Thermal comfort provided by street trees in cities

ABSTRACT The lack of a correct urban planning system associated with the increasing growth of population has led to several problems in the social-environmental context; amongst these are the weather changes that impair people’s quality of life. The aim of this study is to compare the Universal Thermal Climate Index (UTCI) on streets with and without trees in the city of Curitiba, Brazil. We selected three sample areas, each consisting of a stretch of street with and without trees planted. The meteorological variables were monitored with a Kestrel® pocket weather tracker and thermal stress measurer. The data were gathered between 9 am and 3 pm, with a one-minute break, repeated in the seasons of the year, starting in winter 2011. The UTCI was tested by interviews with pedestrians on the street. The results show that the indices on streets with trees were better than on those without trees. The average values of the UTCI for streets with trees are “comfortable” (22.4°C), while those on streets without trees were classified as “stress due to moderate heat” (26.0°C). The percentage of hits of the UTCI was 58.9%. These results show the importance of trees in the city of Curitiba, as they create a more thermally comfortable microclimate.