Impact of well-watered trees on the microclimate inside a canyon street scale model in outdoor environment

Cities experience overheating due to factors such as urban form and materials, concentration of human activities, reduction in the amount of vegetation and water surfaces. Vegetation is one of the ways to reduce temperature peaks in the city during heat waves. The objectives of this paper are twofold: first, to study the impact on the microclimate of a north-south oriented canyon street at reduced-scale (1/5), then to study the impact of well-watered trees on the street microclimate. This study provides a highly integrated view of climatic mechanisms through the measurement of a set variables, including air temperature, relative humidity, wall temperature, conductive and radiation fluxes as well as tree transpiration and thus allows a better understanding of the physical phenomena at stake. It shows that the canyon street created an urban overheating of up to 2.8 degrees C during the night, and up to 2.4 degrees C during the day, and that trees reduced the air temperature in the street by up to 2.7 degrees C during the day. Finally, trees improved human thermal comfort with a reduction of 8 degrees C of the Universal Thermal Climate Index at midday.

Automated summary

Cities experience overheating due to factors such as urban form, concentration of human activities, and reduction in vegetation and water surfaces. Vegetation is effective in reducing temperature peaks during heat waves. This study provides insights into the impact of urban morphology on microclimate and the cooling effects of well-watered trees in urban areas.