Impacts of changes in surface albedo on microclimate and pedestrian thermal comfort levels in urban canyons

Abstract

Urban surface albedo is directly related to their ability to absorb energy or reflecting it to the adjacent surfaces, affecting the microclimatic conditions and thermal comfort in the pedestrian level in open space. The aim of this paper is to analyse the influence of changes in albedo of urban surfaces on canyon air temperature and on pedestrian thermal comfort, for mid-sized cities located in the eight Brazilian bioclimatic zones. For this purpose the predictive model canyon air temperature (CAT) and the comfort index ITS have been used. Results showed that impact of changing from low to high surface albedo is negligible for air temperatures whereas an increase of surface albedo tends to worsen thermal comfort conditions at the pedestrian level. Therefore, the use of high albedo should not be prescribed to canyon surfaces indiscriminately, as it requires an assessment of local conditions in order to identify which surfaces have enough solar exposure for an effective use of higher albedo, without negatively affecting pedestrian thermal comfort.

Keywords:
Albedo; Urban canyon; Thermal comfort; Microclimate