Modeling the performance of cool pavements and the effect of their aging on outdoor surface and air temperatures

Aiming at the improvement of a dense urban area's microclimatic conditions, this study examines by simulation means, the application of highly reflective materials as a mitigation strategy. However, as significant albedo changes may occur due to weathering and aging, the study investigates the surface (Tsurf) and air (Tair) temperature cooling potential of cool paving materials, both for the design and the aged values of solar reflectance; the aged albedo values are issued from previously reported experimental campaigns. Since the majority of the existing studies evaluate the cool materials' impact at the pedestrian's height, the current work aims to provide further insight on the vertical profile of the achieved Tair reduction due to cool pavements, at different heights of the study area's canyons. The analysis revealed that the Tsurf and Tair decrease due to cool pavements is reduced by 50%, when the aged albedo values are considered, while the obtained Tair reduction is negatively related to the distance from the ground. The accurate assessment of the high albedo materials' effect on the urban microclimate imposes thus the consideration of the albedo degradation due to weathering and aging whereas extra effort should be given on the development of cold materials standing the test of time.