The temperature of the black globe is an important variable in the calculation of microclimatic indices; represents the integrated effects of thermal radiation (radiant heat), air temperature and air speed on human comfort. Sensor designed to measure the radiant temperature according to ISO7726 is made of opaque black copper (reflection <2% ASTM 97-55). If connected to the LSI Lastem M-Log and R-Log series data loggers with the wet bulb temperature sensor, it allows the calculation of the WBGT thermal stress index.