Designing green façades and living wall systems for sustainable constructions

The integration of vegetation, with green roofs and vertical greening systems, is a constantly evolving research field. However green envelopes (especially the most innovative vertical greening systems) are not yet fully accepted as an environmental quality restoration and energy saving method for the built environment, due to the lack of data needed to quantify their effects and to evaluate the real sustainability (environmental and economic) of these. The many systems available on the market allow combining nature and built space to improve the environmental quality in urban areas; green façades, living wall systems offer more surfaces with vegetation and, at the same time, contribute to the improvement of the thermal performance of buildings. From a functional point of view, vertical greening systems compared to green roofs, demand a more complex design, which must consider a major number of variables. In the case of vertical greened surfaces there are numbers of systems to green façades with or without windows, starting from a simple disposition of climbing plants at the base of the façade. Vertical greening systems characteristics and materials involved can either positively or negatively influence theirs performances, with respect to the improvement of the building envelope efficiency and microclimate conditions (cooling potential and the insulation properties), and the environmental burden produced during theirs life span (installation, maintenance, disposal, etc.). This paper analyses characteristics, advantages and critical aspects of four common greening systems, with special attention to micro-scale benefits (the benefits most related to the systems peculiarities) and to environmental sustainability.