A state of the art review of the impact of Vertical Greenery Systems (VGS) on the energy performance of buildings in temperate climates

Rapid urbanization and climate change concerns have led to a growing drive to integrate nature into the built environment. It is expected that London will face increasing risks of flooding, overheating and drought, through hotter drier summers and warmer wetter winters. In response, the Mayor of London adopted new policies for encouraging the use of living roofs and green walls. Greenery systems are considered as promising solutions for improving energy and thermal efficiency of buildings as well as reducing pollution, encouraging biodiversity and water runoff, reducing Urban Heat Island (UHI) effects and improving the microclimate overall. The research aims to review the current state-of-the-art literature concerning the potentials and limitations of vertical greenery systems on energy and thermal performance of buildings in temperate climates. This review paper synthesises and summarizes the literature with regards to vertical green systems (VGS) when used as a passive design strategy to enhance energy savings in buildings. From the review of the literature, some key aspects to consider when designing VGS are outlined, such as climate influence, the plant species grown and the different operating mechanisms as associated such as shade, evapotranspiration, insulation and wind barrier. The results achieved from the literature review clearly indicate that green walls may be considered as key solutions to mitigate operational energy consumption of buildings as well as provide thermally comfortable indoor and outdoor environments. The results of this research will prove useful to builders, architects, engineers and policy makers as it will provide an in-depth understanding of the potential of VGS to mitigate building related energy consumption in a renewable, sustainable, energy-efficient and cost-effective way.