The thesis includes carrying out an analysis of the impact of thermal bridges on buildings heating energy consumption through the use of software, based on standard SIST EN ISO 13790. Within the framework of this thesis the quantitative impact of specific thermal bridges and quantification of their effects on building’s heating energy consumption is determined. The comparison is carried out in a specific case, the selected multi-storey office building. The methods for the determination of thermal bridges in the building envelope are based on the standard SIST EN ISO 14683. Numerical simulations of thermal bridges are carried out in computer program Unorm and the buildings heating energy consumption is calculated using TOST program.