A comparative assessment of indirect green façade and conventional walls: perspective of life cycle cost

Purpose Green walls are vertical structures with various plant species that contribute to achieving sustainability in terms of environmental, economic and social aspects. A comparison of green wall performance with a similar type of conventional wall would be the most convincing way of promoting green wall applications than comparing the performance within types of green walls. Hence, this study evaluated the life cycle cost (LCC) of an indirect green facade with a conventional wall in the Sri Lankan tropical climate towards enhancing the adaptation of the green wall concept as an energy-saving solution. Design/methodology/approach The study involved two stages: (1) assessing the thermal performance and (2) calculating the LCC of the indirect green facade and the conventional wall. On-site temperature measurements were taken from various spots on the exterior and interior wall surfaces of each building in different time intervals per day for 21 days from the end of May to the beginning of July. The LCC analysis was performed using the cost data collected through the market survey and document review. Findings The temperature difference between the external and internal wall surfaces of the conventional wall (1.06 0 C) is higher than the green wall (0.32 0 C). This implies that green walls help retain 2/3 of the temperature transferred through a conventional wall, thereby reducing the energy requirement for cooling purposes by 70%. Though the initial cost of a green wall is 19% higher than a conventional wall, maintenance costs of green walls result in 29% savings. This results in a 55% overall annual LCC savings compared to conventional walls. Originality/value There is a dearth of studies to evidence that the cost performance of green walls is more effective than conventional walls in tropical climates, and this study fulfils this research gap. Thus, the findings would be more convincing to clients towards enhancing green wall applications.