Vertical greening systems can be used as a mean to improve the environmental conditions of dense urban areas. Several researches have proved the environmental benefits of green envelopes. It is still ...not clear if vertical greening systems are economically sustainable, differently several Life Cycle Cost Analysis and Cost–Benefit Analysis determined economic costs and benefits of green roofs. This paper presents a Cost–Benefit Analysis of different vertical greening systems – green façades and living wall systems – considering personal and social benefits and costs over their life cycle. Installation, maintenance, and disposal costs of each analysed system are compared with the related private and social benefits (increase of real estate value, savings for heating and air conditioning, cladding longevity, air quality improvement, etc.), determining three indicators: the Net Present Value (NPV), the Internal Rate of Return (IRR) and the Pay Back Period (PBP). The CBA demonstrated that some of the vertical greening systems analysed are economically sustainable. Economic incentives (tax reduction) could reduce personal initial cost allowing a wider diffusion of greening systems to reduce environmental issues in dense urban areas, such as urban heat island phenomenon and air pollution.
•This paper analyses the personal and social benefits of vertical greening systems.•A private and social cost–benefit analysis of vertical greening systems was conducted.•Some of the vertical greening systems analysed are economically sustainable.•Economic incentives could reduce personal initial costs allowing a wider diffusion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
► The LWS has a notable cooling effect on the wall. ► The exterior wall surface losses heat to the microclimate. ► The LWS is the cooling instrument and the air layer is the heat source of the ...microclimate. ► The LWS does not increase the humidity of the air layer nor bring more humidity to the indoor space. ► The LWS with a sealed air layer or a smaller w-v-d performs better in its cooling ability, but is more humid in the air layer.
This research aims to identify the microclimate of the living wall system (LWS) in a hot and humid climate and to examine how ventilation and different wall-vegetation distances (w-v-d) affect the thermal performance of the LWS. Two identical thermal labs are constructed with adjustable LWS installed on their west-facing walls in Wuhan, China. Three series of experiments were carried out. Results show that the LWS has a notable cooling effect to the wall surface and the indoor space. The microclimate created by the LWS features in a cool layer of air with identical mean relative humidity as the ambient air. Instead of gaining heat, the exterior wall surface is losing heat to the microclimate all day, where the LWS is the cooling instrument that removes heat by radiative heat exchange. The LWS with a sealed air layer performs better in cooling the wall surface than the LWS with a naturally ventilated air layer. Lastly, three comparison experiments tested the LWS with different w-v-d: 30mm, 200mm, 400mm, and 600mm. Results show that the smaller distance has better cooling effect but higher relative humidity in the air layer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Vertical green-living walls (VGWs) are a promising solution for sustainable building design. However, their effectiveness in improving indoor air quality and reducing energy consumption in real-world ...settings still needs to be studied. Here we aim to contribute to this understanding by examining six indoor plant species (Peperomia obtusifolia, Tradescantia spathacea, Chlorophytum comosum, Spathiphyllum wallisii, Aeschynanthus radicans, and Philodendron hederaceum) in a 15 m2 Patrick Blanc's VGW system established in a shared office space (∼140 m3 volume). Carbon dioxide (CO2) assimilation, transpiration, and stomatal conductance were measured under varying light conditions and CO2 levels. In addition, numerous sensors were placed in the room to assess impacts on the indoor environment. Results indicate that all species but one (Philodendron) were equally effective in reducing CO2. Tradescantia had the highest cooling effect via transpiration. All species except Tradescantia had a very low light compensation point (<5 μmol m−2 s−1 PPFD), indicating their efficiency at reducing CO2 levels even under low light conditions. The net cooling effect of the VGW was 2.5°C–4.5 °C when the ventilation system was on and 1.2°C–3.6 °C when it was off. There was also a positive effect on indoor air quality, with an average CO2 reduction of 5% and sometimes up to 50%. By conducting controlled CO2 enrichment experiments, we estimated a 20% energy consumption savings from reduced air ventilation, equivalent to 1400 kWh/year. These results suggest that VGWs can improve indoor environments and thermal comfort in workplace settings and highlight the importance of choosing appropriate plant species.
•Vertical green-living walls (VGWs) can improve indoor air quality and reduce energy use.•We studied six plant species in a hydroponic VGW system in a shared office space.•Chlorophytum and Spathiphyllum were the most effective in cooling and reducing CO2.•The VGW had a net 3 ° C-5 ° C cooling effect and CO2 reduction of 5%–50% in the room.•The VGW was estimated to save 20% energy consumption, equivalent to 1400 kWh/year.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Vertical Greenery Systems (VGS) installed on building façades have recently gained significant attention for its urban cooling potentials. While current research primarily leans on the Leaf Area ...Index to estimate the VGS cooling potentials, the evaporative cooling effects of VGS growing media, has largely been overlooked. In particular, the effect of plant growth form on air movement within the VGS, which could notably augment the rate of evapotranspiration, has commonly been ignored. To address this gap, our study undertakes a comprehensive thermal analysis of two distinct plant growth forms (porous and dense), combining systematic Computational Fluid Dynamics simulations with field experiments over a six-month period. Our results, for the first time, demonstrate that the provision of a porous VGS significantly enhances its cooling effects, which could even lead to a negative façade heat flux. Our findings offer a novel perspective for plant and growing media selection in VGS design.
