Clothing radiative properties and outdoor thermal comfort in summer: A comparative assessment of Chinese cities using MRT and PET

Clothing radiative properties—solar reflectivity ( ρ sr ) and longwave emissivity ( ε lr )—fundamentally influence thermal comfort in outdoor environments during summer. This study simulated the effect of three clothing fabrics with different radiative properties, namely ordinary yellow fabric (OYF: ρ sr = 0.67, ε lr = 0.89), ordinary white fabric (OWF: ρ sr = 0.79, ε lr = 0.91), and radiative cooling fabric (RCF: ρ sr = 0.98, ε lr = 0.96), on summer outdoor thermal comfort across 34 major Chinese cities during August 2024 using modified calculation methods for mean radiant temperature (MRT) and physiological equivalent temperature (PET). Results demonstrated significant thermal comfort improvements with higher solar reflectivity and longwave emissivity: MRT values decreased from 49.0 °C (low reflectivity: OYF) to 42.4 °C (moderate reflectivity: OWF) and 31.4 °C (RCF: high reflectivity and emissivity), and PET improved from 35.2 °C (OYF) to 32.3 °C (OWF) and 28.9 °C (RCF). The proportion of PET values within the slightly cool to slightly warm range increased from 19.8% (OYF) to 29.1% (OWF) and 40.5% (RCF), and the combined proportion of hot and very hot conditions decreased from 56.6% to 9.6%. Correlation and regression analyses indicated that the difference between the MRT for OYF and RCF was primarily driven by global solar radiation and that for PET reflected the combined effects of solar radiation, ground surface temperature, and relative humidity. These findings provide quantitative guidance for fabric selection under diverse summer climatic conditions.