Benefits of implementing vertical greening in tropical climates

Abstract

With the globalization and population growth, urbanization trends have attracted higher number of people to towns and cities causing very high population densities and space scarcity. Because of the current trends more and more buildings are being constructed causing a grave danger for the environment. This directly and indirectly increase the vulnerability of cities special in tropical context to climate change and related thermal issues due to the increasing temperature and urban heat island effect. Urbanisation has led to loss of greenery in urban areas directly causing the loss of biodiversity as well while increasing the building densities. Vertical greening is identified and implemented as an interesting integration in improving urban environmental quality and life standards which has the potential of solving the above issues. A research series was initiated with the aim of implementing a Vertical Greening System (VGS) to achieve the maximum benefit in terms of thermal performance in Tropical Sri Lankan context. The paper presents findings of the field study carried out to identify the thermal performance of existing VGS in Sri Lanka, an experimental field study done to identify the plant type best suited for the proposed VGS to enhance the thermal performance of the VGS and an experimental simulation study conducted to identify the benefits in building scale. Results of the on-site investigation of existing VGS revealed Living Walls to be better in thermal performance with a record of maximum temperature reduction of 10.16 °C,3.31 °C and 2.11 °C in external wall surface, internal wall surface and internal air temperature respectively. From the shortlisted plants the experimental field study signified Axonopus compressus as the best plant species recording a maximum temperature reduction of 10.08 °C and 3.15 °C in external wall surface and internal wall surface temperature respectively while proving to be better in survival and maintenance. Further the simulation studies signified a possible maximum internal temperature reduction of 4.89 °C during a day and a significant reduction of year-round energy consumption of building in building scale by introducing vertical greening to all facades.