•Porous plant growth form in VGS amplifies cooling effect by up to 1 °C within 800 mm.•Negative VGS facade heat flux of −2.32 W/m2 achieved with porous plant growth form.•16 % higher rate of evaporative cooling from growing media found in porous VGS.•Fully formed VGS crucial for optimal cooling and heat gain reduction.•VGS cooling is driven by complex mechanisms, beyond the mere effects of shading.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Bibliometric analysis of vertical greenery systems (VGS)-related literature is conducted using CiteSpace.•Network maps have been developed to visualize the intellectual background, ...development trends and the current research status of VGS.•The major contributing bodies of VGS research at micro, meso and macro levels and the degree of collaboration among them are explored.•VGS literature is classified into state-of-the-art knowledge structure to achieve eight distinct sub-domains.•The most prominent sub-domain of VGS is thermal control and energy savings.
Due to the rapid research advancements in vertical greenery systems (VGS) recently, the findings of VGS research are prolific. This study intends to visualize the intellectual background, main research frontiers and state-of-the-art knowledge structure of entire VGS domain by conducting a scientometric analysis using CiteSpace. The original research articles published between Jan 2000 to Sep 2021 were extracted from the Web of Science core collection (WOSCC) database and visualization networks of co-authorship, co-citation, co-occurrence, and cluster analysis of VGS related knowledge were developed to categorize the major contributing bodies involved in the flourishment of VGS-related research, such as, most prolific publications, highly productive authors, top contributing institutions, active countries, highly influential journals, documents, and keywords. Furthermore, current research hotspots and recently emerging sub-fields were discovered by using citation burst analysis, whereas cluster analysis was performed to categorize the entire VGS literature into knowledge clusters to achieve state-of-the-art knowledge structure of VGS domain consisting of various research themes. This study can be significantly helpful for scientists and engineers to distinguish among the most critical sub-domains of VGS literature and to identify the new research frontiers for focusing on the most significant aspects for future studies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Green roofs and green walls have negligible effect on UHI mitigation in winter.•The application scale factor is crucial in mitigating UHI.•BIVT wide application can efficiently mitigate UHI up to ...1 °C.•Green façades on high-rise buildings mitigate UHI more than green roofs.•Wind parallel canyons are preferable to orthogonal ones for green wall installation.
The proposed study investigates the effect of urban heat island mitigation scenarios by applying extensive green roofs, green façades, and living walls to two built areas within Turin and Rome, Italy. Three mitigation scenarios and a baseline one have been developed in ENVI-met software for each built area and run for a typical winter day, summer day, and summer day with a heat wave.
The simulation results show that building integrated vegetation technology-application on a single building has an irrelevant effect on local temperatures; contrariwise, building integrated vegetation technology-wide application can effectively mitigate urban warming. Furthermore, the effect of green roofs and green walls on urban temperature is negligible in winter, likely because of the limited plant activity and the reduced amount of incoming solar radiation. Results also show that green façades are more effective than green roofs in mitigating pedestrian-level air temperature when installed on high-rise buildings, and green walls are more beneficial in mitigating summer urban heat island when installed in canyons parallel to wind direction than in perpendicular ones. Depending on the mitigation scenario, average decreases in urban temperatures up to 1 °C can be reached in the whole selected built area, alleviating urban warming.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper reviews the state of art of vegetation systems and their effect on the indoor environmental quality (IEQ), based on scientific studies from the past 30 years. Some studies have shown that ...biophilic workspaces and interaction with plants may change human attitudes, behaviours, improve productivity and the overall well-being. Evapotranspiration from plants helps lowering the temperature around the planting environment and this can be utilised for air cooling and humidity control. Also, indoor greenery can be used to reduce sound levels as a passive acoustic insulation system. Living wall systems in combination with biofiltration are emerging technologies to provide beneficial effects on improvement of indoor comfort. Several studies have indicated that green systems may improve indoor air quality and that they have different pathways for pollutant removal of volatile organic compounds. The plant root zone in potted plants may be an effective area for removing volatile organic compounds under controlled conditions. In conclusion, the full capacity of plants in real-life settings will need to be clarified to establish the true pollutant-removal mechanisms and the general effect on IEQ. The effects of green systems in combination with mechanical elements such as conventional heating, ventilation and air conditioning would need to be studied.
