Benefits of Green Walls: Assessment of Energy Cost Saving

Abstract

With the rapid urbanisation, most parts of the world have become a concrete jungle and yet the concrete structures are rising over the green footprint. This has an adverse effect on the natural environment as well as to habitat. Nowadays, increasing global warming, air temperature and air pollution have become critical issues in urban areas. Spreading greenery is the way to mitigate the effects of urbanisation. Since Sri Lanka is also rapidly moving towards the urbanisation, application of green features on buildings is the best option to spread green within the country. Though the whole world adopted the green wall concept, its application in the Sri Lankan context is still at a lower stage. Thus, this study aims to explore the most substantial benefit of green walls: energy cost saving to promote the green wall application in the Sri Lankan context. The comprehensive literature review identified the benefits of green walls mainly; energy-saving, mitigating the urban heat island effect, act as an insulation layer, increase building durability, enhancing aesthetic appearance, provide habitats, act as a sound barrier, and provide health benefits. Further, thermal performance and energy cost-saving which is a significant benefit of green walls were assessed through the case study. Two comparative buildings; 1. With green wall and 2. Without green wall were adopted to this study. Required data were extracted by obtaining the onsite temperature measurements. The case study findings revealed that the green façade contributes to the significant surface temperature difference reduction compared to the conventional wall which results in a saving of .7 kWh per m² (73%) energy requirement for ventilation per month and as a result, 74% energy cost saving per month. On a positive note, this study concludes that the use of green walls is a suitable alternative to the Sri Lankan context in improving greenery with substantial potential for reducing energy costs for ventilation requirements.

Keywords: Benefits, Conventional Wall, Direct Green Facade, Energy Saving, Green Walls