Mitigation urban heat island by using porous and permeable block pavement

Local climate change has intensified extreme events such as the Urban Heat Island (UHI) effect, where urban areas experience higher temperatures than nearby rural zones, primarily due to the prevalence of heat-retaining materials and reduced vegetation. This creates challenges for sustainability, health, and energy use. A key mitigation method is the use of porous and permeable pavements, which enhance surface reflectivity, promote cooling through evaporation, and limit heat storage. This study examines the performance of permeable and porous block pavements for outdoor urban applications. Field and lab measurements and ENVI-met simulations were conducted to assess various pavement types implemented in mainland Venice. Experimental tests focused on three samples-a standard block and two porous variants (dark and light-coloured) were developed to characterize the thermal properties (thermal conductivity, thermal diffusivity, solar absorptance, emissivity, and solar reflectance index) and to determine the changes in thermal fluxes during the monitoring period. The experimental test shows how the porous light-coloured material has proved as most effective in mitigating UHI, able to reduce the average external surface temperature of by 1.5-2 degrees C in the afternoon in respect to the standard block; while dark porous block, even if made by the same porous material composition of light coloured, it is not always effective in improving the application due to the different albedo. The results of the simulations are comparable to those characterised in the laboratory, with similar daily mean (almost 32 degrees C) and maximum (38 degrees C) temperatures in the receptor at the same sample location, although the daily trend is closer to that of the outdoor air. The adoption of permeable paving blocks offers significant environmental and urban planning benefits, such as an improvement of stormwater management, thermal comfort, public health, urban liveability. Their integration into urban design could support climate resilience according to sustainability policies.