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The impact of urban geometry on the radiant environment in outdoor spaces

Chatzipoulka, Christina, Nikolopoulou, Marialena, Watkins, Richard (2015) The impact of urban geometry on the radiant environment in outdoor spaces. In: 9th International Conference on Urban Climate. ICUC9 9th International Conference on Urban Climate jointly with 12th Symposium on the Urban Environment. .

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Abstract

Urban geometry, namely the quantitative relationship of building volumes and open spaces (i.e. built density) and their spatial configuration (i.e. urban layout), is a major modifier of urban microclimate. This paper presents the results of an ongoing research which explores the impact of urban geometry on the radiant environment in outdoor spaces, with direct implications for urban microclimate and outdoor thermal comfort. In particular, the research investigates the relationship between a set of urban geometric indicators (such as Built Density, Site Coverage, Mean building Height and Frontal Area Density) and Mean Radiant Temperature (Tmrt) at the pedestrian level, in different areas of London.

The simulation results show that at night-time and in fully overcast conditions, the outdoor spaces of central London’s urban squares are warmer than those of west and north London, due to greater longwave radiation emitted and reflected by building volumes. In contrast, on sunny days, average daytime Tmrt values have been found to be higher in North London’s urban squares due to the larger insolation of their outdoor spaces. Additionally, the statistical analysis has shown that in the absence of direct solar radiation, the correlation between the geometrical variables and average values of Tmrt is very high with an almost perfect linear relationship between the geometrical variables and average SVF values (r2= 0.980). In the presence of direct solar radiation, the strength of the correlation varies with the sun altitude angle; the higher the sun altitude angle, the higher the correlation. In particular, a threshold altitude angle of 20 degrees has been identified, above which the correlation of average Tmrt values with urban geometry approximates that of night-time / cloudy hours. Finally, further statistical tests showed that site coverage (built area over site area) and frontal area density (façades’ total area over site area) are the strongest indicators among those considered in the analysis.

Item Type: Conference or workshop item (Paper)
Subjects: Q Science
Divisions: Faculties > Humanities > Architecture
Depositing User: Richard Watkins
Date Deposited: 04 Dec 2015 16:48 UTC
Last Modified: 23 Jan 2020 04:11 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/52695 (The current URI for this page, for reference purposes)
Nikolopoulou, Marialena: https://orcid.org/0000-0002-0528-2145
Watkins, Richard: https://orcid.org/0000-0003-3071-9510
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