Vertical greenery as natural shading of glass facades: Bioshading coefficients for 4 climbing plant species for assessment of shading performance
Maximilian Poiss, Anna Briefer, Bernhard Scharf, Philipp Spörl, Rosemarie Stangl
Abstract
Challenges of climate change like rising temperatures increase heat stress especially in the built environments of temperate continental climates, accelerated by the urban heat island (UHI) effect. Green infrastructures (GI), including vertical greening systems (VGS) offer a multi-beneficial method for thermal regulation of urban environments and thermal comfort. A study was designed to determine shading effects and dynamics of the climbing plant species Vitis coignetiae, Humulus lupulus, Wisteria sinensis and Aristolochia macrophylla in the annual cycle on southeastern façades in Söll, Austria. Each species showed a reduction in solar irradiation (I sol ) input onto the building’s façade of higher than 80 %. H. lupulus was found to have the highest and longest shading capacity. This study further bridges the research gap of climbing plant evaluation by analysing seasonal patterns focusing on Plant Coverage (PC), Wall Leaf Area Index (WLAI), Bioshading Coefficient (BSC), and annual shading dynamics. The findings have practical implications for performance-targeted green shading and VGS design and care and maintenance strategies. Additionally, this work provides novel species specific monthly mean BSC values that reflect seasonal shading dynamic of deciduous plants. The data can be usefully applied in building physical calculations and modelling for comparison of conventional and GI-based alternatives, their function and efficiency.