LAUSR

The mean radiant temperature (Tmrt) is the most important meteorological factor influencing human thermal comfort in urban areas. Numerous methods have been implemented for estimating Tmrt using measured radiometer or thermometer data, and exhibit different levels of accuracy. This study presents a simple technique based on the traditional method (Tmrt_TM) to estimate Tmrt by utilizing measured radiation data from the radiometers. The estimated Tmrt values from the six-directional method (Tmrt_SM) and two black globe thermometer methods (Tmrt_BG and Tmrt_BGv) at two stations (sky view factor 0.69 and 0.94) in Jeju, Republic of Korea, for 8 days (5 sunny days, 3 (semi-) cloudy days) in spring and summer were used to validate the Tmrt_TM. The results showed that the mean differences between Tmrt_TM and Tmrt_SM were within the required accuracy for comfort in ISO 7726 (± 2 ℃) on sunny days and were reduced to 0.1–0.3 ℃ in high Tmrt conditions such as clear summer days. The Tmrt_BG in most sunny and semi-cloudy days and Tmrt_BGv on all days resulted in large mean differences from the Tmrt_TM that exceeded the required accuracy for thermal stress in ISO 7726 (± 5 ℃). Therefore, both black globe thermometer methods should be used carefully when estimating Tmrt, especially during sunny days. The correlations between Tmrt_TM and Tmrt_SM were highly significant, 0.93 on all days (p = 0.01). The newly developed regression equations between Tmrt_TM and Tmrt_SM could reduce mean differences within 0.5 ℃ for all days, and their r2 values exceeded 0.87. Therefore, the simple Tmrt_TM technique can be used for Tmrt estimation in human thermal comfort studies.