This paper presents an extensive study aimed at assessing the impact of the most typical thermal bridges on the building energy performance of a typical Italian building stock. According to a recent European project (TABULA) the most typical Italian building types (terraced house, multi-family house and apartment block) are analyzed. Moreover, different thermal insulation levels of the envelope are considered. For each building type and envelope solution, the most common thermal bridges are considered and the related linear thermal transmittance is calculated through a finite different calculation method according to EN ISO 10211. The building energy performance is then calculated through the monthly steady-state method specified by EN ISO 13790. In order to perform a sensitivity analysis, a significant and representative number of cases are generated, using a sampling technique