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Urban geometry and environmental performance in real urban forms

Chatzipoulka, Christodouli (2017) Urban geometry and environmental performance in real urban forms. Doctor of Philosophy (PhD) thesis, University of Kent,. (KAR id:64332)

Language: English
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Solar radiation is energy, a natural and inexhaustible source of heat and light, and as such a major factor to be considered for enhancing urban environmental sustainability. Solar availability on buildings determines to a large degree their active and passive solar potential; whereas, the insolation of open spaces affects their microclimate and in turn, their use and liveability. Solar objectives are thus multiple and may also be conflicting in time and space, especially in temperate climates, where thermal comfort needs vary in seasons.

The subject of the thesis is the relationship between urban geometry and environmental performance of urban forms, explored at the neighbourhood scale and in real urban areas. Specifically, the research investigates statistically casual relationships of urban geometry with environmental phenomena related, directly or indirectly, to the availability of solar radiation. Full consideration is given to the varying solar geometry as a major parameter affecting the interaction between urban geometry and solar radiation, lending it a temporal and geographical -related to latitude- character. The research subject is explored through three distinct studies, which share the same methodology investigating particular topics under the same thematic umbrella. The first and the third study, in the order of these being presented, investigate phenomena occurring in open spaces, namely insolation and thermal diversity; whereas, the second study examines solar availability in open spaces and on building façades.

In the methodology, urban geometry is distinguished into built density, which is associated negatively with solar availability but positively with sustainability at the city-scale, and urban layout. The former expresses total built volume in a site, and the latter is represented by a set of quantified geometric parameters which characterise the way in which the built volume is allocated and distributed within the site. This distinction aims to provide evidence for the significance of urban layout in modifying the solar urban environment as well as addressing conflicting solar design objectives. The performance of the urban forms is examined through a series of performance indicators, namely sky view factor, insolation, solar irradiance and thermal diversity values. Both urban geometry variables and performance indicators are calculated on average in each urban form. The great size of the sample analysed allows their relationships to be investigated in statistical means.

The research belongs to the new era of urban environmental studies which make use of digital 3D models of cities to study spatially expressed phenomena in the built environment. It is based entirely on the analysis of existing urban forms, of 500x500m area, found in two European cities, London and Paris. London constitutes the main case study city, whereas Paris is examined for comparison purposes. The two cities are located at similar geographical latitudes and within the same climatic context, but their urban fabrics exemplify very different geometries. The geometric and environmental analysis of the urban forms as well as the elaboration and processing of the output data are performed using computer-based tools and methods, such as MATLAB software and image processing techniques applied in urban digital elevation models (DEMs) and, SOLWEIG and the RADIANCE-based software, PPF, for SVF and solar simulations.

The research findings contribute to the field of urban environmental studies and design at multiple levels, presenting a significant theoretical, practical, and methodological value. First, they produce a critical insight about the factors affecting the relationship of urban geometry and sun-related phenomena occurring in the urban environment and lending it a dynamic character. In addition, they provide solid evidence about the enormous potential of urban geometry for promoting multiple -and sometimes conflicting- solar and urban design objectives, informing the relevant on-going discourse. Third, having as case studies real forms in London and Paris, a part of the findings is interpreted into urban design guidelines for enhancing the environmental performance of new and existing areas in the two cities. Last, as the research employs new methods and techniques to explore diverse topics, some of which are relatively new in the literature, it constitutes an important, methodological precedent for future research works.

Item Type: Thesis (Doctor of Philosophy (PhD))
Thesis advisor: Nikolopoulou, Marialena
Thesis advisor: Watkins, Richard
Uncontrolled keywords: urban geometry; density; urban layout; sky view factor; solar geometry; solar exposure; solar availability; thermal diversity; real urban forms; London; Paris; DEMs
Divisions: Divisions > Division of Arts and Humanities > Kent School of Architecture and Planning
SWORD Depositor: System Moodle
Depositing User: System Moodle
Date Deposited: 09 Nov 2017 10:11 UTC
Last Modified: 18 Dec 2022 23:57 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

Chatzipoulka, Christodouli.

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