Assessing light performance of vertical greenery shading in tropical climate

Natural light is abundant in tropical climates 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 effectively shade 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. An experiment was conducted using the Vernonia elliptica plant, which thrives 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. Two identical box models measuring 1 m × 1 m × 1 m were utilized for the experiment. The two models were oriented towards the west and north, representing intense and longer light exposure. The first, 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 is doubled. It was also found that denser foliage with longer leaf strands produced better results, specifically at low altitudes. These results can be used to implement vertical greenery shading in high-rise office buildings.