A Statistically Rigorous Approach to Experimental Design of Vertical Living Walls for Green Buildings

Abstract

Living walls (LW) have been widely proposed as a form of green infrastructure to improve aesthetics, energy consumption, and microclimate in urban environments by adding densely-planted vegetation to the outside walls of buildings. Scientific studies using multiple treatments in a single LW face challenges due to the close physical proximity of different treatments, particularly the potential for plants above to influence those below. A study on a west-facing LW was undertaken to investigate 36 unique treatments in Adelaide, South Australia, for nine months. The LW comprised combinations of six native plant species, three soil substrates and two irrigation volumes. The LW consisted of 144 modular trays mounted on a wall in a 12 × 12 grid with four replicates of each treatment. The location of each treatment was designed to account for a cascading carry-over effect that may be present when one plant is placed above another. Carry-over effect of the model designed showed mixed results among the plant groups identified. It was also found that long-form plants can significantly shade smaller plants below them. Experimental research into the performance of plants in mixed species LW should consider the carry-over effect to account for this.

The Influence of Plant Type, Substrate and Irrigation Regime on Living Wall Performance in a Semi-Arid Climate

“…The design and location of a LW from [27] was replicated and adapted in this study. The LW comprised 144 Elmich Versiwall modular LW pots.…”

“…Plant selection may involve consideration of foliage, colour, texture, leaf shape, plant size, vigour and growth habit [20,21]. Previous research on LWs have utilised perennial [22][23][24], drought-tolerant succulent [25], salttolerant [26] and native plants [8,27]. One previous study recommended evergreen shrubs to be planted on living walls, while evergreen climbing species were preferred for green façades [28].…”

Evaporative Cooling Effect of Water-Sensitive Urban Design: Comparing a Living Wall with a Porous Concrete Pavement System

“…The individual pots were 195 mm wide, 207 mm high and 192 mm deep, yielding a total volume of 1.8 L that contained 1.5 L of soil substrate. The living wall was fitted with a drip irrigation system comprising pressure-compensating drippers [20].…”

“…Six plant species were selected, namely, Goodenia varia (GV), Einadia nutans (EN), Dichondra repens (TT) Dianella revoluta (DR), Myoporum parvifolium (MP) and Westringia fruticosa (WF). There were 36 unique combinations of irrigation-substrate-plant, and each was replicated four times in the LW following a statistical design that included carry-over effects [20]. The full experimental design of the LW's plant-substrate-irrigation system is shown in Table 1.…”

Biochar for Vertical Greenery Systems

“…Many studies [21,[29][30][31] have shown that VGS protect against direct, diffuse, and reflective solar radiation. The ability of VGS to absorb noise and increase the acoustic insulation of buildings is well-documented [32].…”