Daily variation of ground radiation in unshaded and shaded environments and the effect on mean radiant temperature

Abstract

Ground radiation considerably affects the outdoor mean radiant temperature (MRT). However, ground radiation can vary significantly due to environmental and material differences, which still need to be studied more. Therefore, this study quantified the dynamic effect of ground radiations on outdoor MRT under unshaded and shaded environments for four common ground materials, namely, slabstone, asphalt, tile, and lawn. The fluctuations in ground radiation and the effects of ground radiation on MRT were examined from morning till evening. Changes in ground radiation and incident radiation were consistent in unshaded environments but occasionally inconsistent in shaded environments, and the changes in ground longwave radiation were relatively stable in both environments. In the four ground surfaces, approximately 50% of ground radiation (Rstr,g) was absorbed by the human body. Further, the mean maximum MRT change per hour caused by Rstr,g was 6.4 °C and within 2 °C in the unshaded and shaded environments, respectively. The findings provide a reference for microclimate optimization on ground.

Keywords

• Ground radiation
• Outdoor mean radiant temperature
• Outdoor thermal environment
• Thermal radiation
• Shaded environment