Evaluation of the cooling effect provided by a green façade as nature-based system for buildings

Convertino, Fabiana; Vox, Giuliano; Schettini, Evelia

doi:10.1016/j.buildenv.2021.108099

Cited by 49 publications

(22 citation statements)

References 42 publications

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“…Being a GF, LAI was considered as normal to the vertical surface. This was directly evaluated, according to Convertino et al [34], when the plant was fully grown and resulted equal to 4.11 (the facade on the right in Figure 1).…”

Section: Methodsmentioning

confidence: 99%

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Effect of Leaf Area Index on Green Facade Thermal Performance in Buildings

et al. 2022

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Green facades applied on a building’s envelope allow achieving the building’s passive thermal control and energy consumption reduction. These are complex systems and many site- and plant-specific parameters influence their energy behavior. The leaf area index (LAI) is a relevant plant characteristic to consider. Solar shading and latent heat loss of plant evapotranspiration are the two main cooling mechanisms. The aim of this study was to assess the cooling effect provided by an evergreen south oriented green facade in summer in a Mediterranean area and to investigate what happens when LAI changes. Experimental data were used to calculate the cooling effect provided by the facade. Simulations with different LAI values were performed to determine the related cooling effect. The canopy solar transmissivity decreased by 54% for every LAI unit increase. LAI significantly influenced the green facade cooling performance. As LAI increased, solar shading and latent heat increased; this was relevant until an upper limit value of 6. An exponential equation to calculate the mean extinction coefficient (km), and a polynomial relationship, with very good agreement, were proposed to calculate shading and latent heat as function of LAI. The findings of this research can effectively contribute to fill still existing gaps on green facades’ energy performance and to the energy simulation of buildings equipped with them.

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Section: Methodsmentioning

confidence: 99%

“…The latent heat of evapotranspiration (Φ, W m −2 ) was calculated from the canopy scale version of the Penman-Monteith [34,35] relationship:…”

Section: Methodsmentioning

confidence: 99%

Effect of Leaf Area Index on Green Facade Thermal Performance in Buildings

et al. 2022

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“…Studies on vertical greenery systems suggest that these interact with the building mainly by increasing the envelope thermal insulation, shading, mitigating the air velocity and providing cooling through evapotranspiration. The shading effect and the plant evapotranspiration, responsible for air and wall surface temperature reduction, are particularly effective in warm periods and contribute to reduce cooling demand (Bakhshoodeh et al, 2022;Blanco et al, 2021;Convertino et al, 2021;Lee and Jim, 2019;Zheng et al, 2020).…”

Section: Bwmentioning

confidence: 99%

A nature-based system for improving Mediterranean buildings’ performance: contribution to energy saving by heat transfer reduction and influence of climatic parameters

et al. 2023

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Urban environments can be turned greener and more sustainable by letting in vegetation. The application of green façades on buildings’ vertical surfaces is a viable option that brings various advantages. This study focuses on the energy benefit provided by an evergreen green façade in Mediterranean climate conditions. The results came from a long experimental campaign, heat fluxes evaluation and statistical analyses. The thermal behaviour of the experimental green façade was analysed all year round, highlighting differences between warm and cold periods and between time of the day. The main advantage was assessed in terms of energy saving, defined as heat flux reduction through the wall covered with vegetation in comparison with an unvegetated wall. The study pointed out that energy saving was achieved throughout the year, but in different time of the day based on the season. A daytime energy saving was obtained in warm periods due to the shading effect and the plants evapotranspiration. A night-time benefit was reached in cold periods mainly thanks to the thermal and wind barrier action of the green layer. The results showed daily mean values of energy saving equal to 11.47 W m-2 for a warm period and to 3.23 W m-2 for a cold period. The statistical analysis highlighted that the energy saving was positively influenced by external air temperature especially at daytime. Overall, higher energy saving was provided by the green façade when higher external air temperature values were recorded. This research contributes to fill existing literature gaps on the yearly behaviour of green façades and on the energy benefits these provide.

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“…In the case of GBSs and some GCSs, irrigation can be provided from the ground; however, green walls require irrigation of the entire vertical surface. Despite the potential drought tolerance of plants, in order to achieve the optimum cooling potential from GW systems, a sufficient to high level of irrigation is be required [32]. As plants become stressed from lack of water, their pores close and the rate of transpiration decreases.…”

Section: Gbs Gw Gcsmentioning

confidence: 99%

Nature-Based Solutions (NBSs) to Mitigate Urban Heat Island (UHI) Effects in Canadian Cities

et al. 2022

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Canada is warming at double the rate of the global average caused in part to a fast-growing population and large land transformations, where urban surfaces contribute significantly to the urban heat island (UHI) phenomenon. The federal government released the strengthened climate plan in 2020, which emphasizes using nature-based solutions (NBSs) to combat the effects of UHI phenomenon. Here, the effects of two NBSs techniques are reviewed and analysed: increasing surface greenery/vegetation (ISG) and increasing surface reflectivity (ISR). Policymakers have the challenge of selecting appropriate NBSs to meet a wide range of objectives within the urban environment and Canadian-specific knowledge of how NBSs can perform at various scales is lacking. As such, this state-of-the-art review intends to provide a snapshot of the current understanding of the benefits and risks associated with the implantation of NBSs in urban spaces as well as a review of the current techniques used to model, and evaluate the potential effectiveness of UHI under evolving climate conditions. Thus, if NBSs are to be adopted to mitigate UHI effects and extreme summertime temperatures in Canadian municipalities, an integrated, comprehensive analysis of their contributions is needed. As such, developing methods to quantify and evaluate NBSs’ performance and tools for the effective implementation of NBSs are required.

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Evaluation of the cooling effect provided by a green façade as nature-based system for buildings

Cited by 49 publications

References 42 publications

Effect of Leaf Area Index on Green Facade Thermal Performance in Buildings

Effect of Leaf Area Index on Green Facade Thermal Performance in Buildings

A nature-based system for improving Mediterranean buildings’ performance: contribution to energy saving by heat transfer reduction and influence of climatic parameters

Nature-Based Solutions (NBSs) to Mitigate Urban Heat Island (UHI) Effects in Canadian Cities

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