literature and documents on the energy efficiency of buildings, summarises the statements of the performed empirical research – interviews of seven experts. The analysis of the scientific literature enabled us to briefly formulate the concept of energy efficient building. The analysis of the content of the documents showed the situation of Lithuanian buildings in the field of energy and the envisaged state plans for increasing the energy efficiency of existing buildings. The suggestions made during the expert interview can be useful for improving the energy efficiency of buildings. Key words: construction sector, building, energy efficiency, renewable energy sources. [From the publication]