Controlling solar radiation through urban form manipulation to improve thermal performance of outdoor spaces in Upper Egypt

Although the geometry of urban settlements can significantly affect local microclimates, planning of new urban communities in Upper Egypt does not amply account for the requirements of the arid climate that they are situated in. The thermally stressful conditions resulting from this can have negative implications on sustainable lifestyles and energy consumption. Nonetheless, expansions are currently being planned following the same trends for these deserted ghost towns. On the other hand, in the Greater Cairo Region (GCR), older urban communities were originally planned with similar characteristics to these deserted towns. However, they have experienced an unplanned evolutionary process over the last decades. These settlements became denser as residents built additions vertically or replaced existing structures with higher ones. Consequently, the geometric parameters of outdoor spaces have become more complex, with significant impacts on the local micro climate. The research at hand is triggered by the following inquiries: To what extent can urban form manipulation affect outdoor thermal comfort? How does the thermal behavior vary with variation of spatial scales (quarters, blocks and streets)? Which urban form variables are most associated with change in thermal comfort at each spatial scale? And how can these insights be translated into simple and easy to apply guidelines for planning and transforming new urban communities in Upper Egypt? Using New Aswan as a case study (representative of new urban communities in Upper Egypt) and drawing from the richness of the older planned communities in GCR, this research attempts to explore the answers of the aforementioned questions. After explorations in literature of urban morphology and its relation to energy efficient mobility, a qualitative criterion was formulated by which four quarters from GCR were chosen as samples. Additionally, a quarter was chosen from New Aswan as a morphological representative for the status quo in Upper Egypt. Using ENVI-met version 4.4.3 simulation model that is calibrated according to measurements taken at Aswan University campus, two groups of simulations were conducted under Aswan’s extreme hot climatic conditions in summer. The first group simulates the impact of the urban form of two quarters (with identical layout but are different in their building heights) on Physiological Equivalent Temperature (PET) at pedestrian level. This aims to assess possible densification scenarios for the existing part of New Aswan. The results show that the densification has lowered average PET values by 1 °C throughout the entire quarter and up to 5.5 °C in some of the evolved areas during the daytime hours. However, at other locations within East-West oriented streets the increased heights had a negative effect and was insignificant at the wider spaces. The second group simulates all the quarters from GCR and the quarter from New Aswan with the aim of exploring how key urban form variables can affect outdoor thermal comfort (PET). Urban geometry variations affected average PET by up to 9 o◦C at the scale of individual streets, with prevalence of shade being the most important parameter. Multiple regression analysis showed that urban form variables explain more than half of the variation in PET. Extent of enclosure and Floor Area Ratio were most important at the block scale, while aspect ratio and orientation were the most impactful at the street scale. Based on these results, recommendations for changes in buildings regulations and planning guidelines were suggested. The results of this study are intended to contribute to two fields: the scientific field of research, showing how and in what extent urban form and outdoor thermal comfort are interrelated and the applied field of urban planning, to guide planners of new urban communities in arid climates.

Author dc:creator

• Galal Mohamed Sayed Ahmed, Omar Mohamed

Advisors dc:contributor.advisor

• Pahl-Weber, Elke
• Schäfer, Rudolf
• Mahmoud, Hatem

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Identifier URI

http://dx.doi.org/10.14279/depositonce-12358

OAI identifier oai:identifier

oai:depositonce.tu-berlin.de:11303/13571