Estimating outdoor mean radiant temperature in a humid subtropical climate

• Published in: Building and environment 2020-03, Vol.171, p.106658, Article 106658
• Main Authors: Manavvi, S., Rajasekar, E.
• Format: Article
• Language: English
• Subjects: Biometeorology; Climate; Coefficients; Convection; Convection coefficient of gray globe thermometer; Humid climates; Open spaces; Radiant flux; Short-wave and long-wave radiant flux densities; Statistical analysis; Temperature; Thermal comfort; Tmrt; Urban environment
• ISSN: 0360-1323; 1873-684X
• DOI: 10.1016/j.buildenv.2020.106658

Mean Radiant Temperature (Tmrt) is a decisive parameter in determining outdoor thermal comfort in human biometeorology. The estimation of Tmrt in an outdoor environment is however complex. This study attempts to determine Tmrt by the six directional method and recalibrate the mean convection coefficient of the gray globe for ease of use in the humid subtropical climate. Six directional short - wave and long-wave radiant flux densities have been measured and analysed across different urban open spaces — plaza, promenade and green. The study presents the relationship between Tmrt and the radiant flux densities. Tmrt values obtained via the six directional method show a statistically significant difference with those obtained using mean convection coefficients discussed in literature. Consequently, the mean convection coefficient of the gray globe thermometer has been recalibrated for use in the humid subtropical climate. Tmrt estimated via the recalibrated mean convection coefficient agrees well with the results of the six directional method. •This study evaluates short-wave and long - wave radiant flux densities in varied typologies of open spaces in the context of humid subtropical climate.•Computing Tmrt in accordance with ISO 7726:1998 has been found to be inappropriate for use in the context of outdoor spaces in humid subtropical climate.•The mean convection coefficient of the gray globe thermometer has been re-calibrated for use in humid subtropical climate and results validated through field measurements.•An increment of 1 K in Tmrt in the open spaces can be attributed to an increase of 8.33 Wm-2 in the weighted sum of long-wave or short-wave radiant flux densities.