Abstract Nowadays, several regulations exist covering different general guidelines that must be considered in order to decrease the energy demand in residential buildings. One of the main ones consists in increasing the insulation of the building envelope with the aim of minimizing heat losses or gains. As a result, a proper treatment of thermal bridges and their in situ construction becomes more relevant because their relative effect on the overall thermal demand of the building increases. Nevertheless, there is still a great uncertainty about the dynamic behavior of thermal bridges and few energy simulation programs allow implementing them considering their thermal inertia. To obtain more information about the thermal response of thermal bridges, a series of tests have been carried out in a guarded hot box testing facility. The characteristics of a pillar thermal bridge have been studied in both steady and dynamic regime, being one of the main objectives of this study the determination of the area of influence of a thermal bridge. For this purpose, test results are compared with simulation ones.