Influence of the building enclosed forms on thermal contribution of retro -reflective and high-reflective coatings

There are more high-density urban spaces and their forms prominently affect the regional thermal environment, especially for the spatial distribution of solar thermal radiation. Under this condition, the contribution efficiency of reflective coatings should be reevaluated to improve the regional thermal environment. Three typical forms of high-density buildings, namely the Determinant Form ( d -Form), Three-Sided Enclosed Form (TSE-Form) and Four-Sided Enclosed Form (FSE-Form), were proposed. High-reflective coatings (HR-coatings) and retro -reflective coatings (RR-coatings) were employed with the different reflective mechanisms, while the albedo, wall temperature, and air temperature were monitored. Experimental results showed that the higher the enclosed degree of buildings covered by HR-coatings, the poorer the regional thermal environment and the higher the heat island efficiency. However, the opposite was true in enclosed buildings with RR-coatings. RR-coatings had a better thermal contribution than HR-coatings, and the higher the enclosure degree of buildings, the higher the improvement efficiency of RR-coatings. Compared with HR-coatings, RR-coatings increased the maximum and average regional albedos by 0.67 %∼3.42 % and 1.36 %∼5.59 %, respectively, and lowered the maximum and average temperatures by 0.26 °C∼7.05 °C and 0.02 °C∼4.83 °C for model walls and 0.59 °C∼4.41 °C and 1.80 °C∼3.06 °C for outdoor air, respectively.