Economic performance of green walls: A systematic review

Green walls are becoming an interesting solution to address the potential issues due to loss of greenery in the urban built environment. Even though green walls offer numerous benefits, the application pace of this concept seems slow in many parts of the world including Sri Lanka, which could be primarily due to the perception that the construction of green walls may involve additional costs compared to conventional walls and due to lack of awareness of its performance. This has driven the recent researchers to investigate the economic performance of green walls. However, those studies are limited to given local contexts, thus, the knowledge is scattered. Therefore, this paper aims to explore the economic performance of green walls in the global context collectively using a systematic review towards understanding the differences. Filtering the search for the period of 2010 to 2022 offered 15 out of 103 research articles suitable for the analysis. The cost data extracted shows high variability related to different characteristics of green walls, building envelopes, and climatic conditions. According to the review, the maintenance stage accounts for the highest portion of the Life Cycle Cost (LCC) in any type of green wall. The direct green façade is the cheapest option with lowest LCC compared to the indirect and living wall types while the living wall is the expensive type due to presence of more components. The review further confirms that in most instances, the economic benefits of green walls; increase property value, façade longevity, tax incentives, and energy-saving tend to offset the cost of green walls. It is expected that this collective review outcome would better guide the decision-making process of green wall implementation in a given context.