Fully enclosed vegetated courtyard in hot humid tropics

Abstract

Vegetation is considered a prominent strategy to improve the overall thermal performance of a courtyard. Most tropical fully-enclosed courtyard buildings are characterised with vegetation, but empirical studies on its effects remain to be limited. This study aims to examine the thermal performance of a fully-enclosed vegetated courtyard in hot, humid tropical weather, in order to develop design strategies for enhancing its performance. Field measurements and computer simulations using Envi-met V4.2 software and Rayman Pro 2 model were carried out to measure parameters such as air temperature, mean radiant temperature, and physiological equivalent temperature. Field measurements were conducted on a fully-enclosed courtyard building in the Raja Zarith Sofiah library, Universiti Teknologi Malaysia, for validation against computer simulations. In addition, five courtyard ratios comprising 1:1:1, 1:2:1, 1:3:2, 1:2:2, and 1:3:3, were selected and simulated with different leaf area density (LAD) values, namely, 0.93 LAD with example of melaleuca leucadendron (ml), 7.9 LAD with example of Mesua ferrea (mf), and 9.7 LAD with example of ficus benjamina (fb), whereby the percentage of the vegetated area was 25%, 50%, and 75% respectively. East-West orientation was used for courtyard ratios of 1:1:1, 1:2:2, 1:3:3, 1:2:1 and 1:3:2. This is because the East-West orientations are the worst scenarios, as they are the most exposed to solar radiation compared to the North-South, Northwest-Southwest and Northeast-Southwest orientations for the courtyard. The results reveal that 9.7 LAD (fb) recorded the highest average temperature reduction of 1.2°C, followed by 7.9 LAD (mf), with an average air temperature reduction of 0.71°C, and 0.93 LAD (ml), with an average air temperature reduction of 0.34°C. Finally, the study identified the quantity and type of LAD for effective shading and evapotranspiration cooling process during the hottest hours. Besides, the cooling effects were more significant with a larger percentage of LAD. The findings from this research serve as design strategies for the effective use of vegetation to enhance courtyard thermal performance.