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LAI based trees selection for mid latitude urban developments: A microclimatic study in Cairo, Egypt

Fahmy, M., Sharples, S. and Yahiya, M. (2010) LAI based trees selection for mid latitude urban developments: A microclimatic study in Cairo, Egypt. Building and Environment , 45 (2). pp. 345-357. ISSN 0360-1323

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Abstract

To study the leaf area index, LAI, based thermal performance in distinguishing trees for Cairo's urban developments, ENVI-met plants database was used as platform for a foliage modeling parameter, the leaf area density, LAD. Two Egyptian trees: Ficus elastica. and Peltophorum pterocarpum were simulated in 2 urban sites with one having no trees, whilst the second is having Ficus nitida trees. Trees LAD values were calculated using flat leaves' trees LAI definition to produce maximum ground solid shadow at peak time. An empirical value of 1 for LAI is applied to numerically introduce LAD values for ENVI-met.

Basically, different meteorological records showed improvements for pedestrian comfort and ambient microclimate of the building using E elastica. About 40-50% interception of direct radiation, reductions in surfaces' fluxes around trees and in radiant temperature T-mrt in comparison to base cases gave preferability to E elastica. The lack of soil water prevented evapotranspiration to take place effectively and the reduced wind speeds concluded negligible air temperature differences from both base cases except slightly appeared with the F elastica. Results show that a flat leaves tree if does not validate LAI of 1, the ground shading would not fulfill about 50% direct radiation interception and this value can be used as a reference for urban trees selection.

Further simulations were held to investigate LAI value of maximum direct radiation interception.

Performing additional simulations, F elastica of LAI of 3 intercepted almost 84% of direct radiation and revealed implications about urban trees in practice and its actual LAI. (C) 2009 Elsevier Ltd. All rights reserved.

Item Type: Article
Copyright, Publisher and Additional Information: © 2009 Elsevier. This is an author produced version of a paper subsequently published in Building and Environment. Uploaded in accordance with the publisher's self-archiving policy.
Keywords: LAI; LAD; Peak time; ENVI-met
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Mechanical Engineering (Sheffield)
The University of Sheffield > Faculty of Social Sciences (Sheffield) > School of Architecture (Sheffield)
Depositing User: Miss Anthea Tucker
Date Deposited: 16 Dec 2009 10:07
Last Modified: 08 Feb 2013 16:59
Published Version: http://dx.doi.org/10.1016/j.buildenv.2009.06.014
Status: Published
Publisher: Elsevier
Refereed: Yes
Identification Number: 10.1016/j.buildenv.2009.06.014
URI: http://eprints.whiterose.ac.uk/id/eprint/10253

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