According to EN ISO 7730 the estimation of RTA (trA-trB) is prescribed; it has been measured by Indoor Climate Analyzer of Bruel and Kjaer. It was proved that a new instrument, globe stereothermometer, developed in Malý´s research group, can be applied for this purpose.It is a globe of 15cm in diameter divided into 6 segments; the surface temperature of each segment is called stereotemperature (tstereo). The mean value of all six stereotemperatures equals to globe temperature (tg). Radiant Temperature Asymmetry can be estimated from equations (6),(7)and (8) and from Fig. 7.Stereothermometer is produced by SIPOCH Ltd. Prague. The company also developed electronics and technology of the instrument (dipl. Ing. L. Vajner). This paper introduces new method for radiant temperature asymmetry estimation.