Quantifying the thermal performance of green facades: A critical review

Green facades are climbing plants grown either directly against, or on support structures affixed to, external building walls. Like other forms of green infrastructure, they are increasingly being considered as a design feature to cool internal building temperatures, reduce building energy consumption and facilitate urban adaptation to a warming climate. To develop a better predictive framework for green facade thermal performance we reviewed the scientific literature - a literature currently dominated by the disciplines of architecture and engineering, and lacking inter-disciplinary input from plant biology, ecology, horticulture and soil science. We found that many of the studies were prone to research design problems; the small number of experimental studies lacked replication and provided insufficient information about the microclimate parameters measured, while the assumptions of modelling studies were not always delineated or justified. Few studies considered the influence of climbing plant characteristics, and fewer still investigated the impact of green facade design components (support structures, growing media, plant containers and irrigation systems) on green facade thermal performance. As a framework for future green facade research, we propose that standardised methods be adopted, and to this end, set out the minimum microclimatic data required to enable comparative assessment of green fac, ade performance. Furthermore, we stress the need for research on the interaction between climbing plant parameters and building energy balances, as well as on the influence of green fac, ade design elements on thermal performance. Without this shift in approach, unrealistic expectations of green facade performance and their climate change adaptation benefits will persist. (C) 2014 Elsevier B.V. All rights reserved.