INDIRECT GREEN FAÇADE SYSTEMS: A PROPOSAL OF A GLOBAL PERFORMANCE INDICATOR FOR IN/OUT EVALUATION

All the recent studies about green buildings agree upon the importance of their environmental sustainability. This goal finds confirmation also through the recent green building assessment tools, which give higher rating points to environmental aspects of sustainability. Certainly the increase of buildings performances, thanks to an efficient use of energy, water and materials, or waste and CO2 emission reduction, is a tangible way to reduce environmental impact, but it couldn’t be enough in high-density urban areas, where climate change due to global warming intensifies air pollution, surface temperatures and heat island effects (UHI). Therefore, each green building should enhance its environmental contribution, but only if it’s part of a well-balanced urban scale green planning, pointing to urban biodiversity enhancement, ecosystems protection and vegetation improvement as well. It’s not trivial at all to point out that façades are the visual and behavioral joining link between buildings and the environment: from this perspective, façades need to take off their traditional function of partition between indoor and outdoor, to rather become an active and dynamic interface capable to maximize environmental buildings performances. Even if there isn’t an explicit relationship between green building and “vegetal skin”, Vertical Greenery Systems (VGS) represent by now a recognized and strategic way to reduce the overall impact of the built environment, especially in urban areas that have typically limited availability of horizontal spaces at street level for urban greening. This paper highlights the advantages of Indirect Green Façades in both the cases of new and existing buildings, and proposes a global performance indicator for their evaluation. While green roofs are an established technology in construction and assessment of buildings, green façades still find difficult to develop. The introduction of a global performance indicator for Indirect Green Façades could encourage the adoption of this technology in urban regeneration actions, also for low quality building stock typically concentrated in suburban areas, to improve the city image as well. Hopefully, this indicator could be then implemented in several green building assessment tools and will contribute to spread the VGS culture.