Urban morphology parameterization for assessing the effects of housing blocks layouts on air temperature in the Euro-Mediterranean context

Urban environment characteristics directly affect local microclimate and, in turn, changes in local microclimate affect the urban environmental conditions, often resulting in negative consequences on human health and comfort. The study of these interactions is largely supported by scientific literature, but there is a general lack concerning the urban forms influence on outdoor thermal comfort in Euro-Mediterranean cities. In this study, the topic is addressed by investigating performances and characteristics of typical Euro-Mediterranean housing blocks to highlight their effects on local microclimate. Its relevance is related to the need for supporting the assessment of microclimate conditions and outdoor thermal comfort, providing an effective tool that can steer future adaptation policies and design processes. In this perspective, a parametric study is performed by investigating different housing blocks through some morphometric descriptors (density, land-use, canyon geometry descriptors), commonly used in urban and environmental planning. Seven typologies (detached, attached, linear, U-shaped, block with courtyard, block with multiple courtyards, tower) are modelled with the Computational Fluid Dynamic (CFD) ENVI-met v4.4 model, considering three configurations of surface cover and wind direction. For each combination, air temperature at pedestrian level (T-A,T-1.6m) and descriptors are compared to highlight the microclimate performances of urban forms. The results show a close relationship between density, geometry and T-A,T-1.6m distribution, highlighting the perimeter type (which includes three block types: U-shaped, block with courtyard, block with multiple courtyards) as the optimal configuration. Moreover, in some cases, a reduced amount of vegetation can lead to a significant reduction in air temperature, with economic benefits in terms of cost reductions for implementation, management and maintenance. (C) 2020 Elsevier B.V. All rights reserved.