Greener & cooler. Thermal comfort as ecosystem service in the urban forest of Florence, Italy

Urban forests have a significant role on human health and well‐being. Good Health, according to WHO, is “a state of complete physical, social and mental well‐being”. An impressive number of studies have been conducted over the last two decades on the relationships between well‐being and trees. Surprisingly, one of the least approached subject concerns the relationship between trees and thermal comfort, i.e. “that condition of mind which expresses satisfaction with the thermal environment”. This condition is crucial in Mediterranean cities, where the climate connotes a prolonged exposure to potential heat stress during summer. Comfort depends on Environmental (air temperature, relative humidity, air velocity, radiant temperature) and Personal (body mass, psycho‐physical state, metabolic rate, activity) factors. The study focuses on how the urban forests of Florence are able to mitigate the summer heat stress, countering the effect of thermal discomfort, and how they represent comfortable places for the urban community. The study was carried out through microclimate measurements (weather stations and WBGT device) and coupled with structured interviews and on‐site observations and mapping of the activities of urban park users. The findings on the significant influences of microclimate parameters and personal factors on the participants’ perceptions of outdoor urban places are discussed. The weather data were processed through the application of bioclimatic indexes while the WBGT data were processed by DeltaLog10© software to check the heat stress thresholds according to clothing equipments and physical exercise. The results show that under tree cover the heat stress thresholds were not overtook ever while in full sun conditions severe or even dangerous discomfort values have been registered. The interviews highlighted that the thermal comfort was perceived as decisively higher under tree cover. The managed urban forests are felt as more comfortable and as areas where the well‐being is greater. The perception by the users of Florentine urban parks, is that the green areas are "relaxing" places, “cooler” when compared to the neighborhoods where they live. These results were confirmed by the observation and mapping of the activities carried out by the urban forests users even in the hottest days of the Mediterranean summer.