Many pavements contribute to the urban heat island (UHI) effect due to their bulk mass and heat absorption capacities. Granular ground surfaces composed of soils or sands do not contribute to the UHI effect in a similar manner. Their porous nature may lessen the effect both with an increased insulating capacity and with an enhanced mechanism for evaporative cooling from absorbed water.
Pervious concrete is a novel pavement which is being developed to aid in preventing stormwater related environmental problems. Pervious concrete has a network of interconnected voids which allow water exfiltration to the subbase below. Limited studies on pervious concrete indicate that the pervious concrete surface can have elevated temperatures as compared to similar traditional impervious pavements, but that temperatures are lower under the pavements.
This study focuses on a site in Iowa where both a pervious concrete and a traditional concrete paving system have been installed and temperatures recorded within the systems for extended time periods. The analyses cover days with negligible antecedent precipitation and high air temperatures, extreme conditions for UHI impacts. This paper compares the increase in overall heat stored during several diurnal heating cycles in both of these systems. These analyses include not only the temperatures at various depths, but also the heat stored based on the bulk mass of the various layers in each system and below grade. Results suggest that pervious concrete pavement systems store less energy than traditional systems and can help mitigate the urban heat island.
Haselbach, Liv, Kevern, John, Schaefer, Vernon. 2009. Hot Weather Comparative Heat Balances in Pervious Concrete and Impervious Concrete Pavement Systems. Presented to the 2nd International Conference on Countermeasures to Urban Heat Islands. September 19-23, 2009.
John Kevern (University of Missouri-Kansas City)
Vernon Schaefer (Iowa State University)
Publication Date: September 2009