Study on heat fluxes of green roofs based on an improved heat and mass transfer model

Tian, Yudi; Bai, Xian–Xu; Qi, Ben; Sun, Lexiang

doi:10.1016/j.enbuild.2017.07.021

Cited by 29 publications

(13 citation statements)

References 20 publications

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“…Green roofs are divided into extensive with thin substrates (2–20 cm) and their limited range of plants, and intensive, with a thicker layer of soil [ 192 ]. Roofs are considered to be one of the hottest surfaces in the city [ 193 ]. Many studies have proven green roofs reduce the temperature in their immediate surroundings by up to 10–15 °C [ 191 ] and increase the thermal insulation of buildings, thus reducing energy transfer to buildings and the need for cooling [ 22 , 92 , 191 , 192 ].…”

Section: Resultsmentioning

confidence: 99%

Statistical Review of Quality Parameters of Blue-Green Infrastructure Elements Important in Mitigating the Effect of the Urban Heat Island in the Temperate Climate (C) Zone

Antoszewski

Świerk

Krzyżaniak

2020

IJERPH

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Urban Heat Island (UHI) effect relates to the occurrence of a positive heat balance, compared to suburban and extra-urban areas in a high degree of urbanized cities. It is necessary to develop effective UHI prevention and mitigation strategies, one of which is blue-green infrastructure (BGI). Most research work comparing impact of BGI parameters on UHI mitigation is based on data measured in different climate zones. This makes the implication of nature-based solutions difficult in cities with different climate zones due to the differences in the vegetation time of plants. The aim of our research was to select the most statistically significant quality parameters of BGI elements in terms of preventing UHI. The normative four-step data delimitation procedure in systematic reviews related to UHI literature was used, and temperate climate (C) zone was determined as the UHI crisis area. As a result of delimitation, 173 publications qualified for literature review were obtained (488 rejected). We prepared a detailed literature data analysis and the CVA model—a canonical variation of Fisher’s linear discriminant analysis (LDA). Our research has indicated that the BGI object parameters are essential for UHI mitigation, which are the following: area of water objects and green areas, street greenery leaf size (LAI), green roofs hydration degree, and green walls location. Data obtained from the statistical analysis will be used to create the dynamic BGI modeling algorithm, which is the main goal of the series of articles in the future.

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Section: Resultsmentioning

confidence: 99%

Statistical Review of Quality Parameters of Blue-Green Infrastructure Elements Important in Mitigating the Effect of the Urban Heat Island in the Temperate Climate (C) Zone

Antoszewski

Świerk

Krzyżaniak

2020

IJERPH

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“…Evapotranspiration and net long wave radiation dominate the energy balance of the green roof. In particular, (2017) [59] found that most of the absorbed radiation (about 40%) is dissipated as latent heat on the canopy.…”

Section: Latent Heat Flux Resultsmentioning

confidence: 99%

“…Some studies, around 35% of the literature reviewed, adopted simplified energy balance models because of the complex structures of green roofs that include canopy and soil. In particular, Tian et al (2017) [59] analysed the loss of water in the soil through evapotranspiration considering that it occurred only on the surface of soil while He et al (2016) [53] assumed that the change of soil water content is equal to water loss through evapotranspiration. All heat transfer models of green roofs take into account the latent heat flux due to evaporation of water from the substrate and transpiration of plants.…”

Section: Heat and Mass Transfer Models For Et In Green Roofsmentioning

confidence: 99%

The evapotranspiration process in green roofs: A review

Cascone

Coma

Gagliano

et al. 2019

Building and Environment

154

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Previous research has shown that most of the green roof benefits are related to the cooling effect. In the literature available, however, it is still not clear how and how much the evapotranspiration affects the performance of a green roof. In order to fill the gap in this research topic, this study carries out a review on the cooling effect due to the evapotranspiration process of green roofs. First of all, an overview of the evapotranspiration phenomenon in green roofs, as well as the equipment and methods used for its measurement are presented. Then, the main experimental results available in literature, the physicalmathematical models and the dynamic simulation software used for the evaluation of the latent heat flux are also analysed and discussed among the available literature. Moreover, this review proposes a classification of the results carried out by previous studies as function of the main parameters affecting the evapotranspiration process (e.g. volumetric water content, stomatal resistance, Leaf Area Index, solar radiation, wind velocity, relative humidity, soil thickness, and substrate composition). Additionally, a sensitivity analysis of the results obtained from the literature allowed underlining the correlation among the main factors affecting the evapotranspiration. Finally, a vision of the world area where green roof studies were performed is provided. From the results, it is possible to emphasize that most of the studies that evaluated the evapotranspiration used high precision load cells. Furthermore, all the heat transfer models of green roofs considered in this review took into account the latent heat flux due to evaporation of water from the substrate and plants transpiration, however, only few of them were experimentally validated.

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“…However, the quantification of ET from green roofs is limited, and green roof ET has not been well quantified or thoroughly modelled (Voyde, Fassman, Simcock, & Wells, ). Most studies used the estimates of ET to determine substrate moisture deficit to simulate the hydrological performance of green roofs (Harper, Limmer, Showalter, & Burken, ; Li & Babcock, ; Sherrard & Jacobs, ; Tian, Bai, Qi, & Sun, ). Marasco, Hunter, Culligan, Gaffin, and McGillis () found that the predictive model overestimated ET values in winter and underestimated ET in summer.…”

Section: Discussionmentioning

confidence: 99%

Green roofs: Effects of plant species used on runoff

Cao

et al. 2018

Land Degrad Dev

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Green roofs are becoming a major nature‐based solution worldwide to reduce urban stormwater runoff. Runoff reduction and retention mainly depend on the hydrological characteristics of substrates and the water use strategies of plants. However, little is known about how plant species affect the hydrological performance of green roofs. Two commonly used succulent plants and four turfgrass species were investigated for their impacts on the hydrological performance and runoff reduction of green roof lysimeters under controlled conditions using a rainfall simulator. The results showed that two succulent plants (Sedum lineare and Callisia repens) did not make significant contributions to canopy interception in any of the four seasons and made only minor contributions to evapotranspiration (ET) water loss in autumn and winter, resulting in minor effects on runoff reduction by the green roofs. Festuca arundinacea contributed 47.4–116.7% of water loss via transpiration and 36.5% of runoff reduction under a 25 mm day−1 rainfall intensity in spring and 48.0% of runoff reduction under a 10 mm day−1 rainfall intensity in winter. Poa pratensis, Lolium perenne, and Agrostis stolonifera also significantly reduced runoff. Runoff reductions by extensive green roofs were mainly caused by ET rather than by their canopy interceptions. Plant shoot biomass and ET were the primary factors controlling the runoff reduction by extensive green roofs. Our results strongly suggest that the runoff reduction capacity of extensive green roofs can be greatly improved by selecting plant species with a higher shoot biomass and ET rate.

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Study on heat fluxes of green roofs based on an improved heat and mass transfer model

Cited by 29 publications

References 20 publications

Statistical Review of Quality Parameters of Blue-Green Infrastructure Elements Important in Mitigating the Effect of the Urban Heat Island in the Temperate Climate (C) Zone

Statistical Review of Quality Parameters of Blue-Green Infrastructure Elements Important in Mitigating the Effect of the Urban Heat Island in the Temperate Climate (C) Zone

The evapotranspiration process in green roofs: A review

Green roofs: Effects of plant species used on runoff

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