Sidewalk landscape structure to enhance pedestrian thermal comfort in Kathmandu Metropolitan City

Abstract

The thermal comfort of pedestrians in the outdoor spaces of urban areas has deteriorated due to the urban densification. Street being major outdoor space that can promote physical activity, and especially with the emerging concept of walkable cities, thermal comfort in streets should be given utmost importance. Thermal comfort for pedestrians is the absence of any sense of discomfort when interacting with the outdoor thermal environment. This study aims to evaluate the effectiveness of various landscape measures to enhance pedestrian thermal comfort. The study adopted the quantitative approach and used the simulation and questionaire survey as methodological tools to mmet its objectives. The study was conducted on both sidewalks of Durbarmarg, one of the dense and busy streets of Kathmandu. The microclimatic modeling software ENVI-met 5.03 was used to create different interventions in landscape (trees and pavement) to see its effect on the thermal environment of sidewalks. The results of the simulation showed that increasing the leaf area density, tree canopy size and height can reduce the air temperature by 0.2 °C and Mean radiant temperature by 4.86 °C. Among the various pavement materials in various scenarios for the simulation, the light concrete pavement showed the highest decrease in terms of the air temperature (0.579 °C) however the mean radiant temperature was highest (7.22°C) for the same material. Hence, for the high reflective surfaces, the surface /air temperature is reduced but it increases the mean radiant temperature and hence might not be appropriate for the thermal comfort of the pedestrians.