A Parametric-Simulation Method to Study the Interconnections between Urban-Street-Morphology Indicators and Their Effects on Pedestrian Thermal Comfort in Tropical Summer

Abstract

Numerous studies have explored the impact of urban morphology and geometry on outdoor thermal comfort, intending to provide practical guidelines for urban designers. However, research findings have been inconsistent, in part due to differences in the climatic settings and the investigated heat-stress indicators. This study proposes a parametric-simulation framework to observe the behavior of thermal comfort according to the possible combinations of building density (BD), street aspect ratio (AR), and orientation. Conducted specifically under a hot-and-humid tropical-savanna summer condition, the study found that building density and aspect ratio were negatively correlated to the Universal Thermal Climate Index (UTCI), with R2 coefficients of 0.99 and 0.91, respectively. The UTCI was improved by a 1.0 °C per 10% increase in BD and by a 1.02 °C per unit of AR increase. The performance of street orientation was significantly influenced by wind direction, and strong inter-influences were found between the three morphology factors. These findings are useful guidelines not only for designing urban morphology but also for intuitively identifying the need for complementary vegetation and cooling materials when morphology indicators cannot reach their efficiency targets (e.g., when AR < 3.0 or building density is limited by local regulations and project specifications).

A Computational Fluid Dynamics Modelling Approach for the Numerical Verification of the Bioclimatic Design of a Public Urban Area in Greece

“…[16]. Based on its advantage of containing special urban physical models (e.g., evaporation from water surfaces, evapotranspiration from vegetation, basic turbulence modelling and thermal comfort indices) relieving the user of own-defined functions and codes, the ENVI-met software has been extensively used in urban planning studies, mainly for exploring the impacts of alternative design scenarios [18][19][20][21][22], urban configurations and morphologies [23,24] and novel artificial materials such as supercool materials [25] or nature-based solutions [19,26,27]. On the other hand, taking into account its flexibility in coupling with zonal models for assessing urban microclimate effects on building energy performance [16,28], but especially due to its numerous alternatives regarding grid meshing in complex geometries and turbulence modelling [16], the Ansys FLUENT software has gained popularity in advanced urban planning studies.…”