CBA Evaluation of Green Walls Implementation in Tehran City

Environmental issues and the cities losing their natural context have motivated the urban designers to seek for reclamation of urban critical elements, such as green spaces and natural landscapes, and apply new technologies to achieve this goal. Vertical green surfaces are one of the technologies which have become attractive during the recent years. This technology, like any new system, has some advantages and challenges. One of the important challenges for these surfaces is their financial efficiency. In this study, Cost Benefit Analysis (CBA) is used to evaluate the mentioned challenge. Considering the financial gain of these surfaces along with the cost of their installation and maintenance, a better perception of their financial efficiency would be obtained. The costs of implementation and maintenance were calculated based on the data from relevant companies in Tehran and the financial gain was estimated by reduction of energy consumption in a simulated building with green wall. Findings of this study show that costs of implementing and maintaining green surfaces is much more than what is gained due to reduction of  cooling/heating loads in a building. Due to high costs of green walls installation and maintenance, they do not seem to be affordable by considering the reduction of energy consumption costs. Besides, other mentioned issues including oxygen production, carbon tax reduction, increase of building real estate value, energy reduction in the power plants, and reduction of costs of air pollution which can reduce the associated costs are related to the application of plants but not solely green walls. Hence, by applying various forms of vegetation in green spaces, the above-mentioned benefits can be achieved at very low costs.