Assessing Light Performance of Vertical Greenery Shading in Tropical Climate

Abstract

In tropical climate, natural light is abundant and advantageous for incorporating daylighting into building designs. However, this daylight intensity often leads to excessive brightness indoors, specifically in high-rise buildings with glass façades. In addressing sustainability concerns, incorporating greenery outside glass façades can serve as effective sun-shading, and alleviate eyestrain for building occupants. Therefore, this study aimed to investigate the effectiveness of plant leaves in reducing the high light intensity on glass facades. To achieve this, an experiment was conducted using the Vernonia elliptica plant, a plant known to thrive in medium to high sunlight in tropical climates. Three different leaf area indexes (LAI) were examined in this study as the independent variables, while light illuminance and luminance served as the dependent variables. To experiment, two identical box models measuring 1m x 1m x 1m were utilized. The two models were orientated towards the West and North, representing intense and longer light exposure. The first, which is the base case, featured a glass façade without any other additional element, whereas the other incorporated greenery on its glass façade. The obtained results indicated that the impact of leaf density on illuminance and luminance is significant, specifically when the LAI was doubled. It was also found that denser foliage with longer strands of leaves produced better results, specifically at low altitudes. These results can be used for the implementation of vertical greenery shading in real high-rise office buildings.