Dependence of outdoor thermal comfort on street design in hot and dry climate
type: CreativeWork
description: The present work addresses the contribution of street design toward the development of a comfortable microclimate at street level for pedestrians. The work is design-oriented and seeks to provide a quantitative knowledge readily interpretable from the perspective of urban designers. Street geometries are investigated, including various aspect ratios, i.e. height-to-width ratio H/W, solar orientations and a number of design details. First, symmetrical urban canyons with H/W equal to 0.5, 1, 2 and 4 and for different solar orientations (i.e. E-W, N-S, NE-SW and NW-SE) are studied. Secondly, asymmetrical profiles with different openness to the sky are investigated together with the role of ar-chitectural details such as galleries, horizontal overhangs on façades and rows of trees, considered as possible ways to improve the outdoor thermal comfort further in the summertime. Moreover, the analysis focuses on the local differences in the thermal sen-sation across the street, i.e. street centre vs. street sides, which influence the frequenta-tion of the street. A special emphasis is placed on a human bio-meteorological assess-ment of these microclimates by using the thermal index PET, Physiologically Equiva-lent Temperature. The investigation is carried out by using the three-dimensional numerical model ENVI-met 3.0, which simulates the microclimatic changes within urban environments in a high spatial and temporal resolution. Model calculations are run for typical summer conditions in Ghardaia, Algeria (32.40° N, 3.80° E), a subtropical region characterized by a hot and dry climate. Additionally, short-term field measurements are carried out in Freiburg, Germany, and in Ghardaia (Beni-Isguen), Algeria, during the summer 2003. In the former site, the microclimate changes due to geometry and the effects of the street irradiation patterns on the heat gained by a human body are dealt with in detail. In the latter site, a quantitative evaluation of the thermal effectiveness of …
abstract: The present work addresses the contribution of street design toward the development of a comfortable microclimate at street level for pedestrians. The work is design-oriented and seeks to provide a quantitative knowledge readily interpretable from the perspective of urban designers. Street geometries are investigated, including various aspect ratios, i.e. height-to-width ratio H/W, solar orientations and a number of design details. First, symmetrical urban canyons with H/W equal to 0.5, 1, 2 and 4 and for different solar orientations (i.e. E-W, N-S, NE-SW and NW-SE) are studied. Secondly, asymmetrical profiles with different openness to the sky are investigated together with the role of ar-chitectural details such as galleries, horizontal overhangs on façades and rows of trees, considered as possible ways to improve the outdoor thermal comfort further in the summertime. Moreover, the analysis focuses on the local differences in the thermal sen-sation across the street, i.e. street centre vs. street sides, which influence the frequenta-tion of the street. A special emphasis is placed on a human bio-meteorological assess-ment of these microclimates by using the thermal index PET, Physiologically Equiva-lent Temperature. The investigation is carried out by using the three-dimensional numerical model ENVI-met 3.0, which simulates the microclimatic changes within urban environments in a high spatial and temporal resolution. Model calculations are run for typical summer conditions in Ghardaia, Algeria (32.40° N, 3.80° E), a subtropical region characterized by a hot and dry climate. Additionally, short-term field measurements are carried out in Freiburg, Germany, and in Ghardaia (Beni-Isguen), Algeria, during the summer 2003. In the former site, the microclimate changes due to geometry and the effects of the street irradiation patterns on the heat gained by a human body are dealt with in detail. In the latter site, a quantitative evaluation of the thermal effectiveness of …
author: Ali-Toudert, Fazia
keywords: Straßenschlucht, human-biometeorologie, PET, Himmelrichtung, Freiräume, urban canyon, aspect ratio, street orientation, ENVI-met, gallery, overhangs, urban vegetation
date modified: 2026-07-24T02:22:33Z
provider: University of Freiburg
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Freiburg