Green Roofs as Urban Ecosystems: Ecological Structures, Functions, and Services

Oberndorfer, Erica; Lundholm, Jeremy; Bass, Brad; Coffman, Reid R; Doshi, Hitesh; Dunnett, Nigel; Gaffin, Stuart R.; Köhler, Manfred; Liu, Karen KY; Rowe, Bradley

doi:10.32920/14668800

Cited by 18 publications

(24 citation statements)

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“…For instance, Oberndorfer et al (2007) expressed a general concern for Sedum (succulents such as Portulaca and Setcreasea) as they are low-growing small plants, can store water in their leaves, could survive prolonged periods of dry weather and do not require so much watering while offering a good coverage due to its fast growth rate.…”

Section: Survey Of Related Studiesmentioning

confidence: 99%

An explorative study on the potential of green roofs providing thermal comfort conditions for indoor spaces in Kumasi, Ghana

Koranteng

Nyame-Tawiah

Gyimah

et al. 2021

OHI

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PurposeAs the global population keeps increasing with its associated urbanisation and climate change issues being experienced in various degrees worldwide, there is the need to find mitigating measures to improve thermal conditions within spaces. The study aimed to evaluate green roofs to determine whether they could provide thermal comfort within residential buildings.Design/methodology/approachForty-two-year weather data were retrieved from the Kumasi weather station to establish the pattern of the climatic variables. Furthermore, an experiment was conducted by constructing test cells to determine the potential of vegetation/green roofs on temperature development within spaces. This approach led to a simulation-based exploration of the thermal performance of the test cells to probe variables that could lead to the reduction in temperature after the models in the software (design-builder) had been validated.FindingsThe results on the 42 years (1976–2018) weather data showed a significant (p = 0.05) mean temperature increment of 2.0 °C. The constructed test cell with Setcreasea purpurea (Purple Heart) vegetation showed an annual mean temperature reduction of 0.4 °C (p = 0.05). In addition, the exploration using the simulation application showed combinations of various soil depth (70–500 mm) and leaf area indices (leaf area index of 2–5) having a potential to lower indoor temperature by 1.5 °C and its associated reduction in energy use. The option of green roofs as a valuable alternative to conventional roofs, given their potential in mitigating climate change, must be encouraged. A survey of occupants in six selected neighbourhoods in Kumasi showed varying subjective perceptions of several green issues (24–98%) and increases in temperature values because of the loss of greenery in the city.Originality/valueEmpirical data that point to the significant reduction of indoor temperature values and a subsequent reduction in energy use have been unearthed. Therefore, built environment professionals together with city authorities could invest in these sustainable measures to help humanity.

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Section: Survey Of Related Studiesmentioning

confidence: 99%

An explorative study on the potential of green roofs providing thermal comfort conditions for indoor spaces in Kumasi, Ghana

Koranteng

Nyame-Tawiah

Gyimah

et al. 2021

OHI

View full text Add to dashboard Cite

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“…Green roofs decrease the substantial amount of heat transferred from the roofs to the inside of buildings by shading and evapotranspiration. The roofs' vegetation also extends the roofs' life span by protecting UV radiation, bad weather effects, and temperature fluctuations [122]. Quantitative thermal impacts of green roofs have been investigated through field experiments and mathematical approaches by some studies [123][124][125][126].…”

Section: Green Roofsmentioning

confidence: 99%

Causes, Modeling and Mitigation of Urban Heat Island: A Review

Imran¹,

Shammas²,

Rahman³

et al. 2021

EARTH

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Urbanization leads to loss of vegetation and converting pervious areas into built-up and impervious areas, and consequently, urban areas expose higher temperatures as compared to surrounding rural areas, which is called Urban Heat Island (UHI). The UHI affects the urban environment and causes heat-related diseases and mortality that have increased over the last centuries. Considering the severity of the UHI problem, enormous research has been conducted and an extensive range of literature is available on this topic. This paper reviews the causes, modelling and mitigation strategies of the UHI. The urban infrastructure and anthropogenic heat sources are the main driving factors in developing the UHI in cities. Many approaches including observation and modelling techniques are used to understand the formation, causes and mitigation of the UHI. The formation and causes of the UHI largely depend on the size, shape and urban infrastructure of the cities as well as climatic conditions. Although various modelling techniques are used to study UHI, there are still lacks in all models to precisely represent the physical phenomena and complex urban infrastructure. Many UHI mitigation strategies are examined by numerous studies, while the increased urban vegetation is a more environmentally friendly solution. The study summarizes the important features and limitations of different modelling techniques and mitigation measures of the UHI. This study also identifies research gaps and proposes areas for further research.

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“…Extensive green roofs (EGRs) are characterized by substrate depth of <15–20 cm, where only small‐sized vegetation such as herbs and small shrubs can thrive (Oberndorfer et al, 2007). EGRs are more affordable than intensive green roofs (characterized by deeper substrates) in terms of construction and maintenance costs and are thus suitable for retrofitting of many buildings.…”

Section: Introductionmentioning

confidence: 99%

Green roof irrigation management based on substrate water potential assures water saving without affecting plant physiological performance

et al. 2022

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Irrigation management in extensive green roofs (EGRs) is crucial in Mediterranean and semi‐arid climates, as it should guarantee efficient water use while ensuring plant survival and vegetation cover. However, benefits of maintaining moderately low substrate water potential (Ψs) have not been adequately investigated to date. An irrigation control unit based on Ψs thresholds for irrigation (MediWater Safe [MWS]) was compared to a common irrigation timer maintaining Ψs ⁓ 0 MPa (CTR) in shrub‐vegetated Mediterranean EGR modules. The effect of the different irrigation regimes on substrate temperature, plant water relations (leaf conductance to water vapour, midday water potential and turgor loss point) and root vulnerability to heat stress via electrolyte leakage was tested in four shrub species. Decreasing Ψs thresholds to −0.4 MPa reduced irrigation volumes by 68% in 3 summer months. However, the MWS unit neither influenced plant water status and vegetation cover nor induced physiological acclimation responses. Brief irrigation cycles imposed by MWS in the warmest hours reduced substrate surface temperature by 3°C compared to CTR. Plant water status dynamics and root vulnerability to heat were species specific. Progressive stomatal closure and plant decline occurred only in Ceanothus thyrsiflorus and were associated to high root vulnerability to heat. Mortality occurred only in some Ceanothus plants in the CTR module, where higher Ψs favoured the expansion of Hyperucum x moserianum. The results suggest that selecting proper Ψs thresholds for irrigation could optimize EGR benefits, guaranteeing substantial water savings and proper plant establishment. Moreover, we claim root resistance to heat as a key parameter for plant selection in Mediterranean EGRs.

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Green Roofs as Urban Ecosystems: Ecological Structures, Functions, and Services

Abstract: Green Roofs as Urban Ecosystems: Ecological Structures, Functions, and Services

Cited by 18 publications

References 0 publications

An explorative study on the potential of green roofs providing thermal comfort conditions for indoor spaces in Kumasi, Ghana

An explorative study on the potential of green roofs providing thermal comfort conditions for indoor spaces in Kumasi, Ghana

Causes, Modeling and Mitigation of Urban Heat Island: A Review

Green roof irrigation management based on substrate water potential assures water saving without affecting plant physiological performance

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