Sensible heat discharging from pavements with varying thermophysical properties

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© 2018 Elsevier Ltd A large portion of the solar absorption of traditional pavements is discharged as sensible heat to the above air and contributes to the formation of urban heat island. The amount of the sensible heat depends on pavement surface-layer thermophysical properties including thermal conductivity, density, heat capacity, surface's emissivity, and albedo. To sort out the influences of these factors in order, this study develops a new simplified theoretical formula to estimate the instantaneous sensible heat flux and the daily accumulative sensible heat from pavements with varying thermal properties. Both the theoretical formula and the numerical results reveal that raising the thermal conductivity, density, or heat capacity of the pavement or increasing them simultaneously decreases the sensible heat but the decreasing rate is negligibly small compared to the amount of the sensible heat. A greater amount of pavement-rejecting sensible heat could be reduced by increasing the surface-layer emissivity. But most traditional pavements have a high emissivity of 0.80–0.95 already so there is a tiny space to vary the pavement's emissivity for curbing the sensible heat. The most effective way to curtailing the pavement-rejected sensible heat is to make the pavement surface highly reflective.

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Sustainable Cities and Society