Experimental study of microclimate benefits following de-sealing and revegetation in a parking lot.

This study investigates the evolution of microclimatic benefits following de-sealing of a 64 m² patch (Oasis) inside a parking lot located in the suburbs of Angers, France. Vegetation (trees and herbaceous species) was introduced. We compared the microclimate in the Oasis with that of a neighboring asphalt area (negative control), a meadow area (positive control), and under a tree in a sealed area (Figure 1). This comparison was conducted using on-site meteorological stations. Over the two years following de-sealing, microclimate variables were monitored, and thermal comfort was evaluated using the Universal Thermal Climate Index (UTCI) as vegetation developed. The Oasis experienced a significant reduction in surface temperature compared to surrounding asphalted areas, with a maximum decrease of 18.4°C during the first summer and 23.0°C during the second one. This cooling effect was attributed to the development of the herbaceous layer, which covered 60% of the Oasis three months after sowing and exceeded 90% coverage from the second year. The reduction in surface temperature contributed to improved daytime thermal comfort. Tree shading further enhanced local cooling, reducing UTCI by up to 8°C in shaded areas. No evidence of lower nocturnal air temperature compared to sealed reference areas was observed, possibly due to the patch's small size and air mixing with the surroundings. This study highlights that small-scale de-sealing and revegetation initiatives can deliver notable microclimate benefits in urban environments from the first year, with even greater impacts as vegetation matures, supporting urban adaptation to climate change.