Sustainable Decision-Making in Urban Design: Softscape Solutions for Mitigating Urban Heat Island Effects in Hot-Arid Climates

This paper examines the contribution of softscape elements to UHI mitigation in outdoor urban spaces, focusing on walkway treatments as an influencing factor on outdoor thermal comfort and microclimate conditions. Pedestrian paths represent an important area in cities and are often associated with the intensification of the UHI effect since they are directly exposed to sunlight and through the types of materials used in their construction. This study compares how three different softscape treatments would affect the thermal characteristics of such urban walkways. In each treatment, efficiency was analyzed regarding the lowering of surface and ambient temperatures within the context of UHI mitigation with the help of ENVI-met, a currently widely used simulation tool for microclimatic and environmental modeling in urban studies. These simulation results indicate that all three treatments reduced the temperature from the untreated base case; however, the one yielding the highest reduction in temperature became the most effective strategy to mitigate UHIin the current study. Although there was no statistically significant difference among the three softscape element types in their overall performance in mitigating the UHI effect, each of the treatments did result in a significant improvement in thermal conditions when compared to an untreated walkway. This result implies that any of these softscape elements could be introduced into the design of urban walkways for large benefits in the mitigation of urban heat, therefore allowing flexibility in urban planning and landscape design decisions for the improvement of outdoor thermal comfort and reduction of the UHI effect in city environments.