Análise do microclima urbano através de modelagem computacional: estudo de caso em Balneário Camboriú-SC

The urban heat islands are an urban climate phenomenon defined by the positive difference between the air temperature of an urban area to a non-urban one. Factors such as geometry, materiality, pollution, and vegetation influence the intensity of urban climatic phenomena. This study aims to evaluate the effect of geometry and solar reflectance of urban surfaces on the microclimate of a Brazilian coastal city. The methodology is a case study of two areas with different geometries, representing the central region of Balneário Camboriú, Santa Catarina. The measurement of urban heat islands' intensity occurs in two seasons of the year (winter and spring). The average of the heat islands' intensity was up to 1.0 °C at night and 2.5 °C during the day. The area with the highest horizontal and vertical density had less intense heat islands during the day due to the shading caused by the buildings. At night, this area's lower sky view factor reduces long-wave radiation heat exchange with the sky, resulting in higher air temperatures. The influence of solar reflectance was evaluated through computer simulations of scenarios with different combinations of solar reflectance on the roofs, facades, and pavements. The ENVI-met version 4.4.6 model was used and validated according to field measurements. The simulations show that, in general, surfaces of high solar reflectance contribute to the reduction of air temperature. The geometry of urban space also defines the type of surface that influence the most air temperatures. In denser areas, the solar reflectance of the facades exerts more significant temperature variation. At the same time, in open urban spaces, with a higher sky view factor, the roofing and paving surfaces are more important. Although dependent, the effect of the solar reflectance of the surfaces is secondary concerning the effects of the geometry, considering the air temperature variation that their modifications cause. Impacts on urban microclimate extend beyond air temperatures. The solar radiation incident on the paving of an urban canyon with surfaces of high solar reflectance can be up to three times greater than one with low reflectance. The low sky view factor area shows reduced long-wave radiation heat loss from urban elements regarding net thermal radiation. Furthermore, the deep urban canyon (H/W > 2) showed more sensitivity to the surface's solar reflectance changes than a less dense area.