Porous Media Characterization to Simulate Water and Heat Transport through Green Roof Substrates

Sandoval, Victoria; Bonilla, Carlos A.; Gironás, Jorge; Vera, Sergio; Victorero, Felipe; Bustamante, Waldo; Rojas, Victoria; Leiva, Eduardo; Pastén, Pablo; Suárez, Francisco

doi:10.2136/vzj2016.10.0101

Cited by 28 publications

(35 citation statements)

References 56 publications

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“…Green roofs have been extensively adopted over the last few decades as a technological solution for sustainable development [1][2][3], as they integrate vegetation into buildings to minimize some negative impacts of urbanization [2][3][4][5]. A properly designed green roof can reduce pollution, noise levels, building energy consumption, and stormwater runoff [2,6,7]. At the same time, green roofs increase biodiversity and provide ecological services in urban environments [8,9].…”

Section: Introductionmentioning

confidence: 99%

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A New Method to Determine How Compaction Affects Water and Heat Transport in Green Roof Substrates

Sandoval

Suárez

2019

Applied Sciences

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Although compaction affects water and heat transport processes in porous media, few studies have dealt with this problem. This is particularly true for substrates, which are artificial porous media used for engineering and technological solutions, such as in vegetated or green roofs. We propose a methodology to study the effect of substrate compaction on the characterization of physical, hydrodynamic and thermal properties of five green roof substrates. The methodology consists in a parametric analysis that uses the properties of a substrate with known bulk density, and then modifies the substrate properties to consider how compaction affects water and heat fluxes. Coupled heat and water transport numerical simulations were performed to assess the impact of the changes in the previous properties on the hydraulic and thermal performance of a hypothetical roof system. Our results showed that compaction reduced the amplitude of the fluctuations in the volumetric water content daily cycles, increasing the average water content and reducing the breakthrough time of the green roof substrates. Compaction changes the thermal behavior of the green roof substrates in different ways for each substrate due to the dependence of the air, water and soil fraction of each substrate.

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Section: Introductionmentioning

confidence: 99%

“…Green roof overall performance strongly relies on the interaction between environmental conditions and the green roof's biophysical components [2,5]. A systematic comprehension of the processes occurring in every component of a green roof, under site-specific conditions, is required to understand the benefits described above.…”

Section: Introductionmentioning

confidence: 99%

A New Method to Determine How Compaction Affects Water and Heat Transport in Green Roof Substrates

Sandoval

Suárez

2019

Applied Sciences

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“…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). However, the use of large quantities of biological material in green roof media has been associated with the leaching of excess nutrients in runoff water (Czemiel Berndtsson, 2010; Van Seters et al, 2009), and these media have been observed to shrink (Schindler et al, 2016) and become hydrophobic (Raviv et al, 2008b) when dried.…”

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confidence: 99%

“…There have been many laboratory studies describing the hydraulics of planting media for green roof applications (Babilis and Londra, 2011; Dal Ferro et al, 2014; Poë et al, 2015; Sandoval et al, 2017). Although these studies have focused on particle size and interparticle pore spaces, there remains a paucity of data regarding the hydraulic functions of coarse aggregates with intraparticle porous networks (Raviv et al, 2008b; Stovin et al, 2015), although data are emerging from a few nursery horticulture (Schindler et al, 2016) and green roof (Dal Ferro et al, 2014; Graceson et al, 2013a; Latshaw et al, 2009) research communities.…”

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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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“…Thus, they were maintained at optimum conditions from January through May 2017. The substrate used was composed of humus, vegetal soil and perlite [16,35]. Due to the requirement of Photosynthetically Active Radiation by the vegetation, 2.5 kWh•m −2 •day −1 of radiation was generated inside the test room.…”

Section: Experimental Site and Setupmentioning

confidence: 99%

Potential of Particle Matter Dry Deposition on Green Roofs and Living Walls Vegetation for Mitigating Urban Atmospheric Pollution in Semiarid Climates

et al. 2018

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Abstract:In the last two decades, the incorporation of green roofs and living walls in buildings has increased significantly worldwide because of their benefits such as building energy savings, promoting biodiversity, controlling water run-off, mitigating urban heat island effect, improving indoor and urban air quality, and connecting people with nature. However, few studies have quantified the impact of green roofs (GRs) and living walls (LWs) on mitigating air pollution, especially in semiarid climates where airborne particle matter (PM) levels are high. Therefore, the aim of this paper is quantifying the dry deposition of PM 10 and PM 2.5 by several vegetation species commonly used in GRs and LWs in semiarid climates. Five species (Pitosporum tobira, Lavandula angustifolia, Lampranthus spectabillis, Sedum album, and Sedum reflexum) for GRs and four species (Aptenia cordiflora, Erigeron karvinskianus, Sedum palmeri, and Sedum spurium p.) for LWs were tested in an experimental facility-through washing, filtering, and weighing-to quantify the dry deposition of PM 2.5 and PM 10 on vegetation leaves as well as PM captured by the leaf wax. The main result is that a significant amount of PM is deposited on the typical vegetation used in GRs and LWs in semiarid climates. However, large differences in PM dry deposition were found among species, ranging from 0.09 µg/cm 2 ·h −1 to 1.32 µg/cm 2 ·h −1 for PM 2.5 , 0.48 µg/cm 2 ·h −1 to 4.7 µg/cm 2 ·h −1 for PM 10 and 0.41 µg/cm 2 ·h −1 to 25.6 µg/cm 2 ·h −1 for leaf wax. The species that showed the highest potential to capture PM were S. album, S. reflexum, S. palmeri, and L. spectabillis. This study shows this green infrastructures can contribute to mitigate air pollution, thus GRs and LWs have the potential for being included in decontamination plans.

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Porous Media Characterization to Simulate Water and Heat Transport through Green Roof Substrates

Cited by 28 publications

References 56 publications

A New Method to Determine How Compaction Affects Water and Heat Transport in Green Roof Substrates

A New Method to Determine How Compaction Affects Water and Heat Transport in Green Roof Substrates

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

Potential of Particle Matter Dry Deposition on Green Roofs and Living Walls Vegetation for Mitigating Urban Atmospheric Pollution in Semiarid Climates

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