Effects of Roadside Trees and Road Orientation on Thermal Environment in a Tropical City

Sheikh Ahmad Zaki, Hai Jian Toh, Fitri Yakub, Ahmad Shakir Mohd Saudi, Jorge Alfredo Ardila-Rey and Firdaus Muhammad-Sukki
Additional contact information
Sheikh Ahmad Zaki: Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, Kuala Lumpur 54100, Malaysia
Hai Jian Toh: Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, Kuala Lumpur 54100, Malaysia
Fitri Yakub: Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, Kuala Lumpur 54100, Malaysia
Ahmad Shakir Mohd Saudi: Environmental Health Research Cluster, Environmental Healthcare Section, Institute of Medical Science Technology, Universiti Kuala Lumpur, Kajang 43000, Malaysia
Jorge Alfredo Ardila-Rey: Department of Electrical Engineering, Universidad Técnica Federico Santa María, Santiago de Chile 8940000, Chile
Firdaus Muhammad-Sukki: School of Engineering, Robert Gordon University, Garthdee Road, Aberdeen, Scotland AB10 7GJ, UK

Sustainability, 2020, vol. 12, issue 3, 1-23

Abstract: Emerging tropical cities are experiencing rapid population growth and development, which can greatly affect the thermal environments. The effects of roadside trees and road orientation on the outdoor thermal environment were investigated on four different roads in Kuala Lumpur, Malaysia. Field measurements were conducted to assess outdoor thermal environments, where the selection of sites was based on different roadside tree morphological features and road orientations. Outdoor air temperature ( T a ), relative humidity ( RH ), globe temperature ( T g ), wind speed ( WS ), and wind direction ( WD ) were measured. Absolute humidity ( AH ) was estimated based on relative humidity and air temperature. Planting dense canopy trees with an average sky view factor (SVF) of 0.07 reduced the mean radiant temperature ( T mrt ) by 35% and the physiological equivalent temperature (PET) by 25%. East–West (E–W) and Northwest–Southeast (NW–SE) oriented roads had high PET values of 41 °C and 43 °C, respectively. North–South (N–S) and Northeast–Southwest (NE–SW) orientated roads had lower PET values (37 °C), providing improved outdoor microclimate. Roadside trees provided greater cooling potential in E–W and NW–SE oriented roads. The findings are useful for urban road design in tropical cities in order to improve the outdoor thermal environment and pedestrian comfort.

Keywords: Field measurements; Roadside trees; Road orientation; Thermal environment; Thermal comfort; Physiological equivalent temperature (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (8)

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