Comparisons of extensive green roof media in Southern Ontario

Hill, Jenny C.; Drake, Jennifer; Sleep, Brent E.

doi:10.1016/j.ecoleng.2016.05.045

Cited by 34 publications

(21 citation statements)

References 28 publications

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“…In general, grasses performed better than forbs or sedum. In Hill et al [49], soil from 33 green roofs in the Southern Ontario region were sampled and analysed in a lab. In De-Ville et al [50], the physical properties of 12 green roof substrate cores (some virgin, some 5 years old from green roof test beds) are evaluated using XMT imaging.…”

Section: Hydrologymentioning

confidence: 99%

Performance of Blue-Green Roofs in Cold Climates: A Scoping Review

et al. 2018

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Green and blue-green roofs are emerging as an increasingly popular feature of rooftops, particularly in urban areas. Particular problematic conditions render their usage complex in the Nordic countries. In order to ensure that green roofs are built durable and with the service life expected of them, it is important to know all the relevant factors surrounding their construction and operation. A scoping study was conducted in order to gain an overview on green roof research and available scientific literature. One hundred articles of particular interest for Nordic climates were retrieved and their findings summarized. It is found that the vast majority of green roof research has been conducted on a theoretical basis, or with practical measurements on green roof test beds or isolated components. There is scarcely any literature on the operation of full-scale, building-implemented green roofs, and no articles were found on the building technical performance of aged green roofs. These knowledge gaps indicate a major risk factor in green roof operation, as their performance and integrity over time has not been documented. This despite the fact that green roofs have been implemented and in operation worldwide for decades.

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Section: Hydrologymentioning

confidence: 99%

Performance of Blue-Green Roofs in Cold Climates: A Scoping Review

et al. 2018

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“…These materials came from a dry alluvial quarry located in the Paleodelta of the Durance River, in the plain of La Crau (Bouches-du-Rhône, France) 60 km south of the experimental site. Because using inorganic substrate alone may limit plant growth, organic matter was added [28,42,43]. This organic amendment (NF U 44-051) was in the form of green compost with 52% dry matter, 22% organic matter, 0.75% total nitrogen and potassium oxide for up to 0.5% of the mass of the crude product.…”

Section: Experimental Protocolmentioning

confidence: 99%

“…European and international recommendations for green roof supports involve substrates based on granular mineral materials or lightweight aggregates, such as volcanic pumice (pozzolana), expanded slate, sand, crushed brick or concrete [26,27]. In other cases, composted materials are commonly used as substrate [28,29]. The ideal substrate results in a freely draining combination of coarse aggregates, with more or less organic content [30].…”

Section: Introductionmentioning

confidence: 99%

Substrate Composition and Depth Affect Soil Moisture Behavior and Plant-Soil Relationship on Mediterranean Extensive Green Roofs

Chenot

Gaget

Moinardeau

et al. 2017

Water

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Abstract:The Mediterranean basin is extremely vulnerable to climate change, and one of the areas most impacted by human water demand. Yet the green roofs increasingly created both for aesthetic reasons and to limit pollution and urban runoff are themselves very water-demanding. Successful green roof installation depends on the establishment of the vegetation, and the substrate is the key element: it conserves water, and provides the nutrients and physical support indispensable for plant growth. Since typical Mediterranean plant communities require no maintenance, this study seeks to develop techniques for creating maintenance-and watering-free horizontal green roofs for public or private buildings in a Mediterranean context. The innovative aspect of this study lies in creating two soil mixes, fine elements (clay and silt) and coarse elements (pebbles of all sizes), in two different thicknesses, to assess vegetation development. Monitoring of substrate moisture was carried out and coupled with local rainfall measurements during summer and autumn. As expected, substrate moisture is mainly influenced by substrate depth (the deeper, the moister) and composition (the finer the particles (clays and silts), the higher the moisture content). Vegetation cover impacts moisture to a lesser extent but is itself affected by the composition and depth of the substrates. These results are subsequently discussed with relation to the issue of sustainable green roofs in Mediterranean climates. Considering applications of our results, for an optimal colonization of a Mediterranean vegetation, a substrate thickness of 15 cm composed mainly of fine elements (75% clay-silt and 25% pebble-sand) would be recommended in green roofs.

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“…Mineral-based examples include lightweight expanded shale or clay, crushed brick, and other recycled construction materials; biologically derived examples include chipped bark, wood mulch, and composted wood products. In the European market, mixtures usually contain a small fraction of biological material, in concordance with the guidelines of Forschungsgesellschaft Landschaftsentwicklung-Landschaftsbau (2008), whereas in some North American regions, soilless mixtures containing a much higher proportion of organic matter (OM) are being used (Hill et al, 2016). The organic content is frequently needed to provide nutrients to support plant growth, and the biological material is typically lighter weight (Sandoval et al, 2017).…”

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confidence: 99%

The Effect of Intraparticle Porosity and Interparticle Voids on the Hydraulic Properties of Soilless Media

Hill

Sleep

Drake

et al. 2019

Vadose Zone Journal

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Core Ideas Green roofs comprise a soilless medium over an atmospheric equilibrated space. Green roofs represent microcosms of capillary fringe and vadose zone hydraulics. Bulk properties come from the interparticle voids and the intraparticle pores. Capillary retention is fundamental for water storage in a green roof system. Design specifications for green roofs should focus on using a well‐graded medium. An essential component of a building‐integrated vegetation system, such as an extensive green roof, is the layer of lightweight planting medium that supports rooting and stores water. Predicting and describing the stormwater management performance of green roofs requires reliable data regarding the water retention properties of the planting medium. Ten materials proposed for use on green roofs, including four mineral components, three biological components, and three commercial blends, were characterized through measurement of their water release curves (WRCs). In combination with the particle size distributions, the resultant data demonstrate that some of the materials contain measurable intraparticle pore networks in addition to the interparticle void spaces described in classical soil hydrology. The WRCs were also used to model the maximum water storage under static equilibrium conditions throughout a 15‐cm profile of each material. In freely draining, unsaturated green roof systems, the role of the intraparticle pores may be limited to increasing microscale roughness of particle surfaces, thereby reducing film flow under drier conditions. The highly organic, biologically derived materials—screened compost, bark fines, and shredded wood—demonstrated hydrophobicity when air dried, but wetting occurred within <30 min on all occasions, which would be within the time frame of many rainstorms. As with natural soils, the saturated hydraulic conductivity was lower in materials with a higher proportion of fines (<106 μm).

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Comparisons of extensive green roof media in Southern Ontario

Cited by 34 publications

References 28 publications

Performance of Blue-Green Roofs in Cold Climates: A Scoping Review

Performance of Blue-Green Roofs in Cold Climates: A Scoping Review

Substrate Composition and Depth Affect Soil Moisture Behavior and Plant-Soil Relationship on Mediterranean Extensive Green Roofs

The Effect of Intraparticle Porosity and Interparticle Voids on the Hydraulic Properties of Soilless Media

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