Green Walls, a Critical Review: Knowledge Gaps, Design Parameters, Thermal Performances and Multi-Criteria Design Approaches

Abstract

The green wall is an engineered technology for stormwater management and climate change mitigation at the urban level. At the building scale, these energy efficiency measures are suitable for improving indoor comfort conditions and for reducing energy needs. Several guidelines are available about vertical greening systems, but these propose design parameters and performance evaluation criteria, often incomparable. In order to facilitate the implementation of proper technical standards, this paper proposes a critical review of more recent scientific investigations. All parameters for the design optimization are discussed as well as the achievable social and private benefits by taking into consideration the type of study (numerical or experimental), the climate conditions, the analysis period, all technical requirements of the green layer as well as of the back wall. The review underlines that a multi-criteria design approach is needed for green vertical systems. Thus, the paper is concluded with a SWOT analysis, evidencing “strengths”, “weaknesses”, “opportunities” and “threats”. The analysis shows that the highlighted benefits will acquire greater relevance considering the increase in global temperatures and the growing need to redevelop densely built urban centers, while some negative aspects may be filled in the future with a deeper preparation of designers and careful choice of materials. The review paper shows, therefore, drivers and barriers occurring designing and implementing green walls.

Closing Water Cycles in the Built Environment through Nature-Based Solutions: The Contribution of Vertical Greening Systems and Green Roofs

“…Compared to the provision of ecosystem services, research on ecosystem disservices (ecosystem outputs that diminish human well-being, caused by NBS_u) is relatively scarce [145][146][147]. Open questions include fire-resistance in VGS [148], the quality of runoff water from GR [149][150][151], and air quality effects [152][153][154].…”

Are green wall technologies suitable for major transport infrastructure construction projects?

“…Green wall technologies are relatively new to the transport and infrastructure industry, however green walls in architecture and buildings have a large history dating back to the Babylonians, with the famous Hanging Gardens of Babylon as an ancient wonder of the world (Collins et al, 2017). For this reason, green facades are currently more widely implemented across buildings due to the ease of constructability, low cost and aesthetic in comparison to living walls (Ascione et al, 2020). Living wall systems require more research, design, construction and maintenance than a green façade and is still a relatively new concept that is undergoing extensive research into its optimisation (Sendra-Arranz et al, 2020)…”

Leaf Coverage Quantification for the Design of Vegetated Shading Geometries Using Algorithmic Modeling, Coupled with Imaging Software

“…In the last twenty years, green façades have been much investigated and explored through different methodologies. However, although previous studies (SCHERER ;FEDRIZZI, 2015;DAVIS et al, 2017;RILEY, 2017) attest these systems have several benefits for the building and the urban area (ASCIONE et al, al., 2020), there are still some gaps and limitations related to computational simulation methods to explore the behavior of this system.…”