One Central Park was designed and built in 2013 to rehabilitate a former brewery site. The building was designed to include a range of green infrastructure initiatives including greenroofs, living facades, and the reuse of recycling demolished materials. The vegetation includes over 250 species of native Australian flowers and plants, with vines and leafy foliage that wrap around the vertical structure.
SESL was brought onto the project to aid in the design, specification and quality control of media for the vertical gardens. This included the topsoil mixes for the plant, tree and flower beds designed with the intent of a 10-15 year lifespan. SESL have continued to conduct work on this project inclusive of quality control and monitoring of plant health.
Design, specification & installation
The initial project was presented with an array of challenges needed to overcome for success. Specific requirements needed to be factored in for heightened wind and exposure to the plants, native plant type, light sensitivities, cost of mineral ingredients and structural integrity.
Wind & Light Exposure
As the plant species would be growing in highly atypical conditions, variant exposure to both light and wind were factored in. SESL calculated the wind velocity profile for the Central Park building, considering variables for:
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wind tunnel effects
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height & wind velocity
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wind acceleration between and at the edges of buildings
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motorway exposure
Turf Design Studios commissioned light and exposure studies for around the buildings. From the 4 light intensity zones that were defined, SESL adapted a plant list to optimise plant suitability to these light intensity zones.
Structural Collapse
Structural collapse was a large concern in the design and specifications for the vertical wall growing mix. Through case study research, it was concluded that the implementation of conventional potting mixes would likely lead to structural collapse.
Additionally, the mix was required to sustain plant life for up to 10-15 years, which is a considerably higher longevity compared to the 1-2 year lifespan of most commercial mixes.
Alternatives such as green walls and recirculating hydroponic systems were discussed on a cost benefit basis with consideration for the high maintenance these solutions would require. It was finalised that to sustain the green walls, it would require a mix with:
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high water holding
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high nutrient holding
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light weight
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high porosity (achieved through shallow beds)
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high mineral content
Media Growing Requirements
SESL worked on the growing media specifications for the plant walls. In Australia, the highly variable temperatures and rainfall require growing media to have:
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Decent rooting volume
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High moisture reserve
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High nutrient reserve
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Good continuity of maintenance
Mineral Ingredient Requirements
To meet the media requirements needed, more costly premium mineral ingredients were needed - Perlite, Vermiculite, Diatomite, Pumice, Horticultural ashes & <20% organic material. The organic material requirements were particularly fundamental as miscalculations would lead to the structural collapse of the green walls.
SESL also gave advice on the suggested fertilisers and application rates for the growing mix. The list is as follows:
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Gypsum at 500 g/m3
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Urea at 500 g/m3
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Iron Sulphate at 1.5kg/m3
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Magnesium Sulphate at 400 g/m3
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Lime or Dolomite at 600 g/m3
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Potassium Nitrate at 500 g/m3
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Superphosphate at 500 g/m3
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Trace Element Mix at 300 g/m3
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8/9 month Controlled Release at 5kg/m3
