Thermal bridges tend to increase overall buildings energy demand and might cause water condensation problems. They are thermally characterized by a linear transmission coefficient $\psi$ or a point transmission coefficient $\chi$. Today, most studies of thermal bridges are based on theoretical or numerical calculations. Standardized methods define default values and assumptions to make in simple or detailed simulations. The few existing in situ characterization methods of thermal bridges are based on steady-state assumptions. This makes them highly sensitive to weather conditions and often requires very long measurements. The present paper proposes a novel active method for the in situ characterization of a thermal bridge. It generalizes a measurement of a homogeneous wall thermal resistance. The indoor air is rapidly heated for a few hours (typically 6) and the wall thermal response is analyzed with an inverse technique based on a white-box model. Surface temperatures and heat fluxes are measured with contact sensors on a sound area and these quantities are then extrapolated to nearby thermal bridges using infrared thermography. The total heat transfer coefficient, required in the heat flux extrapolation process, is monitored with a specific device. The method is validated on a full-size load-bearing wall built inside a climate chamber. The mechanical supports, holding the internal insulation system implemented on the wall, generate several thermal bridges. The $\psi$-values estimated by the active method are less than 20% away from steady-state measurements taken as reference. Many configurations were tested with constant and varying external temperature and the method proved its robustness to these unsteady conditions.

热桥往往会增加建筑物的整体能源需求，并可能导致水凝结问题。它们具有线性传递系数的热特性$\psi$ 或点传输系数 $\chi$。如今，大多数热桥研究都是基于理论或数值计算的。标准化方法定义默认值和假设，以进行简单或详细的仿真。现有的几种热桥原位表征方法均基于稳态假设。这使得它们对天气条件高度敏感，并且通常需要非常长的测量时间。本文提出了一种新的原位主动方法热桥的特性。它概括了均质壁热阻的测量。快速加热室内空气几个小时（通常为6小时），并使用基于白盒模型的逆向技术分析壁的热响应。使用接触传感器在声音区域测量表面温度和热通量，然后使用红外热成像将这些量外推到附近的热桥。用特定设备监控热通量外推过程中所需的总传热系数。该方法在气候室内部建造的全尺寸承重墙上得到了验证。机械支架支撑着安装在墙壁上的内部隔热系统，产生了多个热桥。的$\psi$用主动法估算的-值与作为参考的稳态测量值相距不到20％。在恒定和变化的外部温度下测试了许多配置，该方法证明了其在这些不稳定条件下的鲁棒性。