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Experimental Study the Albedo of Urban Canyon Prototype with Reflective Pavements (Streets)

Yinghong Qin, Jia Liang, Kanghao Tan, Fanghua Li


Urban structures consist of buildings, roofs, walls and streets. Buildings at both sides of the street create a canyon-like environment that is called urban canyon (UC). In a UC, conventional impervious pavements absorb and store solar radiation but negate the evaporative cooling, contributing to the development of urban heat island (UHI). One popular option to mitigate UHI is to make the pavements more reflective than conventional pavements and to absorb less solar radiation in the urban area. However, it remains unknown if a reflective pavement in an urban canyon can effectively reduce the solar absorption of the urban surfaces. This study prepares ten UC prototypes with differential pavement reflectivity and with south-north orientation, west-east orientation, and cross-street orientation, respectively. The albedo of these UC prototypes is measured by a new method that is proposed to estimate the reflectivity of urban canyon prototypes. It is found that raising the albedo of the pavement is inefficient to increase the albedo of the UC, especially for UC with great aspect ratio. In low aspect-ratio UC or parking lot, reflective pavements reflect a sizable additional diffuse radiation to pedestrians. Therefore, it should be caution to develop reflective pavements as urban cooling strategy.


Multiple reflections; Urban heat island; Albedo; Reflectivity; Diffuse radiation

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DOI: http://dx.doi.org/10.18686/ag.v3i1.1134