A simple technique for the traditional method to estimate mean radiant temperature

Area of Science:

• Environmental Science
• Urban Climatology
• Human Thermal Comfort

Background:

• Mean radiant temperature (T_mrt) is crucial for human thermal comfort in urban environments.
• Existing T_mrt estimation methods vary in accuracy, necessitating simpler, reliable techniques.
• Accurate T_mrt assessment is vital for understanding and improving urban thermal conditions.

Purpose of the Study:

• To present and validate a simple technique for estimating mean radiant temperature (T_mrt) based on the traditional method (T_{mrt_TM}).
• To compare the accuracy of T_{mrt_TM} against the six-directional method (T_{mrt_SM}) and black globe thermometer methods (T_{mrt_BG}, T_{mrt_BGv}).
• To develop regression equations to enhance the accuracy of the T_{mrt_TM} method.

Main Methods:

• Utilized measured radiation data from radiometers to estimate T_mrt using the traditional method (T_{mrt_TM}).
• Validated T_{mrt_TM} against T_{mrt_SM}, T_{mrt_BG}, and T_{mrt_BGv} at two urban stations in Jeju, Republic of Korea.
• Collected data over 8 days during spring and summer, encompassing sunny and cloudy conditions.

Main Results:

• T_{mrt_TM} showed mean differences within ISO 7726 comfort accuracy (±2 ℃) on sunny days, improving to 0.1-0.3 ℃ in high T_mrt conditions.
• Black globe thermometer methods (T_{mrt_BG} and T_{mrt_BGv}) exhibited larger deviations, exceeding thermal stress accuracy limits (±5 ℃).
• Highly significant correlations (r=0.93) were found between T_{mrt_TM} and T_{mrt_SM}; developed regression equations reduced mean differences to <0.5 ℃ with r² >0.87.

Conclusions:

• The simple T_{mrt_TM} technique is accurate and reliable for estimating mean radiant temperature in human thermal comfort studies.
• Black globe thermometer methods require careful application, particularly on sunny days, due to potential inaccuracies.
• Refined T_{mrt_TM} using regression equations offers a precise and practical approach for urban thermal environment assessments.