S07 - Session P1 - How are green spaces effective in urban heat island mitigation? A case study in North-eastern Italy

Authors: Lucia Bortolini *, Paolo Semenzato, Valentina Brasola

The urban heat island (UHI) is an important and current issue of most urbanized cities. Although it is more evident in the winter season and during the night, it becomes particularly critical in the summer season in conjunction with anticyclonic heat waves. In such circumstances, it can be particularly harmful to human health and there are numerous studies that link mortality and morbidity with extreme thermal events. The use of vegetation, and in particular urban tree planting, constitutes one of the most effective strategies in contrasting the heat island effects. In order to analyze the mitigation effects produced by green spaces in the city centre of Padua, a municipality in the North-East of Italy, simulations of the air temperature trends and their special distribution were carried out using i-Tree CoolAir model. The extreme conditions for maximum summer temperatures were considered, a situation in which the UHI effects become more critical. A particularly hot July day was considered, with recorded air temperatures respectively of 35 °C at 3 pm and 28 °C at 10 pm, at a reference weather station. The results of the simulation show temperature differences up to almost 10 °C in the daytime (3 pm) between urban open spaces with impervious cover (squares, streets) and green areas, especially related to the shading effect of the tree canopy. At night (10 pm), the air temperature differences are more contained. In particular, impervious open spaces maintain air temperatures 4 °C higher than those recorded at the weather station, while in areas with tree cover temperatures are about 2 °C lower.