The role of building mass configuration and material selection for mitigating the intensity of the urban heat island

Abstract

The knowledge of urban heat island (UHI) mitigation for the materials and geometry of urban areas requires enrichment. This study compares to the thermal conditions on two different building mass configurations (Superblock and horizontal residential areas), that involve geometry aspect (density, orientation) and materials aspect (softscape, pavement, roof, wall). A surface urban heat island (SUHI) survey was conducted using Landsat thermal imagery, followed by ground surveys in selected areas. Data collected in both areas included air temperature, relative humidity, air velocity, and globe temperature area. The results show that the superblock configuration had a low SUHI intensity due to the proportional orientation of East-West-North-South (0.56–0.44) and large shading (average of 0.31 m2). In contrast, in the dense residential areas, the intensity of SUHI was high because the proportion of East-West walls was wider than North-South (0.8–0.2), and the shading was low (average of 0.15–0.16 m2). Façade and ground heating occurred owing to the use of heavy-weight materials, which was indicated in the thermal imagery, with a solar heating index in a vertical cluster mass configuration of 21.7 and a horizontal grid of 55.9. Convective cooling occurred in a vertical geometry because the buildings generated turbulence that removed warm air, whereas it did not occur in a horizontal geometry. The convective cooling index for the vertical cluster mass configuration was 0.62, whereas that for the horizontal grid configuration was 0.09. This indicates that regional planning must incorporate geometric and material considerations to control the urban thermal environments.