Functional green roofs: Importance of plant choice in maximising summertime environmental cooling and substrate insulation potential

Monteiro, Madalena Vaz; Blanuša, Tijana; Verhoef, Anne; Richardson, Murray; Hadley, P.; Cameron, Ross

doi:10.1016/j.enbuild.2017.02.011

Cited by 73 publications

(35 citation statements)

References 44 publications

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“…the the one-sided leaf area per unit ground surface, however, this seems relatively complex and impractical. Nevertheless, spectral measurements can provide interesting information: for example, a significant spread of the reflectivity spectrum was found (Vaz Monteiro et al 2017) in the NIR wavelength range (0.7-2.5 mm), not visible to the human eye but comprising more than 50% of solar radiation, for leaves of several genotypes having similar spectrum in the visible range (0.4-0.7 mm) and, therefore, similar color tone. The importance of the albedo is underlined in the "cool-green roof " concept proposed in Pisello et al (2016), in which plants that have high albedo but a compact greenery layer are selected as covering vegetation for flat roofs in historical or other contexts where the use of white solar-reflective cool roof coatings is not acceptable.…”

Section: Progress On Greenery Selection Plant Configuration and Urbamentioning

confidence: 99%

Progress in Urban Greenery Mitigation Science – Assessment Methodologies Advanced Technologies and Impact on Cities

Santamouris

Ban-Weiss

Osmond

et al. 2018

Journal of Civil Engineering and Management

140

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Urban greenery is a natural solution to cool cities and provide comfort, clean air and significant social, health and economic benefits. This paper aims to present the latest progress on the field of greenery urban mitigation techniques including aspects related to the theoretical and experimental assessment of the greenery cooling potential, the impact on urban vegetation on energy, health and comfort and the acquired knowledge on the best integration of the various types of greenery in the urban frame. Also to present the recent knowledge on the impact of climate change on the cooling performance of urban vegetation and investigate and analyse possible technological solutions to face the impact of high ambient temperatures.

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Section: Progress On Greenery Selection Plant Configuration and Urbamentioning

confidence: 99%

Progress in Urban Greenery Mitigation Science – Assessment Methodologies Advanced Technologies and Impact on Cities

Santamouris

Ban-Weiss

Osmond

et al. 2018

Journal of Civil Engineering and Management

140

View full text Add to dashboard Cite

show abstract

“…It is likely that for Stachys and probably Sedum, ETp in the TW and GW treatments remained similar through the drying period (hence resulting in similar water uptake). This suggests that the cooling service provided by the plants would not have been compromised by GW irrigation, as transpiration has previously been identified as the primary mechanism for cooling provision with these genotypes (Blanusa et al, 2013;Vaz Monteiro et al, 2017). Conversely, water uptake from plants irrigated with GW compared to TW was significantly lower for almost the whole experiment for Heuchera and significantly lower towards the end of the week for Control and Salvia (Table 2).…”

Section: Impact Of Gw On Plant Water Use After 6 Weeks Of Gw Irrigationmentioning

confidence: 71%

“…This contrasts with the results of Sharvelle et al (2012), who reported significantly higher water uptake by plants irrigated with GW than by plants irrigated with TW, although this was partly attributed to greater growth of the GW irrigated plants, which was not the case in this study. Lower water uptake from Heuchera irrigated with GW compared to TW corresponds to the reduced gs for the GW irrigated plants measured in Week 6, indicating a likely reduction in the cooling potential of Heuchera at this time (Vaz Monteiro et al, 2017). Since water uptake was significantly lower from the GW irrigated control containers compared to the TW irrigated containers, evaporation from the substrate, as well as transpiration, appears to be reduced with GW irrigation.…”

Section: Impact Of Gw On Plant Water Use After 6 Weeks Of Gw Irrigationmentioning

confidence: 78%

“…Additionally, there were no differences in the canopy temperatures of TW and GW irrigated plants within all genotypes at any time throughout the study (data not shown). Since high gs has proven to be a key trait for providing cooling with these genotypes (Vaz Monteiro et al, 2017), results suggest that the extent of the cooling service provided would not be compromised by irrigation with GW.…”

Section: Stomatal Conductancementioning

confidence: 99%

“…The principal objectives of this study, therefore, were to investigate the tolerance of some potential GR genotypes to short-term irrigation with GW (in terms of effects on their health, growth and functioning). Extensive previous research within our group with these genotypes under similar conditions identified plant transpiration as the primary mechanism through which cooling is provided, with gs also closely linked to the plants' cooling potential (Blanusa et al, 2013;Vaz Monteiro et al, 2016;2017). The impact of GW on continued provision of ESs, particularly cooling, through modification of stomatal conductance and associated ETp was therefore also investigated in this study.…”

Section: Introductionmentioning

confidence: 96%

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Greywater impact on green roofs’ provision of ecosystem services

Kemp¹,

Blanuša²,

Hadley³

2017

Acta Hortic.

Self Cite

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Previous research showed that some herbaceous perennial species could offer summertime cooling better than succulent species on green roofs (GRs), if supplementary irrigation is available during times of drought. In light of increasing water shortages, use of greywater (GW) instead of mains tap water (TW) for this purpose comes into focus. A glasshouse experiment was conducted in summer 2015 at the University of Reading (UK) to assess the impact of GW irrigation on the health, growth and functioning (in terms of leaf stomatal conductance (gs) and associated water uptake) of four plant genotypes (Salvia, Stachys, Heuchera and Sedum), and their ability to deliver ecosystem services, particularly cooling. Twenty-two replicates of each genotype, plus controls of bare, unvegetated substrate, were irrigated with fixed volumes of TW or synthetic GW for 6 weeks. Plant growth and visual quality, and gs were measured. In Week 7, daily water loss from each container following saturation was determined. For the first 6 weeks, plant growth, visual quality and gs were similar for both TW and GW treatments for all genotypes, indicating no negative impact of short-term GW irrigation and no apparent impact on cooling when plants were well-watered. However, in Week 7 water uptake (and thus presumably gs) was significantly lower for plants irrigated with GW compared to TW for some genotypes (Salvia and Heuchera), especially as substrate became drier, suggesting a reduction in evapotranspiration and potentially reduced cooling service when the soil is dry.

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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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Functional green roofs: Importance of plant choice in maximising summertime environmental cooling and substrate insulation potential

Cited by 73 publications

References 44 publications

Progress in Urban Greenery Mitigation Science – Assessment Methodologies Advanced Technologies and Impact on Cities

Progress in Urban Greenery Mitigation Science – Assessment Methodologies Advanced Technologies and Impact on Cities

Greywater impact on green roofs’ provision of ecosystem services

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

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