Mitigation Strategies of the Urban Heat Island Over Greater Cairo Metropolitan Area, Egypt Utilizing ENVI-Met Model

Abstract

The formation of urban heat islands (UHI) over cities is the main challenge to the urban environmental sustainability worldwide. To mitigate UHI effects, passive cooling using cool materials and/or greening is thought to be the most effective strategy. As urban greening is relatively nascent in the urban literature, a multitude of research gaps are still to be filled, especially for the cities belonging to the hot arid belt. The present study aims to explore to what extent are three greening strategies (façade greening, roofs greening and urban parks) feasible in UHI mitigation using case study in Greater Cairo Metropolitan Area (GCMA). This task is best achieved through modeling, using the micro-scale numerical model ENVI-met, to simulate the probable outdoor cooling effects of greening for a hot summer day. The results, for this specific case, show that both façade and roof greening would yield up to 0.5°C average reduction of air temperature compared with the actual case, while the cooling effects of the hypothetical pocket parks may be as high as 7 °C during day time till 15.00 PM, and after that parks would exhibit heat island properties. The study findings may assist in better planning of urban green spaces to increase their cooling potentialities. Keywords: ENVI-met; Modeling; Passive cooling; Urban greening; Urban heat island.