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NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
Building-related green infrastructures can help reduce several problems associated with urban life. However, while green roofs are reasonably well established and researched, questions remain about ...the environmental sustainability of vertical greening systems. This article reviews the use of life cycle assessment (LCA) to answer these questions. Methodological choices made in current LCA studies for modeling vertical greening systems are assessed. It is shown that a wide variety in boundary conditions used and assumptions made is prevalent. Based on the lessons learned a framework outline is proposed as a first step towards a more standardized assessment methodology. This outline is built around the life cycle phases and the boundary conditions of vertical greening systems, complemented by case specific data requirements and delivered benefits. The reviewed studies are compared with the framework to identify gaps and opportunities for improvement of current practices. It can be concluded that, to correctly represent the environmental impact of vertical greening systems, the associated benefits need to be better accounted for. For some benefits, i.e., energy savings due to reduced heating/cooling demand, CO2 sequestration, and air pollution reduction, it should be possible to implement them into LCA studies in the short to medium term because basic models and data are available for integration in the state-of-the-art. For other benefits, such as impacts on biodiversity, noise reduction, and psychological and health effects, quantitative data are still lacking, and additional research should be carried out to enable their integration.
•LCA methodologies used for modelling vertical greening systems are explored.•Better modelling of the benefits of vertical greening systems in LCA is needed.•Standardization is needed to ensure LCA results are comparable between studies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Removal of XOCs was higher using carbonaceous waste materials as compared to natural minerals.•Polar hydrophilic XOC showed highest removal using zeolite.•Low solubility and hydrophobic XOCs were ...best removed using coco coir.•Mixing zeolite with coco coir is recommended to remove wider range of XOCs.•Retention time of greywater in green wall should match the adsorption kinetics of XOCs.
Green walls can provide an aesthetic approach to treat domestic greywater in urban landscapes. However, the widespread adoption of green walls for greywater treatment depends on its performance to remove the emerging contaminants from greywater such as xenobiotic organic compounds (XOCs). In this study, the performance of five lightweight green wall media types (zeolite, perlite, date seeds, coffee grinds, and coco coir) was evaluated for the removal of six XOCs representing a range of hydrophilic to hydrophobic organic micropollutants in domestic greywater (acetaminophen, diethyltoluamide, bisphenol A, oxybenzone, triclosan, nonylphenol). The adsorption affinity of targeted XOCs on different green wall media types, the role of contact time on XOCs removal, and the impact of background pollutants in greywater matrix on the adsorption of XOCs were analysed. Results indicate that removal of XOCs was higher using carbonaceous waste materials (date seeds, coffee grinds, and coco coir) as compared to natural minerals (zeolite and perlite). Moreover, the adsorption of XOCs increased with the increase in pollutant hydrophobicity. All XOCs showed highest removal using coco coir with fast adsorption kinetics, achieving 90% of the removal in 30 min. The only exception was acetaminophen that showed best removal using zeolite but exhibited slow adsorption kinetics with 90% of the removal attained in 24 h. The initial adsorption kinetics (<30 min) of XOCs in greywater were adversely affected by the presence of background pollutants, indicating the need of higher residence time of greywater in green wall system for better removal of XOCs. Based on the findings of this batch study, it is recommended to design a green wall system with more than 30 min of greywater residence time using a mixture of coco coir and zeolite for effective removal of XOCs from domestic greywater.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The use of stormwater biofilters (also known as bioretention systems and raingardens), in tropical and semi-arid areas is hindered by seasonal rainfall patterns which cause extended dry periods. ...These periods can result in plant die-off, long-term damage to system health and leaching of pollutants when stormwater inflows resume. Using an additional polluted water source during dry periods could minimise system stress and eliminate the need to irrigate biofilters with potable water during dry spells. As such, the presented laboratory study tested the seasonal operation of biofilters, by switching from stormwater treatment in wet months to greywater treatment in dry months. Forty-five single planted biofilter columns, incorporating sedges, grasses, understory ornamentals and vines, were subjected to four months of stormwater inflows, followed by three months of greywater inflows. We also investigated the impact of including a carbon source in the saturated zone on treatment performance. The results showed plant species selection to be critical for nitrogen and phosphorus removal, with consistently effective species such as Carex appressa and Canna x generalis able to maintain low outflow concentrations (e.g. total nitrogen of 0.2–0.3 mg/L and 0.3–0.6 mg/L, respectively) across both water sources. Low outflow phosphorus concentrations were associated with plant species that had high filterable reactive phosphorus removal across both water sources. Similarly, higher removal of ammonia and oxidised nitrogen was associated with lower overall nitrogen concentrations. In contrast, high removal of total suspended sediment (>94%), biochemical oxygen demand (>98%) and some heavy metals (e.g. lead >98% and copper >93%) was reported across all designs. The results suggest that with the careful selection of plant species, biofilters can be operated seasonally as a feasible and practical solution to maintaining system health during extended dry periods.
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•Biofilter inflows can be switched from stormwater to greywater in dry months.•Effective plant species maintained low outflow concentrations across both sources.•Removal of filterable reactive phosphorus linked to larger phosphorus reductions.•Under stormwater inflows, less total nitrogen outflow linked to oxidised nitrogen.•Under greywater inflows, reduction in ammonia linked to smaller nitrogen outflows.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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