Numerical modelling evaluation for the microclimate of an outdoor urban form in Cairo, Egypt

Abstract

In order to achieve outdoor thermal comfort it is necessary to understand the interactions between the prevailing climate, the urban form and roughness. The near surface boundary layer is directly influenced by local irradiative and convective exchange processes due to the presence of a variety of different surfaces, sheltering elements and obstacles to air flow leading to distinctive micro-scale climates. The paper presents a micro-scale numerical model for an outdoor urban form for a hot summer’s day in Al-Muizz street located at the Islamic quarter of Cairo, where a few studies have attempted to study these conditions in vernacular settings in hot arid areas where the continuously evolving urban patterns and shaded environments were perceived to produce more pedestrian friendly outdoor environments. In situ measurements are used to validate the ENVI-met results which showed an overall agreement with the observed ones, representing adequate mean radiant temperature (Tmrt) which is one of the most important meteorological parameters governing human energy balance and has therefore a strong influence on thermal sensation of the pedestrians using the open public spaces and generating a micro-climatic map as an initial step in addressing the urgent need for a modelling platform accessible to urban designers, architects, and decision makers towards sustainable urban forms.

Keywords

• Thermal comfort
• Urban microclimate
• ENVI-met
• Mean radiant temperature