Title: Urban form, building regulations and outdoor thermal comfort in the tropical city of Chennai

Abstract

Urban population in most of the global cities are constantly increasing. In India, this rapid growth has compelled local governments to revise planning regulations on a regular basis, with the goal of providing urban living more affordable. As a result, the built density was increased without considering the impact of such changes on human thermal comfort. The main aim of this study is to evaluate the impact of the resultant urban form of changing building regulations on the outdoor thermal comfort and intensity of heat island in Chennai. The study has three objectives: first, to determine the variance in urban heat island intensity over time using the traverse approach. Second, examine the performance of an urban neighbourhood’s outdoor thermal comfort by determining the relationship between urban built form and microclimate parameters. Third, to understand the relationship between development regulations and urban morphology, as well as their impact on microclimate parameters and outdoor thermal comfort. The traverse survey conducted in the Chennai Metropolitan Area revealed a heat island intensity of 4.5°C in winter (figure 1) and 2.5°C in summer. The research also investigated the impact of the existing urban form guided by the development control rules of Chennai Metropolitan Development Authority. The study found that the 2019 regulation improved the outdoor thermal comfort when compared to the existing built morphology in the urban neighbourhoods. The thermal performance of the 2019 regulation can further be enhanced through increasing the pervious layer in the setbacks by 50 percent with green cover and canopy trees. This research can aid urban planners and design professionals in the formulation of urban guidelines with appropriate urban form in Chennai city which mitigates urban heat island intensity and improves outdoor thermal comfort.