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Analysis of urban thermal environments based on the perception and simulation of the microclimate in the historic city of Tlemcen

Wafa Ghaffour (Department of Architecture, University of Tlemcen, Algeria)
Mohammed Nabil Ouissi (Department of Architecture, University of Tlemcen, Algeria)
Marc André Velay Dabat (Project[s] laboratory - National School of Architecture, Marseille, France)

Smart and Sustainable Built Environment

ISSN: 2046-6099

Article publication date: 5 May 2020

Issue publication date: 17 June 2021

157

Abstract

Purpose

The preservation of historic urban centres prevents anarchic development of the city and ensures a harmonious evolution of the urban form. It also improves the quality of life in the context of climate and environmental change. Morphological and geometric indicators of the urban fabric are key parameters in the formation of external microclimates. They provide a positive effect on the thermal comfort of pedestrians. The objective of this work is to study the impact of the site morphology on the external microclimate and to understand the relationship between the subjective perception and the objective quantification of the thermal environment. The result of this study has allowed us to propose solutions for the creation of a microclimate favourable to the appropriation of outdoor spaces. The authors finally propose guidelines for the design and rehabilitation of the historic site based on the establishment of links between the site's configuration, microclimatic conditions and users' perceptions.

Design/methodology/approach

Part of this study included the analysis of the microclimate of the historic “Bab El Hadid” district of the City of Tlemcen, by developing a questionnaire survey and a numerical simulation validated by measurements of the microclimate the authors made on site. To complete this task, the authors applied the Envi-met 4.1 model during the coldest month of the winter and the hottest month of the summer. Urban parameters are represented at different measurement points characterised by a variability of the sky view factor (SVF).

Findings

The results presented in terms of average expected the predicted mean vote (PMV) voting, solar access and air temperature. They show that thermal conditions are directly related to the SVF, the height/width ratio (H/L) of streets as well as the orientation of urban canyons. The points located in the streets facing North–South, present an acceptable performance. Streets shaded by trees with a canyon aspect ratio of between 1.18 and 1.70 reduce heat stress in outdoor spaces. The PMV models discussed provide information on the most appropriate locations for pedestrians. The authors have proposed urban orientations that could limit unfavourable conditions in outdoor spaces. They are useful for architects and urban planners in the design and rehabilitation of historic centres.

Originality/value

In Tlemcen, the microclimate is not taken into account in the design and rehabilitation of urban fabrics. For this specific purpose, the authors want to stress in the research the importance of safeguarding urban heritage through the renewal of the old city and the bioclimatic rehabilitation of its urban spaces.

Keywords

Citation

Ghaffour, W., Ouissi, M.N. and Velay Dabat, M.A. (2021), "Analysis of urban thermal environments based on the perception and simulation of the microclimate in the historic city of Tlemcen", Smart and Sustainable Built Environment, Vol. 10 No. 2, pp. 141-168. https://doi.org/10.1108/SASBE-12-2019-0166

Publisher

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Emerald Publishing Limited

Copyright © 2020, Emerald Publishing Limited

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